Sample records for chirality fermion masses

  1. A Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies

    NASA Astrophysics Data System (ADS)

    Lu, Wei

    2017-09-01

    We propose a Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies in the context of composite Higgs bosons. Standard model fermions are represented by algebraic spinors of six-dimensional binary Clifford algebra, while ternary Clifford algebra-related flavor projection operators control allowable flavor-mixing interactions. There are three composite electroweak Higgs bosons resulted from top quark, tau neutrino, and tau lepton condensations. Each of the three condensations gives rise to masses of four different fermions. The fermion mass hierarchies within these three groups are determined by four-fermion condensations, which break two global chiral symmetries. The four-fermion condensations induce axion-like pseudo-Nambu-Goldstone bosons and can be dark matter candidates. In addition to the 125 GeV Higgs boson observed at the Large Hadron Collider, we anticipate detection of tau neutrino composite Higgs boson via the charm quark decay channel.

  2. Chiral fermions in asymptotically safe quantum gravity

    NASA Astrophysics Data System (ADS)

    Meibohm, J.; Pawlowski, J. M.

    2016-05-01

    We study the consistency of dynamical fermionic matter with the asymptotic safety scenario of quantum gravity using the functional renormalisation group. Since this scenario suggests strongly coupled quantum gravity in the UV, one expects gravity-induced fermion self-interactions at energies of the Planck scale. These could lead to chiral symmetry breaking at very high energies and thus to large fermion masses in the IR. The present analysis which is based on the previous works (Christiansen et al., Phys Rev D 92:121501, 2015; Meibohm et al., Phys Rev D 93:084035, 2016), concludes that gravity-induced chiral symmetry breaking at the Planck scale is avoided for a general class of NJL-type models. We find strong evidence that this feature is independent of the number of fermion fields. This finding suggests that the phase diagram for these models is topologically stable under the influence of gravitational interactions.

  3. Chiral fermions in asymptotically safe quantum gravity.

    PubMed

    Meibohm, J; Pawlowski, J M

    2016-01-01

    We study the consistency of dynamical fermionic matter with the asymptotic safety scenario of quantum gravity using the functional renormalisation group. Since this scenario suggests strongly coupled quantum gravity in the UV, one expects gravity-induced fermion self-interactions at energies of the Planck scale. These could lead to chiral symmetry breaking at very high energies and thus to large fermion masses in the IR. The present analysis which is based on the previous works (Christiansen et al., Phys Rev D 92:121501, 2015; Meibohm et al., Phys Rev D 93:084035, 2016), concludes that gravity-induced chiral symmetry breaking at the Planck scale is avoided for a general class of NJL-type models. We find strong evidence that this feature is independent of the number of fermion fields. This finding suggests that the phase diagram for these models is topologically stable under the influence of gravitational interactions.

  4. Minimally doubled fermions and spontaneous chiral symmetry breaking

    NASA Astrophysics Data System (ADS)

    Osmanaj (Zeqirllari), Rudina; Hyka (Xhako), Dafina

    2018-03-01

    Chiral symmetry breaking in massless QCD is a very important feature in the current understanding of low energy physics. Low - lying Dirac modes are suitable to help us understand the spontaneous chiral symmetry breaking, since the formation of a non zero chiral condensate is an effect of their accumulation near zero. The Banks - Casher relation links the spectral density of the Dirac operator to the condensate with an identity that can be read in both directions. In this work we propose a spectral method to achieve a reliable determination of the density of eigenvalues of Dirac operator near zero using the Gauss - Lanczos quadrature. In order to understand better the dynamical chiral symmetry breaking and use the method we propose, we have chosen to work with minimally doubled fermions. These kind of fermions have been proposed as a strictly local discretization of the QCD fermions action, which preserves chiral symmetry at finite cut-off. Being chiral fermions, is easier to work with them and their low - lying Dirac modes and to understand the dynamical spontaneous chiral symmetry breaking.

  5. New chiral fermions, a new gauge interaction, Dirac neutrinos, and dark matter

    DOE PAGES

    de Gouvea, Andre; Hernandez, Daniel

    2015-10-07

    Here, we propose that all light fermionic degrees of freedom, including the Standard Model (SM) fermions and all possible light beyond-the-standard-model fields, are chiral with respect to some spontaneously broken abelian gauge symmetry. Hypercharge, for example, plays this role for the SM fermions. We introduce a new symmetry, U(1) ν , for all new light fermionic states. Anomaly cancellations mandate the existence of several new fermion fields with nontrivial U(1) ν charges. We develop a concrete model of this type, for which we show that (i) some fermions remain massless after U(1) ν breaking — similar to SM neutrinos —more » and (ii) accidental global symmetries translate into stable massive particles — similar to SM protons. These ingredients provide a solution to the dark matter and neutrino mass puzzles assuming one also postulates the existence of heavy degrees of freedom that act as “mediators” between the two sectors. The neutrino mass mechanism described here leads to parametrically small Dirac neutrino masses, and the model also requires the existence of at least four Dirac sterile neutrinos. Finally, we describe a general technique to write down chiral-fermions-only models that are at least anomaly-free under a U(1) gauge symmetry.« less

  6. New chiral fermions, a new gauge interaction, Dirac neutrinos, and dark matter

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    de Gouvea, Andre; Hernandez, Daniel

    Here, we propose that all light fermionic degrees of freedom, including the Standard Model (SM) fermions and all possible light beyond-the-standard-model fields, are chiral with respect to some spontaneously broken abelian gauge symmetry. Hypercharge, for example, plays this role for the SM fermions. We introduce a new symmetry, U(1) ν , for all new light fermionic states. Anomaly cancellations mandate the existence of several new fermion fields with nontrivial U(1) ν charges. We develop a concrete model of this type, for which we show that (i) some fermions remain massless after U(1) ν breaking — similar to SM neutrinos —more » and (ii) accidental global symmetries translate into stable massive particles — similar to SM protons. These ingredients provide a solution to the dark matter and neutrino mass puzzles assuming one also postulates the existence of heavy degrees of freedom that act as “mediators” between the two sectors. The neutrino mass mechanism described here leads to parametrically small Dirac neutrino masses, and the model also requires the existence of at least four Dirac sterile neutrinos. Finally, we describe a general technique to write down chiral-fermions-only models that are at least anomaly-free under a U(1) gauge symmetry.« less

  7. Heavy and Light Quarks with Lattice Chiral Fermions

    NASA Astrophysics Data System (ADS)

    Liu, K. F.; Dong, S. J.

    The feasibility of using lattice chiral fermions which are free of O(a) errors for both the heavy and light quarks is examined. The fact that the effective quark propagators in these fermions have the same form as that in the continuum with the quark mass being only an additive parameter to a chirally symmetric anti-Hermitian Dirac operator is highlighted. This implies that there is no distinction between the heavy and light quarks and no mass dependent tuning of the action or operators as long as the discretization error O(m2a2) is negligible. Using the overlap fermion, we find that the O(m2a2) (and O(ma2)) errors in the dispersion relations of the pseudoscalar and vector mesons and the renormalization of the axial-vector current and scalar density are small. This suggests that the applicable range of ma may be extended to ~0.56 with only 5% error, which is a factor of ~2.4 larger than the corresponding range of the improved Wilson action. We show that the generalized Gell-Mann-Oakes-Renner relation with unequal masses can be utilized to determine the finite ma corrections in the renormalization of the matrix elements for the heavy-light decay constants and semileptonic decay constants of the B/D meson.

  8. Three-dimensional Majorana fermions in chiral superconductors

    DOE PAGES

    Kozii, Vladyslav; Venderbos, Jorn W. F.; Fu, Liang

    2016-12-07

    Using a systematic symmetry and topology analysis, we establish that three-dimensional chiral superconductors with strong spin-orbit coupling and odd-parity pairing generically host low-energy nodal quasiparticles that are spin-nondegenerate and realize Majorana fermions in three dimensions. By examining all types of chiral Cooper pairs with total angular momentum J formed by Bloch electrons with angular momentum j in crystals, we obtain a comprehensive classification of gapless Majorana quasiparticles in terms of energy-momentum relation and location on the Fermi surface. We show that the existence of bulk Majorana fermions in the vicinity of spin-selective point nodes is rooted in the nonunitary naturemore » of chiral pairing in spin-orbit–coupled superconductors. We address experimental signatures of Majorana fermions and find that the nuclear magnetic resonance spin relaxation rate is significantly suppressed for nuclear spins polarized along the nodal direction as a consequence of the spin-selective Majorana nature of nodal quasiparticles. Furthermore, Majorana nodes in the bulk have nontrivial topology and imply the presence of Majorana bound states on the surface, which form arcs in momentum space. We conclude by proposing the heavy fermion superconductor PrOs 4Sb 12 and related materials as promising candidates for nonunitary chiral superconductors hosting three-dimensional Majorana fermions.« less

  9. Three-dimensional Majorana fermions in chiral superconductors.

    PubMed

    Kozii, Vladyslav; Venderbos, Jörn W F; Fu, Liang

    2016-12-01

    Using a systematic symmetry and topology analysis, we establish that three-dimensional chiral superconductors with strong spin-orbit coupling and odd-parity pairing generically host low-energy nodal quasiparticles that are spin-nondegenerate and realize Majorana fermions in three dimensions. By examining all types of chiral Cooper pairs with total angular momentum J formed by Bloch electrons with angular momentum j in crystals, we obtain a comprehensive classification of gapless Majorana quasiparticles in terms of energy-momentum relation and location on the Fermi surface. We show that the existence of bulk Majorana fermions in the vicinity of spin-selective point nodes is rooted in the nonunitary nature of chiral pairing in spin-orbit-coupled superconductors. We address experimental signatures of Majorana fermions and find that the nuclear magnetic resonance spin relaxation rate is significantly suppressed for nuclear spins polarized along the nodal direction as a consequence of the spin-selective Majorana nature of nodal quasiparticles. Furthermore, Majorana nodes in the bulk have nontrivial topology and imply the presence of Majorana bound states on the surface, which form arcs in momentum space. We conclude by proposing the heavy fermion superconductor PrOs 4 Sb 12 and related materials as promising candidates for nonunitary chiral superconductors hosting three-dimensional Majorana fermions.

  10. Three-dimensional Majorana fermions in chiral superconductors

    PubMed Central

    Kozii, Vladyslav; Venderbos, Jörn W. F.; Fu, Liang

    2016-01-01

    Using a systematic symmetry and topology analysis, we establish that three-dimensional chiral superconductors with strong spin-orbit coupling and odd-parity pairing generically host low-energy nodal quasiparticles that are spin-nondegenerate and realize Majorana fermions in three dimensions. By examining all types of chiral Cooper pairs with total angular momentum J formed by Bloch electrons with angular momentum j in crystals, we obtain a comprehensive classification of gapless Majorana quasiparticles in terms of energy-momentum relation and location on the Fermi surface. We show that the existence of bulk Majorana fermions in the vicinity of spin-selective point nodes is rooted in the nonunitary nature of chiral pairing in spin-orbit–coupled superconductors. We address experimental signatures of Majorana fermions and find that the nuclear magnetic resonance spin relaxation rate is significantly suppressed for nuclear spins polarized along the nodal direction as a consequence of the spin-selective Majorana nature of nodal quasiparticles. Furthermore, Majorana nodes in the bulk have nontrivial topology and imply the presence of Majorana bound states on the surface, which form arcs in momentum space. We conclude by proposing the heavy fermion superconductor PrOs4Sb12 and related materials as promising candidates for nonunitary chiral superconductors hosting three-dimensional Majorana fermions. PMID:27957543

  11. Direct optical detection of Weyl fermion chirality in a topological semimetal

    NASA Astrophysics Data System (ADS)

    Ma, Qiong; Xu, Su-Yang; Chan, Ching-Kit; Zhang, Cheng-Long; Chang, Guoqing; Lin, Yuxuan; Xie, Weiwei; Palacios, Tomás; Lin, Hsin; Jia, Shuang; Lee, Patrick A.; Jarillo-Herrero, Pablo; Gedik, Nuh

    2017-09-01

    A Weyl semimetal is a novel topological phase of matter, in which Weyl fermions arise as pseudo-magnetic monopoles in its momentum space. The chirality of the Weyl fermions, given by the sign of the monopole charge, is central to the Weyl physics, since it directly serves as the sign of the topological number and gives rise to exotic properties such as Fermi arcs and the chiral anomaly. Here, we directly detect the chirality of the Weyl fermions by measuring the photocurrent in response to circularly polarized mid-infrared light. The resulting photocurrent is determined by both the chirality of Weyl fermions and that of the photons. Our results pave the way for realizing a wide range of theoretical proposals for studying and controlling the Weyl fermions and their associated quantum anomalies by optical and electrical means. More broadly, the two chiralities, analogous to the two valleys in two-dimensional materials, lead to a new degree of freedom in a three-dimensional crystal with potential novel pathways to store and carry information.

  12. Optical Selection Rule of Excitons in Gapped Chiral Fermion Systems

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoou; Shan, Wen-Yu; Xiao, Di

    2018-02-01

    We show that the exciton optical selection rule in gapped chiral fermion systems is governed by their winding number w , a topological quantity of the Bloch bands. Specifically, in a CN-invariant chiral fermion system, the angular momentum of bright exciton states is given by w ±1 +n N with n being an integer. We demonstrate our theory by proposing two chiral fermion systems capable of hosting dark s -like excitons: gapped surface states of a topological crystalline insulator with C4 rotational symmetry and biased 3 R -stacked MoS2 bilayers. In the latter case, we show that gating can be used to tune the s -like excitons from bright to dark by changing the winding number. Our theory thus provides a pathway to electrical control of optical transitions in two-dimensional material.

  13. Three-Dimensional Majorana Fermions in Chiral Superconductors

    NASA Astrophysics Data System (ADS)

    Kozii, Vladyslav; Venderbos, Jorn; Fu, Liang

    Through a systematic symmetry and topology analysis we establish that three-dimensional chiral superconductors with strong spin-orbit coupling and odd-parity pairing generically host low-energy nodal quasiparticles that are spin-non-degenerate and realize Majorana fermions in three dimensions. By examining all types of chiral Cooper pairs with total angular momentum J formed by Bloch electrons with angular momentum j in crystals, we obtain a comprehensive classification of gapless Majorana quasiparticles in terms of energy-momentum relation and location on the Fermi surface. We show that the existence of bulk Majorana fermions in the vicinity of spin-selective point nodes is rooted in the non-unitary nature of chiral pairing in spin-orbit-coupled superconductors. We address experimental signatures of Majorana fermions, and find that the nuclear magnetic resonance spin relaxation rate is significantly suppressed for nuclear spins polarized along the nodal direction as a consequence of the spin-selective Majorana nature of nodal quasiparticles. Furthermore, Majorana nodes in the bulk have nontrivial topology and imply the presence of Majorana bound states on the surface that form arcs in momentum space. This work is supported by DOE Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award de-sc0010526 (LF and VK), and the Netherlands Organization for Scientific Research (NWO) through a Rubicon Grant (JV).

  14. Illuminating the chirality of Weyl fermions

    NASA Astrophysics Data System (ADS)

    Ma, Qiong; Xu, Su-Yang; Chan, Ching-Kit; Zhang, Cheng-Long; Chang, Guoqing; Lin, Hsin; Jia, Shuang; Lee, Patrick; Gedik, Nuh; Jarillo-Herrero, Pablo

    In particle physics, Weyl fermions (WF) are elementary particles that travel at the speed of light and have a definite chirality. In condensed matter, it has been recently realized that WFs can arise as magnetic monopoles in the momentum space of a novel topological metal, the Weyl semimetal (WSM). Their chirality, given by the sign of the monopole charge, is the defining property of a WSM, since it directly serves as the topological number and gives rise to exotic properties such as Fermi arcs and the chiral anomaly. Moreover, the two chiralities, analogous to the two valleys in 2D materials, lead to a new degree of freedom in a 3D crystal, suggesting novel pathways to store and carry information. By shining circularly polarized light on the WSM TaAs, we illuminate the chirality of the WFs and achieve an electrical current that is highly controllable based on the WFs' chirality. Our results open up a wide range of new possibilities for experimentally studying and controlling the WFs and their associated quantum anomalies by optical and electrical means, which suggest the exciting prospect of ``Weyltronics''.

  15. Fast algorithms for chiral fermions in 2 dimensions

    NASA Astrophysics Data System (ADS)

    Hyka (Xhako), Dafina; Osmanaj (Zeqirllari), Rudina

    2018-03-01

    In lattice QCD simulations the formulation of the theory in lattice should be chiral in order that symmetry breaking happens dynamically from interactions. In order to guarantee this symmetry on the lattice one uses overlap and domain wall fermions. On the other hand high computational cost of lattice QCD simulations with overlap or domain wall fermions remains a major obstacle of research in the field of elementary particles. We have developed the preconditioned GMRESR algorithm as fast inverting algorithm for chiral fermions in U(1) lattice gauge theory. In this algorithm we used the geometric multigrid idea along the extra dimension.The main result of this work is that the preconditioned GMRESR is capable to accelerate the convergence 2 to 12 times faster than the other optimal algorithms (SHUMR) for different coupling constant and lattice 32x32. Also, in this paper we tested it for larger lattice size 64x64. From the results of simulations we can see that our algorithm is faster than SHUMR. This is a very promising result that this algorithm can be adapted also in 4 dimension.

  16. Chiral phase transition of three flavor QCD with nonzero magnetic field using standard staggered fermions

    NASA Astrophysics Data System (ADS)

    Tomiya, Akio; Ding, Heng-Tong; Mukherjee, Swagato; Schmidt, Christian; Wang, Xiao-Dan

    2018-03-01

    Lattice simulations for (2+1)-flavor QCD with external magnetic field demon-strated that the quark mass is one of the important parameters responsible for the (inverse) magnetic catalysis. We discuss the dependences of chiral condensates and susceptibilities, the Polyakov loop on the magnetic field and quark mass in three degenerate flavor QCD. The lattice simulations are performed using standard staggered fermions and the plaquette action with spatial sizes Nσ = 16 and 24 and a fixed temporal size Nτ = 4. The value of the quark masses are chosen such that the system undergoes a first order chiral phase transition and crossover with zero magnetic field. We find that in light mass regime, the quark chiral condensate undergoes magnetic catalysis in the whole temperature region and the phase transition tend to become stronger as the magnetic field increases. In crossover regime, deconfinement transition temperature is shifted by the magnetic field when quark mass ma is less than 0:4. The lattice cutoff effects are also discussed.

  17. Fermion masses through four-fermion condensates

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ayyar, Venkitesh; Chandrasekharan, Shailesh

    Fermion masses can be generated through four-fermion condensates when symmetries prevent fermion bilinear condensates from forming. This less explored mechanism of fermion mass generation is responsible for making four reduced staggered lattice fermions massive at strong couplings in a lattice model with a local four-fermion coupling. The model has a massless fermion phase at weak couplings and a massive fermion phase at strong couplings. In particular there is no spontaneous symmetry breaking of any lattice symmetries in both these phases. Recently it was discovered that in three space-time dimensions there is a direct second order phase transition between the twomore » phases. Here we study the same model in four space-time dimensions and find results consistent with the existence of a narrow intermediate phase with fermion bilinear condensates, that separates the two asymptotic phases by continuous phase transitions.« less

  18. Lorentz symmetry violation in the fermion number anomaly with the chiral overlap operator

    NASA Astrophysics Data System (ADS)

    Makino, Hiroki; Morikawa, Okuto

    2016-12-01

    Recently, Grabowska and Kaplan proposed a four-dimensional lattice formulation of chiral gauge theories on the basis of a chiral overlap operator. We compute the classical continuum limit of the fermion number anomaly in this formulation. Unexpectedly, we find that the continuum limit contains a term which is not Lorentz invariant. The term is, however, proportional to the gauge anomaly coefficient, and thus the fermion number anomaly in this lattice formulation automatically restores the Lorentz-invariant form when and only when the anomaly cancellation condition is met.

  19. QCD phase transition with chiral quarks and physical quark masses.

    PubMed

    Bhattacharya, Tanmoy; Buchoff, Michael I; Christ, Norman H; Ding, H-T; Gupta, Rajan; Jung, Chulwoo; Karsch, F; Lin, Zhongjie; Mawhinney, R D; McGlynn, Greg; Mukherjee, Swagato; Murphy, David; Petreczky, P; Renfrew, Dwight; Schroeder, Chris; Soltz, R A; Vranas, P M; Yin, Hantao

    2014-08-22

    We report on the first lattice calculation of the QCD phase transition using chiral fermions with physical quark masses. This calculation uses 2+1 quark flavors, spatial volumes between (4 fm)(3) and (11 fm)(3) and temperatures between 139 and 196 MeV. Each temperature is calculated at a single lattice spacing corresponding to a temporal Euclidean extent of N(t) = 8. The disconnected chiral susceptibility, χ(disc) shows a pronounced peak whose position and height depend sensitively on the quark mass. We find no metastability near the peak and a peak height which does not change when a 5 fm spatial extent is increased to 10 fm. Each result is strong evidence that the QCD "phase transition" is not first order but a continuous crossover for m(π) = 135 MeV. The peak location determines a pseudocritical temperature T(c) = 155(1)(8) MeV, in agreement with earlier staggered fermion results. However, the peak height is 50% greater than that suggested by previous staggered results. Chiral SU(2)(L) × SU(2)(R) symmetry is fully restored above 164 MeV, but anomalous U(1)(A) symmetry breaking is nonzero above T(c) and vanishes as T is increased to 196 MeV.

  20. Fermion-number violation in regularizations that preserve fermion-number symmetry

    NASA Astrophysics Data System (ADS)

    Golterman, Maarten; Shamir, Yigal

    2003-01-01

    There exist both continuum and lattice regularizations of gauge theories with fermions which preserve chiral U(1) invariance (“fermion number”). Such regularizations necessarily break gauge invariance but, in a covariant gauge, one recovers gauge invariance to all orders in perturbation theory by including suitable counterterms. At the nonperturbative level, an apparent conflict then arises between the chiral U(1) symmetry of the regularized theory and the existence of ’t Hooft vertices in the renormalized theory. The only possible resolution of the paradox is that the chiral U(1) symmetry is broken spontaneously in the enlarged Hilbert space of the covariantly gauge-fixed theory. The corresponding Goldstone pole is unphysical. The theory must therefore be defined by introducing a small fermion-mass term that breaks explicitly the chiral U(1) invariance and is sent to zero after the infinite-volume limit has been taken. Using this careful definition (and a lattice regularization) for the calculation of correlation functions in the one-instanton sector, we show that the ’t Hooft vertices are recovered as expected.

  1. Topological susceptibility from twisted mass fermions using spectral projectors and the gradient flow

    NASA Astrophysics Data System (ADS)

    Alexandrou, Constantia; Athenodorou, Andreas; Cichy, Krzysztof; Constantinou, Martha; Horkel, Derek P.; Jansen, Karl; Koutsou, Giannis; Larkin, Conor

    2018-04-01

    We compare lattice QCD determinations of topological susceptibility using a gluonic definition from the gradient flow and a fermionic definition from the spectral-projector method. We use ensembles with dynamical light, strange and charm flavors of maximally twisted mass fermions. For both definitions of the susceptibility we employ ensembles at three values of the lattice spacing and several quark masses at each spacing. The data are fitted to chiral perturbation theory predictions with a discretization term to determine the continuum chiral condensate in the massless limit and estimate the overall discretization errors. We find that both approaches lead to compatible results in the continuum limit, but the gluonic ones are much more affected by cutoff effects. This finally yields a much smaller total error in the spectral-projector results. We show that there exists, in principle, a value of the spectral cutoff which would completely eliminate discretization effects in the topological susceptibility.

  2. Ward identities and chiral anomalies for coupled fermionic chains

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Costa, L. C.; Ferraz, A.; Mastropietro, Vieri

    2013-12-15

    Coupled fermionic chains are usually described by an effective model written in terms of bonding and anti-bonding fermionic fields with linear dispersion in the vicinities of the respective Fermi points. We derive for the first time exact Ward Identities (WI) for this model, proving the existence of chiral anomalies which verify the Adler-Bardeen non-renormalization property. Such WI are expected to play a crucial role in the understanding of the thermodynamic properties of the system. Our results are non-perturbative and are obtained analyzing Grassmann functional integrals by means of constructive quantum field theory methods.

  3. Baryon axial charges from chirally improved fermions - first results

    NASA Astrophysics Data System (ADS)

    Engel, G.; Gattringer, C.; Glozman, L. Y.; Lang, C. B.; Limmer, M.; Mohler, D.; Schäfer, A.

    We present first results from dynamical Chirally Improved (CI) fermion simulations for the axial charge $G_A$ of various hadrons. We work with 16^3x32 lattices of spatial extent 2.4 fm and use the variational method with a suitable basis of Jacobi-smeared interpolators to suppress contaminations from excited states.

  4. Chiral Majorana fermion modes in a quantum anomalous Hall insulator–superconductor structure

    DOE PAGES

    He, Qing Lin; Pan, Lei; Stern, Alexander L.; ...

    2017-07-21

    Majorana fermion is a hypothetical particle that is its own antiparticle. We report transport measurements that suggest the existence of one-dimensional chiral Majorana fermion modes in the hybrid system of a quantum anomalous Hall insulator thin film coupled with a superconductor. As the external magnetic field is swept, half-integer quantized conductance plateaus are observed at the locations of magnetization reversals, giving a distinct signature of the Majorana fermion modes. This transport signature is reproducible over many magnetic field sweeps and appears at different temperatures. This finding may open up an avenue to control Majorana fermions for implementing robust topological quantummore » computing.« less

  5. Fermion number anomaly with the fluffy mirror fermion

    NASA Astrophysics Data System (ADS)

    Okumura, Ken-ichi; Suzuki, Hiroshi

    2016-12-01

    Quite recently, Grabowska and Kaplan presented a 4-dimensional lattice formulation of chiral gauge theories based on the chiral overlap operator. We study this formulation from the perspective of the fermion number anomaly and possible associated phenomenology. A simple argument shows that the consistency of the formulation implies that the fermion with the opposite chirality to the physical one, the "fluffy mirror fermion" or "fluff", suffers from the fermion number anomaly in the same magnitude (with the opposite sign) as the physical fermion. This immediately shows that if at least one of the fluff quarks is massless, the formulation provides a simple viable solution to the strong CP problem. Also, if the fluff interacts with gravity essentially in the same way as the physical fermion, the formulation can realize the asymmetric dark matter scenario.

  6. Chiral Majorana fermion modes regulated by a scanning tunneling microscope tip

    NASA Astrophysics Data System (ADS)

    Zhou, Yan-Feng; Hou, Zhe; Zhang, Ying-Tao; Sun, Qing-Feng

    2018-03-01

    The Majorana fermion can be described by a real wave function with only two phases (zero and π ) which provide a controllable degree of freedom. We propose a strategy to regulate the phase of the chiral Majorana state by coupling with a scanning tunneling microscope tip in a system consisting of a quantum anomalous Hall insulator coupled with a superconductor. With the change in the chemical potential, the chiral Majorana state can be tuned alternately between zero and π , in which the perfect normal tunneling and perfect crossed Andreev reflection appear, respectively. The perfect crossed Andreev reflection, by which a Cooper pair can be split into two electrons going into different terminals completely, leads to a pumping current and distinct quantized resistances. These findings may provide a signature of Majorana fermions and pave a feasible avenue to regulate the phase of the Majorana state.

  7. Fermion localization and resonances on a de Sitter thick brane

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu Yuxiao; Yang Jie; Zhao Zhenhua

    2009-09-15

    In C. A. S. Almeida, R. Casana, M. M. Ferreira, Jr., and A. R. Gomes, Phys. Rev. D 79, 125022 (2009), the simplest Yukawa coupling {eta}{psi}{phi}{chi}{psi} was considered for a two-scalar-generated Bloch brane model. Fermionic resonances for both chiralities were obtained, and their appearance is related to branes with internal structure. Inspired on this result, we investigate the localization and resonance spectrum of fermions on a one-scalar-generated de Sitter thick brane with a class of scalar-fermion couplings {eta}{psi}{phi}{sup k}{psi} with positive odd integer k. A set of massive fermionic resonances for both chiralities is obtained when provided large coupling constantmore » {eta}. We find that the masses and lifetimes of left and right chiral resonances are almost the same, which demonstrates that it is possible to compose massive Dirac fermions from the left and right chiral resonances. The resonance with lower mass has longer lifetime. For a same set of parameters, the number of resonances increases with k and the lifetime of the lower level resonance for larger k is much longer than the one for smaller k.« less

  8. Signatures of the Adler–Bell–Jackiw chiral anomaly in a Weyl fermion semimetal

    DOE PAGES

    Zhang, Cheng-Long; Xu, Su-Yang; Belopolski, Ilya; ...

    2016-02-25

    Weyl semimetals provide the realization of Weyl fermions in solid-state physics. Among all the physical phenomena that are enabled by Weyl semimetals, the chiral anomaly is the most unusual one. Here, we report signatures of the chiral anomaly in the magneto-transport measurements on the first Weyl semimetal TaAs. We show negative magnetoresistance under parallel electric and magnetic fields, that is, unlike most metals whose resistivity increases under an external magnetic field, we observe that our high mobility TaAs samples become more conductive as a magnetic field is applied along the direction of the current for certain ranges of the fieldmore » strength. We present systematically detailed data and careful analyses, which allow us to exclude other possible origins of the observed negative magnetoresistance. Finally, our transport data, corroborated by photoemission measurements, first-principles calculations and theoretical analyses, collectively demonstrate signatures of the Weyl fermion chiral anomaly in the magneto-transport of TaAs.« less

  9. Adding gauge fields to Kaplan's fermions

    NASA Astrophysics Data System (ADS)

    Blum, T.; Kärkkäinen, Leo

    1994-04-01

    We experiment with adding dynamical gauge field to Kaplan (defect) fermions. In the case of U (1) gauge theory we use an inhomogenous Higgs mechanism to restrict the 3d gauge dynamics to a planar 2d defect. In our simulations the 3d theory produce the correct 2d gauge dynamics. We measure fermion propagators with dynamical gauge fields. They posses the correct chiral structure. The fermions at the boundary of the support of the gauge field (waveguide) are non-chiral, and have a mass two times heavier than the chiral modes. Moreover, these modes cannot be excited by a source at the defect; implying that they are dynamically decoupled. We have also checked that the anomaly relation is fullfilled for the case of a smooth external gauge field.

  10. Chiral Majorana fermion modes in a quantum anomalous Hall insulator-superconductor structure.

    PubMed

    He, Qing Lin; Pan, Lei; Stern, Alexander L; Burks, Edward C; Che, Xiaoyu; Yin, Gen; Wang, Jing; Lian, Biao; Zhou, Quan; Choi, Eun Sang; Murata, Koichi; Kou, Xufeng; Chen, Zhijie; Nie, Tianxiao; Shao, Qiming; Fan, Yabin; Zhang, Shou-Cheng; Liu, Kai; Xia, Jing; Wang, Kang L

    2017-07-21

    Majorana fermion is a hypothetical particle that is its own antiparticle. We report transport measurements that suggest the existence of one-dimensional chiral Majorana fermion modes in the hybrid system of a quantum anomalous Hall insulator thin film coupled with a superconductor. As the external magnetic field is swept, half-integer quantized conductance plateaus are observed at the locations of magnetization reversals, giving a distinct signature of the Majorana fermion modes. This transport signature is reproducible over many magnetic field sweeps and appears at different temperatures. This finding may open up an avenue to control Majorana fermions for implementing robust topological quantum computing. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  11. Entanglement Hamiltonians for Chiral Fermions with Zero Modes.

    PubMed

    Klich, Israel; Vaman, Diana; Wong, Gabriel

    2017-09-22

    In this Letter, we study the effect of topological zero modes on entanglement Hamiltonians and the entropy of free chiral fermions in (1+1)D. We show how Riemann-Hilbert solutions combined with finite rank perturbation theory allow us to obtain exact expressions for entanglement Hamiltonians. In the absence of the zero mode, the resulting entanglement Hamiltonians consist of local and bilocal terms. In the periodic sector, the presence of a zero mode leads to an additional nonlocal contribution to the entanglement Hamiltonian. We derive an exact expression for this term and for the resulting change in the entanglement entropy.

  12. Charged chiral fermions from M5-branes

    NASA Astrophysics Data System (ADS)

    Lambert, Neil; Owen, Miles

    2018-04-01

    We study M5-branes wrapped on a multi-centred Taub-NUT space. Reducing to String Theory on the S 1 fibration leads to D4-branes intersecting with D6-branes. D-braneology shows that there are additional charged chiral fermions from the open strings which stretch between the D4-branes and D6-branes. From the M-theory point of view the appearance of these charged states is mysterious as the M5-branes are wrapped on a smooth manifold. In this paper we show how these states arise in the M5-brane worldvolume theory and argue that are governed by a WZWN-like model where the topological term is five-dimensional.

  13. Issues related to the Fermion mass problem

    NASA Astrophysics Data System (ADS)

    Murakowski, Janusz Adam

    1998-09-01

    This thesis is divided into three parts. Each illustrates a different aspect of the fermion mass issue in elementary particle physics. In the first part, the possibility of chiral symmetry breaking in the presence of uniform magnetic and electric fields is investigated. The system is studied nonperturbatively with the use of basis functions compatible with the external field configuration, the parabolic cylinder functions. It is found that chiral symmetry, broken by a uniform magnetic field, is restored by electric field. Obtained result is nonperturbative in nature: even the tiniest deviation of the electric field from zero restores chiral symmetry. In the second part, heavy quarkonium systems are investigated. To study these systems, a phenomenological nonrelativistic model is built. Approximate solutions to this model are found with the use of a specially designed Pade approximation and by direct numerical integration of Schrodinger equation. The results are compared with experimental measurements of respective meson masses. Good agreement between theoretical calculations and experimental results is found. Advantages and shortcommings of the new approximation method are analysed. In the third part, an extension of the standard model of elementary particles is studied. The extension, called the aspon model, was originally introduced to cure the so called strong CP problem. In addition to fulfilling its original purpose, the aspon model modifies the couplings of the standard model quarks to the Z boson. As a result, the decay rates of the Z boson to quarks are altered. By using the recent precise measurements of the decay rates Z → bb and Z /to [/it c/=c], new constraints on the aspon model parameters are found.

  14. Mass-Selective Chiral Analysis

    NASA Astrophysics Data System (ADS)

    Boesl, Ulrich; Kartouzian, Aras

    2016-06-01

    Three ways of realizing mass-selective chiral analysis are reviewed. The first is based on the formation of diastereomers that are of homo- and hetero- type with respect to the enantiomers of involved chiral molecules. This way is quite well-established with numerous applications. The other two ways are more recent developments, both based on circular dichroism (CD). In one, conventional or nonlinear electronic CD is linked to mass spectrometry (MS) by resonance-enhanced multiphoton ionization. The other is based on CD in the angular distribution of photoelectrons, which is measured in combination with MS via photoion photoelectron coincidence. Among the many important applications of mass-selective chiral analysis, this review focuses on its use as an analytical tool for the development of heterogeneous enantioselective chemical catalysis. There exist other approaches to combine chiral analysis and mass-selective detection, such as chiral chromatography MS, which are not discussed here.

  15. Quantum phase transition of chiral Majorana fermions in the presence of disorder

    NASA Astrophysics Data System (ADS)

    Lian, Biao; Wang, Jing; Sun, Xiao-Qi; Vaezi, Abolhassan; Zhang, Shou-Cheng

    2018-03-01

    We study the quantum phase transitions of a disordered two-dimensional quantum anomalous Hall insulator with s -wave superconducting proximity, which are governed by the percolation theory of chiral Majorana fermions. Based on symmetry arguments and a renormalization-group analysis, we show there are generically two phase transitions from Bogoliubov-de Gennes Chern number N =0 to N =1 (p +i p chiral topological superconductor) and then to N =2 , in agreement with the conclusion from the band theory without disorders. Further, we discuss the critical scaling behavior of the e2/2 h conductance half plateau induced by the N =1 chiral topological superconductor recently observed in the experiment. In particular, we compare the critical behavior of the half plateau induced by the topological superconductor with that predicted recently by alternative explanations of the half plateau and show that they can be distinguished in experiments.

  16. Quantum phase transition of chiral Majorana fermions in the presence of disorder

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lian, Biao; Wang, Jing; Sun, Xiao -Qi

    Here, we study the quantum phase transitions of a disordered two-dimensional quantum anomalous Hall insulator with s-wave superconducting proximity, which are governed by the percolation theory of chiral Majorana fermions. Based on symmetry arguments and a renormalization-group analysis, we show there are generically two phase transitions from Bogoliubov–de Gennes Chern number N=0 to N=1(p+ip chiral topological superconductor) and then to N=2, in agreement with the conclusion from the band theory without disorders. Further, we discuss the critical scaling behavior of the e 2/2h conductance half plateau induced by the N=1 chiral topological superconductor recently observed in the experiment. In particular,more » we compare the critical behavior of the half plateau induced by the topological superconductor with that predicted recently by alternative explanations of the half plateau and show that they can be distinguished in experiments.« less

  17. Quantum phase transition of chiral Majorana fermions in the presence of disorder

    DOE PAGES

    Lian, Biao; Wang, Jing; Sun, Xiao -Qi; ...

    2018-03-09

    Here, we study the quantum phase transitions of a disordered two-dimensional quantum anomalous Hall insulator with s-wave superconducting proximity, which are governed by the percolation theory of chiral Majorana fermions. Based on symmetry arguments and a renormalization-group analysis, we show there are generically two phase transitions from Bogoliubov–de Gennes Chern number N=0 to N=1(p+ip chiral topological superconductor) and then to N=2, in agreement with the conclusion from the band theory without disorders. Further, we discuss the critical scaling behavior of the e 2/2h conductance half plateau induced by the N=1 chiral topological superconductor recently observed in the experiment. In particular,more » we compare the critical behavior of the half plateau induced by the topological superconductor with that predicted recently by alternative explanations of the half plateau and show that they can be distinguished in experiments.« less

  18. Itinerant quantum multicriticality of two-dimensional Dirac fermions

    NASA Astrophysics Data System (ADS)

    Roy, Bitan; Goswami, Pallab; Juričić, Vladimir

    2018-05-01

    We analyze emergent quantum multicriticality for strongly interacting, massless Dirac fermions in two spatial dimensions (d =2 ) within the framework of Gross-Neveu-Yukawa models, by considering the competing order parameters that give rise to fully gapped (insulating or superconducting) ground states. We focus only on those competing orders which can be rotated into each other by generators of an exact or emergent chiral symmetry of massless Dirac fermions, and break O(S1) and O(S2) symmetries in the ordered phase. Performing a renormalization-group analysis by using the ɛ =(3 -d ) expansion scheme, we show that all the coupling constants in the critical hyperplane flow toward a new attractive fixed point, supporting an enlarged O(S1+S2) chiral symmetry. Such a fixed point acts as an exotic quantum multicritical point (MCP), governing the continuous semimetal-insulator as well as insulator-insulator (for example, antiferromagnet to valence bond solid) quantum phase transitions. In comparison with the lower symmetric semimetal-insulator quantum critical points, possessing either O(S1) or O(S2) chiral symmetry, the MCP displays enhanced correlation length exponents, and anomalous scaling dimensions for both fermionic and bosonic fields. We discuss the scaling properties of the ratio of bosonic and fermionic masses, and the increased dc resistivity at the MCP. By computing the scaling dimensions of different local fermion bilinears in the particle-hole channel, we establish that most of the four fermion operators or generalized density-density correlation functions display faster power-law decays at the MCP compared to the free fermion and lower symmetric itinerant quantum critical points. Possible generalization of this scenario to higher-dimensional Dirac fermions is also outlined.

  19. Novel foamy origin for singlet fermion masses

    NASA Astrophysics Data System (ADS)

    Ellis, John; Mavromatos, Nick E.; Nanopoulos, Dimitri V.

    2017-10-01

    We show how masses for singlet fermions can be generated by interactions with a D-particle model of space-time foam inspired by brane theory. It has been shown previously by one of the authors (N. E. M.) that such interactions may generate dynamically small masses for charged fermions via the recoils of D-particle defects interacting with photons. In this work we consider the direct interactions of D-particle with uncharged singlet fermions such as right-handed neutrinos. Quantum fluctuations of the lattice of D-particles have massless vector (spin-one) excitations that are analogues of phonons. These mediate forces with the singlet fermions, generating large dynamical masses that may be communicated to light neutrinos via the seesaw mechanism.

  20. Fermion mass without symmetry breaking

    DOE PAGES

    Catterall, Simon

    2016-01-20

    We examine a model of reduced staggered fermions in three dimensions interacting through an SO (4) invariant four fermion interaction. The model is similar to that considered in a recent paper by Ayyer and Chandrasekharan. We present theoretical arguments and numerical evidence which support the idea that the system develops a mass gap for sufficiently strong four fermi coupling without producing a symmetry breaking fermion bilinear condensate. As a result, massless and massive phases appear to be separated by a continuous phase transition.

  1. Light quark masses with overlap fermions in quenched QCD

    NASA Astrophysics Data System (ADS)

    Giusti, L.; Hoelbling, C.; Rebbi, C.

    2001-12-01

    We present the results of a computation of the sum of the strange and average up-down quark masses with overlap fermions in the quenched approximation. Since the overlap regularization preserves chiral symmetry at finite cutoff and volume, no additive quark mass renormalization is required and the results are O(a) improved. Our simulations are performed at β=6.0 and volume V=163×32, which correspond to a lattice cutoff of ~2 GeV and to an extension of ~1.4 fm. The logarithmically divergent renormalization constant has been computed nonperturbatively in the RI/MOM scheme. By using the K-meson mass as experimental input, we obtain (ms+m)RI(2 GeV)=120(7)(21) MeV, which corresponds to mMS¯s(2 GeV)=102(6)(18) MeV if continuum perturbation theory and χPT are used. By using the Gell-Mann-Oakes-Renner relation we also obtain <ψ¯ψ>MS¯(2 GeV)/Nf =-0.0190(11)(33) GeV3=-[267(5)(15) MeV]3, where the errors are statistical and systematic respectively.

  2. SU(3) sextet model with Wilson fermions

    NASA Astrophysics Data System (ADS)

    Hansen, Martin; Pica, Claudio

    2018-03-01

    We present our final results for the SU(3) sextet model with the non-improved Wilson fermion discretization. We find evidence for several phases of the lattice model, including a bulk phase with broken chiral symmetry. We study the transition between the bulk and weak coupling phase which corresponds to a significant change in the qualitative behavior of spectral and scale setting observables. In particular the t0 and w0 observables seem to diverge in the chiral limit in the weak coupling phase. We then focus on the study of spectral observables in the chiral limit in the weak coupling phase at infinite volume. We consider the masses and decay constants for the pseudoscalar and vector mesons, the mass of the axial vector meson and the spin-1/2 baryon as a function of the quark mass, while controlling finite volume effects. We then test our data against both the IR conformal and the chirally broken hypotheses. Preprint: CP3-Origins-2017-49 DNRF90

  3. Chiral heavy fermions in a two Higgs doublet model: 750 GeV resonance or not

    NASA Astrophysics Data System (ADS)

    Bar-Shalom, Shaouly; Soni, Amarjit

    2017-03-01

    We revisit models where a heavy chiral 4th generation doublet of fermions is embedded in a class of two Higgs doublets models (2HDM) with a discrete Z2 symmetry, which couples the ;heavy; scalar doublet only to the 4th generation fermions and the ;light; one to the Standard Model (SM) fermions - the so-called 4G2HDM introduced by us several years ago. We study the constraints imposed on the 4G2HDM from direct searches of heavy fermions, from precision electroweak data (PEWD) and from the measured production and decay signals of the 125 GeV scalar, which in the 4G2HDM corresponds to the lightest CP-even scalar h. We then show that the recently reported excess in the γγ spectrum around 750 GeV can be accommodated by the heavy CP-even scalar of the 4G2HDM, H, resulting in a unique choice of parameter space: negligible mixing (sin ⁡ α ≲ O (10-3)) between the two CP-even scalars h , H and heavy 4th generation quark and lepton masses mt‧ ,mb‧ ≲ 400 GeV and mν‧ ,mτ‧ ≳ 900 GeV, respectively. Whether or not the 750 GeV γγ resonance is confirmed, interesting phenomenology emerges in q‧ - Higgs systems (q‧ =t‧ ,b‧), that can be searched for at the LHC. For example, the heavy scalar states of the model, S = H , A ,H+, may have BR (S →qbar‧q‧) ∼ O (1), giving rise to observable qbar‧q‧ signals on resonance, followed by the flavor changing q‧ decays t‧ → uh (u = u , c) and/or b‧ → dh (d = d , s , b). This leads to rather distinct signatures, with or without charged leptons, of the form qbar‧q‧ →(nj + mb + ℓW) S (j and b being light and b-quark jets, respectively), with n + m + ℓ = 6- 8 and unique kinematic features. These high jet-multiplicity signals appear to be very challenging and may need new search strategies for detection of such heavy chiral quarks. It is also shown that the flavor structure of the 4G2HDM can easily accommodate the interesting recent indications of a percent-level branching ratio in the

  4. Instantons and Massless Fermions in Two Dimensions

    DOE R&D Accomplishments Database

    Callan, C. G. Jr.; Dashen, R.; Gross, D. J.

    1977-05-01

    The role of instantons in the breakdown of chiral U(N) symmetry is studied in a two dimensional model. Chiral U(1) is always destroyed by the axial vector anomaly. For N = 2 chiral SU(N) is also spontaneously broken yielding massive fermions and three (decoupled) Goldstone bosons. For N greater than or equal to 3 the fermions remain massless. Realistic four dimensional theories are believed to behave in a similar way but the critical N above which the fermions cease to be massive is not known in four dimensions.

  5. Baryon spectrum with Nf=2+1+1 twisted mass fermions

    NASA Astrophysics Data System (ADS)

    Alexandrou, C.; Drach, V.; Jansen, K.; Kallidonis, C.; Koutsou, G.

    2014-10-01

    The masses of the low-lying baryons are evaluated using a total of ten ensembles of dynamical twisted mass fermion gauge configurations. The simulations are performed using two degenerate flavors of light quarks, and a strange and a charm quark fixed to approximately their physical values. The light sea quarks correspond to pseudo scalar masses in the range of about 210 to 430 MeV. We use the Iwasaki improved gluonic action at three values of the coupling constant corresponding to lattice spacing a=0.094, 0.082 and 0.065 fm determined from the nucleon mass. We check for both finite volume and cutoff effects on the baryon masses. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. We performed a chiral extrapolation of the forty baryon masses using SU(2) χPT. After taking the continuum limit and extrapolating to the physical pion mass our results are in good agreement with experiment. We provide predictions for the mass of the doubly charmed Ξcc*, as well as of the doubly and triply charmed Ωs that have not yet been determined experimentally.

  6. Centre vortex removal restores chiral symmetry

    NASA Astrophysics Data System (ADS)

    Trewartha, Daniel; Kamleh, Waseem; Leinweber, Derek B.

    2017-12-01

    The influence of centre vortices on dynamical chiral symmetry breaking is investigated through the light hadron spectrum on the lattice. Recent studies of the quark propagator and other quantities have provided evidence that centre vortices are the fundamental objects underpinning dynamical chiral symmetry breaking in {SU}(3) gauge theory. For the first time, we use the chiral overlap fermion action to study the low-lying hadron spectrum on lattice ensembles consisting of Monte Carlo, vortex-removed, and vortex-projected gauge fields. We find that gauge field configurations consisting solely of smoothed centre vortices are capable of reproducing all the salient features of the hadron spectrum, including dynamical chiral symmetry breaking. The hadron spectrum on vortex-removed fields shows clear signals of chiral symmetry restoration at light values of the bare quark mass, while at heavy masses the spectrum is consistent with a theory of weakly interacting constituent quarks.

  7. Resonant pairing between fermions with unequal masses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Shin-Tza; Pao, C.-H.; Yip, S.-K.

    We study via mean-field theory the pairing between fermions of different masses, especially at the unitary limit. At equal populations, the thermodynamic properties are identical with the equal mass case provided an appropriate rescaling is made. At unequal populations, for sufficiently light majority species, the system does not phase separate. For sufficiently heavy majority species, the phase separated normal phase have a density larger than that of the superfluid. For atoms in harmonic traps, the density profiles for unequal mass fermions can be drastically different from their equal-mass counterparts.

  8. Chiral anomaly enhancement and photoirradiation effects in multiband touching fermion systems

    NASA Astrophysics Data System (ADS)

    Ezawa, Motohiko

    2017-05-01

    Multiband touchings together with the emergence of fermions exhibiting linear dispersions have recently been predicted and realized in various materials. We first investigate the Adler-Bell-Jackiw chiral anomaly in these multiband touching semimetals when they are described by the pseudospin operator in high-dimensional representation. By evaluating the Chern number, we show that the anomalous Hall effect is enhanced depending on the magnitude of the pseudospin. It is also confirmed by the analysis of the Landau levels when magnetic field is applied. Namely, charge pumping occurs from one multiband touching point to another through multichannel Landau levels in the presence of parallel electric and magnetic fields. We also show a pair annihilation of two multiband touching points by photoirradiation. Furthermore, we propose generalizations of Dirac semimetals, multiple Weyl semimetals, and loop-nodal semimetals to those composed of fermions carrying pseudospins in high-dimensional representation. Finally we investigate the three-band touching protected by the C3 symmetry. We show that the three-band touching point is broken into two Weyl points by photoirradiation.

  9. Six-dimensional regularization of chiral gauge theories

    NASA Astrophysics Data System (ADS)

    Fukaya, Hidenori; Onogi, Tetsuya; Yamamoto, Shota; Yamamura, Ryo

    2017-03-01

    We propose a regularization of four-dimensional chiral gauge theories using six-dimensional Dirac fermions. In our formulation, we consider two different mass terms having domain-wall profiles in the fifth and the sixth directions, respectively. A Weyl fermion appears as a localized mode at the junction of two different domain walls. One domain wall naturally exhibits the Stora-Zumino chain of the anomaly descent equations, starting from the axial U(1) anomaly in six dimensions to the gauge anomaly in four dimensions. Another domain wall implies a similar inflow of the global anomalies. The anomaly-free condition is equivalent to requiring that the axial U(1) anomaly and the parity anomaly are canceled among the six-dimensional Dirac fermions. Since our formulation is based on a massive vector-like fermion determinant, a nonperturbative regularization will be possible on a lattice. Putting the gauge field at the four-dimensional junction and extending it to the bulk using the Yang-Mills gradient flow, as recently proposed by Grabowska and Kaplan, we define the four-dimensional path integral of the target chiral gauge theory.

  10. Centre vortex removal restores chiral symmetry

    DOE PAGES

    Trewartha, Daniel; Kamleh, Waseem; Leinweber, Derek B.

    2017-11-15

    The influence of centre vortices on dynamical chiral symmetry breaking is investigated through the light hadron spectrum on the lattice. Recent studies of the quark propagator and other quantities have provided evidence that centre vortices are the fundamental objects underpinning dynamical chiral symmetry breaking in SU(3) gauge theory. For the first time, we use the chiral overlap fermion action to study the low-lying hadron spectrum on lattice ensembles consisting of Monte Carlo, vortex-removed, and vortex-projected gauge fields. We find that gauge field configurations consisting solely of smoothed centre vortices are capable of reproducing all the salient features of the hadronmore » spectrum, including dynamical chiral symmetry breaking. In conclusion, the hadron spectrum on vortex-removed fields shows clear signals of chiral symmetry restoration at light values of the bare quark mass, while at heavy masses the spectrum is consistent with a theory of weakly-interacting constituent quarks.« less

  11. Chiral heavy fermions in a two Higgs doublet model: 750 GeV resonance or not

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bar-Shalom, Shaouly; Soni, Amarjit

    For this article, we revisit models where a heavy chiral 4th generation doublet of fermions is embedded in a class of two Higgs doublets models (2HDM) with a discrete Z 2 symmetry, which couples the “heavy” scalar doublet only to the 4th generation fermions and the “light” one to the Standard Model (SM) fermions – the so-called 4G2HDM introduced by us several years ago. We study the constraints imposed on the 4G2HDM from direct searches of heavy fermions, from precision electroweak data (PEWD) and from the measured production and decay signals of the 125 GeV scalar, which in the 4G2HDM corresponds to the lightest CP-even scalar h. We then show that the recently reported excess in the γγspectrum around 750 GeV can be accommodated by the heavy CP-even scalar of the 4G2HDM, H, resulting in a unique choice of parameter space: negligible mixing (sin α ≲ O (10 -3)) between the two CP-even scalars h, Hand heavy 4th generation quark and lepton masses m t ',m b' ≲ 400 GeV and m ν', m τ' ≳ 900 GeV, respectively. Whether or not the 750 GeV γγ resonance is confirmed, interesting phenomenology emerges in q' – Higgs systems (q' = t', b'), that can be searched for at the LHC. For example, the heavy scalar states of the model, S=H, A, H +, may have BR(S→more » $$-\\atop{q'}$$q') ~ O(1), giving rise to observable $$-\\atop{q'}$$q' signals on resonance, followed by the flavor changing q' decays t'→uh (u =u, c) and/or b'→dh (d =d, s, b). This leads to rather distinct signatures, with or without charged leptons, of the form $$-\\atop{q'}$$q'→(nj +mb +ℓW) S (j and b being light and b-quark jets, respectively), with n +m +ℓ =6–8 and unique kinematic features. These high jet-multiplicity signals appear to be very challenging and may need new search strategies for detection of such heavy chiral quarks. It is also shown that the flavor structure of the 4G2HDM can easily accommodate the interesting recent indications of a percent-level branching

  12. Chiral heavy fermions in a two Higgs doublet model: 750 GeV resonance or not

    DOE PAGES

    Bar-Shalom, Shaouly; Soni, Amarjit

    2017-03-10

    For this article, we revisit models where a heavy chiral 4th generation doublet of fermions is embedded in a class of two Higgs doublets models (2HDM) with a discrete Z 2 symmetry, which couples the “heavy” scalar doublet only to the 4th generation fermions and the “light” one to the Standard Model (SM) fermions – the so-called 4G2HDM introduced by us several years ago. We study the constraints imposed on the 4G2HDM from direct searches of heavy fermions, from precision electroweak data (PEWD) and from the measured production and decay signals of the 125 GeV scalar, which in the 4G2HDM corresponds to the lightest CP-even scalar h. We then show that the recently reported excess in the γγspectrum around 750 GeV can be accommodated by the heavy CP-even scalar of the 4G2HDM, H, resulting in a unique choice of parameter space: negligible mixing (sin α ≲ O (10 -3)) between the two CP-even scalars h, Hand heavy 4th generation quark and lepton masses m t ',m b' ≲ 400 GeV and m ν', m τ' ≳ 900 GeV, respectively. Whether or not the 750 GeV γγ resonance is confirmed, interesting phenomenology emerges in q' – Higgs systems (q' = t', b'), that can be searched for at the LHC. For example, the heavy scalar states of the model, S=H, A, H +, may have BR(S→more » $$-\\atop{q'}$$q') ~ O(1), giving rise to observable $$-\\atop{q'}$$q' signals on resonance, followed by the flavor changing q' decays t'→uh (u =u, c) and/or b'→dh (d =d, s, b). This leads to rather distinct signatures, with or without charged leptons, of the form $$-\\atop{q'}$$q'→(nj +mb +ℓW) S (j and b being light and b-quark jets, respectively), with n +m +ℓ =6–8 and unique kinematic features. These high jet-multiplicity signals appear to be very challenging and may need new search strategies for detection of such heavy chiral quarks. It is also shown that the flavor structure of the 4G2HDM can easily accommodate the interesting recent indications of a percent-level branching

  13. Hadron spectroscopy with dynamical chirally improved fermions

    NASA Astrophysics Data System (ADS)

    Gattringer, Christof; Hagen, Christian; Lang, C. B.; Limmer, Markus; Mohler, Daniel; Schäfer, Andreas

    2009-03-01

    We simulate two dynamical, mass-degenerate light quarks on 163×32 lattices with a spatial extent of 2.4 fm using the chirally improved Dirac operator. The simulation method, the implementation of the action, and signals of equilibration are discussed in detail. Based on the eigenvalues of the Dirac operator we discuss some qualitative features of our approach. Results for ground-state masses of pseudoscalar and vector mesons as well as for the nucleon and delta baryons are presented.

  14. Domain wall fermion and CP symmetry breaking

    NASA Astrophysics Data System (ADS)

    Fujikawa, Kazuo; Suzuki, Hiroshi

    2003-02-01

    We examine the CP properties of chiral gauge theory defined by a formulation of the domain wall fermion, where the light field variables q and q¯ together with Pauli-Villars fields Q and Q¯ are utilized. It is shown that this domain wall representation in the infinite flavor limit N=∞ is valid only in the topologically trivial sector, and that the conflict among lattice chiral symmetry, strict locality and CP symmetry still persists for finite lattice spacing a. The CP transformation generally sends one representation of lattice chiral gauge theory into another representation of lattice chiral gauge theory, resulting in the inevitable change of propagators. A modified form of lattice CP transformation motivated by the domain wall fermion, which keeps the chiral action in terms of the Ginsparg-Wilson fermion invariant, is analyzed in detail; this provides an alternative way to understand the breaking of CP symmetry at least in the topologically trivial sector. We note that the conflict with CP symmetry could be regarded as a topological obstruction. We also discuss the issues related to the definition of Majorana fermions in connection with the supersymmetric Wess-Zumino model on the lattice.

  15. Quenched results for light quark physics with overlap fermions

    NASA Astrophysics Data System (ADS)

    Giusti, L.; Hoelbling, C.; Rebbi, C.

    2002-03-01

    We present results of a quenched QCD simulation with overlap fermions on a lattice of volume V = 16 3 × 32 at β = 6.0, which corresponds to a lattice cutoff of ⋍ 2 GeV and an extension of ⋍ 1.4 fm. From the two-point correlation functions of bilinear operators we extract the pseudoscalar meson masses and the corresponding decay constants. From the GMOR relation we determine the chiral condensate and, by using the K-meson mass as experimental input, we compute the sum of the strange and average up-down quark masses ( m s + overlinem). The needed logarithmic divergent renormalization constant Z S is computed with the RI/MOM non-perturbative renormalization technique. Since the overlap preserves chiral symmetry at finite cutoff and volume, no divergent quark mass and chiral condensate additive renormalizations are required and the results are O( a) improved.

  16. Fermion masses in SO(10)

    NASA Astrophysics Data System (ADS)

    Jungman, Gerard

    1992-11-01

    Yukawa-coupling-constant unification together with the known fermion masses is used to constrain SO(10) models. We consider the case of one (heavy) generation, with the tree-level relation mb=mτ, calculating the limits on the intermediate scales due to the known limits on fermion masses. This analysis extends previous analyses which addressed only the simplest symmetry-breaking schemes. In the case where the low-energy model is the standard model with one Higgs doublet, there are very strong constraints due to the known limits on the top-quark mass and the τ-neutrino mass. The two-Higgs-doublet case is less constrained, though we can make progress in constraining this model also. We identify those parameters to which the viability of the model is most sensitive. We also discuss the ``triviality'' bounds on mt obtained from the analysis of the Yukawa renormalization-group equations. Finally we address the role of a speculative constraint on the τ-neutrino mass, arising from the cosmological implications of anomalous B+L violation in the early Universe.

  17. Effective action and electromagnetic response of topological superconductors and Majorana-mass Weyl fermions

    NASA Astrophysics Data System (ADS)

    Stone, Michael; Lopes, Pedro L. e. S.

    2016-05-01

    Motivated by an apparent paradox in [X.-L. Qi, E. Witten, and S.-C. Zhang, Phys. Rev. B 87, 134519 (2013), 10.1103/PhysRevB.87.134519], we use the method of gauged Wess-Zumino-Witten functionals to construct an effective action for a Weyl fermion with a Majorana mass that arises from coupling to a charged condensate. We obtain expressions for the current induced by an external gauge field and observe that the topological part of the current is only one-third of that that might have been expected from the gauge anomaly. The anomaly is not changed by the induced mass gap, however. The topological current is supplemented by a conventional supercurrent that provides the remaining two-thirds of the anomaly once the equation of motion for the Goldstone mode is satisfied. We apply our formula for the current to resolve the apparent paradox and also to the chiral magnetic effect (CME), where it predicts a reduction of the CME current to one-third of its value for a free Weyl gas in thermal equilibrium. We attribute this reduction to a partial cancellation of the CME by a chiral vortical effect current arising from the persistent rotation of the fluid induced by the external magnetic field.

  18. Wigner functions for fermions in strong magnetic fields

    NASA Astrophysics Data System (ADS)

    Sheng, Xin-li; Rischke, Dirk H.; Vasak, David; Wang, Qun

    2018-02-01

    We compute the covariant Wigner function for spin-(1/2) fermions in an arbitrarily strong magnetic field by exactly solving the Dirac equation at non-zero fermion-number and chiral-charge densities. The Landau energy levels as well as a set of orthonormal eigenfunctions are found as solutions of the Dirac equation. With these orthonormal eigenfunctions we construct the fermion field operators and the corresponding Wigner-function operator. The Wigner function is obtained by taking the ensemble average of the Wigner-function operator in global thermodynamical equilibrium, i.e., at constant temperature T and non-zero fermion-number and chiral-charge chemical potentials μ and μ_5, respectively. Extracting the vector and axial-vector components of the Wigner function, we reproduce the currents of the chiral magnetic and separation effect in an arbitrarily strong magnetic field.

  19. Patterns of symmetry breaking in chiral QCD

    NASA Astrophysics Data System (ADS)

    Bolognesi, Stefano; Konishi, Kenichi; Shifman, Mikhail

    2018-05-01

    We consider S U (N ) Yang-Mills theory with massless chiral fermions in a complex representation of the gauge group. The main emphasis is on the so-called hybrid ψ χ η model. The possible patterns of realization of the continuous chiral flavor symmetry are discussed. We argue that the chiral symmetry is broken in conjunction with a dynamical Higgsing of the gauge group (complete or partial) by bifermion condensates. As a result a color-flavor locked symmetry is preserved. The 't Hooft anomaly matching proceeds via saturation of triangles by massless composite fermions or, in a mixed mode, i.e. also by the "weakly" coupled fermions associated with dynamical Abelianization, supplemented by a number of Nambu-Goldstone mesons. Gauge-singlet condensates are of the multifermion type and, though it cannot be excluded, the chiral symmetry realization via such gauge invariant condensates is more contrived (requires a number of four-fermion condensates simultaneously and, even so, problems remain) and less plausible. We conclude that in the model at hand, chiral flavor symmetry implies dynamical Higgsing by bifermion condensates.

  20. Chiral sp-orbital paired superfluid of fermionic atoms in a 2D spin-dependent optical lattice

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Li, Xiaopeng; Wu, Biao; Liu, W. Vincent

    2014-03-01

    Recent progress in realizing synthetic quantum orbital materials in chequerboard and hexagonal optical lattices opens an avenue towards exploiting unconventional quantum states, advancing our understanding of correlated quantum matter. Here, we unveil a chiral sp -orbital paired superfluid state for an interacting two-component Fermi gas in a 2D spin-dependent optical lattice. Surprisingly, this novel state is found to exist in a wide regime of experimentally tunable interaction strengths. The coexistence of this chiral superfluid and the ferro-orbital order is reminiscent of that of magnetism and superconductivity which is a long-standing issue in condensed matter physics. The topological properties are demonstrated by the existence of gapless chiral fermions in the presence of domain wall defects, reminiscent of quantum Hall edge states. Such properties can be measured by radio frequency spectroscopy in cold atomic experiments. Work supported in part by U.S. ARO, AFOSR, and DARPA-OLE-ARO, Kaufman Foundation, and NSF of China.

  1. Lattice fermions

    NASA Technical Reports Server (NTRS)

    Wilczek, Frank

    1987-01-01

    A simple heuristic proof of the Nielsen-Ninomaya theorem is given. A method is proposed whereby the multiplication of fermion species on a lattice is reduced to the minimal doubling, in any dimension, with retention of appropriate chiral symmetries. Also, it is suggested that use of spatially thinned fermion fields is likely to be a useful and appropriate approximation in QCD - in any case, it is a self-checking one.

  2. Dark matter and neutrino mass from the smallest non-Abelian chiral dark sector

    NASA Astrophysics Data System (ADS)

    Berryman, Jeffrey M.; de Gouvêa, André; Kelly, Kevin J.; Zhang, Yue

    2017-10-01

    All pieces of concrete evidence for phenomena outside the standard model (SM)—neutrino masses and dark matter—are consistent with the existence of new degrees of freedom that interact very weakly, if at all, with those in the SM. We propose that these new degrees of freedom organize themselves into a simple dark sector, a chiral S U (3 )×S U (2 ) gauge theory with the smallest nontrivial fermion content. Similar to the SM, the dark S U (2 ) is spontaneously broken while the dark S U (3 ) confines at low energies. At the renormalizable level, the dark sector contains massless fermions—dark leptons—and stable massive particles—dark protons. We find that dark protons with masses between 10 and 100 TeV satisfy all current cosmological and astrophysical observations concerning dark matter even if dark protons are a symmetric thermal relic. The dark leptons play the role of right-handed neutrinos and allow simple realizations of the seesaw mechanism or the possibility that neutrinos are Dirac fermions. In the latter case, neutrino masses are also parametrically different from charged-fermion masses and the lightest neutrino is predicted to be massless. Since the new "neutrino" and "dark-matter" degrees of freedom interact with one another, these two new-physics phenomena are intertwined. Dark leptons play a nontrivial role in early Universe cosmology while indirect searches for dark matter involve, decisively, dark-matter annihilations into dark leptons. These, in turn, may lead to observable signatures at high-energy neutrino and gamma-ray observatories, especially once one accounts for the potential Sommerfeld enhancement of the annihilation cross section, derived from the low-energy dark-sector effective theory, a possibility we explore quantitatively in some detail.

  3. Interface and phase transition between Moore-Read and Halperin 331 fractional quantum Hall states: Realization of chiral Majorana fermion

    NASA Astrophysics Data System (ADS)

    Yang, Kun

    2017-12-01

    We consider an interface separating the Moore-Read state and Halperin 331 state in a half-filled Landau level, which can be realized in a double quantum well system with varying interwell tunneling and/or interaction strengths. In the presence of electron tunneling and strong Coulomb interactions across the interface, we find that all charge modes localize and the only propagating mode left is a chiral Majorana fermion mode. Methods to probe this neutral mode are proposed. A quantum phase transition between the Moore-Read and Halperin 331 states is described by a network of such Majorana fermion modes. In addition to a direct transition, they may also be separated by a phase in which the Majorana fermions are delocalized, realizing an incompressible state which exhibits quantum Hall charge transport and bulk heat conduction.

  4. Convergence of the chiral expansion in two-flavor lattice QCD.

    PubMed

    Noaki, J; Aoki, S; Chiu, T W; Fukaya, H; Hashimoto, S; Hsieh, T H; Kaneko, T; Matsufuru, H; Onogi, T; Shintani, E; Yamada, N

    2008-11-14

    We test the convergence property of the chiral perturbation theory using a lattice QCD calculation of pion mass and decay constant with two dynamical quark flavors. The lattice calculation is performed using the overlap fermion formulation, which realizes exact chiral symmetry at finite lattice spacing. By comparing various expansion prescriptions, we find that the chiral expansion is well saturated at the next-to-leading order for pions lighter than approximately 450 MeV. Better convergence behavior is found, in particular, for a resummed expansion parameter xi, with which the lattice data in the pion mass region 290-750 MeV can be fitted well with the next-to-next-to-leading order formulas. We obtain the results in two-flavor QCD for the low energy constants l[over ]_{3} and l[over ]_{4} as well as the pion decay constant, the chiral condensate, and the average up and down quark mass.

  5. Chiral current generation in QED by longitudinal photons

    NASA Astrophysics Data System (ADS)

    Acosta Avalo, J. L.; Pérez Rojas, H.

    2016-08-01

    We report the generation of a pseudovector electric current having imbalanced chirality in an electron-positron strongly magnetized gas in QED. It propagates along the external applied magnetic field B as a chiral magnetic effect in QED. It is triggered by a perturbative electric field parallel to B, associated to a pseudovector longitudinal mode propagating along B. An electromagnetic chemical potential was introduced, but our results remain valid even when it vanishes. A nonzero fermion mass was assumed, which is usually considered vanishing in the literature. In the quantum field theory formalism at finite temperature and density, an anomaly relation for the axial current was found for a medium of massive fermions. It bears some analogy to the Adler-Bell-Jackiw anomaly. From the expression for the chiral current in terms of the photon self-energy tensor in a medium, it is obtained that electrons and positrons scattered by longitudinal photons (inside the light cone) contribute to the chiral current, as well as the to pair creation due to longitudinal photons (out of light cone). In the static limit, an electric pseudovector current is obtained in the lowest Landau level.

  6. Staggered chiral perturbation theory at next-to-leading order

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sharpe, Stephen R.; Van de Water, Ruth S.

    2005-06-01

    We study taste and Euclidean rotational symmetry violation for staggered fermions at nonzero lattice spacing using staggered chiral perturbation theory. We extend the staggered chiral Lagrangian to O(a{sup 2}p{sup 2}), O(a{sup 4}), and O(a{sup 2}m), the orders necessary for a full next-to-leading order calculation of pseudo-Goldstone boson masses and decay constants including analytic terms. We then calculate a number of SO(4) taste-breaking quantities, which involve only a small subset of these next-to-leading order operators. We predict relationships between SO(4) taste-breaking splittings in masses, pseudoscalar decay constants, and dispersion relations. We also find predictions for a few quantities that are notmore » SO(4) breaking. All these results hold also for theories in which the fourth root of the fermionic determinant is taken to reduce the number of quark tastes; testing them will therefore provide evidence for or against the validity of this trick.« less

  7. Fermionic extensions of the Standard Model in light of the Higgs couplings

    NASA Astrophysics Data System (ADS)

    Bizot, Nicolas; Frigerio, Michele

    2016-01-01

    As the Higgs boson properties settle, the constraints on the Standard Model extensions tighten. We consider all possible new fermions that can couple to the Higgs, inspecting sets of up to four chiral multiplets. We confront them with direct collider searches, electroweak precision tests, and current knowledge of the Higgs couplings. The focus is on scenarios that may depart from the decoupling limit of very large masses and vanishing mixing, as they offer the best prospects for detection. We identify exotic chiral families that may receive a mass from the Higgs only, still in agreement with the hγγ signal strength. A mixing θ between the Standard Model and non-chiral fermions induces order θ 2 deviations in the Higgs couplings. The mixing can be as large as θ ˜ 0 .5 in case of custodial protection of the Z couplings or accidental cancellation in the oblique parameters. We also notice some intriguing effects for much smaller values of θ, especially in the lepton sector. Our survey includes a number of unconventional pairs of vector-like and Majorana fermions coupled through the Higgs, that may induce order one corrections to the Higgs radiative couplings. We single out the regions of parameters where hγγ and hgg are unaffected, while the hγZ signal strength is significantly modified, turning a few times larger than in the Standard Model in two cases. The second run of the LHC will effectively test most of these scenarios.

  8. Chiral anomaly, Berry phase, and chiral kinetic theory from worldlines in quantum field theory

    DOE PAGES

    Mueller, Niklas; Venugopalan, Raju

    2018-03-21

    Here, we outline a novel chiral kinetic theory framework for systematic computations of the Chiral Magnetic Effect (CME) in ultrarelativistic heavy-ion collisions. The real part of the fermion determinant in the QCD effective action is expressed as a supersymmetric world-line action of spinning, colored, Grassmanian point particles in background gauge fields, with equations of motion that are covariant generalizations of the Bargmann-Michel-Telegdi and Wong equations. Berry’s phase is obtained in a consistent non-relativistic adiabatic limit. The chiral anomaly, in contrast, arises from the phase of the fermion determinant; its topological properties are therefore distinct from those of the Berry phase.more » We show that the imaginary contribution to the fermion determinant too can be expressed as a point particle world-line path integral and derive the corresponding anomalous axial vector current. Our results can be used to derive a covariant relativistic chiral kinetic theory including the effects of topological fluctuations that has overlap with classical-statistical simulations of the CME at early times and anomalous hydrodynamics at late times.« less

  9. Chiral anomaly, Berry phase, and chiral kinetic theory from worldlines in quantum field theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mueller, Niklas; Venugopalan, Raju

    Here, we outline a novel chiral kinetic theory framework for systematic computations of the Chiral Magnetic Effect (CME) in ultrarelativistic heavy-ion collisions. The real part of the fermion determinant in the QCD effective action is expressed as a supersymmetric world-line action of spinning, colored, Grassmanian point particles in background gauge fields, with equations of motion that are covariant generalizations of the Bargmann-Michel-Telegdi and Wong equations. Berry’s phase is obtained in a consistent non-relativistic adiabatic limit. The chiral anomaly, in contrast, arises from the phase of the fermion determinant; its topological properties are therefore distinct from those of the Berry phase.more » We show that the imaginary contribution to the fermion determinant too can be expressed as a point particle world-line path integral and derive the corresponding anomalous axial vector current. Our results can be used to derive a covariant relativistic chiral kinetic theory including the effects of topological fluctuations that has overlap with classical-statistical simulations of the CME at early times and anomalous hydrodynamics at late times.« less

  10. Chiral anomaly, Berry phase, and chiral kinetic theory from worldlines in quantum field theory

    NASA Astrophysics Data System (ADS)

    Mueller, Niklas; Venugopalan, Raju

    2018-03-01

    In previous work, we outlined a worldline framework that can be used for systematic computations of the chiral magnetic effect (CME) in ultrarelativistic heavy-ion collisions. Towards this end, we first expressed the real part of the fermion determinant in the QCD effective action as a supersymmetric worldline action of spinning, colored, Grassmanian point particles in background gauge fields, with equations of motion that are covariant generalizations of the Bargmann-Michel-Telegdi and Wong equations. The chiral anomaly, in contrast, arises from the phase of the fermion determinant. Remarkably, the latter too can be expressed as a point particle worldline path integral, which can be employed to derive the anomalous axial vector current. We will show here how Berry's phase can be obtained in a consistent nonrelativistic adiabatic limit of the real part of the fermion determinant. Our work provides a general first principles demonstration that the topology of Berry's phase is distinct from that of the chiral anomaly confirming prior arguments by Fujikawa in specific contexts. This suggests that chiral kinetic treatments of the CME in heavy-ion collisions that include Berry's phase alone are incomplete. We outline the elements of a worldline covariant relativistic chiral kinetic theory that captures the physics of how the chiral current is modified by many-body scattering and topological fluctuations.

  11. Fermion Cooper pairing with unequal masses: Standard field theory approach

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    He Lianyi; Jin Meng; Zhuang Pengfei

    Fermion Cooper pairing with unequal masses is investigated in a standard field theory approach. We derived the superfluid density and Meissner mass squared of the U(1) gauge field in a general two-species model and found that the often used proportional relation between the two quantities is broken when the fermion masses are unequal. In the weak-coupling region, the superfluid density is always negative but the Meissner mass squared becomes mostly positive when the mass ratio between the pairing fermions is large enough. We established a proper momentum configuration of the LOFF pairing with unequal masses and showed that the LOFFmore » state is energetically favored due to the negative superfluid density. The single-plane-wave LOFF state is physically equivalent to an anisotropic state with a spontaneously generated superflow. The extension to a finite-range interaction is briefly discussed.« less

  12. Chiral magnetic effect in lattice QCD with a chiral chemical potential.

    PubMed

    Yamamoto, Arata

    2011-07-15

    We perform a first lattice QCD simulation including a two-flavor dynamical fermion with a chiral chemical potential. Because the chiral chemical potential gives rise to no sign problem, we can exactly analyze a chirally imbalanced QCD matter by Monte Carlo simulation. By applying an external magnetic field to this system, we obtain a finite induced current along the magnetic field, which corresponds to the chiral magnetic effect. The obtained induced current is proportional to the magnetic field and to the chiral chemical potential, which is consistent with an analytical prediction.

  13. The Möbius domain wall fermion algorithm

    NASA Astrophysics Data System (ADS)

    Brower, Richard C.; Neff, Harmut; Orginos, Kostas

    2017-11-01

    We present a review of the properties of generalized domain wall Fermions, based on a (real) Möbius transformation on the Wilson overlap kernel, discussing their algorithmic efficiency, the degree of explicit chiral violations measured by the residual mass (mres) and the Ward-Takahashi identities. The Möbius class interpolates between Shamir's domain wall operator and Boriçi's domain wall implementation of Neuberger's overlap operator without increasing the number of Dirac applications per conjugate gradient iteration. A new scaling parameter (α) reduces chiral violations at finite fifth dimension (Ls) but yields exactly the same overlap action in the limit Ls → ∞. Through the use of 4d Red/Black preconditioning and optimal tuning for the scaling α(Ls) , we show that chiral symmetry violations are typically reduced by an order of magnitude at fixed Ls. We argue that the residual mass for a tuned Möbius algorithm with α = O(1 /Lsγ) for γ < 1 will eventually fall asymptotically as mres = O(1 /Ls1+γ) in the case of a 5D Hamiltonian with out a spectral gap.

  14. The Mobius domain wall fermion algorithm

    DOE PAGES

    Brower, Richard C.; Neff, Harmut; Orginos, Kostas

    2017-07-22

    We present a review of the properties of generalized domain wall Fermions, based on a (real) Möbius transformation on the Wilson overlap kernel, discussing their algorithmic efficiency, the degree of explicit chiral violations measured by the residual mass (m res) and the Ward–Takahashi identities. The Möbius class interpolates between Shamir’s domain wall operator and Boriçi’s domain wall implementation of Neuberger’s overlap operator without increasing the number of Dirac applications per conjugate gradient iteration. A new scaling parameter (α) reduces chiral violations at finite fifth dimension (L s) but yields exactly the same overlap action in the limit L s →more » ∞ . Through the use of 4d Red/Black preconditioning and optimal tuning for the scaling α(L s), we show that chiral symmetry violations are typically reduced by an order of magnitude at fixed Ls . Here, we argue that the residual mass for a tuned Möbius algorithm with α = O(1/L s γ) for γ < 1 will eventually fall asymptotically as m res = O(1/L s 1+γ) in the case of a 5D Hamiltonian with out a spectral gap.« less

  15. The Mobius domain wall fermion algorithm

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brower, Richard C.; Neff, Harmut; Orginos, Kostas

    We present a review of the properties of generalized domain wall Fermions, based on a (real) Möbius transformation on the Wilson overlap kernel, discussing their algorithmic efficiency, the degree of explicit chiral violations measured by the residual mass (m res) and the Ward–Takahashi identities. The Möbius class interpolates between Shamir’s domain wall operator and Boriçi’s domain wall implementation of Neuberger’s overlap operator without increasing the number of Dirac applications per conjugate gradient iteration. A new scaling parameter (α) reduces chiral violations at finite fifth dimension (L s) but yields exactly the same overlap action in the limit L s →more » ∞ . Through the use of 4d Red/Black preconditioning and optimal tuning for the scaling α(L s), we show that chiral symmetry violations are typically reduced by an order of magnitude at fixed Ls . Here, we argue that the residual mass for a tuned Möbius algorithm with α = O(1/L s γ) for γ < 1 will eventually fall asymptotically as m res = O(1/L s 1+γ) in the case of a 5D Hamiltonian with out a spectral gap.« less

  16. Lattice QCD with two dynamical flavors of domain wall fermions

    NASA Astrophysics Data System (ADS)

    Aoki, Y.; Blum, T.; Christ, N.; Dawson, C.; Hashimoto, K.; Izubuchi, T.; Laiho, J. W.; Levkova, L.; Lin, M.; Mawhinney, R.; Noaki, J.; Ohta, S.; Orginos, K.; Soni, A.

    2005-12-01

    We present results from the first large-scale study of two-flavor QCD using domain wall fermions (DWF), a chirally symmetric fermion formulation which has been proven to be very effective in the quenched approximation. We work on lattices of size 163×32, with a lattice cutoff of a-1≈1.7GeV and dynamical (or sea) quark masses in the range mstrange/2≲msea≲mstrange. After discussing the algorithmic and implementation issues involved in simulating dynamical DWF, we report on the low-lying hadron spectrum, decay constants, static quark potential, and the important kaon weak matrix element describing indirect CP violation in the standard model, BK. In the latter case we include the effect of nondegenerate quark masses (ms≠mu=md), finding BKM Smacr (2GeV)=0.495(18).

  17. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP ENTITLED - DOMAIN WALL FERMIONS AT TEN YEARS (VOLUME 84)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    BLUM,T.; SONI,A.

    The workshop was held to mark the 10th anniversary of the first numerical simulations of QCD using domain wall fermions initiated at BNL. It is very gratifying that in the intervening decade widespread use of domain wall and overlap fermions is being made. It therefore seemed appropriate at this stage for some ''communal introspection'' of the progress that has been made, hurdles that need to be overcome, and physics that can and should be done with chiral fermions. The meeting was very well attended, drawing about 60 registered participants primarily from Europe, Japan and the US. It was quite remarkablemore » that pioneers David Kaplan, Herbert Neuberger, Rajamani Narayanan, Yigal Shamir, Sinya Aoki, and Pavlos Vranas all attended the workshop. Comparisons between domain wall and overlap formulations, with their respective advantages and limitations, were discussed at length, and a broad physics program including pion and kaon physics, the epsilon regime, nucleon structure, and topology, among others, emerged. New machines and improved algorithms have played a key role in realizing realistic dynamical fermion lattice simulations (small quark mass, large volume, and so on), so much in fact that measurements are now as costly. Consequently, ways to make the measurements more efficient were also discussed. We were very pleased to see the keen and ever growing interest in chiral fermions in our community and the significant strides our colleagues have made in bringing chiral fermions to the fore of lattice QCD calculations. Their contributions made the workshop a success, and we thank them deeply for sharing their time and ideas. Finally, we must especially acknowledge Norman Christ and Bob Mawhinney for their early and continued collaboration without which the success of domain wall fermions would not have been possible.« less

  18. BCS to BEC evolution for mixtures of fermions with unequal masses

    NASA Astrophysics Data System (ADS)

    de Melo, Carlos A. R. Sa

    2009-03-01

    I discuss the zero and finite temperature phase diagrams of a mixture of fermions with unequal masses with and without population imbalance, which may correspond for example to mixtures of ^6Li and ^40K, ^6Li and ^87Sr, or ^40K and ^87Sr in the context of ultracold atoms. At zero temperature and when excess fermions are present, at least three phases may occur as the interaction parameter is changed from the BCS to the BEC regime. These phases correspond to normal, phase separation, or superfluid with coexistence between paired and excess fermions. The zero temperature phase diagram of population imbalance versus interaction parameter presents a remarkable asymmetry between the cases involving excess lighter or heavier fermions [1, 2], in sharp contrast with the symmetric phase diagram corresponding to the case of equal masses. At finite temperatures, the phase separation region of the phase diagram competes with superfluid regions possessing gapless elementary excitations [3] for certain ranges of the interaction parameter depending on the mass ratio. Furthermore, a phase transition may take place between two superfluid phases which are topologically distinct. The precise location of such transition is sensitive to the mass ratio between the two species of fermions. Signatures of this possible topological transition are present in the momentum distribution or structure factor, which may be measured experimentally in time-of-flight or through Bragg scattering, respectively. Lastly, throughout the evolution from BCS to BEC, I discuss the critical current and sound velocity for unequal mass systems as a function of interaction parameter and mass ratio. These quantities may also be measured via the same techniques already used in mixtures of fermions with equal masses. [1] M. Iskin, and C. A. R. Sa de Melo, Phys. Rev. Lett. 97, 100404 (2006). [2] M. Iskin and C. A. R. Sa de Melo, Phys. Rev. A 76, 013601 (2007). [3] Li Han, and C. A. R. Sa de Melo, arXiv:0812.xxxx

  19. Calculation of K →π π decay amplitudes with improved Wilson fermion action in lattice QCD

    NASA Astrophysics Data System (ADS)

    Ishizuka, N.; Ishikawa, K.-I.; Ukawa, A.; Yoshié, T.

    2015-10-01

    We present our result for the K →π π decay amplitudes for both the Δ I =1 /2 and 3 /2 processes with the improved Wilson fermion action. Expanding on the earlier works by Bernard et al. and by Donini et al., we show that mixings with four-fermion operators with wrong chirality are absent even for the Wilson fermion action for the parity odd process in both channels due to CPS symmetry. Therefore, after subtraction of an effect from the lower dimensional operator, a calculation of the decay amplitudes is possible without complications from operators with wrong chirality, as for the case with chirally symmetric lattice actions. As a first step to verify the possibility of calculations with the Wilson fermion action, we consider the decay amplitudes at an unphysical quark mass mK˜2 mπ . Our calculations are carried out with Nf=2 +1 gauge configurations generated with the Iwasaki gauge action and nonperturbatively O (a )-improved Wilson fermion action at a =0.091 fm , mπ=280 MeV , and mK=580 MeV on a 323×64 (L a =2.9 fm ) lattice. For the quark loops in the penguin and disconnected contributions in the I =0 channel, the combined hopping parameter expansion and truncated solver method work very well for variance reduction. We obtain, for the first time with a Wilson-type fermion action, that Re A0=60 (36 )×1 0-8 GeV and Im A0=-67 (56 )×1 0-12 GeV for a matching scale q*=1 /a . The dependence on the matching scale q* for these values is weak.

  20. Chiral tunneling in a twisted graphene bilayer.

    PubMed

    He, Wen-Yu; Chu, Zhao-Dong; He, Lin

    2013-08-09

    The perfect transmission in a graphene monolayer and the perfect reflection in a Bernal graphene bilayer for electrons incident in the normal direction of a potential barrier are viewed as two incarnations of the Klein paradox. Here we show a new and unique incarnation of the Klein paradox. Owing to the different chiralities of the quasiparticles involved, the chiral fermions in a twisted graphene bilayer show an adjustable probability of chiral tunneling for normal incidence: they can be changed from perfect tunneling to partial or perfect reflection, or vice versa, by controlling either the height of the barrier or the incident energy. As well as addressing basic physics about how the chiral fermions with different chiralities tunnel through a barrier, our results provide a facile route to tune the electronic properties of the twisted graphene bilayer.

  1. Mobius domain-wall fermions on gradient-flowed dynamical HISQ ensembles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Berkowitz, Evan; Bouchard, Chris; Chang, Chia Cheng

    Here, we report on salient features of a mixed lattice QCD action using valence M\\"{o}bius domain-wall fermions solved on the dynamicalmore » $$N_f=2+1+1$$ HISQ ensembles generated by the MILC Collaboration. The approximate chiral symmetry properties of the valence fermions are shown to be significantly improved by utilizing the gradient-flow scheme to first smear the HISQ configurations. The greater numerical cost of the M\\"{o}bius domain-wall inversions is mitigated by the highly efficient QUDA library optimized for NVIDIA GPU accelerated compute nodes. We have created an interface to this optimized QUDA solver in Chroma. We provide tuned parameters of the action and performance of QUDA using ensembles with the lattice spacings $$a \\simeq \\{0.15, 0.12, 0.09\\}$$ fm and pion masses $$m_\\pi \\simeq \\{310, 220,130\\}$$ MeV. We have additionally generated two new ensembles with $$a\\sim0.12$$ fm and $$m_\\pi\\sim\\{400, 350\\}$$ MeV. With a fixed flow-time of $$t_{gf}=1$$ in lattice units, the residual chiral symmetry breaking of the valence fermions is kept below 10\\% of the light quark mass on all ensembles, $$m_{res} \\lesssim 0.1\\times m_l$$, with moderate values of the fifth dimension $$L_5$$ and a domain-wall height $$M_5 \\leq 1.3$$. As a benchmark calculation, we perform a continuum, infinite volume, physical pion and kaon mass extrapolation of $$F_{K^\\pm}/F_{\\pi^\\pm}$$ and demonstrate our results are independent of flow-time, and consistent with the FLAG determination of this quantity at the level of less than one standard deviation.« less

  2. Mobius domain-wall fermions on gradient-flowed dynamical HISQ ensembles

    DOE PAGES

    Berkowitz, Evan; Bouchard, Chris; Chang, Chia Cheng; ...

    2017-09-25

    Here, we report on salient features of a mixed lattice QCD action using valence M\\"{o}bius domain-wall fermions solved on the dynamicalmore » $$N_f=2+1+1$$ HISQ ensembles generated by the MILC Collaboration. The approximate chiral symmetry properties of the valence fermions are shown to be significantly improved by utilizing the gradient-flow scheme to first smear the HISQ configurations. The greater numerical cost of the M\\"{o}bius domain-wall inversions is mitigated by the highly efficient QUDA library optimized for NVIDIA GPU accelerated compute nodes. We have created an interface to this optimized QUDA solver in Chroma. We provide tuned parameters of the action and performance of QUDA using ensembles with the lattice spacings $$a \\simeq \\{0.15, 0.12, 0.09\\}$$ fm and pion masses $$m_\\pi \\simeq \\{310, 220,130\\}$$ MeV. We have additionally generated two new ensembles with $$a\\sim0.12$$ fm and $$m_\\pi\\sim\\{400, 350\\}$$ MeV. With a fixed flow-time of $$t_{gf}=1$$ in lattice units, the residual chiral symmetry breaking of the valence fermions is kept below 10\\% of the light quark mass on all ensembles, $$m_{res} \\lesssim 0.1\\times m_l$$, with moderate values of the fifth dimension $$L_5$$ and a domain-wall height $$M_5 \\leq 1.3$$. As a benchmark calculation, we perform a continuum, infinite volume, physical pion and kaon mass extrapolation of $$F_{K^\\pm}/F_{\\pi^\\pm}$$ and demonstrate our results are independent of flow-time, and consistent with the FLAG determination of this quantity at the level of less than one standard deviation.« less

  3. Topological susceptibility of QCD with dynamical Möbius domain-wall fermions

    NASA Astrophysics Data System (ADS)

    Aoki, S.; Cossu, G.; Fukaya, H.; Hashimoto, S.; Kaneko, T.

    2018-04-01

    We compute the topological susceptibility χ_t of lattice QCD with 2+1 dynamical quark flavors described by the Möbius domain-wall fermion. Violation of chiral symmetry as measured by the residual mass is kept at ˜1 MeV or smaller. We measure the fluctuation of the topological charge density in a "slab" sub-volume of the simulated lattice using the method proposed by W. Bietenholz, P. de Forcrand, and U. Gerber, J. High Energy Phys. 12, 070 (2015) and W. Bietenholz, K. Cichy, P. de Forcrand, A. Dromard, and U. Gerber, PoS LATTICE 2016, 321 (2016). The quark mass dependence of χ_t is consistent with the prediction of chiral perturbation theory, from which the chiral condensate is extracted as Σ^{\\overlineMS}(2 GeV) = [274(13)(29) MeV]^3, where the first error is statistical and the second one is systematic. Combining the results for the pion mass M_π and decay constant F_π, we obtain χ_t = 0.229(03)(13)M_π^2F_π^2 at the physical point.

  4. Quark chiral condensate from the overlap quark propagator

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Bi, Yujiang; Cai, Hao; Chen, Ying; Gong, Ming; Liu, Zhaofeng

    2017-05-01

    From the overlap lattice quark propagator calculated in the Landau gauge, we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data. The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with N f = 2+1 flavors. Three ensembles with different light sea quark masses are used at one lattice spacing 1/a = 1.75(4) GeV. We obtain in the SU(2) chiral limit. Supported by National Natural Science Foundation of China (11575197, 11575196, 11335001, 11405178), joint funds of NSFC (U1632104, U1232109), YC and ZL acknowledge the support of NSFC and DFG (CRC110)

  5. Conformal versus confining scenario in SU(2) with adjoint fermions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Del Debbio, L.; Pica, C.; Lucini, B.

    2009-10-01

    The masses of the lowest-lying states in the meson and in the gluonic sector of an SU(2) gauge theory with two Dirac flavors in the adjoint representation are measured on the lattice at a fixed value of the lattice coupling {beta}=4/g{sub 0}{sup 2}=2.25 for values of the bare fermion mass m{sub 0} that span a range between the quenched regime and the massless limit, and for various lattice volumes. Even for light constituent fermions the lightest glueballs are found to be lighter than the lightest mesons. Moreover, the string tension between two static fundamental sources strongly depends on the massmore » of the dynamical fermions and becomes of the order of the inverse squared lattice linear size before the chiral limit is reached. The implications of these findings for the phase of the theory in the massless limit are discussed and a strategy for discriminating between the (near-)conformal and the confining scenario is outlined.« less

  6. Chiral Magnetic Effect and Anomalous Transport from Real-Time Lattice Simulations

    DOE PAGES

    Müller, Niklas; Schlichting, Sören; Sharma, Sayantan

    2016-09-30

    Here, we present a first-principles study of anomaly induced transport phenomena by performing real-time lattice simulations with dynamical fermions coupled simultaneously to non-Abelian S U ( N c ) and Abelian U ( 1 ) gauge fields. By investigating the behavior of vector and axial currents during a sphaleron transition in the presence of an external magnetic field, we demonstrate how the interplay of the chiral magnetic and chiral separation effect leads to the formation of a propagating wave. Furthermore, we analyze the dependence of the magnitude of the induced vector current and the propagation of the wave on themore » amount of explicit chiral symmetry breaking due to finite quark masses.« less

  7. Möbius domain-wall fermions on gradient-flowed dynamical HISQ ensembles

    NASA Astrophysics Data System (ADS)

    Berkowitz, Evan; Bouchard, Chris; Chang, Chia Cheng; Clark, M. A.; Joó, Bálint; Kurth, Thorsten; Monahan, Christopher; Nicholson, Amy; Orginos, Kostas; Rinaldi, Enrico; Vranas, Pavlos; Walker-Loud, André

    2017-09-01

    We report on salient features of a mixed lattice QCD action using valence Möbius domain-wall fermions solved on the dynamical Nf=2 +1 +1 highly improved staggered quark sea-quark ensembles generated by the MILC Collaboration. The approximate chiral symmetry properties of the valence fermions are shown to be significantly improved by utilizing the gradient-flow scheme to first smear the highly improved staggered quark configurations. The greater numerical cost of the Möbius domain-wall inversions is mitigated by the highly efficient QUDA library optimized for NVIDIA GPU accelerated compute nodes. We have created an interface to this optimized QUDA solver in Chroma. We provide tuned parameters of the action and performance of QUDA using ensembles with the lattice spacings a ≃{0.15 ,0.12 ,0.09 } fm and pion masses mπ≃{310 ,220 ,130 } MeV . We have additionally generated two new ensembles with a ˜0.12 fm and mπ˜{400 ,350 } MeV . With a fixed flow time of tg f=1 in lattice units, the residual chiral symmetry breaking of the valence fermions is kept below 10% of the light quark mass on all ensembles, mres≲0.1 ×ml , with moderate values of the fifth dimension L5 and a domain-wall height M5≤1.3 . As a benchmark calculation, we perform a continuum, infinite volume, physical pion and kaon mass extrapolation of FK±/Fπ± and demonstrate our results are independent of flow time and consistent with the FLAG determination of this quantity at the level of less than one standard deviation.

  8. Staggered heavy baryon chiral perturbation theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bailey, Jon A.

    2008-03-01

    Although taste violations significantly affect the results of staggered calculations of pseudoscalar and heavy-light mesonic quantities, those entering staggered calculations of baryonic quantities have not been quantified. Here I develop staggered chiral perturbation theory in the light-quark baryon sector by mapping the Symanzik action into heavy baryon chiral perturbation theory. For 2+1 dynamical quark flavors, the masses of flavor-symmetric nucleons are calculated to third order in partially quenched and fully dynamical staggered chiral perturbation theory. To this order the expansion includes the leading chiral logarithms, which come from loops with virtual decuplet-like states, as well as terms of O(m{sub {pi}}{supmore » 3}), which come from loops with virtual octet-like states. Taste violations enter through the meson propagators in loops and tree-level terms of O(a{sup 2}). The pattern of taste symmetry breaking and the resulting degeneracies and mixings are discussed in detail. The resulting chiral forms are appropriate to lattice results obtained with operators already in use and could be used to study the restoration of taste symmetry in the continuum limit. I assume that the fourth root of the fermion determinant can be incorporated in staggered chiral perturbation theory using the replica method.« less

  9. Characteristics of chiral anomaly in view of various applications

    NASA Astrophysics Data System (ADS)

    Fujikawa, Kazuo

    2018-01-01

    In view of the recent applications of chiral anomaly to various fields beyond particle physics, we discuss some basic aspects of chiral anomaly which may help deepen our understanding of chiral anomaly in particle physics also. It is first shown that Berry's phase (and its generalization) for the Weyl model H =vFσ →.p →(t ) assumes a monopole form at the exact adiabatic limit but deviates from it off the adiabatic limit and vanishes in the high frequency limit of the Fourier transform of p →(t ) for bounded |p →(t )|. An effective action, which is consistent with the nonadiabatic limit of Berry's phase, combined with the Bjorken-Johnson-Low prescription, gives normal equal-time space-time commutators and no chiral anomaly. In contrast, an effective action with a monopole at the origin of the momentum space, which describes Berry's phase in the precise adiabatic limit but fails off the adiabatic limit, gives anomalous space-time commutators and a covariant anomaly to the gauge current. We regard this anomaly as an artifact of the postulated monopole and not a consequence of Berry's phase. As for the recent application of the chiral anomaly to the description of effective Weyl fermions in condensed matter and nuclear physics, which is closely related to the formulation of lattice chiral fermions, we point out that the chiral anomaly for each species doubler separately vanishes for a finite lattice spacing, contrary to the common assumption. Instead, a general form of pair creation associated with the spectral flow for the Dirac sea with finite depth takes place. This view is supported by the Ginsparg-Wilson fermion, which defines a single Weyl fermion without doublers on the lattice and gives a well-defined index (anomaly) even for a finite lattice spacing. A different use of anomaly in analogy to the partially conserved axial-vector current is also mentioned and could lead to an effect without fermion number nonconservation.

  10. S parameter and pseudo Nambu-Goldstone boson mass from lattice QCD.

    PubMed

    Shintani, E; Aoki, S; Fukaya, H; Hashimoto, S; Kaneko, T; Matsufuru, H; Onogi, T; Yamada, N

    2008-12-12

    We present a lattice calculation of L10, one of the low-energy constants in chiral perturbation theory, and the charged-neutral pion squared-mass splitting, using dynamical overlap fermion. The exact chiral symmetry of the overlap fermion allows us to reliably extract these quantities from the difference of the vacuum polarization functions for vector and axial-vector currents. In the context of the technicolor models, these two quantities are read as the S parameter and the pseudo Nambu-Goldstone boson mass, respectively, and play an important role in discriminating the models from others. This calculation can serve as a feasibility study of the lattice techniques for more general technicolor gauge theories.

  11. Aspects of Chiral Symmetry Breaking in Lattice QCD

    NASA Astrophysics Data System (ADS)

    Horkel, Derek P.

    In this thesis we describe two studies concerting lattice quantum chromodynamics (LQCD): first, an analysis of the phase structure of Wilson and twisted-mass fermions with isospin breaking effects, second a computational study measuring non-perturbative Greens functions. We open with a brief overview of the formalism of QCD and LQCD, focusing on the aspects necessary for understanding how a lattice computation is performed and how discretization effects can be understood. Our work in Wilson and twisted-mass fermions investigates an increasingly relevant regime where lattice simulations are performed with quarks at or near their physical masses and both the mass difference of the up and down quarks and their differing electric charges are included. Our computation of a non-perturbative Greens functions on the lattice serves as a first attempt to validate recent work by Dine et. al. [24] in which they calculate Greens functions which vanish in perturbation theory, yet have a contribution from the one instanton background. In chapter 2, we determine the phase diagram and pion spectrum for Wilson and twisted-mass fermions in the presence of non-degeneracy between the up and down quark and discretization errors, using Wilson and twisted-mass chiral perturbation theory. We find that the CP-violating phase of the continuum theory (which occurs for sufficiently large non-degeneracy) is continuously connected to the Aoki phase of the lattice theory with degenerate quarks. We show that discretization effects can, in some cases, push simulations with physical masses closer to either the CP-violating phase or another phase not present in the continuum, so that at sufficiently large lattice spacings physical-point simulations could lie in one of these phases. In chapter 3, we extend the work in chapter 2 to include the effects of electromagnetism, so that it is applicable to recent simulations incorporating all sources of isospin breaking. For Wilson fermions, we find that the

  12. Aspect of Fermion Mass Hierarchy within Flavor Democracy for Yukawa Couplings

    NASA Astrophysics Data System (ADS)

    Higuchi, Katsuichi; Yamamoto, Katsuji

    We discuss the fermion mass hierarchy by including vector-like fermions which are accommodated in E6 GUTs within flavor democracy for Yukawa couplings. In this framework, all Yukawa couplings for the standard Higgs doublet have the same strength, and all Yukawa couplings for the singlet Higgs have the same strength (New ansatz). In addition, singlet Higgs and right-handed neutrinos exist. Under this condition, the mass hierarchy mt ≫ mb ˜ mτ as well as mt ≫ mc, mu can be naturally explained.

  13. Rooting issue for a lattice fermion formulation similar to staggered fermions but without taste mixing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Adams, David H.

    2008-05-15

    To investigate the viability of the 4th root trick for the staggered fermion determinant in a simpler setting, we consider a 2-taste (flavor) lattice fermion formulation with no taste mixing but with exact taste-nonsinglet chiral symmetries analogous to the taste-nonsinglet U(1){sub A} symmetry of staggered fermions. Creutz's objections to the rooting trick apply just as much in this setting. To counter them we show that the formulation has robust would-be zero modes in topologically nontrivial gauge backgrounds, and that these manifest themselves in a viable way in the rooted fermion determinant and also in the disconnected piece of the pseudoscalarmore » meson propagator as required to solve the U(1) problem. Also, our rooted theory is heuristically seen to be in the right universality class for QCD if the same is true for an unrooted mixed fermion action theory.« less

  14. Phenomenology of strongly coupled chiral gauge theories

    DOE PAGES

    Bai, Yang; Berger, Joshua; Osborne, James; ...

    2016-11-25

    A sector with QCD-like strong dynamics is common in models of non-standard physics. Such a model could be accessible in LHC searches if both confinement and big-quarks charged under the confining group are at the TeV scale. Big-quark masses at this scale can be explained if the new fermions are chiral under a new U(1)' gauge symmetry such that their bare masses are related to the U(1)'-breaking and new confinement scales. Here we present a study of a minimal GUT-motivated and gauge anomaly-free model with implications for the LHC Run 2 searches. We find that the first signatures of suchmore » models could appear as two gauge boson resonances. The chiral nature of the model could be confirmed by observation of a Z'γ resonance, where the Z' naturally has a large leptonic branching ratio because of its kinetic mixing with the hypercharge gauge boson.« less

  15. Polar Kerr effect studies of time reversal symmetry breaking states in heavy fermion superconductors

    DOE PAGES

    Schemm, E. R.; Levenson-Falk, E. M.; Kapitulnik, A.

    2016-11-30

    The connection between chiral superconductivity and topological order has emerged as an active direction in research as more instances of both have been identified in condensed matter systems. Moreover, with the notable exception of 3He-B, all of the known or suspected chiral – that is to say time-reversal symmetry-breaking (TRSB) – superfluids arise in heavy fermion superconductors, although the vast majority of heavy fermion superconductors preserve time-reversal symmetry. We review recent experimental efforts to identify TRSB states in heavy fermion systems via measurement of polar Kerr effect, which is a direct consequence of TRSB.

  16. Interrelating Fermion Masses, CP Violation and Baryogenesis via Grand Unification

    NASA Astrophysics Data System (ADS)

    Pati, Jogesh C.

    2005-08-01

    An attempt is made to interrelate (i) fermion masses, (ii) neutrino oscillations, (iii) CP and flavor violations, and (iv) baryogenesis via leptogenesis, within supersymmetric grand unification, based on an effective symmetry which is either G(224) = SU(2)L × SU(2)R × SU(4)c or SO(10). Reviewing the framework proposed in this context by Babu, Pati and Wilczek (BPW), which successfully describes fermion masses and neutrino oscillations, a recent work by Babu, Rastogi and me is presented. It is shown that the BPW framework can be extended rather simply to include CP violation that is intimately linked to fermion masses and neutrino oscillations. Including SM and SUSY contributions, it is found that the extension can correctly account for the observed flavor and/or CP violations in ΔmK, ΔmBd, S(Bd → J/ψKS) as well as ɛK, while retaining the successes of the BPW framework as regards fermion masses and neutrino oscillations. While SUSY contribution is small (≲ few%) for the first three quantities, that to ɛK is sizable (~ 20-25%) and negative (as desired) compared to that of the SM. The model predicts S(Bd → ϕKS) to be in the range +(0.65-0.73), close to the SM prediction. The model yields Re(ɛ'/ɛ)SUSY ≈ +(4 - 14) × 10-4 the relevance of this contribution can be assessed only when the associated matrix elements are known reliably. The model also predicts that the electric dipole moments of the neutron and the electron, as well as the rare processes μ → eγ and τ → μγ, should be discovered with improvements in the current limits by factors of 10 to 100. Last but not the least, the model naturally leads to baryogenesis via leptogenesis in good accord with observation.

  17. On a chiral analog of the Einstein-de Haas effect

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zakharov, V. I., E-mail: vzakharov@itep.ru

    The Einstein-de Haas effect reveals a transfer of angular momentum from microscopic constituents (electrons) to a macroscopic body, but in the case of massless fermions, one could expect the transfer of the chirality of constituents to macroscopic helical motion. For such a picture to be consistent, the macroscopic helicity is to be conserved classically, to echo the conservation of the angular momentum of a rotating body. The helicity conservation would in turn impose constraints on hydrodynamics of chiral liquids (whose constituents are massless fermions). Essentially, the chiral liquids are dissipation-free, on the classical level. Reservations and alternatives to this scenariomore » are discussed.« less

  18. Relating quark confinement and chiral symmetry breaking in QCD

    NASA Astrophysics Data System (ADS)

    Suganuma, Hideo; Doi, Takahiro M.; Redlich, Krzysztof; Sasaki, Chihiro

    2017-12-01

    We study the relation between quark confinement and chiral symmetry breaking in QCD. Using lattice QCD formalism, we analytically express the various ‘confinement indicators’, such as the Polyakov loop, its fluctuations, the Wilson loop, the inter-quark potential and the string tension, in terms of the Dirac eigenmodes. In the Dirac spectral representation, there appears a power of the Dirac eigenvalue {λ }n such as {λ }n{Nt-1}, which behaves as a reduction factor for small {λ }n. Consequently, since this reduction factor cannot be cancelled, the low-lying Dirac eigenmodes give negligibly small contribution to the confinement quantities, while they are essential for chiral symmetry breaking. These relations indicate that there is no direct one-to-one correspondence between confinement and chiral symmetry breaking in QCD. In other words, there is some independence of quark confinement from chiral symmetry breaking, which can generally lead to different transition temperatures/densities for deconfinement and chiral restoration. We also investigate the Polyakov loop in terms of the eigenmodes of the Wilson, the clover and the domain-wall fermion kernels, and find similar results. The independence of quark confinement from chiral symmetry breaking seems to be natural, because confinement is realized independently of quark masses and heavy quarks are also confined even without the chiral symmetry.

  19. Fermion masses and mixing in general warped extra dimensional models

    NASA Astrophysics Data System (ADS)

    Frank, Mariana; Hamzaoui, Cherif; Pourtolami, Nima; Toharia, Manuel

    2015-06-01

    We analyze fermion masses and mixing in a general warped extra dimensional model, where all the Standard Model (SM) fields, including the Higgs, are allowed to propagate in the bulk. In this context, a slightly broken flavor symmetry imposed universally on all fermion fields, without distinction, can generate the full flavor structure of the SM, including quarks, charged leptons and neutrinos. For quarks and charged leptons, the exponential sensitivity of their wave functions to small flavor breaking effects yield hierarchical masses and mixing as it is usual in warped models with fermions in the bulk. In the neutrino sector, the exponential wave-function factors can be flavor blind and thus insensitive to the small flavor symmetry breaking effects, directly linking their masses and mixing angles to the flavor symmetric structure of the five-dimensional neutrino Yukawa couplings. The Higgs must be localized in the bulk and the model is more successful in generalized warped scenarios where the metric background solution is different than five-dimensional anti-de Sitter (AdS5 ). We study these features in two simple frameworks, flavor complimentarity and flavor democracy, which provide specific predictions and correlations between quarks and leptons, testable as more precise data in the neutrino sector becomes available.

  20. Chiral magnetic effect in condensed matter systems

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Kharzeev, Dmitri E.

    2016-12-01

    The chiral magnetic effect (CME) is the generation of electrical current induced by chirality imbalance in the presence of magnetic field. It is a macroscopic manifestation of the quantum chiral anomaly [S. L. Adler. Axial-vector vertex in spinor electrodynamics. Physical Review, 177, 2426 (1969), J. S. Bell and R. Jackiw. A PCAC puzzle: π 0 γγin the σ-model. Il Nuovo Cimento A, 60, 47-61 (1969)] in systems possessing charged chiral fermions. In quark-gluon plasma containing nearly massless quarks, the chirality imbalance is sourced by the topological transitions. In condensed matter systems, the chiral quasiparticles emerge in gapless semiconductors with two energy bands having pointlike degeneracies opening the path to the study of chiral anomaly [H. B. Nielsen and M. Ninomiya. The Adler-Bell-Jackiw anomaly and Weyl fermions in a crystal. Physics Letters B, 130, 389-396 (1983)]. Recently, these novel materials - so-called Dirac and Weyl semimetals have been discovered experimentally, are suitable for the investigation of the CME in condensed matter experiments. Here we report on the first experimental observation of the CME in a 3D Dirac semimetal ZrTe5 [Q. Li, D. E. Kharzeev, C. Zhang, Y. Huang, I. Pletikosić, A. V. Fedorov, R. D. Zhong, J. A. Schneeloch, G. D. Gu, and T. Valla. Chiral magnetic effect in ZrTe5. Nature Physics (2016) doi:10.1038/nphys3648].

  1. Spectroscopy of SU(4) composite Higgs theory with two distinct fermion representations

    NASA Astrophysics Data System (ADS)

    Ayyar, Venkitesh; DeGrand, Thomas; Golterman, Maarten; Hackett, Daniel C.; Jay, William I.; Neil, Ethan T.; Shamir, Yigal; Svetitsky, Benjamin

    2018-04-01

    We have simulated the SU(4) lattice gauge theory coupled to dynamical fermions in the fundamental and two-index antisymmetric (sextet) representations simultaneously. Such theories arise naturally in the context of composite Higgs models that include a partially composite top quark. We describe the low-lying meson spectrum of the theory and fit the pseudoscalar masses and decay constants to chiral perturbation theory. We infer as well the mass and decay constant of the Goldstone boson corresponding to the nonanomalous U(1) symmetry of the model. Our results are broadly consistent with large-Nc scaling and vector-meson dominance.

  2. Leading chiral logarithms for the nucleon mass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vladimirov, Alexey A.; Bijnens, Johan

    2016-01-22

    We give a short introduction to the calculation of the leading chiral logarithms, and present the results of the recent evaluation of the LLog series for the nucleon mass within the heavy baryon theory. The presented results are the first example of LLog calculation in the nucleon ChPT. We also discuss some regularities observed in the leading logarithmical series for nucleon mass.

  3. Multigrid accelerated simulations for Twisted Mass fermions

    NASA Astrophysics Data System (ADS)

    Bacchio, Simone; Alexandrou, Constantia; Finkerath, Jacob

    2018-03-01

    Simulations at physical quark masses are affected by the critical slowing down of the solvers. Multigrid preconditioning has proved to deal effectively with this problem. Multigrid accelerated simulations at the physical value of the pion mass are being performed to generate Nf = 2 and Nf = 2 + 1 + 1 gauge ensembles using twisted mass fermions. The adaptive aggregation-based domain decomposition multigrid solver, referred to as DD-αAMG method, is employed for these simulations. Our simulation strategy consists of an hybrid approach of different solvers, involving the Conjugate Gradient (CG), multi-mass-shift CG and DD-αAMG solvers. We present an analysis of the multigrid performance during the simulations discussing the stability of the method. This significant speeds up the Hybrid Monte Carlo simulation by more than a factor 4 at physical pion mass compared to the usage of the CG solver.

  4. Inertial Mass from Spin Nonlinearity

    NASA Astrophysics Data System (ADS)

    Cohen, Marcus

    The inertial mass of a Fermion shows up as chiral cross-coupling in its Dirac system. No scalar term can invariantly couple left and right chirality fields; the Dirac matrices must be spin tensors of mixed chirality. We show how such tensor couplings could arise from nonlinear mixing of four spinor fields, two representing the local electron fields and two inertial spinor fields sourced in the distant masses. We thus give a model that implements Mach's principle. Following Mendel Sachs,1 we let the inertial spinors factor the moving spacetime tetrads qα(x) and bar {q}α (x) that appear in the Dirac operator. The inertial spinors do more than set the spacetime "stage;" they are players in the chiral dynamics. Specifically, we show how the massive Dirac system arises as the envelope modulation equations coupling left and right chirality electron fields on a Friedmann universe via nonlinear "spin gratings" with the inertial spinor fields. These gratings implement Penrose's "mass-scatterings," which keep the null zig-zags of the bispinor wave function confined to a timelike world tube. Local perturbations to the inertial spinor fields appear in the Dirac system as Abelian and non-Abelian vector potentials.

  5. Compatible orders and fermion-induced emergent symmetry in Dirac systems

    NASA Astrophysics Data System (ADS)

    Janssen, Lukas; Herbut, Igor F.; Scherer, Michael M.

    2018-01-01

    We study the quantum multicritical point in a (2+1)-dimensional Dirac system between the semimetallic phase and two ordered phases that are characterized by anticommuting mass terms with O (N1) and O (N2) symmetries, respectively. Using ɛ expansion around the upper critical space-time dimension of four, we demonstrate the existence of a stable renormalization-group fixed point, enabling a direct and continuous transition between the two ordered phases directly at the multicritical point. This point is found to be characterized by an emergent O (N1+N2) symmetry for arbitrary values of N1 and N2 and fermion flavor numbers Nf as long as the corresponding representation of the Clifford algebra exists. Small O (N ) -breaking perturbations near the chiral O (N ) fixed point are therefore irrelevant. This result can be traced back to the presence of gapless Dirac degrees of freedom at criticality, and it is in clear contrast to the purely bosonic O (N ) fixed point, which is stable only when N <3 . As a by-product, we obtain predictions for the critical behavior of the chiral O (N ) universality classes for arbitrary N and fermion flavor number Nf. Implications for critical Weyl and Dirac systems in 3+1 dimensions are also briefly discussed.

  6. Anomaly constraints on deconfinement and chiral phase transition

    NASA Astrophysics Data System (ADS)

    Shimizu, Hiroyuki; Yonekura, Kazuya

    2018-05-01

    We study the constraints on thermal phase transitions of SU (Nc) gauge theories by using the 't Hooft anomaly involving the center symmetry and chiral symmetry. We consider two cases of massless fermions: (i) adjoint fermions and (ii) Nf flavors of fundamental fermions with a nontrivial greatest common divisor, gcd (Nc,Nf)≠1 . For the first case (i), we show that the chiral symmetry restoration in terms of the standard Landau-Ginzburg effective action is impossible at a temperature lower than that of deconfinement. For the second case (ii), we introduce a modified version of the center symmetry, which we call center-flavor symmetry, and draw similar conclusions under a certain definition of confinement. Moreover, at zero temperature, our results give a partial explanation of the appearance of dual magnetic gauge groups in (supersymmetric) QCD when gcd (Nc,Nf)≠1 .

  7. Chiral magnetic effect in condensed matter systems

    DOE PAGES

    Li, Qiang; Kharzeev, Dmitri E.

    2016-12-01

    The chiral magnetic effect is the generation of electrical current induced by chirality imbalance in the presence of magnetic field. It is a macroscopic manifestation of the quantum anomaly in relativistic field theory of chiral fermions. In the quark-gluon plasma, the axial anomaly induces topological charge changing transition that results in the generation of electrical current along the magnetic field. In condensed matter systems, the chiral magnetic effect was first predicted in the gapless semiconductors with tow energy bands having pointlike degeneracies. In addition, thirty years later after this prediction, the chiral magnetic effect was finally observed in the 3Dmore » Dirac/Weyl semimetals.« less

  8. Chiral magnetic effect without chirality source in asymmetric Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Kharzeev, Dmitri E.; Kikuchi, Yuta; Meyer, René

    2018-05-01

    We describe a new type of the chiral magnetic effect (CME) that should occur in Weyl semimetals (WSMs) with an asymmetry in the dispersion relations of the left- and right-handed (LH and RH) chiral Weyl fermions. In such materials, time-dependent pumping of electrons from a non-chiral external source can generate a non-vanishing chiral chemical potential. This is due to the different capacities of the LH and RH chiral Weyl cones arising from the difference in the density of states in the LH and RH cones. The chiral chemical potential then generates, via the chiral anomaly, a current along the direction of an applied magnetic field even in the absence of an external electric field. The source of chirality imbalance in this new setup is thus due to the band structure of the system and the presence of (non-chiral) electron source, and not due to the parallel electric and magnetic fields. We illustrate the effect by an argument based on the effective field theory, and by the chiral kinetic theory calculation for a rotationally invariant WSM with different Fermi velocities in the left and right chiral Weyl cones; we also consider the case of a WSM with Weyl nodes at different energies. We argue that this effect is generically present in WSMs with different dispersion relations for LH and RH chiral Weyl cones, such as SrSi2 recently predicted as a WSM with broken inversion and mirror symmetries, as long as the chiral relaxation time is much longer than the transport scattering time.

  9. On consistency of hydrodynamic approximation for chiral media

    NASA Astrophysics Data System (ADS)

    Avdoshkin, A.; Kirilin, V. P.; Sadofyev, A. V.; Zakharov, V. I.

    2016-04-01

    We consider chiral liquids, that is liquids consisting of massless fermions and right-left asymmetric. In such media, one expects existence of electromagnetic current flowing along an external magnetic field, associated with the chiral anomaly. The current is predicted to be dissipation-free. We consider dynamics of chiral liquids, concentrating on the issues of possible instabilities and infrared sensitivity. Instabilities arise, generally speaking, already in the limit of vanishing electromagnetic constant, αel → 0. In particular, liquids with non-vanishing chiral chemical potential might decay into right-left asymmetric states containing vortices.

  10. General structure of fermion two-point function and its spectral representation in a hot magnetized medium

    NASA Astrophysics Data System (ADS)

    Das, Aritra; Bandyopadhyay, Aritra; Roy, Pradip K.; Mustafa, Munshi G.

    2018-02-01

    We have systematically constructed the general structure of the fermion self-energy and the effective quark propagator in the presence of a nontrivial background such as a hot magnetized medium. This is applicable to both QED and QCD. The hard thermal loop approximation has been used for the heat bath. We have also examined transformation properties of the effective fermion propagator under some of the discrete symmetries of the system. Using the effective fermion propagator we have analyzed the fermion dispersion spectra in a hot magnetized medium along with the spinor for each fermion mode obtained by solving the modified Dirac equation. The fermion spectra is found to reflect the discrete symmetries of the two-point functions. We note that for a chirally symmetric theory the degenerate left- and right-handed chiral modes in vacuum or in a heat bath get separated and become asymmetric in the presence of a magnetic field without disturbing the chiral invariance. The obtained general structure of the two-point functions is verified by computing the three-point function, which agrees with the existing results in one-loop order. Finally, we have computed explicitly the spectral representation of the two-point functions which would be very important to study the spectral properties of the hot magnetized medium corresponding to QED and QCD with background magnetic field.

  11. Chiral Tricritical Point: A New Universality Class in Dirac Systems

    NASA Astrophysics Data System (ADS)

    Yin, Shuai; Jian, Shao-Kai; Yao, Hong

    2018-05-01

    Tricriticality, as a sister of criticality, is a fundamental and absorbing issue in condensed-matter physics. It has been verified that the bosonic Wilson-Fisher universality class can be changed by gapless fermionic modes at criticality. However, the counterpart phenomena at tricriticality have rarely been explored. In this Letter, we study a model in which a tricritical Ising model is coupled to massless Dirac fermions. We find that the massless Dirac fermions result in the emergence of a new tricritical point, which we refer to as the chiral tricritical point (CTP), at the phase boundary between the Dirac semimetal and the charge-density wave insulator. From functional renormalization group analysis of the effective action, we obtain the critical behaviors of the CTP, which are qualitatively distinct from both the tricritical Ising universality and the chiral Ising universality. We further extend the calculations of the chiral tricritical behaviors of Ising spins to the case of Heisenberg spins. The experimental relevance of the CTP in two-dimensional Dirac semimetals is also discussed.

  12. Weak antilocalization of composite fermions in graphene

    NASA Astrophysics Data System (ADS)

    Laitinen, Antti; Kumar, Manohar; Hakonen, Pertti J.

    2018-02-01

    We demonstrate experimentally that composite fermions in monolayer graphene display weak antilocalization. Our experiments deal with fractional quantum Hall (FQH) states in high-mobility, suspended graphene Corbino disks in the vicinity of ν =1 /2 . We find a strong temperature dependence of conductivity σ away from half filling, which is consistent with the expected electron-electron interaction-induced gaps in the FQH state. At half filling, however, the temperature dependence of conductivity σ (T ) becomes quite weak, as anticipated for a Fermi sea of composite fermions, and we find a logarithmic dependence of σ on T . The sign of this quantum correction coincides with the weak antilocalization of graphene composite fermions, indigenous to chiral Dirac particles.

  13. Chiral magnetic effect of light

    NASA Astrophysics Data System (ADS)

    Hayata, Tomoya

    2018-05-01

    We study a photonic analog of the chiral magnetic (vortical) effect. We discuss that the vector component of magnetoelectric tensors plays a role of "vector potential," and its rotation is understood as "magnetic field" of a light. Using the geometrical optics approximation, we show that "magnetic fields" cause an anomalous shift of a wave packet of a light through an interplay with the Berry curvature of photons. The mechanism is the same as that of the chiral magnetic (vortical) effect of a chiral fermion, so that we term the anomalous shift "chiral magnetic effect of a light." We further study the chiral magnetic effect of a light beyond geometric optics by directly solving the transmission problem of a wave packet at a surface of a magnetoelectric material. We show that the experimental signal of the chiral magnetic effect of a light is the nonvanishing of transverse displacements for the beam normally incident to a magnetoelectric material.

  14. Chiral anomaly and anomalous finite-size conductivity in graphene

    NASA Astrophysics Data System (ADS)

    Shen, Shun-Qing; Li, Chang-An; Niu, Qian

    2017-09-01

    Graphene is a monolayer of carbon atoms packed into a hexagon lattice to host two spin degenerate pairs of massless two-dimensional Dirac fermions with different chirality. It is known that the existence of non-zero electric polarization in reduced momentum space which is associated with a hidden chiral symmetry will lead to the zero-energy flat band of a zigzag nanoribbon and some anomalous transport properties. Here it is proposed that the Adler-Bell-Jackiw chiral anomaly or non-conservation of chiral charges of Dirac fermions at different valleys can be realized in a confined ribbon of finite width, even in the absence of a magnetic field. In the laterally diffusive regime, the finite-size correction to conductivity is always positive and is inversely proportional to the square of the lateral dimension W, which is different from the finite-size correction inversely proportional to W from the boundary modes. This anomalous finite-size conductivity reveals the signature of the chiral anomaly in graphene, and it is measurable experimentally. This finding provides an alternative platform to explore the purely quantum mechanical effect in graphene.

  15. The resonant state at filling factor ν = 1/2 in chiral fermionic ladders

    NASA Astrophysics Data System (ADS)

    Haller, Andreas; Rizzi, Matteo; Burrello, Michele

    2018-05-01

    Helical liquids have been experimentally realized in both nanowires and ultracold atomic chains as the result of strong spin–orbit interactions. In both cases the inner degrees of freedom can be considered as an additional space dimension, providing an interpretation of these systems as chiral synthetic ladders, with artificial magnetic fluxes determined by the spin–orbit terms. In this work, we characterize the helical state which appears at filling ν = 1/2: this state is generated by a gap arising in the spin sector of the corresponding Luttinger liquid and it can be interpreted as the one-dimensional (1D) limit of a fractional quantum Hall state of bosonic pairs of fermions. We study its main features, focusing on entanglement properties and correlation functions. The techniques developed here provide a key example for the study of similar quasi-1D systems beyond the semiclassical approximation commonly adopted in the description of the Laughlin-like states.

  16. A new mechanism of mass protection for fermions

    NASA Astrophysics Data System (ADS)

    Alonso, J. L.; Boucaud, Ph.; Carmona, J. M.; Cortés, J. L.; Polonyi, J.; van der Sijs, A. J.

    We present a way of protecting a Dirac fermion interacting with a scalar (Higgs) field from getting a mass from the vacuum. It is obtained through an implementation of translational symmetry when the theory is formulated with a momentum cutoff, which forbids the usual Yukawa term. We consider that this mechanism can help to understand the smallness of neutrino masses without a tuning of the Yukawa coupling. The prohibition of the Yukawa term for the neutrino forbids at the same time a gauge coupling between the right-handed electron and neutrino. We prove that this mechanism can be implemented on the lattice.

  17. Chiral anomaly and longitudinal magnetotransport in type-II Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Sharma, Girish; Goswami, Pallab; Tewari, Sumanta

    2017-07-01

    In the presence of parallel electric and magnetic fields, the violation of a separate number conservation laws for the three-dimensional left- and right-handed Weyl fermions is known as the chiral anomaly. The recent discovery of Weyl and Dirac semimetals has paved the way for experimentally testing the effects of chiral anomaly via magnetotransport measurements, since chiral anomaly can lead to negative longitudinal magnetoresistance (LMR) while the transverse magnetoresistance remains positive. More recently, a type-II Weyl semimetal (WSM) phase has been proposed, where the nodal points possess a finite density of states due to the touching between electron and hole pockets. It has been suggested that the main difference between the two types of WSMs (type I and type II) is that in the latter, chiral-anomaly-induced negative LMR (positive longitudinal magnetoconductance) is strongly anisotropic, vanishing when the applied magnetic field is perpendicular to the direction of tilt of Weyl fermion cones in a type-II WSM. We analyze chiral anomaly in a type-II WSM in a quasiclassical Boltzmann framework, and find that the chiral-anomaly-induced positive longitudinal magnetoconductivity is present along any arbitrary direction. Thus, our results are pertinent for uncovering transport signatures of type-II WSMs in different candidate materials.

  18. Minimally doubled fermions at one loop

    NASA Astrophysics Data System (ADS)

    Capitani, Stefano; Weber, Johannes; Wittig, Hartmut

    2009-10-01

    Minimally doubled fermions have been proposed as a cost-effective realization of chiral symmetry at non-zero lattice spacing. Using lattice perturbation theory at one loop, we study their renormalization properties. Specifically, we investigate the consequences of the breaking of hyper-cubic symmetry, which is a typical feature of this class of fermionic discretizations. Our results for the quark self-energy indicate that the four-momentum undergoes a renormalization which is linearly divergent. We also compute renormalization factors for quark bilinears, construct the conserved vector and axial-vector currents and verify that at one loop the renormalization factors of the latter are equal to one.

  19. The origin of mass

    NASA Astrophysics Data System (ADS)

    Froggatt*, C. D.

    2003-01-01

    The quark-lepton mass problem and the ideas of mass protection are reviewed. The hierarchy problem and suggestions for its resolution, including Little Higgs models, are discussed. The Multiple Point Principle (MPP) is introduced and used within the Standard Model (SM) to predict the top quark and Higgs particle masses. Mass matrix ansätze are considered; in particular we discuss the lightest family mass generation model, in which all the quark mixing angles are successfully expressed in terms of simple expressions involving quark mass ratios. It is argued that an underlying chiral flavour symmetry is responsible for the hierarchical texture of the fermion mass matrices. The phenomenology of neutrino mass matrices is briefly discussed.

  20. Drag suppression in anomalous chiral media

    DOE PAGES

    Sadofyev, Andrey V.; Yin, Yi

    2016-06-01

    We study a heavy impurity moving longitudinal with the direction of an external magnetic field in an anomalous chiral medium. Such system would carry a non-dissipative current of chiral magnetic effect associated with the anomaly. We show, by generalizing Landau's criterion for super fluidity, that the "anomalous component" which gives rise to the anomalous transport will not contribute to the drag experienced by an impurity. We argue on a very general basis that those systems with a strong magnetic field would exhibit an interesting transport phenomenon$-$the motion of the heavy impurity is frictionless, in analogy to the case of amore » super fluid. Finally, we demonstrate and confirm our general results with two complementary examples: weakly coupled chiral fermion gases and strongly interacting chiral liquids.« less

  1. Instanton-dyon ensembles reproduce deconfinement and chiral restoration phase transitions

    NASA Astrophysics Data System (ADS)

    Shuryak, Edward

    2018-03-01

    Paradigm shift in gauge topology at finite temperatures, from the instantons to their constituents - instanton-dyons - has recently lead to studies of their ensembles and very significant advances. Like instantons, they have fermionic zero modes, and their collectivization at suffciently high density explains the chiral symmetry breaking transition. Unlike instantons, these objects have electric and magnetic charges. Simulations of the instanton-dyon ensembles have demonstrated that their back reaction on the Polyakov line modifies its potential and generates the deconfinement phase transition. For the Nc = 2 gauge theory the transition is second order, for QCD-like theory with Nc = 2 and two light quark flavors Nf = 2 both transitions are weak crossovers at happening at about the same condition. Introduction of quark-flavor-dependent periodicity phases (imaginary chemical potentials) leads to drastic changes in both transitions. In particulaly, in the so called Z(Nc) - QCD model the deconfinement transforms to strong first order transition, while the chiral condensate does not disappear at all. The talk will also cover more detailed studies of correlations between the dyons, effective eta' mass and other screening masses.

  2. Investigation of a driven fermionic system and detecting chiral edge modes in an optical lattice

    NASA Astrophysics Data System (ADS)

    Görg, Frederik; Messer, Michael; Jotzu, Gregor; Sandholzer, Kilian; Desbuquois, Rémi; Goldman, Nathan; Esslinger, Tilman

    2017-04-01

    Periodically driven systems of ultracold fermions in optical lattices allow to implement a large variety of effective Hamiltonians through Floquet engineering. An important question is whether this method can be extended to interacting systems. We investigate driven two-body systems in an array of double wells and measure the double occupancy and the spin-spin correlator in the large frequency limit and when driving resonantly to an energy scale of the underlying static Hamiltonian. We analyze whether the emerging states of the driven system can be adiabatically connected to states in the unshaken lattice. In addition, we measure the amplitude of the micromotion which describes the short time dynamics of the system and compare it directly to theory. In another context we propose a method to create topological interfaces and detect chiral edge modes in a two dimensional optical lattice. We illustrate this through an optical lattice realization of the Haldane model for cold atoms, where an additional spatially-varying lattice potential induces distinct topological phases in separated regions of space.

  3. Out-of-equilibrium chiral magnetic effect from chiral kinetic theory

    NASA Astrophysics Data System (ADS)

    Huang, Anping; Jiang, Yin; Shi, Shuzhe; Liao, Jinfeng; Zhuang, Pengfei

    2018-02-01

    Recently there has been significant interest in the macroscopic manifestation of chiral anomaly in many-body systems of chiral fermions. A notable example is the Chiral Magnetic Effect (CME). Enthusiastic efforts have been made to search for the CME in the quark-gluon plasma created in heavy ion collisions. A crucial challenge is that the extremely strong magnetic field in such collisions may last only for a brief moment and the CME current may have to occur at so early a stage that the quark-gluon matter is still far from thermal equilibrium. This thus requires modeling of the CME in an out-of-equilibrium setting. With the recently developed theoretical tool of chiral kinetic theory, we make a first phenomenological study of the CME-induced charge separation during the pre-thermal stage in heavy ion collisions. The effect is found to be very sensitive to the time dependence of the magnetic field and also influenced by the initial quark momentum spectrum as well as the relaxation time of the system evolution toward thermal equilibrium. Within the present approach, such pre-thermal charge separation is found to be modest.

  4. Nucleon Structure from 2+1 Flavor Domain Wall QCD at Nearly Physical Pion Mass

    NASA Astrophysics Data System (ADS)

    Ohta, Shigemi

    2011-05-01

    The RBC and UKQCD collaborations have been investigating hadron physics in numerical lattice quantum chromodynamics (QCD) with (2+1) flavors of dynamical domain wall fermions (DWF) quarks that preserves continuum-like chiral and flavor symmetries. The strange quark mass is adjusted to physical value via reweighting and degenerate up and down quark masses are set as light as possible. In a recent study of nucleon structure we found a strong dependence on pion mass and lattice spatial extent in isovector axialvector-current form factors. This is likely the first credible evidence for the pion cloud surrounding nucleon. Here we report the status of nucleon structure calculations with a new (2+1)-flavor dynamical DWF ensembles with much lighter pion mass of 180 and 250 MeV and a much larger lattice spatial exent of 4.6 fm. A combination of the Iwasaki and dislocation-suppressing-determinant-ratio (I+DSDR) gauge action and DWF fermion action allows us to generate these ensembles at cutoff of about 1.4 GeV while keeping the residual breaking of chiral symmetry sufficiently small. Nucleon source Gaussian smearing has been optimized. Preliminary nucleon mass estimates are 0.98 and 1.05 GeV.

  5. Worldline construction of a covariant chiral kinetic theory

    DOE PAGES

    Mueller, Niklas; Venugopalan, Raju

    2017-07-27

    Here, we discuss a novel worldline framework for computations of the chiral magnetic effect (CME) in ultrarelativistic heavy-ion collisions. Starting from the fermion determinant in the QCD effective action, we show explicitly how its real part can be expressed as a supersymmetric worldline action of spinning, colored, Grassmannian particles in background fields. Restricting ourselves for simplicity to spinning particles, we demonstrate how their constrained Hamiltonian dynamics arises for both massless and massive particles. In a semiclassical limit, this gives rise to the covariant generalization of the Bargmann-Michel-Telegdi equation; the derivation of the corresponding Wong equations for colored particles is straightforward.more » In a previous paper [N. Mueller and R. Venugopalan, arXiv:1701.03331.], we outlined how Berry’s phase arises in a nonrelativistic adiabatic limit for massive particles. We extend the discussion here to systems with a finite chemical potential. We discuss a path integral formulation of the relative phase in the fermion determinant that places it on the same footing as the real part. We construct the corresponding anomalous worldline axial-vector current and show in detail how the chiral anomaly appears. Our work provides a systematic framework for a relativistic kinetic theory of chiral fermions in the fluctuating topological backgrounds that generate the CME in a deconfined quark-gluon plasma. Finally, we outline some further applications of this framework in many-body systems.« less

  6. Worldline construction of a covariant chiral kinetic theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mueller, Niklas; Venugopalan, Raju

    Here, we discuss a novel worldline framework for computations of the chiral magnetic effect (CME) in ultrarelativistic heavy-ion collisions. Starting from the fermion determinant in the QCD effective action, we show explicitly how its real part can be expressed as a supersymmetric worldline action of spinning, colored, Grassmannian particles in background fields. Restricting ourselves for simplicity to spinning particles, we demonstrate how their constrained Hamiltonian dynamics arises for both massless and massive particles. In a semiclassical limit, this gives rise to the covariant generalization of the Bargmann-Michel-Telegdi equation; the derivation of the corresponding Wong equations for colored particles is straightforward.more » In a previous paper [N. Mueller and R. Venugopalan, arXiv:1701.03331.], we outlined how Berry’s phase arises in a nonrelativistic adiabatic limit for massive particles. We extend the discussion here to systems with a finite chemical potential. We discuss a path integral formulation of the relative phase in the fermion determinant that places it on the same footing as the real part. We construct the corresponding anomalous worldline axial-vector current and show in detail how the chiral anomaly appears. Our work provides a systematic framework for a relativistic kinetic theory of chiral fermions in the fluctuating topological backgrounds that generate the CME in a deconfined quark-gluon plasma. Finally, we outline some further applications of this framework in many-body systems.« less

  7. Chirality and gravitational parity violation.

    PubMed

    Bargueño, Pedro

    2015-06-01

    In this review, parity-violating gravitational potentials are presented as possible sources of both true and false chirality. In particular, whereas phenomenological long-range spin-dependent gravitational potentials contain both truly and falsely chiral terms, it is shown that there are models that extend general relativity including also coupling of fermionic degrees of freedom to gravity in the presence of torsion, which give place to short-range truly chiral interactions similar to that usually considered in molecular physics. Physical mechanisms which give place to gravitational parity violation together with the expected size of the effects and their experimental constraints are discussed. Finally, the possible role of parity-violating gravity in the origin of homochirality and a road map for future research works in quantum chemistry is presented. © 2015 Wiley Periodicals, Inc.

  8. Intersecting branes, Higgs sector, and chirality from N = 4 SYM with soft SUSY breaking

    NASA Astrophysics Data System (ADS)

    Sperling, Marcus; Steinacker, Harold C.

    2018-04-01

    We consider SU( N ) N = 4 super Yang-Mills with cubic and quadratic soft SUSY breaking potential, such that the global SU(4) R is broken to SU(3) or further. As shown recently, this set-up supports a rich set of non-trivial vacua with the geometry of self-intersecting SU(3) branes in 6 extra dimensions. The zero modes on these branes can be interpreted as 3 generations of bosonic and chiral fermionic strings connecting the branes at their intersections. Here, we uncover a large class of exact solutions consisting of branes connected by Higgs condensates, leading to Yukawa couplings between the chiral fermionic zero modes. Under certain decoupling conditions, the backreaction of the Higgs on the branes vanishes exactly. The resulting physics is that of a spontaneously broken chiral gauge theory on branes with fluxes. In particular, we identify combined brane plus Higgs configurations which lead to gauge fields that couple to chiral fermions at low energy. This turns out to be quite close to the Standard Model and its constructions via branes in string theory. As a by-product, we construct a G 2-brane solution corresponding to a squashed fuzzy coadjoint orbit of G 2.

  9. Finite volume effects in the chiral extrapolation of baryon masses

    NASA Astrophysics Data System (ADS)

    Lutz, M. F. M.; Bavontaweepanya, R.; Kobdaj, C.; Schwarz, K.

    2014-09-01

    We perform an analysis of the QCD lattice data on the baryon octet and decuplet masses based on the relativistic chiral Lagrangian. The baryon self-energies are computed in a finite volume at next-to-next-to-next-to-leading order (N3LO), where the dependence on the physical meson and baryon masses is kept. The number of free parameters is reduced significantly down to 12 by relying on large-Nc sum rules. Altogether we describe accurately more than 220 data points from six different lattice groups, BMW, PACS-CS, HSC, LHPC, QCDSF-UKQCD and NPLQCD. Values for all counterterms relevant at N3LO are predicted. In particular we extract a pion-nucleon sigma term of 39-1+2 MeV and a strangeness sigma term of the nucleon of σsN=84-4+28 MeV. The flavor SU(3) chiral limit of the baryon octet and decuplet masses is determined with (802±4) and (1103±6) MeV. Detailed predictions for the baryon masses as currently evaluated by the ETM lattice QCD group are made.

  10. Phase-space mass bound for fermionic dark matter from dwarf spheroidal galaxies

    NASA Astrophysics Data System (ADS)

    Di Paolo, Chiara; Nesti, Fabrizio; Villante, Francesco L.

    2018-04-01

    We reconsider the lower bound on the mass of a fermionic dark matter (DM) candidate resulting from the existence of known small dwarf spheroidal galaxies, in the hypothesis that their DM halo is constituted by degenerate fermions, with phase-space density limited by the Pauli exclusion principle. By relaxing the common assumption that the DM halo scale radius is tied to that of the luminous stellar component and by marginalizing on the unknown stellar velocity dispersion anisotropy, we prove that observations lead to rather weak constraints on the DM mass, which could be as low as tens of eV. In this scenario, however, the DM haloes would be quite large and massive, so that a bound stems from the requirement that the time of orbital decay due to dynamical friction in the hosting Milky Way DM halo is longer than their lifetime. The smallest and nearest satellites Segue I and Willman I lead to a final lower bound of m ≳ 100 eV, still weaker than previous estimates but robust and independent on the model of DM formation and decoupling. We thus show that phase-space constraints do not rule out the possibility of sub-keV fermionic DM.

  11. Octet baryon masses and sigma terms from an SU(3) chiral extrapolation

    NASA Astrophysics Data System (ADS)

    Young, R. D.; Thomas, A. W.

    2010-01-01

    We report an analysis of the impressive new lattice simulation results for octet baryon masses in 2+1-flavor QCD. The analysis is based on a low-order expansion about the chiral SU(3) limit in which the symmetry breaking arises from terms linear in the quark masses plus the variation of the Goldstone boson masses in the leading chiral loops. The baryon masses evaluated at the physical light-quark masses are in remarkable agreement with the experimental values, with a model dependence considerably smaller than the rather small statistical uncertainty. From the mass formulas one can evaluate the sigma commutators for all octet baryons. This yields an accurate value for the pion-nucleon sigma commutator. It also yields the first determination of the strangeness sigma term based on 2+1-flavor lattice QCD and, in general, the sigma commutators provide a resolution to the difficult issue of fine-tuning the strange-quark mass.

  12. Loop suppressed light fermion masses with U (1 )R gauge symmetry

    NASA Astrophysics Data System (ADS)

    Nomura, Takaaki; Okada, Hiroshi

    2017-07-01

    We propose a model with a two-Higgs doublet, where quark and charged-lepton masses in the first and second families are induced at one-loop level, and neutrino masses are induced at the two-loop level. In our model, we introduce an extra U (1 )R gauge symmetry that plays a crucial role in achieving desired terms in no conflict with anomaly cancellation. We show the mechanism to generate fermion masses, the resultant mass matrices, and Yukawa interactions in mass eigenstates, and we discuss several interesting phenomenologies such as the muon anomalous magnetic dipole moment and the dark matter candidate that arise from this model.

  13. Enantiomeric Profiling of Chiral Pharmacologically Active Compounds in the Environment with the Usage of Chiral Liquid Chromatography 
Coupled with Tandem Mass Spectrometry

    PubMed Central

    Camacho-Muñoz, Dolores; Petrie, Bruce; Castrignanò, Erika; Kasprzyk-Hordern, Barbara

    2016-01-01

    The issue of drug chirality is attracting increasing attention among the scientific community. The phenomenon of chirality has been overlooked in environmental research (environmental occurrence, fate and toxicity) despite the great impact that chiral pharmacologically active compounds (cPACs) can provoke on ecosystems. The aim of this paper is to introduce the topic of chirality and its implications in environmental contamination. Special attention has been paid to the most recent advances in chiral analysis based on liquid chromatography coupled with mass spectrometry and the most popular protein based chiral stationary phases. Several groups of cPACs of environmental relevance, such as illicit drugs, human and veterinary medicines were discussed. The increase in the number of papers published in the area of chiral environmental analysis indicates that researchers are actively pursuing new opportunities to provide better understanding of environmental impacts resulting from the enantiomerism of cPACs. PMID:27713682

  14. Effective Mass Calculations for Two-dimensional Gas of Dipolar Fermions

    NASA Astrophysics Data System (ADS)

    Seydi, I.; Abedinpour, S. H.; Tanatar, B.

    2017-06-01

    We consider a two-dimensional system of ultracold dipolar fermions with dipole moments aligned in the perpendicular direction. We use the static structure factor information from Fermi-Hypernetted-Chain calculations to obtain the effective many-body dipole-dipole interaction and calculate the many-body effective mass of the system within the G0W approximation to the self-energy. A large cancellation between different contributions to the self-energy results in a weak dependence of the effective mass on the interaction strength over a large range of coupling constants.

  15. From bosonic topological transition to symmetric fermion mass generation

    NASA Astrophysics Data System (ADS)

    You, Yi-Zhuang; He, Yin-Chen; Vishwanath, Ashvin; Xu, Cenke

    2018-03-01

    A bosonic topological transition (BTT) is a quantum critical point between the bosonic symmetry-protected topological phase and the trivial phase. In this work, we investigate such a transition in a (2+1)-dimensional lattice model with the maximal microscopic symmetry: an internal SO (4 ) symmetry. We derive a description for this transition in terms of compact quantum electrodynamics (QED) with four fermion flavors (Nf=4 ). Within a systematic renormalization group analysis, we identify the critical point with the desired O (4 ) emergent symmetry and all expected deformations. By lowering the microscopic symmetry, we recover the previous Nf=2 noncompact QED description of the BTT. Finally, by merging two BTTs we recover a previously discussed theory of symmetric mass generation, as an SU (2 ) quantum chromodynamics-Higgs theory with Nf=4 flavors of SU (2 ) fundamental fermions and one SU (2 ) fundamental Higgs boson. This provides a consistency check on both theories.

  16. Chiral Magnetic Effect in Condensed Matters

    NASA Astrophysics Data System (ADS)

    Li, Qiang

    The chiral magnetic effect is the generation of electrical current induced by chirality imbalance in the presence of magnetic field. It is a macroscopic manifestation of the quantum chiral anomaly in systems possessing charged chiral fermions. In quark-gluon plasma containing nearly massless quarks, the chirality imbalance is sourced by the topological transitions. In condensed matter systems, the chiral quasiparticles emerge in the 3D Dirac and Weyl semimetals having a linear dispersion relation. Recently, the chiral magnetic effect was discovered in a 3D Dirac semimetal - zirconium pentatelluride, ZrTe5, in which a large negative magnetoresistance is observed when magnetic field is parallel with the current. It is now reported in more than a dozen Dirac and Weyl semimetals. Broadly speaking, the chiral magnetic effect can exist in a variety of condensed matters. In some cases, a material may be transformed into a Weyl semimetal by magnetic field, exhibiting the chiral magnetic effect. In other cases, the chiral magnetic current may be generated in magnetic Dirac semimetals without external magnetic field, or in asymmetric Weyl semimetals without electric field where only a magnetic field and the source of chiral quasipartiles would be necessary. In the limit of conserved quasiparticle chirality, charge transport by the chiral magnetic current is non-dissipative. The powerful notion of chirality, originally discovered in high-energy and nuclear physics, holds promise in new ways of transmitting and processing information and energy. At the same time, chiral materials have opened a fascinating possibility to study the quantum dynamics of relativistic field theory in condensed matter experiments.

  17. Unexpected mass acquisition of Dirac fermions at the quantum phase transition of a topological insulator

    NASA Astrophysics Data System (ADS)

    Sato, T.; Segawa, Kouji; Kosaka, K.; Souma, S.; Nakayama, K.; Eto, K.; Minami, T.; Ando, Yoichi; Takahashi, T.

    2011-11-01

    The three-dimensional (3D) topological insulator is a novel quantum state of matter where an insulating bulk hosts a linearly dispersing surface state, which can be viewed as a sea of massless Dirac fermions protected by the time-reversal symmetry (TRS). Breaking the TRS by a magnetic order leads to the opening of a gap in the surface state, and consequently the Dirac fermions become massive. It has been proposed theoretically that such a mass acquisition is necessary to realize novel topological phenomena, but achieving a sufficiently large mass is an experimental challenge. Here we report an unexpected discovery that the surface Dirac fermions in a solid-solution system TlBi(S1-xSex)2 acquire a mass without explicitly breaking the TRS. We found that this system goes through a quantum phase transition from the topological to the non-topological phase, and, by tracing the evolution of the electronic states using the angle-resolved photoemission, we observed that the massless Dirac state in TlBiSe2 switches to a massive state before it disappears in the non-topological phase. This result suggests the existence of a condensed-matter version of the `Higgs mechanism' where particles acquire a mass through spontaneous symmetry breaking.

  18. Anisotropic Weyl fermions from the quasiparticle excitation spectrum of a 3D Fulde-Ferrell superfluid.

    PubMed

    Xu, Yong; Chu, Rui-Lin; Zhang, Chuanwei

    2014-04-04

    Weyl fermions, first proposed for describing massless chiral Dirac fermions in particle physics, have not been observed yet in experiments. Recently, much effort has been devoted to explore Weyl fermions around band touching points of single-particle energy dispersions in certain solid state materials (named Weyl semimetals), similar as graphene for Dirac fermions. Here we show that such Weyl semimetals also exist in the quasiparticle excitation spectrum of a three-dimensional spin-orbit-coupled Fulde-Ferrell superfluid. By varying Zeeman fields, the properties of Weyl fermions, such as their creation and annihilation, number and position, as well as anisotropic linear dispersions around band touching points, can be tuned. We study the manifestation of anisotropic Weyl fermions in sound speeds of Fulde-Ferrell fermionic superfluids, which are detectable in experiments.

  19. I. Aspects of the Dark Matter Problem. II. Fermion Balls

    NASA Astrophysics Data System (ADS)

    Tetradis, Nikolaos Athanassiou

    The first part of this thesis deals with the dark matter problem. A simple non-supersymmetric extension of the standard model is presented, which provides dark matter candidates not excluded by the existing dark matter searches. The simplest candidate is the neutral component of a zero hypercharge triplet, with vector gauge interactions. The upper bound on its mass is a few TeV. We also discuss possible modifications of the standard freeze-out scenario, induced by the presence of a phase transition. More specifically, if the critical temperature of the electroweak phase transition is sufficiently small, it can change the final abundances of heavy dark matter particles, by keeping them massless for a long time. Recent experimental bounds on the Higgs mass from LEP imply that this is not the case in the minimal standard model. In the second part we discuss non-trivial configurations, involving fermions which obtain their mass through Yukawa interactions with a scalar field. Under certain conditions, the vacuum expectation value of the scalar field is shifted from the minimum of the effective potential, in regions of high fermion density. This may result in the formation of fermion bound states. We study two such cases: (a) Using the non-linear SU(3)L times SU(3)R chiral Lagrangian coupled to a field theory of nuclear forces, we show that a bound state of baryons with a well defined surface may concievably form in the presence of kaon condensation. This state is of similar density to ordinary nuclei, but has net strangeness equal to about two thirds the baryon number. We discuss the properties of lumps of strange baryon matter with baryon number between ~20 and ~10 57 where gravitational effects become important. (b) The Higgs field near a very heavy top quark or any other heavy fermion is expected to be significantly deformed. By computing explicit solutions of the classical equations of motion for a spherically symmetric configuration without gauge fields, we show

  20. Anomalous chiral transport in heavy ion collisions from Anomalous-Viscous Fluid Dynamics

    NASA Astrophysics Data System (ADS)

    Shi, Shuzhe; Jiang, Yin; Lilleskov, Elias; Liao, Jinfeng

    2018-07-01

    Chiral anomaly is a fundamental aspect of quantum theories with chiral fermions. How such microscopic anomaly manifests itself in a macroscopic many-body system with chiral fermions, is a highly nontrivial question that has recently attracted significant interest. As it turns out, unusual transport currents can be induced by chiral anomaly under suitable conditions in such systems, with the notable example of the Chiral Magnetic Effect (CME) where a vector current (e.g. electric current) is generated along an external magnetic field. A lot of efforts have been made to search for CME in heavy ion collisions, by measuring the charge separation effect induced by the CME transport. A crucial challenge in such effort, is the quantitative prediction for the CME signal. In this paper, we develop the Anomalous-Viscous Fluid Dynamics (AVFD) framework, which implements the anomalous fluid dynamics to describe the evolution of fermion currents in QGP, on top of the neutral bulk background described by the VISH2+1 hydrodynamic simulations for heavy ion collisions. With this new tool, we quantitatively and systematically investigate the dependence of the CME signal to a series of theoretical inputs and associated uncertainties. With realistic estimates of initial conditions and magnetic field lifetime, the predicted CME signal is quantitatively consistent with measured change separation data in 200GeV Au-Au collisions. Based on analysis of Au-Au collisions, we further make predictions for the CME observable to be measured in the planned isobaric (Ru-Ru v.s. Zr-Zr) collision experiment, which could provide a most decisive test of the CME in heavy ion collisions.

  1. On the chiral magnetic effect in Weyl superfluid 3He-A

    NASA Astrophysics Data System (ADS)

    Volovik, G. E.

    2017-01-01

    In the theory of the chiral anomaly in relativistic quantum field theories (RQFTs), some results depend on a regularization scheme at ultraviolet. In the chiral superfluid 3He-A, which contains two Weyl points and also experiences the effects of chiral anomaly, the "trans-Planckian" physics is known and the results can be obtained without regularization. We discuss this on example of the chiral magnetic effect (CME), which has been observed in 3He-A in the 1990s [1]. There are two forms of the contribution of the CME to the Chern-Simons term in free energy, perturbative and non-perturbative. The perturbative term comes from the fermions living in the vicinity of the Weyl point, where the fermions are "relativistic" and obey the Weyl equation. The non-perturbative term originates from the deep vacuum, being determined by the separation of the two Weyl points in momentum space. Both terms are obtained using the Adler-Bell-Jackiw equation for chiral anomaly, and both agree with the results of the microscopic calculations in the "trans-Planckian" region. Existence of the two nonequivalent forms of the Chern-Simons term demonstrates that the results obtained within the RQFT depend on the specific properties of the underlying quantum vacuum and may reflect different physical phenomena in the same vacuum.

  2. Analysis of chirality by femtosecond laser ionization mass spectrometry.

    PubMed

    Horsch, Philipp; Urbasch, Gunter; Weitzel, Karl-Michael

    2012-09-01

    Recent progress in the field of chirality analysis employing laser ionization mass spectrometry is reviewed. Emphasis is given to femtosecond (fs) laser ionization work from the author's group. We begin by reviewing fundamental aspects of determining circular dichroism (CD) in fs-laser ionization mass spectrometry (fs-LIMS) discussing an example from the literature (resonant fs-LIMS of 3-methylcyclopentanone). Second, we present new data indicating CD in non-resonant fs-LIMS of propylene oxide. Copyright © 2012 Wiley Periodicals, Inc., A Wiley Company.

  3. Taste symmetry breaking with hypercubic-smeared staggered fermions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bae, Taegil; Adams, David H.; Kim, Hyung-Jin

    2008-05-01

    We study the impact of hypercubic (HYP) smearing on the size of taste-breaking for staggered fermions, comparing to unimproved and to asqtad-improved staggered fermions. As in previous studies, we find a substantial reduction in taste-breaking compared to unimproved staggered fermions (by a factor of 4-7 on lattices with spacing a{approx_equal}0.1 fm). In addition, we observe that discretization effects of next-to-leading order in the chiral expansion (O(a{sup 2}p{sup 2})) are markedly reduced by HYP smearing. Compared to asqtad valence fermions, we find that taste-breaking in the pion spectrum is reduced by a factor of 2.5-3, down to a level comparable tomore » the expected size of generic O(a{sup 2}) effects. Our results suggest that, once one reaches a lattice spacing of a{approx_equal}0.09 fm, taste-breaking will be small enough after HYP smearing that one can use a modified power counting in which O(a{sup 2})<

  4. Low energy constants of S U ( 2 ) partially quenched chiral perturbation theory from N f = 2 + 1 domain wall QCD

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boyle, P. A.; Christ, N. H.; Garron, N.

    2016-03-09

    Here, we have performed fits of the pseudoscalar masses and decay constants, from a variety of the RBC-UKQCD Collaboration’s domain wall fermion ensembles, to SU(2) partially quenched chiral perturbation theory at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO). We report values for 9 NLO and 8 linearly independent combinations of NNLO partially quenched low-energy constants, which we compare to other lattice and phenomenological determinations. We discuss the size of successive terms in the chiral expansion and use our large set of low-energy constants to make predictions for mass splittings due to QCD isospin-breaking effects and the S-wave ππ scattering lengths.more » Lastly, we conclude that, for the range of pseudoscalar masses explored in this work, 115 MeV≲mPS≲430 MeV, the NNLO SU(2) expansion is quite robust and can fit lattice data with percent-scale accuracy.« less

  5. Magnetotransport in Dirac metals: Chiral magnetic effect and quantum oscillations

    DOE PAGES

    Monteiro, Gustavo M.; Abanov, Alexander G.; Kharzeev, Dmitri E.

    2015-10-08

    Dirac metals are characterized by the linear dispersion of fermionic quasiparticles, with the Dirac point hidden inside a Fermi surface. We study the magnetotransport in these materials using chiral kinetic theory to describe within the same framework both the negative magnetoresistance caused by the chiral magnetic effect and quantum oscillations in the magnetoresistance due to the existence of the Fermi surface. Lastly, we discuss the relevance of obtained results to recent measurements on Cd 3As 2.

  6. Exotic meson decays in the environment with chiral imbalance

    NASA Astrophysics Data System (ADS)

    Andrianov, A. A.; Andrianov, V. A.; Espriu, D.; Iakubovich, A. V.; Putilova, A. E.

    2017-10-01

    An emergence of Local Parity Breaking (LPB) in central heavy-ion collisions (HIC) at high energies is discussed. LPB in the fireball can be produced by a difference between the number densities of right- and left-handed chiral fermions (Chiral Imbalance) which is implemented by a chiral (axial) chemical potential. The effective meson lagrangian induced by QCD is extended to the medium with Chiral Imbalance and the properties of light scalar and pseudoscalar mesons (π, α0) are analyzed. It is shown that exotic decays of scalar mesons arise as a result of mixing of π and α0 vacuum states in the presence of chiral imbalance. The pion electromagnetic formfactor obtains an unusual parity-odd supplement which generates a photon polarization asymmetry in pion polarizability. We hope that the above pointed indications of LPB can be identified in experiments on LHC, RHIC, CBM FAIR and NICA accelerators.

  7. Birefringent breakup of Dirac fermions on a square optical lattice

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kennett, Malcolm P.; Komeilizadeh, Nazanin; Kaveh, Kamran

    2011-05-15

    We introduce a lattice model for fermions in a spatially periodic magnetic field that also has spatially periodic hopping amplitudes. We discuss how this model might be realized with cold atoms in an artificial magnetic field on a square optical lattice. When there is an average flux of half a flux quantum per plaquette, the spectrum of low-energy excitations can be described by massless Dirac fermions in which the usually doubly degenerate Dirac cones split into cones with different ''speeds of light.'' These gapless birefringent Dirac fermions arise because of broken chiral symmetry in the kinetic energy term of themore » effective low-energy Hamiltonian. We characterize the effects of various perturbations to the low-energy spectrum, including staggered potentials, interactions, and domain-wall topological defects.« less

  8. Chiral effective theory of dark matter direct detection

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bishara, Fady; Brod, Joachim; Grinstein, Benjamin

    2017-02-01

    We present the effective field theory for dark matter interactions with the visible sector that is valid at scales of O(1 GeV). Starting with an effective theory describing the interactions of fermionic and scalar dark matter with quarks, gluons and photons via higher dimension operators that would arise from dimension-five and dimension-six operators above electroweak scale, we perform a nonperturbative matching onto a heavy baryon chiral perturbation theory that describes dark matter interactions with light mesons and nucleons. This is then used to obtain the coefficients of the nuclear response functions using a chiral effective theory description of nuclear forces.more » Our results consistently keep the leading contributions in chiral counting for each of the initial Wilson coefficients.« less

  9. One-loop perturbative coupling of A and A? through the chiral overlap operator

    NASA Astrophysics Data System (ADS)

    Makino, Hiroki; Morikawa, Okuto; Suzuki, Hiroshi

    2018-03-01

    Recently, Grabowska and Kaplan constructed a four-dimensional lattice formulation of chiral gauge theories on the basis of the chiral overlap operator. At least in the tree-level approximation, the left-handed fermion is coupled only to the original gauge field A, while the right-handed one is coupled only to the gauge field A*, a deformation of A by the gradient flow with infinite flow time. In this paper, we study the fermion one-loop effective action in their formulation. We show that the continuum limit of this effective action contains local interaction terms between A and A*, even if the anomaly cancellation condition is met. These non-vanishing terms would lead an undesired perturbative spectrum in the formulation.

  10. On lattice chiral gauge theories

    NASA Technical Reports Server (NTRS)

    Maiani, L.; Rossi, G. C.; Testa, M.

    1991-01-01

    The Smit-Swift-Aoki formulation of a lattice chiral gauge theory is presented. In this formulation the Wilson and other non invariant terms in the action are made gauge invariant by the coupling with a nonlinear auxilary scalar field, omega. It is shown that omega decouples from the physical states only if appropriate parameters are tuned so as to satisfy a set of BRST identities. In addition, explicit ghost fields are necessary to ensure decoupling. These theories can give rise to the correct continuum limit. Similar considerations apply to schemes with mirror fermions. Simpler cases with a global chiral symmetry are discussed and it is shown that the theory becomes free at decoupling. Recent numerical simulations agree with those considerations.

  11. A quenched study of the Schrödinger functional with chirally rotated boundary conditions: Applications

    NASA Astrophysics Data System (ADS)

    González López, J.; Jansen, K.; Renner, D. B.; Shindler, A.

    2013-02-01

    In a previous paper (González López, et al., 2013) [1], we have discussed the non-perturbative tuning of the chirally rotated Schrödinger functional (χSF). This tuning is required to eliminate bulk O(a) cutoff effects in physical correlation functions. Using our tuning results obtained in González López et al. (2013) [1] we perform scaling and universality tests analyzing the residual O(a) cutoff effects of several step-scaling functions and we compute renormalization factors at the matching scale. As an example of possible application of the χSF we compute the renormalized strange quark mass using large volume data obtained from Wilson twisted mass fermions at maximal twist.

  12. Laser R2PI spectroscopic and mass spectrometric studies of chiral neurotransmitters

    NASA Astrophysics Data System (ADS)

    Giardini, A.; Marotta, V.; Paladini, A.; Piccirillo, S.; Rondino, F.; Satta, M.; Speranza, M.

    2007-07-01

    One color, mass selected resonant two-photon ionization (1cR2PI) spectra of supersonically expanded bare neurotransmitter, (1 S,2 S)-(+)- N-methyl pseudoephedrine (MPE), and its complexes with chiral and achiral molecules have been investigated. The excitation spectrum of bare MPE has been analyzed and discussed on the basis of theoretical predictions at the B3LYP/6-31G** level of theory. The results allowed to get information on the possible conformers of MPE molecule and on the intermolecular forces on its cluster formed with a variety of solvent molecules, including chiral alcohols, lactates and water. Further information on intermolecular interactions have been obtained with ESI-CID-MS 2 technique, applied to chiral biomolecules linked through a metal ion to the neurotransmitter. The experimental results are compared with theoretical predictions.

  13. Bosonization of free Weyl fermions

    NASA Astrophysics Data System (ADS)

    Marino, E. C.

    2017-03-01

    We generalize the method of bosonization, in its complete form, to a spacetime with 3  +  1 dimensions, and apply it to free Weyl fermion fields, which thereby, can be expressed in terms of a boson field, namely the Kalb-Ramond anti-symmetric tensor gauge field. The result may have interesting consequences both in condensed matter and in particle physics. In the former, the bosonized form of the Weyl chiral currents provides a simple explanation for the angle-dependent magneto-conductance recently observed in materials known as Weyl semimetals. In the latter, conversely, since electrons can be thought of as a combination of left and right Weyl fermions, our result suggests the possibility of a unified description of the elementary particles, which undergo the fundamental interactions, with the mediators of such interactions, namely, the gauge fields. This would fulfill the pioneering attempt of Skyrme, to unify the particles with their interaction mediators (Skyrme 1962 Nucl. Phys. 31 556).

  14. Realizing three generations of the Standard Model fermions in the type IIB matrix model

    NASA Astrophysics Data System (ADS)

    Aoki, Hajime; Nishimura, Jun; Tsuchiya, Asato

    2014-05-01

    We discuss how the Standard Model particles appear from the type IIB matrix model, which is considered to be a nonperturbative formulation of superstring theory. In particular, we are concerned with a constructive definition of the theory, in which we start with finite- N matrices and take the large- N limit afterwards. In that case, it was pointed out recently that realizing chiral fermions in the model is more difficult than it had been thought from formal arguments at N = ∞ and that introduction of a matrix version of the warp factor is necessary. Based on this new insight, we show that two generations of the Standard Model fermions can be realized by considering a rather generic configuration of fuzzy S2 and fuzzy S2 × S2 in the extra dimensions. We also show that three generations can be obtained by squashing one of the S2's that appear in the configuration. Chiral fermions appear at the intersections of the fuzzy manifolds with nontrivial Yukawa couplings to the Higgs field, which can be calculated from the overlap of their wave functions.

  15. Creation of mass dimension one fermionic particles in asymptotically expanding universe

    NASA Astrophysics Data System (ADS)

    Pereira, S. H.; Lima, Rodrigo C.

    In the present work we study the process of particle creation for mass dimension one fermionic fields (sometimes named Elko) as a consequence of expansion of the universe. We study the effect driven by an expanding background that is asymptotically Minkowski in the past and future. The differential equation that governs the time mode function is obtained for the conformal coupling case and, although its solution is nonanalytic, within an approximation that preserves the characteristics of the terms that break analyticity, analytic solutions are obtained. Thus, by means of Bogolyubov transformations technique, the number density of particles created is obtained, which can be compared to exact solutions already present in literature for scalar and Dirac particles. The spectrum of the created particles was obtained and it was found that it is a generalization of the scalar field case, which converges to the scalar field one when the specific terms concerning the Elko field are dropped out. We also found that lighter Elko particles are created in larger quantities than the Dirac fermionic particles. By considering the Elko particles as candidate to the dark matter in the universe, such result shows that there are more light dark matter (Elko) particles created by the gravitational effects in the universe than baryonic (fermionic) matter, in agreement to the standard model.

  16. Neutron and proton electric dipole moments from N f=2+1 domain-wall fermion lattice QCD

    DOE PAGES

    Shintani, Eigo; Blum, Thomas; Izubuchi, Taku; ...

    2016-05-05

    We present a lattice calculation of the neutron and proton electric dipole moments (EDM’s) with N f = 2 + 1 flavors of domain-wall fermions. The neutron and proton EDM form factors are extracted from three-point functions at the next-to-leading order in the θ vacuum of QCD. In this computation, we use pion masses 330 and 420 MeV and 2.7 fm 3 lattices with Iwasaki gauge action and a 170 MeV pion and 4.6 fm 3 lattice with I-DSDR gauge action, all generated by the RBC and UKQCD collaborations. The all-mode-averaging technique enables an efficient, high statistics calculation; however themore » statistical errors on our results are still relatively large, so we investigate a new direction to reduce them, reweighting with the local topological charge density which appears promising. Furthermore, we discuss the chiral behavior and finite size effects of the EDM’s in the context of baryon chiral perturbation theory.« less

  17. One-loop perturbative coupling of A and A⊙ through the chiral overlap operator

    NASA Astrophysics Data System (ADS)

    Makino, Hiroki; Morikawa, Okuto; Suzuki, Hiroshi

    2017-06-01

    We study the one-loop effective action defined by the chiral overlap operator in the four-dimensional lattice formulation of chiral gauge theories by Grabowska and Kaplan. In the tree-level continuum limit, the left-handed component of the fermion is coupled only to the original gauge field A, while the right-handed one is coupled only to A_\\star, which is given by the gradient flow of A with infinite flow time. In this paper, we show that the continuum limit of the one-loop effective action contains local interaction terms between A and A_\\star, which do not generally vanish even if the gauge representation of the fermion is anomaly free. We argue that the presence of such interaction terms can be regarded as undesired gauge symmetry-breaking effects in the formulation.

  18. Relations between heavy-light meson and quark masses

    NASA Astrophysics Data System (ADS)

    Brambilla, N.; Komijani, J.; Kronfeld, A. S.; Vairo, A.; Tumqcd Collaboration

    2018-02-01

    The study of heavy-light meson masses should provide a way to determine renormalized quark masses and other properties of heavy-light mesons. In the context of lattice QCD, for example, it is possible to calculate hadronic quantities for arbitrary values of the quark masses. In this paper, we address two aspects relating heavy-light meson masses to the quark masses. First, we introduce a definition of the renormalized quark mass that is free of both scale dependence and renormalon ambiguities, and discuss its relation to more familiar definitions of the quark mass. We then show how this definition enters a merger of the descriptions of heavy-light masses in heavy-quark effective theory and in chiral perturbation theory (χ PT ). For practical implementations of this merger, we extend the one-loop χ PT corrections to lattice gauge theory with heavy-light mesons composed of staggered fermions for both quarks. Putting everything together, we obtain a practical formula to describe all-staggered heavy-light meson masses in terms of quark masses as well as some lattice artifacts related to staggered fermions. In a companion paper, we use this function to analyze lattice-QCD data and extract quark masses and some matrix elements defined in heavy-quark effective theory.

  19. Relations between heavy-light meson and quark masses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brambilla, N.; Komijani, J.; Kronfeld, A. S.

    Here, the study of heavy-light meson masses should provide a way to determine renormalized quark masses and other properties of heavy-light mesons. In the context of lattice QCD, for example, it is possible to calculate hadronic quantities for arbitrary values of the quark masses. In this paper, we address two aspects relating heavy-light meson masses to the quark masses. First, we introduce a definition of the renormalized quark mass that is free of both scale dependence and renormalon ambiguities, and discuss its relation to more familiar definitions of the quark mass. We then show how this definition enters a mergermore » of the descriptions of heavy-light masses in heavy-quark effective theory and in chiral perturbation theory (χPT). For practical implementations of this merger, we extend the one-loop χPT corrections to lattice gauge theory with heavy-light mesons composed of staggered fermions for both quarks. Putting everything together, we obtain a practical formula to describe all-staggered heavy-light meson masses in terms of quark masses as well as some lattice artifacts related to staggered fermions. In a companion paper, we use this function to analyze lattice-QCD data and extract quark masses and some matrix elements defined in heavy-quark effective theory.« less

  20. Relations between heavy-light meson and quark masses

    DOE PAGES

    Brambilla, N.; Komijani, J.; Kronfeld, A. S.; ...

    2018-02-07

    Here, the study of heavy-light meson masses should provide a way to determine renormalized quark masses and other properties of heavy-light mesons. In the context of lattice QCD, for example, it is possible to calculate hadronic quantities for arbitrary values of the quark masses. In this paper, we address two aspects relating heavy-light meson masses to the quark masses. First, we introduce a definition of the renormalized quark mass that is free of both scale dependence and renormalon ambiguities, and discuss its relation to more familiar definitions of the quark mass. We then show how this definition enters a mergermore » of the descriptions of heavy-light masses in heavy-quark effective theory and in chiral perturbation theory (χPT). For practical implementations of this merger, we extend the one-loop χPT corrections to lattice gauge theory with heavy-light mesons composed of staggered fermions for both quarks. Putting everything together, we obtain a practical formula to describe all-staggered heavy-light meson masses in terms of quark masses as well as some lattice artifacts related to staggered fermions. In a companion paper, we use this function to analyze lattice-QCD data and extract quark masses and some matrix elements defined in heavy-quark effective theory.« less

  1. The fermionic projector in a time-dependent external potential: Mass oscillation property and Hadamard states

    NASA Astrophysics Data System (ADS)

    Finster, Felix; Murro, Simone; Röken, Christian

    2016-07-01

    We give a non-perturbative construction of the fermionic projector in Minkowski space coupled to a time-dependent external potential which is smooth and decays faster than quadratically for large times. The weak and strong mass oscillation properties are proven. We show that the integral kernel of the fermionic projector is of the Hadamard form, provided that the time integral of the spatial sup-norm of the potential satisfies a suitable bound. This gives rise to an algebraic quantum field theory of Dirac fields in an external potential with a distinguished pure quasi-free Hadamard state.

  2. Fermion emission from a Julia-Zee dyon

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blaer, A.S.; Christ, N.H.; Tang, J.

    1982-04-15

    A relationship is obtained between the S matrix for the charge-exchange scattering of a fermion by a Julia-Zee dyon and the flux of fermions emitted by the dyon when the mass of the fermions is sufficiently small. In the limit of a pointlike dyon, the required S-matrix elements are obtained in closed form and the corresponding fermion flux is computed explicitly.

  3. Effective four-fermion operators in top physics: A roadmap

    NASA Astrophysics Data System (ADS)

    Aguilar-Saavedra, J. A.

    2011-02-01

    We write down a minimal basis for dimension-six gauge-invariant four-fermion operators, with some operator replacements with respect to previous ones which make it simpler for calculations. Using this basis we classify all four-fermion operator contributions involving one or two top quarks. Taking into account the different fermion chiralities, possible colour contractions and independent flavour combinations, a total number of 572 gauge-invariant operators are involved. We apply this to calculate all three-body top decay widths t→dud, t→dei+ν, t→uuu, t→uej+ei-, t→uνν (with i,j,k generation indices) mediated by dimension-six four-fermion operators, including the interference with the Standard Model amplitudes when present. All single top production cross sections in pp, pp¯ and ee collisions are calculated as well, namely ud→dt, dd→ut, ud→dt, uu→ut, uu→ut, ee→ut and the charge conjugate processes. We also compute all top pair production cross sections, uu→tt¯, dd→tt¯, uu→tt and ee→tt¯. Our results are completely general, without assuming any particular relation among effective operator coefficients.

  4. Observation of the chiral magnetic effect in ZrTe₅

    DOE PAGES

    Li, Qiang; Kharzeev, Dmitri E.; Zhang, Cheng; ...

    2015-02-08

    The chiral magnetic effect is the generation of electric current induced by chirality imbalance in the presence of magnetic field. It is a macroscopic manifestation of the quantum anomaly in relativistic field theory of chiral fermions (massless spin 1/2 particles with a definite projection of spin on momentum) – a dramatic phenomenon arising from a collective motion of particles and antiparticles in the Dirac sea. The recent discovery of Dirac semimetals with chiral quasi-particles opens a fascinating possibility to study this phenomenon in condensed matter experiments. Here we report on the first observation of chiral magnetic effect through the measurementmore » of magneto-transport in zirconium pentatelluride, ZrTe₅. Our angle-resolved photoemission spectroscopy experiments show that this material’s electronic structure is consistent with a 3D Dirac semimetal. We observe a large negative magnetoresistance when magnetic field is parallel with the current. The measured quadratic field dependence of the magnetoconductance is a clear indication of the chiral magnetic effect. Furthermore, the observed phenomenon stems from the effective transmutation of Dirac semimetal into a Weyl semimetal induced by the parallel electric and magnetic fields that represent a topologically nontrivial gauge field background.« less

  5. Topological responses from chiral anomaly in multi-Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Huang, Ze-Min; Zhou, Jianhui; Shen, Shun-Qing

    2017-08-01

    Multi-Weyl semimetals are a kind of topological phase of matter with discrete Weyl nodes characterized by multiple monopole charges, in which the chiral anomaly, the anomalous nonconservation of an axial current, occurs in the presence of electric and magnetic fields. Electronic transport properties related to the chiral anomaly in the presence of both electromagnetic fields and axial electromagnetic fields in multi-Weyl semimetals are systematically studied. It has been found that the anomalous Hall conductivity has a modification linear in the axial vector potential from inhomogeneous strains. The axial electric field leads to an axial Hall current that is proportional to the distance of Weyl nodes in momentum space. This axial current may generate chirality accumulation of Weyl fermions through delicately engineering the axial electromagnetic fields even in the absence of external electromagnetic fields. Therefore this work provides a nonmagnetic mechanism of generation of chirality accumulation in Weyl semimetals and might shed new light on the application of Weyl semimetals in the emerging field of valleytronics.

  6. B{sub K} with two flavors of dynamical overlap fermions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aoki, S.; Riken BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973; Fukaya, H.

    2008-05-01

    We present a two-flavor QCD calculation of B{sub K} on a 16{sup 3}x32 lattice at a{approx}0.12 fm (or equivalently a{sup -1}=1.67 GeV). Both valence and sea quarks are described by the overlap fermion formulation. The matching factor is calculated nonperturbatively with the so-called RI/MOM scheme. We find that the lattice data are well described by the next-to-leading order (NLO) partially quenched chiral perturbation theory (PQChPT) up to around a half of the strange quark mass (m{sub s}{sup phys}/2). The data at quark masses heavier than m{sub s}{sup phys}/2 are fitted including a part of next-to-next-to-leading order terms. We obtain B{submore » K}{sup MS}(2 GeV)=0.537(4)(40), where the first error is statistical and the second is an estimate of systematic uncertainties from finite volume, fixing topology, the matching factor, and the scale setting.« less

  7. Hidden charged dark matter and chiral dark radiation

    NASA Astrophysics Data System (ADS)

    Ko, P.; Nagata, Natsumi; Tang, Yong

    2017-10-01

    In the light of recent possible tensions in the Hubble constant H0 and the structure growth rate σ8 between the Planck and other measurements, we investigate a hidden-charged dark matter (DM) model where DM interacts with hidden chiral fermions, which are charged under the hidden SU(N) and U(1) gauge interactions. The symmetries in this model assure these fermions to be massless. The DM in this model, which is a Dirac fermion and singlet under the hidden SU(N), is also assumed to be charged under the U(1) gauge symmetry, through which it can interact with the chiral fermions. Below the confinement scale of SU(N), the hidden quark condensate spontaneously breaks the U(1) gauge symmetry such that there remains a discrete symmetry, which accounts for the stability of DM. This condensate also breaks a flavor symmetry in this model and Nambu-Goldstone bosons associated with this flavor symmetry appear below the confinement scale. The hidden U(1) gauge boson and hidden quarks/Nambu-Goldstone bosons are components of dark radiation (DR) above/below the confinement scale. These light fields increase the effective number of neutrinos by δNeff ≃ 0.59 above the confinement scale for N = 2, resolving the tension in the measurements of the Hubble constant by Planck and Hubble Space Telescope if the confinement scale is ≲1 eV. DM and DR continuously scatter with each other via the hidden U(1) gauge interaction, which suppresses the matter power spectrum and results in a smaller structure growth rate. The DM sector couples to the Standard Model sector through the exchange of a real singlet scalar mixing with the Higgs boson, which makes it possible to probe our model in DM direct detection experiments. Variants of this model are also discussed, which may offer alternative ways to investigate this scenario.

  8. Low-lying baryon spectrum with two dynamical twisted mass fermions

    NASA Astrophysics Data System (ADS)

    Alexandrou, C.; Baron, R.; Carbonell, J.; Drach, V.; Guichon, P.; Jansen, K.; Korzec, T.; Pène, O.

    2009-12-01

    The masses of the low-lying baryons are evaluated using two degenerate flavors of twisted mass sea quarks corresponding to pseudoscalar masses in the range of about 270-500 MeV. The strange valence quark mass is tuned to reproduce the mass of the kaon in the physical limit. The tree-level Symanzik improved gauge action is employed. We use lattices of spatial size 2.1 and 2.7 fm at two values of the lattice spacing with r0/a=5.22(2) and r0/a=6.61(3). We check for both finite volume and cutoff effects on the baryon masses. We performed a detailed study of the chiral extrapolation of the octet and decuplet masses using SU(2) χPT. The lattice spacings determined using the nucleon mass at the physical point are consistent with the values extracted using the pion decay constant. We examine the issue of isospin symmetry breaking for the octet and decuplet baryons and its dependence on the lattice spacing. We show that in the continuum limit isospin breaking is consistent with zero, as expected. The baryon masses that we find after taking the continuum limit and extrapolating to the physical limit are in good agreement with experiment.

  9. Masses and sigma terms of doubly charmed baryons up to O (p4) in manifestly Lorentz-invariant baryon chiral perturbation theory

    NASA Astrophysics Data System (ADS)

    Yao, De-Liang

    2018-02-01

    We calculate the masses and sigma terms of the doubly charmed baryons up to next-to-next-to-next-to-leading order [i.e., O (p4) ] in a covariant baryon chiral perturbation theory by using the extended-on-mass-shell renormalization scheme. Their expressions both in infinite and finite volumes are provided for chiral extrapolation in lattice QCD. As a first application, our chiral results of the masses are confronted with the existing lattice QCD data in the presence of finite-volume corrections. Up to O (p3) , all relevant low-energy constants can be well determined. As a consequence, we obtain the physical values for the masses of Ξc c and Ωc c baryons by extrapolating to the physical limit. Our determination of the Ξc c mass is consistent with the recent experimental value by LHCb Collaboration, however, larger than the one by SELEX Collaboration. In addition, we predict the pion-baryon and strangeness-baryon sigma terms, as well as the mass splitting between the Ξc c and Ωc c states. Their quark mass dependences are also discussed. The numerical procedure can be applied to the chiral results of O (p4) order, where more unknown constants are involved, when more data are available for unphysical pion masses.

  10. Charged fermions below 100 GeV

    NASA Astrophysics Data System (ADS)

    Egana-Ugrinovic, Daniel; Low, Matthew; Ruderman, Joshua T.

    2018-05-01

    How light can a fermion be if it has unit electric charge? We revisit the lore that LEP robustly excludes charged fermions lighter than about 100 GeV. We review LEP chargino searches, and find them to exclude charged fermions lighter than 90 GeV, assuming a higgsino-like cross section. However, if the charged fermion couples to a new scalar, destructive interference among production channels can lower the LEP cross section by a factor of 3. In this case, we find that charged fermions as light as 75 GeV can evade LEP bounds, while remaining consistent with constraints from the LHC. As the LHC collects more data, charged fermions in the 75-100 GeV mass range serve as a target for future monojet and disappearing track searches.

  11. Magnetic fields and chiral asymmetry in the early hot universe

    NASA Astrophysics Data System (ADS)

    Sydorenko, Maksym; Tomalak, Oleksandr; Shtanov, Yuri

    2016-10-01

    In this paper, we study analytically the process of external generation and subsequent free evolution of the lepton chiral asymmetry and helical magnetic fields in the early hot universe. This process is known to be affected by the Abelian anomaly of the electroweak gauge interactions. As a consequence, chiral asymmetry in the fermion distribution generates magnetic fields of non-zero helicity, and vice versa. We take into account the presence of thermal bath, which serves as a seed for the development of instability in magnetic field in the presence of externally generated lepton chiral asymmetry. The developed helical magnetic field and lepton chiral asymmetry support each other, considerably prolonging their mutual existence, in the process of `inverse cascade' transferring magnetic-field power from small to large spatial scales. For cosmologically interesting initial conditions, the chiral asymmetry and the energy density of helical magnetic field are shown to evolve by scaling laws, effectively depending on a single combined variable. In this case, the late-time asymptotics of the conformal chiral chemical potential reproduces the universal scaling law previously found in the literature for the system under consideration. This regime is terminated at lower temperatures because of scattering of electrons with chirality change, which exponentially washes out chiral asymmetry. We derive an expression for the termination temperature as a function of the chiral asymmetry and energy density of helical magnetic field.

  12. Laminar and Turbulent Dynamos in Chiral Magnetohydrodynamics. II. Simulations

    NASA Astrophysics Data System (ADS)

    Schober, Jennifer; Rogachevskii, Igor; Brandenburg, Axel; Boyarsky, Alexey; Fröhlich, Jürg; Ruchayskiy, Oleg; Kleeorin, Nathan

    2018-05-01

    Using direct numerical simulations (DNS), we study laminar and turbulent dynamos in chiral magnetohydrodynamics with an extended set of equations that accounts for an additional contribution to the electric current due to the chiral magnetic effect (CME). This quantum phenomenon originates from an asymmetry between left- and right-handed relativistic fermions in the presence of a magnetic field and gives rise to a chiral dynamo. We show that the magnetic field evolution proceeds in three stages: (1) a small-scale chiral dynamo instability, (2) production of chiral magnetically driven turbulence and excitation of a large-scale dynamo instability due to a new chiral effect (α μ effect), and (3) saturation of magnetic helicity and magnetic field growth controlled by a conservation law for the total chirality. The α μ effect becomes dominant at large fluid and magnetic Reynolds numbers and is not related to kinetic helicity. The growth rate of the large-scale magnetic field and its characteristic scale measured in the numerical simulations agree well with theoretical predictions based on mean-field theory. The previously discussed two-stage chiral magnetic scenario did not include stage (2), during which the characteristic scale of magnetic field variations can increase by many orders of magnitude. Based on the findings from numerical simulations, the relevance of the CME and the chiral effects revealed in the relativistic plasma of the early universe and of proto-neutron stars are discussed.

  13. New vector-like fermions and flavor physics

    DOE PAGES

    Ishiwata, Koji; Ligeti, Zoltan; Wise, Mark B.

    2015-10-06

    We study renormalizable extensions of the standard model that contain vector-like fermions in a (single) complex representation of the standard model gauge group. There are 11 models where the vector-like fermions Yukawa couple to the standard model fermions via the Higgs field. These models do not introduce additional fine-tunings. They can lead to, and are constrained by, a number of different flavor-changing processes involving leptons and quarks, as well as direct searches. An interesting feature of the models with strongly interacting vector-like fermions is that constraints from neutral meson mixings (apart from CP violation inmore » $$ {K}^0-{\\overline{K}}^0 $$ mixing) are not sensitive to higher scales than other flavor-changing neutral-current processes. We identify order 1/(4πM) 2 (where M is the vector-like fermion mass) one-loop contributions to the coefficients of the four-quark operators for meson mixing, that are not suppressed by standard model quark masses and/or mixing angles.« less

  14. The Chiral Separation Effect in quenched finite-density QCD

    NASA Astrophysics Data System (ADS)

    Puhr, Matthias; Buividovich, Pavel

    2018-03-01

    We present results of a study of the Chiral Separation Effect (CSE) in quenched finite-density QCD. Using a recently developed numerical method we calculate the conserved axial current for exactly chiral overlap fermions at finite density for the first time. We compute the anomalous transport coeffcient for the CSE in the confining and deconfining phase and investigate possible deviations from the universal value. In both phases we find that non-perturbative corrections to the CSE are absent and we reproduce the universal value for the transport coeffcient within small statistical errors. Our results suggest that the CSE can be used to determine the renormalisation factor of the axial current.

  15. Gaps, Pseudogaps, and the Nature of Charge in Holographic Fermion Models

    NASA Astrophysics Data System (ADS)

    Vanacore, Garrett; Phillips, Philip

    Building on prior holographic constructions of Fermi arcs and Mott physics, we investigate the landscape of gapped and gapless strongly-correlated phases resulting from bulk fermion interactions in gauge/gravity duality. We test a proposed connection between bulk chiral symmetry and gapless boundary states, and discuss implications for discrete symmetry breaking in pseudogapped systems like the cuprate superconductors. Numerical methods are used to treat gravitational backreaction of bulk fermions, allowing more rigorous investigation of the existence of holographic Fermi surfaces and their adherence to Luttinger's rule. We use these techniques to study deviations from Luttinger's rule in holography, testing a recent claim that momentum-deconfined charges are at the heart of the Mott state.

  16. Universal relations with fermionic dark matter

    NASA Astrophysics Data System (ADS)

    Krut, A.; Argüelles, C. R.; Rueda, J. A.; Ruffini, R.

    2018-01-01

    We have recently introduced a new model for the distribution of dark matter (DM) in galaxies, the Ruffini-Argüelles-Rueda (RAR) model, based on a self-gravitating system of massive fermions at finite temperatures. The RAR model, for fermion masses above keV, successfully describes the DM halos in galaxies, and predicts the existence of a denser quantum core towards the center of each configuration. We demonstrate here, for the first time, that the introduction of a cutoff in the fermion phase-space distribution, necessary to account for galaxies finite size and mass, defines a new solution with a compact quantum core which represents an alternative to the central black hole (BH) scenario for SgrA*. For a fermion mass in the range 48keV ≤ mc2 ≤ 345keV, the DM halo distribution fulfills the most recent data of the Milky Way rotation curves while harbors a dense quantum core of 4×106M⊙ within the S2 star pericenter. In particular, for a fermion mass of mc2 ˜ 50keV the model is able to explain the DM halos from typical dwarf spheroidal to normal elliptical galaxies, while harboring dark and massive compact objects from ˜ 103M⊙ tp to 108M⊙ at their respective centers. The model is shown to be in good agreement with different observationally inferred universal relations, such as the ones connecting DM halos with supermassive dark central objects. Finally, the model provides a natural mechanism for the formation of supermassive BHs as heavy as few ˜ 108M⊙. We argue that larger BH masses (few ˜ 109-10M⊙) may be achieved by assuming subsequent accretion processes onto the above heavy seeds, depending on accretion efficiency and environment.

  17. Topology and strong four fermion interactions in four dimensions

    NASA Astrophysics Data System (ADS)

    Catterall, Simon; Butt, Nouman

    2018-05-01

    We study massless fermions interacting through a particular four-fermion term in four dimensions. Exact symmetries prevent the generation of bilinear fermion mass terms. We determine the structure of the low-energy effective action for the auxiliary field needed to generate the four-fermion term and find it has an novel structure that admits topologically nontrivial defects with nonzero Hopf invariant. We show that fermions propagating in such a background pick up a mass without breaking symmetries. Furthermore, pairs of such defects experience a logarithmic interaction. We argue that a phase transition separates a phase where these defects proliferate from a broken phase where they are bound tightly. We conjecture that, by tuning one additional operator, the broken phase can be eliminated with a single BKT-like phase transition separating the massless from massive phases.

  18. Magnetic fields and chiral asymmetry in the early hot universe

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sydorenko, Maksym; Shtanov, Yuri; Tomalak, Oleksandr, E-mail: maxsydorenko@gmail.com, E-mail: tomalak@uni-mainz.de, E-mail: shtanov@bitp.kiev.ua

    In this paper, we study analytically the process of external generation and subsequent free evolution of the lepton chiral asymmetry and helical magnetic fields in the early hot universe. This process is known to be affected by the Abelian anomaly of the electroweak gauge interactions. As a consequence, chiral asymmetry in the fermion distribution generates magnetic fields of non-zero helicity, and vice versa. We take into account the presence of thermal bath, which serves as a seed for the development of instability in magnetic field in the presence of externally generated lepton chiral asymmetry. The developed helical magnetic field andmore » lepton chiral asymmetry support each other, considerably prolonging their mutual existence, in the process of 'inverse cascade' transferring magnetic-field power from small to large spatial scales. For cosmologically interesting initial conditions, the chiral asymmetry and the energy density of helical magnetic field are shown to evolve by scaling laws, effectively depending on a single combined variable. In this case, the late-time asymptotics of the conformal chiral chemical potential reproduces the universal scaling law previously found in the literature for the system under consideration. This regime is terminated at lower temperatures because of scattering of electrons with chirality change, which exponentially washes out chiral asymmetry. We derive an expression for the termination temperature as a function of the chiral asymmetry and energy density of helical magnetic field.« less

  19. Dynamic origins of fermionic D -terms

    NASA Astrophysics Data System (ADS)

    Hudson, Jonathan; Schweitzer, Peter

    2018-03-01

    The D -term is defined through matrix elements of the energy-momentum tensor, similarly to mass and spin, yet this important particle property is experimentally not known any fermion. In this work we show that the D -term of a spin 1/2 fermion is of dynamical origin: it vanishes for a free fermion. This is in pronounced contrast to the bosonic case where already a free spin-0 boson has a non-zero intrinsic D -term. We illustrate in two simple models how interactions generate the D -term of a fermion with an internal structure, the nucleon. All known matter is composed of elementary fermions. This indicates the importance to study this interesting particle property in more detail, which will provide novel insights especially on the structure of the nucleon.

  20. Laminar and Turbulent Dynamos in Chiral Magnetohydrodynamics. I. Theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rogachevskii, Igor; Kleeorin, Nathan; Ruchayskiy, Oleg

    2017-09-10

    The magnetohydrodynamic (MHD) description of plasmas with relativistic particles necessarily includes an additional new field, the chiral chemical potential associated with the axial charge (i.e., the number difference between right- and left-handed relativistic fermions). This chiral chemical potential gives rise to a contribution to the electric current density of the plasma ( chiral magnetic effect ). We present a self-consistent treatment of the chiral MHD equations , which include the back-reaction of the magnetic field on a chiral chemical potential and its interaction with the plasma velocity field. A number of novel phenomena are exhibited. First, we show that themore » chiral magnetic effect decreases the frequency of the Alfvén wave for incompressible flows, increases the frequencies of the Alfvén wave and of the fast magnetosonic wave for compressible flows, and decreases the frequency of the slow magnetosonic wave. Second, we show that, in addition to the well-known laminar chiral dynamo effect, which is not related to fluid motions, there is a dynamo caused by the joint action of velocity shear and chiral magnetic effect. In the presence of turbulence with vanishing mean kinetic helicity, the derived mean-field chiral MHD equations describe turbulent large-scale dynamos caused by the chiral alpha effect, which is dominant for large fluid and magnetic Reynolds numbers. The chiral alpha effect is due to an interaction of the chiral magnetic effect and fluctuations of the small-scale current produced by tangling magnetic fluctuations (which are generated by tangling of the large-scale magnetic field by sheared velocity fluctuations). These dynamo effects may have interesting consequences in the dynamics of the early universe, neutron stars, and the quark–gluon plasma.« less

  1. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators

    DOE PAGES

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P.

    2016-05-04

    Topological insulators are a novel class of quantum matter with a gapped insulating bulk, yet gapless spin-helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe 2 thin film topological insulator devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity close to twice the conductance quantum at themore » double Dirac point, a series of ambipolar two-component half-integer Dirac quantum Hall states and an electron-hole total filling factor zero state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction, respectively. As a result, such a system paves the way to explore rich physics, ranging from topological magnetoelectric effects to exciton condensation.« less

  2. Lattice QCD at the physical point meets S U (2 ) chiral perturbation theory

    NASA Astrophysics Data System (ADS)

    Dürr, Stephan; Fodor, Zoltán; Hoelbling, Christian; Krieg, Stefan; Kurth, Thorsten; Lellouch, Laurent; Lippert, Thomas; Malak, Rehan; Métivet, Thibaut; Portelli, Antonin; Sastre, Alfonso; Szabó, Kálmán; Budapest-Marseille-Wuppertal Collaboration

    2014-12-01

    We perform a detailed, fully correlated study of the chiral behavior of the pion mass and decay constant, based on 2 +1 flavor lattice QCD simulations. These calculations are implemented using tree-level, O (a )-improved Wilson fermions, at four values of the lattice spacing down to 0.054 fm and all the way down to below the physical value of the pion mass. They allow a sharp comparison with the predictions of S U (2 ) chiral perturbation theory (χ PT ) and a determination of some of its low energy constants. In particular, we systematically explore the range of applicability of next-to-leading order (NLO) S U (2 ) χ PT in two different expansions: the first in quark mass (x expansion), and the second in pion mass (ξ expansion). We find that these expansions begin showing signs of failure for Mπ≳300 MeV , for the typical percent-level precision of our Nf=2 +1 lattice results. We further determine the LO low energy constants (LECs), F =88.0 ±1.3 ±0.2 and BMS ¯(2 GeV )=2.61 (6 )(1 ) GeV , and the related quark condensate, ΣMS ¯(2 GeV )=(272 ±4 ±1 MeV )3 , as well as the NLO ones, ℓ¯3=2.6 (5 )(3 ) and ℓ¯4=3.7 (4 )(2 ), with fully controlled uncertainties. We also explore the next-to-next-to-leading order (NNLO) expansions and the values of NNLO LECs. In addition, we show that the lattice results favor the presence of chiral logarithms. We further demonstrate how the absence of lattice results with pion masses below 200 MeV can lead to misleading results and conclusions. Our calculations allow a fully controlled, ab initio determination of the pion decay constant with a total 1% error, which is in excellent agreement with experiment.

  3. Baryon mass splittings and strong CP violation in SU(3) chiral perturbation theory

    DOE PAGES

    de Vries, Jordy; Mereghetti, Emanuele; Walker-Loud, Andre P.

    2015-10-08

    We study SU(3) flavor breaking corrections to the relation between the octet baryon masses and the nucleon-meson CP-violating interactions induced by the QCD theta term. We also work within the framework of SU(3) chiral perturbation theory and work through next-to-next-to-leading order in the SU(3) chiral expansion, which is O(m 2 q). At lowest order, the CP-odd couplings induced by the QCD θ - term are determined by mass splittings of the baryon octet, the classic result of Crewther et al. We show that for each isospin-invariant CP-violating nucleon-meson interaction there exists one relation which is respected by loop corrections upmore » to the order we work, while other leading-order relations are violated. With these relations we extract a precise value of the pion-nucleon coupling g - 0 by using recent lattice QCD evaluations of the proton-neutron mass splitting. Additionally, we derive semi-precise values for CP-violating coupling constants between heavier mesons and nucleons and discuss their phenomenological impact on electric dipole moments of nucleons and nuclei.« less

  4. Baryon mass splittings and strong CP violation in SU(3) chiral perturbation theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    de Vries, Jordy; Mereghetti, Emanuele; Walker-Loud, Andre P.

    We study SU(3) flavor breaking corrections to the relation between the octet baryon masses and the nucleon-meson CP-violating interactions induced by the QCD theta term. We also work within the framework of SU(3) chiral perturbation theory and work through next-to-next-to-leading order in the SU(3) chiral expansion, which is O(m 2 q). At lowest order, the CP-odd couplings induced by the QCD θ - term are determined by mass splittings of the baryon octet, the classic result of Crewther et al. We show that for each isospin-invariant CP-violating nucleon-meson interaction there exists one relation which is respected by loop corrections upmore » to the order we work, while other leading-order relations are violated. With these relations we extract a precise value of the pion-nucleon coupling g - 0 by using recent lattice QCD evaluations of the proton-neutron mass splitting. Additionally, we derive semi-precise values for CP-violating coupling constants between heavier mesons and nucleons and discuss their phenomenological impact on electric dipole moments of nucleons and nuclei.« less

  5. Study on the determination and chiral inversion of R-salbutamol in human plasma and urine by liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhou, Ting; Zeng, Jing; Liu, Shan; Zhao, Ting; Wu, Jie; Lai, Wenshi; He, Mingzhi; Xu, Beining; Qu, Shanshan; Xu, Ling; Tan, Wen

    2015-10-01

    The chiral inversion has been a concerned issue during the research and development of a chiral drug. In this study, a sensitive chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for determination of salbutamol enantiomers in human plasma and urine. The chiral inversion mechanism of R-salbutamol was fully investigated for the first time by studying the effects of physicochemical factors, including pH, temperature and time. A fitted model to predict the chiral inversion ratio of R-salbutamol was proposed using a Box-Behnken design. All the samples were separated on an Astec Chirobiotic T column and detected by a tandem mass spectrometer in multiple reaction monitoring mode. Lower limit of quantification of 0.100ng/mL was achieved under the optimized conditions. The method was fully validated and successfully applied to the clinical pharmacokinetic study of R-salbutamol in healthy volunteers. Chiral inversion of R-salbutamol to S-salbutamol has been detected in urine samples. The results indicated that pH and temperature were two dominant factors that caused the chiral inversion of R-salbutamol, which should be taken into consideration during the analysis of chiral drugs. The chiral inversion of R-salbutamol determined in this study was confirmed resulted from the gastric acid in stomach rather than caused by the analysis conditions. Moreover, the calculated results of the fitted model matched very well with the enantioselective pharmacokinetic study of R-salbutamol, and the individual difference of the chiral inversion ratio of R-salbutamol was related to the individual gastric environment. On the basis of the results, this study provides important and concrete information not only for the chiral analysis but also for the metabolism research of chiral drugs. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Strangeness and charmness content of the nucleon from overlap fermions on 2+1-flavor domain-wall fermion configurations

    NASA Astrophysics Data System (ADS)

    Gong, M.; Alexandru, A.; Chen, Y.; Doi, T.; Dong, S. J.; Draper, T.; Freeman, W.; Glatzmaier, M.; Li, A.; Liu, K. F.; Liu, Z.

    2013-07-01

    We present a calculation of the strangeness and charmness contents ⟨N|s¯s|N⟩ and ⟨N|c¯c|N⟩ of the nucleon from dynamical lattice QCD with 2+1 flavors. The calculation is performed with overlap valence quarks on 2+1-flavor domain-wall fermion gauge configurations. The configurations are generated by the RBC collaboration on a 243×64 lattice with sea-quark mass aml=0.005, ams=0.04, and inverse lattice spacing a-1=1.73GeV. Both actions have chiral symmetry which is essential in avoiding contamination due to the operator mixing with other flavors. The nucleon propagator and the quark loops are both computed with stochastic grid sources, while low-mode substitution and low-mode averaging methods are used respectively which substantially improve the signal-to-noise ratio. We obtain the strangeness matrix element fTs=ms⟨N|s¯s|N⟩/MN=0.0334(62), and the charmness content fTc=mc⟨N|c¯c|N⟩/MN=0.094(31) which is resolved from zero by 3σ precision for the first time.

  7. Evidence for magnetic Weyl fermions in a correlated metal

    NASA Astrophysics Data System (ADS)

    Kuroda, K.; Tomita, T.; Suzuki, M.-T.; Bareille, C.; Nugroho, A. A.; Goswami, P.; Ochi, M.; Ikhlas, M.; Nakayama, M.; Akebi, S.; Noguchi, R.; Ishii, R.; Inami, N.; Ono, K.; Kumigashira, H.; Varykhalov, A.; Muro, T.; Koretsune, T.; Arita, R.; Shin, S.; Kondo, Takeshi; Nakatsuji, S.

    2017-11-01

    Weyl fermions have been observed as three-dimensional, gapless topological excitations in weakly correlated, inversion-symmetry-breaking semimetals. However, their realization in spontaneously time-reversal-symmetry-breaking phases of strongly correlated materials has so far remained hypothetical. Here, we report experimental evidence for magnetic Weyl fermions in Mn3Sn, a non-collinear antiferromagnet that exhibits a large anomalous Hall effect, even at room temperature. Detailed comparison between angle-resolved photoemission spectroscopy (ARPES) measurements and density functional theory (DFT) calculations reveals significant bandwidth renormalization and damping effects due to the strong correlation among Mn 3d electrons. Magnetotransport measurements provide strong evidence for the chiral anomaly of Weyl fermions--namely, the emergence of positive magnetoconductance only in the presence of parallel electric and magnetic fields. Since weak magnetic fields (approximately 10 mT) are adequate to control the distribution of Weyl points and the large fictitious fields (equivalent to approximately a few hundred T) produced by them in momentum space, our discovery lays the foundation for a new field of science and technology involving the magnetic Weyl excitations of strongly correlated electron systems such as Mn3Sn.

  8. Chiral drug analysis using mass spectrometric detection relevant to research and practice in clinical and forensic toxicology.

    PubMed

    Schwaninger, Andrea E; Meyer, Markus R; Maurer, Hans H

    2012-12-21

    This paper reviews analytical approaches published in 2002-2012 for chiral drug analysis and their relevance in research and practice in the field of clinical and forensic toxicology. Separation systems such as gas chromatography, high performance liquid chromatography, capillary electromigration, and supercritical fluid chromatography, all coupled to mass spectrometry, are discussed. Typical applications are reviewed for relevant chiral analytes such as amphetamines and amphetamine-derived designer drugs, methadone, tramadol, psychotropic and other CNS acting drugs, anticoagulants, cardiovascular drugs, and some other drugs. Usefulness of chiral drug analysis in the interpretation of analytical results in clinical and forensic toxicology is discussed as well. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Perturbative renormalization factors and O(a{sup 2}) corrections for lattice four-fermion operators with improved fermion/gluon actions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Constantinou, Martha; Panagopoulos, Haralambos; Skouroupathis, Apostolos

    2011-04-01

    In this work we calculate the corrections to the amputated Green's functions of four-fermion operators, in 1-loop lattice perturbation theory. One of the novel aspects of our calculations is that they are carried out to second order in the lattice spacing, O(a{sup 2}). We employ the Wilson/clover action for massless fermions (also applicable for the twisted mass action in the chiral limit) and a family of Symanzik improved actions for gluons. Our calculations have been carried out in a general covariant gauge. Results have been obtained for several popular choices of values for the Symanzik coefficients (Plaquette, Tree-level Symanzik, Iwasaki,more » TILW and DBW2 action). While our Green's function calculations regard any pointlike four-fermion operators which do not mix with lower dimension ones, we pay particular attention to {Delta}F=2 operators, both parity conserving and parity violating (F stands for flavor: S, C, B). By appropriately projecting those bare Green's functions we compute the perturbative renormalization constants for a complete basis of four-fermion operators and we study their mixing pattern. For some of the actions considered here, even O(a{sup 0}) results did not exist in the literature to date. The correction terms which we calculate (along with our previous O(a{sup 2}) calculation of Z{sub {Psi}}[M. Constantinou, V. Lubicz, H. Panagopoulos, and F. Stylianou, J. High Energy Phys. 10 (2009) 064.][M. Constantinou, P. Dimopoulos, R. Frezzotti, G. Herdoiza, K. Jansen, V. Lubicz, H. Panagopoulos, G. C. Rossi, S. Simula, F. Stylianou, and A. Vladikas, J. High Energy Phys. 08 (2010) 068.][C. Alexandrou, M. Constantinou, T. Korzec, H. Panagopoulos, and F. Stylianou (unpublished).]) are essential ingredients for minimizing the lattice artifacts which are present in nonperturbative evaluations of renormalization constants with the RI{sup '}-MOM method. Our perturbative results, for the matrix elements of {Delta}F=2 operators and for the

  10. Direct mass limits for chiral fourth-generation quarks in all mixing scenarios.

    PubMed

    Flacco, Christian J; Whiteson, Daniel; Tait, Tim M P; Bar-Shalom, Shaouly

    2010-09-10

    Present limits on chiral fourth-generation quark masses mb' and mt' are broadly generalized and strengthened by combining both t' and b' decays and considering a full range of t' and b' flavor-mixing scenarios with the lighter generations (to 1-‖V44‖2≈10(-13)). Various characteristic mass-splitting choices are considered. With mt'>mb' we find that CDF Collaboration limits on the b' mass vary by no more than 10%-20% with any choice of flavor mixing, while for the t' mass, we typically find stronger bounds, in some cases up to mt'>430  GeV. For mb'>mt', we find mb'>380-430  GeV, depending on the flavor mixing and the size of the mt'-mb' mass splitting.

  11. Topological charge and the spectrum of exactly massless fermions on the lattice

    NASA Astrophysics Data System (ADS)

    Chiu, Ting-Wai

    1998-10-01

    The square root of the positive definite Hermitian operator D†wDw in Neuberger's proposal of exactly massless quarks on the lattice is implemented by the recursion formula Yk+1=12(Yk+D†wDwY-1k) with Y0=1, where Y2k converges to D†wDw quadratically. The spectrum of the lattice Dirac operator for single massless fermion in two dimensional background U(1) gauge fields is investigated. For smooth background gauge fields with nonzero topological charge, the exact zero modes with definite chirality are reproduced to a very high precision on a finite lattice and the index theorem is satisfied exactly. The fermionic determinants are also computed and they are in good agreement with the continuum exact solution.

  12. Chiral U(1) flavor models and flavored Higgs doublets: the top FB asymmetry and the W jj

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ko, P.; Omura, Yuji; Yu, Chaehyun

    2012-01-01

    We present U(1) flavor models for leptophobic Z' with flavor dependent couplings to the right-handed up-type quarks in the Standard Model (SM), which can accommodate the recent data on the top forward-backward (FB) asymmetry and the dijet resonance associated with a W boson reported by CDF Collaboration. Such flavor-dependent leptophobic charge assignments generally require extra chiral fermions for anomaly cancellation. Also the chiral nature of U(1)' flavor symmetry calls for new U(1)'-charged Higgs doublets in order for the SM fermions to have realistic renormalizable Yukawa couplings. The stringent constraints from the top FB asymmetry at the Tevatron and the samemore » sign top pair production at the LHC can be evaded due to contributions of the extra Higgs doublets. We also show that the extension could realize cold dark matter candidates.« less

  13. Self-similar inverse cascade of magnetic helicity driven by the chiral anomaly

    DOE PAGES

    Hirono, Yuji; Kharzeev, Dmitri E.; Yin, Yi

    2015-12-28

    For systems with charged chiral fermions, the imbalance of chirality in the presence of magnetic field generates an electric current—this is the chiral magnetic effect (CME). We study the dynamical real-time evolution of electromagnetic fields coupled by the anomaly to the chiral charge density and the CME current by solving the Maxwell-Chern-Simons equations. We find that the CME induces the inverse cascade of magnetic helicity toward the large distances, and that at late times this cascade becomes self-similar, with universal exponents. We also find that in terms of gauge field topology the inverse cascade represents the transition from linked electricmore » and magnetic fields (Hopfions) to the knotted configuration of magnetic field (Chandrasekhar-Kendall states). The magnetic reconnections are accompanied by the pulses of the CME current directed along the magnetic field lines. In conclusion, we devise an experimental signature of these phenomena in heavy ion collisions, and speculate about implications for condensed matter systems.« less

  14. Fermionic dark matter and neutrino masses in a B - L model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sánchez-Vega, B. L.; Schmitz, E. R.

    2015-09-01

    In this work we present a common framework for neutrino masses and dark matter. Specifically, we work with a local B - L extension of the standard model which has three right-handed neutrinos, n(Ri), and some extra scalars, Phi, phi(i), besides the standard model fields. The n(Ri)'s have nonstandard B - L quantum numbers and thus these couple to different scalars. This model has the attractive property that an almost automatic Z(2) symmetry acting only on a fermionic field, n(R3), is present. Taking advantage of this Z(2) symmetry, we study both the neutrino mass generation via a natural seesaw mechanismmore » at low energy and the possibility of n(R3) being a dark matter candidate. For this last purpose, we study its relic abundance and its compatibility with the current direct detection experiments.« less

  15. Stable Pentaquarks from Strange Chiral Multiplets

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Silas Beane

    2004-12-01

    The assumption of strong diquark correlations in the QCD spectrum suggests flavor multiplets of hadrons that are degenerate in the chiral limit. Generally it would be unnatural for there to be degeneracy in the hadron spectrum that is not protected by a QCD symmetry. Here we show--for pentaquarks constructed from diquarks--that these degeneracies can be naturally protected by the full chiral symmetry of QCD. The resulting chiral multiplet structure recovers the ideally-mixed pentaquark mass spectrum of the diquark model, and interestingly, requires that the axial couplings of the pentaquarks to states outside the degenerate multiplets vanish in the chiral limit.more » This result suggests that if these hadrons exist, they are stable in the chiral limit and therefore have widths that scale as the fourth power of the kaon mass over the chiral symmetry breaking scale. Natural-size widths are of order a few MeV.« less

  16. 3D Polarized Imaging of Coronal Mass Ejections: Chirality of a CME

    NASA Astrophysics Data System (ADS)

    DeForest, C. E.; de Koning, C. A.; Elliott, H. A.

    2017-12-01

    We report on a direct polarimetric determination of the chirality of a coronal mass ejection (CME), using the physics of Thomson scattering applied to synoptic polarized images from the Solar Terrestrial Relations Observatories/COR2 coronagraph. We confirmed the determination using in situ magnetic field measurements of the same CME with the ACE spacecraft. CME chirality is related to the helicity ejected from the solar corona along with the mass and field entrained in the CME. It is also important to prediction of the space-weather-relevant Z component of the CME magnetic field. Hence, remote measurement of CME chirality is an important step toward both understanding CME physics and predicting geoeffectiveness of individual CMEs. The polarimetric properties of Thomson scattering are well known and can, in principle, be used to measure the 3D structure of imaged objects in the solar corona and inner heliosphere. However, reduction of that principle to practice has been limited by the twin difficulties of background subtraction and the signal-to-noise ratio in coronagraph data. Useful measurements of the 3D structure require relative photometry at a few percent precision level in each linear polarization component of the K corona. This corresponds to a relative photometric precision of order 10-4 in direct images of the sky before subtraction of the F corona and related signal. Our measurement was enabled by recent developments in signal processing, which enable a better separation of the photometric signal from noise in the synoptic COR2 data. We discuss the relevance of this demonstration measurement to future instrument requirements, and to the future measurements of 3D structures in CMEs and other solar wind features.

  17. Symmetries and mass splittings QCD 2 coupled to adjoint fermions

    NASA Astrophysics Data System (ADS)

    Boorstein, Joshua; Kutasov, David

    1994-06-01

    Two-dimensional QCD coupled to fermions in the adjoint representation of the gauge group SU( N), a useful toy model of QCD strings, is supersymmetric for a certain ratio of quark mass and gauge coupling constant. Here we study the theory in the vicinity of the supersymmetric point; in particular we exhibit the algebraic structure of the model and show that the mass splittings as one moves away from the supersymmetric point obey a universal relation of the form Mi2(B)- Mi2(F) = Miδm + O( δm3). We discuss the connection of this relation to string and quark model expectations and verify it numerically for large N. At least for low lying states the O( δm3) corrections are extremely small. We also discuss a natural generalization of QCD 2 with an infinite number of couplings, which preserves SUSY. This leads to a Landau-Ginzburg description of the theory, and may be useful for defining a scaling limit in which smooth worldsheets appear.

  18. Staggered chiral perturbation theory in the two-flavor case

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Du Xining

    2010-07-01

    I study two-flavor staggered chiral perturbation theory in the light pseudoscalar sector. The pion mass and decay constant are calculated through next-to-leading order in the partially-quenched case. In the limit where the strange quark mass is large compared to the light quark masses and the taste splittings, I show that the SU(2) staggered chiral theory emerges from the SU(3) staggered chiral theory, as expected. Explicit relations between SU(2) and SU(3) low energy constants and taste-violating parameters are given. The results are useful for SU(2) chiral fits to asqtad data and allow one to incorporate effects from varying strange quark masses.

  19. Orbital angular momentum and spectral flow in two-dimensional chiral superfluids.

    PubMed

    Tada, Yasuhiro; Nie, Wenxing; Oshikawa, Masaki

    2015-05-15

    We study the orbital angular momentum (OAM) L_{z} in two-dimensional chiral (p_{x}+ip_{y})^{ν}-wave superfluids (SFs) of N fermions on a disk at zero temperature, in terms of spectral asymmetry and spectral flow. It is shown that L_{z}=νN/2 for any integer ν, in the Bose-Einstein condensation regime. In contrast, in the BCS limit, while the OAM is L_{z}=N/2 for the p+ip-wave SF, for chiral SFs with ν≥2, the OAM is remarkably suppressed as L_{z}=N×O(Δ_{0}/ϵ_{F})≪N, where Δ_{0} is the gap amplitude and ϵ_{F} is the Fermi energy. We demonstrate that the difference between the p+ip-wave SF and the other chiral SFs in the BCS regimes originates from the nature of edge modes and related depairing effects.

  20. Exact results for the star lattice chiral spin liquid

    NASA Astrophysics Data System (ADS)

    Kells, G.; Mehta, D.; Slingerland, J. K.; Vala, J.

    2010-03-01

    We examine the star lattice Kitaev model whose ground state is a chiral spin liquid. We fermionize the model such that the fermionic vacua are toric-code states on an effective Kagome lattice. This implies that the Abelian phase of the system is inherited from the fermionic vacua and that time-reversal symmetry is spontaneously broken at the level of the vacuum. In terms of these fermions we derive the Bloch-matrix Hamiltonians for the vortex-free sector and its time-reversed counterpart and illuminate the relationships between the sectors. The phase diagram for the model is shown to be a sphere in the space of coupling parameters around the triangles of the lattices. The Abelian phase lies inside the sphere and the critical boundary between topologically distinct Abelian and non-Abelian phases lies on the surface. Outside the sphere the system is generically gapped except in the planes where the coupling parameters between the vertices on triangles are zero. These cases correspond to bipartite lattice structures and the dispersion relations are similar to that of the original Kitaev honeycomb model. In a further analysis we demonstrate the threefold non-Abelian ground-state degeneracy on a torus by explicit calculation.

  1. Exotic topological density waves in cold atomic Rydberg-dressed fermions

    PubMed Central

    Li, Xiaopeng; Sarma, S Das

    2015-01-01

    Versatile controllability of interactions in ultracold atomic and molecular gases has now reached an era where quantum correlations and unconventional many-body phases can be studied with no corresponding analogues in solid-state systems. Recent experiments in Rydberg atomic gases have achieved exquisite control over non-local interactions, allowing novel quantum phases unreachable with the usual local interactions in atomic systems. Here we study Rydberg-dressed atomic fermions in a three-dimensional optical lattice predicting the existence of hitherto unheard-of exotic mixed topological density wave phases. By varying the spatial range of the non-local interaction, we find various chiral density waves with spontaneous time-reversal symmetry breaking, whose quasiparticles form three-dimensional quantum Hall and Weyl semimetal states. Remarkably, certain density waves even exhibit mixed topologies beyond the existing topological classification. Our results suggest gapless fermionic states could exhibit far richer topology than previously expected. PMID:25972134

  2. On the search for the chiral anomaly in Weyl semimetals: the negative longitudinal magnetoresistance

    NASA Astrophysics Data System (ADS)

    dos Reis, R. D.; Ajeesh, M. O.; Kumar, N.; Arnold, F.; Shekhar, C.; Naumann, M.; Schmidt, M.; Nicklas, M.; Hassinger, E.

    2016-08-01

    Recently, the existence of massless chiral (Weyl) fermions has been postulated in a class of semi-metals with a non-trivial energy dispersion. These materials are now commonly dubbed Weyl semi-metals (WSM). One predicted property of Weyl fermions is the chiral or Adler-Bell-Jackiw anomaly, a chirality imbalance in the presence of parallel magnetic and electric fields. In WSM, it is expected to induce a negative longitudinal magnetoresistance (MR). Here, we present experimental evidence that the observation of the chiral anomaly can be hindered by an effect called ‘current jetting’. This effect also leads to a strong apparent negative longitudinal MR, but it is characterized by a highly non-uniform current distribution inside the sample. It appears in materials possessing a large field-induced anisotropy of the resistivity tensor, such as almost compensated high-mobility semimetals due to the orbital effect. In case of a non-homogeneous current injection, the potential distribution is strongly distorted in the sample. As a consequence, an experimentally measured potential difference is not proportional to the intrinsic resistance. Our results on the MR of the Weyl semimetal candidate materials NbP, NbAs, TaAs, and TaP exhibit distinct signatures of an inhomogeneous current distribution, such as a field-induced ‘zero resistance’ and a strong dependence of the ‘measured resistance’ on the position, shape, and type of the voltage and current contacts on the sample. A misalignment between the current and the magnetic-field directions can even induce a ‘negative resistance’. Finite-element simulations of the potential distribution inside the sample, using typical resistance anisotropies, are in good agreement with the experimental findings. Our study demonstrates that great care must be taken before interpreting measurements of a negative longitudinal MR as evidence for the chiral anomaly in putative Weyl semimetals.

  3. Bosonization of fermions coupled to topologically massive gravity

    NASA Astrophysics Data System (ADS)

    Fradkin, Eduardo; Moreno, Enrique F.; Schaposnik, Fidel A.

    2014-03-01

    We establish a duality between massive fermions coupled to topologically massive gravity (TMG) in d=3 space-time dimensions and a purely gravity theory which also will turn out to be a TMG theory but with different parameters: the original graviton mass in the TMG theory coupled to fermions picks up a contribution from fermion bosonization. We obtain explicit bosonization rules for the fermionic currents and for the energy-momentum tensor showing that the identifications do not depend explicitly on the parameters of the theory. These results are the gravitational analog of the results for 2+1 Abelian and non-Abelian bosonization in flat space-time.

  4. Fermion hierarchy from sfermion anarchy

    DOE PAGES

    Altmannshofer, Wolfgang; Frugiuele, Claudia; Harnik, Roni

    2014-12-31

    We present a framework to generate the hierarchical flavor structure of Standard Model quarks and leptons from loops of superpartners. The simplest model consists of the minimal supersymmetric standard model with tree level Yukawa couplings for the third generation only and anarchic squark and slepton mass matrices. Agreement with constraints from low energy flavor observables, in particular Kaon mixing, is obtained for supersymmetric particles with masses at the PeV scale or above. In our framework both the second and the first generation fermion masses are generated at 1-loop. Despite this, a novel mechanism generates a hierarchy among the first andmore » second generations without imposing a symmetry or small parameters. A second-to-first generation mass ratio of order 100 is typical. The minimal supersymmetric standard model thus includes all the necessary ingredients to realize a fermion spectrum that is qualitatively similar to observation, with hierarchical masses and mixing. The minimal framework produces only a few quantitative discrepancies with observation, most notably the muon mass is too low. Furthermore, we discuss simple modifications which resolve this and also investigate the compatibility of our model with gauge and Yukawa coupling Unification.« less

  5. Fermion masses and mixings and dark matter constraints in a model with radiative seesaw mechanism

    NASA Astrophysics Data System (ADS)

    Bernal, Nicolás; Cárcamo Hernández, A. E.; de Medeiros Varzielas, Ivo; Kovalenko, Sergey

    2018-05-01

    We formulate a predictive model of fermion masses and mixings based on a Δ(27) family symmetry. In the quark sector the model leads to the viable mixing inspired texture where the Cabibbo angle comes from the down quark sector and the other angles come from both up and down quark sectors. In the lepton sector the model generates a predictive structure for charged leptons and, after radiative seesaw, an effective neutrino mass matrix with only one real and one complex parameter. We carry out a detailed analysis of the predictions in the lepton sector, where the model is only viable for inverted neutrino mass hierarchy, predicting a strict correlation between θ 23 and θ 13. We show a benchmark point that leads to the best-fit values of θ 12, θ 13, predicting a specific sin2 θ 23 ≃ 0.51 (within the 3 σ range), a leptonic CP-violating Dirac phase δ ≃ 281.6° and for neutrinoless double-beta decay m ee ≃ 41.3 meV. We turn then to an analysis of the dark matter candidates in the model, which are stabilized by an unbroken ℤ2 symmetry. We discuss the possibility of scalar dark matter, which can generate the observed abundance through the Higgs portal by the standard WIMP mechanism. An interesting possibility arises if the lightest heavy Majorana neutrino is the lightest ℤ2-odd particle. The model can produce a viable fermionic dark matter candidate, but only as a feebly interacting massive particle (FIMP), with the smallness of the coupling to the visible sector protected by a symmetry and directly related to the smallness of the light neutrino masses.

  6. A search for excited fermions in electron-proton collisions at HERA

    NASA Astrophysics Data System (ADS)

    Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Repond, J.; Schlereth, J.; Stanek, R.; Talaga, R. L.; Thron, J.; Arzarello, F.; Ayad, R.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Romeo, G. Cara; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; D'Auria, S.; Frasconi, F.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Polini, A.; Sartorelli, G.; Timellini, R.; Garcia, Y. Zamora; Zichichi, A.; Bargende, A.; Crittenden, J.; Desch, K.; Diekmann, B.; Doeker, T.; Eckart, M.; Feld, L.; Frey, A.; Geerts, M.; Geitz, G.; Grothe, M.; Hartmann, H.; Haun, D.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mari, S. M.; Mass, A.; Mengel, S.; Mollen, J.; Paul, E.; Rembser, Ch.; Schattevoy, R.; Schneider, J.-L.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Dyce, N.; Foster, B.; George, S.; Gilmore, R.; Heath, G. P.; Heath, H. F.; Llewellyn, T. J.; Morgado, C. J. S.; Norman, D. J. P.; O'Mara, J. A.; Tapper, R. J.; Wilson, S. S.; Yoshida, R.; Rau, R. R.; Arneodo, M.; Iannotti, L.; Schioppa, M.; Susinno, G.; Bernstein, A.; Caldwell, A.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Eskreys, K.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Rulikowska-Zarebska, E.; Suszycki, L.; Zajac, J.; Kedzierski, T.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Böttcher, S.; Coldewey, C.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Göttlicher, P.; Gutjahr, B.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Hultschig, H.; Iga, Y.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Köpke, L.; Kötz, U.; Kowalski, H.; Kroger, W.; Krüger, J.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mańczak, O.; Ng, J. S. T.; Nickel, S.; Notz, D.; Ohrenberg, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Stiliaris, E.; Voß, T.; Westphal, D.; Wolf, G.; Youngman, C.; Grabosch, H. J.; Leich, A.; Meyer, A.; Rethfeldt, C.; Schlenstedt, S.; Barbagli, G.; Pelfer, P.; Anzivino, G.; Maccarrone, G.; de Pasquale, S.; Qian, S.; Votano, L.; Bamberger, A.; Freidhof, A.; Poser, T.; Söldner-Rembold, S.; Schroeder, J.; Theisen, G.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Fleck, I.; Jamieson, V. A.; Saxon, D. H.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Kammerlocher, H.; Krebs, B.; Neumann, T.; Sinkus, R.; Wick, K.; Badura, E.; Burow, B. D.; Fürtjes, A.; Hagge, L.; Lohrmann, E.; Mainusch, J.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Schott, W.; Terron, J.; Zetsche, F.; Bacon, T. C.; Beuselinck, R.; Butterworth, I.; Gallo, E.; Harris, V. L.; Hung, B. H.; Long, K. R.; Miller, D. B.; Morawitz, P. P. O.; Prinias, A.; Sedgbeer, J. K.; Whitfield, A. F.; Mallik, U.; McCliment, E.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Zhang, Y.; Cloth, P.; Filges, D.; An, S. H.; Hong, S. M.; Nam, S. W.; Park, S. K.; Suh, M. H.; Yon, S. H.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Cases, G.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Del Peso, J.; Puga, J.; de Trocóniz, J. F.; Ikraiam, F.; Mayer, J. K.; Smith, G. R.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; St. Laurent, M.; Ullmann, R.; Zacek, G.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Y. A.; Kobrin, V. D.; Kuzmin, V. A.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Bentvelsen, S.; Botje, M.; Chlebana, F.; Dake, A.; Engelen, J.; de Jong, P.; de Kamps, M.; Kooijman, P.; Kruse, A.; O'Dell, V.; Tenner, A.; Tiecke, H.; Verkerke, W.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Honscheid, K.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, I. H.; Romanowski, T. A.; Seidlein, R.; Bailey, D. S.; Blair, G. A.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Daniels, D.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Luffman, P. E.; Lindemann, L.; McFall, J.; Nath, C.; Quadt, A.; Uijterwaal, H.; Walczak, R.; Wilson, F. F.; Yip, T.; Abbiendi, G.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; de Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Butterworth, J. M.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Iori, M.; Marini, G.; Mattioli, M.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Prytz, K.; Shah, T. P.; Short, T. L.; Barberis, E.; Cartiglia, N.; Dubbs, T.; Heusch, C.; van Hook, M.; Hubbard, B.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Biltzinger, J.; Seifert, R. J.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kuze, M.; Mine, S.; Nagasawa, Y.; Nagira, T.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Nagayama, S.; Nakamitsu, Y.; Cirio, R.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Brkic, M.; Crombie, M. B.; Gingrich, D. M.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Sampson, C. R.; Teuscher, R. J.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Blankenship, K.; Kochocki, J.; Lu, B.; Mo, L. W.; Bogusz, W.; Charchula, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprazak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Eisenberg, Y.; Glasman, C.; Karshon, U.; Revel, D.; Shapira, A.; Ali, I.; Behrens, B.; Dasu, S.; Fordham, C.; Foudas, C.; Goussiou, A.; Loveless, R. J.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Tsurugai, T.; Bhadra, S.; Frisken, W. R.; Furutani, K. M.

    1995-12-01

    A search for excited states of the standard model fermions was performed using the ZEUS detector at the HERA electron-proton collider, operating at a centre of mass energy of 296 GeV. In a sample corresponding to an integrated luminosity of 0.55 pb-1, no evidence was found for any resonant state decaying into final states composed of a fermion and a gauge boson. Limits on the coupling strength times branching ratio of excited fermions are presented for masses between 50 GeV and 250 GeV, extending previous search regions significantly.

  7. Klein tunneling and electron optics in Dirac-Weyl fermion systems with tilted energy dispersion

    NASA Astrophysics Data System (ADS)

    Nguyen, V. Hung; Charlier, J.-C.

    2018-06-01

    The transport properties of relativisticlike fermions have been extensively studied in solid-state systems with isotropic energy dispersions. Recently, several two-dimensional and three-dimensional Dirac-Weyl (DW) materials exhibiting tilted energy dispersions around their DW cones have been explored. Here, we demonstrate that such a tilt character could induce drastically different transport phenomena, compared to the isotropic-dispersion cases. Indeed, the Klein tunneling of DW fermions of opposite chiralities is predicted to appear along two separated oblique directions. In addition, valley filtering and beam splitting effects are easily tailored by dopant engineering techniques whereas the refraction of electron waves at a (p -n )-doped interface is dramatically modified by the tilt, thus paving the way for emerging applications in electron optics and valleytronics.

  8. Model of chiral spin liquids with Abelian and non-Abelian topological phases

    DOE PAGES

    Chen, Jyong-Hao; Mudry, Christopher; Chamon, Claudio; ...

    2017-12-15

    In this article, we present a two-dimensional lattice model for quantum spin-1/2 for which the low-energy limit is governed by four flavors of strongly interacting Majorana fermions. We study this low-energy effective theory using two alternative approaches. The first consists of a mean-field approximation. The second consists of a random phase approximation (RPA) for the single-particle Green's functions of the Majorana fermions built from their exact forms in a certain one-dimensional limit. The resulting phase diagram consists of two competing chiral phases, one with Abelian and the other with non-Abelian topological order, separated by a continuous phase transition. Remarkably, themore » Majorana fermions propagate in the two-dimensional bulk, as in the Kitaev model for a spin liquid on the honeycomb lattice. We identify the vison fields, which are mobile (they are static in the Kitaev model) domain walls propagating along only one of the two space directions.« less

  9. Model of chiral spin liquids with Abelian and non-Abelian topological phases

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Jyong-Hao; Mudry, Christopher; Chamon, Claudio

    In this article, we present a two-dimensional lattice model for quantum spin-1/2 for which the low-energy limit is governed by four flavors of strongly interacting Majorana fermions. We study this low-energy effective theory using two alternative approaches. The first consists of a mean-field approximation. The second consists of a random phase approximation (RPA) for the single-particle Green's functions of the Majorana fermions built from their exact forms in a certain one-dimensional limit. The resulting phase diagram consists of two competing chiral phases, one with Abelian and the other with non-Abelian topological order, separated by a continuous phase transition. Remarkably, themore » Majorana fermions propagate in the two-dimensional bulk, as in the Kitaev model for a spin liquid on the honeycomb lattice. We identify the vison fields, which are mobile (they are static in the Kitaev model) domain walls propagating along only one of the two space directions.« less

  10. Model of chiral spin liquids with Abelian and non-Abelian topological phases

    NASA Astrophysics Data System (ADS)

    Chen, Jyong-Hao; Mudry, Christopher; Chamon, Claudio; Tsvelik, A. M.

    2017-12-01

    We present a two-dimensional lattice model for quantum spin-1/2 for which the low-energy limit is governed by four flavors of strongly interacting Majorana fermions. We study this low-energy effective theory using two alternative approaches. The first consists of a mean-field approximation. The second consists of a random phase approximation (RPA) for the single-particle Green's functions of the Majorana fermions built from their exact forms in a certain one-dimensional limit. The resulting phase diagram consists of two competing chiral phases, one with Abelian and the other with non-Abelian topological order, separated by a continuous phase transition. Remarkably, the Majorana fermions propagate in the two-dimensional bulk, as in the Kitaev model for a spin liquid on the honeycomb lattice. We identify the vison fields, which are mobile (they are static in the Kitaev model) domain walls propagating along only one of the two space directions.

  11. Non-Abelian S =1 chiral spin liquid on the kagome lattice

    NASA Astrophysics Data System (ADS)

    Liu, Zheng-Xin; Tu, Hong-Hao; Wu, Ying-Hai; He, Rong-Qiang; Liu, Xiong-Jun; Zhou, Yi; Ng, Tai-Kai

    2018-05-01

    We study S =1 spin liquid states on the kagome lattice constructed by Gutzwiller-projected px+i py superconductors. We show that the obtained spin liquids are either non-Abelian or Abelian topological phases, depending on the topology of the fermionic mean-field state. By calculating the modular matrices S and T , we confirm that projected topological superconductors are non-Abelian chiral spin liquid (NACSL). The chiral central charge and the spin Hall conductance we obtained agree very well with the S O (3) 1 (or, equivalently, S U (2) 2 ) field-theory predictions. We propose a local Hamiltonian which may stabilize the NACSL. From a variational study, we observe a topological phase transition from the NACSL to the Z2 Abelian spin liquid.

  12. Symmetry Transition Preserving Chirality in QCD: A Versatile Random Matrix Model

    NASA Astrophysics Data System (ADS)

    Kanazawa, Takuya; Kieburg, Mario

    2018-06-01

    We consider a random matrix model which interpolates between the chiral Gaussian unitary ensemble and the Gaussian unitary ensemble while preserving chiral symmetry. This ensemble describes flavor symmetry breaking for staggered fermions in 3D QCD as well as in 4D QCD at high temperature or in 3D QCD at a finite isospin chemical potential. Our model is an Osborn-type two-matrix model which is equivalent to the elliptic ensemble but we consider the singular value statistics rather than the complex eigenvalue statistics. We report on exact results for the partition function and the microscopic level density of the Dirac operator in the ɛ regime of QCD. We compare these analytical results with Monte Carlo simulations of the matrix model.

  13. Chiral corrections to the Adler-Weisberger sum rule

    NASA Astrophysics Data System (ADS)

    Beane, Silas R.; Klco, Natalie

    2016-12-01

    The Adler-Weisberger sum rule for the nucleon axial-vector charge, gA , offers a unique signature of chiral symmetry and its breaking in QCD. Its derivation relies on both algebraic aspects of chiral symmetry, which guarantee the convergence of the sum rule, and dynamical aspects of chiral symmetry breaking—as exploited using chiral perturbation theory—which allow the rigorous inclusion of explicit chiral symmetry breaking effects due to light-quark masses. The original derivations obtained the sum rule in the chiral limit and, without the benefit of chiral perturbation theory, made various attempts at extrapolating to nonvanishing pion masses. In this paper, the leading, universal, chiral corrections to the chiral-limit sum rule are obtained. Using PDG data, a recent parametrization of the pion-nucleon total cross sections in the resonance region given by the SAID group, as well as recent Roy-Steiner equation determinations of subthreshold amplitudes, threshold parameters, and correlated low-energy constants, the Adler-Weisberger sum rule is confronted with experimental data. With uncertainty estimates associated with the cross-section parametrization, the Goldberger-Treimann discrepancy, and the truncation of the sum rule at O (Mπ4) in the chiral expansion, this work finds gA=1.248 ±0.010 ±0.007 ±0.013 .

  14. Chiral Luttinger liquids and a generalized Luttinger's theorem in fractional quantum Hall edges via finite-entanglement scaling

    NASA Astrophysics Data System (ADS)

    Varjas, Daniel; Zaletel, Michael; Moore, Joel

    2014-03-01

    We use bosonic field theories and the infinite system density matrix renormalization group (iDMRG) method to study infinite strips of fractional quantum Hall (FQH) states starting from microscopic Hamiltonians. Finite-entanglement scaling allows us to accurately measure chiral central charge, edge mode exponents and momenta without finite-size errors. We analyze states in the first and second level of the standard hierarchy and compare our results to predictions of the chiral Luttinger liquid (χLL) theory. The results confirm the universality of scaling exponents in chiral edges and demonstrate that renormalization is subject to universal relations in the non-chiral case. We prove a generalized Luttinger's theorem involving all singularities in the momentum-resolved density, which naturally arises when mapping Landau levels on a cylinder to a fermion chain and deepens our understanding of non-Fermi liquids in 1D.

  15. Magnetic Properties of Heavy Fermion Compound Ce5Si4 with Chiral Structure

    NASA Astrophysics Data System (ADS)

    Sato, Yoshiki J.; Shimizu, Yusei; Nakamura, Ai; Homma, Yoshiya; Li, Dexin; Maurya, Arvind; Honda, Fuminori; Aoki, Dai

    2018-07-01

    The low-temperature magnetic properties of Ce5Si4 with a chiral structure have been studied by electrical resistivity, heat capacity, and magnetization measurements using single-crystalline samples. It is found that Ce5Si4 is an antiferromagnet with moderately correlated electronic states. The resistivity decreases strongly under magnetic fields, indicating scaling behavior based on the Coqblin-Schrieffer model. The obtained characteristic energy scale of the Kondo effect is clearly anisotropic for the magnetic field H ∥ a-axis and H ∥ c-axis in the tetragonal structure, possibly related to the anisotropic antiferromagnetic phase. Furthermore, in the antiferromagnetic phase, a shoulderlike crossover anomaly is observed in C/T. A possible scenario is that non-ordered Ce atoms exist even below TN in this chiral system.

  16. Bold Diagrammatic Monte Carlo for Fermionic and Fermionized Systems

    NASA Astrophysics Data System (ADS)

    Svistunov, Boris

    2013-03-01

    In three different fermionic cases--repulsive Hubbard model, resonant fermions, and fermionized spins-1/2 (on triangular lattice)--we observe the phenomenon of sign blessing: Feynman diagrammatic series features finite convergence radius despite factorial growth of the number of diagrams with diagram order. Bold diagrammatic Monte Carlo technique allows us to sample millions of skeleton Feynman diagrams. With the universal fermionization trick we can fermionize essentially any (bosonic, spin, mixed, etc.) lattice system. The combination of fermionization and Bold diagrammatic Monte Carlo yields a universal first-principle approach to strongly correlated lattice systems, provided the sign blessing is a generic fermionic phenomenon. Supported by NSF and DARPA

  17. Fermion number of twisted kinks in the NJL2 model revisited

    NASA Astrophysics Data System (ADS)

    Thies, Michael

    2018-03-01

    As a consequence of axial current conservation, fermions cannot be bound in localized lumps in the massless Nambu-Jona-Lasinio model. In the case of twisted kinks, this manifests itself in a cancellation between the valence fermion density and the fermion density induced in the Dirac sea. To attribute the correct fermion number to these bound states requires an infrared regularization. Recently, this has been achieved by introducing a bare fermion mass, at least in the nonrelativistic regime of small twist angles and fermion numbers. Here, we propose a simpler regularization using a finite box which preserves integrability and can be applied at any twist angle. A consistent and physically plausible assignment of fermion number to all twisted kinks emerges.

  18. Visualizing the chiral anomaly in Dirac and Weyl semimetals with photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Behrends, Jan; Grushin, Adolfo G.; Ojanen, Teemu; Bardarson, Jens H.

    2016-02-01

    Quantum anomalies are the breaking of a classical symmetry by quantum fluctuations. They dictate how physical systems of diverse nature, ranging from fundamental particles to crystalline materials, respond topologically to external perturbations, insensitive to local details. The anomaly paradigm was triggered by the discovery of the chiral anomaly that contributes to the decay of pions into photons and influences the motion of superfluid vortices in 3He-A. In the solid state, it also fundamentally affects the properties of topological Weyl and Dirac semimetals, recently realized experimentally. In this work we propose that the most identifying consequence of the chiral anomaly, the charge density imbalance between fermions of different chirality induced by nonorthogonal electric and magnetic fields, can be directly observed in these materials with the existing technology of photoemission spectroscopy. With angle resolution, the chiral anomaly is identified by a characteristic note-shaped pattern of the emission spectra, originating from the imbalanced occupation of the bulk states and a previously unreported momentum dependent energy shift of the surface state Fermi arcs. We further demonstrate that the chiral anomaly likewise leaves an imprint in angle averaged emission spectra, facilitating its experimental detection. Thereby, our work provides essential theoretical input to foster the direct visualization of the chiral anomaly in condensed matter, in contrast to transport properties, such as negative magnetoresistance, which can also be obtained in the absence of a chiral anomaly.

  19. Annihilation of singlet fermionic dark matter into two photons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ettefaghi, M.M.; Moazzemi, R., E-mail: mettefaghi@qom.ac.ir, E-mail: r.moazzemi@qom.ac.ir

    2013-02-01

    We consider an extension of the standard model in which a singlet fermionic particle, to serve as cold dark matter, and a singlet Higgs are added. We perform a reanalysis on the free parameters. In particular, demanding a correct relic abundance of dark matter, we derive and plot the coupling of the singlet fermion with the singlet Higgs, g{sub s}, versus the dark matter mass. We analytically compute the pair annihilation cross section of singlet fermionic dark matter into two photons. The thermally averaged of this cross section is calculated for wide range of energies and plotted versus dark mattermore » mass using g{sub s} consistent with the relic abundance condition. We also compare our results with the Fermi-Lat observations.« less

  20. Chiral vortical effect generated by chiral anomaly in vortex-skyrmions

    NASA Astrophysics Data System (ADS)

    Volovik, G. E.

    2017-03-01

    We discuss the type of the general macroscopic parity-violating effects, when there is the current along the vortex, which is concentrated in the vortex core. We consider vortices in chiral superfluids with Weyl points. In the vortex core, the positions of the Weyl points form the skyrmion structure. We show that the mass current concentrated in such a core is provided by the spectral flow through the Weyl points according to the Adler-Bell-Jackiw equation for chiral anomaly.

  1. Competing forces in five-dimensional fermion condensation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yoon, Jongmin; Peskin, Michael E.

    We study fermion condensation in the Randall-Sundrum background as a setting for composite Higgs models. We formalize the computation of the Coleman-Weinberg potential and present a simple, general formula. Using this tool, we study the competition of fermion multiplets with different boundary conditions, to find conditions for creating a little hierarchy with the Higgs field expectation value much smaller than the intrinsic Randall-Sundrum mass scale.

  2. Competing forces in five-dimensional fermion condensation

    DOE PAGES

    Yoon, Jongmin; Peskin, Michael E.

    2017-12-27

    We study fermion condensation in the Randall-Sundrum background as a setting for composite Higgs models. We formalize the computation of the Coleman-Weinberg potential and present a simple, general formula. Using this tool, we study the competition of fermion multiplets with different boundary conditions, to find conditions for creating a little hierarchy with the Higgs field expectation value much smaller than the intrinsic Randall-Sundrum mass scale.

  3. Competing forces in five-dimensional fermion condensation

    NASA Astrophysics Data System (ADS)

    Yoon, Jongmin; Peskin, Michael E.

    2017-12-01

    We study fermion condensation in the Randall-Sundrum background as a setting for composite Higgs models. We formalize the computation of the Coleman-Weinberg potential and present a simple, general formula. Using this tool, we study the competition of fermion multiplets with different boundary conditions, to find conditions for creating a little hierarchy with the Higgs field expectation value much smaller than the intrinsic Randall-Sundrum mass scale.

  4. On stability, chirality measures, and theoretical VCD spectra of the chiral C58X2 fullerenes (X = N, B).

    PubMed

    Ostrowski, Sławomir; Jamróz, Michał H; Rode, Joanna E; Dobrowolski, Jan Cz

    2012-01-12

    The stability of all 23 C(58)N(2) and C(58)B(2) heterofullerenes in the singlet and triplet states was determined at the B3LYP/6-31G** level. In equilibrium mixture the achiral (1,4) C(58)N(2) isomer would be populated in ca. 95.8%, the chiral (1,16) one in ca. 3.3%, and the achiral (1,4) C(58)B(2) in 100%, whereas all triplet state isomers are less stable. Fourteen out of 23 C(58)X(2) are chiral. Four different chirality measures were calculated by our own CHIMEA program: pure geometrical, labeled, mass, and charge. Intercorrelations between the measures for all chiral compounds indicate that the pure geometrical chirality measure is unstable and should not be used in QSAR predictions of the other molecular properties, while the labeled and mass-weighted ones are promising QSAR descriptors. For each chiral C(58)N(2) molecule, some very strong VCD bands, of intensity comparable with that in the IR spectra, can serve in identification and characterization of the isomers.

  5. Implications of Higgs Universality for neutrinos

    NASA Astrophysics Data System (ADS)

    Stephenson, Gerard; Goldman, T.

    2017-09-01

    Higgs Universality means that the right-chiral Weyl spinors of each charge type couple universally to the Higgs doublet-left-chiral Weyl spinor weak singlets for quarks in the current basis,so the quark mass matrices are of the pairing form. We have shown that the known quark masses and weak current mixing can be recovered by invoking perturbative BSM corrections. The application to the charged leptons is immediate. Assuming the charged fermion-like mass terms for the neutrinos have a similar structure, but that Majorana mass terms for the sterile right-chiral spinors (which qualify as dark matter) must also be included, we show that the ratios of the resulting sterile neutrino masses vary as the square of the ratios of the charged fermion masses. The results are consistent with short-baseline neutrino oscillation experiments. Using that scale, we predict sterile neutrinos at masses of several keV/c2 and some tens of MeV /c2 , which may decay to a photon and a lighter neutrino.

  6. Flavor-singlet meson decay constants from Nf=2 +1 +1 twisted mass lattice QCD

    NASA Astrophysics Data System (ADS)

    Ottnad, Konstantin; Urbach, Carsten; ETM Collaboration

    2018-03-01

    We present an improved analysis of our lattice data for the η - η' system, including a correction of the relevant correlation functions for residual topological finite size effects and employing consistent chiral and continuum fits. From this analysis we update our physical results for the masses Mη=557 (11 )stat(03 )χ PT MeV and Mη'=911 (64 )stat(03 )χ PT MeV , as well as the mixing angle in the quark flavor basis ϕ =38.8 (2.2 )stat(2.4 )χPT ∘ in excellent agreement with other results from phenomenology. Similarly, we include an analysis for the decay constant parameters, leading to fl=125 (5 )stat(6 )χ PT MeV and fs=178 (4 )stat(1 )χ PT MeV . The second error reflects the uncertainty related to the chiral extrapolation. The data used for this study has been generated on gauge ensembles provided by the European Twisted Mass Collaboration with Nf=2 +1 +1 dynamical flavors of Wilson twisted mass fermions. These ensembles cover a range of pion masses from 220 MeV to 500 MeV and three values of the lattice spacing. Combining our data with a prediction from chiral perturbation theory, we give an estimate for the physical η , η'→γ γ decay widths and the singly-virtual η , η'→γ γ* transition form factors in the limit of large momentum transfer.

  7. All-optical materials design of chiral edge modes in transition-metal dichalcogenides

    PubMed Central

    Claassen, Martin; Jia, Chunjing; Moritz, Brian; Devereaux, Thomas P.

    2016-01-01

    Monolayer transition-metal dichalcogenides are novel materials which at low energies constitute a condensed-matter realization of massive relativistic fermions in two dimensions. Here, we show that this picture breaks for optical pumping—instead, the added complexity of a realistic materials description leads to a new mechanism to optically induce topologically protected chiral edge modes, facilitating optically switchable conduction channels that are insensitive to disorder. In contrast to graphene and previously discussed toy models, the underlying mechanism relies on the intrinsic three-band nature of transition-metal dichalcogenide monolayers near the band edges. Photo-induced band inversions scale linearly in applied pump field and exhibit transitions from one to two chiral edge modes on sweeping from red to blue detuning. We develop an ab initio strategy to understand non-equilibrium Floquet–Bloch bands and topological transitions, and illustrate for WS2 that control of chiral edge modes can be dictated solely from symmetry principles and is not qualitatively sensitive to microscopic materials details. PMID:27721504

  8. New type of Weyl semimetal with quadratic double Weyl fermions

    DOE PAGES

    Huang, Shin -Ming; Xu, Su -Yang; Belopolski, Ilya; ...

    2016-01-19

    Weyl semimetals have attracted worldwide attention due to their wide range of exotic properties predicted in theories. The experimental realization had remained elusive for a long time despite much effort. Very recently, the first Weyl semimetal has been discovered in an inversion-breaking, stoichiometric solid TaAs. So far, the TaAs class remains the only Weyl semimetal available in real materials. To facilitate the transition of Weyl semimetals from the realm of purely theoretical interest to the realm of experimental studies and device applications, it is of crucial importance to identify other robust candidates that are experimentally feasible to be realized. Inmore » this paper, we propose such a Weyl semimetal candidate in an inversion-breaking, stoichiometric compound strontium silicide, SrSi 2, with many new and novel properties that are distinct from TaAs. Here, we show that SrSi 2 is a Weyl semimetal even without spin-orbit coupling and that, after the inclusion of spin-orbit coupling, two Weyl fermions stick together forming an exotic double Weyl fermion with quadratic dispersions and a higher chiral charge of ±2. Moreover, we find that the Weyl nodes with opposite charges are located at different energies due to the absence of mirror symmetry in SrSi 2, paving the way for the realization of the chiral magnetic effect. Finally, our systematic results not only identify a much-needed robust Weyl semimetal candidate but also open the door to new topological Weyl physics that is not possible in TaAs« less

  9. Singlet fermionic dark matter with Veltman conditions

    NASA Astrophysics Data System (ADS)

    Kim, Yeong Gyun; Lee, Kang Young; Nam, Soo-hyeon

    2018-07-01

    We reexamine a renormalizable model of a fermionic dark matter with a gauge singlet Dirac fermion and a real singlet scalar which can ameliorate the scalar mass hierarchy problem of the Standard Model (SM). Our model setup is the minimal extension of the SM for which a realistic dark matter (DM) candidate is provided and the cancellation of one-loop quadratic divergence to the scalar masses can be achieved by the Veltman condition (VC) simultaneously. This model extension, although renormalizable, can be considered as an effective low-energy theory valid up to cut-off energies about 10 TeV. We calculate the one-loop quadratic divergence contributions of the new scalar and fermionic DM singlets, and constrain the model parameters using the VC and the perturbative unitarity conditions. Taking into account the invisible Higgs decay measurement, we show the allowed region of new physics parameters satisfying the recent measurement of relic abundance. With the obtained parameter set, we predict the elastic scattering cross section of the new singlet fermion into target nuclei for a direct detection of the dark matter. We also perform the full analysis with arbitrary set of parameters without the VC as a comparison, and discuss the implication of the constraints by the VC in detail.

  10. Connected and disconnected contributions to nucleon axial form factors using Nf = 2 twisted mass fermions at the physical point

    NASA Astrophysics Data System (ADS)

    Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Jansen, Karl; Kallidonis, Christos; Koutsou, Giannis; Vaquero Avilés-Casco, Alejandro

    2018-03-01

    We present results on the isovector and isoscalar nucleon axial form factors including disconnected contributions, using an ensemble of Nf = 2 twisted mass cloverimproved Wilson fermions simulated with approximately the physical value of the pion mass. The light disconnected quark loops are computed using exact deflation, while the strange and the charm quark loops are evaluated using the truncated solver method. Techniques such as the summation and the two-state fits have been employed to access ground-state dominance.

  11. Local Hamiltonian Monte Carlo study of the massive schwinger model, the decoupling of heavy flavours

    NASA Astrophysics Data System (ADS)

    Ranft, J.

    1983-12-01

    The massive Schwinger model with two flavours is studied using the local hamiltonian lattice Monte Carlo method. Chiral symmetry breaking is studied using the fermion condensate as order parameter. For a small ratio of the two fermion masses, degeneracy of the two flavours is found. For a large ratio of the masses, the heavy flavour decouples and the light fermion behaves like in the one flavour Schwinger model. On leave from Sektion Physik, Karl-Marx-Universität, Leipzig, GDR.

  12. Kaon B-parameter in mixed action chiral perturbation theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aubin, C.; Laiho, Jack; Water, Ruth S. van de

    2007-02-01

    We calculate the kaon B-parameter, B{sub K}, in chiral perturbation theory for a partially quenched, mixed-action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We find that the resulting expression is similar to that in the continuum, and in fact has only two additional unknown parameters. At 1-loop order, taste-symmetry violations in the staggered sea sector only contribute to flavor-disconnected diagrams by generating an O(a{sup 2}) shift to the masses of taste-singlet sea-sea mesons. Lattice discretization errors also give rise to an analytic term which shifts the tree-level value of B{sub K} by an amount of O(a{sup 2}). Thismore » term, however, is not strictly due to taste breaking, and is therefore also present in the expression for B{sub K} for pure Ginsparg-Wilson lattice fermions. We also present a numerical study of the mixed B{sub K} expression in order to demonstrate that both discretization errors and finite volume effects are small and under control on the MILC improved staggered lattices.« less

  13. Neutral kaon mixing beyond the Standard Model with n f = 2 + 1 chiral fermions. Part 2: non perturbative renormalisation of the ΔF = 2 four-quark operators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boyle, Peter A.; Garron, Nicolas; Hudspith, Renwick J.

    We compute the renormalisation factors (Z-matrices) of the ΔF = 2 four-quark operators needed for Beyond the Standard Model (BSM) kaon mixing. We work with nf = 2+1 flavours of Domain-Wall fermions whose chiral-flavour properties are essential to maintain a continuum-like mixing pattern. We introduce new RI-SMOM renormalisation schemes, which we argue are better behaved compared to the commonly-used corresponding RI-MOM one. We find that, once converted to MS¯, the Z-factors computed through these RI-SMOM schemes are in good agreement but differ significantly from the ones computed through the RI-MOM scheme. The RI-SMOM Z-factors presented here have been used tomore » compute the BSM neutral kaon mixing matrix elements in the companion paper. In conclusion, we argue that the renormalisation procedure is responsible for the discrepancies observed by different collaborations, we will investigate and elucidate the origin of these differences throughout this work.« less

  14. Neutral kaon mixing beyond the Standard Model with n f = 2 + 1 chiral fermions. Part 2: non perturbative renormalisation of the ΔF = 2 four-quark operators

    DOE PAGES

    Boyle, Peter A.; Garron, Nicolas; Hudspith, Renwick J.; ...

    2017-10-10

    We compute the renormalisation factors (Z-matrices) of the ΔF = 2 four-quark operators needed for Beyond the Standard Model (BSM) kaon mixing. We work with nf = 2+1 flavours of Domain-Wall fermions whose chiral-flavour properties are essential to maintain a continuum-like mixing pattern. We introduce new RI-SMOM renormalisation schemes, which we argue are better behaved compared to the commonly-used corresponding RI-MOM one. We find that, once converted to MS¯, the Z-factors computed through these RI-SMOM schemes are in good agreement but differ significantly from the ones computed through the RI-MOM scheme. The RI-SMOM Z-factors presented here have been used tomore » compute the BSM neutral kaon mixing matrix elements in the companion paper. In conclusion, we argue that the renormalisation procedure is responsible for the discrepancies observed by different collaborations, we will investigate and elucidate the origin of these differences throughout this work.« less

  15. Neutral kaon mixing beyond the Standard Model with n f = 2 + 1 chiral fermions. Part 2: non perturbative renormalisation of the Δ F = 2 four-quark operators

    NASA Astrophysics Data System (ADS)

    Boyle, Peter A.; Garron, Nicolas; Hudspith, Renwick J.; Lehner, Christoph; Lytle, Andrew T.

    2017-10-01

    We compute the renormalisation factors ( Z-matrices) of the Δ F = 2 four-quark operators needed for Beyond the Standard Model (BSM) kaon mixing. We work with n f = 2+1 flavours of Domain-Wall fermions whose chiral-flavour properties are essential to maintain a continuum-like mixing pattern. We introduce new RI-SMOM renormalisation schemes, which we argue are better behaved compared to the commonly-used corresponding RI-MOM one. We find that, once converted to \\overline{MS} , the Z-factors computed through these RI-SMOM schemes are in good agreement but differ significantly from the ones computed through the RI-MOM scheme. The RI-SMOM Z-factors presented here have been used to compute the BSM neutral kaon mixing matrix elements in the companion paper [1]. We argue that the renormalisation procedure is responsible for the discrepancies observed by different collaborations, we will investigate and elucidate the origin of these differences throughout this work.

  16. Infrared dynamics of minimal walking technicolor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Del Debbio, Luigi; Lucini, Biagio; Patella, Agostino

    2010-07-01

    We study the gauge sector of minimal walking technicolor, which is an SU(2) gauge theory with n{sub f}=2 flavors of Wilson fermions in the adjoint representation. Numerical simulations are performed on lattices N{sub t}xN{sub s}{sup 3}, with N{sub s} ranging from 8 to 16 and N{sub t}=2N{sub s}, at fixed {beta}=2.25, and varying the fermion bare mass m{sub 0}, so that our numerical results cover the full range of fermion masses from the quenched region to the chiral limit. We present results for the string tension and the glueball spectrum. A comparison of mesonic and gluonic observables leads to themore » conclusion that the infrared dynamics is given by an SU(2) pure Yang-Mills theory with a typical energy scale for the spectrum sliding to zero with the fermion mass. The typical mesonic mass scale is proportional to and much larger than this gluonic scale. Our findings are compatible with a scenario in which the massless theory is conformal in the infrared. An analysis of the scaling of the string tension with the fermion mass toward the massless limit allows us to extract the chiral condensate anomalous dimension {gamma}{sub *}, which is found to be {gamma}{sub *}=0.22{+-}0.06.« less

  17. Dynamical Mass Generation.

    NASA Astrophysics Data System (ADS)

    Mendel Horwitz, Roberto Ruben

    1982-03-01

    In the framework of the Glashow-Weinberg-Salem model without elementary scalar particles, we show that masses for fermions and intermediate vector bosons can be generated dynamically. The mechanism is the formation of fermion-antifermion pseudoscalar bound states of zero total four momentum, which form a condensate in the physical vacuum. The force responsible for the binding is the short distance part of the net Coulomb force due to photon and Z exchange. Fermions and bosons acquire masses through their interaction with this condensate. The neutrinos remain massless because their righthanded components have no interactions. Also the charge -1/3 quarks remain massless because the repulsive force from the Z exchange dominates over the Coulomb force. To correct this, we propose two possible modifications to the theory. One is to cut off the Z exchange at very small distances, so that all fermions except the neutrinos acquire masses, which are then, purely electromagnetic in origin. The other is to introduce an additional gauge boson that couples to all quarks with a pure vector coupling. To make this vector boson unobservable at usual energies, at least two new fermions must couple to it. The vector boson squared masses receive additive contributions from all the fermion squared masses. The photon remains massless and the masses of the Z and W('(+OR -)) bosons are shown to be related through the Weinberg angle in the conventional way. Assuming only three families of fermions, we obtain estimates for the top quark mass.

  18. Fermion dark matter in gauge-Higgs unification

    DOE PAGES

    Maru, Nobuhito; Miyaji, Takashi; Okada, Nobuchika; ...

    2017-07-11

    Here, we propose a Majorana fermion dark matter in the context of a s imple gauge-Higgs Unification (GHU) scenario based on the gauge group SU(3)×U(1)' in 5-dimensional Minkowski space with a compactification of the 5th dimension on S 1/Z 2 orbifold. The dark matter particle is identified with the lightest mode in SU(3) triplet fermions additionally introduced in the 5-dimensional bulk. We find an allowed parameter region for the dark matter mass around a half of the Standard Model Higgs boson mass, which is consistent with the observed dark matter density and the constraint from the LUX 2016 result formore » the direct dark matter search. The entire allowed region will be covered by, for example, the LUX-ZEPLIN dark matter experiment in the near future. We also show that in the presence of the bulk SU(3) triplet fermions the 125 GeV Higgs boson mas s is reproduced through the renormalization group evolution of Higgs quartic coupling with the compactification scale of around 10 8 GeV.« less

  19. Coleman-Weinberg symmetry breaking in SU(8) induced by a third rank antisymmetric tensor scalar field II: the fermion spectrum

    NASA Astrophysics Data System (ADS)

    Adler, Stephen L.

    2017-07-01

    We continue our study of Coleman-Weinberg symmetry breaking induced by a third rank antisymmetric tensor scalar, in the context of the SU(8) model (Adler 2014 Int. J. Mod. Phys. A 29 1450130) we proposed earlier. We focus in this paper on qualitative features that will determine whether the model can make contact with the observed particle spectrum. We discuss the mechanism for giving the spin \\frac{3}{2} field a mass by the BEH mechanism, and analyze the remaining massless spin \\frac{1}{2} fermions, the global chiral symmetries, and the running couplings after symmetry breaking. We note that the smallest gluon mass matrix eigenvalue has an eigenvector suggestive of U(1) B-L , and conjecture that the theory runs to an infrared fixed point at which there is a massless gluon with 3 to  -1 ratios in generator components. Assuming this, we discuss a mechanism for making contact with the standard model, based on a conjectured asymmetric breaking of Sp(4) to SU(2) subgroups, one of which is the electroweak SU(2), and the other of which is a ‘technicolor’ group that binds the original SU(8) model fermions, which play the role of ‘preons’, into composites. Quarks can emerge as 5 preon composites and leptons as 3 preon composites, with consequent stability of the proton against decay to a single lepton plus a meson. A composite Higgs boson can emerge as a two preon composite. Since anomaly matching for the relevant conserved global symmetry current is not obeyed by three fermion families, emergence of three composite families requires formation of a Goldstone boson with quantum numbers matching this current, which can be a light dark matter candidate.

  20. Chiral Luttinger liquids and a generalized Luttinger theorem in fractional quantum Hall edges via finite-entanglement scaling

    NASA Astrophysics Data System (ADS)

    Varjas, Dániel; Zaletel, Michael P.; Moore, Joel E.

    2013-10-01

    We use bosonic field theories and the infinite system density matrix renormalization group method to study infinite strips of fractional quantum Hall states starting from microscopic Hamiltonians. Finite-entanglement scaling allows us to accurately measure chiral central charge, edge-mode exponents, and momenta without finite-size errors. We analyze states in the first and second levels of the standard hierarchy and compare our results to predictions of the chiral Luttinger liquid theory. The results confirm the universality of scaling exponents in chiral edges and demonstrate that renormalization is subject to universal relations in the nonchiral case. We prove a generalized Luttinger theorem involving all singularities in the momentum-resolved density, which naturally arises when mapping Landau levels on a cylinder to a fermion chain and deepens our understanding of non-Fermi liquids in one dimension.

  1. Non-stationary measurements of Chiral Magnetic Effect

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shevchenko, V.I., E-mail: vladimir.i.shevchenko@gmail.com

    2013-12-15

    We discuss the Chiral Magnetic Effect from the quantum theory of measurements point of view for non-stationary measurements. The effect of anisotropy for fluctuations of electric currents in a magnetic field is addressed. It is shown that anisotropy caused by nonzero axial chemical potential is indistinguishable in this framework from anisotropy caused by finite measurement time or finite lifetime of the magnetic field, and in all cases it is related to abelian triangle anomaly. Possible P-odd effects in central heavy-ion collisions (where the Chiral Magnetic Effect is absent) are discussed in this context. This paper is dedicated to the memorymore » of Professor Mikhail Polikarpov (1952–2013). -- Highlights: •Asymmetry in the response function for vector currents of massless fermions in the magnetic field is computed. •Asymmetry caused by axial chemical potential is practically indistinguishable from the one caused by non-stationarity. •The CME current is non-dissipative in the stationary case and dissipative in the non-stationary case. •Importance of studies of P-odd signatures in central collisions is emphasized.« less

  2. Chiral phase structure of three flavor QCD at vanishing baryon number density

    DOE PAGES

    Bazavov, A.; Ding, H. -T.; Hegde, P.; ...

    2017-04-12

    In this paper, we investigate the phase structure of QCD with three degenerate quark flavors as a function of the degenerate quark masses at vanishing baryon number density. We use the highly improved staggered quarks on lattices with temporal extent N τ = 6 and perform calculations for six values of quark masses, which in the continuum limit correspond to pion masses in the range 80 MeV ≲ m π ≲ 230 MeV. By analyzing the volume and temperature dependence of the chiral condensate and chiral susceptibility, we find no direct evidence for a first-order phase transition in this rangemore » of pion mass values. Finally, relying on the universal scaling behaviors of the chiral observables near an anticipated chiral critical point, we estimate an upper bound for the critical pion mass m c π ≲ 50 MeV, below which a region of first-order chiral phase transition is favored.« less

  3. Heavy fermion behavior explained by bosons

    NASA Technical Reports Server (NTRS)

    Kallio, A.; Poykko, S.; Apaja, V.

    1995-01-01

    Conventional heavy fermion (HF) theories require existence of massive fermions. We show that heavy fermion phenomena can also be simply explained by existence of bosons with moderate mass but temperature dependent concentration below the formation temperature T(sub B), which in turn is close to room temperature. The bosons B(++) are proposed to be in chemical equilibrium with a system of holes h(+): B(++) = h(+) + h(+). This equilibrium is governed by a boson breaking function f(T), which determines the decreasing boson density and the increasing fermion density with increasing temperature. Since HF-compounds are hybridized from minimum two elements, we assume in addition existence of another fermion component h(sub s)(+) with temperature independent density. This spectator component is thought to be the main agent in binding the bosons in analogy with electronic or muonic molecules. Using a linear boson breaking function we can explain temperature dependence of the giant linear specific heat coefficient gamma(T) coming essentially from bosons. The maxima in resistivity, Hall coefficient, and susceptibility are explained by boson localization effects due to the Wigner crystallization. The antiferromagnetic transitions in turn are explained by similar localization of the pairing fermion system when their density n(sub h)(T(sub FL)) becomes lower than n(sub WC), the critical density of Wigner crystallization. The model applies irrespective whether a compound is superconducting or not. The same model explains the occurrence of low temperature antiferromagnetism also in high-T(sub c) superconductors. The double transition in UPt3 is proposed to be due to the transition of the pairing fermion liquid from spin polarized to unpolarized state.

  4. Hierarchical fermions and detectable Z' from effective two-Higgs-triplet 3-3-1 model

    NASA Astrophysics Data System (ADS)

    Barreto, E. R.; Dias, A. G.; Leite, J.; Nishi, C. C.; Oliveira, R. L. N.; Vieira, W. C.

    2018-03-01

    We develop a SU (3 )C⊗SU (3 )L⊗U (1 )X model where the number of fermion generations is fixed by cancellation of gauge anomalies, being a type of 3-3-1 model with new charged leptons. Similarly to the economical 3-3-1 models, symmetry breaking is achieved effectively with two scalar triplets so that the spectrum of scalar particles at the TeV scale contains just two C P even scalars, one of which is the recently discovered Higgs boson, plus a charged scalar. Such a scalar sector is simpler than the one in the Two Higgs Doublet Model, hence more attractive for phenomenological studies, and has no flavor changing neutral currents (FCNC) mediated by scalars except for the ones induced by the mixing of Standard Model (SM) fermions with heavy fermions. We identify a global residual symmetry of the model which guarantees mass degeneracies and some massless fermions whose masses need to be generated by the introduction of effective operators. The fermion masses so generated require less fine-tuning for most of the SM fermions and FCNC are naturally suppressed by the small mixing between the third family of quarks and the rest. The effective setting is justified by an ultraviolet completion of the model from which the effective operators emerge naturally. A detailed particle mass spectrum is presented, and an analysis of the Z' production at the LHC run II is performed to show that it could be easily detected by considering the invariant mass and transverse momentum distributions in the dimuon channel.

  5. Localization and oscillations of Majorana fermions in a two-dimensional electron gas coupled with d -wave superconductors

    NASA Astrophysics Data System (ADS)

    Ortiz, L.; Varona, S.; Viyuela, O.; Martin-Delgado, M. A.

    2018-02-01

    We study the localization and oscillation properties of the Majorana fermions that arise in a two-dimensional electron gas (2DEG) with spin-orbit coupling (SOC) and a Zeeman field coupled with a d -wave superconductor. Despite the angular dependence of the d -wave pairing, localization and oscillation properties are found to be similar to the ones seen in conventional s -wave superconductors. In addition, we study a microscopic lattice version of the previous system that can be characterized by a topological invariant. We derive its real space representation that involves nearest and next-to-nearest-neighbors pairing. Finally, we show that the emerging chiral Majorana fermions are indeed robust against static disorder. This analysis has potential applications to quantum simulations and experiments in high-Tc superconductors.

  6. Catalysis of partial chiral symmetry restoration by Δ matter

    NASA Astrophysics Data System (ADS)

    Takeda, Yusuke; Kim, Youngman; Harada, Masayasu

    2018-06-01

    We study the phase structure of dense hadronic matter including Δ (1232 ) as well as N (939 ) based on the parity partner structure, where the baryons have their chiral partners with a certain amount of chiral invariant masses. We show that, in symmetric matter, Δ enters into matter in the density region of about one to four times normal nuclear matter density, ρB˜1 -4 ρ0 . The onset density of Δ matter depends on the chiral invariant mass of Δ ,mΔ 0 : As mΔ 0 increases, the onset density becomes bigger. The stable Δ -nucleon matter is realized for ρB≳1.5 ρ0 , i.e., the phase transition from nuclear matter to Δ -nucleon matter is of first order for small mΔ 0, and it is of second order for large mΔ 0. We find that, associated with the phase transition, the chiral condensate changes very rapidly; i.e., the chiral symmetry restoration is accelerated by Δ matter. As a result of the accelerations, there appear N*(1535 ) and Δ (1700 ) , which are the chiral partners to N (939 ) and Δ (1232 ) , in high-density matter, signaling the partial chiral symmetry restoration. Furthermore, we find that complete chiral symmetry restoration itself is delayed by Δ matter. We also calculate the effective masses, pressure, and symmetry energy to study how the transition to Δ matter affects such physical quantities. We observe that the physical quantities change drastically at the transition density.

  7. Effects of flavor-symmetry violation from staggered fermion lattice simulations of graphene

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Giedt, Joel; Nayak, Saroj; Skinner, Andrew

    2011-01-15

    We analyze the effects of flavor splitting from staggered fermion lattice simulations of a low-energy effective theory for graphene. Both the unimproved action and the tadpole-improved action with a Naik term show significant flavor-symmetry breaking in the spectrum of the Dirac operator. Note that this is true even in the vicinity of the second-order phase transition point where it has been argued that the flavor-symmetry breaking should be small due to the continuum limit being approached. We show that at weaker couplings the flavor splitting is drastically reduced by stout link smearing, while this mechanism is ineffective at the strongermore » couplings relevant to suspended graphene. We also measure the average plaquette and describe how it calls for a reinterpretation of previous lattice Monte Carlo simulation results, due to tadpole improvement. After taking into account these effects, we conclude that previous lattice simulations are possibly indicative of an insulating phase, although the effective number of light flavors could be effectively less than two due to the flavor-splitting effects. If that is true, then simulations with truly chiral fermions (such as overlap fermions) are needed in order to settle the question.« less

  8. Auxiliary-field quantum Monte Carlo simulations of neutron matter in chiral effective field theory.

    PubMed

    Wlazłowski, G; Holt, J W; Moroz, S; Bulgac, A; Roche, K J

    2014-10-31

    We present variational Monte Carlo calculations of the neutron matter equation of state using chiral nuclear forces. The ground-state wave function of neutron matter, containing nonperturbative many-body correlations, is obtained from auxiliary-field quantum Monte Carlo simulations of up to about 340 neutrons interacting on a 10(3) discretized lattice. The evolution Hamiltonian is chosen to be attractive and spin independent in order to avoid the fermion sign problem and is constructed to best reproduce broad features of the chiral nuclear force. This is facilitated by choosing a lattice spacing of 1.5 fm, corresponding to a momentum-space cutoff of Λ=414  MeV/c, a resolution scale at which strongly repulsive features of nuclear two-body forces are suppressed. Differences between the evolution potential and the full chiral nuclear interaction (Entem and Machleidt Λ=414  MeV [L. Coraggio et al., Phys. Rev. C 87, 014322 (2013).

  9. Fermionic influence on inflationary fluctuations

    NASA Astrophysics Data System (ADS)

    Boyanovsky, Daniel

    2016-04-01

    Motivated by apparent persistent large scale anomalies in the cosmic microwave background we study the influence of fermionic degrees of freedom on the dynamics of inflaton fluctuations as a possible source of violations of (nearly) scale invariance on cosmological scales. We obtain the nonequilibrium effective action of an inflaton-like scalar field with Yukawa interactions (YD ,M) to light fermionic degrees of freedom both for Dirac and Majorana fields in de Sitter space-time. The effective action leads to Langevin equations of motion for the fluctuations of the inflaton-like field, with self-energy corrections and a stochastic Gaussian noise. We solve the Langevin equation in the super-Hubble limit implementing a dynamical renormalization group resummation. For a nearly massless inflaton its power spectrum of super-Hubble fluctuations is enhanced, P (k ;η )=(H/2 π )2eγt[-k η ] with γt[-k η ]=1/6 π2 [∑i =1 NDYi,D 2+2 ∑j =1 NMYj,M 2]{ln2[-k η ]-2 ln [-k η ]ln [-k η0]} for ND Dirac and NM Majorana fermions, and η0 is the renormalization scale at which the inflaton mass vanishes. The full power spectrum is shown to be renormalization group invariant. These corrections to the super-Hubble power spectrum entail a violation of scale invariance as a consequence of the coupling to the fermionic fields. The effective action is argued to be exact in the limit of a large number of fermionic fields. A cancellation between the enhancement from fermionic degrees of freedom and suppression from light scalar degrees of freedom conformally coupled to gravity suggests the possibility of a finely tuned supersymmetry among these fields.

  10. All-optical materials design of chiral edge modes in transition-metal dichalcogenides

    DOE PAGES

    Claassen, Martin; Jia, Chunjing; Moritz, Brian; ...

    2016-10-10

    Monolayer transition-metal dichalcogenides are novel materials which at low energies constitute a condensed-matter realization of massive relativistic fermions in two dimensions. Here, we show that this picture breaks for optical pumping—instead, the added complexity of a realistic materials description leads to a new mechanism to optically induce topologically protected chiral edge modes, facilitating optically switchable conduction channels that are insensitive to disorder. In contrast to graphene and previously discussed toy models, the underlying mechanism relies on the intrinsic three-band nature of transition-metal dichalcogenide monolayers near the band edges. Photo-induced band inversions scale linearly in applied pump field and exhibit transitionsmore » from one to two chiral edge modes on sweeping from red to blue detuning. As a result, we develop an ab initio strategy to understand non-equilibrium Floquet–Bloch bands and topological transitions, and illustrate for WS 2 that control of chiral edge modes can be dictated solely from symmetry principles and is not qualitatively sensitive to microscopic materials details.« less

  11. Hydrodynamics with chiral anomaly and charge separation in relativistic heavy ion collisions

    DOE PAGES

    Yin, Yi; Liao, Jinfeng

    2016-03-03

    Matter with chiral fermions is microscopically described by theory with quantum anomaly and macroscopically described (at low energy) by anomalous hydrodynamics. For such systems in the presence of external magnetic field and chirality imbalance, a charge current is generated along the magnetic field direction ₋ a phenomenon known as the Chiral Magnetic Effect (CME). The quark- gluon plasma created in relativistic heavy ion collisions provides an (approximate) example, for which the CME predicts a charge separation perpendicular to the collisional reaction plane. Charge correlation measurements designed for the search of such signal have been done at RHIC and the LHCmore » for which the interpretations, however, remain unclear due to contamination by background effects that are collective flow driven, theoretically poorly constrained, and experimentally hard to separate. Using anomalous (and viscous) hydrodynamic simulations, we make a first attempt at quantifying contributions to observed charge correlations from both CME and background effects in one and same framework. We discuss the implications for the search of CME.« less

  12. Baryon spectrum of SU(4) composite Higgs theory with two distinct fermion representations

    NASA Astrophysics Data System (ADS)

    Ayyar, Venkitesh; DeGrand, Thomas; Hackett, Daniel C.; Jay, William I.; Neil, Ethan T.; Shamir, Yigal; Svetitsky, Benjamin

    2018-06-01

    We use lattice simulations to compute the baryon spectrum of SU(4) lattice gauge theory coupled to dynamical fermions in the fundamental and two-index antisymmetric (sextet) representations simultaneously. This model is closely related to a composite Higgs model in which the chimera baryon made up of fermions from both representations plays the role of a composite top-quark partner. The dependence of the baryon masses on each underlying fermion mass is found to be generally consistent with a quark-model description and large-Nc scaling. We combine our numerical results with experimental bounds on the scale of the new strong sector to estimate a lower bound on the mass of the top-quark partner. We discuss some theoretical uncertainties associated with this estimate.

  13. Fermion determinants in static, inhomogeneous magnetic fields

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fry, M.P.

    1995-01-15

    The renormalized fermionic determinant of QED in 3+1 dimensions, det[sub ren], in a static, unidirectional, inhomogeneous magnetic field with finite flux can be calculated from the massive Euclidean Schwinger model's determinant det[sub Sch] in the same field by integrating det[sub Sch] over the fermion's mass. Since det[sub ren] for general fields is central to QED, it is desirable to have nonperturbative information on this determinant, even for the restricted magnetic fields considered here. To this end we continue our study of the physically relevant determinant det[sub Sch]. It is shown that the contribution of the massless Schwinger model to det[submore » Sch] is canceled by a contribution from the massive sector of QED in 1+1 dimensions and that zero modes are suppressed in det[sub Sch]. We then calculate det[sub Sch] analytically in the presence of a finite flux, cylindrical magnetic field. Its behavior for large flux and small fermion mass suggests that the zero-energy bound states of the two-dimensional Pauli Hamiltonian are the controlling factor in the growth of ln det[sub Sch]. Evidence is presented that det[sub Sch] does not converge to the determinant of the massless Schwinger model in the small mass limit for finite, nonzero flux magnetic fields.« less

  14. CLS 2+1 flavor simulations at physical light-and strange-quark masses

    NASA Astrophysics Data System (ADS)

    Mohler, Daniel; Schaefer, Stefan; Simeth, Jakob

    2018-03-01

    We report recent efforts by CLS to generate an ensemble with physical lightand strange-quark masses in a lattice volume of 192 × 963 at β = 3:55 corresponding to a lattice spacing of 0:064 fm. This ensemble is being generated as part of the CLS 2+1 flavor effort with improved Wilson fermions. Our simulations currently cover 5 lattice spacings ranging from 0:039 fm to 0:086 fm at various pion masses along chiral trajectories with either the sum of the quark masses kept fixed, or with the strange-quark mass at the physical value. The current status of simulations is briefly reviewed, including a short discussion of measured autocorrelation times and of the main features of the simulations. We then proceed to discuss the thermalization strategy employed for the generation of the physical quark-mass ensemble and present first results for some simple observables. Challenges encountered in the simulation are highlighted.

  15. Chiral magnetic and vortical effects in high-energy nuclear collisions—A status report

    DOE PAGES

    Kharzeev, D. E.; Liao, J.; Voloshin, S. A.; ...

    2016-05-01

    Here, the interplay of quantum anomalies with magnetic field and vorticity results in a variety of novel non-dissipative transport phenomena in systems with chiral fermions, including the quark–gluon plasma. Among them is the Chiral Magnetic Effect (CME)—the generation of electric current along an external magnetic field induced by chirality imbalance. Because the chirality imbalance is related to the global topology of gauge fields, the CME current is topologically protected and hence non-dissipative even in the presence of strong interactions. As a result, the CME and related quantum phenomena affect the hydrodynamical and transport behavior of strongly coupled quark–gluon plasma, andmore » can be studied in relativistic heavy ion collisions where strong magnetic fields are created by the colliding ions. Evidence for the CME and related phenomena has been reported by the STAR Collaboration at Relativistic Heavy Ion Collider at BNL, and by the ALICE Collaboration at the Large Hadron Collider at CERN. The goal of the present review is to provide an elementary introduction into the physics of anomalous chiral effects, to describe the current status of experimental studies in heavy ion physics, and to outline the future work, both in experiment and theory, needed to eliminate the existing uncertainties in the interpretation of the data.« less

  16. Chiral phases of fundamental and adjoint quarks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Natale, A. A.; Instituto de Física Teórica - UNESP Rua Dr. Bento T. Ferraz, 271, Bl.II - 01140-070, São Paulo, SP

    2016-01-22

    We consider a QCD chiral symmetry breaking model where the gap equation contains an effective confining propagator and a dressed gluon propagator with a dynamically generated mass. This model is able to explain the ratios between the chiral transition and deconfinement temperatures in the case of fundamental and adjoint quarks. It also predicts the recovery of the chiral symmetry for a large number of quarks (n{sub f} ≈ 11 – 13) in agreement with lattice data.

  17. Chiral behavior of K →π l ν decay form factors in lattice QCD with exact chiral symmetry

    NASA Astrophysics Data System (ADS)

    Aoki, S.; Cossu, G.; Feng, X.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Noaki, J.; Onogi, T.; Jlqcd Collaboration

    2017-08-01

    We calculate the form factors of the K →π l ν semileptonic decays in three-flavor lattice QCD and study their chiral behavior as a function of the momentum transfer and the Nambu-Goldstone boson masses. Chiral symmetry is exactly preserved by using the overlap quark action, which enables us to directly compare the lattice data with chiral perturbation theory (ChPT). We generate gauge ensembles at a lattice spacing of 0.11 fm with four pion masses covering 290-540 MeV and a strange quark mass ms close to its physical value. By using the all-to-all quark propagator, we calculate the vector and scalar form factors with high precision. Their dependence on ms and the momentum transfer is studied by using the reweighting technique and the twisted boundary conditions for the quark fields. We compare the results for the semileptonic form factors with ChPT at next-to-next-to-leading order in detail. While many low-energy constants appear at this order, we make use of our data of the light meson electromagnetic form factors in order to control the chiral extrapolation. We determine the normalization of the form factors as f+(0 )=0.9636 (36 )(-35+57) and observe reasonable agreement of their shape with experiment.

  18. Chiral magnetic effect in the presence of electroweak interactions as a quasiclassical phenomenon

    NASA Astrophysics Data System (ADS)

    Dvornikov, Maxim; Semikoz, Victor B.

    2018-03-01

    We elaborate the quasiclassical approach to obtain the modified chiral magnetic effect (CME) in the case when the massless charged fermions interact with electromagnetic fields and the background matter by the electroweak forces. The derivation of the anomalous current along the external magnetic field involves the study of the energy density evolution of chiral particles in parallel electric and magnetic fields. We consider both the particle acceleration by the external electric field and the contribution of the Adler anomaly. The condition of the validity of this method for the derivation of the CME is formulated. We obtain the expression for the electric current along the external magnetic field, which appears to coincide with our previous results based on the purely quantum approach. Our results are compared with the findings of other authors.

  19. Heavy-light mesons in chiral AdS/QCD

    NASA Astrophysics Data System (ADS)

    Liu, Yizhuang; Zahed, Ismail

    2017-06-01

    We discuss a minimal holographic model for the description of heavy-light and light mesons with chiral symmetry, defined in a slab of AdS space. The model consists of a pair of chiral Yang-Mills and tachyon fields with specific boundary conditions that break spontaneously chiral symmetry in the infrared. The heavy-light spectrum and decay constants are evaluated explicitly. In the heavy mass limit the model exhibits both heavy-quark and chiral symmetry and allows for the explicit derivation of the one-pion axial couplings to the heavy-light mesons.

  20. IR properties of chiral effects in pionic matter

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Avdoshkin, A.; Sadofyev, A. V.; Zakharov, V. I.

    Chiral effects exhibit peculiar universality in idealized theoretical limits. However, they are known to be infrared sensitive and get modified in more realistic settings. In this work we study how the corresponding conductivities vary with the constituent mass. We concentrate on a pionic realization of chiral effects which provides a better control over infrared properties of the theory. The pionic medium is considered at finite vector and axial isospin chemical potentials in the presence of an external magnetic field. This system supports electric and axial isospin currents along the magnetic field which correspond to chiral magnetic and chiral separation effects.more » We show that these currents are sensitive to the finite mass of the constituents but the conductivities follow a simple scaling with the corresponding charge densities as one would expect for polarization effects. It is argued that this relation can capture the dependence of chiral effects on other infrared parameters. Finally, we briefly comment on the realization of the ’t Hooft matching condition in pionic media at finite densities.« less

  1. IR properties of chiral effects in pionic matter

    NASA Astrophysics Data System (ADS)

    Avdoshkin, A.; Sadofyev, A. V.; Zakharov, V. I.

    2018-04-01

    Chiral effects exhibit peculiar universality in idealized theoretical limits. However, they are known to be infrared sensitive and get modified in more realistic settings. In this work we study how the corresponding conductivities vary with the constituent mass. We concentrate on a pionic realization of chiral effects which provides a better control over infrared properties of the theory. The pionic medium is considered at finite vector and axial isospin chemical potentials in the presence of an external magnetic field. This system supports electric and axial isospin currents along the magnetic field which correspond to chiral magnetic and chiral separation effects. We show that these currents are sensitive to the finite mass of the constituents but the conductivities follow a simple scaling with the corresponding charge densities as one would expect for polarization effects. It is argued that this relation can capture the dependence of chiral effects on other infrared parameters. Finally, we briefly comment on the realization of the 't Hooft matching condition in pionic media at finite densities.

  2. IR properties of chiral effects in pionic matter

    DOE PAGES

    Avdoshkin, A.; Sadofyev, A. V.; Zakharov, V. I.

    2018-04-27

    Chiral effects exhibit peculiar universality in idealized theoretical limits. However, they are known to be infrared sensitive and get modified in more realistic settings. In this work we study how the corresponding conductivities vary with the constituent mass. We concentrate on a pionic realization of chiral effects which provides a better control over infrared properties of the theory. The pionic medium is considered at finite vector and axial isospin chemical potentials in the presence of an external magnetic field. This system supports electric and axial isospin currents along the magnetic field which correspond to chiral magnetic and chiral separation effects.more » We show that these currents are sensitive to the finite mass of the constituents but the conductivities follow a simple scaling with the corresponding charge densities as one would expect for polarization effects. It is argued that this relation can capture the dependence of chiral effects on other infrared parameters. Finally, we briefly comment on the realization of the ’t Hooft matching condition in pionic media at finite densities.« less

  3. Analyzing the Fierz rearrangement freedom for local chiral two-nucleon potentials

    NASA Astrophysics Data System (ADS)

    Huth, L.; Tews, I.; Lynn, J. E.; Schwenk, A.

    2017-11-01

    Chiral effective field theory is a framework to derive systematic nuclear interactions. It is based on the symmetries of quantum chromodynamics and includes long-range pion physics explicitly, while shorter-range physics is expanded in a general operator basis. The number of low-energy couplings at a particular order in the expansion can be reduced by exploiting the fact that nucleons are fermions and therefore obey the Pauli exclusion principle. The antisymmetry permits the selection of a subset of the allowed contact operators at a given order. When local regulators are used for these short-range interactions, however, this "Fierz rearrangement freedom" is violated. In this paper, we investigate the impact of this violation at leading order (LO) in the chiral expansion. We construct LO and next-to-leading order (NLO) potentials for all possible LO-operator pairs and study their reproduction of phase shifts, the 4He ground-state energy, and the neutron-matter energy at different densities. We demonstrate that the Fierz rearrangement freedom is partially restored at NLO where subleading contact interactions enter. We also discuss implications for local chiral three-nucleon interactions.

  4. Weyl points and Fermi arcs in a chiral phononic crystal

    NASA Astrophysics Data System (ADS)

    Li, Feng; Huang, Xueqin; Lu, Jiuyang; Ma, Jiahong; Liu, Zhengyou

    2018-01-01

    Topological semimetals are materials whose band structure contains touching points that are topologically nontrivial and can host quasiparticle excitations that behave as Dirac or Weyl fermions. These so-called Weyl points not only exist in electronic systems, but can also be found in artificial periodic structures with classical waves, such as electromagnetic waves in photonic crystals and acoustic waves in phononic crystals. Due to the lack of spin and a difficulty in breaking time-reversal symmetry for sound, however, topological acoustic materials cannot be achieved in the same way as electronic or optical systems. And despite many theoretical predictions, experimentally realizing Weyl points in phononic crystals remains challenging. Here, we experimentally realize Weyl points in a chiral phononic crystal system, and demonstrate surface states associated with the Weyl points that are topological in nature, and can host modes that propagate only in one direction. As with their photonic counterparts, chiral phononic crystals bring topological physics to the macroscopic scale.

  5. Staggered fermions, zero modes, and flavor-singlet mesons

    DOE PAGES

    Donald, Gordon C; Davies, Christine T.H.; Follana, Eduardo; ...

    2011-09-12

    We examine the taste structure of eigenvectors of the staggered-fermion Dirac operator. We derive a set of conditions on the eigenvectors of modes with small eigenvalues (near-zero modes), such that staggered fermions reproduce the 't Hooft vertex in the continuum limit. We also show that, assuming these conditions, the correlators of flavor-singlet mesons are free of contributions singular in 1/m, where m is the quark mass. This conclusion holds also when a single flavor of sea quark is represented by the fourth root of the staggered-fermion determinant. We then test numerically, using the HISQ action, whether these conditions hold onmore » realistic lattice gauge fields. We find that the needed structure does indeed emerge.« less

  6. Quantifying the chiral magnetic effect from anomalous-viscous fluid dynamics

    NASA Astrophysics Data System (ADS)

    Jiang, Yin; Shi, Shuzhe; Yin, Yi; Liao, Jinfeng

    2018-01-01

    The Chiral Magnetic Effect (CME) is a macroscopic manifestation of fundamental chiral anomaly in a many-body system of chiral fermions, and emerges as an anomalous transport current in the fluid dynamics framework. Experimental observation of the CME is of great interest and has been reported in Dirac and Weyl semimetals. Significant efforts have also been made to look for the CME in heavy ion collisions. Critically needed for such a search is the theoretical prediction for the CME signal. In this paper we report a first quantitative modeling framework, Anomalous Viscous Fluid Dynamics (AVFD), which computes the evolution of fermion currents on top of realistic bulk evolution in heavy ion collisions and simultaneously accounts for both anomalous and normal viscous transport effects. AVFD allows a quantitative understanding of the generation and evolution of CME-induced charge separation during the hydrodynamic stage, as well as its dependence on theoretical ingredients. With reasonable estimates of key parameters, the AVFD simulations provide the first phenomenologically successful explanation of the measured signal in 200 AGeV AuAu collisions. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, within the framework of the Beam Energy Scan Theory (BEST) Topical Collaboration. The work is also supported in part by the National Science Foundation under Grant No. PHY-1352368 (SS and JL), by the National Science Foundation of China under Grant No. 11735007 (JL) and by the U.S. Department of Energy under grant Contract Number No. DE- SC0012704 (BNL)/DE-SC0011090 (MIT) (YY). JL is grateful to the Institute for Nuclear Theory for hospitality during the INT-16-3 Program. The computation of this research was performed on IU’s Big Red II cluster, supported in part by Lilly Endowment, Inc. (through its support for the Indiana University Pervasive Technology Institute) and in part by the Indiana METACyt

  7. Chiroptical studies on supramolecular chirality of molecular aggregates.

    PubMed

    Sato, Hisako; Yajima, Tomoko; Yamagishi, Akihiko

    2015-10-01

    The attempts of applying chiroptical spectroscopy to supramolecular chirality are reviewed with a focus on vibrational circular dichroism (VCD). Examples were taken from gels, solids, and monolayers formed by low-molecular mass weight chiral gelators. Particular attention was paid to a group of gelators with perfluoroalkyl chains. The effects of the helical conformation of the perfluoroalkyl chains on the formation of chiral architectures are reported. It is described how the conformation of a chiral gelator was determined by comparing the experimental and theoretical VCD spectra together with a model proposed for the molecular aggregation in fibrils. The results demonstrate the potential utility of the chiroptical method in analyzing organized chiral aggregates. © 2015 Wiley Periodicals, Inc.

  8. Floquet Topological Order in Interacting Systems of Bosons and Fermions

    NASA Astrophysics Data System (ADS)

    Harper, Fenner; Roy, Rahul

    2017-03-01

    Periodically driven noninteracting systems may exhibit anomalous chiral edge modes, despite hosting bands with trivial topology. We find that these drives have surprising many-body analogs, corresponding to class A, which exhibit anomalous charge and information transport at the boundary. Drives of this form are applicable to generic systems of bosons, fermions, and spins, and may be characterized by the anomalous unitary operator that acts at the edge of an open system. We find that these operators are robust to all local perturbations and may be classified by a pair of coprime integers. This defines a notion of dynamical topological order that may be applied to general time-dependent systems, including many-body localized phases or time crystals.

  9. Higgs-like mechanism for spontaneous spacetime symmetry breaking

    NASA Astrophysics Data System (ADS)

    Nishimura, Kimihide

    2015-10-01

    The study of spontaneous breakdown of spacetime symmetries leads to the discovery of another type of Higgs mechanism operating in a chiral SU(2) model. Some of the Nambu-Goldstone vector mesons emergent from simultaneous violations of gauge and Lorentz symmetries are, in this case, absorbed by a left-handed doublet and endow one of the fermions with a right-handed state, while another part becomes emergent as photons. Accordingly, this mechanism allows a chiral fermion to acquire a mass, and it may enable the emergent theory to reproduce the electromagnetism equivalent to the QED sector in the standard theory. It is also mentioned that the "fermion-boson puzzle" known in the presence of a 't Hooft-Polyakov monopole does not exist in our theory.

  10. Topological chiral phonons in center-stacked bilayer triangle lattices

    NASA Astrophysics Data System (ADS)

    Xu, Xifang; Zhang, Wei; Wang, Jiaojiao; Zhang, Lifa

    2018-06-01

    Since chiral phonons were found in an asymmetric two-dimensional hexagonal lattice, there has been growing interest in the study of phonon chirality, which were experimentally verified very recently in monolayer tungsten diselenide (2018 Science 359 579). In this work, we find chiral phonons with nontrivial topology in center-stacked bilayer triangle lattices. At the Brillouin-zone corners, (), circularly polarized phonons and nonzero phonon Berry curvature are observed. Moreover, we find that the phonon chirality remain robust with changing sublattice mass ratio and interlayer coupling. The chiral phonons at the valleys are demonstrated in doubler-layer sodium chloride along the [1 1 1] direction. We believe that the findings on topological chiral phonons in triangle lattices will give guidance in the study of chiral phonons in real materials and promote the phononic applications.

  11. Clifford Algebra Implying Three Fermion Generations Revisited

    NASA Astrophysics Data System (ADS)

    Krolikowski, Wojciech

    2002-09-01

    The author's idea of algebraic compositeness of fundamental particles, allowing to understand the existence in Nature of three fermion generations, is revisited. It is based on two postulates. Primo, for all fundamental particles of matter the Dirac square-root procedure √ {p2} → {Γ }(N)p works, leading to a sequence N = 1,2,3, ... of Dirac-type equations, where four Dirac-type matrices {Γ }(N)μ are embedded into a Clifford algebra via a Jacobi definition introducing four ``centre-of-mass'' and (N-1)× four ``relative'' Dirac-type matrices. These define one ``centre-of-mass'' and (N-1) ``relative'' Dirac bispinor indices. Secundo, the ``centre-of-mass'' Dirac bispinor index is coupled to the Standard Model gauge fields, while (N-1) ``relative'' Dirac bispinor indices are all free indistinguishable physical objects obeying Fermi statistics along with the Pauli principle which requires the full antisymmetry with respect to ``relative'' Dirac indices. This allows only for three Dirac-type equations with N = 1,3,5 in the case of N odd, and two with N = 2,4 in the case of N even. The first of these results implies unavoidably the existence of three and only three generations of fundamental fermions, namely leptons and quarks, as labelled by the Standard Model signature. At the end, a comment is added on the possible shape of Dirac 3x3 mass matrices for four sorts of spin-1/2 fundamental fermions appearing in three generations. For charged leptons a prediction is mτ = 1776.80 MeV, when the input of experimental me and mμ is used.

  12. Ideal walking dynamics via a gauged NJL model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rantaharju, Jarno; Pica, Claudio; Sannino, Francesco

    According to the ideal walking technicolor paradigm, large mass anomalous dimensions arise in gauged Nambu–Jona-Lasinio (NJL) models when the four-fermion coupling is sufficiently strong to induce spontaneous symmetry breaking in an otherwise conformal gauge theory. Therefore, we study the SU(2) gauged NJL model with two adjoint fermions using lattice simulations. The model is in an infrared conformal phase at small NJL coupling while it displays a chirally broken phase at large NJL couplings. In the infrared conformal phase, we find that the mass anomalous dimension varies with the NJL coupling, reaching γm ~ 1 close to the chiral symmetry breakingmore » transition, de facto making the present model the first explicit realization of the ideal walking scenario.« less

  13. Ideal walking dynamics via a gauged NJL model

    DOE PAGES

    Rantaharju, Jarno; Pica, Claudio; Sannino, Francesco

    2017-07-25

    According to the ideal walking technicolor paradigm, large mass anomalous dimensions arise in gauged Nambu–Jona-Lasinio (NJL) models when the four-fermion coupling is sufficiently strong to induce spontaneous symmetry breaking in an otherwise conformal gauge theory. Therefore, we study the SU(2) gauged NJL model with two adjoint fermions using lattice simulations. The model is in an infrared conformal phase at small NJL coupling while it displays a chirally broken phase at large NJL couplings. In the infrared conformal phase, we find that the mass anomalous dimension varies with the NJL coupling, reaching γm ~ 1 close to the chiral symmetry breakingmore » transition, de facto making the present model the first explicit realization of the ideal walking scenario.« less

  14. Competitive chiral induction in a 2D molecular assembly: Intrinsic chirality versus coadsorber-induced chirality.

    PubMed

    Chen, Ting; Li, Shu-Ying; Wang, Dong; Wan, Li-Jun

    2017-11-01

    Noncovalently introducing stereogenic information is a promising approach to embed chirality in achiral molecular systems. However, the interplay of the noncovalently introduced chirality with the intrinsic chirality of molecules or molecular aggregations has rarely been addressed. We report a competitive chiral expression of the noncovalent interaction-mediated chirality induction and the intrinsic stereogenic center-controlled chirality induction in a two-dimensional (2D) molecular assembly at the liquid/solid interface. Two enantiomorphous honeycomb networks are formed by the coassembly of an achiral 5-(benzyloxy)isophthalic acid (BIC) derivative and 1-octanol at the liquid/solid interface. The preferential formation of the globally homochiral assembly can be achieved either by using the chiral analog of 1-octanol, ( S )-6-methyl-1-octanol, as a chiral coadsorber to induce chirality to the BIC assembly via noncovalent hydrogen bonding or by covalently linking a chiral center in the side chain of BIC. Both the chiral coadsorber and the intrinsically chiral BIC derivative can act as a chiral seeds to induce a preferred handedness in the assembly of the achiral BIC derivatives. Furthermore, the noncovalent interaction-mediated chirality induction can restrain or even overrule the manifestation of the intrinsic chirality of the BIC molecule and dominate the handedness of the 2D molecular coassembly. This study provides insight into the interplay of intrinsically chiral centers and external chiral coadsorbers in the chiral induction, transfer, and amplification processes of 2D molecular assembly.

  15. Competitive chiral induction in a 2D molecular assembly: Intrinsic chirality versus coadsorber-induced chirality

    PubMed Central

    Chen, Ting; Li, Shu-Ying; Wang, Dong; Wan, Li-Jun

    2017-01-01

    Noncovalently introducing stereogenic information is a promising approach to embed chirality in achiral molecular systems. However, the interplay of the noncovalently introduced chirality with the intrinsic chirality of molecules or molecular aggregations has rarely been addressed. We report a competitive chiral expression of the noncovalent interaction–mediated chirality induction and the intrinsic stereogenic center–controlled chirality induction in a two-dimensional (2D) molecular assembly at the liquid/solid interface. Two enantiomorphous honeycomb networks are formed by the coassembly of an achiral 5-(benzyloxy)isophthalic acid (BIC) derivative and 1-octanol at the liquid/solid interface. The preferential formation of the globally homochiral assembly can be achieved either by using the chiral analog of 1-octanol, (S)-6-methyl-1-octanol, as a chiral coadsorber to induce chirality to the BIC assembly via noncovalent hydrogen bonding or by covalently linking a chiral center in the side chain of BIC. Both the chiral coadsorber and the intrinsically chiral BIC derivative can act as a chiral seeds to induce a preferred handedness in the assembly of the achiral BIC derivatives. Furthermore, the noncovalent interaction–mediated chirality induction can restrain or even overrule the manifestation of the intrinsic chirality of the BIC molecule and dominate the handedness of the 2D molecular coassembly. This study provides insight into the interplay of intrinsically chiral centers and external chiral coadsorbers in the chiral induction, transfer, and amplification processes of 2D molecular assembly. PMID:29119137

  16. Enantioselective column coupled electrophoresis employing large bore capillaries hyphenated with tandem mass spectrometry for ultra-trace determination of chiral compounds in complex real samples.

    PubMed

    Piešťanský, Juraj; Maráková, Katarína; Kovaľ, Marián; Havránek, Emil; Mikuš, Peter

    2015-12-01

    A new multidimensional analytical approach for the ultra-trace determination of target chiral compounds in unpretreated complex real samples was developed in this work. The proposed analytical system provided high orthogonality due to on-line combination of three different methods (separation mechanisms), i.e. (1) isotachophoresis (ITP), (2) chiral capillary zone electrophoresis (chiral CZE), and (3) triple quadrupole mass spectrometry (QqQ MS). The ITP step, performed in a large bore capillary (800 μm), was utilized for the effective sample pretreatment (preconcentration and matrix clean-up) in a large injection volume (1-10 μL) enabling to obtain as low as ca. 80 pg/mL limits of detection for the target enantiomers in urine matrices. In the chiral CZE step, the different chiral selectors (neutral, ionizable, and permanently charged cyclodextrins) and buffer systems were tested in terms of enantioselectivity and influence on the MS detection response. The performance parameters of the optimized ITP - chiral CZE-QqQ MS method were evaluated according to the FDA guidance for bioanalytical method validation. Successful validation and application (enantioselective monitoring of renally eliminated pheniramine and its metabolite in human urine) highlighted great potential of this chiral approach in advanced enantioselective biomedical applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Chiral Gold Nanoclusters: Atomic Level Origins of Chirality.

    PubMed

    Zeng, Chenjie; Jin, Rongchao

    2017-08-04

    Chiral nanomaterials have received wide interest in many areas, but the exact origin of chirality at the atomic level remains elusive in many cases. With recent significant progress in atomically precise gold nanoclusters (e.g., thiolate-protected Au n (SR) m ), several origins of chirality have been unveiled based upon atomic structures determined by using single-crystal X-ray crystallography. The reported chiral Au n (SR) m structures explicitly reveal a predominant origin of chirality that arises from the Au-S chiral patterns at the metal-ligand interface, as opposed to the chiral arrangement of metal atoms in the inner core (i.e. kernel). In addition, chirality can also be introduced by a chiral ligand, manifested in the circular dichroism response from metal-based electronic transitions other than the ligand's own transition(s). Lastly, the chiral arrangement of carbon tails of the ligands has also been discovered in a very recent work on chiral Au 133 (SR) 52 and Au 246 (SR) 80 nanoclusters. Overall, the origins of chirality discovered in Au n (SR) m nanoclusters may provide models for the understanding of chirality origins in other types of nanomaterials and also constitute the basis for the development of various applications of chiral nanoparticles. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Monotop signature from a fermionic top partner

    NASA Astrophysics Data System (ADS)

    Gonçalves, Dorival; Kong, Kyoungchul; Sakurai, Kazuki; Takeuchi, Michihisa

    2018-01-01

    We investigate monotop signatures arising from phenomenological models of fermionic top partners, which are degenerate in mass and decay into a bosonic dark matter candidate, either spin 0 or spin 1. Such a model provides a monotop signature as a smoking gun, while conventional searches with t t ¯ + missing transverse momentum are limited. Two such scenarios, (i) a phenomenological third generation extradimensional model with excited top and electroweak sectors, and (ii) a model where only a top partner and a dark matter particle are added to the standard model, are studied in the degenerate mass regime. We find that in the case of extra dimension a number of different processes give rise to effectively the same monotop final state, and a great gain can be obtained in the sensitivity for this channel. We show that the monotop search can explore top-partner masses up to 630 and 300 GeV for the third generation extradimensional model and the minimal fermionic top-partner model, respectively, at the high luminosity LHC.

  19. Distinct evolutions of Weyl fermion quasiparticles and Fermi arcs with bulk band topology in Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Xu, Nan; Autes, Gabriel; Matt, Christian; Lv, Baiqing; Bisti, Federico; Strocov, Vladimir; Gawryluk, Dariusz; Pomjakushina, Ekaterina; Conder, Kazimierz; Plumb, Nicholas; Radovic, Milan; Qian, Tian; Yazyev, Oleg; Mesot, Joel; Ding, Hong; Shi, Ming

    By performing ARPES and first-principle calculations, we demonstrate that Weyl fermions quasiparticles in bulk and Fermi arc on surface show distinct evolutions with the bulk band topology in transition-metal monophosphides. While Weyl fermion quasiparticles exist only when the chemical potential is located between two saddle points of the Weyl cone features, the Fermi arc states extend in a larger energy scale and are robust across the bulk Lifshitz transitions associated with the recombination of two non-trivial Fermi surfaces enclosing one Weyl point into a single trivial Fermi surface enclosing two Weyl points of opposite chirality. Therefore, in some systems (NbP), Fermi arc states are preserved even if Weyl fermion quasiparticles are absent in the bulk. Our findings not only provide insight into the relationship between the exotic physical phenomena and the intrinsic bulk band topology in Weyl semimetals, but also resolve the apparent puzzle of the different magneto-transport properties observed in TaAs, TaP and NbP, where the Fermi arc states are similar. The Sino-Swiss Science and Technology Cooperation (No. IZLCZ2138954), NCCR-MARVEL funded by the Swiss National Science Foundation.

  20. Singlet-triplet fermionic dark matter and LHC phenomenology

    NASA Astrophysics Data System (ADS)

    Choubey, Sandhya; Khan, Sarif; Mitra, Manimala; Mondal, Subhadeep

    2018-04-01

    It is well known that for the pure standard model triplet fermionic WIMP-type dark matter (DM), the relic density is satisfied around 2 TeV. For such a heavy mass particle, the production cross-section at 13 TeV run of LHC will be very small. Extending the model further with a singlet fermion and a triplet scalar, DM relic density can be satisfied for even much lower masses. The lower mass DM can be copiously produced at LHC and hence the model can be tested at collider. For the present model we have studied the multi jet (≥ 2 j) + missing energy ([InlineEquation not available: see fulltext.]) signal and show that this can be detected in the near future of the LHC 13 TeV run. We also predict that the present model is testable by the earth based DM direct detection experiments like Xenon-1T and in future by Darwin.

  1. Chiral Analysis by Tandem Mass Spectrometry Using the Kinetic Method, by Polarimetry, and by [Superscript 1]H NMR Spectroscopy

    ERIC Educational Resources Information Center

    Fedick, Patrick W.; Bain, Ryan M.; Bain, Kinsey; Cooks, R. Graham

    2017-01-01

    The goal of this laboratory exercise was for students to understand the concept of chirality and how enantiomeric excess (ee) is experimentally determined using the analysis of ibuprofen as an example. Students determined the enantiomeric excess of the analyte by three different instrumental methods: mass spectrometry, nuclear magnetic resonance…

  2. Covariant and 3 + 1 Equations for Dynamo-Chiral General Relativistic Magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Del Zanna, L.; Bucciantini, N.

    2018-06-01

    The exponential amplification of initial seed magnetic fields in relativistic plasmas is a very important topic in astrophysics, from the conditions in the early Universe to the interior of neutron stars. While dynamo action in a turbulent plasma is often invoked, in the last years a novel mechanism of quantum origin has gained increasingly more attention, namely the Chiral Magnetic Effect (CME). This has been recognized in semi-metals and it is most likely at work in the quark-gluon plasma formed in heavy-ion collision experiments, where the highest magnetic fields in nature, up to B ˜ 1018 G, are produced. This effect is expected to survive even at large hydrodynamical/MHD scales and it is based on the chiral anomaly due to an imbalance between left- and right-handed relativistic fermions in the constituent plasma. Such imbalance leads to an electric current parallel to an external magnetic field, which is precisely the same mechanism of an α-dynamo action in classical MHD. Here we extend the close parallelism between the chiral and the dynamo effects to relativistic plasmas and we propose a unified, fully covariant formulation of the generalized Ohm's law. Moreover, we derive for the first time the 3 + 1 general relativistic MHD equations for a chiral plasma both in flat and curved spacetimes, in view of numerical investigation of the CME in compact objects, especially magnetars, or of the interplay among the non-ideal magnetic effects of dynamo, the CME and reconnection.

  3. The one step fermionic ladder

    NASA Astrophysics Data System (ADS)

    Das, Joy Prakash; Setlur, Girish S.

    2017-10-01

    The one step fermionic ladder refers to two parallel Luttinger Liquids (poles of the ladder) placed such that there is a finite probability of electrons hopping between the two poles at a pair of opposing points along each of the poles. The many-body Green function for such a system is calculated in presence of forward scattering interactions using the powerful non-chiral bosonization technique (NCBT). This technique is based on a non-standard harmonic analysis of the rapidly varying parts of the density fields appropriate for the study of strongly inhomogeneous ladder systems. The closed analytical expression for the correlation function obtained from NCBT is nothing but the series involving the RPA (Random Phase Approximation) diagrams in powers of the forward scattering coupling strength resummed to include only the most singular terms with the source of inhomogeneities treated exactly. Finally the correlation functions are used to study physical phenomena such as Friedel oscillations and the conductance of such systems with the potential difference applied across various ends.

  4. The Kaon B-parameter in mixed action chiral perturbation theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aubin, C.; /Columbia U.; Laiho, Jack

    2006-09-01

    We calculate the kaon B-parameter, B{sub K}, in chiral perturbation theory for a partially quenched, mixed action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We find that the resulting expression is similar to that in the continuum, and in fact has only two additional unknown parameters. At one-loop order, taste-symmetry violations in the staggered sea sector only contribute to flavor-disconnected diagrams by generating an {Omicron}(a{sup 2}) shift to the masses of taste-singlet sea-sea mesons. Lattice discretization errors also give rise to an analytic term which shifts the tree-level value of B{sub K} by an amount of {Omicron}(a{sup 2}).more » This term, however, is not strictly due to taste-breaking, and is therefore also present in the expression for B{sub K} for pure G-W lattice fermions. We also present a numerical study of the mixed B{sub K} expression in order to demonstrate that both discretization errors and finite volume effects are small and under control on the MILC improved staggered lattices.« less

  5. Cubic Dirac fermions in quasi-one-dimensional transition-metal chalcogenide semimetals immune to Peierls distortion

    NASA Astrophysics Data System (ADS)

    Liu, Qihang; Zunger, Alex

    A Cubic Dirac Fermion in condensed-matter physics refers to a band crossing in periodic solids that has 4-fold degeneracy with cubic dispersions in certain directions. Such a crystalline symmetry induced fermion is composed of 6 Weyl fermions where 3 have left-handed and 3 have right-handed chirality, and constitutes one of the ``new fermions'' that have no counterpart in high-energy physics. However, no prediction has yet pointed to a plausible example of a material candidate hosting such a cubically-dispersed Dirac semimetal (CDSM). Here we establish the design principles for CDSM finding that only 2 out of 230 space groups possess the required symmetry elements. Adding the required band occupancy criteria, we conduct a material search using density functional band theory identifying a group of quasi-one-dimensional molybdenum chalcogenide compounds A(MoX)3 (A = Na, K, Rb, In, Tl; X = S, Se, Te) with space group P63/m as ideal CDSM candidates. Studying the stability of the A(MoX)3 family towards a Peierls distortion reveals a few candidates such as Rb(MoTe)3 and Tl(MoTe)3 that are resilliant to Peierls distortion, thus retaining the metallic character. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division under Grant No. DE-FG02-13ER46959 to University of Colorado, Boulder.

  6. Topological phase transitions and chiral inelastic transport induced by the squeezing of light

    PubMed Central

    Peano, Vittorio; Houde, Martin; Brendel, Christian; Marquardt, Florian; Clerk, Aashish A.

    2016-01-01

    There is enormous interest in engineering topological photonic systems. Despite intense activity, most works on topological photonic states (and more generally bosonic states) amount in the end to replicating a well-known fermionic single-particle Hamiltonian. Here we show how the squeezing of light can lead to the formation of qualitatively new kinds of topological states. Such states are characterized by non-trivial Chern numbers, and exhibit protected edge modes, which give rise to chiral elastic and inelastic photon transport. These topological bosonic states are not equivalent to their fermionic (topological superconductor) counterparts and, in addition, cannot be mapped by a local transformation onto topological states found in particle-conserving models. They thus represent a new type of topological system. We study this physics in detail in the case of a kagome lattice model, and discuss possible realizations using nonlinear photonic crystals or superconducting circuits. PMID:26931620

  7. Topological phase transitions and chiral inelastic transport induced by the squeezing of light

    NASA Astrophysics Data System (ADS)

    Peano, Vittorio; Houde, Martin; Brendel, Christian; Marquardt, Florian; Clerk, Aashish A.

    2016-03-01

    There is enormous interest in engineering topological photonic systems. Despite intense activity, most works on topological photonic states (and more generally bosonic states) amount in the end to replicating a well-known fermionic single-particle Hamiltonian. Here we show how the squeezing of light can lead to the formation of qualitatively new kinds of topological states. Such states are characterized by non-trivial Chern numbers, and exhibit protected edge modes, which give rise to chiral elastic and inelastic photon transport. These topological bosonic states are not equivalent to their fermionic (topological superconductor) counterparts and, in addition, cannot be mapped by a local transformation onto topological states found in particle-conserving models. They thus represent a new type of topological system. We study this physics in detail in the case of a kagome lattice model, and discuss possible realizations using nonlinear photonic crystals or superconducting circuits.

  8. Emission of fermions in little string theory

    NASA Astrophysics Data System (ADS)

    Lorente-Espín, Oscar

    2013-03-01

    It is well known that little string theory (LST) black holes radiate a purely thermal spectrum of scalar particles. This theory lives in a Hagedorn phase with a fixed Hagedorn temperature that does not depend on its mass. Therefore, the theory keeps a thermal profile even taking into account self-gravitating effects and the backreaction of the metric. This has implications concerning the information loss paradox; one would not be able to recover any information from the LST black hole since the emission of scalar particles is totally uncorrelated. Several studies of the emission spectrum in LST concern scalar fields; it is our aim in this work to extend the study to the emission of fermions in order to verify that the most relevant conclusion for the scalar field remains valid for the fermion fields. Thus, we have calculated the emission probability, the flux, and also the greybody factor corresponding to a fermion field in LST background.

  9. Gelation induced supramolecular chirality: chirality transfer, amplification and application.

    PubMed

    Duan, Pengfei; Cao, Hai; Zhang, Li; Liu, Minghua

    2014-08-14

    Supramolecular chirality defines chirality at the supramolecular level, and is generated from the spatial arrangement of component molecules assembling through non-covalent interactions such as hydrogen bonding, van der Waals interactions, π-π stacking, hydrophobic interactions and so on. During the formation of low molecular weight gels (LMWGs), one kind of fascinating soft material, one frequently encounters the phenomenon of chirality as well as chiral nanostructures, either from chiral gelators or even achiral gelators. A view of gelation-induced supramolecular chirality will be very helpful to understand the self-assembly process of the gelator molecules as well as the chiral structures, the regulation of the chirality in the gels and the development of the "smart" chiral materials such as chiroptical devices, catalysts and chiral sensors. It necessitates fundamental understanding of chirality transfer and amplification in these supramolecular systems. In this review, recent progress in gelation-induced supramolecular chirality is discussed.

  10. Analysis of Chiral Carboxylic Acids in Meteorites

    NASA Technical Reports Server (NTRS)

    Burton, A. S.; Elsila, J. E.; Hein, J. E.; Aponte, J. C.; Parker, E. T.; Glavin, D. P.; Dworkin, J. P.

    2015-01-01

    Homochirality of amino acids in proteins and sugars in DNA and RNA is a critical feature of life on Earth. In the absence of a chiral driving force, however, reactions leading to the synthesis of amino acids and sugars result in racemic mixtures. It is currently unknown whether homochirality was necessary for the origins of life or if it was a product of early life. The observation of enantiomeric excesses of certain amino acids of extraterrestrial origins in meteorites provides evidence to support the hypothesis that there was a mechanism for the preferential synthesis or destruction of a particular amino acid enantiomer [e.g., 1-3]. The cause of the observed chiral excesses is un-clear, although at least in the case of the amino acid isovaline, the degree of aqueous alteration that occurred on the meteorite parent body is correlated to the isovaline L-enantiomeric excess [3, 4]. This suggests that chiral symmetry is broken and/or amplified within the meteorite parent bodies. Besides amino acids, there have been only a few reports of other meteoritic compounds found in enantiomeric excess: sugars and sugar acids [5, 6] and the hydroxy acid lactic acid [7]. Determining whether or not additional types of molecules in meteorites are also present in enantiomeric excesses of extraterrestrial information will provide insights into mechanisms for breaking chiral symmetry. Though the previous measurements (e.g., enantiomeric composition of lactic acid [7], and chiral carboxylic acids [8]) were made by gas chromatography-mass spectrometry, the potential for increased sensitivity of liquid chromatography-mass spectrometry (LC-MS) analyses is important because for many meteorite samples, only small sample masses are available for study. Furthermore, at least in the case of amino acids, many of the largest amino acid enantiomeric excesses were observed in samples that contained lower abundances (tens of ppb) of a given amino acid enantiomer. In the present work, we describe

  11. Surmounting the sign problem in nonrelativistic calculations: A case study with mass-imbalanced fermions

    NASA Astrophysics Data System (ADS)

    Rammelmüller, Lukas; Porter, William J.; Drut, Joaquín E.; Braun, Jens

    2017-11-01

    The calculation of the ground state and thermodynamics of mass-imbalanced Fermi systems is a challenging many-body problem. Even in one spatial dimension, analytic solutions are limited to special configurations and numerical progress with standard Monte Carlo approaches is hindered by the sign problem. The focus of the present work is on the further development of methods to study imbalanced systems in a fully nonperturbative fashion. We report our calculations of the ground-state energy of mass-imbalanced fermions using two different approaches which are also very popular in the context of the theory of the strong interaction (quantum chromodynamics, QCD): (a) the hybrid Monte Carlo algorithm with imaginary mass imbalance, followed by an analytic continuation to the real axis; and (b) the complex Langevin algorithm. We cover a range of on-site interaction strengths that includes strongly attractive as well as strongly repulsive cases which we verify with nonperturbative renormalization group methods and perturbation theory. Our findings indicate that, for strong repulsive couplings, the energy starts to flatten out, implying interesting consequences for short-range and high-frequency correlation functions. Overall, our results clearly indicate that the complex Langevin approach is very versatile and works very well for imbalanced Fermi gases with both attractive and repulsive interactions.

  12. Proposal for chiral-boson search at LHC via their unique new signature

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chizhov, M. V.; Bednyakov, V. A.; Budagov, J. A.

    The resonance production of new chiral spin-1 bosons and their detection through the Drell-Yan process at the CERN LHC is considered. Quantitative evaluations of various differential cross sections of the chiral-boson production are made within the CalcHEP package. The new neutral chiral bosons can be observed as a Breit-Wigner resonance peak in the invariant-dilepton-mass distribution, as usual. However, unique new signatures of the chiral bosons exist. First, there is no Jacobian peak in the lepton transverse-momentum distribution. Second, the lepton angular distribution in the Collins-Soper frame for the high on-peak invariant masses of the lepton pairs has a peculiar 'swallowtail'more » shape.« less

  13. Chiral Separations

    NASA Astrophysics Data System (ADS)

    Stalcup, A. M.

    2010-07-01

    The main goal of this review is to provide a brief overview of chiral separations to researchers who are versed in the area of analytical separations but unfamiliar with chiral separations. To researchers who are not familiar with this area, there is currently a bewildering array of commercially available chiral columns, chiral derivatizing reagents, and chiral selectors for approaches that span the range of analytical separation platforms (e.g., high-performance liquid chromatography, gas chromatography, supercritical-fluid chromatography, and capillary electrophoresis). This review begins with a brief discussion of chirality before examining the general strategies and commonalities among all of the chiral separation techniques. Rather than exhaustively listing all the chiral selectors and applications, this review highlights significant issues and differences between chiral and achiral separations, providing salient examples from specific classes of chiral selectors where appropriate.

  14. Evidence for Δ(2200)7/2 $-$ from photoproduction and consequence for chiral-symmetry restoration at high mass

    DOE PAGES

    Anisovich, A. V.; Burkert, Volker D.; Hartmann, J.; ...

    2016-12-12

    We report a partial-wave analysis of new data on the double-polarization variable E for the reactions γp→π +n and γp→π 0p and of further data published earlier. The analysis within the Bonn–Gatchina (BnGa) formalism reveals evidence for a poorly known baryon resonance, the one-star Δ(2200)7/2 $-$. This is the lowest-mass Δ* resonance with spin-parity J P=7/2 $-$. Its mass is significantly higher than the mass of its parity partner Δ(1950)7/2 + which is the lowest-mass Δ* resonance with spin-parity J P=7/2 +. It has been suggested that chiral symmetry might be restored in the high-mass region of hadron excitations, andmore » that these two resonances should be degenerate in mass. Lastly, our findings are in conflict with this prediction.« less

  15. Colossal thermomagnetic response in chiral d-wave superconductor URu2Si2

    NASA Astrophysics Data System (ADS)

    Matsuda, Yuji

    The heavy-fermion compound URu2Si2 exhibits unconventional superconductivity at Tc = 1.45 K deep inside the so-called hidden order phase. An intriguing aspect is that this system has been suggested to be a candidate of a chiral d-wave superconductor, and possible Weyl-type topological superconducting states have been discussed recently. Here we report on the observation of a highly unusual Nernst signal due to the superconducting fluctuations above Tc. The Nernst coefficient is anomalously enhanced (by a factor of ~106) as compared with the theoretically expected value of the Gaussian fluctuations. This colossal Nernst effect intimately reflects the highly unusual superconducting state of URu2Si2. The results invoke possible chiral or Berry-phase fluctuations associated with the broken time-reversal symmetry of the superconducting order parameter. In collaboration with T. Yamashita, Y. Shimoyama, H. Sumiyoshi (Kyoto), S. Fujimoto (Osaka), T. Shibauchi (Tokyo), Y. Haga (JAEA), T. D. Matsuda (TMU) , Y. Onuki (Ryukyus), A. Levchenko (Wisconsin-Madison).

  16. Involution Requirement on a Boundary Makes Massless Fermions Compactified on a Finite Flat Disk Mass Protected

    NASA Astrophysics Data System (ADS)

    Mankoč Borštnik, N. S.; Nielsen, H. B.

    2006-12-01

    The genuine Kaluza-Klein-like theories--with no fields in addition to gravity--have difficulties with the existence of massless spinors after the compactification of some space dimensions \\cite{witten}. We proposed (Phys. Lett. B 633 (2006)771) such a boundary condition for spinors in 1+5 compactified on a flat disk that ensures masslessness of spinors in d=1+3 as well as their chiral coupling to the corresponding background gauge field (which solves equations of motion for a free field linear in the Riemann curvature). In this paper we study the same toy model: M^{(1+3)} x M^{(2)}, looking this time for an involution which transforms a space of solutions of Weyl equations in d=1+5 from the outside of the flat disk in x^5 and x^6 into its inside, allowing massless spinor of only one handedness--and accordingly assures mass protection--and of one charge--1/2--and infinitely many massive spinors of the same charge, chirally coupled to the corresponding background gauge field. We reformulate the operator of momentum so that it is Hermitean on the vector space of spinor states obeying the involution boundary condition.

  17. Scales of mass generation for quarks, leptons, and majorana neutrinos.

    PubMed

    Dicus, Duane A; He, Hong-Jian

    2005-06-10

    We study 2-->n inelastic fermion-(anti)fermion scattering into multiple longitudinal weak gauge bosons and derive universal upper bounds on the scales of fermion mass generation by imposing unitarity of the S matrix. We place new upper limits on the scales of fermion mass generation, independent of the electroweak symmetry breaking scale. Strikingly, we find that the strongest 2-->n limits fall in a narrow range, 3-170 TeV (with n=2-24), depending on the observed fermion masses.

  18. Dark matter direct detection of a fermionic singlet at one loop

    NASA Astrophysics Data System (ADS)

    Herrero-García, Juan; Molinaro, Emiliano; Schmidt, Michael A.

    2018-06-01

    The strong direct detection limits could be pointing to dark matter - nucleus scattering at loop level. We study in detail the prototype example of an electroweak singlet (Dirac or Majorana) dark matter fermion coupled to an extended dark sector, which is composed of a new fermion and a new scalar. Given the strong limits on colored particles from direct and indirect searches we assume that the fields of the new dark sector are color singlets. We outline the possible simplified models, including the well-motivated cases in which the extra scalar or fermion is a Standard Model particle, as well as the possible connection to neutrino masses. We compute the contributions to direct detection from the photon, the Z and the Higgs penguins for arbitrary quantum numbers of the dark sector. Furthermore, we derive compact expressions in certain limits, i.e., when all new particles are heavier than the dark matter mass and when the fermion running in the loop is light, like a Standard Model lepton. We study in detail the predicted direct detection rate and how current and future direct detection limits constrain the model parameters. In case dark matter couples directly to Standard Model leptons we find an interesting interplay between lepton flavor violation, direct detection and the observed relic abundance.

  19. Quantum oscillations in the heavy-fermion compound YbPtBi

    DOE PAGES

    Mun, E.; Bud'ko, S. L.; Lee, Y.; ...

    2015-08-01

    We present quantum oscillations observed in the heavy-fermion compound YbPtBi in magnetic fields far beyond its field-tuned, quantum critical point. Quantum oscillations are observed in magnetic fields as low as 60 kOe at 60 mK and up to temperatures as high as 3 K, which confirms the very high quality of the samples as well as the small effective mass of the conduction carriers far from the quantum critical point. Although the electronic specific heat coefficient of YbPtBi reaches ~7.4 J/molK 2 in zero field, which is one of the highest effective mass values among heavy-fermion systems, we suppress itmore » quickly by an applied magnetic field. The quantum oscillations were used to extract the quasiparticle effective masses of the order of the bare electron mass, which is consistent with the behavior observed in specific heat measurements. Furthermore, such small effective masses at high fields can be understood by considering the suppression of Kondo screening.« less

  20. Critical fermion density for restoring spontaneously broken symmetry

    NASA Astrophysics Data System (ADS)

    Kleinert, Hagen; Xue, She-Sheng

    2015-07-01

    We show how the phenomenon of spontaneous symmetry breakdown is affected by the presence of a sea of fermions in the system. When its density exceeds a critical value, the broken symmetry can be restored. We calculate the critical value and discuss the consequences for three different physical systems: First, for the Standard Model (SM) of particle physics, where the spontaneous symmetry breakdown leads to nonzero masses of intermediate gauge bosons and fermions. The symmetry restoration will greatly enhance various processes with dramatic consequences for the early universe. Second, for the Gell-Mann-Lévy σ-model of nuclear physics, where the symmetry breakdown gives rise to the nucleon and meson masses. The symmetry restoration may have important consequences for formation or collapse of stellar cores. Third, for the superconductive phase of condensed-matter, where the BCS condensate at low-temperature may be destroyed by a too large electron density.

  1. Phase structure of NJL model with weak renormalization group

    NASA Astrophysics Data System (ADS)

    Aoki, Ken-Ichi; Kumamoto, Shin-Ichiro; Yamada, Masatoshi

    2018-06-01

    We analyze the chiral phase structure of the Nambu-Jona-Lasinio model at finite temperature and density by using the functional renormalization group (FRG). The renormalization group (RG) equation for the fermionic effective potential V (σ ; t) is given as a partial differential equation, where σ : = ψ bar ψ and t is a dimensionless RG scale. When the dynamical chiral symmetry breaking (DχSB) occurs at a certain scale tc, V (σ ; t) has singularities originated from the phase transitions, and then one cannot follow RG flows after tc. In this study, we introduce the weak solution method to the RG equation in order to follow the RG flows after the DχSB and to evaluate the dynamical mass and the chiral condensate in low energy scales. It is shown that the weak solution of the RG equation correctly captures vacuum structures and critical phenomena within the pure fermionic system. We show the chiral phase diagram on temperature, chemical potential and the four-Fermi coupling constant.

  2. Chiral density wave versus pion condensation at finite density and zero temperature

    NASA Astrophysics Data System (ADS)

    Andersen, Jens O.; Kneschke, Patrick

    2018-04-01

    The quark-meson model is often used as a low-energy effective model for QCD to study the chiral transition at finite temperature T , baryon chemical potential μB , and isospin chemical potential μI . We determine the parameters of the model by matching the meson and quark masses, as well as the pion decay constant to their physical values using the on shell (OS) and modified minimal subtraction (MS ¯ ) schemes. In this paper, the existence of different phases at zero temperature is studied. In particular, we investigate the competition between an inhomogeneous chiral condensate and a homogeneous pion condensate. For the inhomogeneity, we use a chiral-density wave ansatz. For a sigma mass of 600 MeV, we find that an inhomogeneous chiral condensate exists only for pion masses below approximately 37 MeV. We also show that due to our parameter fixing, the onset of pion condensation takes place exactly at μIc=1/2 mπ in accordance with exact results.

  3. Determination of the chiral condensate from (2+1)-flavor lattice QCD.

    PubMed

    Fukaya, H; Aoki, S; Hashimoto, S; Kaneko, T; Noaki, J; Onogi, T; Yamada, N

    2010-03-26

    We perform a precise calculation of the chiral condensate in QCD using lattice QCD with 2+1 flavors of dynamical overlap quarks. Up and down quark masses cover a range between 3 and 100 MeV on a 16{3}x48 lattice at a lattice spacing approximately 0.11 fm. At the lightest sea quark mass, the finite volume system on the lattice is in the regime. By matching the low-lying eigenvalue spectrum of the Dirac operator with the prediction of chiral perturbation theory at the next-to-leading order, we determine the chiral condensate in (2+1)-flavor QCD with strange quark mass fixed at its physical value as Sigma;{MS[over ]}(2 GeV)=[242(04)(+19/-18) MeV]{3} where the errors are statistical and systematic, respectively.

  4. Probing the fermionic Higgs portal at lepton colliders

    DOE PAGES

    Fedderke, Michael A.; Lin, Tongyan; Wang, Lian -Tao

    2016-04-26

    Here, we study the sensitivity of future electron-positron colliders to UV completions of the fermionic Higgs portal operator H †Hχ¯χ. Measurements of precision electroweak S and T parameters and the e +e – → Zh cross-section at the CEPC, FCC-ee, and ILC are considered. The scalar completion of the fermionic Higgs portal is closely related to the scalar Higgs portal, and we summarize existing results. We devote the bulk of our analysis to a singlet-doublet fermion completion. Assuming the doublet is sufficiently heavy, we construct the effective field theory (EFT) at dimension-6 in order to compute contributions to the observables.more » We also provide full one-loop results for S and T in the general mass parameter space. In both completions, future precision measurements can probe the new states at the (multi-)TeV scale, beyond the direct reach of the LHC.« less

  5. Probing the fermionic Higgs portal at lepton colliders

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fedderke, Michael A.; Lin, Tongyan; Wang, Lian -Tao

    Here, we study the sensitivity of future electron-positron colliders to UV completions of the fermionic Higgs portal operator H †Hχ¯χ. Measurements of precision electroweak S and T parameters and the e +e – → Zh cross-section at the CEPC, FCC-ee, and ILC are considered. The scalar completion of the fermionic Higgs portal is closely related to the scalar Higgs portal, and we summarize existing results. We devote the bulk of our analysis to a singlet-doublet fermion completion. Assuming the doublet is sufficiently heavy, we construct the effective field theory (EFT) at dimension-6 in order to compute contributions to the observables.more » We also provide full one-loop results for S and T in the general mass parameter space. In both completions, future precision measurements can probe the new states at the (multi-)TeV scale, beyond the direct reach of the LHC.« less

  6. Two-Dimensional Collective Hamiltonian for Chiral and Wobbling Modes

    DOE PAGES

    Chen, Q. B.; Zhang, S. Q.; Zhao, P. W.; ...

    2016-10-03

    Here, a two-dimensional collective Hamiltonian (2DCH) on both azimuth and polar motions in triaxial nuclei is proposed to investigate the chiral and wobbling modes. In the 2DCH, the collective potential and the mass parameters are determined from three-dimensional tilted axis cranking (TAC) calculations. The broken chiral and signature symmetries in the TAC solutions are restored by the 2DCH. The validity of the 2DCH is illustrated with a triaxial rotor (γ= -30°) coupling to one h 11/2 proton particle and one h 11/2 neutron hole. By diagonalizing the 2DCH, the angular momenta and energy spectra are obtained. These results agree withmore » the exact solutions of the particle rotor model (PRM) at high rotational frequencies. However, at low frequencies, the energies given by the 2DCH are larger than those by the PRM due to the underestimation of the mass parameters. In addition, with increasing angular momentum, the transitions from the chiral vibration to chiral rotation and further to longitudinal wobbling motion have been presented in the 2DCH.« less

  7. Two-Dimensional Collective Hamiltonian for Chiral and Wobbling Modes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Q. B.; Zhang, S. Q.; Zhao, P. W.

    Here, a two-dimensional collective Hamiltonian (2DCH) on both azimuth and polar motions in triaxial nuclei is proposed to investigate the chiral and wobbling modes. In the 2DCH, the collective potential and the mass parameters are determined from three-dimensional tilted axis cranking (TAC) calculations. The broken chiral and signature symmetries in the TAC solutions are restored by the 2DCH. The validity of the 2DCH is illustrated with a triaxial rotor (γ= -30°) coupling to one h 11/2 proton particle and one h 11/2 neutron hole. By diagonalizing the 2DCH, the angular momenta and energy spectra are obtained. These results agree withmore » the exact solutions of the particle rotor model (PRM) at high rotational frequencies. However, at low frequencies, the energies given by the 2DCH are larger than those by the PRM due to the underestimation of the mass parameters. In addition, with increasing angular momentum, the transitions from the chiral vibration to chiral rotation and further to longitudinal wobbling motion have been presented in the 2DCH.« less

  8. Chirality Differentiation by Diffusion in Chiral Nematic Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Jiang, Jinghua; Yang, Deng-Ke

    2017-01-01

    Chirality is of great importance in the living world. It helps differentiate biochemical reactions such as those that take place during digestion. It may also help differentiate physical processes such as diffusion. Aiming to study the latter effect, we investigate the diffusion of guest chiral molecules in chiral nematic (cholesteric) liquid-crystal hosts. We discover that the diffusion dramatically depends on the handedness of the guest and host molecules and the chiral differentiation is greatly enhanced by the proper alignment of the liquid-crystal host. The diffusion of a guest chiral molecule in a chiral host with the same handedness is much faster than in a chiral host with opposite handedness. We also observe that the differentiation of chirality depends on the diffusion direction with respect to the twisting direction (helical axis). These results might be important in understanding effects of chirality on physical processes that take place in biological organisms. In addition, this effect could be utilized for enantiomer separation.

  9. Unification with vector-like fermions and signals at LHC

    NASA Astrophysics Data System (ADS)

    Bhattacherjee, Biplob; Byakti, Pritibhajan; Kushwaha, Ashwani; Vempati, Sudhir K.

    2018-05-01

    We look for minimal extensions of Standard Model with vector like fermions leading to precision unification of gauge couplings. Constraints from proton decay, Higgs stability and perturbativity are considered. The simplest models contain several copies of vector fermions in two different (incomplete) representations. Some of these models encompass Type III seesaw mechanism for neutrino masses whereas some others have a dark matter candidate. In all the models, at least one of the candidates has non-trivial representation under SU(3)color. In the limit of vanishing Yukawa couplings, new QCD bound states are formed, which can be probed at LHC. The present limits based on results from 13 TeV already probe these particles for masses around a TeV. Similar models can be constructed with three or four vector representations, examples of which are presented.

  10. Chiral signs of TPPS co-assemblies with chiral gelators: role of molecular and supramolecular chirality.

    PubMed

    Wang, Qiuling; Zhang, Li; Yang, Dong; Li, Tiesheng; Liu, Minghua

    2016-10-13

    A dianionic tetrakis(4-sulfonatophenyl)porphyrin (TPPS) self-assembled into J-aggregates when it co-assembled with a chiral cationic amphiphile via supramolecular gelation. The chiral signs of TPPS J aggregates followed the supramolecular chirality of amphiphilic assemblies rather than the molecular chirality of the amphiphile.

  11. Light-Nuclei Spectra from Chiral Dynamics

    NASA Astrophysics Data System (ADS)

    Piarulli, M.; Baroni, A.; Girlanda, L.; Kievsky, A.; Lovato, A.; Lusk, Ewing; Marcucci, L. E.; Pieper, Steven C.; Schiavilla, R.; Viviani, M.; Wiringa, R. B.

    2018-02-01

    In recent years local chiral interactions have been derived and implemented in quantum Monte Carlo methods in order to test to what extent the chiral effective field theory framework impacts our knowledge of few- and many-body systems. In this Letter, we present Green's function Monte Carlo calculations of light nuclei based on the family of local two-body interactions presented by our group in a previous paper in conjunction with chiral three-body interactions fitted to bound- and scattering-state observables in the three-nucleon sector. These interactions include Δ intermediate states in their two-pion-exchange components. We obtain predictions for the energy levels and level ordering of nuclei in the mass range A =4 - 12 , accurate to ≤2 % of the binding energy, in very satisfactory agreement with experimental data.

  12. Intelligent chiral sensing based on supramolecular and interfacial concepts.

    PubMed

    Ariga, Katsuhiko; Richards, Gary J; Ishihara, Shinsuke; Izawa, Hironori; Hill, Jonathan P

    2010-01-01

    Of the known intelligently-operating systems, the majority can undoubtedly be classed as being of biological origin. One of the notable differences between biological and artificial systems is the important fact that biological materials consist mostly of chiral molecules. While most biochemical processes routinely discriminate chiral molecules, differentiation between chiral molecules in artificial systems is currently one of the challenging subjects in the field of molecular recognition. Therefore, one of the important challenges for intelligent man-made sensors is to prepare a sensing system that can discriminate chiral molecules. Because intermolecular interactions and detection at surfaces are respectively parts of supramolecular chemistry and interfacial science, chiral sensing based on supramolecular and interfacial concepts is a significant topic. In this review, we briefly summarize recent advances in these fields, including supramolecular hosts for color detection on chiral sensing, indicator-displacement assays, kinetic resolution in supramolecular reactions with analyses by mass spectrometry, use of chiral shape-defined polymers, such as dynamic helical polymers, molecular imprinting, thin films on surfaces of devices such as QCM, functional electrodes, FET, and SPR, the combined technique of magnetic resonance imaging and immunoassay, and chiral detection using scanning tunneling microscopy and cantilever technology. In addition, we will discuss novel concepts in recent research including the use of achiral reagents for chiral sensing with NMR, and mechanical control of chiral sensing. The importance of integration of chiral sensing systems with rapidly developing nanotechnology and nanomaterials is also emphasized.

  13. How can we probe the atom mass currents induced by synthetic gauge fields?

    NASA Astrophysics Data System (ADS)

    Paramekanti, Arun; Killi, Matthew; Trotzky, Stefan

    2013-05-01

    Ultracold atomic fermions and bosons in an optical lattice can have quantum ground states which support equilibrium currents in the presence of synthetic magnetic fields or spin orbit coupling. As a tool to uncover these mass currents, we propose using an anisotropic quantum quench of the optical lattice which dynamically converts the current patterns into measurable density patterns. Using analytical calculations and numerical simulations, we show that this scheme can probe diverse equilibrium bulk current patterns in Bose superfluids and Fermi fluids induced by synthetic magnetic fields, as well as detect the chiral edge currents in topological states of atomic matter such as quantum Hall and quantum spin Hall insulators. This work is supported by NSERC of Canada and the Canadian Institute for Advanced Research.

  14. Chiral extrapolation of the leading hadronic contribution to the muon anomalous magnetic moment

    NASA Astrophysics Data System (ADS)

    Golterman, Maarten; Maltman, Kim; Peris, Santiago

    2017-04-01

    A lattice computation of the leading-order hadronic contribution to the muon anomalous magnetic moment can potentially help reduce the error on the Standard Model prediction for this quantity, if sufficient control of all systematic errors affecting such a computation can be achieved. One of these systematic errors is that associated with the extrapolation to the physical pion mass from values on the lattice larger than the physical pion mass. We investigate this extrapolation assuming lattice pion masses in the range of 200 to 400 MeV with the help of two-loop chiral perturbation theory, and we find that such an extrapolation is unlikely to lead to control of this systematic error at the 1% level. This remains true even if various tricks to improve the reliability of the chiral extrapolation employed in the literature are taken into account. In addition, while chiral perturbation theory also predicts the dependence on the pion mass of the leading-order hadronic contribution to the muon anomalous magnetic moment as the chiral limit is approached, this prediction turns out to be of no practical use because the physical pion mass is larger than the muon mass that sets the scale for the onset of this behavior.

  15. Search for a low-mass neutral Higgs boson with suppressed couplings to fermions using events with multiphoton final states

    NASA Astrophysics Data System (ADS)

    Aaltonen, T.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Butti, P.; Buzatu, A.; Calamba, A.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Chokheli, D.; Clark, A.; Clarke, C.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; d'Ascenzo, N.; Datta, M.; de Barbaro, P.; Demortier, L.; Deninno, M.; D'Errico, M.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; Donati, S.; D'Onofrio, M.; Dorigo, M.; Driutti, A.; Ebina, K.; Edgar, R.; Erbacher, R.; Errede, S.; Esham, B.; Farrington, S.; Fernández Ramos, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Franklin, M.; Freeman, J. C.; Frisch, H.; Funakoshi, Y.; Galloni, C.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González López, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gramellini, E.; Grosso-Pilcher, C.; Guimaraes da Costa, J.; Hahn, S. R.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, M.; Harr, R. F.; Harrington-Taber, T.; Hatakeyama, K.; Hays, C.; Heinrich, J.; Herndon, M.; Hocker, A.; Hong, Z.; Hopkins, W.; Hou, S.; Hughes, R. E.; Husemann, U.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kambeitz, M.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. H.; Kim, S. B.; Kim, Y. J.; Kim, Y. K.; Kimura, N.; Kirby, M.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kurata, M.; Laasanen, A. T.; Lammel, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lee, H. S.; Lee, J. S.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lipeles, E.; Lister, A.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lucà, A.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Marchese, L.; Margaroli, F.; Marino, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Nigmanov, T.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagliarone, C.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parker, W.; Pauletta, G.; Paulini, M.; Paus, C.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Redondo Fernández, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ristori, L.; Robson, A.; Rodriguez, T.; Rolli, S.; Ronzani, M.; Roser, R.; Rosner, J. L.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Song, H.; Sorin, V.; St. Denis, R.; Stancari, M.; Stentz, D.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thomson, E.; Thukral, V.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Vázquez, F.; Velev, G.; Vellidis, C.; Vernieri, C.; Vidal, M.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wallny, R.; Wang, S. M.; Waters, D.; Wester, W. C.; Whiteson, D.; Wicklund, A. B.; Wilbur, S.; Williams, H. H.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu, X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W.-M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Zanetti, A. M.; Zeng, Y.; Zhou, C.; Zucchelli, S.; CDF Collaboration

    2016-06-01

    A search for a Higgs boson with suppressed couplings to fermions, hf, assumed to be the neutral, lower-mass partner of the Higgs boson discovered at the Large Hadron Collider, is reported. Such a Higgs boson could exist in extensions of the standard model with two Higgs doublets, and could be produced via p p ¯→H±hf→W*hfhf→4 γ +X , where H± is a charged Higgs boson. This analysis uses all events with at least three photons in the final state from proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the Collider Detector at Fermilab, corresponding to an integrated luminosity of 9.2 fb-1. No evidence of a signal is observed in the data. Values of Higgs-boson masses between 10 and 100 GeV /c2 are excluded at 95% Bayesian credibility.

  16. Quantized charge transport in chiral Majorana edge modes

    NASA Astrophysics Data System (ADS)

    Rachel, Stephan; Mascot, Eric; Cocklin, Sagen; Vojta, Matthias; Morr, Dirk K.

    2017-11-01

    Majorana fermions can be realized as quasiparticles in topological superconductors, with potential applications in topological quantum computing. Recently, lattices of magnetic adatoms deposited on the surface of s -wave superconductors—Shiba lattices—have been proposed as a new platform for topological superconductivity. These systems possess the great advantage that they are accessible via scanning-probe techniques and thus enable the local manipulation and detection of Majorana modes. Using a nonequilibrium Green's function technique we demonstrate that the topological Majorana edge modes of nanoscopic Shiba islands display universal electronic and transport properties. Most remarkably, these Majorana modes possess a quantized charge conductance that is proportional to the topological Chern number, C , and carry a supercurrent whose chirality reflects the sign of C . These results establish nanoscopic Shiba islands as promising components in future topology-based devices.

  17. Chiral Dynamics 2006

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohammad W.; Gao, Haiyan; Weller, Henry R.; Holstein, Barry

    2007-10-01

    .5 GeV with BABAR / A. Denig. The pion vector form-factor and (g-2)u / C. Smith. Partially quenched CHPT results to two loops / J. Bijnens. Pion-pion scattering with mixed action lattice QCD / P.F. Bedaque. Meson systems with Ginsparg-Wilson valence quarks / A. Walker-Loud. Low energy constants from the MILC collaboration / C. Bernard. Finite volume effects: lattice meets CHPT / G. Schierholz. Lattice QCD simulations with two light dynamical (Wilson) quarks / L. Giusti. Do we understand the low-energy constant L8? / M. Golterman. Quark mass dependence of LECs in the two-flavour sector / M. Schmid. Progress report on the [Pie symbol]0 Lifetime experiment (PRIMEX) at Jlab / D.E. McNulty. Determination of the charged pion polarizabilities / L.V. Fil'kov. Proposed measurement of electroproduction of [Pie symbol]0 near threshold using a large acceptance spectrometer / R.A. Lindgren. The [Pie symbol] meson in [Pie symbol]K scattering / B. Moussallam. Strangeness -1 Meson-Baryon scattering S-wave / J.A. Oller. Results on light mesons decays and dynamics at KLOE / M. Martini. Studies of decays of [symbol] and [symbol] mesons with WASA detector / A. Kupsc. Heavy Quark-Diquark symmetry and X PT for doubly heavy baryons / T. Mehen. HHChPT applied to the charmed-strange parity partners/ R.P. Springer. Study of pion structure through precise measurements of the [Pie symbol]+ --> e+[symbol] decay / D. Pocanic. Exceptional and non-exceptional contributions to the radiative [Pie symbol] decay / V. Mateu. Leading chiral logarithms from unitarity, analyticity and the Roy equations / A. Fuhrer. All orders symmetric subtraction of the nonlinear sigma model in D=4 / A. Quadri -- pt. C. Chiral dynamics in few-nucleon systems. Working group summary: chiral dynamics in few-nucleon systems / H.W Hammer, N. Kalantar-Nayestanaki, and D.R. Phillips. Power counting in nuclear chiral effective field theory / U. van Kolck. On the consistency of Weinberg's power counting / U-G Mei ner. Renormalization

  18. Chiral superconductors.

    PubMed

    Kallin, Catherine; Berlinsky, John

    2016-05-01

    Chiral superconductivity is a striking quantum phenomenon in which an unconventional superconductor spontaneously develops an angular momentum and lowers its free energy by eliminating nodes in the gap. It is a topologically non-trivial state and, as such, exhibits distinctive topological modes at surfaces and defects. In this paper we discuss the current theory and experimental results on chiral superconductors, focusing on two of the best-studied systems, Sr2RuO4, which is thought to be a chiral triplet p-wave superconductor, and UPt3, which has two low-temperature superconducting phases (in zero magnetic field), the lower of which is believed to be chiral triplet f-wave. Other systems that may exhibit chiral superconductivity are also discussed. Key signatures of chiral superconductivity are surface currents and chiral Majorana modes, Majorana states in vortex cores, and the possibility of half-flux quantum vortices in the case of triplet pairing. Experimental evidence for chiral superconductivity from μSR, NMR, strain, polar Kerr effect and Josephson tunneling experiments are discussed.

  19. Light-Nuclei Spectra from Chiral Dynamics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Piarulli, M.; Baroni, A.; Girlanda, L.

    In recent years local chiral interactions have been derived and implemented in quantum Monte Carlo methods in order to test to what extent the chiral effective field theory framework impacts our knowledge of few- and many-body systems. Here in this Letter, we present Green’s function Monte Carlo calculations of light nuclei based on the family of local two-body interactions presented by our group in a previous paper in conjunction with chiral three-body interactions fitted to bound- and scattering-state observables in the three-nucleon sector. These interactions include Δ intermediate states in their two-pion-exchange components. We obtain predictions for the energy levelsmore » and level ordering of nuclei in the mass range A=4–12, accurate to ≤2% of the binding energy, in very satisfactory agreement with experimental data.« less

  20. Light-Nuclei Spectra from Chiral Dynamics

    DOE PAGES

    Piarulli, M.; Baroni, A.; Girlanda, L.; ...

    2018-02-01

    In recent years local chiral interactions have been derived and implemented in quantum Monte Carlo methods in order to test to what extent the chiral effective field theory framework impacts our knowledge of few- and many-body systems. Here in this Letter, we present Green’s function Monte Carlo calculations of light nuclei based on the family of local two-body interactions presented by our group in a previous paper in conjunction with chiral three-body interactions fitted to bound- and scattering-state observables in the three-nucleon sector. These interactions include Δ intermediate states in their two-pion-exchange components. We obtain predictions for the energy levelsmore » and level ordering of nuclei in the mass range A=4–12, accurate to ≤2% of the binding energy, in very satisfactory agreement with experimental data.« less

  1. Topological phase in a two-dimensional metallic heavy-fermion system

    NASA Astrophysics Data System (ADS)

    Yoshida, Tsuneya; Peters, Robert; Fujimoto, Satoshi; Kawakami, Norio

    2013-04-01

    We report on a topological insulating state in a heavy-fermion system away from half filling, which is hidden within a ferromagnetic metallic phase. In this phase, the cooperation of the RKKY interaction and the Kondo effect, together with the spin-orbit coupling, induces a spin-selective gap, bringing about topologically nontrivial properties. This topological phase is robust against a change in the chemical potential in a much wider range than the gap size. We analyze these remarkable properties by using dynamical mean field theory and the numerical renormalization group. Its topological properties support a gapless chiral edge mode, which exhibits a non-Tomonaga-Luttinger liquid behavior due to the coupling with bulk ferromagnetic spin fluctuations. We also propose that the effects of the spin fluctuations on the edge mode can be detected via the NMR relaxation time measurement.

  2. FAST TRACK COMMUNICATION: Exact and simple results for the XYZ and strongly interacting fermion chains

    NASA Astrophysics Data System (ADS)

    Fendley, Paul; Hagendorf, Christian

    2010-10-01

    We conjecture exact and simple formulas for some physical quantities in two quantum chains. A classic result of this type is Onsager, Kaufman and Yang's formula for the spontaneous magnetization in the Ising model, subsequently generalized to the chiral Potts models. We conjecture that analogous results occur in the XYZ chain when the couplings obey JxJy + JyJz + JxJz = 0, and in a related fermion chain with strong interactions and supersymmetry. We find exact formulas for the magnetization and gap in the former, and the staggered density in the latter, by exploiting the fact that certain quantities are independent of finite-size effects.

  3. Chiral Recognition and Separation by Chirality-Enriched Metal-Organic Frameworks.

    PubMed

    Das, Saikat; Xu, Shixian; Ben, Teng; Qiu, Shilun

    2018-05-16

    Endowed with chiral channels and pores, chiral metal-organic frameworks (MOFs) are highly useful; however, their synthesis remains a challenge given that most chiral building blocks are expensive. Although MOFs with induced chirality have been reported to avoid this shortcoming, no study providing evidence for the ee value of such MOFs has yet been reported. We herein describe the first study on the efficiency of chiral induction in MOFs using inexpensive achiral building blocks and fully recoverable chiral dopants to control the handedness of racemic MOFs. This method yielded chirality-enriched MOFs with accessible pores. The ability of the materials to form host-guest complexes was probed with enantiomers of varying size and coordination and in solvents with varying polarity. Furthermore, mixed-matrix membranes (MMMs) composed of chirality-enriched MOF particles dispersed in a polymer matrix demonstrated a new route for chiral separation. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Magnetotransport study of Dirac fermions in YbMnBi 2 antiferromagnet

    DOE PAGES

    Wang, Aifeng; Zaliznyak, I.; Ren, Weijun; ...

    2016-10-15

    We report quantum transport and Dirac fermions in YbMnBi 2 single crystals. YbMnBi 2 is a layered material with anisotropic conductivity and magnetic order below 290 K. Magnetotransport properties, nonzero Berry phase, and small cyclotron mass indicate the presence of Dirac fermions. Lastly, angular-dependent magnetoresistance indicates a possible quasi-two-dimensional Fermi surface, whereas the deviation from the nontrivial Berry phase expected for Dirac states suggests the contribution of parabolic bands at the Fermi level or spin-orbit coupling.

  5. Evidence for trivial Berry phase and absence of chiral anomaly in semimetal NbP

    NASA Astrophysics Data System (ADS)

    Sudesh; Kumar, Pawan; Neha, Prakriti; Das, Tanmoy; Patnaik, Satyabrata

    2017-04-01

    The discovery of Weyl semimetals (WSM) has brought forth the condensed matter realization of Weyl fermions, which were previously theorized as low energy excitations in high energy particle physics. Recently, transition metal mono-pnictides are under intense investigation for understanding properties of inversion-symmetry broken Weyl semimetals. Non-trivial Berry phase and chirality are important markers for characterizing topological aspects of Weyl semimetals. Most recently, theoretical calculations predict strong influence of the position of Weyl nodes with respect to Fermi surface and weak disorder that can drive WSMs into chirally symmetric Dirac semimetals. Using magneto-transport measurements in single crystals of WSM NbP, we observe an exceptionally large magnetoresistance at low temperature, which is non-saturating and linear at high fields. The origin of linear transverse magnetoresistance is assigned to charge carrier mobility fluctuations. Negative longitudinal magnetoresistance is not seen, suggesting lack of well-defined chiral anomaly in NbP. Unambiguous Shubnikov-de Haas oscillations are observed at low temperatures that are correlated to a trivial Berry phase corresponding to Fermi surface extrema at 30.5 Tesla. Our results are important towards identifying topological characteristics of Weyl semimetals and their experimental manifestations in the presence of weak disorder.

  6. Baryon masses and axial couplings in the combined 1/N{sub c} and Chiral expansions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Alvaro Calle Cordon, Jose Goity

    The effective theory for baryons with a combined 1/N{sub c} and chiral expansions is analyzed for non-strange baryons. Results for baryon masses and axial couplings are obtained in the small scale expansion, to be coined as the {xi}-expansion, in which the 1/N{sub c} and the low energy power countings are linked according to 1/N{sub c}=O({xi})=O(p). Masses and axial couplings are analyzed to O({xi}{sup 3}) and O({xi}{sup 2}) respectively, which correspond to next-to-next to leading order evaluations, and require one-loop contributions in the effective theory. The role of the spin-flavor approximate symmetry in baryons, consequence of the large N{sub c} limit,more » is manifested in the physical world with N{sub c}=3 in a significant way, as the analysis of its breaking in the masses and the axial couplings show. Applications to the recent lattice QCD results on baryon masses and the nucleon's axial coupling are presented. It is shown that those results are naturally described within the effective theory at the order considered in the {xi}-expansion.« less

  7. Search for a Low-Mass Neutral Higgs Boson with Suppressed Couplings to Fermions Using Events with Multiphoton Final States

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aaltonen, Timo Antero

    A search for a Higgs boson with suppressed couplings to fermions,more » $$h_f$$, assumed to be the neutral, lower-mass partner of the Higgs boson discovered at the Large Hadron Collider, is reported. Such a Higgs boson could exist in extensions of the standard model with two Higgs doublets, and could be produced via $$p\\bar{p} \\to H^\\pm h_f \\to W^* h_f h_f \\to 4\\gamma + X$$, where $$H^\\pm$$ is a charged Higgs boson. This analysis uses all events with at least three photons in the final state from proton-antiproton collisions at a center-of-mass energy of 1.96~TeV collected by the Collider Detector at Fermilab, corresponding to an integrated luminosity of 9.2~$${\\rm fb}^{-1}$$. No evidence of a signal is observed in the data. Values of Higgs-boson masses between 10 and 100 GeV/$c^2$ are excluded at 95\\% Bayesian credibility.« less

  8. Search for a Low-Mass Neutral Higgs Boson with Suppressed Couplings to Fermions Using Events with Multiphoton Final States

    DOE PAGES

    Aaltonen, Timo Antero

    2016-06-20

    A search for a Higgs boson with suppressed couplings to fermions,more » $$h_f$$, assumed to be the neutral, lower-mass partner of the Higgs boson discovered at the Large Hadron Collider, is reported. Such a Higgs boson could exist in extensions of the standard model with two Higgs doublets, and could be produced via $$p\\bar{p} \\to H^\\pm h_f \\to W^* h_f h_f \\to 4\\gamma + X$$, where $$H^\\pm$$ is a charged Higgs boson. This analysis uses all events with at least three photons in the final state from proton-antiproton collisions at a center-of-mass energy of 1.96~TeV collected by the Collider Detector at Fermilab, corresponding to an integrated luminosity of 9.2~$${\\rm fb}^{-1}$$. No evidence of a signal is observed in the data. Values of Higgs-boson masses between 10 and 100 GeV/$c^2$ are excluded at 95\\% Bayesian credibility.« less

  9. Nature of the chiral restoration transition in QCD

    NASA Astrophysics Data System (ADS)

    Brown, Gerald E.; Grandchamp, Loı̈c.; Lee, Chang-Hwan; Rho, Mannque

    2004-03-01

    As the chirally restored phase ends with T coming down to Tc, a phase resembling a mixed phase is realized, during which the hadrons (which are massless at Tc in the chiral limit) get their masses back out of their kinetic energy. The gluon condensation energy is fed into the system to keep the temperature (nearly) constant. Lattice results for the gluon condensation are matched by a Nambu-Jona-Lasinio calculation. The latter shows that below Tc the chiral symmetry is barely broken, so that with an ˜6% drop in the scalar coupling G it is restored at Tc. Nearly half of the glue, which we call epoxy, is not melted at Tc.

  10. MSW-resonant fermion mixing during reheating

    NASA Astrophysics Data System (ADS)

    Kanai, Tsuneto; Tsujikawa, Shinji

    2003-10-01

    We study the dynamics of reheating in which an inflaton field couples two flavor fermions through Yukawa-couplings. When two fermions have a mixing term with a constant coupling, we show that the Mikheyev-Smirnov-Wolfenstein (MSW)-type resonance emerges due to a time-dependent background in addition to the standard fermion creation via parametric resonance. This MSW resonance not only alters the number densities of fermions generated by a preheating process but also can lead to the larger energy transfer from the inflaton to fermions. Our mechanism can provide additional source terms for the creation of superheavy fermions which may be relevant for the leptogenesis scenario.

  11. On bound-states of the Gross Neveu model with massive fundamental fermions

    NASA Astrophysics Data System (ADS)

    Frishman, Yitzhak; Sonnenschein, Jacob

    2018-01-01

    In the search for QFT's that admit boundstates, we reinvestigate the two dimensional Gross-Neveu model, but with massive fermions. By computing the self-energy for the auxiliary boundstate field and the effective potential, we show that there are no bound states around the lowest minimum, but there is a meta-stable bound state around the other minimum, a local one. The latter decays by tunneling. We determine the dependence of its lifetime on the fermion mass and coupling constant.

  12. Scattering of fermions in the Yukawa theory coupled to unimodular gravity

    NASA Astrophysics Data System (ADS)

    Gonzalez-Martin, S.; Martin, C. P.

    2018-03-01

    We compute the lowest order gravitational UV divergent radiative corrections to the S matrix element of the fermion + fermion→ fermion + fermion scattering process in the massive Yukawa theory, coupled either to Unimodular Gravity or to General Relativity. We show that both Unimodular Gravity and General Relativity give rise to the same UV divergent contribution in Dimensional Regularization. This is a nontrivial result, since in the classical action of Unimodular Gravity coupled to the Yukawa theory, the graviton field does not couple neither to the mass operator nor to the Yukawa operator. This is unlike the General Relativity case. The agreement found points in the direction that Unimodular Gravity and General Relativity give rise to the same quantum theory when coupled to matter, as long as the Cosmological Constant vanishes. Along the way we have come across another unexpected cancellation of UV divergences for both Unimodular Gravity and General Relativity, resulting in the UV finiteness of the one-loop and κ y^2 order of the vertex involving two fermions and one graviton only.

  13. Superfluidity of identical fermions in an optical lattice: Atoms and polar molecules

    NASA Astrophysics Data System (ADS)

    Fedorov, A. K.; Yudson, V. I.; Shlyapnikov, G. V.

    2018-02-01

    In this work we discuss the emergence of p-wave superfluids of identical fermions in 2D lattices. The optical lattice potential manifests itself in an interplay between an increase in the density of states on the Fermi surface and the modification of the fermion-fermion interaction (scattering) amplitude. The density of states is enhanced due to an increase of the effective mass of atoms. In deep lattices, for short-range interacting atoms the scattering amplitude is strongly reduced compared to free space due to a small overlap of wavefunctions of fermions sitting in the neighboring lattice sites, which suppresses the p-wave superfluidity. However, we show that for a moderate lattice depth there is still a possibility to create atomic p-wave superfluids with sizable transition temperatures. The situation is drastically different for fermionic polar molecules. Being dressed with a microwave field, they acquire a dipole-dipole attractive tail in the interaction potential. Then, due to a long-range character of the dipole-dipole interaction, the effect of the suppression of the scattering amplitude in 2D lattices is absent. This leads to the emergence of a stable topological px + ipy superfluid of identical microwave-dressed polar molecules.

  14. Chiral Lagrangian with Heavy Quark-Diquark Symmetry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jie Hu; Thomas Mehen

    2005-11-29

    We construct a chiral Lagrangian for doubly heavy baryons and heavy mesons that is invariant under heavy quark-diquark symmetry at leading order and includes the leading O(1/m{sub Q}) symmetry violating operators. The theory is used to predict the electromagnetic decay width of the J=3/2 member of the ground state doubly heavy baryon doublet. Numerical estimates are provided for doubly charm baryons. We also calculate chiral corrections to doubly heavy baryon masses and strong decay widths of low lying excited doubly heavy baryons.

  15. QCD equation of state with almost physical quark masses

    NASA Astrophysics Data System (ADS)

    Cheng, M.; Christ, N. H.; Datta, S.; van der Heide, J.; Jung, C.; Karsch, F.; Kaczmarek, O.; Laermann, E.; Mawhinney, R. D.; Miao, C.; Petreczky, P.; Petrov, K.; Schmidt, C.; Soeldner, W.; Umeda, T.

    2008-01-01

    We present results on the equation of state in QCD with two light quark flavors and a heavier strange quark. Calculations with improved staggered fermions have been performed on lattices with temporal extent Nτ=4 and 6 on a line of constant physics with almost physical quark mass values; the pion mass is about 220 MeV, and the strange quark mass is adjusted to its physical value. High statistics results on large lattices are obtained for bulk thermodynamic observables, i.e. pressure, energy and entropy density, at vanishing quark chemical potential for a wide range of temperatures, 140MeV≤T≤800MeV. We present a detailed discussion of finite cutoff effects which become particularly significant for temperatures larger than about twice the transition temperature. At these high temperatures we also performed calculations of the trace anomaly on lattices with temporal extent Nτ=8. Furthermore, we have performed an extensive analysis of zero temperature observables including the light and strange quark condensates and the static quark potential at zero temperature. These are used to set the temperature scale for thermodynamic observables and to calculate renormalized observables that are sensitive to deconfinement and chiral symmetry restoration and become order parameters in the infinite and zero quark mass limits, respectively.

  16. Multi-boson block factorization of fermions

    NASA Astrophysics Data System (ADS)

    Giusti, Leonardo; Cè, Marco; Schaefer, Stefan

    2018-03-01

    The numerical computations of many quantities of theoretical and phenomenological interest are plagued by statistical errors which increase exponentially with the distance of the sources in the relevant correlators. Notable examples are baryon masses and matrix elements, the hadronic vacuum polarization and the light-by-light scattering contributions to the muon g - 2, and the form factors of semileptonic B decays. Reliable and precise determinations of these quantities are very difficult if not impractical with state-of-the-art standard Monte Carlo integration schemes. I will review a recent proposal for factorizing the fermion determinant in lattice QCD that leads to a local action in the gauge field and in the auxiliary boson fields. Once combined with the corresponding factorization of the quark propagator, it paves the way for multi-level Monte Carlo integration in the presence of fermions opening new perspectives in lattice QCD. Exploratory results on the impact on the above mentioned observables will be presented.

  17. Chiral geometry in multiple chiral doublet bands

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Chen, Qibo

    2016-02-01

    The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with . The energy spectra, electromagnetic transition probabilities B(M1) and B(E2), angular momenta, and K-distributions are studied. It is demonstrated that the chirality still remains not only in the yrast and yrare bands, but also in the two higher excited bands when γ deviates from 30°. The chiral geometry relies significantly on γ, and the chiral geometry of the two higher excited partner bands is not as good as that of the yrast and yrare doublet bands. Supported by Plan Project of Beijing College Students’ Scientific Research and Entrepreneurial Action, Major State 973 Program of China (2013CB834400), National Natural Science Foundation of China (11175002, 11335002, 11375015, 11461141002), National Fund for Fostering Talents of Basic Science (NFFTBS) (J1103206), Research Fund for Doctoral Program of Higher Education (20110001110087) and China Postdoctoral Science Foundation (2015M580007)

  18. Chiral acidic amino acids induce chiral hierarchical structure in calcium carbonate

    PubMed Central

    Jiang, Wenge; Pacella, Michael S.; Athanasiadou, Dimitra; Nelea, Valentin; Vali, Hojatollah; Hazen, Robert M.; Gray, Jeffrey J.; McKee, Marc D.

    2017-01-01

    Chirality is ubiquitous in biology, including in biomineralization, where it is found in many hardened structures of invertebrate marine and terrestrial organisms (for example, spiralling gastropod shells). Here we show that chiral, hierarchically organized architectures for calcium carbonate (vaterite) can be controlled simply by adding chiral acidic amino acids (Asp and Glu). Chiral, vaterite toroidal suprastructure having a ‘right-handed' (counterclockwise) spiralling morphology is induced by L-enantiomers of Asp and Glu, whereas ‘left-handed' (clockwise) morphology is induced by D-enantiomers, and sequentially switching between amino-acid enantiomers causes a switch in chirality. Nanoparticle tilting after binding of chiral amino acids is proposed as a chiral growth mechanism, where a ‘mother' subunit nanoparticle spawns a slightly tilted, consequential ‘daughter' nanoparticle, which by amplification over various length scales creates oriented mineral platelets and chiral vaterite suprastructures. These findings suggest a molecular mechanism for how biomineralization-related enantiomers might exert hierarchical control to form extended chiral suprastructures. PMID:28406143

  19. Spin-orbit beams for optical chirality measurement

    NASA Astrophysics Data System (ADS)

    Samlan, C. T.; Suna, Rashmi Ranjan; Naik, Dinesh N.; Viswanathan, Nirmal K.

    2018-01-01

    Accurate measurement of chirality is essential for the advancement of natural and pharmaceutical sciences. We report here a method to measure chirality using non-separable states of light with geometric phase-gradient in the circular polarization basis, which we refer to as spin-orbit beams. A modified polarization Sagnac interferometer is used to generate spin-orbit beams wherein the spin and orbital angular momentum of the input Gaussian beam are coupled. The out-of-phase interference between counter-propagating Gaussian beams with orthogonal spin states and lateral-shear or/and linear-phase difference between them results in spin-orbit beams with linear and azimuthal phase gradient. The spin-orbit beams interact efficiently with the chiral medium, inducing a measurable change in the center-of-mass of the beam, using the polarization rotation angle and hence the chirality of the medium are accurately calculated. Tunable dynamic range of measurement and flexibility to introduce large values of orbital angular momentum for the spin-orbit beam, to improve the measurement sensitivity, highlight the techniques' versatility.

  20. WTO — a deterministic approach to 4-fermion physics

    NASA Astrophysics Data System (ADS)

    Passarino, Giampiero

    1996-09-01

    The program WTO, which is designed for computing cross sections and other relevant observables in the e+e- annihilation into four fermions, is described. The various quantities are computed over both a completely inclusive experimental set-up and a realistic one, i.e. with cuts on the final state energies, final state angles, scattering angles and final state invariant masses. Initial state QED corrections are included by means of the structure function approach while final state QCD corrections are applicable in their naive formulation. A gauge restoring mechanism is included according to the Fermion-Loop scheme. The program structure is highly modular and particular care has been devoted to computing efficiency and speed.

  1. Discovery of Weyl Fermion Semimetals and Topological Fermi Arc States

    NASA Astrophysics Data System (ADS)

    Hasan, M. Zahid; Xu, Su-Yang; Belopolski, Ilya; Huang, Shin-Ming

    2017-03-01

    Weyl semimetals are conductors whose low-energy bulk excitations are Weyl fermions, whereas their surfaces possess metallic Fermi arc surface states. These Fermi arc surface states are protected by a topological invariant associated with the bulk electronic wave functions of the material. Recently, it has been shown that the TaAs and NbAs classes of materials harbor such a state of topological matter. We review the basic phenomena and experimental history of the discovery of the first Weyl semimetals, starting with the observation of topological Fermi arcs and Weyl nodes in TaAs and NbAs by angle and spin-resolved surface and bulk sensitive photoemission spectroscopy and continuing through magnetotransport measurements reporting the Adler-Bell-Jackiw chiral anomaly. We hope that this article provides a useful introduction to the theory of Weyl semimetals, a summary of recent experimental discoveries, and a guideline to future directions.

  2. Predicted Realization of Cubic Dirac Fermion in Quasi-One-Dimensional Transition-Metal Monochalcogenides

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Qihang; Zunger, Alex

    We show that the previously predicted “cubic Dirac fermion,” composed of six conventional Weyl fermions including three with left-handed and three with right-handed chirality, is realized in a specific, stable solid state system that has been made years ago, but was not appreciated as a “cubically dispersed Dirac semimetal” (CDSM). We identify the crystal symmetry constraints and find the space group P6 3/m as one of the two that can support a CDSM, of which the characteristic band crossing has linear dispersion along the principle axis but cubic dispersion in the plane perpendicular to it. We then conduct a materialmore » search using density functional theory, identifying a group of quasi-one-dimensional molybdenum monochalcogenide compounds A I(MoX VI) 3 (AI = Na, K, Rb, In, Tl; X VI = S , Se, Te) as ideal CDSM candidates. Studying the stability of the A ( MoX ) 3 family reveals a few candidates such as Rb(MoTe) 3 and Tl(MoTe) 3 that are predicted to be resilient to Peierls distortion, thus retaining the metallic character. Furthermore, the combination of one dimensionality and metallic nature in this family provides a platform for unusual optical signature—polarization-dependent metallic vs insulating response.« less

  3. Predicted Realization of Cubic Dirac Fermion in Quasi-One-Dimensional Transition-Metal Monochalcogenides

    NASA Astrophysics Data System (ADS)

    Liu, Qihang; Zunger, Alex

    2017-04-01

    We show that the previously predicted "cubic Dirac fermion," composed of six conventional Weyl fermions including three with left-handed and three with right-handed chirality, is realized in a specific, stable solid state system that has been made years ago, but was not appreciated as a "cubically dispersed Dirac semimetal" (CDSM). We identify the crystal symmetry constraints and find the space group P 63/m as one of the two that can support a CDSM, of which the characteristic band crossing has linear dispersion along the principle axis but cubic dispersion in the plane perpendicular to it. We then conduct a material search using density functional theory, identifying a group of quasi-one-dimensional molybdenum monochalcogenide compounds AI(MoXVI)3 (AI=Na , K, Rb, In, Tl; XVI=S , Se, Te) as ideal CDSM candidates. Studying the stability of the A (MoX) 3 family reveals a few candidates such as Rb (MoTe) 3 and Tl (MoTe) 3 that are predicted to be resilient to Peierls distortion, thus retaining the metallic character. Furthermore, the combination of one dimensionality and metallic nature in this family provides a platform for unusual optical signature—polarization-dependent metallic vs insulating response.

  4. Predicted Realization of Cubic Dirac Fermion in Quasi-One-Dimensional Transition-Metal Monochalcogenides

    DOE PAGES

    Liu, Qihang; Zunger, Alex

    2017-05-09

    We show that the previously predicted “cubic Dirac fermion,” composed of six conventional Weyl fermions including three with left-handed and three with right-handed chirality, is realized in a specific, stable solid state system that has been made years ago, but was not appreciated as a “cubically dispersed Dirac semimetal” (CDSM). We identify the crystal symmetry constraints and find the space group P6 3/m as one of the two that can support a CDSM, of which the characteristic band crossing has linear dispersion along the principle axis but cubic dispersion in the plane perpendicular to it. We then conduct a materialmore » search using density functional theory, identifying a group of quasi-one-dimensional molybdenum monochalcogenide compounds A I(MoX VI) 3 (AI = Na, K, Rb, In, Tl; X VI = S , Se, Te) as ideal CDSM candidates. Studying the stability of the A ( MoX ) 3 family reveals a few candidates such as Rb(MoTe) 3 and Tl(MoTe) 3 that are predicted to be resilient to Peierls distortion, thus retaining the metallic character. Furthermore, the combination of one dimensionality and metallic nature in this family provides a platform for unusual optical signature—polarization-dependent metallic vs insulating response.« less

  5. Simulating Chiral Magnetic and Separation Effects with Spin-Orbit Coupled Atomic Gases

    PubMed Central

    Huang, Xu-Guang

    2016-01-01

    The chiral magnetic and chiral separation effects—quantum-anomaly-induced electric current and chiral current along an external magnetic field in parity-odd quark-gluon plasma—have received intense studies in the community of heavy-ion collision physics. We show that analogous effects occur in rotating trapped Fermi gases with Weyl-Zeeman spin-orbit coupling where the rotation plays the role of an external magnetic field. These effects can induce a mass quadrupole in the atomic cloud along the rotation axis which may be tested in future experiments. Our results suggest that the spin-orbit coupled atomic gases are potential simulators of the chiral magnetic and separation effects. PMID:26868084

  6. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cartas-Fuentevilla, Roberto; Escalante, Alberto; Germán, Gabriel

    Following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the solution of the gauge hierarchy problem, the localization of fermion fields in this model, the recovering of the Coulomb law on the non-relativistic limit of the Yukawa interaction between bulk fermions and gauge bosons localized in the brane, and confront the predicted 5D corrections to the photon mass with its upper experimental/observational bounds, finding the model physically viable since it passes these tests. In order to achieve the latter aimsmore » we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ-bar in the action and analyze four distinct tachyonic functions F(T) that lead to four different structures of the respective fermionic mass spectra with different physics. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of these Yukawa interactions among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb’s law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb’s law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb’s law for an arbitrarily thick brane scenario which can be interpreted as 5D corrections to the photon mass. By performing consistent estimations with brane phenomenology, we found that the predicted corrections to the photon mass, which are well bounded by the

  7. Chiral Cliffs: Investigating the Influence of Chirality on Binding Affinity.

    PubMed

    Schneider, Nadine; Lewis, Richard A; Fechner, Nikolas; Ertl, Peter

    2018-05-11

    Chirality is understood by many as a binary concept: a molecule is either chiral or it is not. In terms of the action of a structure on polarized light, this is indeed true. When examined through the prism of molecular recognition, the answer becomes more nuanced. In this work, we investigated chiral behavior on protein-ligand binding: when does chirality make a difference in binding activity? Chirality is a property of the 3D structure, so recognition also requires an appreciation of the conformation. In many situations, the bioactive conformation is undefined. We set out to address this by defining and using several novel 2D descriptors to capture general characteristic features of the chiral center. Using machine-learning methods, we built different predictive models to estimate if a chiral pair (a set of two enantiomers) might exhibit a chiral cliff in a binding assay. A set of about 3800 chiral pairs extracted from the ChEMBL23 database was used to train and test our models. By achieving an accuracy of up to 75 %, our models provide good performance in discriminating chiral cliffs from non-cliffs. More importantly, we were able to derive some simple guidelines for when one can reasonably use a racemate and when an enantiopure compound is needed in an assay. We critically discuss our results and show detailed examples of using our guidelines. Along with this publication we provide our dataset, our novel descriptors, and the Python code to rebuild the predictive models. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Equation of state and QCD transition at finite temperature

    NASA Astrophysics Data System (ADS)

    Bazavov, A.; Bhattacharya, T.; Cheng, M.; Christ, N. H.; Detar, C.; Ejiri, S.; Gottlieb, Steven; Gupta, R.; Heller, U. M.; Huebner, K.; Jung, C.; Karsch, F.; Laermann, E.; Levkova, L.; Miao, C.; Mawhinney, R. D.; Petreczky, P.; Schmidt, C.; Soltz, R. A.; Soeldner, W.; Sugar, R.; Toussaint, D.; Vranas, P.

    2009-07-01

    We calculate the equation of state in 2+1 flavor QCD at finite temperature with physical strange quark mass and almost physical light quark masses using lattices with temporal extent Nτ=8. Calculations have been performed with two different improved staggered fermion actions, the asqtad and p4 actions. Overall, we find good agreement between results obtained with these two O(a2) improved staggered fermion discretization schemes. A comparison with earlier calculations on coarser lattices is performed to quantify systematic errors in current studies of the equation of state. We also present results for observables that are sensitive to deconfining and chiral aspects of the QCD transition on Nτ=6 and 8 lattices. We find that deconfinement and chiral symmetry restoration happen in the same narrow temperature interval. In an appendix we present a simple parametrization of the equation of state that can easily be used in hydrodynamic model calculations. In this parametrization we include an estimate of current uncertainties in the lattice calculations which arise from cutoff and quark mass effects.

  9. Electric line source illumination of a chiral cylinder placed in another chiral background medium

    NASA Astrophysics Data System (ADS)

    Aslam, M.; Saleem, A.; Awan, Z. A.

    2018-05-01

    An electric line source illumination of a chiral cylinder embedded in a chiral background medium is considered. The field expressions inside and outside of a chiral cylinder have been derived using the wave field decomposition approach. The effects of various chiral cylinders, chiral background media and source locations upon the scattering gain pattern have been investigated. It is observed that the chiral background reduces the backward scattering gain as compared to the free space background for a dielectric cylinder. It is also studied that by moving a line source away from a cylinder reduces the backward scattering gain for a chiral cylinder placed in a chiral background under some specific conditions. A unique phenomenon of reduced scattering gain has been observed at a specific observation angle for a chiral cylinder placed in a chiral background having an electric line source location of unity free space wavelength. An isotropic scattering gain pattern is observed for a chiral nihility background provided that if cylinder is chiral or chiral nihility type. It is also observed that this isotropic behaviour is independent of background and cylinder chirality.

  10. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Trewartha, Daniel; Kamleh, Waseem; Leinweber, Derek B.

    The influence of centre vortices on dynamical chiral symmetry breaking is investigated through the light hadron spectrum on the lattice. Recent studies of the quark propagator and other quantities have provided evidence that centre vortices are the fundamental objects underpinning dynamical chiral symmetry breaking in SU(3) gauge theory. For the first time, we use the chiral overlap fermion action to study the low-lying hadron spectrum on lattice ensembles consisting of Monte Carlo, vortex-removed, and vortex-projected gauge fields. We find that gauge field configurations consisting solely of smoothed centre vortices are capable of reproducing all the salient features of the hadronmore » spectrum, including dynamical chiral symmetry breaking. In conclusion, the hadron spectrum on vortex-removed fields shows clear signals of chiral symmetry restoration at light values of the bare quark mass, while at heavy masses the spectrum is consistent with a theory of weakly-interacting constituent quarks.« less

  11. The Fermionic Signature Operator and Hadamard States in the Presence of a Plane Electromagnetic Wave

    NASA Astrophysics Data System (ADS)

    Finster, Felix; Reintjes, Moritz

    2017-05-01

    We give a non-perturbative construction of a distinguished state for the quantized Dirac field in Minkowski space in the presence of a time-dependent external field of the form of a plane electromagnetic wave. By explicit computation of the fermionic signature operator, it is shown that the Dirac operator has the strong mass oscillation property. We prove that the resulting fermionic projector state is a Hadamard state.

  12. Chiral symmetry breaking in QCD with two light flavors.

    PubMed

    Engel, Georg P; Giusti, Leonardo; Lottini, Stefano; Sommer, Rainer

    2015-03-20

    A distinctive feature of the presence of spontaneous chiral symmetry breaking in QCD is the condensation of low modes of the Dirac operator near the origin. The rate of condensation must be equal to the slope of M(π)(2)F(π)(2)/2 with respect to the quark mass m in the chiral limit, where M(π) and F(π) are the mass and the decay constant of the Nambu-Goldstone bosons. We compute the spectral density of the (Hermitian) Dirac operator, the quark mass, the pseudoscalar meson mass, and decay constant by numerical simulations of lattice QCD with two light degenerate Wilson quarks. We use lattices generated by the Coordinated Lattice Simulation (CLS) group at three values of the lattice spacing in the range 0.05-0.08 fm, and for several quark masses corresponding to pseudoscalar mesons masses down to 190 MeV. Thanks to this coverage of parameters space, we can extrapolate all quantities to the chiral and continuum limits with confidence. The results show that the low quark modes do condense in the continuum as expected by the Banks-Casher mechanism, and the rate of condensation agrees with the Gell-Mann-Oakes-Renner relation. For the renormalization-group-invariant ratios we obtain [Σ(RGI)](1/3)/F=2.77(2)(4) and Λ(M̅S)/F=3.6(2), which correspond to [Σ(M̅S)(2  GeV)](1/3)=263(3)(4)  MeV and F=85.8(7)(20)  MeV if F(K) is used to set the scale by supplementing the theory with a quenched strange quark.

  13. Active chiral fluids.

    PubMed

    Fürthauer, S; Strempel, M; Grill, S W; Jülicher, F

    2012-09-01

    Active processes in biological systems often exhibit chiral asymmetries. Examples are the chirality of cytoskeletal filaments which interact with motor proteins, the chirality of the beat of cilia and flagella as well as the helical trajectories of many biological microswimmers. Here, we derive constitutive material equations for active fluids which account for the effects of active chiral processes. We identify active contributions to the antisymmetric part of the stress as well as active angular momentum fluxes. We discuss four types of elementary chiral motors and their effects on a surrounding fluid. We show that large-scale chiral flows can result from the collective behavior of such motors even in cases where isolated motors do not create a hydrodynamic far field.

  14. Electron-hole asymmetry, Dirac fermions, and quantum magnetoresistance in BaMnBi 2

    DOE PAGES

    Li, Lijun; Wang, Kefeng; Graf, D.; ...

    2016-03-28

    Here, we report two-dimensional quantum transport and Dirac fermions in BaMnBi 2 single crystals. BaMnBi 2 is a layered bad metal with highly anisotropic conductivity and magnetic order below 290 K. Magnetotransport properties, nonzero Berry phase, small cyclotron mass, and the first-principles band structure calculations indicate the presence of Dirac fermions in Bi square nets. Quantum oscillations in the Hall channel suggest the presence of both electron and hole pockets, whereas Dirac and parabolic states coexist at the Fermi level.

  15. Unconventional pairing symmetry of interacting Dirac fermions on a π -flux lattice

    NASA Astrophysics Data System (ADS)

    Guo, Huaiming; Khatami, Ehsan; Wang, Yao; Devereaux, Thomas P.; Singh, Rajiv R. P.; Scalettar, Richard T.

    2018-04-01

    The pairing symmetry of interacting Dirac fermions on the π -flux lattice is studied with the determinant quantum Monte Carlo and numerical linked-cluster expansion methods. The s*- (i.e., extended s -) and d -wave pairing symmetries, which are distinct in the conventional square lattice, are degenerate under the Landau gauge. We demonstrate that the dominant pairing channel at strong interactions is an unconventional d s* -wave phase consisting of alternating stripes of s*- and d -wave phases. A complementary mean-field analysis shows that while the s*- and d -wave symmetries individually have nodes in the energy spectrum, the d s* channel is fully gapped. The results represent a new realization of pairing in Dirac systems, connected to the problem of chiral d -wave pairing on the honeycomb lattice, which might be more readily accessed by cold-atom experiments.

  16. Unconventional pairing symmetry of interacting Dirac fermions on a π -flux lattice

    DOE PAGES

    Guo, Huaiming; Khatami, Ehsan; Wang, Yao; ...

    2018-04-20

    The pairing symmetry of interacting Dirac fermions on the π-flux lattice is studied with the determinant quantum Monte Carlo and numerical linked-cluster expansion methods. The s*- (i.e., extended s-) and d-wave pairing symmetries, which are distinct in the conventional square lattice, are degenerate under the Landau gauge. We demonstrate that the dominant pairing channel at strong interactions is an unconventional ds*-wave phase consisting of alternating stripes of s*- and d-wave phases. A complementary mean-field analysis shows that while the s*- and d-wave symmetries individually have nodes in the energy spectrum, the ds* channel is fully gapped. The results represent amore » new realization of pairing in Dirac systems, connected to the problem of chiral d-wave pairing on the honeycomb lattice, which might be more readily accessed by cold-atom experiments.« less

  17. Majorana-Based Fermionic Quantum Computation.

    PubMed

    O'Brien, T E; Rożek, P; Akhmerov, A R

    2018-06-01

    Because Majorana zero modes store quantum information nonlocally, they are protected from noise, and have been proposed as a building block for a quantum computer. We show how to use the same protection from noise to implement universal fermionic quantum computation. Our architecture requires only two Majorana modes to encode a fermionic quantum degree of freedom, compared to alternative implementations which require a minimum of four Majorana modes for a spin quantum degree of freedom. The fermionic degrees of freedom support both unitary coupled cluster variational quantum eigensolver and quantum phase estimation algorithms, proposed for quantum chemistry simulations. Because we avoid the Jordan-Wigner transformation, our scheme has a lower overhead for implementing both of these algorithms, allowing for simulation of the Trotterized Hubbard Hamiltonian in O(1) time per unitary step. We finally demonstrate magic state distillation in our fermionic architecture, giving a universal set of topologically protected fermionic quantum gates.

  18. Majorana-Based Fermionic Quantum Computation

    NASA Astrophysics Data System (ADS)

    O'Brien, T. E.; RoŻek, P.; Akhmerov, A. R.

    2018-06-01

    Because Majorana zero modes store quantum information nonlocally, they are protected from noise, and have been proposed as a building block for a quantum computer. We show how to use the same protection from noise to implement universal fermionic quantum computation. Our architecture requires only two Majorana modes to encode a fermionic quantum degree of freedom, compared to alternative implementations which require a minimum of four Majorana modes for a spin quantum degree of freedom. The fermionic degrees of freedom support both unitary coupled cluster variational quantum eigensolver and quantum phase estimation algorithms, proposed for quantum chemistry simulations. Because we avoid the Jordan-Wigner transformation, our scheme has a lower overhead for implementing both of these algorithms, allowing for simulation of the Trotterized Hubbard Hamiltonian in O (1 ) time per unitary step. We finally demonstrate magic state distillation in our fermionic architecture, giving a universal set of topologically protected fermionic quantum gates.

  19. Bootstrapping 3D fermions

    DOE PAGES

    Iliesiu, Luca; Kos, Filip; Poland, David; ...

    2016-03-17

    We study the conformal bootstrap for a 4-point function of fermions in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge C T. We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N. Finally, we also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.

  20. Democratic (s)fermions and lepton flavor violation

    NASA Astrophysics Data System (ADS)

    Hamaguchi, K.; Kakizaki, Mitsuru; Yamaguchi, Masahiro

    2003-09-01

    The democratic approach to account for fermion masses and mixing is known to be successful not only in the quark sector but also in the lepton sector. Here we extend this ansatz to supersymmetric standard models, in which the Kähler potential obeys the underlying S3 flavor symmetries. The requirement of neutrino bi-large mixing angles constrains the form of the Kähler potential for left-handed lepton multiplets. We find that right-handed sleptons can have nondegenerate masses and flavor mixing, while left-handed sleptons are argued to have universal and hence flavor-blind masses. This mass pattern is testable in future collider experiments when superparticle masses will be measured precisely. Lepton flavor violation arises in this scenario. In particular, μ→eγ is expected to be observed in a planned future experiment if supersymmetry breaking scale is close to the weak scale.

  1. Fermion-induced quantum critical points.

    PubMed

    Li, Zi-Xiang; Jiang, Yi-Fan; Jian, Shao-Kai; Yao, Hong

    2017-08-22

    A unified theory of quantum critical points beyond the conventional Landau-Ginzburg-Wilson paradigm remains unknown. According to Landau cubic criterion, phase transitions should be first-order when cubic terms of order parameters are allowed by symmetry in the Landau-Ginzburg free energy. Here, from renormalization group analysis, we show that second-order quantum phase transitions can occur at such putatively first-order transitions in interacting two-dimensional Dirac semimetals. As such type of Landau-forbidden quantum critical points are induced by gapless fermions, we call them fermion-induced quantum critical points. We further introduce a microscopic model of SU(N) fermions on the honeycomb lattice featuring a transition between Dirac semimetals and Kekule valence bond solids. Remarkably, our large-scale sign-problem-free Majorana quantum Monte Carlo simulations show convincing evidences of a fermion-induced quantum critical points for N = 2, 3, 4, 5 and 6, consistent with the renormalization group analysis. We finally discuss possible experimental realizations of the fermion-induced quantum critical points in graphene and graphene-like materials.Quantum phase transitions are governed by Landau-Ginzburg theory and the exceptions are rare. Here, Li et al. propose a type of Landau-forbidden quantum critical points induced by gapless fermions in two-dimensional Dirac semimetals.

  2. Acylation of Chiral Alcohols: A Simple Procedure for Chiral GC Analysis.

    PubMed

    Oromí-Farrús, Mireia; Torres, Mercè; Canela, Ramon

    2012-01-01

    The use of iodine as a catalyst and either acetic or trifluoroacetic acid as a derivatizing reagent for determining the enantiomeric composition of acyclic and cyclic aliphatic chiral alcohols was investigated. Optimal conditions were selected according to the molar ratio of alcohol to acid, the reaction time, and the reaction temperature. Afterwards, chiral stability of chiral carbons was studied. Although no isomerization was observed when acetic acid was used, partial isomerization was detected with the trifluoroacetic acid. A series of chiral alcohols of a widely varying structural type were then derivatized with acetic acid using the optimal conditions. The resolution of the enantiomeric esters and the free chiral alcohols was measured using a capillary gas chromatograph equipped with a CP Chirasil-DEX CB column. The best resolutions were obtained with 2-pentyl acetates (α = 3.00) and 2-hexyl acetates (α = 1.95). This method provides a very simple and efficient experimental workup procedure for analyzing chiral alcohols by chiral-phase GC.

  3. Chiral Polymers.

    DTIC Science & Technology

    1984-10-01

    regardless of the method of polymerization. The styrene-bead copolymers were packed in HPLC columns, but none were especiall, effective in separating...enantiomers in a racemic mixture. The chiral butyrolactone polymer was coated on silica, but this material did not effect resolution of racemic mixtures in an...been effected utilizing chiral oxazolines3 prompted the initial efforts to synthesize various chiral 2-vinyl- oxazoline monomers for incorporation

  4. Atiyah-Patodi-Singer index from the domain-wall fermion Dirac operator

    NASA Astrophysics Data System (ADS)

    Fukaya, Hidenori; Onogi, Tetsuya; Yamaguchi, Satoshi

    2017-12-01

    The Atiyah-Patodi-Singer (APS) index theorem attracts attention for understanding physics on the surface of materials in topological phases. The mathematical setup for this theorem is, however, not directly related to the physical fermion system, as it imposes on the fermion fields a nonlocal boundary condition known as the "APS boundary condition" by hand, which is unlikely to be realized in the materials. In this work, we attempt to reformulate the APS index in a "physicist-friendly" way for a simple setup with U (1 ) or S U (N ) gauge group on a flat four-dimensional Euclidean space. We find that the same index as APS is obtained from the domain-wall fermion Dirac operator with a local boundary condition, which is naturally given by the kink structure in the mass term. As the boundary condition does not depend on the gauge fields, our new definition of the index is easy to compute with the standard Fujikawa method.

  5. Production of black holes and their angular momentum distribution in models with split fermions

    NASA Astrophysics Data System (ADS)

    Dai, De-Chang; Starkman, Glenn D.; Stojkovic, Dejan

    2006-05-01

    In models with TeV-scale gravity it is expected that mini black holes will be produced in near-future accelerators. On the other hand, TeV-scale gravity is plagued with many problems like fast proton decay, unacceptably large n-n¯ oscillations, flavor changing neutral currents, large mixing between leptons, etc. Most of these problems can be solved if different fermions are localized at different points in the extra dimensions. We study the cross section for the production of black holes and their angular momentum distribution in these models with “split” fermions. We find that, for a fixed value of the fundamental mass scale, the total production cross section is reduced compared with models where all the fermions are localized at the same point in the extra dimensions. Fermion splitting also implies that the bulk component of the black hole angular momentum must be taken into account in studies of the black hole decay via Hawking radiation.

  6. Can a Non-Chiral Object Be Made of Two Identical Chiral Moieties?

    ERIC Educational Resources Information Center

    LeMarechal, Jean Francois

    2008-01-01

    Several pedagogical objects can be used to discuss chirality. Here, we use the cut of an apple to show that the association of identical chiral moieties can form a non-chiral object. Octahedral chirality is used to find situations equivalent to the cut of the apple. (Contains 5 figures.)

  7. Anderson localization in sigma models

    NASA Astrophysics Data System (ADS)

    Bruckmann, Falk; Wellnhofer, Jacob

    2018-03-01

    In QCD above the chiral restoration temperature there exists an Anderson transition in the fermion spectrum from localized to delocalized modes. We investigate whether the same holds for nonlinear sigma models which share properties like dynamical mass generation and asymptotic freedom with QCD. In particular we study the spectra of fermions coupled to (quenched) CP(N-1) configurations at high temperatures. We compare results in two and three space-time dimensions: in two dimensions the Anderson transition is absent, since all fermion modes are localized, while in three dimensions it is present. Our measurements include a more recent observable characterizing level spacings: the distribution of ratios of consecutive level spacings.

  8. Enhanced Chiral Discriminatory van der Waals Interactions Mediated by Chiral Surfaces

    NASA Astrophysics Data System (ADS)

    Barcellona, Pablo; Safari, Hassan; Salam, A.; Buhmann, Stefan Yoshi

    2017-05-01

    We predict a discriminatory interaction between a chiral molecule and an achiral molecule which is mediated by a chiral body. To achieve this, we generalize the van der Waals interaction potential between two ground-state molecules with electric, magnetic, and chiral response to nontrivial environments. The force is evaluated using second-order perturbation theory with an effective Hamiltonian. Chiral media enhance or reduce the free interaction via many-body interactions, making it possible to measure the chiral contributions to the van der Waals force with current technology. The van der Waals interaction is discriminatory with respect to enantiomers of different handedness and could be used to separate enantiomers. We also suggest a specific geometric configuration where the electric contribution to the van der Waals interaction is zero, making the chiral component the dominant effect.

  9. Chiral symmetry and pentaquarks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dmitri Diakonov

    2004-07-01

    Spontaneous chiral symmetry breaking, mesons and baryons are illustrated in the language of the Dirac theory. Various forces acting between quarks inside baryons are discussed. I explain why the naive quark models typically overestimate pentaquark masses by some 500 MeV and why in the fully relativistic approach to baryons pentaquarks turn out to be light. I discuss briefly why it can be easier to produce pentaquarks at low than at high energies.

  10. Temperature-driven massless Kane fermions in HgCdTe crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Teppe, F.; Marcinkiewicz, M.; Krishtopenko, S. S.

    2016-08-30

    It has recently been shown that electronic states in bulk gapless HgCdTe offer another realization of pseudo-relativistic three-dimensional particles in condensed matter systems. These single valley relativistic states, massless Kane fermions, cannot be described by any other relativistic particles. Furthermore, the HgCdTe band structure can be continuously tailored by modifying cadmium content or temperature. At critical concentration or temperature, the bandgap collapses as the system undergoes a semimetal-to-semiconductor topological phase transition between the inverted and normal alignments. Here, using far-infrared magneto-spectroscopy we explore the continuous evolution of band structure of bulk HgCdTe as temperature is tuned across the topological phasemore » transition. We demonstrate that the rest mass of Kane fermions changes sign at critical temperature, whereas their velocity remains constant. The velocity universal value of (1.07±0.05) × 106 m s -1 remains valid in a broad range of temperatures and Cd concentrations, indicating a striking universality of the pseudo-relativistic description of the Kane fermions in HgCdTe.« less

  11. Connected and leading disconnected hadronic light-by-light contribution to the muon anomalous magnetic moment with a physical pion mass

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blum, Thomas; Christ, Norman; Hayakawa, Masashi

    We report a lattice QCD calculation of the hadronic light-by-light contribution to the muon anomalous magnetic moment at a physical pion mass. The calculation includes the connected diagrams and the leading, quark-line-disconnected diagrams. We incorporate algorithmic improvements developed in our previous work. The calculation was performed on the 48 3 × 96 ensemble generated with a physical pion mass and a 5.5 fm spatial extent by the RBC and UKQCD Collaborations using the chiral, domain wall fermion formulation. We find a HLbL μ = 5.35(1.35) × 10 –10, where the error is statistical only. The finite-volume and finite lattice-spacing errorsmore » could be quite large and are the subject of ongoing research. Finally, the omitted disconnected graphs, while expected to give a correction of order 10%, also need to be computed.« less

  12. Connected and leading disconnected hadronic light-by-light contribution to the muon anomalous magnetic moment with a physical pion mass

    DOE PAGES

    Blum, Thomas; Christ, Norman; Hayakawa, Masashi; ...

    2017-01-11

    We report a lattice QCD calculation of the hadronic light-by-light contribution to the muon anomalous magnetic moment at a physical pion mass. The calculation includes the connected diagrams and the leading, quark-line-disconnected diagrams. We incorporate algorithmic improvements developed in our previous work. The calculation was performed on the 48 3 × 96 ensemble generated with a physical pion mass and a 5.5 fm spatial extent by the RBC and UKQCD Collaborations using the chiral, domain wall fermion formulation. We find a HLbL μ = 5.35(1.35) × 10 –10, where the error is statistical only. The finite-volume and finite lattice-spacing errorsmore » could be quite large and are the subject of ongoing research. Finally, the omitted disconnected graphs, while expected to give a correction of order 10%, also need to be computed.« less

  13. Determination of chiral pharmaceuticals and illicit drugs in wastewater and sludge using microwave assisted extraction, solid-phase extraction and chiral liquid chromatography coupled with tandem mass spectrometry.

    PubMed

    Evans, Sian E; Davies, Paul; Lubben, Anneke; Kasprzyk-Hordern, Barbara

    2015-07-02

    This is the first study presenting a multi-residue method allowing for comprehensive analysis of several chiral pharmacologically active compounds (cPACs) including beta-blockers, antidepressants and amphetamines in wastewater and digested sludge at the enantiomeric level. Analysis of both the liquid and solid matrices within wastewater treatment is crucial to being able to carry out mass balance within these systems. The method developed comprises filtration, microwave assisted extraction and solid phase extraction followed by chiral liquid chromatography coupled with tandem mass spectrometry to analyse the enantiomers of 18 compounds within all three matrices. The method was successfully validated for 10 compounds within all three matrices (amphetamine, methamphetamine, MDMA, MDA, venlafaxine, desmethylvenlafaxine, citalopram, metoprolol, propranolol and sotalol), 7 compounds validated for the liquid matrices only (mirtazapine, salbutamol, fluoxetine, desmethylcitalopram, atenolol, ephedrine and pseudoephedrine) and 1 compound (alprenolol) passing the criteria for solid samples only. The method was then applied to wastewater samples; cPACs were found at concentration ranges in liquid matrices of: 1.7 ng L(-1) (metoprolol) - 1321 ng L(-1) (tramadol) in influent,

  14. Phase space methods for Majorana fermions

    NASA Astrophysics Data System (ADS)

    Rushin Joseph, Ria; Rosales-Zárate, Laura E. C.; Drummond, Peter D.

    2018-06-01

    Fermionic phase space representations are a promising method for studying correlated fermion systems. The fermionic Q-function and P-function have been defined using Gaussian operators of fermion annihilation and creation operators. The resulting phase-space of covariance matrices belongs to the symmetry class D, one of the non-standard symmetry classes. This was originally proposed to study mesoscopic normal-metal-superconducting hybrid structures, which is the type of structure that has led to recent experimental observations of Majorana fermions. Under a unitary transformation, it is possible to express these Gaussian operators using real anti-symmetric matrices and Majorana operators, which are much simpler mathematical objects. We derive differential identities involving Majorana fermion operators and an antisymmetric matrix which are relevant to the derivation of the corresponding Fokker–Planck equations on symmetric space. These enable stochastic simulations either in real or imaginary time. This formalism has direct relevance to the study of fermionic systems in which there are Majorana type excitations, and is an alternative to using expansions involving conventional Fermi operators. The approach is illustrated by showing how a linear coupled Hamiltonian as used to study topological excitations can be transformed to Fokker–Planck and stochastic equation form, including dissipation through particle losses.

  15. Chiral matrix model of the semi-QGP in QCD

    DOE PAGES

    Pisarski, Robert D.; Skokov, Vladimir V.

    2016-08-08

    Previously, a matrix model of the region near the transition temperature, in the “semi”quark gluon plasma, was developed for the theory of SU(3) gluons without quarks. In this paper we develop a chiral matrix model applicable to QCD by including dynamical quarks with 2+1 flavors. This requires adding a nonet of scalar fields, with both parities, and coupling these to quarks through a Yukawa coupling, y. Treating the scalar fields in mean field approximation, the effective Lagrangian is computed by integrating out quarks to one loop order. As is standard, the potential for the scalar fields is chosen to bemore » symmetric under the flavor symmetry of SU (3) L × SU(3) R × Z (3) A , except for a term linear in the current quark mass, m qk . In addition, at a nonzero temperature T it is necessary to add a new term, ~ m qk T 2 . The parameters of the gluon part of the matrix model are identical to those for the pure glue theory without quarks. The parameters in the chiral matrix model are fixed by the values, at zero temperature, of the pion decay constant and the masses of the pions, kaons, η , and η' . The temperature for the chiral crossover at T$χ$ = 155 MeV is determined by adjusting the Yukawa coupling y . We find reasonable agreement with the results of numerical simulations on the lattice for the pressure and related quantities. In the chiral limit, besides the divergence in the chiral susceptibility there is also a milder divergence in the susceptibility between the Polyakov loop and the chiral order parameter, with critical exponent β $-$ 1 . We compute derivatives with respect to a quark chemical potential to determine the susceptibilities for baryon number, the $χ$ 2n . Especially sensitive tests are provided by $χ$ 4 $-$ $χ$ 2 and by $χ$ 6 , which changes in sign about T$χ$ . In conclusion, the behavior of the susceptibilities in the chiral matrix model strongly suggests that as the temperature increases from T$χ$ , that the transition to

  16. Chiral plasmonics

    PubMed Central

    Hentschel, Mario; Schäferling, Martin; Duan, Xiaoyang; Giessen, Harald; Liu, Na

    2017-01-01

    We present a comprehensive overview of chirality and its optical manifestation in plasmonic nanosystems and nanostructures. We discuss top-down fabricated structures that range from solid metallic nanostructures to groupings of metallic nanoparticles arranged in three dimensions. We also present the large variety of bottom-up synthesized structures. Using DNA, peptides, or other scaffolds, complex nanoparticle arrangements of up to hundreds of individual nanoparticles have been realized. Beyond this static picture, we also give an overview of recent demonstrations of active chiral plasmonic systems, where the chiral optical response can be controlled by an external stimulus. We discuss the prospect of using the unique properties of complex chiral plasmonic systems for enantiomeric sensing schemes. PMID:28560336

  17. Majorana neutrinos in the seesaw mechanism and Bogoliubov quasiparticles

    NASA Astrophysics Data System (ADS)

    Fujikawa, Kazuo; Tureanu, Anca

    2018-03-01

    The idea that the Majorana neutrino should be identified as a Bogoliubov quasiparticle is applied to the seesaw mechanism for the three generations of neutrinos in the Standard Model. A relativistic analog of the Bogoliubov transformation in the present context is a C P -preserving canonical transformation but modifies charge conjugation properties in such a way that the C-noninvariant fermion number-violating term (condensate) is converted to a Dirac mass term. Puzzling aspects associated with the charge conjugation of chiral Weyl fermions are clarified.

  18. Enantioselectively controlled release of chiral drug (metoprolol) using chiral mesoporous silica materials

    NASA Astrophysics Data System (ADS)

    Guo, Zhen; Du, Yu; Liu, Xianbin; Ng, Siu-Choon; Chen, Yuan; Yang, Yanhui

    2010-04-01

    Chiral porous materials have attracted burgeoning attention on account of their potential applications in many areas, such as enantioseparation, chiral catalysis, chemical sensors and drug delivery. In this report, chiral mesoporous silica (CMS) materials with various pore sizes and structures were prepared using conventional achiral templates (other than chiral surfactant) and a chiral cobalt complex as co-template. The synthesized CMS materials were characterized by x-ray diffraction, nitrogen physisorption, scanning electron microscope and transmission electron microscope. These CMS materials, as carriers, were demonstrated to be able to control the enantioselective release of a representative chiral drug (metoprolol). The release kinetics, as modeled by the power law equation, suggested that the release profiles of metoprolol were remarkably dependent on the pore diameter and pore structure of CMS materials. More importantly, R- and S-enantiomers of metoprolol exhibited different release kinetics on CMS compared to the corresponding achiral mesoporous silica (ACMS), attributable to the existence of local chirality on the pore wall surface of CMS materials. The chirality of CMS materials on a molecular level was further substantiated by vibrational circular dichroism measurements.

  19. Thermal chiral vortical and magnetic waves: New excitation modes in chiral fluids

    DOE PAGES

    Kalaydzhyan, Tigran; Murchikova, Elena

    2017-03-24

    In certain circumstances, chiral (parity-violating) medium can be described hydrodynamically as a chiral fluid with microscopic quantum anomalies. Possible examples of such systems include strongly coupled quark–gluon plasma, liquid helium 3He-A, neutron stars and the Early Universe. Here, we study first-order hy-drodynamics of a chiral fluid on a vortex background and in an external magnetic field. We show that there are two previously undiscovered modes describing heat waves propagating along the vortex and magnetic field. We call them the Thermal Chiral Vortical Wave and Thermal Chiral Magnetic Wave. We also identify known gapless excitations of density (chiral vortical and chiralmore » magnetic waves) and transverse velocity (chiral Alfvén wave). We also demonstrate that the velocity of the chiral vortical wave is zero, when the full hydrodynamic framework is applied, and hence the wave is absent and the excitation reduces to the charge diffusion mode. We also comment on the frame-dependent contributions to the obtained propagation velocities.« less

  20. Chiral supramolecular organization from a sheet-like achiral gel: a study of chiral photoinduction.

    PubMed

    Royes, Jorge; Polo, Víctor; Uriel, Santiago; Oriol, Luis; Piñol, Milagros; Tejedor, Rosa M

    2017-05-31

    Chiral photoinduction in a photoresponsive gel based on an achiral 2D architecture with high geometric anisotropy and low roughness has been investigated. Circularly polarized light (CPL) was used as a chiral source and an azobenzene chromophore was employed as a chiral trigger. The chiral photoinduction was studied by evaluating the preferential excitation of enantiomeric conformers of the azobenzene units. Crystallographic data and density functional theory (DFT) calculations show how chirality is transferred to the achiral azomaterials as a result of the combination of chiral photochemistry and supramolecular interactions. This procedure could be applied to predict and estimate chirality transfer from a chiral physical source to a supramolecular organization using different light-responsive units.

  1. Meson properties at finite temperature in a three flavor nonlocal chiral quark model with Polyakov loop

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Contrera, G. A.; CONICET, Rivadavia 1917, 1033 Buenos Aires; Dumm, D. Gomez

    2010-03-01

    We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with the Polyakov loop. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles and decay constants. The critical temperature is found to be T{sub c{approx_equal}}202 MeV, in better agreement with lattice results than the value recently obtained in the local SU(3) PNJL model. Itmore » is seen that above T{sub c} pseudoscalar meson masses get increased, becoming degenerate with the masses of their chiral partners. The temperatures at which this matching occurs depend on the strange quark composition of the corresponding mesons. The topological susceptibility shows a sharp decrease after the chiral transition, signalling the vanishing of the U(1){sub A} anomaly for large temperatures.« less

  2. Heavy Fermions

    NASA Astrophysics Data System (ADS)

    Sugiyama, K.; Ónuki, Y.

    Recent experimental results of high-field magnetization and de Haas-van Alphen experiments in f-electron systems are presented. The magnetic moment and the electronic state are simultaneously discussed because both properties are connected with each other. The first example is a drastic change of the Fermi surface in the antiferromagnet NdIn3. The second is the metamagnetic transition based on the quadrupolar interaction in PrCu2. The third is the metamagnetic transition in a typical heavy fermion compound CeRu2Si2, together with the heavy fermion uranium compounds such as UPd2Al3, URu2Si2 and UPt3.

  3. Simultaneous enantiomeric analysis of eight pesticides in soils and river sediments by chiral liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhao, Pengfei; Zhao, Jing; Lei, Shuo; Guo, Xingjie; Zhao, Longshan

    2018-08-01

    A rapid and sensitive multi-residue method was developed for the simultaneous quantification of eight chiral pesticides (including diniconazole, metalaxyl, paclobutrazol, epoxiconazole, myclobutanil, hexaconazole, napropamide and isocarbophos) at enantiomeric levels in environmental soils and sediments using chiral liquid chromatography-tandem mass spectrometry based on a combined pretreatment of matrix solid-phase dispersion and dispersive liquid-liquid microextraction (MSPD-DLLME). Under optimized conditions, 0.1 g of solid sample was dispersed with 0.4 g of C18-bonded silica sorbent, and 3 mL of methanol was used for eluting the analytes. The collected eluant was dried and then further purified by DLLME with 550 μL of dichloromethane and 960 μL of acetonitrile as extraction and disperser solvent, respectively. The established method was validated and found to be linear, precise, and accurate over the concentration range of 2-500 ng g -1 for epoxiconazole, paclobutrazol and metalaxyl and 4-500 ng g -1 for isocarbophos, hexaconazole, myclobutanil, diniconazole and napropamide. Recoveries of sixteen enantiomers varied from 87.0 to 104.1% and the relative standard deviations (RSD) were less than 10.1%. Method detection and quantification limits (MDLs and MQLs) varied from 0.22 to 1.54 ng g -1 and from 0.91 to 4.00 ng g -1 , respectively. Finally, the method was successfully applied to analyze the enantiomeric composition of the eight chiral pesticides in environmental solid matrices, which will help better understand the behavior of individual enantiomer and make accurate risk assessment on the ecosystem. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Characterizing optical chirality

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bliokh, Konstantin Y.; Advanced Science Institute, RIKEN, Wako-shi, Saitama 351-0198; Nori, Franco

    We examine the recently introduced measure of chirality of a monochromatic optical field [Y. Tang and A. E. Cohen, Phys. Rev. Lett. 104, 163901 (2010)] using the momentum (plane-wave) representation and helicity basis. Our analysis clarifies the physical meaning of the measure of chirality and unveils its close relation to the polarization helicity, spin angular momentum, energy density, and Poynting energy flow. We derive the operators of the optical chirality and of the corresponding chiral momentum, which acquire remarkably simple forms in the helicity representation.

  5. Warm and cold fermionic dark matter via freeze-in

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Klasen, Michael; Yaguna, Carlos E., E-mail: michael.klasen@uni-muenster.de, E-mail: carlos.yaguna@uni-muenster.de

    2013-11-01

    The freeze-in mechanism of dark matter production provides a simple and intriguing alternative to the WIMP paradigm. In this paper, we analyze whether freeze-in can be used to account for the dark matter in the so-called singlet fermionic model. In it, the SM is extended with only two additional fields, a singlet scalar that mixes with the Higgs boson, and the dark matter particle, a fermion assumed to be odd under a Z{sub 2} symmetry. After numerically studying the generation of dark matter, we analyze the dependence of the relic density with respect to all the free parameters of themore » model. These results are then used to obtain the regions of the parameter space that are compatible with the dark matter constraint. We demonstrate that the observed dark matter abundance can be explained via freeze-in over a wide range of masses extending down to the keV range. As a result, warm and cold dark matter can be obtained in this model. It is also possible to have dark matter masses well above the unitarity bound for WIMPs.« less

  6. Dwarf spheroidal galaxies as degenerate gas of free fermions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Domcke, Valerie; Urbano, Alfredo, E-mail: valerie.domcke@sissa.it, E-mail: alfredo.urbano@sissa.it

    2015-01-01

    In this paper we analyze a simple scenario in which Dark Matter (DM) consists of free fermions with mass m{sub f}. We assume that on galactic scales these fermions are capable of forming a degenerate Fermi gas, in which stability against gravitational collapse is ensured by the Pauli exclusion principle. The mass density of the resulting con figuration is governed by a non-relativistic Lane-Emden equation, thus leading to a universal cored profile that depends only on one free parameter in addition to m{sub f}. After reviewing the basic formalism, we test this scenario against experimental data describing the velocity dispersionmore » of the eight classical dwarf spheroidal galaxies of the Milky Way. We find that, despite its extreme simplicity, the model exhibits a good fit to the data and realistic predictions for the size of DM halos providing that m{sub f}≅ 200 eV. Furthermore, we show that in this setup larger galaxies correspond to the non-degenerate limit of the gas. We propose a concrete realization of this model in which DM is produced non-thermally via inflaton decay. We show that imposing the correct relic abundance and the bound on the free-streaming length constrains the inflation model in terms of inflaton mass, its branching ratio into DM and the reheating temperature.« less

  7. Phases of a fermionic model with chiral condensates and Cooper pairs in 1+1 dimensions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mihaila, Bogdan; Blagoev, Krastan B.; MIND Institute, Albuquerque, New Mexico 87131

    2006-01-01

    We study the phase structure of a 4-fermi model with three bare coupling constants, which potentially has three types of bound states. This model is a generalization of the model discussed previously by [A. Chodos, F. Cooper, W. Mao, H. Minakata, and A. Singh, Phys. Rev. D 61, 045011 (2000).], which contained both chiral condensates and Cooper pairs. For this generalization we find that there are two independent renormalized coupling constants which determine the phase structure at finite density and temperature. We find that the vacuum can be in one of three distinct phases depending on the value of thesemore » two renormalized coupling constants.« less

  8. Hybridation of different chiral separation techniques with ICP-MS detection for the separation and determination of selenomethionine enantiomers: chiral speciation of selenized yeast.

    PubMed

    Méndez, S P; González, E B; Sanz-Medel, A

    2001-05-01

    Enantioseparation and determination of selenomethionine enantiomers in selenized yeast was investigated using chiral separation techniques based on different principles, coupled on-line to inductively coupled plasma mass spectrometry (ICP-MS) for selenium-specific detection. High performance liquid chromatography (HPLC) on a beta-cyclodestrin (beta-CD) column, cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC), gas chromatography (GC) on a Chirasil-L-Val column, and HPLC on a Chirobiotic T column have been investigated as the chiral separation techniques. For HPLC separation on the beta-CD column, and also for CD-MEKC, selenomethionine enantiomers were derivatized with NDA/CN(-). For chiral separation by GC, selenomethionine enantiomers were converted into their N-trifluoroacetyl (TFA)-O-alkyl esters. The developed hybridation methodologies are compared with respect to enantioselectivity, sensitivity and analysis time. The usefulness of the best-suited method [HPLC (Chirobiotic T)-ICP-MS] was demonstrated by its application to the successful chiral speciation of selenium and D-and L-selenomethionine content determination in selenized yeast. Copyright 2001 John Wiley & Sons, Ltd.

  9. Effect of molecular structure of tartrates on chiral recognition of tartrate-boric acid complex chiral selectors in chiral microemulsion electrokinetic chromatography.

    PubMed

    Hu, Shao-Qiang; Chen, Yong-Lei; Zhu, Hua-Dong; Shi, Hai-Jun; Yan, Na; Chen, Xing-Guo

    2010-08-20

    Eight l-tartrates and a d-tartrate with different alcohol moieties were used as chiral oils to prepare chiral microemulsions, which were utilized in conjunction with borate buffer to separate the enantiomers of beta-blockers or structurally related compounds by the chiral microemulsion electrokinetic chromatography (MEEKC) method. Among them, six were found to have a relatively good chiral separation performance and their chiral recognition effect in terms of both enantioselectivity and resolution increases linearly with the number of carbon atoms in the alkyl group of alcohol moiety. The tartrates containing alkyl groups of different structures but the same number of carbon atoms, i.e. one of straight chain and one of branched chain, provide similar enantioseparations. The trend was elucidated according to the changes in the difference of the steric matching between the molecules of two enantiomers and chiral selector. Furthermore, it was demonstrated for the first time that a water insoluble solid compound, di-i-butyl l-tartrate (mp. 73.5 degrees C), can be used as an oil to prepare a stable microemulsion to be used in the chiral MEEKC successfully. And a critical effect of the microemulsion for chiral separation, which has never been reported before, was found in this experiment, namely providing a hydrophobic environment to strengthen the interactions between the chiral selector and enantiomers. Copyright 2010 Elsevier B.V. All rights reserved.

  10. Chiral dynamics in the low-temperature phase of QCD

    NASA Astrophysics Data System (ADS)

    Brandt, Bastian B.; Francis, Anthony; Meyer, Harvey B.; Robaina, Daniel

    2014-09-01

    We investigate the low-temperature phase of QCD and the crossover region with two light flavors of quarks. The chiral expansion around the point (T,m=0) in the temperature vs quark-mass plane indicates that a sharp real-time excitation exists with the quantum numbers of the pion. An exact sum rule is derived for the thermal modification of the spectral function associated with the axial charge density; the (dominant) pion pole contribution obeys the sum rule. We determine the two parameters of the pion dispersion relation using lattice QCD simulations and test the applicability of the chiral expansion. The time-dependent correlators are also analyzed using the maximum entropy method, yielding consistent results. Finally, we test the predictions of the chiral expansion around the point (T=0,m=0) for the temperature dependence of static observables.

  11. Static weak dipole moments of the τ lepton via renormalizable scalar leptoquark interactions

    NASA Astrophysics Data System (ADS)

    Bolaños, A.; Moyotl, A.; Tavares-Velasco, G.

    2014-03-01

    The weak dipole moments of elementary fermions are calculated at the one-loop level in the framework of a renormalizable scalar leptoquark model that forbids baryon number violating processes and so is free from the strong constraints arising from experimental data. In this model there are two scalar leptoquarks accommodated in a SUL(2)×UY(1) doublet: One of these leptoquarks is nonchiral and has electric charge of 5/3e, whereas the other one is chiral and has electric charge 2/3e. In particular, a nonchiral leptoquark contributes to the weak properties of an up fermion via a chirality-flipping term proportional to the mass of the virtual fermion, and can also induce a nonzero weak electric dipole moment provided that the leptoquark couplings are complex. The numerical analysis is focused on the weak properties of the τ lepton since they offer good prospects for experimental study. The constraints on leptoquark couplings are briefly discussed for a nonchiral leptoquark with nondiagonal couplings to the second and third fermion generations, a third-generation nonchiral leptoquark, and a third-generation chiral leptoquark. It is found that although the chirality-flipping term can enhance the weak properties of the τ lepton via the top quark contribution, such an enhancement would be offset by the strong constraints on the leptoquark couplings. So, the contribution of scalar leptoquarks to the weak magnetic dipole moment of the τ lepton are smaller than the standard model (SM) contributions but can be of similar size to those arising in some SM extensions. A nonchiral leptoquark can also give contributions to the weak electric dipole moment larger than the SM one but well below the experimental limit. We also discuss the case of the off-shell weak dipole moments and, for completeness, analyze the behavior of the τ electromagnetic properties.

  12. Chiral symmetry constraints on resonant amplitudes

    NASA Astrophysics Data System (ADS)

    Bruns, Peter C.; Mai, Maxim

    2018-03-01

    We discuss the impact of chiral symmetry constraints on the quark-mass dependence of meson resonance pole positions, which are encoded in non-perturbative parametrizations of meson scattering amplitudes. Model-independent conditions on such parametrizations are derived, which are shown to guarantee the correct functional form of the leading quark-mass corrections to the resonance pole positions. Some model amplitudes for ππ scattering, widely used for the determination of ρ and σ resonance properties from results of lattice simulations, are tested explicitly with respect to these conditions.

  13. Fermion systems in discrete space-time

    NASA Astrophysics Data System (ADS)

    Finster, Felix

    2007-05-01

    Fermion systems in discrete space-time are introduced as a model for physics on the Planck scale. We set up a variational principle which describes a non-local interaction of all fermions. This variational principle is symmetric under permutations of the discrete space-time points. We explain how for minimizers of the variational principle, the fermions spontaneously break this permutation symmetry and induce on space-time a discrete causal structure.

  14. Superfluid response in heavy fermion superconductors

    NASA Astrophysics Data System (ADS)

    Zhong, Yin; Zhang, Lan; Shao, Can; Luo, Hong-Gang

    2017-10-01

    Motivated by a recent London penetration depth measurement [H. Kim, et al., Phys. Rev. Lett. 114, 027003 (2015)] and novel composite pairing scenario [O. Erten, R. Flint, and P. Coleman, Phys. Rev. Lett. 114, 027002 (2015)] of the Yb-doped heavy fermion superconductor CeCoIn5, we revisit the issue of superfluid response in the microscopic heavy fermion lattice model. However, from the literature, an explicit expression for the superfluid response function in heavy fermion superconductors is rare. In this paper, we investigate the superfluid density response function in the celebrated Kondo-Heisenberg model. To be specific, we derive the corresponding formalism from an effective fermionic large- N mean-field pairing Hamiltonian whose pairing interaction is assumed to originate from the effective local antiferromagnetic exchange interaction. Interestingly, we find that the physically correct, temperature-dependent superfluid density formula can only be obtained if the external electromagnetic field is directly coupled to the heavy fermion quasi-particle rather than the bare conduction electron or local moment. Such a unique feature emphasizes the key role of the Kondo-screening-renormalized heavy quasi-particle for low-temperature/energy thermodynamics and transport behaviors. As an important application, the theoretical result is compared to an experimental measurement in heavy fermion superconductors CeCoIn5 and Yb-doped Ce1- x Yb x CoIn5 with fairly good agreement and the transition of the pairing symmetry in the latter material is explained as a simple doping effect. In addition, the requisite formalism for the commonly encountered nonmagnetic impurity and non-local electrodynamic effect are developed. Inspired by the success in explaining classic 115-series heavy fermion superconductors, we expect the present theory will be applied to understand other heavy fermion superconductors such as CeCu2Si2 and more generic multi-band superconductors.

  15. The topological susceptibility from grand canonical simulations in the interacting instanton liquid model: Chiral phase transition and axion mass

    NASA Astrophysics Data System (ADS)

    Wantz, Olivier; Shellard, E. P. S.

    2010-04-01

    This is the last in a series of papers on the topological susceptibility in the interacting instanton liquid model (IILM). We will derive improved finite temperature interactions to study the thermodynamic limit of grand canonical Monte Carlo simulations in the quenched and unquenched case with light, physical quark masses. In particular, we will be interested in chiral symmetry breaking. The paper culminates by giving, for the first time, a well-motivated temperature-dependent axion mass. Especially, this work finally provides a computation of the axion mass in the low temperature regime, ma2fa2=1.46×10-3Λ41+0.50 T/Λ1+(3.53 . It connects smoothly to the high temperature dilute gas approximation; the latter is improved by including quark threshold effects. To compare with earlier studies, we also provide the usual power-law ma2=αΛ4fa2(T, where Λ=400 MeV, n=6.68 and α=1.68×10-7.

  16. Multiscale Monte Carlo equilibration: Two-color QCD with two fermion flavors

    DOE PAGES

    Detmold, William; Endres, Michael G.

    2016-12-02

    In this study, we demonstrate the applicability of a recently proposed multiscale thermalization algorithm to two-color quantum chromodynamics (QCD) with two mass-degenerate fermion flavors. The algorithm involves refining an ensemble of gauge configurations that had been generated using a renormalization group (RG) matched coarse action, thereby producing a fine ensemble that is close to the thermalized distribution of a target fine action; the refined ensemble is subsequently rethermalized using conventional algorithms. Although the generalization of this algorithm from pure Yang-Mills theory to QCD with dynamical fermions is straightforward, we find that in the latter case, the method is susceptible tomore » numerical instabilities during the initial stages of rethermalization when using the hybrid Monte Carlo algorithm. We find that these instabilities arise from large fermion forces in the evolution, which are attributed to an accumulation of spurious near-zero modes of the Dirac operator. We propose a simple strategy for curing this problem, and demonstrate that rapid thermalization--as probed by a variety of gluonic and fermionic operators--is possible with the use of this solution. Also, we study the sensitivity of rethermalization rates to the RG matching of the coarse and fine actions, and identify effective matching conditions based on a variety of measured scales.« less

  17. Quantum Gas Microscope for Fermionic Atoms

    NASA Astrophysics Data System (ADS)

    Okan, Melih; Cheuk, Lawrence; Nichols, Matthew; Lawrence, Katherine; Zhang, Hao; Zwierlein, Martin

    2016-05-01

    Strongly interacting fermions define the properties of complex matter throughout nature, from atomic nuclei and modern solid state materials to neutron stars. Ultracold atomic Fermi gases have emerged as a pristine platform for the study of many-fermion systems. In this poster we demonstrate the realization of a quantum gas microscope for fermionic 40 K atoms trapped in an optical lattice and the recent experiments which allows one to probe strongly correlated fermions at the single atom level. We combine 3D Raman sideband cooling with high- resolution optics to simultaneously cool and image individual atoms with single lattice site resolution at a detection fidelity above 95%. The imaging process leaves the atoms predominantly in the 3D motional ground state of their respective lattice sites, inviting the implementation of a Maxwell's demon to assemble low-entropy many-body states. Single-site resolved imaging of fermions enables the direct observation of magnetic order, time resolved measurements of the spread of particle correlations, and the detection of many-fermion entanglement. NSF, AFOSR-PECASE, AFOSR-MURI on Exotic Phases of Matter, ARO-MURI on Atomtronics, ONR, a Grant from the Army Research Office with funding from the DARPA OLE program, and the David and Lucile Packard Foundation.

  18. Scalar versus fermionic top partner interpretations of toverline{t}+{E}_T^{miss} searches at the LHC

    NASA Astrophysics Data System (ADS)

    Kraml, Sabine; Laa, Ursula; Panizzi, Luca; Prager, Hugo

    2016-11-01

    We assess how different ATLAS and CMS searches for supersymmetry in the toverline{t}+{E}_T^{miss} final state at Run 1 of the LHC constrain scenarios with a fermionic top partner and a dark matter candidate. We find that the efficiencies of these searches in all-hadronic, 1-lepton and 2-lepton channels are quite similar for scalar and fermionic top partners. Therefore, in general, efficiency maps for stop-neutralino simplified models can also be applied to fermionic top-partner models, provided the narrow width approximation holds in the latter. Owing to the much higher production cross-sections of heavy top quarks as compared to stops, masses up to m T ≈ 850 GeV can be excluded from the Run 1 stop searches. Since the simplified-model results published by ATLAS and CMS do not extend to such high masses, we provide our own efficiency maps obtained with C heckMATE and M adA nalysis 5 for these searches. Finally, we also discuss how generic gluino/squark searches in multi-jet final states constrain heavy top partner production.

  19. Silver Films with Hierarchical Chirality.

    PubMed

    Ma, Liguo; Cao, Yuanyuan; Duan, Yingying; Han, Lu; Che, Shunai

    2017-07-17

    Physical fabrication of chiral metallic films usually results in singular or large-sized chirality, restricting the optical asymmetric responses to long electromagnetic wavelengths. The chiral molecule-induced formation of silver films prepared chemically on a copper substrate through a redox reaction is presented. Three levels of chirality were identified: primary twisted nanoflakes with atomic crystal lattices, secondary helical stacking of these nanoflakes to form nanoplates, and tertiary micrometer-sized circinates consisting of chiral arranged nanoplates. The chiral Ag films exhibited multiple plasmonic absorption- and scattering-based optical activities at UV/Vis wavelengths based on their hierarchical chirality. The Ag films showed chiral selectivity for amino acids in catalytic electrochemical reactions, which originated from their primary atomic crystal lattices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Magnetic Majorana Fermions

    NASA Astrophysics Data System (ADS)

    Moessner, Roderich

    Condensed matter systems provide emergent mini-universes in which quasiparticles may exist which do not correspond to any experimentally detected elementary particle. Topological quantum materials have been particularly productive in this regard, with the present search focussing on Majorana fermions, known theoretically already for decades. Here, we discuss manifestations of magnetic Majorana fermions in the Kitaev model. We place particular emphasis on their fate when perturbations, such as Heisenberg terms, are added to the ideal model system, and address experimental signatures of their vestiges in phases adjacent to the spin liquid.

  1. Roper resonance and S11(1535) from lattice QCD

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    N. Mathur; Y. Chen; S.J. Dong

    2005-01-06

    Using the constrained curve fitting method and overlap fermions with the lowest pion mass at 180 MeV, we observe that the masses of the first positive and negative parity excited states of the nucleon tend to cross over as the quark masses are taken to the chiral limit. Both results at the physical pion mass agree with the experimental values of the Roper resonance (N{sup 1/2+} (1440)) and S{sub 11} (N{sup 1/2-}(1535)). This is seen for the first time in a lattice QCD calculation. These results are obtained on a quenched Iwasaki 16{sup 3} x 28 lattice with a =more » 0.2 fm. We also extract the ghost {eta}{prime} N states (a quenched artifact) which are shown to decouple from the nucleon interpolation field above m{sub {pi}} {approx} 300 MeV. From the quark mass dependence of these states in the chiral region, we conclude that spontaneously broken chiral symmetry dictates the dynamics of light quarks in the nucleon.« less

  2. The phi-meson and Chiral-mass-meson production in heavy-ion collisions as potential probes of quark-gluon-plasma and Chiral symmetry transitions

    NASA Technical Reports Server (NTRS)

    Takahashi, Y.; Eby, P. B.

    1985-01-01

    Possibilities of observing abundances of phi mesons and narrow hadronic pairs, as results of QGP and Chiral transitions, are considered for nucleus-nucleus interactions. Kinematical requirements in forming close pairs are satisfied in K+K decays of S(975) and delta (980) mesons with small phi, and phi (91020) mesons with large PT, and in pi-pi decays of familiar resonance mesons only in a partially restored chiral symmetry. Gluon-gluon dominance in QGP can enhance phi meson production. High hadronization rates of primordial resonance mesons which form narrow hadronic pairs are not implausible. Past cosmic ray evidences of anomalous phi production and narrow pair abundances are considered.

  3. Pion-nucleon scattering in covariant baryon chiral perturbation theory with explicit Delta resonances

    NASA Astrophysics Data System (ADS)

    Yao, De-Liang; Siemens, D.; Bernard, V.; Epelbaum, E.; Gasparyan, A. M.; Gegelia, J.; Krebs, H.; Meißner, Ulf-G.

    2016-05-01

    We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz invariant formulation of baryon chiral perturbation theory using dimensional regularization and the extended on-mass-shell renormalization scheme. In the delta resonance sector, the on mass-shell renormalization is realized as a complex-mass scheme. By fitting the low-energy constants of the effective Lagrangian to the S- and P -partial waves a satisfactory description of the phase shifts from the analysis of the Roy-Steiner equations is obtained. We predict the phase shifts for the D and F waves and compare them with the results of the analysis of the George Washington University group. The threshold parameters are calculated both in the delta-less and delta-full cases. Based on the determined low-energy constants, we discuss the pion-nucleon sigma term. Additionally, in order to determine the strangeness content of the nucleon, we calculate the octet baryon masses in the presence of decuplet resonances up to next-to-next-to-leading order in SU(3) baryon chiral perturbation theory. The octet baryon sigma terms are predicted as a byproduct of this calculation.

  4. Matrix elements of Δ B =0 operators in heavy hadron chiral perturbation theory

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Wan

    2015-05-01

    We study the light-quark mass and spatial volume dependence of the matrix elements of Δ B =0 four-quark operators relevant for the determination of Vu b and the lifetime ratios of single-b hadrons. To this end, one-loop diagrams are computed in the framework of heavy hadron chiral perturbation theory with partially quenched formalism for three light-quark flavors in the isospin limit; flavor-connected and -disconnected diagrams are carefully analyzed. These calculations include the leading light-quark flavor and heavy-quark spin symmetry breaking effects in the heavy hadron spectrum. Our results can be used in the chiral extrapolation of lattice calculations of the matrix elements to the physical light-quark masses and to infinite volume. To provide insight on such chiral extrapolation, we evaluate the one-loop contributions to the matrix elements containing external Bd, Bs mesons and Λb baryon in the QCD limit, where sea and valence quark masses become equal. In particular, we find that the matrix elements of the λ3 flavor-octet operators with an external Bd meson receive the contributions solely from connected diagrams in which current lattice techniques are capable of precise determination of the matrix elements. Finite volume effects are at most a few percent for typical lattice sizes and pion masses.

  5. Phenomenology of fermion production during axion inflation

    NASA Astrophysics Data System (ADS)

    Adshead, Peter; Pearce, Lauren; Peloso, Marco; Roberts, Michael A.; Sorbo, Lorenzo

    2018-06-01

    We study the production of fermions through a derivative coupling with a pseudoscalar inflaton and the effects of the produced fermions on the scalar primordial perturbations. We present analytic results for the modification of the scalar power spectrum due to the produced fermions, and we estimate the amplitude of the non-Gaussianities in the equilateral regime. Remarkably, we find a regime where the effect of the fermions gives the dominant contribution to the scalar spectrum while the amplitude of the bispectrum is small and in agreement with observation. We also note the existence of a regime in which the backreaction of the fermions on the evolution of the zero-mode of the inflaton can lead to inflation even if the potential of the inflaton is steep and does not satisfy the slow-roll conditions.

  6. Induction of Chirality in Two-Dimensional Nanomaterials: Chiral 2D MoS2 Nanostructures.

    PubMed

    Purcell-Milton, Finn; McKenna, Robert; Brennan, Lorcan J; Cullen, Conor P; Guillemeney, Lilian; Tepliakov, Nikita V; Baimuratov, Anvar S; Rukhlenko, Ivan D; Perova, Tatiana S; Duesberg, Georg S; Baranov, Alexander V; Fedorov, Anatoly V; Gun'ko, Yurii K

    2018-02-27

    Two-dimensional (2D) nanomaterials have been intensively investigated due to their interesting properties and range of potential applications. Although most research has focused on graphene, atomic layered transition metal dichalcogenides (TMDs) and particularly MoS 2 have gathered much deserved attention recently. Here, we report the induction of chirality into 2D chiral nanomaterials by carrying out liquid exfoliation of MoS 2 in the presence of chiral ligands (cysteine and penicillamine) in water. This processing resulted in exfoliated chiral 2D MoS 2 nanosheets showing strong circular dichroism signals, which were far past the onset of the original chiral ligand signals. Using theoretical modeling, we demonstrated that the chiral nature of MoS 2 nanosheets is related to the presence of chiral ligands causing preferential folding of the MoS 2 sheets. There was an excellent match between the theoretically calculated and experimental spectra. We believe that, due to their high aspect ratio planar morphology, chiral 2D nanomaterials could offer great opportunities for the development of chiroptical sensors, materials, and devices for valleytronics and other potential applications. In addition, chirality plays a key role in many chemical and biological systems, with chiral molecules and materials critical for the further development of biopharmaceuticals and fine chemicals, and this research therefore should have a strong impact on relevant areas of science and technology such as nanobiotechnology, nanomedicine, and nanotoxicology.

  7. Fermionic topological quantum states as tensor networks

    NASA Astrophysics Data System (ADS)

    Wille, C.; Buerschaper, O.; Eisert, J.

    2017-06-01

    Tensor network states, and in particular projected entangled pair states, play an important role in the description of strongly correlated quantum lattice systems. They do not only serve as variational states in numerical simulation methods, but also provide a framework for classifying phases of quantum matter and capture notions of topological order in a stringent and rigorous language. The rapid development in this field for spin models and bosonic systems has not yet been mirrored by an analogous development for fermionic models. In this work, we introduce a tensor network formalism capable of capturing notions of topological order for quantum systems with fermionic components. At the heart of the formalism are axioms of fermionic matrix-product operator injectivity, stable under concatenation. Building upon that, we formulate a Grassmann number tensor network ansatz for the ground state of fermionic twisted quantum double models. A specific focus is put on the paradigmatic example of the fermionic toric code. This work shows that the program of describing topologically ordered systems using tensor networks carries over to fermionic models.

  8. Production of a Scalar Boson and a Fermion Pair in Arbitrarily Polarized e - e + Beams

    NASA Astrophysics Data System (ADS)

    Abdullayev, S. K.; Gojayev, M. Sh.; Nasibova, N. A.

    2018-05-01

    Within the framework of the Standard Model (Minimal Supersymmetric Standard Model) we consider the production of the scalar boson HSM (h; H) and a fermion pair ff- in arbitrarily polarized, counterpropagating electron-positron beams e - e + ⇒ HSM (h; H) ff-. Characteristic features of the behavior of the cross sections and polarization characteristics (right-left spin asymmetry, degree of longitudinal polarization of the fermion, and transverse spin asymmetry) are investigated and elucidated as functions of the energy of the electron-positron beams and the mass of the scalar boson.

  9. Pion-nucleon scattering: from chiral perturbation theory to Roy-Steiner equations

    NASA Astrophysics Data System (ADS)

    Kubis, Bastian; Hoferichter, Martin; de Elvira, Jacobo Ruiz; Meißner, Ulf-G.

    2016-11-01

    Ever since Weinberg's seminal predictions of the pion-nucleon scattering amplitudes at threshold, this process has been of central interest for the study of chiral dynamics involving nucleons. The scattering lengths or the pion-nucleon σ-term are fundamental quantities characterizing the explicit breaking of chiral symmetry by means of the light quark masses. On the other hand, pion-nucleon dynamics also strongly affects the long-range part of nucleon-nucleon potentials, and hence has a far-reaching impact on nuclear physics. We discuss the fruitful combination of dispersion-theoretical methods, in the form of Roy-Steiner equations, with chiral dynamics to determine pion-nucleon scattering amplitudes at low energies with high precision.*

  10. Fermion Superfluidity

    NASA Technical Reports Server (NTRS)

    Strecker, Kevin; Truscott, Andrew; Partridge, Guthrie; Chen, Ying-Cheng

    2003-01-01

    Dual evaporation gives 50 million fermions at T = 0.1 T(sub F). Demonstrated suppression of interactions by coherent superposition - applicable to atomic clocks. Looking for evidence of Cooper pairing and superfluidity.

  11. Periodic chiral structures

    NASA Technical Reports Server (NTRS)

    Jaggard, Dwight L.; Engheta, Nader; Pelet, Philippe; Liu, John C.; Kowarz, Marek W.; Kim, Yunjin

    1989-01-01

    The electromagnetic properties of a structure that is both chiral and periodic are investigated using coupled-mode equations. The periodicity is described by a sinusoidal perturbation of the permittivity, permeability, and chiral admittance. The coupled-mode equations are derived from physical considerations and used to examine bandgap structure and reflected and transmitted fields. Chirality is observed predominantly in transmission, whereas periodicity is present in both reflection and transmission.

  12. Lattice QCD calculations of nucleon transverse momentum-dependent parton distributions using clover and domain wall fermions

    DOE PAGES

    Yoon, Boram; Bhattacharya, Tanmoy; Gupta, Rajan; ...

    2015-01-01

    Here, we present a lattice QCD calculation of transverse momentum dependent parton distribution functions (TMDs) of protons using staple-shaped Wilson lines. For time-reversal odd observables, we calculate the generalized Sivers and Boer-Mulders transverse momentum shifts in SIDIS and DY cases, and for T-even observables we calculate the transversity related to the tensor charge and the generalized worm-gear shift. The calculation is done on two different n f = 2+1 ensembles: domain-wall fermion (DWF) with lattice spacing 0:084fm and pion mass of 297 MeV, and clover fermion with lattice spacing 0:114 fm and pion mass of 317 MeV. The results frommore » those two different discretizations are consistent with each other.« less

  13. Ghost free systems with coexisting bosons and fermions

    NASA Astrophysics Data System (ADS)

    Kimura, Rampei; Sakakihara, Yuki; Yamaguchi, Masahide

    2017-08-01

    We study the coexistence system of both bosonic and fermionic degrees of freedom. Even if a Lagrangian does not include higher derivatives, fermionic ghosts exist. For a Lagrangian with up to first derivatives, we find the fermionic ghost free condition in Hamiltonian analysis, which is found to be the same as requiring that the equations of motion of fermions be first order in Lagrangian formulation. When fermionic degrees of freedom are present, the uniqueness of time evolution is not guaranteed a priori because of the Grassmann property. We confirm that the additional condition, which is introduced to close Hamiltonian analysis, also ensures the uniqueness of the time evolution of the system.

  14. Chirality in adsorption on solid surfaces.

    PubMed

    Zaera, Francisco

    2017-12-07

    In the present review we survey the main advances made in recent years on the understanding of chemical chirality at solid surfaces. Chirality is an important topic, made particularly relevant by the homochiral nature of the biochemistry of life on Earth, and many chiral chemical reactions involve solid surfaces. Here we start our discussion with a description of surface chirality and of the different ways that chirality can be bestowed on solid surfaces. We then expand on the studies carried out to date to understand the adsorption of chiral compounds at a molecular level. We summarize the work published on the adsorption of pure enantiomers, of enantiomeric mixtures, and of prochiral molecules on chiral and achiral model surfaces, especially on well-defined metal single crystals but also on other flat substrates such as highly ordered pyrolytic graphite. Several phenomena are identified, including surface reconstruction and chiral imprinting upon adsorption of chiral agents, and the enhancement or suppression of enantioselectivity seen in some cases upon adsorption of enantiomixtures of chiral compounds. The possibility of enhancing the enantiopurity of adsorbed layers upon the addition of chiral seeds and the so-called "sergeants and soldiers" phenomenon are presented. Examples are provided where the chiral behavior has been associated with either thermodynamic or kinetic driving forces. Two main approaches to the creation of enantioselective surface sites are discussed, namely, via the formation of supramolecular chiral ensembles made out of small chiral adsorbates, and by adsorption of more complex chiral molecules capable of providing suitable chiral environments for reactants by themselves, via the formation of individual adsorbate:modifier adducts on the surface. Finally, a discussion is offered on the additional effects generated by the presence of the liquid phase often required in practical applications such as enantioselective crystallization, chiral

  15. Chirality in molecular collision dynamics

    NASA Astrophysics Data System (ADS)

    Lombardi, Andrea; Palazzetti, Federico

    2018-02-01

    Chirality is a phenomenon that permeates the natural world, with implications for atomic and molecular physics, for fundamental forces and for the mechanisms at the origin of the early evolution of life and biomolecular homochirality. The manifestations of chirality in chemistry and biochemistry are numerous, the striking ones being chiral recognition and asymmetric synthesis with important applications in molecular sciences and in industrial and pharmaceutical chemistry. Chiral discrimination phenomena, due to the existence of two enantiomeric forms, very well known in the case of interaction with light, but still nearly disregarded in molecular collision studies. Here we review some ideas and recent advances about the role of chirality in molecular collisions, designing and illustrating molecular beam experiments for the demonstration of chiral effects and suggesting a scenario for a stereo-directional origin of chiral selection.

  16. Enantioselective analysis of triazole fungicide myclobutanil in cucumber and soil under different application modes by chiral liquid chromatography/tandem mass spectrometry.

    PubMed

    Dong, Fengshou; Cheng, Li; Liu, Xingang; Xu, Jun; Li, Jing; Li, Yuanbo; Kong, Zhiqiang; Jian, Qiu; Zheng, Yongquan

    2012-02-29

    A sensitive and enantioselective method was developed and validated for the determination of myclobutanil enantiomers by chiral liquid chromatography coupled with tandem mass spectrometry. The separation and determination were performed using reversed-phase chromatography on a Chiralcel OD-RH column, with ACN-water (70/30, v/v) as the mobile phase under isocratic conditions at 0.5 mL/min flow rate. The matrix effect, linearity, precision, accuracy, and stability were evaluated. The proposed method then was successfully applied to the study of enantioselective degradation of rac-myclobutanil in cucumber and soil under different application modes. The results showed that the preferential degradation of (+)-myclobutanil resulted in an enrichment of the (-)-myclobutanil residue in plant and soil. Moreover, in cucumber, the stereoselective intensity of myclobutanil under root douche treatment was stronger than that under foliar spraying treatment, whereas in soil, the intensity was exactly opposite. The probable reasons underlying these enantioselective effects were also discussed. This study highlighted the importance of examining the fate of both enantiomers in the greenhouse system for the correct use of chiral pesticides.

  17. Direct observation of how the heavy-fermion state develops in CeCoIn5

    NASA Astrophysics Data System (ADS)

    Chen, Q. Y.; Xu, D. F.; Niu, X. H.; Jiang, J.; Peng, R.; Xu, H. C.; Wen, C. H. P.; Ding, Z. F.; Huang, K.; Shu, L.; Zhang, Y. J.; Lee, H.; Strocov, V. N.; Shi, M.; Bisti, F.; Schmitt, T.; Huang, Y. B.; Dudin, P.; Lai, X. C.; Kirchner, S.; Yuan, H. Q.; Feng, D. L.

    2017-07-01

    Heavy-fermion systems share some of the strange metal phenomenology seen in other unconventional superconductors, providing a unique opportunity to set strange metals in a broader context. Central to understanding heavy-fermion systems is the interplay of localization and itinerancy. These materials acquire high electronic masses and a concomitant Fermi volume increase as the f electrons delocalize at low temperatures. However, despite the wide-spread acceptance of this view, a direct microscopic verification has been lacking. Here we report high-resolution angle-resolved photoemission measurements on CeCoIn5, a prototypical heavy-fermion compound, which spectroscopically resolve the development of band hybridization and the Fermi surface expansion over a wide temperature region. Unexpectedly, the localized-to-itinerant transition occurs at surprisingly high temperatures, yet f electrons are still largely localized even at the lowest temperature. These findings point to an unanticipated role played by crystal-field excitations in the strange metal behavior of CeCoIn5. Our results offer a comprehensive experimental picture of the heavy-fermion formation, setting the stage for understanding the emergent properties, including unconventional superconductivity, in this and related materials.

  18. Photoremovable chiral auxiliary.

    PubMed

    Kammath, Viju Balachandran; Sebej, Peter; Slanina, Tomáš; Kříž, Zdeněk; Klán, Petr

    2012-03-01

    A new concept of a photoremovable chiral auxiliary (PCA), based on the chiral benzoin chromophore, is introduced. This moiety can control the asymmetric formation of a Diels-Alder adduct, and then be removed in a subsequent photochemical step in high chemical and quantum yields. Selective formation of the products at up to 96% ee was observed in the presence of a Lewis acid catalyst in the case of a 2-methoxybenzoinyl chiral auxiliary.

  19. Cosmological baryon and lepton number in the presence of electroweak fermion-number violation

    NASA Technical Reports Server (NTRS)

    Harvey, Jeffrey A.; Turner, Michael S.

    1990-01-01

    In the presence of rapid fermion-number violation due to nonperturbative electroweak effects certain relations between the baryon number of the Universe and the lepton numbers of the Universe are predicted. In some cases the electron-neutrino asymmetry is exactly specified in terms of the baryon asymmetry. Without introducing new particles, beyond the usual quarks and leptons, it is necessary that the Universe possess a nonzero value of B - L prior to the epoch of fermion-number violation if baryon and lepton asymmetries are to survive. Contrary to intuition, even though electroweak processes violate B + L, a nonzero value of B + L persists after the epoch of rapid fermion-number violation. If the standard model is extended to include lepton-number violation, for example through Majorana neutrino masses, then electroweak processes will reduce the baryon number to zero even in the presence of an initial B - L unless 20 M(sub L) approximately greater than the square root of (T(sub B - L) m(sub P1)) where M(sub L) sets the scale of lepton number violation and T(sub B - L) is the temperature at which a B - L asymmetry is produced. In many models this implies that neutrinos must be so light that they cannot contribute appreciably to the mass density of the Universe.

  20. B+ L violation at colliders and new physics

    NASA Astrophysics Data System (ADS)

    Cerdeño, David G.; Reimitz, Peter; Sakurai, Kazuki; Tamarit, Carlos

    2018-04-01

    Chiral electroweak anomalies predict baryon ( B) and lepton ( L) violating fermion interactions, which can be dressed with large numbers of Higgs and gauge bosons. The estimation of the total B + L-violating rate from an initial two-particle state — potentially observable at colliders — has been the subject of an intense discussion, mainly centered on the resummation of boson emission, which is believed to contribute to the cross-section with an exponential function of the energy, yet with an exponent (the "holy-grail" function) which is not fully known in the energy range of interest. In this article we focus instead on the effect of fermions beyond the Standard-Model (SM) in the polynomial contributions to the rate. It is shown that B + L processes involving the new fermions have a polynomial contribution that can be several orders of magnitude greater than in the SM, for high centre-of-mass energies and light enough masses. We also present calculations that hint at a simple dependence of the holy grail function on the heavy fermion masses. Thus, if anomalous B + L violating interactions are ever detected at high-energy colliders, they could be associated with new physics.

  1. Superalgebra and fermion-boson symmetry

    PubMed Central

    Miyazawa, Hironari

    2010-01-01

    Fermions and bosons are quite different kinds of particles, but it is possible to unify them in a supermultiplet, by introducing a new mathematical scheme called superalgebra. In this article we discuss the development of the concept of symmetry, starting from the rotational symmetry and finally arriving at this fermion-boson (FB) symmetry. PMID:20228617

  2. New thermotropic chiral nematic polymers. 3. Copolymers containing a cyanobiphenyl group and (S)-(-)-1-phenylethanol or (S)-(-)-1-phenylethylamine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mastrangelo, J.C.; Chen, S.H.

    Thermotropic chiral nematics in thin films on the order of 10 [mu]m possess a unique optical property, selective wavelength reflection, that forms the basis of a number of potential applications including circular polarizers, notch filters, beamsplitters, and so on. Instead of low molar mass chiral nematics, thermotropic copolymers have been actively pursued as an alternative in view of the possibility of achieving long-term mesophase stability and optical characteristics desired for passive device applications. Cyanobiphenyl is a relatively high birefringent group which is known to contribute to the formation of low molar mass liquid crystals; it was found to exhibit amore » nematic mesophase between the glass transition and clearing temperatures in side-chain polyacrylates with spacer lengths in the 2-6 range. However, there exists only one report on the formation of a chiral nematic copolymer with cholesterol as the chiral moiety. Since several chiral building blocks other than cholesterol have been found to possess strong helical twisting powers with selected nematogenic monomers, it would be of interest to explore a cyanobiphenyl group as a building block for the synthesis of new chiral nematic copolymers.« less

  3. Photoexcitation circular dichroism in chiral molecules

    NASA Astrophysics Data System (ADS)

    Beaulieu, S.; Comby, A.; Descamps, D.; Fabre, B.; Garcia, G. A.; Géneaux, R.; Harvey, A. G.; Légaré, F.; Mašín, Z.; Nahon, L.; Ordonez, A. F.; Petit, S.; Pons, B.; Mairesse, Y.; Smirnova, O.; Blanchet, V.

    2018-05-01

    Chiral effects appear in a wide variety of natural phenomena and are of fundamental importance in science, from particle physics to metamaterials. The standard technique of chiral discrimination—photoabsorption circular dichroism—relies on the magnetic properties of a chiral medium and yields an extremely weak chiral response. Here, we propose and demonstrate an orders of magnitude more sensitive type of circular dichroism in neutral molecules: photoexcitation circular dichroism. This technique does not rely on weak magnetic effects, but takes advantage of the coherent helical motion of bound electrons excited by ultrashort circularly polarized light. It results in an ultrafast chiral response and the efficient excitation of a macroscopic chiral density in an initially isotropic ensemble of randomly oriented chiral molecules. We probe this excitation using linearly polarized laser pulses, without the aid of further chiral interactions. Our time-resolved study of vibronic chiral dynamics opens a way to the efficient initiation, control and monitoring of chiral chemical change in neutral molecules at the level of electrons.

  4. Maltodextrins as chiral selectors in CE: molecular structure effect of basic chiral compounds on the enantioseparation.

    PubMed

    Tabani, Hadi; Fakhari, Ali Reza; Nojavan, Saeed

    2014-10-01

    Prediction of chiral separation for a compound using a chiral selector is an interesting and debatable work. For this purpose, in this study 23 chiral basic drugs with different chemical structures were selected as model solutes and the influence of their chemical structures on the enantioseparation in the presence of maltodextrin (MD) as chiral selector was investigated. For chiral separation, a 100-mM phosphate buffer solution (pH 3.0) containing 10% (w/v) MD with dextrose equivalent (DE) of 4-7 as chiral selector at the temperature of 25°C and voltage of 20 kV was used. Under this condition, baseline separation was achieved for nine chiral compounds and partial separation was obtained for another six chiral compounds while no enantioseparation was obtained for the remaining eight compounds. The results showed that the existence of at least two aromatic rings or cycloalkanes and an oxygen or nitrogen atom or -CN group directly bonded to the chiral center are necessary for baseline separation. With the obtained results in this study, chiral separation of a chiral compound can be estimated with MD-modified capillary electrophoresis before analysis. This prediction will minimize the number of preliminary experiments required to resolve enantiomers and will save time and cost. © 2014 Wiley Periodicals, Inc.

  5. Observation of chiral phonons

    NASA Astrophysics Data System (ADS)

    Zhu, Hanyu; Yi, Jun; Li, Ming-Yang; Xiao, Jun; Zhang, Lifa; Yang, Chih-Wen; Kaindl, Robert A.; Li, Lain-Jong; Wang, Yuan; Zhang, Xiang

    2018-02-01

    Chirality reveals symmetry breaking of the fundamental interaction of elementary particles. In condensed matter, for example, the chirality of electrons governs many unconventional transport phenomena such as the quantum Hall effect. Here we show that phonons can exhibit intrinsic chirality in monolayer tungsten diselenide. The broken inversion symmetry of the lattice lifts the degeneracy of clockwise and counterclockwise phonon modes at the corners of the Brillouin zone. We identified the phonons by the intervalley transfer of holes through hole-phonon interactions during the indirect infrared absorption, and we confirmed their chirality by the infrared circular dichroism arising from pseudoangular momentum conservation. The chiral phonons are important for electron-phonon coupling in solids, phonon-driven topological states, and energy-efficient information processing.

  6. Meta-Chirality: Fundamentals, Construction and Applications

    PubMed Central

    Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Guo, Yinghui; Gao, Ping; Luo, Xiangang

    2017-01-01

    Chiral metamaterials represent a special type of artificial structures that cannot be superposed to their mirror images. Due to the lack of mirror symmetry, cross-coupling between electric and magnetic fields exist in chiral mediums and present unique electromagnetic characters of circular dichroism and optical activity, which provide a new opportunity to tune polarization and realize negative refractive index. Chiral metamaterials have attracted great attentions in recent years and have given rise to a series of applications in polarization manipulation, imaging, chemical and biological detection, and nonlinear optics. Here we review the fundamental theory of chiral media and analyze the construction principles of some typical chiral metamaterials. Then, the progress in extrinsic chiral metamaterials, absorbing chiral metamaterials, and reconfigurable chiral metamaterials are summarized. In the last section, future trends in chiral metamaterials and application in nonlinear optics are introduced. PMID:28513560

  7. Strong Field Quenching of the Quasiparticle Effective Mass in Heavy Fermion Compound YbCo2Zn20

    NASA Astrophysics Data System (ADS)

    Masahiro Ohya,; Masaki Matsushita,; Shingo Yoshiuchi,; Tetsuya Takeuchi,; Fuminori Honda,; Rikio Settai,; Toshiki Tanaka,; Yasunori Kubo,; Yoshichika Ōnuki,

    2010-08-01

    We found a metamagnetic like anomaly at Hm≃ 5 kOe in a heavy fermion compound YbCo2Zn20 below the characteristic temperature Tχ_{max}=0.32 K where the ac-susceptibility shows a broad peak, suggesting that an electronic state with a very low Kondo temperature is realized. Interestingly, the metamagnetic like behavior was observed as two peaks at 4.0 and 7.5 kOe at 95 mK in the magnetic field dependence of the electronic specific heat C/T. The extremely large values of the electronic specific heat coefficient γ≃ 8000 mJ/(K2\\cdotmol) and A=160 μΩ\\cdotcm/K2 in the electrical resistivity ρ=ρ0+AT2 at H=0 kOe are most likely due to the very low Kondo temperature. The \\sqrt{A} value was, however, found to be strongly reduced from \\sqrt{A}=12.6 (μΩ\\cdotcm/K2)1/2 at 0 kOe to 0.145 (μΩ\\cdotcm/K2)1/2 at 150 kOe. Therefore, we considered that the corresponding cyclotron effective mass mc*, which was determined from the temperature dependence of the de Haas-van Alphen (dHvA) amplitude, is also reduced with increasing magnetic field and is in fact not large, ranging from 2 to 9m0 at 117 kOe. From the field dependence of \\sqrt{A} and mc*, we estimated the cyclotron effective mass at 0 kOe to be 100--500m0, revealing the largest cyclotron mass as far as we know.

  8. Chirality-controlled crystallization via screw dislocations.

    PubMed

    Sung, Baeckkyoung; de la Cotte, Alexis; Grelet, Eric

    2018-04-11

    Chirality plays an important role in science from enantiomeric separation in chemistry to chiral plasmonics in nanotechnology. However, the understanding of chirality amplification from chiral building blocks to ordered helical superstructures remains a challenge. Here, we demonstrate that topological defects, such as screw dislocations, can drive the chirality transfer from particle to supramolecular structure level during the crystallization process. By using a model system of chiral particles, which enables direct imaging of single particle incorporation into growing crystals, we show that the crystallization kinetic pathway is the key parameter for monitoring, via the defects, the chirality amplification of the crystalline structures from racemic to predominantly homohelical. We provide an explanation based on the interplay between geometrical frustration, racemization induced by thermal fluctuations, and particle chirality. Our results demonstrate that screw dislocations not only promote the growth, but also control the chiral morphology and therefore the functionality of crystalline states.

  9. Fermionic currents in AdS spacetime with compact dimensions

    NASA Astrophysics Data System (ADS)

    Bellucci, S.; Saharian, A. A.; Vardanyan, V.

    2017-09-01

    We derive a closed expression for the vacuum expectation value (VEV) of the fermionic current density in a (D +1 )-dimensional locally AdS spacetime with an arbitrary number of toroidally compactified Poincaré spatial dimensions and in the presence of a constant gauge field. The latter can be formally interpreted in terms of a magnetic flux treading the compact dimensions. In the compact subspace, the field operator obeys quasiperiodicity conditions with arbitrary phases. The VEV of the charge density is zero and the current density has nonzero components along the compact dimensions only. They are periodic functions of the magnetic flux with the period equal to the flux quantum and tend to zero on the AdS boundary. Near the horizon, the effect of the background gravitational field is small and the leading term in the corresponding asymptotic expansion coincides with the VEV for a massless field in the locally Minkowski bulk. Unlike the Minkowskian case, in the system consisting of an equal number of fermionic and scalar degrees of freedom, with same masses, charges and phases in the periodicity conditions, the total current density does not vanish. In these systems, the leading divergences in the scalar and fermionic contributions on the horizon are canceled and, as a consequence of that, the charge flux, integrated over the coordinate perpendicular to the AdS boundary, becomes finite. We show that in odd spacetime dimensions the fermionic fields realizing two inequivalent representations of the Clifford algebra and having equal phases in the periodicity conditions give the same contribution to the VEV of the current density. Combining the contributions from these fields, the current density in odd-dimensional C -,P - and T -symmetric models are obtained. As an application, we consider the ground state current density in curved carbon nanotubes described in terms of a (2 +1 )-dimensional effective Dirac model.

  10. Spin Chirality of Cu3 and V3 Nanomagnets. 1. Rotation Behavior of Vector Chirality, Scalar Chirality, and Magnetization in the Rotating Magnetic Field, Magnetochiral Correlations.

    PubMed

    Belinsky, Moisey I

    2016-05-02

    The rotation behavior of the vector chirality κ, scalar chirality χ, and magnetization M in the rotating magnetic field H1 is considered for the V3 and Cu3 nanomagnets, in which the Dzialoshinsky-Moriya coupling is active. The polar rotation of the field H1 of the given strength H1 results in the energy spectrum characterized by different vector and scalar chiralities in the ground and excited states. The magnetochiral correlations between the vector and scalar chiralities, energy, and magnetization in the rotating field were considered. Under the uniform polar rotation of the field H1, the ground-state chirality vector κI performs sawtooth oscillations and the magnetization vector MI performs the sawtooth oscillating rotation that is accompanied by the correlated transformation of the scalar chirality χI. This demonstrates the magnetochiral effect of the joint rotation behavior and simultaneous frustrations of the spin chiralities and magnetization in the rotating field, which are governed by the correlation between the chiralities and magnetization.

  11. Non-Abelian statistics of vortices with non-Abelian Dirac fermions.

    PubMed

    Yasui, Shigehiro; Hirono, Yuji; Itakura, Kazunori; Nitta, Muneto

    2013-05-01

    We extend our previous analysis on the exchange statistics of vortices having a single Dirac fermion trapped in each core to the case where vortices trap two Dirac fermions with U(2) symmetry. Such a system of vortices with non-Abelian Dirac fermions appears in color superconductors at extremely high densities and in supersymmetric QCD. We show that the exchange of two vortices having doublet Dirac fermions in each core is expressed by non-Abelian representations of a braid group, which is explicitly verified in the matrix representation of the exchange operators when the number of vortices is up to four. We find that the result contains the matrices previously obtained for the vortices with a single Dirac fermion in each core as a special case. The whole braid group does not immediately imply non-Abelian statistics of identical particles because it also contains exchanges between vortices with different numbers of Dirac fermions. However, we find that it does contain, as its subgroup, genuine non-Abelian statistics for the exchange of the identical particles, that is, vortices with the same number of Dirac fermions. This result is surprising compared with conventional understanding because all Dirac fermions are defined locally at each vortex, unlike the case of Majorana fermions for which Dirac fermions are defined nonlocally by Majorana fermions located at two spatially separated vortices.

  12. The isospin strange asymmetry from the chiral effective theory

    NASA Astrophysics Data System (ADS)

    Trevisan, Luis Augusto; Mirez, Carlos

    2018-05-01

    The proposal of the present work is to study the difference between the strange quark-antiquark amount in the proton and neutron. For this purpose, the possible nucleon-hyperon-kaon fluctuations are analyzed with the effective chiral theory. The small difference of particle masses is shown to be in the origin of this isospin asymmetry. The dependence of the results on the mass cutoff parameter and with the coupling constants is analyzed.

  13. Auxiliary field diffusion Monte Carlo calculations of light and medium-mass nuclei with local chiral interactions

    NASA Astrophysics Data System (ADS)

    Lonardoni, D.; Gandolfi, S.; Lynn, J. E.; Petrie, C.; Carlson, J.; Schmidt, K. E.; Schwenk, A.

    2018-04-01

    Quantum Monte Carlo methods have recently been employed to study properties of nuclei and infinite matter using local chiral effective-field-theory interactions. In this work, we present a detailed description of the auxiliary field diffusion Monte Carlo algorithm for nuclei in combination with local chiral two- and three-nucleon interactions up to next-to-next-to-leading order. We show results for the binding energy, charge radius, charge form factor, and Coulomb sum rule in nuclei with 3 ≤A ≤16 . Particular attention is devoted to the effect of different operator structures in the three-body force for different cutoffs. The outcomes suggest that local chiral interactions fit to few-body observables give a very good description of the ground-state properties of nuclei up to 16O, with the exception of one fit for the softer cutoff which predicts overbinding in larger nuclei.

  14. Chirality and protein biosynthesis.

    PubMed

    Banik, Sindrila Dutta; Nandi, Nilashis

    2013-01-01

    Chirality is present at all levels of structural hierarchy of protein and plays a significant role in protein biosynthesis. The macromolecules involved in protein biosynthesis such as aminoacyl tRNA synthetase and ribosome have chiral subunits. Despite the omnipresence of chirality in the biosynthetic pathway, its origin, role in current pathway, and importance is far from understood. In this review we first present an introduction to biochirality and its relevance to protein biosynthesis. Major propositions about the prebiotic origin of biomolecules are presented with particular reference to proteins and nucleic acids. The problem of the origin of homochirality is unresolved at present. The chiral discrimination by enzymes involved in protein synthesis is essential for keeping the life process going. However, questions remained pertaining to the mechanism of chiral discrimination and concomitant retention of biochirality. We discuss the experimental evidence which shows that it is virtually impossible to incorporate D-amino acids in protein structures in present biosynthetic pathways via any of the two major steps of protein synthesis, namely aminoacylation and peptide bond formation reactions. Molecular level explanations of the stringent chiral specificity in each step are extended based on computational analysis. A detailed account of the current state of understanding of the mechanism of chiral discrimination during aminoacylation in the active site of aminoacyl tRNA synthetase and peptide bond formation in ribosomal peptidyl transferase center is presented. Finally, it is pointed out that the understanding of the mechanism of retention of enantiopurity has implications in developing novel enzyme mimetic systems and biocatalysts and might be useful in chiral drug design.

  15. Finite volume for three-flavour Partially Quenched Chiral Perturbation Theory through NNLO in the meson sector

    NASA Astrophysics Data System (ADS)

    Bijnens, Johan; Rössler, Thomas

    2015-11-01

    We present a calculation of the finite volume corrections to meson masses and decay constants in three flavour Partially Quenched Chiral Perturbation Theory (PQChPT) through two-loop order in the chiral expansion for the flavour-charged (or off-diagonal) pseudoscalar mesons. The analytical results are obtained for three sea quark flavours with one, two or three different masses. We reproduce the known infinite volume results and the finite volume results in the unquenched case. The calculation has been performed using the supersymmetric formulation of PQChPT as well as with a quark flow technique.

  16. Fermion localization on a split brane

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chumbes, A. E. R.; Vasquez, A. E. O.; Hott, M. B.

    2011-05-15

    In this work we analyze the localization of fermions on a brane embedded in five-dimensional, warped and nonwarped, space-time. In both cases we use the same nonlinear theoretical model with a nonpolynomial potential featuring a self-interacting scalar field whose minimum energy solution is a soliton (a kink) which can be continuously deformed into a two-kink. Thus a single brane splits into two branes. The behavior of spin 1/2 fermions wave functions on the split brane depends on the coupling of fermions to the scalar field and on the geometry of the space-time.

  17. High-spin level structure and Ground-state phase transition in the odd-mass 103-109Rh isotopes in the framework of exactly solvable sdg interacting boson-fermion model

    NASA Astrophysics Data System (ADS)

    Ghapanvari, M.; Ghorashi, A. H.; Ranjbar, Z.; Jafarizadeh, M. A.

    2018-03-01

    In this article, the negative-parity states in the odd-mass 103 - 109Rh isotopes in terms of the sd and sdg interacting-boson fermion models were studied. The transitional interacting boson-fermion model Hamiltonians in sd and sdg-IBFM versions based on affine SU (1 , 1) Lie Algebra were employed to describe the evolution from the spherical to deformed gamma unstable shapes along with the chain of Rh isotopes. In this method, sdg-IBFM Hamiltonian, which is a three level pairing Hamiltonian was determined easily via the exactly solvable method. Some observables of the shape phase transitions such as energy levels, the two neutron separation energies, signature splitting of the γ-vibrational band, the α-decay and double β--decay energies were calculated and examined for these isotopes. The present calculation correctly reproduces the spherical to gamma-soft phase transition in the Rh isotopes. Some comparisons were made with sd-IBFM.

  18. Neutrino mass with large S U (2 )L multiplet fields

    NASA Astrophysics Data System (ADS)

    Nomura, Takaaki; Okada, Hiroshi

    2017-11-01

    We propose an extension of the standard model introducing large S U (2 )L multiplet fields which are quartet and septet scalars and quintet Majorana fermions. These multiplets can induce the neutrino masses via interactions with the S U (2 ) doublet leptons. We then find the neutrino masses are suppressed by a small vacuum expectation value of the quartet/septet and an inverse of the quintet fermion mass, relaxing the Yukawa hierarchies among the standard model fermions. We also discuss collider physics at the Large Hadron Collider, considering the production of charged particles in these multiplets, and due to the effects of violating the custodial symmetry, some specific signatures can be found. Then, we discuss the detectability of these signals.

  19. Role of Achiral Nucleobases in Multicomponent Chiral Self-Assembly: Purine-Triggered Helix and Chirality Transfer.

    PubMed

    Deng, Ming; Zhang, Li; Jiang, Yuqian; Liu, Minghua

    2016-11-21

    Chiral self-assembly is a basic process in biological systems, where many chiral biomolecules such as amino acids and sugars play important roles. Achiral nucleobases usually covalently bond to saccharides and play a significant role in the formation of the double helix structure. However, it remains unclear how the achiral nucleobases can function in chiral self-assembly without the sugar modification. Herein, we have clarified that purine nucleobases could trigger N-(9-fluorenylmethox-ycarbonyl) (Fmoc)-protected glutamic acid to self-assemble into helical nanostructures. Moreover, the helical nanostructure could serve as a matrix and transfer the chirality to an achiral fluorescence probe, thioflavin T (ThT). Upon chirality transfer, the ThT showed not only supramolecular chirality but also circular polarized fluorescence (CPL). Without the nucleobase, the self-assembly processes cannot happen, thus providing an example where achiral molecules played an essential role in the expression and transfer of the chirality. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Timoshenko beam model for chiral materials

    NASA Astrophysics Data System (ADS)

    Ma, T. Y.; Wang, Y. N.; Yuan, L.; Wang, J. S.; Qin, Q. H.

    2017-12-01

    Natural and artificial chiral materials such as deoxyribonucleic acid (DNA), chromatin fibers, flagellar filaments, chiral nanotubes, and chiral lattice materials widely exist. Due to the chirality of intricately helical or twisted microstructures, such materials hold great promise for use in diverse applications in smart sensors and actuators, force probes in biomedical engineering, structural elements for absorption of microwaves and elastic waves, etc. In this paper, a Timoshenko beam model for chiral materials is developed based on noncentrosymmetric micropolar elasticity theory. The governing equations and boundary conditions for a chiral beam problem are derived using the variational method and Hamilton's principle. The static bending and free vibration problem of a chiral beam are investigated using the proposed model. It is found that chirality can significantly affect the mechanical behavior of beams, making materials more flexible compared with nonchiral counterparts, inducing coupled twisting deformation, relatively larger deflection, and lower natural frequency. This study is helpful not only for understanding the mechanical behavior of chiral materials such as DNA and chromatin fibers and characterizing their mechanical properties, but also for the design of hierarchically structured chiral materials.

  1. Timoshenko beam model for chiral materials

    NASA Astrophysics Data System (ADS)

    Ma, T. Y.; Wang, Y. N.; Yuan, L.; Wang, J. S.; Qin, Q. H.

    2018-06-01

    Natural and artificial chiral materials such as deoxyribonucleic acid (DNA), chromatin fibers, flagellar filaments, chiral nanotubes, and chiral lattice materials widely exist. Due to the chirality of intricately helical or twisted microstructures, such materials hold great promise for use in diverse applications in smart sensors and actuators, force probes in biomedical engineering, structural elements for absorption of microwaves and elastic waves, etc. In this paper, a Timoshenko beam model for chiral materials is developed based on noncentrosymmetric micropolar elasticity theory. The governing equations and boundary conditions for a chiral beam problem are derived using the variational method and Hamilton's principle. The static bending and free vibration problem of a chiral beam are investigated using the proposed model. It is found that chirality can significantly affect the mechanical behavior of beams, making materials more flexible compared with nonchiral counterparts, inducing coupled twisting deformation, relatively larger deflection, and lower natural frequency. This study is helpful not only for understanding the mechanical behavior of chiral materials such as DNA and chromatin fibers and characterizing their mechanical properties, but also for the design of hierarchically structured chiral materials.

  2. Enantiopure Ferrocene-Based Planar-Chiral Iridacycles: Stereospecific Control of Iridium-Centred Chirality.

    PubMed

    Arthurs, Ross A; Ismail, Muhammad; Prior, Christopher C; Oganesyan, Vasily S; Horton, Peter N; Coles, Simon J; Richards, Christopher J

    2016-02-24

    Reaction of [IrCp*Cl2 ]2 with ferrocenylimines (Fc=NAr, Ar=Ph, p-MeOC6 H4 ) results in ferrocene C-H activation and the diastereoselective synthesis of half-sandwich iridacycles of relative configuration Sp *,RIr *. Extension to (S)-2-ferrocenyl-4-(1-methylethyl)oxazoline gave highly diastereoselective control over the new elements of planar chirality and metal-based pseudo-tetrahedral chirality, to give both neutral and cationic half-sandwich iridacycles of absolute configuration Sc ,Sp ,RIr . Substitution reactions proceed with retention of configuration, with the planar chirality controlling the metal-centred chirality through an iron-iridium interaction in the coordinatively unsaturated cationic intermediate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Amplified fermion production from overpopulated Bose fields

    NASA Astrophysics Data System (ADS)

    Berges, J.; Gelfand, D.; Sexty, D.

    2014-01-01

    We study the real-time dynamics of fermions coupled to scalar fields in a linear sigma model, which is often employed in the context of preheating after inflation or as a low-energy effective model for quantum chromodynamics. We find a dramatic amplification of fermion production in the presence of highly occupied bosonic quanta for weak as well as strong effective couplings. For this we consider the range of validity of different methods: lattice simulations with male/female fermions, the mode functions approach and the quantum 2PI effective action with its associated kinetic theory. For strongly coupled fermions we find a rapid approach to a Fermi-Dirac distribution with time-dependent temperature and chemical potential parameters, while the bosons are still far from equilibrium.

  4. Chiral Anomalous Dispersion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sadofyev, Andrey; Sen, Srimoyee

    The linearized Einstein equation describing graviton propagation through a chiral medium appears to be helicity dependent. We analyze features of the corresponding spectrum in a collision-less regime above a flat background. In the long wave-length limit, circularly polarized metric perturbations travel with a helicity dependent group velocity that can turn negative giving rise to a new type of an anomalous dispersion. We further show that this chiral anomalous dispersion is a general feature of polarized modes propagating through chiral plasmas extending our result to the electromagnetic sector.

  5. Chiral Anomalous Dispersion

    DOE PAGES

    Sadofyev, Andrey; Sen, Srimoyee

    2018-02-16

    The linearized Einstein equation describing graviton propagation through a chiral medium appears to be helicity dependent. We analyze features of the corresponding spectrum in a collision-less regime above a flat background. In the long wave-length limit, circularly polarized metric perturbations travel with a helicity dependent group velocity that can turn negative giving rise to a new type of an anomalous dispersion. We further show that this chiral anomalous dispersion is a general feature of polarized modes propagating through chiral plasmas extending our result to the electromagnetic sector.

  6. Fermionic entanglement that survives a black hole

    NASA Astrophysics Data System (ADS)

    Martín-Martínez, Eduardo; León, Juan

    2009-10-01

    We introduce an arbitrary number of accessible modes when analyzing bipartite entanglement degradation due to Unruh effect between two partners Alice and Rob. Under the single mode approximation (SMA) a fermion field only had a few accessible levels due to Pauli exclusion principle conversely to bosonic fields which had an infinite number of excitable levels. This was argued to justify entanglement survival in the fermionic case in the SMA infinite acceleration limit. Here we relax SMA. Hence, an infinite number of modes are excited as the observer Rob accelerates, even for a fermion field. We will prove that, despite this analogy with the bosonic case, entanglement loss is limited. We will show that this comes from fermionic statistics through the characteristic structure it imposes on the infinite dimensional density matrix for Rob. Surprisingly, the surviving entanglement is independent of the specific maximally entangled state chosen, the kind of fermionic field analyzed, and the number of accessible modes considered. We shall discuss whether this surviving entanglement goes beyond the purely statistical correlations, giving insight concerning the black hole information paradox.

  7. Auxiliary field diffusion Monte Carlo calculations of light and medium-mass nuclei with local chiral interactions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lonardoni, D.; Gandolfi, S.; Lynn, J. E.

    Quantum Monte Carlo methods have recently been employed to study properties of nuclei and infinite matter using local chiral effective-field-theory interactions. In this paper, we present a detailed description of the auxiliary field diffusion Monte Carlo algorithm for nuclei in combination with local chiral two- and three-nucleon interactions up to next-to-next-to-leading order. We show results for the binding energy, charge radius, charge form factor, and Coulomb sum rule in nuclei withmore » $$3{\\le}A{\\le}16$$. Particular attention is devoted to the effect of different operator structures in the three-body force for different cutoffs. Finally, the outcomes suggest that local chiral interactions fit to few-body observables give a very good description of the ground-state properties of nuclei up to $$^{16}\\mathrm{O}$$, with the exception of one fit for the softer cutoff which predicts overbinding in larger nuclei.« less

  8. Auxiliary field diffusion Monte Carlo calculations of light and medium-mass nuclei with local chiral interactions

    DOE PAGES

    Lonardoni, D.; Gandolfi, S.; Lynn, J. E.; ...

    2018-04-24

    Quantum Monte Carlo methods have recently been employed to study properties of nuclei and infinite matter using local chiral effective-field-theory interactions. In this paper, we present a detailed description of the auxiliary field diffusion Monte Carlo algorithm for nuclei in combination with local chiral two- and three-nucleon interactions up to next-to-next-to-leading order. We show results for the binding energy, charge radius, charge form factor, and Coulomb sum rule in nuclei withmore » $$3{\\le}A{\\le}16$$. Particular attention is devoted to the effect of different operator structures in the three-body force for different cutoffs. Finally, the outcomes suggest that local chiral interactions fit to few-body observables give a very good description of the ground-state properties of nuclei up to $$^{16}\\mathrm{O}$$, with the exception of one fit for the softer cutoff which predicts overbinding in larger nuclei.« less

  9. Chiral Responsive Liquid Quantum Dots.

    PubMed

    Zhang, Jin; Ma, Junkai; Shi, Fangdan; Tian, Demei; Li, Haibing

    2017-08-01

    How to convert the weak chiral-interaction into the macroscopic properties of materials remains a huge challenge. Here, this study develops highly fluorescent, selectively chiral-responsive liquid quantum dots (liquid QDs) based on the hydrophobic interaction between the chiral chains and the oleic acid-stabilized QDs, which have been designated as (S)-1810-QDs. The fluorescence spectrum and liquidity of thermal control demonstrate the fluorescence properties and the fluidic behavior of (S)-1810-QDs in the solvent-free state. Especially, (S)-1810-QDs exhibit a highly chiral-selective response toward (1R, 2S)-2-amino-1,2-diphenyl ethanol. It is anticipated that this study will facilitate the construction of smart chiral fluidic sensors. More importantly, (S)-1810-QDs can become an attractive material for chiral separation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Observation of chiral phonons.

    PubMed

    Zhu, Hanyu; Yi, Jun; Li, Ming-Yang; Xiao, Jun; Zhang, Lifa; Yang, Chih-Wen; Kaindl, Robert A; Li, Lain-Jong; Wang, Yuan; Zhang, Xiang

    2018-02-02

    Chirality reveals symmetry breaking of the fundamental interaction of elementary particles. In condensed matter, for example, the chirality of electrons governs many unconventional transport phenomena such as the quantum Hall effect. Here we show that phonons can exhibit intrinsic chirality in monolayer tungsten diselenide. The broken inversion symmetry of the lattice lifts the degeneracy of clockwise and counterclockwise phonon modes at the corners of the Brillouin zone. We identified the phonons by the intervalley transfer of holes through hole-phonon interactions during the indirect infrared absorption, and we confirmed their chirality by the infrared circular dichroism arising from pseudoangular momentum conservation. The chiral phonons are important for electron-phonon coupling in solids, phonon-driven topological states, and energy-efficient information processing. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  11. On the regularized fermionic projector of the vacuum

    NASA Astrophysics Data System (ADS)

    Finster, Felix

    2008-03-01

    We construct families of fermionic projectors with spherically symmetric regularization, which satisfy the condition of a distributional MP-product. The method is to analyze regularization tails with a power law or logarithmic scaling in composite expressions in the fermionic projector. The resulting regularizations break the Lorentz symmetry and give rise to a multilayer structure of the fermionic projector near the light cone. Furthermore, we construct regularizations which go beyond the distributional MP-product in that they yield additional distributional contributions supported at the origin. The remaining freedom for the regularization parameters and the consequences for the normalization of the fermionic states are discussed.

  12. Development of a chiral micellar electrokinetic chromatography-tandem mass spectrometry assay for simultaneous analysis of warfarin and hydroxywarfarin metabolites: application to the analysis of patients serum samples.

    PubMed

    Wang, Xiaochun; Hou, Jingguo; Jann, Michael; Hon, Yuen Yi; Shamsi, Shahab A

    2013-01-04

    The enantioseparation of warfarin (WAR) along with the five positional and optical isomers is challenging because of the difficulty to simultaneously separate and quantitate these chiral compounds. Currently, no effective chiral CE-MS methods exist for the simultaneous enantioseparation of WAR and all its hydroxylated metabolites in a single run. Polymeric surfactants (aka. molecular micelles) are particularly compatible with micellar electrokinetic chromatography-mass spectrometry (MEKC-MS) because they have a wider elution window for enantioseparation and do not interfere with the MS detection of chiral drugs. Using polysodium N-undecenoyl-L,L-leucylvalinate (poly-L,L-SULV) as a chiral pseudophase in MEKC-MS baseline separation of WAR, its five metabolites along with the internal standard was obtained in 45 min. This is in comparison to 100 min required for separation of the same mixture with packed column CEC-MS using a vancomycin chiral stationary phase. Serum samples were extracted with mixed-mode anion-exchange (MAX) cartridge with recoveries of greater than 85.2% for all WAR and hydroxywarfarin (OH-WAR) metabolites. Utilizing the tandem MS and multiple reaction monitoring mode, the MEKC-MS/MS method was used to simultaneously generate calibration curves over a concentration range from 2 to 5000 ng/mL for R- and S-warfarin, 5 to 1000 ng/mL for R- and S-6-, 7-, 8- and 10-OH-WAR and 10 to 1000 ng/mL for R and S-4'-OH-WAR. For the first time, the limits of detection and quantitation for most WAR metabolites by MEKC-MS/MS were found to be at levels of 2 and 5 ng/mL, respectively. The method was successfully applied for the first time to analyze WAR and its metabolites in plasma samples of 55 patients undergoing WAR therapy, demonstrating the potential of chiral MEKC-MS/MS method to accurately quantitate with high sensitivity. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Hamiltonian Cycle Enumeration via Fermion-Zeon Convolution

    NASA Astrophysics Data System (ADS)

    Staples, G. Stacey

    2017-12-01

    Beginning with a simple graph having finite vertex set V, operators are induced on fermion and zeon algebras by the action of the graph's adjacency matrix and combinatorial Laplacian on the vector space spanned by the graph's vertices. When the graph is simple (undirected with no loops or multiple edges), the matrices are symmetric and the induced operators are self-adjoint. The goal of the current paper is to recover a number of known graph-theoretic results from quantum observables constructed as linear operators on fermion and zeon Fock spaces. By considering an "indeterminate" fermion/zeon Fock space, a fermion-zeon convolution operator is defined whose trace recovers the number of Hamiltonian cycles in the graph. This convolution operator is a quantum observable whose expectation reveals the number of Hamiltonian cycles in the graph.

  14. Discrete symmetries and the propagator approach to coupled fermions in Quantum Field Theory. Generalities: The case of a single fermion-antifermion pair

    NASA Astrophysics Data System (ADS)

    Duret, Q.; Machet, B.

    2010-10-01

    Starting from Wigner's symmetry representation theorem, we give a general account of discrete symmetries (parity P, charge conjugation C, time-reversal T), focusing on fermions in Quantum Field Theory. We provide the rules of transformation of Weyl spinors, both at the classical level (grassmanian wave functions) and quantum level (operators). Making use of Wightman's definition of invariance, we outline ambiguities linked to the notion of classical fermionic Lagrangian. We then present the general constraints cast by these transformations and their products on the propagator of the simplest among coupled fermionic system, the one made with one fermion and its antifermion. Last, we put in correspondence the propagation of C eigenstates (Majorana fermions) and the criteria cast on their propagator by C and CP invariance.

  15. Increments to chiral recognition facilitating enantiomer separations of chiral acids, bases, and ampholytes using Cinchona-based zwitterion exchanger chiral stationary phases.

    PubMed

    Wernisch, Stefanie; Pell, Reinhard; Lindner, Wolfgang

    2012-07-01

    The intramolecular distances of anion and cation exchanger sites of zwitterionic chiral stationary phases represent potential tuning sites for enantiomer selectivity. In this contribution, we investigate the influence of alkanesulfonic acid chain length and flexibility on enantiomer separations of chiral acids, bases, and amphoteric molecules for six Cinchona alkaloid-based chiral stationary phases in comparison with structurally related anion and cation exchangers. Employing polar-organic elution conditions, we observed an intramolecular counterion effect for acidic analytes which led to reduced retention times but did not impair enantiomer selectivities. Retention of amphoteric analytes is based on simultaneous double ion pairing of their charged functional groups with the acidic and basic sites of the zwitterionic selectors. A chiral center in the vicinity of the strong cation exchanger site is vital for chiral separations of bases. Sterically demanding side chains are beneficial for separations of free amino acids. Enantioseparations of free (un-derivatized) peptides were particularly successful in stationary phases with straight-chain alkanesulfonic acid sites, pointing to a beneficial influence of more flexible moieties. In addition, we observed pseudo-enantiomeric behavior of quinine and quinidine-derived chiral stationary phases facilitating reversal of elution orders for all analytes. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Chiral liquid crystal colloids

    NASA Astrophysics Data System (ADS)

    Yuan, Ye; Martinez, Angel; Senyuk, Bohdan; Tasinkevych, Mykola; Smalyukh, Ivan I.

    2018-01-01

    Colloidal particles disturb the alignment of rod-like molecules of liquid crystals, giving rise to long-range interactions that minimize the free energy of distorted regions. Particle shape and topology are known to guide this self-assembly process. However, how chirality of colloidal inclusions affects these long-range interactions is unclear. Here we study the effects of distortions caused by chiral springs and helices on the colloidal self-organization in a nematic liquid crystal using laser tweezers, particle tracking and optical imaging. We show that chirality of colloidal particles interacts with the nematic elasticity to predefine chiral or racemic colloidal superstructures in nematic colloids. These findings are consistent with numerical modelling based on the minimization of Landau-de Gennes free energy. Our study uncovers the role of chirality in defining the mesoscopic order of liquid crystal colloids, suggesting that this feature may be a potential tool to modulate the global orientated self-organization of these systems.

  17. Superfluid Boson-Fermion Mixture: Structure Formation and Collective Periodic Motion

    NASA Astrophysics Data System (ADS)

    Mitra, A.

    2018-01-01

    Multiple periodic domain formation due to a modulation instability in a boson-fermion mixture superfluid in the unitary regime has been studied. The periodicity of the structure evolves with time. At the early stage of evolution, bosonic domains show the periodic nature, whereas the periodicity in the fermionic (Cooper pair) domains appears at the late stage of evolution. The nature of interatomic interspecies interactions affects the domain formation. In a harmonic trap, the mixture executes an undamped oscillation. The frequency of the oscillation depends on the relative coupling strength between boson-fermion and fermion-fermion. The repulsive boson-fermion interaction reduces the oscillation frequency, whereas the attractive interaction enhances the frequency significantly.

  18. Cell Chirality Drives Left-Right Asymmetric Morphogenesis.

    PubMed

    Inaki, Mikiko; Sasamura, Takeshi; Matsuno, Kenji

    2018-01-01

    Most macromolecules found in cells are chiral, meaning that they cannot be superimposed onto their mirror image. However, cells themselves can also be chiral, a subject that has received little attention until very recently. In our studies on the mechanisms of left-right (LR) asymmetric development in Drosophila , we discovered that cells can have an intrinsic chirality to their structure, and that this "cell chirality" is generally responsible for the LR asymmetric development of certain organs in this species. The actin cytoskeleton plays important roles in the formation of cell chirality. In addition, Myosin31DF ( Myo31DF ), which encodes Drosophila Myosin ID, was identified as a molecular switch for cell chirality. In other invertebrate species, including snails and Caenorhabditis elegans , chirality of the blastomeres, another type of cell chirality, determines the LR asymmetry of structures in the body. Thus, chirality at the cellular level may broadly contribute to LR asymmetric development in various invertebrate species. Recently, cell chirality was also reported for various vertebrate cultured cells, and studies suggested that cell chirality is evolutionarily conserved, including the essential role of the actin cytoskeleton. Although the biological roles of cell chirality in vertebrates remain unknown, it may control LR asymmetric development or other morphogenetic events. The investigation of cell chirality has just begun, and this new field should provide valuable new insights in biology and medicine.

  19. ENANTIOMERIC COMPOSITION OF CHIRAL POLYCHLORINATED BIPHENYL ATROPISOMERS IN AQUATIC BED SEDIMENT

    EPA Science Inventory

    Enantiomeric ratios (ERs) for eight polychlorinated biphenyl (PCB) atropisomers were measured in aquatic sediment from selected sites throughout the United States by using chiral gas chromatography/mass spectrometry. Nonracemic ERs for PCBs 91, 95, 132, 136, 149, 174, and 176 wer...

  20. Enantioselective determination of (R)-zopiclone and (S)-zopiclone (eszopiclone) in human hair by micropulverized extraction and chiral liquid chromatography/high resolution mass spectrometry.

    PubMed

    Miyaguchi, Hajime; Kuwayama, Kenji

    2017-10-13

    Zopiclone and its (S)-enantiomer (eszopiclone) are commonly prescribed for insomnia. Despite the high demand for enantioselective differentiation, the chiral analysis of zopiclone in hair has not been reported. In this study, a method for the enantioselective quantification of zopiclone in human hair was developed. The extraction medium and duration were optimized using real eszopiclone-positive hair samples. Specifically, micropulverized extraction with 3.0M ammonium phosphate buffer (pH 8.4) involving salting-out assisted liquid-liquid extraction with acetonitrile was utilized to minimize the degradation of zopiclone and for rapid and facile operation. On the other hand, recovery of the conventional solid-liquid extraction involved overnight soaking in 3.0M ammonium phosphate buffer (pH 8.4) was only 0.58±0.12% of the maximum recovery achieved by the present method due to the decomposition in the phosphate buffer. An excellent chiral separation (Rs=5.0) was achieved using a chiral stationary phase comprising cellulose tris(3,5-dichlorophenylcarbamate) and a volatile mobile phase of 10mM ammonium carbonate (pH 8.0)-acetonitrile (25:75, v/v). Detection was carried out using liquid chromatography/high resolution mass spectrometry (LC/HRMS) with electrospray ionization. A Q Exactive mass spectrometer equipped with a quadrupole-Orbitrap analyzer was used for detection. The concentration of 0.50pg/mg was defined as the lowest limit of quantification using 5mg of hair sample. Using the developed approach, the concentration of eszopiclone in hair after a single 2-mg dose was found to be 441pg/mg, which was higher than all the reported values regarding a single administration of zopiclone. After daily administration of racemic zopiclone (3.75mg/day), the concentrations of (R)-enantiomer and (S)-enantiomer in the black hair were 5.30-8.31ng/mg and 7.96-12.8ng/mg, respectively, and the concentration of the (S)-enantiomer was always higher than that of the (R

  1. Pure chiral optical fibres.

    PubMed

    Poladian, L; Straton, M; Docherty, A; Argyros, A

    2011-01-17

    We investigate the properties of optical fibres made from chiral materials, in which a contrast in optical activity forms the waveguide, rather than a contrast in the refractive index; we refer to such structures as pure chiral fibres. We present a mathematical formulation for solving the modes of circularly symmetric examples of such fibres and examine the guidance and polarisation properties of pure chiral step-index, Bragg and photonic crystal fibre designs. Their behaviour is shown to differ for left- and right-hand circular polarisation, allowing circular polarisations to be isolated and/or guided by different mechanisms, as well as differing from equivalent non-chiral fibres. The strength of optical activity required in each case is quantified.

  2. Chiral quantum dot based materials

    NASA Astrophysics Data System (ADS)

    Govan, Joseph; Loudon, Alexander; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii

    2014-05-01

    Recently, the use of stereospecific chiral stabilising molecules has also opened another avenue of interest in the area of quantum dot (QD) research. The main goal of our research is to develop new types of technologically important quantum dot materials containing chiral defects, study their properties and explore their applications. The utilisation of chiral penicillamine stabilisers allowed the preparation of new water soluble white emitting CdS quantum nanostructures which demonstrated circular dichroism in the band-edge region of the spectrum. It was also demonstrated that all three types of QDs (D-, L-, and Rac penicillamine stabilised) show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. In this work the chiral CdS based quantum nanostructures have also been doped by copper metal ions and new chiral penicilamine stabilized CuS nanoparticles have been prepared and investigated. It was found that copper doping had a strong effect at low levels in the synthesis of chiral CdS nanostructures. We expect that this research will open new horizons in the chemistry of chiral nanomaterials and their application in biotechnology, sensing and asymmetric synthesis.

  3. Neutral meson properties under an external magnetic field in nonlocal chiral quark models

    NASA Astrophysics Data System (ADS)

    Gómez Dumm, D.; Izzo Villafañe, M. F.; Scoccola, N. N.

    2018-02-01

    We study the behavior of neutral meson properties in the presence of a static uniform external magnetic field in the context of nonlocal chiral quark models. The formalism is worked out introducing Ritus transforms of Dirac fields, which allow to obtain closed analytical expressions for π0 and σ meson masses and for the π0 decay constant. Numerical results for these observables are quoted for various parametrizations. In particular, the behavior of the π0 meson mass with the magnetic field is found to be in good agreement with lattice QCD results. It is also seen that the Goldberger-Treiman and Gell-Mann-Oakes-Renner chiral relations remain valid within these models in the presence of the external magnetic field.

  4. Semiclassical fermion pair creation in de Sitter spacetime

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stahl, Clément, E-mail: clement.stahl@icranet.org; Eckhard, Strobel, E-mail: eckhard.strobel@irap-phd.eu; Dipartimento di Fisica, Università di Roma “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome

    2015-12-17

    We present a method to semiclassically compute the pair creation rate of bosons and fermions in de Sitter spacetime. The results in the bosonic case agree with the ones in the literature. We find that for the constant electric field the fermionic and bosonic pair creation rate are the same. This analogy of bosons and fermions in the semiclassical limit is known from several flat spacetime examples.

  5. Micropatterning of cells reveals chiral morphogenesis

    PubMed Central

    2013-01-01

    Invariant left-right (LR) patterning or chirality is critical for embryonic development. The loss or reversal of LR asymmetry is often associated with malformations and disease. Although several theories have been proposed, the exact mechanism of the initiation of the LR symmetry has not yet been fully elucidated. Recently, chirality has been detected within single cells as well as multicellular structures using several in vitro approaches. These studies demonstrated the universality of cell chirality, its dependence on cell phenotype, and the role of physical boundaries. In this review, we discuss the theories for developmental LR asymmetry, compare various in vitro cell chirality model systems, and highlight possible roles of cell chirality in stem cell differentiation. We emphasize that the in vitro cell chirality systems have great promise for helping unveil the nature of chiral morphogenesis in development. PMID:23672821

  6. Observation of three-component fermions in the topological semimetal molybdenum phosphide.

    PubMed

    Lv, B Q; Feng, Z-L; Xu, Q-N; Gao, X; Ma, J-Z; Kong, L-Y; Richard, P; Huang, Y-B; Strocov, V N; Fang, C; Weng, H-M; Shi, Y-G; Qian, T; Ding, H

    2017-06-29

    In quantum field theory, Lorentz invariance leads to three types of fermion-Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.

  7. Entanglement entropies and fermion signs of critical metals

    NASA Astrophysics Data System (ADS)

    Kaplis, N.; Krüger, F.; Zaanen, J.

    2017-04-01

    The fermion sign problem is often viewed as a sheer inconvenience that plagues numerical studies of strongly interacting electron systems. Only recently has it been suggested that fermion signs are fundamental for the universal behavior of critical metallic systems and crucially enhance their degree of quantum entanglement. In this work we explore potential connections between emergent scale invariance of fermion sign structures and scaling properties of bipartite entanglement entropies. Our analysis is based on a wave-function Ansatz that incorporates collective, long-range backflow correlations into fermionic Slater determinants. Such wave functions mimic the collapse of a Fermi liquid at a quantum critical point. Their nodal surfaces, a representation of the fermion sign structure in many-particle configurations space, show fractal behavior up to a length scale ξ that diverges at a critical backflow strength. We show that the Hausdorff dimension of the fractal nodal surface depends on ξ , the number of fermions and the exponent of the backflow. For the same wave functions we numerically calculate the second Rényi entanglement entropy S2. Our results show a crossover from volume scaling, S2˜ℓθ (θ =2 in d =2 dimensions), to the characteristic Fermi-liquid behavior S2˜ℓ lnℓ on scales larger than ξ . We find that volume scaling of the entanglement entropy is a robust feature of critical backflow fermions, independent of the backflow exponent and hence the fractal dimension of the scale invariant sign structure.

  8. Baby Skyrme model and fermionic zero modes

    NASA Astrophysics Data System (ADS)

    Queiruga, J. M.

    2016-09-01

    In this work we investigate some features of the fermionic sector of the supersymmetric version of the baby Skyrme model. We find that, in the background of Bogomol'nyi-Prasad-Sommerfield compact baby Skyrmions, fermionic zero modes are confined to the defect core. Further, we show that, while three Supersymmetry (SUSY) generators are broken in the defect core, SUSY is completely restored outside. We study also the effect of a D-term deformation of the model. Such a deformation allows for the existence of fermionic zero modes and broken SUSY outside the compact defect.

  9. Chirality-dependent cellular uptake of chiral nanocarriers and intracellular delivery of different amounts of guest molecules

    NASA Astrophysics Data System (ADS)

    Kehr, Nermin Seda; Jose, Joachim

    2017-12-01

    We demonstrate the organic molecules loaded and chiral polymers coated periodic mesoporous organosilica (PMO) to generate chiral nanocarriers that we used to study chirality-dependent cellular uptake in serum and serum-free media and the subsequent delivery of different amounts of organic molecules into cells. Our results show that the amount of internalized PMO and thus the transported amount of organic molecules by nanocarrier PMO into cells was chirality dependent and controlled by hard/soft protein corona formation on the PMO surfaces. Therefore, this study demonstrate that chiral porous nanocarriers could potentially be used as advanced drug delivery systems which are able to use the specific chiral surface-protein interactions to influence/control the amount of (bio)active molecules delivered to cells in drug delivery and/or imaging applications.

  10. Quark structure of chiral solitons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dmitri Diakonov

    2004-05-01

    There is a prejudice that the chiral soliton model of baryons is something orthogonal to the good old constituent quark models. In fact, it is the opposite: the spontaneous chiral symmetry breaking in strong interactions explains the appearance of massive constituent quarks of small size thus justifying the constituent quark models, in the first place. Chiral symmetry ensures that constituent quarks interact very strongly with the pseudoscalar fields. The ''chiral soliton'' is another word for the chiral field binding constituent quarks. We show how the old SU(6) quark wave functions follow from the ''soliton'', however, with computable relativistic corrections andmore » additional quark-antiquark pairs. We also find the 5-quark wave function of the exotic baryon Theta+.« less

  11. Self-consistent Models of Strong Interaction with Chiral Symmetry

    DOE R&D Accomplishments Database

    Nambu, Y.; Pascual, P.

    1963-04-01

    Some simple models of (renormalizable) meson-nucleon interaction are examined in which the nucleon mass is entirely due to interaction and the chiral ( gamma {sub 5}) symmetry is "broken'' to become a hidden symmetry. It is found that such a scheme is possible provided that a vector meson is introduced as an elementary field. (auth)

  12. Observing fermionic statistics with photons in arbitrary processes

    PubMed Central

    Matthews, Jonathan C. F.; Poulios, Konstantinos; Meinecke, Jasmin D. A.; Politi, Alberto; Peruzzo, Alberto; Ismail, Nur; Wörhoff, Kerstin; Thompson, Mark G.; O'Brien, Jeremy L.

    2013-01-01

    Quantum mechanics defines two classes of particles-bosons and fermions-whose exchange statistics fundamentally dictate quantum dynamics. Here we develop a scheme that uses entanglement to directly observe the correlated detection statistics of any number of fermions in any physical process. This approach relies on sending each of the entangled particles through identical copies of the process and by controlling a single phase parameter in the entangled state, the correlated detection statistics can be continuously tuned between bosonic and fermionic statistics. We implement this scheme via two entangled photons shared across the polarisation modes of a single photonic chip to directly mimic the fermion, boson and intermediate behaviour of two-particles undergoing a continuous time quantum walk. The ability to simulate fermions with photons is likely to have applications for verifying boson scattering and for observing particle correlations in analogue simulation using any physical platform that can prepare the entangled state prescribed here. PMID:23531788

  13. Terbium-Aspartic Acid Nanocrystals with Chirality-Dependent Tunable Fluorescent Properties.

    PubMed

    Ma, Baojin; Wu, Yu; Zhang, Shan; Wang, Shicai; Qiu, Jichuan; Zhao, Lili; Guo, Daidong; Duan, Jiazhi; Sang, Yuanhua; Li, Linlin; Jiang, Huaidong; Liu, Hong

    2017-02-28

    Terbium-aspartic acid (Tb-Asp) nanocrystals with chirality-dependent tunable fluorescent properties can be synthesized through a facile synthesis method through the coordination between Tb and Asp. Asp with different chirality (dextrorotation/d and levogyration/l) changes the stability of the coordination center following fluorescent absorption/emission ability differences. Compared with l-Asp, d-Asp can coordinate Tb to form a more stable center, following the higher quantum yield and longer fluorescence life. Fluorescence intensity of Tb-Asp linearly increases with increase ratio of d-Asp in the mixed chirality Tb-Asp system, and the fluorescent properties of Tb-Asp nanocrystals can be tuned by adjusting the chirality ratio. Tb-Asp nanocrystals possess many advantage, such as high biocompatibility, without any color in visible light irradiation, monodispersion with very small size, and long fluorescent life. Those characteristics will give them great potential in many application fields, such as low-cost antifake markers and advertisements using inkjet printers or for molds when dispersed in polydimethylsiloxane. In addition, europium can also be used to synthesize Eu-Asp nanoparticles. Importantly, the facile, low-cost, high-yield, mass-productive "green" process provides enormous advantages for synthesis and application of fluorescent nanocrystals, which will have great impact in nanomaterial technology.

  14. Novel Electronic States of Heavy Fermion Compound YbCo2Zn20

    NASA Astrophysics Data System (ADS)

    Honda, Fuminori; Taga, Yuki; Hirose, Yusuke; Yoshiuchi, Shingo; Tomooka, Yoshiharu; Ohya, Masahiro; Sakaguchi, Jyunya; Takeuchi, Tetsuya; Settai, Rikio; Shimura, Yasuyuki; Sakakibara, Toshiro; Sheikin, Ilya; Tanaka, Toshiki; Kubo, Yasunori; Ōnuki, Yoshichika

    2014-04-01

    We studied the heavy fermion compound YbCo2Zn20 with an electronic specific heat coefficient γ ≃ 8000 mJ/(K2·mol) by measuring the de Haas-van Alphen (dHvA) oscillation, Hall effect, magnetic susceptibility, and magnetization at ambient pressure, as well as the electrical resistivity in magnetic fields of up to 320 kOe and at pressures of up to 5 GPa. The detected Fermi surfaces are small in volume, reflecting the small Brillouin zone based on the large cubic lattice constant a = 14.005 Å. The cyclotron effective masses, which were determined from the dHvA experiment, are found to be markedly reduced in magnetic fields. In other words, the detected cyclotron masses of 2.2-8.9 m0 (m0: the rest mass of an electron) at Hav = 117 kOe are enhanced to 100-500 m0 at 0 kOe. By applying pressure, the heavy fermion state disappears at Pc ≃ 1.8 GPa and orders antiferromagnetically for P > Pc. The field-induced antiferroquadrupolar phase, which is observed only for Hallel < 111> in the magnetic field range from HQ = 60 kOe to H'Q = 210 kOe, is found to shift to lower magnetic fields and merge with theantiferromagnetic phase at 4.5 GPa.

  15. Cell Chirality Drives Left-Right Asymmetric Morphogenesis

    PubMed Central

    Inaki, Mikiko; Sasamura, Takeshi; Matsuno, Kenji

    2018-01-01

    Most macromolecules found in cells are chiral, meaning that they cannot be superimposed onto their mirror image. However, cells themselves can also be chiral, a subject that has received little attention until very recently. In our studies on the mechanisms of left-right (LR) asymmetric development in Drosophila, we discovered that cells can have an intrinsic chirality to their structure, and that this “cell chirality” is generally responsible for the LR asymmetric development of certain organs in this species. The actin cytoskeleton plays important roles in the formation of cell chirality. In addition, Myosin31DF (Myo31DF), which encodes Drosophila Myosin ID, was identified as a molecular switch for cell chirality. In other invertebrate species, including snails and Caenorhabditis elegans, chirality of the blastomeres, another type of cell chirality, determines the LR asymmetry of structures in the body. Thus, chirality at the cellular level may broadly contribute to LR asymmetric development in various invertebrate species. Recently, cell chirality was also reported for various vertebrate cultured cells, and studies suggested that cell chirality is evolutionarily conserved, including the essential role of the actin cytoskeleton. Although the biological roles of cell chirality in vertebrates remain unknown, it may control LR asymmetric development or other morphogenetic events. The investigation of cell chirality has just begun, and this new field should provide valuable new insights in biology and medicine. PMID:29666795

  16. Chiral electroweak currents in nuclei

    DOE PAGES

    Riska, D. O.; Schiavilla, R.

    2017-01-10

    Here, the development of the chiral dynamics based description of nuclear electroweak currents is reviewed. Gerald E. (Gerry) Brown’s role in basing theoretical nuclear physics on chiral Lagrangians is emphasized. Illustrative examples of the successful description of electroweak observables of light nuclei obtained from chiral effective field theory are presented.

  17. How gauge covariance of the fermion and boson propagators in QED constrain the effective fermion-boson vertex

    DOE PAGES

    Jia, Shaoyang; Pennington, M. R.

    2016-12-12

    In this paper, we derive the gauge covariance requirement imposed on the QED fermion-photon three-point function within the framework of a spectral representation for fermion propagators. When satisfied, such requirement ensures solutions to the fermion propagator Schwinger-Dyson equation (SDE) in any covariant gauge with arbitrary numbers of spacetime dimensions to be consistent with the Landau-Khalatnikov-Fradkin transformation (LKFT). The general result has been verified by the special cases of three and four dimensions. Additionally, we present the condition that ensures the vacuum polarization is independent of the gauge parameter. Finally, as an illustration, we show how the gauge technique dimensionally regularizedmore » in four dimensions does not satisfy the covariance requirement.« less

  18. Five chiral Cd(II) complexes with dual chiral components: Effect of positional isomerism, luminescence and SHG response

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cheng, Lin, E-mail: lcheng@seu.edu.cn; Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, Southeast University, Nanjing 211189; Wang, Jun

    2015-01-15

    Five chiral Cd(II) complexes with dual chiral components have been synthesized by using a series of (1R,2R)–N{sup 1},N{sup 2}-bis(pyridinylmethyl)cyclohexane-1,2-diamine ligands with different N-positions of pyridyl rings and Cd(NO{sub 3}){sub 2}. The circular dichroism (CD) spectra and second-harmonic generation (SHG) efficiency measurements confirmed that they are of structural chirality in the bulk samples. The luminescent properties indicated that they may have potential applications as optical materials. The formation of discrete mononuclear and binuclear complexes, and one-dimensional chains may be attributed to positional isomerism of the ligands. - Graphical abstract: Five chiral Cd(II) complexes with dual chiral components have been synthesized bymore » using a series of chiral ligands with different N-positions of pyridyl rings. - Highlights: • Five chiral Cd(II) complexes with dual chiral components have been synthesized. • CD spectra and SHG efficiency of the bulk samples have been measured. • The complexes display luminescent properties.« less

  19. ENANTIOMERIC COMPOSITION OF CHIRAL POLYCHLORINATED BIPHENYL ATROPISOMERS IN AQUATIC AND RIPARIAN BIOTA

    EPA Science Inventory

    The enantiomeric composition of polychlorinated biphenyl (PCB) atropisomers was measured in river and riparian biota (fish, bivalves, crayfish, water snakes, barn swallows) from selected sites throughout the United States by using chiral gas chromatography/mass spectrometry. Nonr...

  20. Nanoscale chirality in metal and semiconductor nanoparticles

    PubMed Central

    Thomas, K. George

    2016-01-01

    The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided. PMID:27752651

  1. Nanoscale chirality in metal and semiconductor nanoparticles.

    PubMed

    Kumar, Jatish; Thomas, K George; Liz-Marzán, Luis M

    2016-10-18

    The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided.

  2. Finite density two color chiral perturbation theory revisited

    NASA Astrophysics Data System (ADS)

    Adhikari, Prabal; Beleznay, Soma B.; Mannarelli, Massimo

    2018-06-01

    We revisit two-color, two-flavor chiral perturbation theory at finite isospin and baryon density. We investigate the phase diagram obtained varying the isospin and the baryon chemical potentials, focusing on the phase transition occurring when the two chemical potentials are equal and exceed the pion mass (which is degenerate with the diquark mass). In this case, there is a change in the order parameter of the theory that does not lend itself to the standard picture of first order transitions. We explore this phase transition both within a Ginzburg-Landau framework valid in a limited parameter space and then by inspecting the full chiral Lagrangian in all the accessible parameter space. Across the phase transition between the two broken phases the order parameter becomes an SU(2) doublet, with the ground state fixing the expectation value of the sum of the magnitude squared of the pion and the diquark fields. Furthermore, we find that the Lagrangian at equal chemical potentials is invariant under global SU(2) transformations and construct the effective Lagrangian of the three Goldstone degrees of freedom by integrating out the radial fluctuations.

  3. Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2

    PubMed Central

    Liu, Jinyu; Hu, Jin; Cao, Huibo; Zhu, Yanglin; Chuang, Alyssa; Graf, D.; Adams, D. J.; Radmanesh, S. M. A.; Spinu, L.; Chiorescu, I.; Mao, Zhiqiang

    2016-01-01

    Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm2V−1S−1) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons. PMID:27466151

  4. Enantiomeric separation of six chiral pesticides that contain chiral sulfur/phosphorus atoms by supercritical fluid chromatography.

    PubMed

    Zhang, Lijun; Miao, Yelong; Lin, Chunmian

    2018-03-01

    Six chiral pesticides containing chiral sulfur/phosphorus atoms were separated by supercritical fluid chromatography with supercritical CO 2 as the main mobile phase component. The effect of the chiral stationary phase, different type and concentration of modifiers, column temperature, and backpressure on the separation efficiency was investigated to obtain the appropriate separation condition. Five chiral pesticides (isofenphos-methyl, isocarbophos, flufiprole, fipronil, and ethiprole) were baseline separated under experimental conditions, while isofenphos only obtained partial separation. The Chiralpak AD-3 column showed a better chiral separation ability than others for chiral pesticides containing chiral sulfur/phosphorus atoms. When different modifiers at the same concentration were used, the retention factor of pesticides except flufiprole decreased in the order of isopropanol, ethanol, methanol; meanwhile, the retention factor of flufiprole increased in the order of isopropanol, ethanol, methanol. For a given modifier, the retention factor and resolution decreased on the whole with the increase of its concentration. The enantiomer separation of five chiral pesticides was an "enthalpy-driven" process, and the separation factor decreased as the temperature increased. The backpressure of the mobile phase had little effect on the separation factor and resolution. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Broadband reflection of polymer-stabilized chiral nematic liquid crystals induced by a chiral azobenzene compound.

    PubMed

    Chen, Xingwu; Wang, Ling; Chen, Yinjie; Li, Chenyue; Hou, Guoyan; Liu, Xin; Zhang, Xiaoguang; He, Wanli; Yang, Huai

    2014-01-21

    A chiral nematic liquid crystal-photopolymerizable monomer-chiral azobenzene compound composite was prepared and then polymerized under UV irradiation. The reflection wavelength of the composite can be extended to cover the 1000-2400 nm range and also be adjusted to the visible light region by controlling the concentration of chiral compounds.

  6. Review of the fermionic dark matter model applied to galactic structures

    NASA Astrophysics Data System (ADS)

    Krut, A.; Argüelles, C. R.; Rueda, J.; Ruffini, R.

    2015-12-01

    Baryonic components (e.g. bulge and disk) of galactic structures are assumed to be embedded in an isothermal dark matter halo of fermionic nature. Besides the Pauli principle only gravitational interaction is considered. Using the underlying Fermi-Dirac phase space distribution, typical of collisionless relaxation processes, it yields an one-parameter family of scaled solutions which reproduces the observed flat rotation curves in galaxies, and additionally predicts a degenerate core through their centers. In order to provide the right DM halo properties of galaxies a set of four parameters (particle mass, degeneracy parameter at the galactic center, central density and the velocity dispersion) is necessary. The more general density profile shows three regimes depending on radius: an almost uniform very dense quantum core followed by a steep fall, a plateau in the diluted regime and a Boltzmannian tail representing the halo. In contrast to purely Boltzmannian configurations the fermionic DM model containing a quantum core allows to determine the particle mass. We show that the quantum core can be well approximated by a polytrope of index n = 3/2, while the halo can be perfectly described by an isothermal sphere with a halo scale length radius equal to approximately 3/4 of the King-radius.

  7. Review of the fermionic dark matter model applied to galactic structures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Krut, A.; Argüelles, C. R.; Rueda, J.

    2015-12-17

    Baryonic components (e.g. bulge and disk) of galactic structures are assumed to be embedded in an isothermal dark matter halo of fermionic nature. Besides the Pauli principle only gravitational interaction is considered. Using the underlying Fermi-Dirac phase space distribution, typical of collisionless relaxation processes, it yields an one-parameter family of scaled solutions which reproduces the observed flat rotation curves in galaxies, and additionally predicts a degenerate core through their centers. In order to provide the right DM halo properties of galaxies a set of four parameters (particle mass, degeneracy parameter at the galactic center, central density and the velocity dispersion)more » is necessary. The more general density profile shows three regimes depending on radius: an almost uniform very dense quantum core followed by a steep fall, a plateau in the diluted regime and a Boltzmannian tail representing the halo. In contrast to purely Boltzmannian configurations the fermionic DM model containing a quantum core allows to determine the particle mass. We show that the quantum core can be well approximated by a polytrope of index n = 3/2, while the halo can be perfectly described by an isothermal sphere with a halo scale length radius equal to approximately 3/4 of the King-radius.« less

  8. Observation of three-component fermions in the topological semimetal molybdenum phosphide

    NASA Astrophysics Data System (ADS)

    Lv, B. Q.; Feng, Z.-L.; Xu, Q.-N.; Gao, X.; Ma, J.-Z.; Kong, L.-Y.; Richard, P.; Huang, Y.-B.; Strocov, V. N.; Fang, C.; Weng, H.-M.; Shi, Y.-G.; Qian, T.; Ding, H.

    2017-06-01

    In quantum field theory, Lorentz invariance leads to three types of fermion—Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.

  9. Chiral amplification and sensing of chirality with lyotropic chromonic liquid crystals

    NASA Astrophysics Data System (ADS)

    Srinivasarao, Mohan; Park, Jung Ok; Fu, Jinxin; Nayani, Karthik; Chang, Rui

    Due to the anisotropic elastic properties of lyotropic chromonic liquid crystals (LCLCs), a spontaneously twisted chiral structure has been reported in the achiral LCLCs system under cylindrical confinement. It is found that the handedness of chirality could be biased with a minute amount of a chiral additive. The entire system becomes ``homochiral'' and takes on the handedness of the additive. When 1% by weight of L-glutamic acid was added to LCLCs in a cylinder, the LCLC sbecomes homochiral and possesses giant optical rotation. We explore the mechanism for this based on the ``sergeants-and-soldiers'' and the ``majority-rule'' principles known for organic molecular systems.

  10. Pion momentum distributions in the nucleon in chiral effective theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burkardt, Matthias R.; Hendricks, K. S.; Ji, Cheung Ryong

    2013-03-01

    We compute the light-cone momentum distributions of pions in the nucleon in chiral effective theory using both pseudovector and pseudoscalar pion--nucleon couplings. For the pseudovector coupling we identifymore » $$\\delta$$-function contributions associated with end-point singularities arising from the pion-nucleon rainbow diagrams, as well as from pion tadpole diagrams which are not present in the pseudoscalar model. Gauge invariance is demonstrated, to all orders in the pion mass, with the inclusion of Weinberg-Tomozawa couplings involving operator insertions at the $$\\pi NN$$ vertex. The results pave the way for phenomenological applications of pion cloud models that are manifestly consistent with the chiral symmetry properties of QCD.« less

  11. The Chiral and Angular Momentum Content of the ρ-Meson

    NASA Astrophysics Data System (ADS)

    Glozman, L. Ya.; Lang, C. B.; Limmer, M.

    2010-01-01

    It is possible to define and calculate in a gauge-invariant manner the chiral as well as the partial wave content of the quark-antiquark Fock component of a meson in the infrared, where mass is generated. Using the variational method and a set of interpolators that span a complete chiral basis we extract in a lattice QCD Monte Carlo simulation with n f = 2 dynamical light quarks the orbital angular momentum and spin content of the ρ-meson. We obtain in the infrared a simple 3 S 1 component as a leading component of the ρ-meson with a small admixture of the 3 D 1 partial wave, in agreement with the SU(6) flavor-spin symmetry.

  12. Status of the chiral magnetic effect and collisions of isobars

    DOE PAGES

    Koch, Volker; Schlichting, Soeren; Skokov, Vladimir; ...

    2017-04-30

    Here, we examine the current theoretical and experimental status of the chiral magnetic effect. We discuss possible future strategies for resolving uncertainties in interpretation including recommendations for theoretical work, recommendations for measurements based on data collected in the past five years, and recommendations for beam use in the coming years of RHIC. We then investigate the case for colliding nuclear isobars (nuclei with the same mass but different charge) and find the case compelling. We recommend that a program of nuclear isobar collisions to isolate the chiral magnetic effect from background sources be placed as a high priority item inmore » the strategy for completing the RHIC mission.« less

  13. q -deformed statistics and the role of light fermionic dark matter in SN1987A cooling

    NASA Astrophysics Data System (ADS)

    Guha, Atanu; J, Selvaganapathy; Das, Prasanta Kumar

    2017-01-01

    The light dark matter (≃1 - 30 MeV ) particles pair produced in electron-positron annihilation e-e+→ γ χ χ ¯ inside the supernova core can take away the energy released in the supernova SN1987A explosion. Working within the formalism of q -deformed statistics [with the average value of the supernovae core temperature (fluctuating) being TS N=30 MeV ] and using the Raffelt's criterion on the emissivity for any new channel ɛ ˙ (e+e-→χ χ ¯ )≤1 019 erg g-1 s-1 , we find that as the deformation parameter q changes from 1.0 (undeformed scenario) to 1.1 (deformed scenario), the lower bound on the scale Λ of the dark matter effective theory varies from 3.3 ×1 06 TeV to 3.2 ×1 07 TeV for a dark matter fermion of mass mχ=30 MeV . Using the optical depth criteria on the free streaming of the dark matter fermion, we find the lower bound on Λ ˜1 08 TeV for mχ=30 MeV . In a scenario, where the dark matter fermions are pair produced in the outermost sector of the supernova core [with radius 0.9 Rc≤r ≤Rc , Rc(=10 km ) being the supernova core radius or the radius of protoneutron star], we find that the bound on Λ (˜3 ×1 07 TeV ) obtained from SN cooling criteria (Raffelt's criteria) is comparable with the bound obtained from free streaming (optical depth criterion) for light fermion dark matter of mass mχ=10 - 30 MeV .

  14. Macdonald index and chiral algebra

    NASA Astrophysics Data System (ADS)

    Song, Jaewon

    2017-08-01

    For any 4d N = 2 SCFT, there is a subsector described by a 2d chiral algebra. The vacuum character of the chiral algebra reproduces the Schur index of the corresponding 4d theory. The Macdonald index counts the same set of operators as the Schur index, but the former has one more fugacity than the latter. We conjecture a prescription to obtain the Macdonald index from the chiral algebra. The vacuum module admits a filtration, from which we construct an associated graded vector space. From this grading, we conjecture a notion of refined character for the vacuum module of a chiral algebra, which reproduces the Macdonald index. We test this prescription for the Argyres-Douglas theories of type ( A 1 , A 2 n ) and ( A 1 , D 2 n+1) where the chiral algebras are given by Virasoro and \\widehat{su}(2) affine Kac-Moody algebra. When the chiral algebra has more than one family of generators, our prescription requires a knowledge of the generators from the 4d.

  15. Macdonald index and chiral algebra

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Song, Jaewon

    For any 4dN = 2 SCFT, there is a subsector described by a 2d chiral algebra. The vacuum character of the chiral algebra reproduces the Schur index of the corresponding 4d theory. The Macdonald index counts the same set of operators as the Schur index, but the former has one more fugacity than the latter. Here, we conjecture a prescription to obtain the Macdonald index from the chiral algebra. The vacuum module admits a filtration, from which we construct an associated graded vector space. From this grading, we conjecture a notion of refined character for the vacuum module of a chiral algebra, which reproduces the Macdonald index. We test this prescription for the Argyres-Douglas theories of type (A 1, A 2n) and (A 1, D 2n+1) where the chiral algebras are given by Virasoro andmore » $$ˆ\\atop{su}$$(2) affine Kac-Moody algebra. When the chiral algebra has more than one family of generators, our prescription requires a knowledge of the generators from the 4d.« less

  16. Macdonald index and chiral algebra

    DOE PAGES

    Song, Jaewon

    2017-08-10

    For any 4dN = 2 SCFT, there is a subsector described by a 2d chiral algebra. The vacuum character of the chiral algebra reproduces the Schur index of the corresponding 4d theory. The Macdonald index counts the same set of operators as the Schur index, but the former has one more fugacity than the latter. Here, we conjecture a prescription to obtain the Macdonald index from the chiral algebra. The vacuum module admits a filtration, from which we construct an associated graded vector space. From this grading, we conjecture a notion of refined character for the vacuum module of a chiral algebra, which reproduces the Macdonald index. We test this prescription for the Argyres-Douglas theories of type (A 1, A 2n) and (A 1, D 2n+1) where the chiral algebras are given by Virasoro andmore » $$ˆ\\atop{su}$$(2) affine Kac-Moody algebra. When the chiral algebra has more than one family of generators, our prescription requires a knowledge of the generators from the 4d.« less

  17. Strong lensing by fermionic dark matter in galaxies

    NASA Astrophysics Data System (ADS)

    Gómez, L. Gabriel; Argüelles, C. R.; Perlick, Volker; Rueda, J. A.; Ruffini, R.

    2016-12-01

    It has been shown that a self-gravitating system of massive keV fermions in thermodynamic equilibrium correctly describes the dark matter (DM) distribution in galactic halos (from dwarf to spiral and elliptical galaxies) and that, at the same time, it predicts a denser quantum core towards the center of the configuration. Such a quantum core, for a fermion mass in the range of 50 keV ≲m c2≲345 keV , can be an alternative interpretation of the central compact object in Sgr A*, traditionally assumed to be a black hole (BH). We present in this work the gravitational lensing properties of this novel DM configuration in nearby Milky-Way-like spiral galaxies. We describe the lensing effects of the pure DM component both on halo scales, where we compare them to the effects of the Navarro-Frenk-White and the nonsingular isothermal sphere DM models, and near the galaxy center, where we compare them with the effects of a Schwarzschild BH. For the particle mass leading to the most compact DM core, m c2≈1 02 keV , we draw the following conclusions. At distances r ≳20 pc from the center of the lens the effect of the central object on the lensing properties is negligible. However, we show that measurements of the deflection angle produced by the DM distribution in the outer region at a few kpc, together with rotation curve data, could help to discriminate between different DM models. In the inner regions 1 0-6≲r ≲20 pc , the lensing effects of a DM quantum core alternative to the BH scenario becomes a theme of an analysis of unprecedented precision which is challenging for current technological developments. We show that at distances ˜1 0-4 pc strong lensing effects, such as multiple images and Einstein rings, may occur. Large differences in the deflection angle produced by a DM central core and a central BH appear at distances r ≲1 0-6 pc ; in this regime the weak-field formalism is no longer applicable and the exact general-relativistic formula has to be used

  18. Excited meson spectroscopy with two chirally improved quarks

    NASA Astrophysics Data System (ADS)

    Engel, G.; Lang, C. B.; Mohler, D.; Limmer, M.; Schäfer, A.

    The excited isovector meson spectrum is explored using two chirally improved dynamical quarks. Seven ensembles, with pion masses down to \\approx 250 MeV are discussed and used for extrapolations to the physical point. Strange mesons are investigated using partially quenched s-quarks. Using the variational method, we extract excited states in several channels and most of the results are in good agreement with experiment.

  19. Fluctuations of a q-deformed fermion gas

    NASA Astrophysics Data System (ADS)

    Zeng, Qijun; Ge, Jing; Luo, Yongsong

    2018-05-01

    The theory of q-deformed fermions is one of the theories of q-deformed oscillators. Within the framework of this theory and the traditional fluctuation theory, we investigate fluctuations of q-deformed fermion gas and obtain the expressions of fluctuations of the internal energy U, the particle number N and the correlation of fluctuations of the two physical quantities above. Further numerical calculation reveals that fluctuations of such a system have some interesting and particular features. We consider that this work may provide much insight into the theory of q fermions, and may also be helpful for the theory of q-deformed oscillators.

  20. Electromagnetic wave propagation through a dielectric-chiral interface and through a chiral slab

    NASA Technical Reports Server (NTRS)

    Bassiri, S.; Papas, C. H.; Engheta, N.

    1988-01-01

    The reflection from and transmission through a semiinfinite chiral medium are analyzed by obtaining the Fresnel equations in terms of parallel- and perpendicular-polarized modes, and a comparison is made with results reported previously. The chiral medium is described electromagnetically by the constitutive relations D = (epsilon)E+i(gamma)B and H = i(gamma)E+(1/mu)B. The constants epsilon, mu and gamma are real and have values that are fixed by the size, the shape, and the spatial distribution of the elements that collectively compose the medium. The conditions are obtained for the total internal reflection of the incident wave from the interface and for the existence of the Brewster angle. The effects of the chirality on the polarization and the intensity of the reflected wave from the chiral half-space are discussed and illustrated by using the Stokes parameters. The propagation of electromagnetic wave through an infinite slab of chiral medium is formulated for oblique incidence and solved analytically for the case of normal incidence.