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.
Chiral gravitational waves from chiral fermions
NASA Astrophysics Data System (ADS)
Anber, Mohamed M.; Sabancilar, Eray
2017-07-01
We report on a new mechanism that leads to the generation of primordial chiral gravitational waves, and hence, the violation of the parity symmetry in the Universe. We show that nonperturbative production of fermions with a definite helicity is accompanied by the generation of chiral gravitational waves. This is a generic and model-independent phenomenon that can occur during inflation, reheating and radiation eras, and can leave imprints in the cosmic microwave background polarization and may be observed in future ground- and space-based interferometers. We also discuss a specific model where chiral gravitational waves are generated via the production of light chiral fermions during pseudoscalar inflation.
Spontaneous compactification and chiral fermions
NASA Astrophysics Data System (ADS)
Frampton, Paul H.; Yamamoto, Katsuji
The question is addressed of which chiral fermions survive in spontaneously compactified solutions of the generalized Einstein-Yang-Mills field equations for higher even space-time dimensions. First, we study the allowed fermion representations of SU( N) which have no gauge or gravitational chiral anomalies in arbitrary even dimension and show how to find all such representations for the case of totally antisymmetric SU( N) tensors. Second, we look explicitly at monopole-induced spontaneous compactification in six dimensions; here, interesting chiral fermions in four dimensions do not occur easily but instead require highly artificial assignments of quantum numbers under the U(1) gauge group associated with the monopole. Finally, we consider instanton-induced spontaneous compactification in eight dimensions; for this case, we may readily obtain acceptable chiral fermions in four dimensions, including Georgi's three-family SU(11) model.
Chiral fermions in asymptotically safe quantum gravity.
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.
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.
Quantum electrodynamics with complex fermion mass
McKellar, B.J.H. . School of Physics); Wu, D.D. . School of Physics Academia Sinica, Beijing, BJ . Inst. of High Energy Physics Superconducting Super Collider Lab., Dallas, TX )
1991-08-01
The quantum electrodynamics (QED) with a complex fermion mass -- that is, a fermion mass with a chiral phase -- is restudied, together with its chirally rotated version. We show how fake electric dipole moment can be obtained and how to avoid it. 10 refs.
Fermion masses through four-fermion condensates
Ayyar, Venkitesh; Chandrasekharan, Shailesh
2016-10-12
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 two 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.
Fermion masses through four-fermion condensates
Ayyar, Venkitesh; Chandrasekharan, Shailesh
2016-10-12
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
Chiral Scars in Chaotic Dirac Fermion Systems
NASA Astrophysics Data System (ADS)
Xu, Hongya; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2013-02-01
Do relativistic quantum scars in classically chaotic systems possess unique features that are not shared by nonrelativistic quantum scars? We report a class of relativistic quantum scars in massless Dirac fermion systems whose phases return to the original values or acquire a 2π change only after circulating twice about some classical unstable periodic orbits. We name such scars chiral scars, the successful identification of which has been facilitated tremendously by our development of an analytic, conformal-mapping-based method to calculate an unprecedentedly large number of eigenstates with high accuracy. Our semiclassical theory indicates that the physical origin of chiral scars can be attributed to a combined effect of chirality intrinsic to massless Dirac fermions and the geometry of the underlying classical orbit.
Gauge covariant fermion propagator in quenched, chirally symmetric quantum electrodynamics
Roberts, C.D.; Dong, Z.; Munczek, H.J.
1995-08-01
The chirally symmetric solution of the massless, quenched, Dyson-Schwinger equation (DSE) for the fermion propagator in three- and four-dimensional quantum electrodynamics was obtained. The DSEs are a valuable nonperturbative tool for studying field theories. In recent years a good deal of progress was made in addressing the limitations of the DSE approach in the study of Abelian gauge theories. Key to this progress is an understanding of the role of the dressed fermion/gauge-boson vertex in ensuring gauge covariance and multiplicative renormalizability of the solution of the fermion DSE. The solutions we obtain are manifestly gauge covariant and a general gauge covariance constraint on the fermion/gauge-boson vertex is presented, which motivates a vertex Ansatz that, for the first time, both satisfies the Ward identity when the fermion self-mass is zero and ensures gauge covariance of the fermion propagator. This research facilitates gauge-invariant, nonperturbative studies of continuum quantum electrodynamics and has already been used by others in studies of the chiral phase transition.
One-loop chiral perturbation theory with two fermion representations
DeGrand, Thomas; Golterman, Maarten; Neil, Ethan T.; Shamir, Yigal
2016-07-11
In this study, we develop chiral perturbation theory for chirally broken theories with fermions in two different representations of the gauge group. Any such theory has a nonanomalous singlet U(1)_{A} symmetry, yielding an additional Nambu-Goldstone boson when spontaneously broken. We calculate the next-to-leading order corrections for the pseudoscalar masses and decay constants, which include the singlet Nambu-Goldstone boson, as well as for the two condensates. The results can be generalized to more than two representations.
One-loop chiral perturbation theory with two fermion representations
DeGrand, Thomas; Golterman, Maarten; Neil, Ethan T.; ...
2016-07-11
In this study, we develop chiral perturbation theory for chirally broken theories with fermions in two different representations of the gauge group. Any such theory has a nonanomalous singlet U(1)A symmetry, yielding an additional Nambu-Goldstone boson when spontaneously broken. We calculate the next-to-leading order corrections for the pseudoscalar masses and decay constants, which include the singlet Nambu-Goldstone boson, as well as for the two condensates. The results can be generalized to more than two representations.
One-loop chiral perturbation theory with two fermion representations
DeGrand, Thomas; Golterman, Maarten; Neil, Ethan T.; Shamir, Yigal
2016-07-11
In this study, we develop chiral perturbation theory for chirally broken theories with fermions in two different representations of the gauge group. Any such theory has a nonanomalous singlet U(1)_{A} symmetry, yielding an additional Nambu-Goldstone boson when spontaneously broken. We calculate the next-to-leading order corrections for the pseudoscalar masses and decay constants, which include the singlet Nambu-Goldstone boson, as well as for the two condensates. The results can be generalized to more than two representations.
Topological susceptibility in staggered fermion chiral perturbation theory
Billeter, Brian; DeTar, Carleton; Osborn, James
2004-10-01
The topological susceptibility of the vacuum in quantum chromodynamics has been simulated numerically using the Asqtad improved staggered fermion formalism. At nonzero lattice spacing, the residual fermion doublers (fermion tastes) in the staggered fermion formalism give contributions to the susceptibility that deviate from conventional continuum chiral perturbation theory. In this brief report, we estimate the taste-breaking artifact and compare it with results of recent simulations, finding that it accounts for roughly half of the scaling violation.
Overlap fermions on a twisted mass sea
NASA Astrophysics Data System (ADS)
Schaefer, Stefan
2006-12-01
We present first results of a mixed action project. We analyze gauge configurations generated with two flavors of dynamical twisted mass fermions. Neuberger's overlap Dirac operator is used for the valence sector. The various choices in the setup of the simulation are discussed. We employ chiral perturbation theory to describe the effects of using different actions in the sea and valence sector at non-zero lattice spacing.
Fermion mass without symmetry breaking
NASA Astrophysics Data System (ADS)
Catterall, Simon
2016-01-01
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 [1]. 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. Massless and massive phases appear to be separated by a continuous phase transition.
Fermion mass without symmetry breaking
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.
A streamlined method for chiral fermions on the lattice
Bodwin, G.T. . High Energy Physics Div.); Kovacs, E.V. )
1992-11-10
We discussed the use of renormalization counterterms to restore the chiral gauge symmetry in a lattice theory of Wilson fermions. We show that a large class of counterterms can be implemented automatically by making a simple modification to the fermion determinant.
A streamlined method for chiral fermions on the lattice
Bodwin, G.T.; Kovacs, E.V.
1992-11-10
We discussed the use of renormalization counterterms to restore the chiral gauge symmetry in a lattice theory of Wilson fermions. We show that a large class of counterterms can be implemented automatically by making a simple modification to the fermion determinant.
Fermion self-energy in magnetized chirally asymmetric QED matter
NASA Astrophysics Data System (ADS)
Rybalka, D. O.
2016-12-01
The fermion self-energy is calculated for a cold QED plasma with chiral chemical potential in a magnetic field. It is found that a momentum shift parameter dynamically generated in such a plasma leads to a modification of the chiral magnetic effect current. It is argued that the momentum shift parameter can be relevant for the evolution of magnetic field in the chirally asymmetric primordial plasma in the early Universe.
Fermion mass without symmetry breaking
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.
NASA Astrophysics Data System (ADS)
Mace, Mark; Mueller, Niklas; Schlichting, Sören; Sharma, Sayantan
2017-02-01
We present a real-time lattice approach to study the nonequilibrium dynamics of vector and axial charges in S U (N )×U (1 ) gauge theories. Based on a classical description of the non-Abelian and Abelian gauge fields, we include dynamical fermions and develop operator definitions for (improved) Wilson and overlap fermions that allow us to study real-time manifestations of the axial anomaly from first principles. We present a first application of this approach to anomalous transport phenomena such as the chiral magnetic effect (CME) and the chiral separation effect (CSE) by studying the dynamics of fermions during and after a S U (N ) sphaleron transition in the presence of a U (1 ) magnetic field. We investigate the fermion mass and magnetic field dependence of the suggested signatures of the CME and the CSE and point out some important aspects which need to be accounted for in the macroscopic description of anomalous transport phenomena.
Bose symmetry and chiral decomposition of 2D fermionic determinants
NASA Astrophysics Data System (ADS)
Abreu, E. M. C.; Banerjee, R.; Wotzasek, C.
1998-01-01
We show in a precise way, either in the fermionic or its bosonized version, that Bose symmetry provides a systematic way to carry out the chiral decomposition of the two-dimensional fermionic determinant. Interpreted properly, we show that there is no obstruction of this decomposition to gauge invariance, as is usually claimed. Finally, a new way of interpreting the Polyakov-Wiegman identity is proposed.
Three-dimensional Majorana fermions in chiral superconductors.
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 PrOs4Sb12 and related materials as promising candidates for nonunitary chiral superconductors hosting three-dimensional Majorana fermions.
Three-dimensional Majorana fermions in chiral superconductors
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
Cavity-induced chiral states of fermionic quantum gases
NASA Astrophysics Data System (ADS)
Sheikhan, Ameneh; Brennecke, Ferdinand; Kollath, Corinna
2016-04-01
We investigate ultracold fermions placed into an optical cavity and subjected to optical lattices which confine the atoms to ladder structures. A transverse running-wave laser beam induces together with the dynamical cavity field a two-photon Raman-assisted tunneling process with spatially dependent phase imprint along the rungs of the ladders. We identify the steady states which can occur by the feedback mechanism between the cavity field and the atoms. We find the spontaneous emergence of a finite cavity field amplitude which leads to an artificial magnetic field felt by the fermionic atoms. These form a chiral insulating or chiral liquid state carrying a chiral current. We explore the rich state diagram as a function of the power of the transverse laser beam, the atomic filling, and the phase imprint during the cavity-induced tunneling. Both a sudden onset or a slow exponential activation with the transverse laser power of the self-organized chiral states can occur.
Gravitational contribution to fermion masses
NASA Astrophysics Data System (ADS)
Tiemblo, A.; Tresguerres, R.
2005-08-01
In the context of a non-linear gauge theory of the Poincaré group, we show that covariant derivatives of Dirac fields include a coupling to the translational connections, manifesting itself in the matter action as a universal background mass contribution to fermions.
Pion Decay Constant, Z{sub A} and Chiral Log from Overlap Fermions
Shao-Jing Dong; Terrence Draper; Ivan Horvath; Frank X. Lee; Jianbo Zhang
2002-03-01
We report our calculation of the pion decay constant f{sub {pi}}, the axial renormalization constant Z{sub A}, and the quenched chiral logarithms from the overlap fermions. The calculation is done on a quenched 20{sup 4} lattice at a=0.148 fm using tree level tadpole improved gauge action. The smallest pion mass we reach is about 280 MeV. The lattice size is about 4 times the Compton wavelength of the lowest mass pion.
Chiral symmetry breaking from Ginsparg-Wilson fermions
NASA Astrophysics Data System (ADS)
Hernándes, Pilar; Jansen, Karl; Lellouch, Laurent
We calculate the large-volume and small-mass dependences of the quark condensate in quenched QCD using Neuberger's operator. We find good agreement with the predictions of quenched chiral perturbation theory, enabling a determination of the chiral lagrangian parameter Σ, up to a multiplicative renormalization.
Influence of boson mass on chiral phase transition in QED3
NASA Astrophysics Data System (ADS)
Feng, Hong-tao; Wang, Xiu-Zhen; Yu, Xin-hua; Zong, Hong-shi
2016-08-01
Based on the truncated Dyson-Schwinger equations for the fermion propagator with N fermion flavors at zero temperature, the chiral phase transition of quantum electrodynamics in 2 +1 dimensions (QED3 ) with boson mass—which is obtained via the Anderson-Higgs mechanism—is investigated. In the chiral limit, we find that the critical behavior of QED3 with a massless boson is different from that with a massive boson: the chiral phase transition in the presence of a nonzero boson mass reveals the typical second-order phase transition, at either the critical boson mass or a critical number of fermion flavors, while for a vanishing boson mass it exhibits a higher than second-order phase transition at the critical number of fermion flavors. Furthermore, it is shown that the system undergoes a crossover behavior from a small number of fermion flavors or boson mass to its larger one beyond the chiral limit.
Flavor symmetries and fermion masses
Rasin, Andrija
1994-04-01
We introduce several ways in which approximate flavor symmetries act on fermions and which are consistent with observed fermion masses and mixings. Flavor changing interactions mediated by new scalars appear as a consequence of approximate flavor symmetries. We discuss the experimental limits on masses of the new scalars, and show that the masses can easily be of the order of weak scale. Some implications for neutrino physics are also discussed. Such flavor changing interactions would easily erase any primordial baryon asymmetry. We show that this situation can be saved by simply adding a new charged particle with its own asymmetry. The neutrality of the Universe, together with sphaleron processes, then ensures a survival of baryon asymmetry. Several topics on flavor structure of the supersymmetric grand unified theories are discussed. First, we show that the successful predictions for the Kobayashi-Maskawa mixing matrix elements, V_{ub}/V_{cb} = √m_{u}/m_{c} and V_{td}/V_{ts} = √m_{d}/m_{s}, are a consequence of a large class of models, rather than specific properties of a few models. Second, we discuss how the recent observation of the decay β → sγ constrains the parameter space when the ratio of the vacuum expectation values of the two Higgs doublets, tanβ, is large. Finally, we discuss the flavor structure of proton decay. We observe a surprising enhancement of the branching ratio for the muon mode in SO(10) models compared to the same mode in the SU(5) model.
Majorana Fermions in Chiral Topological Ferromagnetic Nanowires
NASA Astrophysics Data System (ADS)
Dumitrescu, Eugen; Roberts, Brenden; Tewari, Sumanta; Sau, Jay D.
2015-03-01
Motivated by a recent experiment in which zero-bias peaks have been observed in STM experiments performed on chains of magnetic atoms on a superconductor, we show that a multichannel ferromagnetic wire deposited on a spin-orbit coupled superconducting substrate can realize a non-trivial chiral topological superconducting state with Majorana bound states localized at the wire ends. The non-trivial topological state occurs for generic parameters requiring no fine tuning, at least for very large exchange spin splitting in the wire. We theoretically obtain the signatures which appear in the presence of an arbitrary number of Majorana modes in multi-wire systems incorporating the role of finite temperature, finite potential barrier at the STM tip, and finite wire length. These signatures are presented in terms of spatial profiles of STM differential conductance which clearly reveal zero energy Majorana end modes and the prediction of a multiple Majorana based fractional Josephson effect. Co-author: S. Das Sarma. Work supported by AFOSR (FA9550-13-1-0045) at Clemson University and by LPS-CMTC and JQI-NSF-PFC at the University of Maryland.
Entanglement Hamiltonians for Chiral Fermions with Zero Modes
NASA Astrophysics Data System (ADS)
Klich, Israel; Vaman, Diana; Wong, Gabriel
2017-09-01
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.
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.
Mass-induced transition in fermion number
Aragao de Carvalho, C.; Pureza, J. M.
1989-05-15
We show that if we increase the mass of fermions in interaction with a topological (kink) scalar background in 1+1 dimensions, the fractional fermion number of the system will eventually vanish. The transition is sharp and corresponds to the disappearance of localized states from the spectrum of a Dirac operator which is exactly solvable. Possible applications to different physical systems are discussed.
Hadron Masses and Quark Condensate from Overlap Fermions
NASA Astrophysics Data System (ADS)
Liu, K. F.; Dong, S. J.; Lee, F. X.; Zhang, J. B.
We present results on hadron masses and quark condensate from Neuberger's overlap fermion. The scaling and chiral properties and finite volume effects from this new Dirac operator are studied. We find that the generalized Gell-Mann-Oakes-Renner relation is well satisfied down to the physical u and d quark mass range. We find that in the range of the lattice spacing we consider, the π and ϱ masses at a fixed mπ/ mϱ ratio have weak O( a2) dependence.
Nonperturbative results for the mass dependence of the QED fermion determinant
Fry, M. P.
2010-05-15
The fermion determinant in four-dimensional quantum electrodynamics in the presence of O(2)xO(3) symmetric background gauge fields with a nonvanishing global chiral anomaly is considered. It is shown that the leading mass singularity of the determinant's nonperturbative part is fixed by the anomaly. It is also shown that for a large class of such fields there is at least one value of the fermion mass at which the determinant's nonperturbative part reduces to its noninteracting value.
Chiral fermions on 2D curved space-times
NASA Astrophysics Data System (ADS)
Loran, Farhang
2017-06-01
The theory of free Majorana-Weyl spinors is the prototype of conformal field theory in two dimensions in which the gravitational anomaly and the Weyl anomaly obstruct extending the flat space-time results to curved backgrounds. In this paper, we investigate a quantization scheme in which the short distance singularity in the two-point function of chiral fermions on a two-dimensional curved space-time is given by the Green’s function corresponding to the classical field equation. We compute the singular term in the Green’s function explicitly and observe that the short distance limit is not well-defined in general. We identify constraints on the geometry which are necessary to resolve this problem. On such special backgrounds, the theory has locally c = 1 2 conformal symmetry.
NASA Astrophysics Data System (ADS)
Hoelbling, Christian; Zielinski, Christian
2016-07-01
We follow up on a suggestion by Adams and construct explicit domain wall fermion operators with staggered kernels. We compare different domain wall formulations, namely the standard construction as well as Boriçi's modified and Chiu's optimal construction, utilizing both Wilson and staggered kernels. In the process, we generalize the staggered kernels to arbitrary even dimensions and introduce both truncated and optimal staggered domain wall fermions. Some numerical investigations are carried out in the (1 +1 )-dimensional setting of the Schwinger model, where we explore spectral properties of the bulk, effective and overlap Dirac operators in the free-field case, on quenched thermalized gauge configurations and on smooth topological configurations. We compare different formulations using the effective mass, deviations from normality and violations of the Ginsparg-Wilson relation as measures of chirality.
Lattice super-Yang-Mills using domain wall fermions in the chiral limit
Giedt, Joel; Brower, Richard; Catterall, Simon; Fleming, George T.; Vranas, Pavlos
2009-01-15
Lattice N=1 super-Yang-Mills formulated using Ginsparg-Wilson fermions provides a rigorous nonperturbative definition of the continuum theory that requires no fine-tuning as the lattice spacing is reduced to zero. Domain wall fermions are one explicit scheme for achieving this and using them we have performed large-scale Monte Carlo simulations of the theory for gauge group SU(2). We have measured the gaugino condensate, static potential, Creutz ratios, and residual mass for several values of the domain wall separation L{sub s}, four-dimensional lattice volume, and two values of the bare gauge coupling. With this data we are able to extrapolate the gaugino condensate to the chiral limit, to express it in physical units, and to establish important benchmarks for future studies of super-Yang-Mills on the lattice.
Chiral and continuum extrapolation of partially-quenched hadron masses
Chris Allton; Wes Armour; Derek Leinweber; Anthony Thomas; Ross Young
2005-09-29
Using the finite-range regularization (FRR) of chiral effective field theory, the chiral extrapolation formula for the vector meson mass is derived for the case of partially-quenched QCD. We re-analyze the dynamical fermion QCD data for the vector meson mass from the CP-PACS collaboration. A global fit, including finite lattice spacing effects, of all 16 of their ensembles is performed. We study the FRR method together with a naive polynomial approach and find excellent agreement ({approx}1%) with the experimental value of M{sub {rho}} from the former approach. These results are extended to the case of the nucleon mass.
Kawarabayashi, Tohru; Honda, Takahiro; Aoki, Hideo; Hatsugai, Yasuhiro
2013-12-04
The effect of disorder on the Landau levels of massless Dirac fermions is examined for the cases with and without the fermion doubling. To tune the doubling a tight-binding model having a complex transfer integral is adopted to shift the energies of two Dirac cones, which is theoretically proposed earlier and realizable in cold atoms in an optical lattice. In the absence of the fermion doubling, the n = 0 Landau level is shown to exhibit an anomalous sharpness even if the disorder is uncorrelated in space (i.e., large K-K' scattering). This anomaly occurs when the disorder respects the chiral symmetry of the Dirac cone.
Vortex anomaly in low-dimensional fermionic condensates: Quantum confinement breaks chirality
NASA Astrophysics Data System (ADS)
Chen, Yajiang; Shanenko, A. A.; Peeters, F. M.
2014-02-01
Chiral fermions are responsible for low-temperature properties of vortices in fermionic condensates, both superconducting (charged) and superfluid (neutral). One of the most striking consequences of this fact is that the core of a single-quantum vortex collapses at low temperatures, T →0 (i.e., the Kramer-Pesch effect for superconductors), due to the presence of chiral quasiparticles in the vortex-core region. We show that the situation changes drastically for fermionic condensates confined in quasi-one-dimensional and quasi-two-dimensional geometries. Here quantum confinement breaks the chirality of in-core fermions. As a result, instead of the ultimate shrinking, the core of a single-quantum vortex extends at low temperatures, and the condensate profile surprisingly mimics the multiquantum vortex behavior. Our findings are relevant for nanoscale superconductors, such as recent metallic nanoislands on silicon, and also for ultracold superfluid Fermi gases in cigar-shaped and pancake-shaped atomic traps.
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.
The topological structures in strongly coupled QGP with chiral fermions on the lattice
NASA Astrophysics Data System (ADS)
Sharma, Sayantan; Dick, Viktor; Karsch, Frithjof; Laermann, Edwin; Mukherjee, Swagato
2016-12-01
The nature of chiral phase transition for two flavor QCD is an interesting but unresolved problem. One of the most intriguing issues is whether or not the anomalous U(1) symmetry in the flavor sector is effectively restored along with the chiral symmetry. This may determine the universality class of the chiral phase transition. Since the physics near the chiral phase transition is essentially non-perturbative, we employ first principles lattice techniques to address this issue. We use overlap fermions, which have exact chiral symmetry on the lattice, to probe the anomalous U(1) symmetry violation of 2+1 flavor dynamical QCD configurations with domain wall fermions. The latter also optimally preserves chiral and flavor symmetries on the lattice, since it is known that the remnant chiral symmetry of the light quarks influences the scaling of the chiral condensate in the crossover transition region. We observe that the anomalous U(1) is not effectively restored in the chiral crossover region. We perform a systematic study of the finite size and cut-off effects since the signals of U(1) violation are sensitive to it. We also provide a glimpse of the microscopic topological structures of the QCD medium that are responsible for the strongly interacting nature of the quark gluon plasma phase. We study the effect of these microscopic constituents through our first calculations for the topological susceptibility of QCD at finite temperature, which could be a crucial input for the equation of state for anomalous hydrodynamics.
Mixtures of Ultracold Fermions with Unequal Masses
NASA Astrophysics Data System (ADS)
de Melo, Carlos A. R. Sa
2008-05-01
The quantum phases of ultracold fermions with unequal masses are discussed in continuum and lattice models for a wide variety of mixtures which exhibit Feshbach resonances, e.g., mixtures of ^6Li and ^40K. The evolution of superfluidity from the Bardeen-Cooper-Schrieffer (BCS) to the Bose-Einstein condensation (BEC) regime in the continuum is analyzed as a function of scattering parameter, population imbalance and mass anisotropy. In the continuum case, regions corresponding to normal, phase-separated or coexisting uniform-superfluid/excess-fermion phases are identified and the possibility of topological phase transitions is discussed [1]. For optical lattices, the phase diagrams as a function of interaction strength, population imbalance, filling fraction and tunneling parameters are presented [2]. In addition to the characteristic phases of the continuum, a series of insulating phases emerge in the phase diagrams of optical lattices, including a Bose-Mott insulator (BMI), a Fermi-Pauli insulator (FPI), a phase-separated BMI/FPI mixture, and a Bose-Fermi checkerboard (BFC) phase. Lastly, the effects of harmonic traps and the emergence of unusual shell structures are discussed for mixtures of fermions with unequal masses. [1] M. Iskin, and C. A. R. S' a de Melo, Phys. Rev. Lett 97, 100404 (2006); [2] M. Iskin, and C. A. R. S' a de Melo, Phys. Rev. Lett. 99, 080403 (2007).
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.
Effects of rotation and boundaries on chiral symmetry breaking of relativistic fermions
NASA Astrophysics Data System (ADS)
Chernodub, M. N.; Gongyo, Shinya
2017-05-01
In order to avoid unphysical causality-violating effects, any rigidly rotating system must be bounded in directions transverse to the axis of rotation. We demonstrate that this requirement implies substantial dependence of properties of the relativistically rotating system on the boundary conditions. We consider a system of interacting fermions described by the Nambu-Jona-Lasinio model in a space bounded by the cylindrical surface of the finite radius. In order to confine the fermions inside the cylinder, we impose "chiral" MIT boundary conditions on its surface. These boundary conditions are parametrized by a continuous chiral angle Θ . We find that, at any value of Θ , the chiral restoration temperature Tc decreases as a quadratic function of the angular frequency Ω . However, the position and the slope of the critical curve Tc=Tc(Ω ) in the phase diagram depend noticeably on the value of the chiral angle.
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
Ayala, Alejandro; Bashir, Adnan; Gutierrez, Enif; Raya, Alfredo; Sanchez, Angel
2010-09-01
We study chiral symmetry breaking for relativistic fermions, described by a parity-violating Lagrangian in 2+1-dimensions, in the presence of a heat bath and a uniform external magnetic field. Working within their four-component formalism allows for the inclusion of both parity-even and -odd mass terms. Therefore, we can define two types of fermion antifermion condensates. For a given value of the magnetic field, there exist two different critical temperatures which would render one of these condensates identically zero, while the other would survive. Our analysis is completely general: it requires no particular simplifying hierarchy among the energy scales involved, namely, bare masses, field strength, and temperature. However, we do reproduce some earlier results, obtained or anticipated in literature, corresponding to special kinematical regimes for the parity conserving case. Relating the chiral condensate to the one-loop effective Lagrangian, we also obtain the magnetization and the pair production rate for different fermion species in a uniform electric field through the replacement B{yields}-iE.
Analysis of a lattice Wess-Zumino scheme for chiral fermions
Bodwin, G.T.; Kovacs, E.V.
1988-01-01
We show that the four-dimensional version of the chiral lattice fermion scheme proposed by Aoki and Funakubo and Kashiwa leads, in the continuum limit, to a transverse, but quadratically divergent, contribution to the effective vacuum polarization. Hence, the scheme does not make sense without the addition of counterterms beyond those that are required in the continuum theory. 10 refs., 3 figs.
Chiral magnetic effect of Weyl fermions and its applications to cubic noncentrosymmetric metals
NASA Astrophysics Data System (ADS)
Tewari, Sumanta; Goswami, Pallab
2014-03-01
When the right and the left handed Weyl points are separated in energy, they give rise to a non-dissipative charge current along the direction of a uniform applied magnetic field, even in the absence of an external electric field. This effect is known as the chiral magnetic effect and is a hallmark of the underlying chiral anomaly of the Weyl fermions. According to the linearized continuum theory of Weyl fermions, the induced current is proportional to the magnetic field strength and the energy separation with a universal coefficient e2 /h2 . By considering a generic tight binding model for the cubic non-centrosymmetric metals, we show that such a system naturally supports a set of Weyl points, which are separated in energies. We also show the existence of the chiral magnetic effect for generic band parameters, and recover the universal result of the continuum Weyl fermions for a restricted parameter regime. Our work proves that the cubic non-centrosymmetric metals can serve as suitable platforms for realizing Weyl fermions and the exotic chiral elctrodynamic phenomena, which have promising technological applications. Work supported by the NSF Cooperative Agreement No. DMR- 0654118, the State of Florida, the U. S. Department of Energy, NSF (PHY-1104527) and AFOSR (FA9550-13-1-0045).
A new approach to chiral fermions on the lattice
Bodwin, G.T. ); Kovacs, E.V. )
1990-11-14
We wish to describe a method for formulating, on the lattice, field theories that contain Dirac particles with chiral couplings to gauge fields. As is well-known, the most straight-forward lattice transcription of the continuum action for a Dirac particle leads to the doubling problem: for every particle of a given chirality in the continuum theory, there appear on the lattice, in d dimensions, 2{sup d} particles, with equal numbers of particles of left- and right-handed chirality. No-go theorems, state that it is impossible to eliminate the doubling problem and still maintain an exact chiral gauge symmetry. Rather than follow an approach that attempts to circumvent the no-go theorems we, instead, explore the possibility of abandoning exact chiral symmetry.
Observation of chiral edge states with neutral fermions in synthetic Hall ribbons.
Mancini, M; Pagano, G; Cappellini, G; Livi, L; Rider, M; Catani, J; Sias, C; Zoller, P; Inguscio, M; Dalmonte, M; Fallani, L
2015-09-25
Chiral edge states are a hallmark of quantum Hall physics. In electronic systems, they appear as a macroscopic consequence of the cyclotron orbits induced by a magnetic field, which are naturally truncated at the physical boundary of the sample. Here we report on the experimental realization of chiral edge states in a ribbon geometry with an ultracold gas of neutral fermions subjected to an artificial gauge field. By imaging individual sites along a synthetic dimension, encoded in the nuclear spin of the atoms, we detect the existence of the edge states and observe the edge-cyclotron orbits induced during quench dynamics. The realization of fermionic chiral edge states opens the door for edge state interferometry and the study of non-Abelian anyons in atomic systems. Copyright © 2015, American Association for the Advancement of Science.
Signatures of the Adler–Bell–Jackiw chiral anomaly in a Weyl fermion semimetal
Zhang, Cheng-Long; Xu, Su-Yang; Belopolski, Ilya; Yuan, Zhujun; Lin, Ziquan; Tong, Bingbing; Bian, Guang; Alidoust, Nasser; Lee, Chi-Cheng; Huang, Shin-Ming; Chang, Tay-Rong; Chang, Guoqing; Hsu, Chuang-Han; Jeng, Horng-Tay; Neupane, Madhab; Sanchez, Daniel S.; Zheng, Hao; Wang, Junfeng; Lin, Hsin; Zhang, Chi; Lu, Hai-Zhou; Shen, Shun-Qing; Neupert, Titus; Zahid Hasan, M.; Jia, Shuang
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 field 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.
Signatures of the Adler-Bell-Jackiw chiral anomaly in a Weyl fermion semimetal.
Zhang, Cheng-Long; Xu, Su-Yang; Belopolski, Ilya; Yuan, Zhujun; Lin, Ziquan; Tong, Bingbing; Bian, Guang; Alidoust, Nasser; Lee, Chi-Cheng; Huang, Shin-Ming; Chang, Tay-Rong; Chang, Guoqing; Hsu, Chuang-Han; Jeng, Horng-Tay; Neupane, Madhab; Sanchez, Daniel S; Zheng, Hao; Wang, Junfeng; Lin, Hsin; Zhang, Chi; Lu, Hai-Zhou; Shen, Shun-Qing; Neupert, Titus; Zahid Hasan, M; Jia, Shuang
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 field strength. We present systematically detailed data and careful analyses, which allow us to exclude other possible origins of the observed negative magnetoresistance. 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.
QCD phase transition with chiral quarks and physical quark masses.
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.
Localization and mass spectra of fermions on symmetric and asymmetric thick branes
Liu Yuxiao; Fu, C.-E; Zhao Li; Duan Yishi
2009-09-15
A three-parameter (positive odd integer s, thickness factor {lambda}, and asymmetry factor a) family of asymmetric thick brane solutions in five dimensions were constructed from a two-parameter (s and {lambda}) family of symmetric ones in by R. Guerrero, R. O. Rodriguez, and R. Torrealba in [Phys. Rev. D 72, 124012 (2005).]. The values s=1 and s{>=}3 correspond to single branes and double branes, respectively. These branes have very rich inner structure. In this paper, by presenting the mass-independent potentials of Kaluza-Klein (KK) modes in the corresponding Schroedinger equations, we investigate the localization and mass spectra of fermions on the symmetric and asymmetric thick branes in an anti-de Sitter background. In order to analyze the effect of gravity-fermion interaction (i.e., the effect of the inner structure of the branes) and scalar-fermion interaction to the spectrum of fermion KK modes, we consider three kinds of typical kink-fermion couplings. The spectra of left chiral fermions for these couplings consist of a bound zero mode and a series of gapless continuous massive KK modes, some discrete bound KK modes including zero mode (exist mass gaps), and a series of continuous massive KK modes, infinite discrete bound KK modes, respectively. The structures of the spectra are investigated in detail.
Chiral Majorana fermion modes in a quantum anomalous Hall insulator-superconductor structure.
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.
Interacting fermions in rotation: chiral symmetry restoration, moment of inertia and thermodynamics
NASA Astrophysics Data System (ADS)
Chernodub, M. N.; Gongyo, Shinya
2017-01-01
We study rotating fermionic matter at finite temperature in the framework of the Nambu-Jona-Lasinio model. In order to respect causality the rigidly rotating system must be bound by a cylindrical boundary with appropriate boundary conditions that confine the fermions inside the cylinder. We show the finite geometry with the MIT boundary conditions affects strongly the phase structure of the model leading to three distinct regions characterized by explicitly broken (gapped), partially restored (nearly gapless) and spontaneously broken (gapped) phases at, respectively, small, moderate and large radius of the cylinder. The presence of the boundary leads to specific steplike irregularities of the chiral condensate as functions of coupling constant, temperature and angular frequency. These steplike features have the same nature as the Shubnikov-de Haas oscillations with the crucial difference that they occur in the absence of both external magnetic field and Fermi surface. At finite temperature the rotation leads to restoration of spontaneously broken chiral symmetry while the vacuum at zero temperature is insensitive to rotation ("cold vacuum cannot rotate"). As the temperature increases the critical angular frequency decreases and the transition becomes softer. A phase diagram in angular frequency-temperature plane is presented. We also show that at fixed temperature the fermion matter in the chirally restored (gapless) phase has a higher moment of inertia compared to the one in the chirally broken (gapped) phase.
Fermion Chiral Anomaly and Atiyah-Patodi Index for Spherical Spacetime Boundaries.
NASA Astrophysics Data System (ADS)
Schmidt, Jeffrey Robert
We study the structure of the fermion chiral anomaly in four-dimensional Euclidean spacetime bounded by a spherical surface via the Atiyah-Patodi-Singer Index Theorem. The significance of the index theorem in physics is discussed through examples taken from high energy and solid state physics. The proof of the index theorem is then detailed in a relatively pedestrian manner. Two exactly soluble examples involving self-dual gauge fields are presented and the anomaly explicitly evaluated. These two cases consist of a fermion interacting with a U(1) electromagnetic field and an SU(2) instanton, respectively.
Lee, Minchul; Choi, Mahn-Soo
2014-08-15
We investigate the mesoscopic resistor-capacitor circuit consisting of a quantum dot coupled to spatially separated Majorana fermion modes in a chiral topological superconductor. We find substantially enhanced relaxation resistance due to the nature of Majorana fermions, which are their own antiparticles and are composed of particle and hole excitations in the same abundance. Further, if only a single Majorana mode is involved, the zero-frequency relaxation resistance is completely suppressed due to a destructive interference. As a result, the Majorana mode opens an exotic dissipative channel on a superconductor which is typically regarded as dissipationless due to its finite superconducting gap.
Improving chiral property of domain-wall fermions by reweighting method
Ishikawa, T.; Aoki, Y.; Izubuchi, T.
2009-07-25
The reweighting method is applied to improve the chiral property of domain-wall fermions. One way to achieve this is to enlarge L{sub s}, the size of fifth dimension, which controls the size of the induced chiral symmetry breaking. While this is a type of reweighting method for shifting the action parameter, it seems non-trivial since this reweighting means change of the five dimensional lattice volume. In this report, we address issues in this direction of reweighting and evaluate its effectiveness.
Hermele, Michael; Gurarie, Victor; Rey, Ana Maria
2009-09-25
We study Mott insulators of fermionic alkaline earth atoms, described by Heisenberg spin models with enhanced SU(N) symmetry. In dramatic contrast to SU(2) magnetism, more than two spins are required to form a singlet. On the square lattice, the classical ground state is highly degenerate and magnetic order is thus unlikely. In a large-N limit, we find a chiral spin liquid ground state with topological order and Abelian fractional statistics. We discuss its experimental detection. Chiral spin liquids with non-Abelian anyons may also be realizable with alkaline earth atoms.
NASA Astrophysics Data System (ADS)
Nataf, Pierre; Lajkó, Miklós; Wietek, Alexander; Penc, Karlo; Mila, Frédéric; Läuchli, Andreas M.
2016-10-01
We show that, in the presence of a π /2 artificial gauge field per plaquette, Mott insulating phases of ultracold fermions with SU (N ) symmetry and one particle per site generically possess an extended chiral phase with intrinsic topological order characterized by an approximate ground space of N low-lying singlets for periodic boundary conditions, and by chiral edge states described by the SU(N ) 1 Wess-Zumino-Novikov-Witten conformal field theory for open boundary conditions. This has been achieved by extensive exact diagonalizations for N between 3 and 9, and by a parton construction based on a set of N Gutzwiller projected fermionic wave functions with flux π /N per triangular plaquette. Experimental implications are briefly discussed.
The chiral phase transition of QED{sub 3} around the critical number of fermion flavors
Yin, Pei-lin; Cui, Zhu-fang; Feng, Hong-tao; Zong, Hong-shi
2014-09-15
At zero temperature and density, the nature of the chiral phase transition in QED{sub 3} with N{sub f} massless fermion flavors is investigated. To this end, in Landau gauge, we numerically solve the coupled Dyson–Schwinger equations for the fermion and boson propagator within the bare and simplified Ball–Chiu vertices separately. It is found that, in the bare vertex approximation, the system undergoes a high-order continuous phase transition from the Nambu–Goldstone phase into the Wigner phase when the number of fermion flavors N{sub f} reaches the critical number N{sub f,c}, while the system exhibits a typical characteristic of second-order phase transition for the simplified Ball–Chiu vertex.
Chiral fermions and anomaly cancellation on orbifolds with Wilson lines and flux
NASA Astrophysics Data System (ADS)
Buchmuller, Wilfried; Dierigl, Markus; Ruehle, Fabian; Schweizer, Julian
2015-11-01
We consider six-dimensional supergravity compactified on orbifolds with Wilson lines and bulk flux. Torus Wilson lines are decomposed into Wilson lines around the orbifold fixed points, and twisted boundary conditions of matter fields are related to fractional localized flux. Both, orbifold singularities and flux lead to chiral fermions in four dimensions. We show that in addition to the standard bulk and fixed point anomalies the Green-Schwarz term also cancels the four-dimensional anomaly induced by the flux background. The two axions contained in the antisymmetric tensor field both contribute to the cancellation of the four-dimensional anomaly and the generation of a vector boson mass via the Stueckelberg mechanism. An orthogonal linear combination of the axions remains massless and couples to the gauge field in the standard way. Furthermore, we construct convenient expressions for the wave functions of the zero modes and relate their multiplicity and behavior at the fixed points to the bulk flux quanta and the Wilson lines.
Pentaquark masses in chiral perturbation theory
Mohta, Vivek
2004-12-01
Heavy baryon chiral perturbation theory for pentaquarks is applied beyond leading order. The mass splitting in the pentaquark antidecuplet is calculated up to next-to-next-to-leading order in the absence of other exotic multiplets nearby in mass. An expansion in the coupling of the antidecuplet to nonexotic baryons simplifies calculations and makes the pentaquark masses insensitive to the pentaquark-nucleon mass difference. It is assumed that no other pentaquark multiplets are nearby in the mass spectrum. The possibility of determining coupling constants in the chiral Lagrangian on the lattice is discussed. Both positive and negative parities are considered.
Why the overlap formula does not lead to chiral fermions
NASA Astrophysics Data System (ADS)
Golterman, Maarten; Shamir, Yigal
1996-03-01
We describe a conceptually simple, but important test for the overlap approach to the construction of lattice chiral gauge theories. We explain the equivalence of the overlap formula with a certain waveguide model for a simple set of gauge configurations (the trivial orbit). This equivalence is helpful in carrying out the test, and casts serious doubts on the viability of the overlap approach. A recent note by Narayanan and Neuberger which points out a mistake in our previous work is irrelevant in this context.
Dynamics of domain-wall Dirac fermions on a topological insulator: A chiral fermion beam splitter
NASA Astrophysics Data System (ADS)
Hammer, René; Pötz, Walter
2013-12-01
The intersection of two ferromagnetic domain walls placed on the surface of topological insulators provides a one-way beam splitter for domain-wall Dirac fermions. Based on an analytic expression for a static two-soliton magnetic texture we perform a systematic numerical study of the propagation of Dirac wave packets along such intersections. A single-cone staggered-grid finite difference lattice scheme is employed in the numerical analysis. It is shown that the angle of intersection plays a decisive role in determining the splitting ratio of the fermion beam. For a nonrectangular intersection, the width and, to a lesser extent, the type of domain walls, e.g., Bloch or Néel, determine the properties of the splitter. As the ratio between domain-wall width and transverse localization length of the Dirac fermion is increased its propagation behavior changes from quantum-mechanical (wavelike) to classical ballistic (particlelike). An electric gate placed near the intersection offers a dynamic external control knob for adjusting the splitting ratio.
Simulation of quantum chromodynamics on the lattice with exactly chiral lattice fermions
NASA Astrophysics Data System (ADS)
Aoki, Sinya; Chiu, Ting-Wai; Cossu, Guido; Feng, Xu; Fukaya, Hidenori; Hashimoto, Shoji; Hsieh, Tung-Han; Kaneko, Takashi; Matsufuru, Hideo; Noaki, Jun-Ichi; Onogi, Tetsuya; Shintani, Eigo; Takeda, Kouhei
2012-09-01
Numerical simulation of the low-energy dynamics of quarks and gluons is now feasible based on the fundamental theory of strong interaction, i.e. quantum chromodynamics (QCD). With QCD formulated on a 4D hypercubic lattice (called lattice QCD or LQCD), one can simulate the QCD vacuum and hadronic excitations on the vacuum using teraflop-scale supercomputers, which have become available in the last decade. A great deal of work has been done on this subject by many groups around the world; in this article we summarize the work done by the JLQCD and TWQCD collaborations since 2006. These collaborations employ Neuberger's overlap fermion formulation, which preserves the exact chiral and flavor symmetries on the lattice, unlike other lattice fermion formulations. Because of this beautiful property, numerical simulation of the formulation can address fundamental questions on the QCD vacuum, such as the microscopic structure of the quark-antiquark condensate in the chirally broken phase of QCD and its relation to SU(3) gauge field topology. Tests of the chiral effective theory, which is based on the assumption that the chiral symmetry is spontaneously broken in the QCD vacuum, can be performed, including the pion-loop effect test. For many other phenomenological applications, we adopt the all-to-all quark propagator technique, which allows us to compute various correlation functions without substantial extra cost. The benefit of this is not only that the statistical signal is improved but that disconnected quark-loop diagrams can be calculated. Using this method combined with the overlap fermion formulation, we study a wide range of physical quantities that are of both theoretical and phenomenological interest.
Leading chiral logarithms for the nucleon mass
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.
Signatures of the Adler–Bell–Jackiw chiral anomaly in a Weyl fermion semimetal
Zhang, Cheng-Long; Xu, Su-Yang; Belopolski, Ilya; Yuan, Zhujun; Lin, Ziquan; Tong, Bingbing; Bian, Guang; Alidoust, Nasser; Lee, Chi-Cheng; Huang, Shin-Ming; Chang, Tay-Rong; Chang, Guoqing; Hsu, Chuang-Han; Jeng, Horng-Tay; Neupane, Madhab; Sanchez, Daniel S.; Zheng, Hao; Wang, Junfeng; Lin, Hsin; Zhang, Chi; Lu, Hai-Zhou; Shen, Shun-Qing; Neupert, Titus; Zahid Hasan, M.; Jia, Shuang
2016-01-01
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 field strength. We present systematically detailed data and careful analyses, which allow us to exclude other possible origins of the observed negative magnetoresistance. 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. PMID:26911701
Signatures of the Adler–Bell–Jackiw chiral anomaly in a Weyl fermion semimetal
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
Fermionic Fields with Mass Dimension One as Supersymmetric Extension of the O'Raifeartaigh Model
NASA Astrophysics Data System (ADS)
Wunderle, Kai E.
The objective of this thesis is to derive a supersymmetric Lagrangian for fermionic fields with mass dimension one and to discuss their coupling to the O'Raifeartaigh model which is the simplest model permitting supersymmetry breaking. In addition it will be shown that eigenspinors of the charge conjugation operator (ELKO) exhibit a different transformation behaviour under discrete symmetries than previously assumed. The calculations confirm that ELKO spinors are not eigenspinors of the parity operator and satisfy (CPT)2 = -- I which identifies them as representation of a nonstandard Wigner class. However, it is found that ELKO spinors transform symmetrically under parity instead of the previously assumed asymmetry. Furthermore, it is demonstrated that ELKO spinors transform asymmetrically under time reversal which is opposite to the previously reported symmetric behaviour. These changes affect the (anti)commutation relations that are satisfied by the operators acting on ELKO spinors. Therefore, ELKO spinors satisfy the same (anti)commutation relations as Dirac spinors, even though they belong to two different representations of the Lorentz group. Afterwards, a supersymmetric model for fermionic fields with mass dimension one based on a general superfield with one spinor index is formulated. It includes the systematic derivation of all associated chiral and anti-chiral superfields up to third order in covariant derivatives. Starting from these fundamental superfields a supersymmetric on-shell Lagrangian that contains a kinetic term for the fermionic fields with mass dimension one is constructed. This on-shell Lagrangian is subsequently used to derive the on-shell super-current and to successfully formulate a consistent second quantisation for the component fields. In addition, the Hamiltonian in position space that corresponds to the supersymmetric Lagrangian is calculated. As the Lagrangian is by construction supersymmetric and the second quantisation of the
NASA Astrophysics Data System (ADS)
Ghazaryan, Areg; Chakraborty, Tapash
2015-12-01
We have studied the influence of electron-electron interaction on the fractal butterfly spectrum of Dirac fermions in biased bilayer graphene in the fractional quantum Hall effect (FQHE) regime. We demonstrate that the butterfly spectrum exhibits remarkable phase transitions between the FQHE gap and the butterfly gap for chiral electrons in bilayer graphene, when the periodic potential strength or the bias voltage is varied. We also find that, in addition to those phase transitions, by varying the bias voltage one can effectively control the periodic potential strength experienced by the electrons. The electron-electron interaction causes the butterfly spectrum to exhibit new gaps inside the Bloch sub-bands not found in the single-particle case. We expect that both the observed phase transition and other new features in the butterfly spectrum of interacting Dirac fermions will be of great interest to researchers from diverse fields.
Calculation of the strange quark mass using domain wall fermions
Blum, Tom; Soni, Amarjit; Wingate, Matthew
1999-12-01
We present a first calculation of the strange quark mass using domain wall fermions. This paper contains an overview of the domain wall discretization and a pedagogical presentation of the perturbative calculation necessary for computing the mass renormalization. We combine the latter with numerical simulations to estimate the strange quark mass. Our final result in the quenched approximation is 95(26) MeV in the MS scheme at a scale of 2 GeV. We find that domain wall fermions have a small perturbative mass renormalization, similar to Wilson quarks, and exhibit good scaling behavior. (c) 1999 The American Physical Society.
Converting heat to electricity by a graphene stripe with heavy chiral fermions
NASA Astrophysics Data System (ADS)
Shafranjuk, Serhii E.
2014-04-01
A conversion of thermal energy into electricity is considered in the electrically polarized graphene stripes with zigzag edges where the heavy chiral fermion (HCF) states are formed. The stripes are characterized by a high electric conductance G e and by a significant Seebeck coefficient S. The electric current in the stripes is induced due to a non-equilibrium thermal injection of "hot" electrons. This thermoelectric generation process might be utilized for building of thermoelectric generators with an exceptionally high figure of merit ZδT ≫ 1 and with an appreciable electric power densities ~1 MW/cm2.
Heavy fermions. Chirality density wave of the "hidden order" phase in URu₂Si₂.
Kung, H-H; Baumbach, R E; Bauer, E D; Thorsmølle, V K; Zhang, W-L; Haule, K; Mydosh, J A; Blumberg, G
2015-03-20
A second-order phase transition in a physical system is associated with the emergence of an "order parameter" and a spontaneous symmetry breaking. The heavy fermion superconductor URu2Si2 has a "hidden order" (HO) phase below the temperature of 17.5 kelvin; the symmetry of the associated order parameter has remained ambiguous. Here we use polarization-resolved Raman spectroscopy to specify the symmetry of the low-energy excitations above and below the HO transition. We determine that the HO parameter breaks local vertical and diagonal reflection symmetries at the uranium sites, resulting in crystal field states with distinct chiral properties, which order to a commensurate chirality density wave ground state. Copyright © 2015, American Association for the Advancement of Science.
Metal-insulator transition in two-dimensional random fermion systems of chiral symmetry classes
NASA Astrophysics Data System (ADS)
König, E. J.; Ostrovsky, P. M.; Protopopov, I. V.; Mirlin, A. D.
2012-05-01
Field-theoretical approach to Anderson localization in 2D disordered fermionic systems of chiral symmetry classes (BDI, AIII, CII) is developed. Important representatives of these symmetry classes are random hopping models on bipartite lattices at the band center. As was found by Gade and Wegner two decades ago within the sigma-model formalism, quantum interference effects in these classes are absent to all orders of perturbation theory. We demonstrate that the quantum localization effects emerge when the theory is treated nonperturbatively. Specifically, they are controlled by topological vortexlike excitations of the sigma models. We derive renormalization-group equations including these nonperturbative contributions. Analyzing them, we find that the 2D disordered systems of chiral classes undergo a metal-insulator transition driven by topologically induced Anderson localization. We also show that the Wess-Zumino and Z2 θ terms on surfaces of 3D topological insulators (in classes AIII and CII, respectively) overpower the vortex-induced localization.
Hadron Properties with FLIC Fermions
James Zanotti; Wolodymyr Melnitchouk; Anthony Williams; J Zhang
2003-07-01
The Fat-Link Irrelevant Clover (FLIC) fermion action provides a new form of nonperturbative O(a)-improvement in lattice fermion actions offering near continuum results at finite lattice spacing. It provides computationally inexpensive access to the light quark mass regime of QCD where chiral nonanalytic behavior associated with Goldstone bosons is revealed. The motivation and formulation of FLIC fermions, its excellent scaling properties and its low-lying hadron mass phenomenology are presented.
Fermion Mass Renormalization Using Time-dependent Relativistic Quantum Mechanics
NASA Astrophysics Data System (ADS)
Kutnink, Timothy; Santrach, Amelia; Hocket, Sarah; Barcus, Scott; Petridis, Athanasios
2015-10-01
The time-dependent electromagnetically self-coupled Dirac equation is solved numerically by means of the staggered-leap-frog algorithm with refcecting boundary conditions. The stability region of the method versus the interaction strength and the spatial-grid size over time-step ratio is established. The expectation values of several dynamic operators are then evaluated as functions of time. These include the fermion and electromagnetic energies and the fermion dynamic mass, as the self-interacting spinors are no longer mass-eigenfunctions. There is a characteristic, non-exponential, oscillatory dependence leading to asymptotic constants of these expectation values. In the case of the fermion mass this amounts to renormalization. The dependence of the expectation values on the spatial-grid size is evaluated in detail. Statistical regularization is proposed to remove the grid-size dependence.
Charm and strange quark masses and fD s from overlap fermions
NASA Astrophysics Data System (ADS)
Yang, Yi-Bo; Chen, Ying; Alexandru, Andrei; Dong, Shao-Jing; Draper, Terrence; Gong, Ming; Lee, Frank X.; Li, Anyi; Liu, Keh-Fei; Liu, Zhaofeng; Lujan, Michael
2015-08-01
We use overlap fermions as valence quarks to calculate meson masses in a wide quark mass range on the 2 +1 -flavor domain-wall fermion gauge configurations generated by the RBC and UKQCD Collaborations. The well-defined quark masses in the overlap fermion formalism and the clear valence quark mass dependence of meson masses observed from the calculation facilitate a direct derivation of physical current quark masses through a global fit to the lattice data, which incorporates O (a2) and O (mc4a4) corrections, chiral extrapolation, and quark mass interpolation. Using the physical masses of Ds, Ds* and J /ψ as inputs, Sommer's scale parameter r0 and the masses of charm quark and strange quark in the MS ¯ scheme are determined to be r0=0.465 (4 )(9 ) fm , mcMS ¯(2 GeV )=1.118 (6 )(24 ) GeV (or mcMS ¯(mc)=1.304 (5 )(20 ) GeV ), and msMS ¯(2 GeV )=0.101 (3 )(6 ) GeV , respectively. Furthermore, we observe that the mass difference of the vector meson and the pseudoscalar meson with the same valence quark content is proportional to the reciprocal of the square root of the valence quark masses. The hyperfine splitting of charmonium, MJ /ψ-Mηc , is determined to be 119(2)(7) MeV, which is in good agreement with the experimental value. We also predict the decay constant of Ds to be fDs=254 (2 )(4 ) MeV . The masses of charmonium P -wave states χc 0 , χc 1 and hc are also in good agreement with experiments.
Lorentz violation bounds from torsion trace fermion sector and galaxy M 51 data and chiral dynamos
NASA Astrophysics Data System (ADS)
Garcia de Andrade, L. C.
2017-06-01
Earlier we have computed a Lorentz violation (LV) bound for torsion terms via galactic dynamos and found bounds similar to the one obtained by Kostelecky et al. (Phys Rev Lett 100:111102, 2008) which is of the order of 10^{-31} GeV. Their result was found making use of the axial torsion vector in terms of Dirac spinors and minimal torsion coupling in flat space-time of fermions. In this paper, a torsion dynamo equation obtained using the variation of the torsion trace and galaxy M51 data of 500 pc are used to place an upper bound of 10^{-26} GeV in LV, which agrees with the one by Kostelecky and his group using an astrophysical framework background. Their lowest bound was obtained in earth laboratory using dual masers. One of the purposes of this paper is to apply the Faraday self-induction magnetic equation, recently extended to torsioned space-time, by the author to show that it lends support to physics in Riemann-Cartan space-time, in several distinct physical backgrounds. Backreaction magnetic effects are used to obtain the LV bounds. Previously Bamba et al. (JCAP 10:058, 2012) have used the torsion trace in their teleparallel investigation of the IGMF, with the argument that the torsion trace leads to less weaker effects than the other irreducible components of the torsion tensor. LV is computed in terms of a chiral-torsion-like current in the new dynamo equation analogous to the Dvornikov and Semikoz dynamo equation with chiral magnetic currents. Making use of the chiral-torsion dynamo equation we estimate the LV bounds in the early universe to be of the order of 10^{-24} GeV, which was the order of the charged-lepton sector. Our main result is that it is possible to obtain more stringent bounds than the ones found in the fermion sector of astrophysics in the new revised 2017 data table for CPT and Lorentz violation by Kostelecky and Mewes. They found in several astrophysical backgrounds, orders of magnitude such as 10^{-24} and 10^{-23} GeV which are not so
Fermion masses without symmetry breaking in two spacetime dimensions
NASA Astrophysics Data System (ADS)
BenTov, Yoni
2015-07-01
I study the prospect of generating mass for symmetry-protected fermions without breaking the symmetry that forbids quadratic mass terms in the Lagrangian. I focus on 1+1 spacetime dimensions in the hope that this can provide guidance for interacting fermions in 3+1 dimensions. I first review the SO(8) Gross-Neveu model and emphasize a subtlety in the triality transformation. Then I focus on the " m = 0" manifold of the SO(7) Kitaev-Fidkowski model. I argue that this theory exhibits a phenomenon similar to "parity doubling" in hadronic physics, and this leads to the conclusion that the fermion propagator vanishes when p μ = 0. I also briefly explore a connection between this model and the two-channel, single-impurity Kondo effect. This paper may serve as an introduction to topological superconductors for high energy theorists, and perhaps as a taste of elementary particle physics for condensed matter theorists.
Chiral fermion dynamics in 2d magnetic vortices: Manifestation of momentum-spin-locking
NASA Astrophysics Data System (ADS)
Pötz, W.; Hammer, René
2016-11-01
The electronic surface-states of a topological insulator in the presence of an in-plane magnetization vortex M (ϕ)=M (cos(Φ+νϕ), sin(Φ+νϕ)) are investigated theoretically. For a general angle of magnetization Φ∈[0 ,2 π) and topological charge ν = 1, the modifications to the zero-mass single Dirac cone dispersion are treated exactly and the spectrum of bound eigenstates which forms in the energy window ±M cos(Φ) is derived. The space-time resolved dynamics of Dirac fermions in the presence of such vortices is studied numerically using a single-cone (2 + 1)D finite-difference scheme. In the continuous spectral region, Φ-dependent scattering of Dirac fermions at the vortex is observed. Depending on the type of vortex ( Φ, ν) and the impact parameter, the propagation direction of the Dirac fermion is changed: the magnetization of the vortex exerts a torque onto the fermion spin which, by momentum-spin locking associated with the helical Dirac states, results in an in-plane rotation of the propagation direction of the scattered Dirac fermion. In head-on collisions of a Gaussian wave-packet with ν = 1 vortices a Φ-dependent lensing effect is seen in our simulations. Depending on the direction of incidence, the vortex Φ=-π/2 , ν = 2 is identified as a coherent particle-beam splitter or "condenser" in head-on collisions.
Connecting Fermion Masses and Mixings to BSM Physics - Leptons
NASA Astrophysics Data System (ADS)
Stephenson, Gerard J., Jr.; Goldman, Terrence
2015-10-01
The universality of the Weak Interaction suggests that the structure of the Dirac mass matrix for neutrinos should be the same as that for the charged fermions. Thus, it must be true that there are at least three Majorana fermions, not necessarily mass eigenstates, which are sterile under the weak and electromagnetic interactions, and that three of these couple to the Higgs. We show that specific models of the sterile Majorana mass matrix exist for which the resulting effective active neutrino Majorana mass matrix is nearly diagonal in the current basis, with small but finite masses. Combined with the structure of the mass matrix for the charged leptons, this leads to a PMNS matrix for the lepton mixing that is nearly, but not exactly, tri-bi-maximal. Alt email:gjs@phys.unm.edu
Fermion Masses from Six Dimensions and Implications for Majorana Neutrinos
NASA Astrophysics Data System (ADS)
Frère, J.-M.; Libanov, M.; Mollet, S.; Troitsky, S.
2015-06-01
In these notes, we review the main results of our approach to fermion masses. The marge mass ratios between fermions, confronted with a unique breaking mechanism leading to vector bosons masses, led us to consider the possibility that they result from the overlap of fermion wave functions. Such overlaps vary indeed very strongly if the observed fermion families in 4 dimensions originate in a single family in 6 dimensions, through localized wave functions. This framework leads in a natural way to large mass ratios and small mixing angles between quarks. What came as a surprise is that if we impose that neutrinos behave as 2- component (“Majorana”) particles in 4D, a completely different situation is obtained for them. Instead of diagonal mass matrices, anti-diagonal ones emerge and lead to a generic prediction of combined inverted hierarchy, large mixing angles in the leptonicsector, and a suppression of neutrinoless-double beta decay placing it at the lower limit of the inverted hierarchy branch, a challenging situation for on-going and planned experiments. Our approach predicted the size of the θ13 mixing angle before its actual measurement. Possible signals at colliders are only briefly evoked.
Hadron spectrum, quark masses, and decay constants from light overlap fermions on large lattices
Galletly, D.; Horsley, R.; Guertler, M.; Perlt, H.; Schiller, A.; Rakow, P. E. L.; Schierholz, G.; Streuer, T.
2007-04-01
We present results from a simulation of quenched overlap fermions with Luescher-Weisz gauge field action on lattices up to 24{sup 3}48 and for pion masses down to {approx_equal}250 MeV. Among the quantities we study are the pion, rho, and nucleon masses; the light and strange quark masses; and the pion decay constant. The renormalization of the scalar and axial vector currents is done nonperturbatively in the RI-MOM scheme. The simulations are performed at two different lattice spacings, a{approx_equal}0.1 fm and {approx_equal}0.15 fm, and on two different physical volumes, to test the scaling properties of our action and to study finite volume effects. We compare our results with the predictions of chiral perturbation theory and compute several of its low-energy constants. The pion mass is computed in sectors of fixed topology as well.
Hadron Masses From Novel Fat-Link Fermion Actions
J. M. Zanotti; S. Bilson-Thompson; F. D. R. Bonnet; P. D. Coddington; D. B. Leinweber; A. G. Williams; J. B. Zhang; W. Melnitchouk; F. X. Lee
2001-11-01
The hadron mass spectrum is calculated in lattice QCD using a novel fat-link clover fermion action in which only the irrelevant operators in the fermion action are constructed using smeared links. The simulations are performed on a 16{sup 3} x 32 lattice with a lattice spacing of a=0.125 fm. We compare actions with n=4 and 12 smearing sweeps with a smearing fraction of 0.7. The n=4 Fat-Link Irrelevant Clover (FLIC) action provides scaling which is superior to mean-field improvement, and offers advantages over nonperturbative 0(a) improvement, including a reduced exceptional configuration problem.
Dynamics of Brans-Dicke cosmology with varying mass fermions
Liu Daojun
2010-09-15
In this paper, the cosmological dynamics of Brans-Dicke (BD) theory in which there are fermions with a coupling to BD scalar field as well as a self-interaction potential is investigated. The conditions that there exists a solution which is stable and represents a late-time accelerated expansion of the Universe are found. The variable mass of fermions cannot vanish exactly during the evolution of the Universe once it exists initially. It is shown that the late-time acceleration depends completely on the self-interaction of the fermion field if our investigation is restricted to the theory with positive BD parameter {omega}. Provided a negative {omega} is allowed, there will be another two classes of stable solutions describing the late-time accelerated expansion of the Universe.
A Three Higgs Doublet Model for Fermion Masses
NASA Astrophysics Data System (ADS)
Chao, Wei
2016-09-01
In this paper we propose a possible explanation to the Fermion mass hierarchy problem by fitting the type-II seesaw mechanism into the Higgs doublet sector, such that their vacuum expectation values are hierarchal. We extend the Standard Model with two extra Higgs doublets as well as a spontaneously broken UX (1) gauge symmetry. All the fermion Yukawa couplings except that of the top quark are of O}(10-2) in our model. Constraints on the parameter space of the model from low energy processes are studied. Besides, the lightest one of the neutral fermion fields, which is introduced to cancel the anomalies of the U(1)X gauge symmetry can be the cold dark matter candidate. We investigate its signature in the dark matter direct detection. Supported in part by the Wisconsin Alumni Research Foundation
Pseudoscalar condensation induced by chiral anomaly and vorticity for massive fermions
NASA Astrophysics Data System (ADS)
Fang, Ren-hong; Pang, Jin-yi; Wang, Qun; Wang, Xin-nian
2017-01-01
We derive the pseudoscalar condensate induced by anomaly and vorticity from the Wigner function for massive fermions in homogeneous electromagnetic fields. It has an anomaly term and a force-vorticity coupling term. As a mass effect, the pseudoscalar condensate is linearly proportional to the fermion mass in small mass expansion. By a generalization to two-flavor and three-flavor cases, the neutral pion and eta meson condensates are calculated from the Wigner function and have anomaly parts as well as force-vorticity parts, in which the anomaly part of the neutral pion condensate is consistent with the previous result. We also discuss the possible observables of the condensates in heavy-ion collisions such as collective flows of neutral pions and eta mesons which may be influenced by the electromagnetic field and vorticity profiles.
Artificial gauge fields and chiral edge states for ultracold fermions in synthetic dimensions
NASA Astrophysics Data System (ADS)
Fallani, Leonardo
2015-05-01
I will report on very recent experiments performed at LENS with ultracold 173Yb Fermi gases in artificial gauge fields. We have engineered Raman transitions between different 173Yb nuclear spin states to synthesize an effective lattice dynamics in a finite-sized ``extra dimension,'' which is encoded in the internal degree of freedom of the atoms. By using this innovative approach, we have realized synthetic magnetic fields for effectively-charged fermions in ladder geometries with a variable number of legs. Direct imaging of the individual legs allowed us to demonstrate the emergence of chiral edge currents and to observe edge-cyclotron orbits propagating along the edges of the system, thus providing a direct evidence of a fundamental feature of quantum Hall physics in condensed-matter systems.
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.
Mass-imbalanced fermionic mixture in a harmonic trap
NASA Astrophysics Data System (ADS)
Bazak, B.
2017-08-01
The mass-imbalanced fermionic mixture is studied, where N ≤5 identical fermions interact resonantly with an impurity, a distinguishable atom. The shell structure is explored, and the physics of a dynamic light-impurity is shown to be different from that of the static heavy-impurity case. The energies in a harmonic trap at unitarity are calculated and extrapolated to the zero-range limit. In doing so, the scale factor of the ground state, as well as of a few excited states, is calculated. In the 2 ≤N ≤4 systems, pure (N +1 ) Efimov states exist for large enough mass ratio. However, no sign for a six-body Efimov state in the (5 +1 ) system is found in the mass ratio explored, M /m ≤12 .
Fermion masses, flavour mixing and CP violation
Ross, G. G.
2008-11-23
The pattern of neutrino masses and mixings is characteristically different from those observed in the quark sector. I discuss how this can be elegantly explaned through a combination of an underlying family symmetry and the see-saw mechanism.
Localization properties of random-mass Dirac fermions from real-space renormalization group.
Mkhitaryan, V V; Raikh, M E
2011-06-24
Localization properties of random-mass Dirac fermions for a realization of mass disorder, commonly referred to as the Cho-Fisher model, are studied on the D-class chiral network. We show that a simple renormalization group (RG) description captures accurately a rich phase diagram: thermal metal and two insulators with quantized σ(xy), as well as transitions (including critical exponents) between them. Our main finding is that, even with small transmission of nodes, the RG block exhibits a sizable portion of perfect resonances. Delocalization occurs by proliferation of these resonances to larger scales. Evolution of the thermal conductance distribution towards a metallic fixed point is synchronized with evolution of signs of transmission coefficients, so that delocalization is accompanied with sign percolation.
Fermion masses as mixing parameters in the SM
NASA Astrophysics Data System (ADS)
Saldaña-Salazar, U. J.
2016-10-01
Flavor transitions via the charged current interactions are parametrized by a three dimensional and unitary transformation. This so called mixing matrix requires of four mixing parameters. Here we show that under the phenomenological observation of hierarchical fermion masses, m 3≫ m 2 ≫m1, a mixing parametrization can be built with its mixing parameters being the corresponding four independent mass ratios of each fermion sector, i.e., mu/mc, mc/mt, md/ms , and ms/mb and me/mM, mM/mT, m v1/m v2, and m v2/m v3, for the quark and lepton sector, respectively.
Texture of fermion mass matrices in partially unified theories
Dutta, B. |; Nandi, S. |
1996-12-31
We investigate the texture of fermion mass matrices in theories with partial unification (for example, SU(2){sub L} {times} SU(2){sub R} {times} SU(4){sub c}) at a scale of {approximately} 10{sup 12} GeV. Starting with the low energy values of the masses and the mixing angles, we find only two viable textures with at most four texture zeros. One of these corresponds to a somewhat modified Fritzsch textures. A theoretical derivation of these textures leads to new interesting relations among the masses and the mixing angles. 13 refs.
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.
Renormalization functions for Nf=2 and Nf=4 twisted mass fermions
NASA Astrophysics Data System (ADS)
Alexandrou, Constantia; Constantinou, Martha; Panagopoulos, Haralambos
2017-02-01
We present results on the renormalization functions of the quark field and fermion bilinears with up to one covariant derivative. For the fermion part of the action, we employ the twisted mass formulation with Nf=2 and Nf=4 degenerate dynamical quarks, while in the gluon sector, we use the Iwasaki-improved action. The simulations for Nf=4 have been performed for pion masses in the range of 390-760 MeV and at three values of the lattice spacing, a , corresponding to β =1.90 , 1.95, 2.10. The Nf=2 action includes a clover term with csw=1.57551 at β =2.10 , and three ensembles at different values of mπ. The evaluation of the renormalization functions is carried out in the RI' scheme using a momentum source. The nonperturbative evaluation is complemented with a perturbative computation, which is carried out at one-loop level and to all orders in the lattice spacing, a . For each renormalization function computed nonperturbatively, we subtract the corresponding lattice artifacts to all orders in a , so that a large part of the cutoff effects is eliminated. The renormalization functions are converted to the MS ¯ scheme at a reference energy scale of μ =2 GeV after taking the chiral limit.
Atom-dimer scattering length for fermions with different masses: Analytical study of limiting cases
Alzetto, F.; Leyronas, X.; Combescot, R.
2010-12-15
We consider the problem of obtaining the scattering length for a fermion colliding with a dimer, formed from a fermion identical to the incident one and another different fermion. This is done in the universal regime where the range of interactions is short enough that the scattering length a for nonidentical fermions is the only relevant quantity. This is the generalization to fermions with different masses of the problem solved long ago by Skorniakov and Ter-Martirosian for particles with equal masses. We solve this problem analytically in the two limiting cases where the mass of the solitary fermion is very large or very small compared to the mass of the two other identical fermions. This is done for both the value of the scattering length and the function entering the Skorniakov-Ter-Martirosian integral equation, for which simple explicit expressions are obtained.
Creating the fermion mass hierarchies with multiple Higgs bosons
NASA Astrophysics Data System (ADS)
Bauer, Martin; Carena, Marcela; Gemmler, Katrin
2016-12-01
After the Higgs boson discovery, it was established that the Higgs mechanism explains electroweak symmetry breaking and generates the masses of all particles in the Standard Model, with the possible exception of neutrino masses. The hierarchies among fermion masses and mixing angles, however, remain unexplained. We propose a new class of two Higgs doublet models in which a flavor symmetry broken at the electroweak scale addresses this problem. The models are strongly constrained by electroweak precision tests and the fact that they produce modifications to Higgs couplings and flavor-changing neutral currents; they are also constrained by collider searches for extra scalar bosons. The surviving models are very predictive, implying unavoidable new physics signals at the CERN Large Hadron Collider, e.g., extra Higgs bosons with masses M <700 GeV .
Creating the fermion mass hierarchies with multiple Higgs bosons
Bauer, Martin; Carena, Marcela; Gemmler, Katrin
2016-12-28
After the Higgs boson discovery, it is established that the Higgs mechanism explains electroweak symmetry breaking and generates the masses of all particles in the Standard Model, with the possible exception of neutrino masses. The hierarchies among fermion masses and mixing angles remain however unexplained. We propose a new class of two Higgs doublet models in which a flavor symmetry broken at the electroweak scale addresses this problem. The models are strongly constrained by electroweak precision tests and the fact that they produce modifications to Higgs couplings and flavor changing neutral currents; they are also constrained by collider searches for extra scalar bosons. The surviving models are very predictive, implying unavoidable new physics signals at the CERN Large Hadron Collider, e.g. extra Higgs Bosons with masses $M < 700$ GeV.
The chiral anomaly and thermopower of Weyl fermions in the half-Heusler GdPtBi.
Hirschberger, Max; Kushwaha, Satya; Wang, Zhijun; Gibson, Quinn; Liang, Sihang; Belvin, Carina A; Bernevig, B A; Cava, R J; Ong, N P
2016-11-01
The Dirac and Weyl semimetals are unusual materials in which the nodes of the bulk states are protected against gap formation by crystalline symmetry. The chiral anomaly, predicted to occur in both systems, was recently observed as a negative longitudinal magnetoresistance (LMR) in Na3Bi (ref. ) and in TaAs (ref. ). An important issue is whether Weyl physics appears in a broader class of materials. We report evidence for the chiral anomaly in the half-Heusler GdPtBi. In zero field, GdPtBi is a zero-gap semiconductor with quadratic bands. In a magnetic field, the Zeeman energy leads to Weyl nodes. We have observed a large negative LMR with the field-steering properties specific to the chiral anomaly. The chiral anomaly also induces strong suppression of the thermopower. We report a detailed study of the thermoelectric response function αxx of Weyl fermions. The scheme of creating Weyl nodes from quadratic bands suggests that the chiral anomaly may be observable in a broad class of semimetals.
The chiral anomaly and thermopower of Weyl fermions in the half-Heusler GdPtBi
NASA Astrophysics Data System (ADS)
Hirschberger, Max; Kushwaha, Satya; Wang, Zhijun; Gibson, Quinn; Liang, Sihang; Belvin, Carina A.; Bernevig, B. A.; Cava, R. J.; Ong, N. P.
2016-11-01
The Dirac and Weyl semimetals are unusual materials in which the nodes of the bulk states are protected against gap formation by crystalline symmetry. The chiral anomaly, predicted to occur in both systems, was recently observed as a negative longitudinal magnetoresistance (LMR) in Na3Bi (ref. ) and in TaAs (ref. ). An important issue is whether Weyl physics appears in a broader class of materials. We report evidence for the chiral anomaly in the half-Heusler GdPtBi. In zero field, GdPtBi is a zero-gap semiconductor with quadratic bands. In a magnetic field, the Zeeman energy leads to Weyl nodes. We have observed a large negative LMR with the field-steering properties specific to the chiral anomaly. The chiral anomaly also induces strong suppression of the thermopower. We report a detailed study of the thermoelectric response function αxx of Weyl fermions. The scheme of creating Weyl nodes from quadratic bands suggests that the chiral anomaly may be observable in a broad class of semimetals.
Radiative seesaw-type mechanism of fermion masses and non-trivial quark mixing
NASA Astrophysics Data System (ADS)
Arbeláez, Carolina; Hernández, A. E. Cárcamo; Kovalenko, Sergey; Schmidt, Ivan
2017-06-01
We propose a predictive inert two-Higgs doublet model, where the standard model (SM) symmetry is extended by S3⊗ Z2⊗ Z_{12} and the field content is enlarged by extra scalar fields, charged exotic fermions and two heavy right-handed Majorana neutrinos. The charged exotic fermions generate a non-trivial quark mixing and provide one-loop-level masses for the first- and second-generation charged fermions. The masses of the light active neutrinos are generated from a one-loop-level radiative seesaw mechanism. Our model successfully explains the observed SM fermion mass and mixing pattern.
NASA Astrophysics Data System (ADS)
Garron, Nicolas; Hudspith, Renwick J.; Lytle, Andrew T.
2016-11-01
We compute the hadronic matrix elements of the four-quark operators relevant for {K}^0-{overline{K}}^0 mixing beyond the Standard Model. Our results are from lattice QCD simulations with n f = 2 + 1 flavours of domain-wall fermion, which exhibit continuum-like chiral-flavour symmetry. The simulations are performed at two different values of the lattice spacing ( a ˜ 0 .08 and a ˜ 0 .11 fm) and with lightest unitary pion mass ˜ 300 MeV. For the first time, the full set of relevant four-quark operators is renormalised non-perturbatively through RI-SMOM schemes; a detailed description of the renormalisation procedure is presented in a companion paper. We argue that the intermediate renormalisation scheme is responsible for the discrepancies found by different collaborations. We also study different normalisations and determine the matrix elements of the relevant four-quark operators with a precision of ˜ 5% or better.
Fermion masses in the economical 3-3-1 model
Dong, P. V.; Huong, Tr. T.; Huong, D. T.; Long, H. N.
2006-09-01
We show that, in frameworks of the economical 3-3-1 model, all fermions get masses. At the tree level, one up-quark and two down-quarks are massless, but the one-loop corrections give all quarks the consistent masses. This conclusion is in contradiction to the previous analysis in which the third scalar triplet has been introduced. This result is based on the key properties of the model: First, there are three quite different scales of vacuum expectation values: {omega}{approx}O(1) TeV, v{approx_equal}246 GeV, and u{approx}O(1) GeV. Second, there exist two types of Yukawa couplings with different strengths: the lepton-number conserving couplings h's and the lepton-number violating ones s's satisfying the condition in which the second are much smaller than the first ones: s<
Effective Mass and g Factor of Four-Flux-Quanta Composite Fermions
Yeh, A.S.; Tsui, D.C.; Stormer, H.L.; Pfeiffer, L.N.; Baldwin, K.W.; West, K.W.; Stormer, H.L.; Tsui, D.C.
1999-01-01
We investigate the properties of composite fermions with four attached flux quanta through tilted-field experiments near Landau level filling factor {nu}=3/4 . The observed collapse of fractional quantum Hall gaps in the vicinity of this quarter-filling state can be comprehensively understood in terms of composite fermions with mass and spin. Remarkably, the effective mass and g factor of these four-flux-quanta composite fermions around {nu}=3/4 are very similar to those of two-flux-quanta composite fermions around {nu}=3/2 . {copyright} {ital 1999} {ital The American Physical Society }
Flavor dependence of quasi Nambu-Goldstone fermion masses
NASA Astrophysics Data System (ADS)
Yasuè, Masaki; Terazawa, Hidezumi
1987-10-01
A possible flavor dependence of masses for light quasi Nambu-Goldstone fermions (QNGF's) is examined in a supersymmetric (SUSY) nonlinear-interaction model of the Nambu-Jona-Lasinio type with SO(2N, C)-->SO(n, C)×SO(2N-n, C) by
CHIRAL LIMIT AND LIGHT QUARK MASSES IN 2+1 FLAVOR DOMAIN WALL QCD.
SCHOLZ,E.; LIN, M.
2007-07-30
We present results for meson masses and decay constants measured on 24{sup 3} x 64 lattices using the domain wall fermion formulation with an extension of the fifth dimension of L{sub s} = 16 for N{sub f} 2 + 1 dynamical quark flavors. The lightest dynamical meson mass in our set-up is around 331MeV. while partially quenched mesons reach masses as low as 250MeV. The applicability of SU(3) x SU(3) and SU(2) x SU(2) (partially quenched) chiral perturbation theory will be compared and we quote values for the low-energy constants from both approaches. We will extract the average light quark and strange quark masses and use a non-perturbative renormalization technique (RI/MOM) to quote their physical values. The pion and kaon decay constants are determined at those values from our chiral fits and their ratio is used to obtain the CKM-matrix element |V{sub us}|. The results presented here include statistical errors only.
BCS-BEC crossover with unequal-mass fermions
Diener, Roberto B.; Randeria, Mohit
2010-03-15
We investigate the crossover from BCS pairing to molecular Bose-Einstein condensation (BEC) in an atomic gas with two fermion species with masses m{sub {up_arrow}{ne}m{down_arrow}}tuned through a Feshbach resonance. We present results for the T=0 equation of state as a function of the scattering length including the effects of Gaussian fluctuations about the mean field ground state. We compute the ground state energy as a function of m{sub {up_arrow}/}m{sub {down_arrow}}at unitarity and find excellent agreement with the quantum Monte Carlo result for m{sub {up_arrow}/}m{sub {down_arrow}=}6.67 for a {sup 40}K-{sup 6}Li mixture. We show that the dimer scattering length in the BEC limit as a function of m{sub {up_arrow}/}m{sub {down_arrow}}compares well with the exact four-body results of Petrov et al. [J. Phys. B 38, S645 (2005)]. We also derive the condition for trapping frequencies to obtain an unpolarized gas in a harmonic trap.
Symmetries and unitary interactions of mass dimension one fermionic dark matter
NASA Astrophysics Data System (ADS)
Lee, Cheng-Yang
2016-12-01
The fermionic fields constructed from Elko have several unexpected properties. They satisfy the Klein-Gordon but not the Dirac equation and are of mass dimension one instead of three-half. Starting with the Klein-Gordon Lagrangian, we initiate a careful study of the symmetries and interactions of these fermions and their higher-spin generalizations. We find, although the fermions are of mass dimension one, the four-point fermionic self-interaction violates unitarity at high-energy so it cannot be a fundamental interaction of the theory. Using the optical theorem, we derive an explicit bound on energy for the fermion-scalar interaction. It follows that for the spin-half fermions, the demand of renormalizability and unitarity forbids four-point interactions and only allows for the Yukawa interaction. For fermions with spin j > 1 2, they have no renormalizable or unitary interactions. Since the theory is described by a Klein-Gordon Lagrangian, the interaction generated by the local U(1) gauge symmetry which contains a four-point interaction, is excluded by the demand of renormalizability. In the context of the Standard Model, these properties make the spin-half fermions natural dark matter candidates. Finally, we discuss the recent developments on the introduction of new adjoint and spinor duals which may allow us to circumvent the unitarity constraints on the interactions.
Quantum critical point of Dirac fermion mass generation without spontaneous symmetry breaking
NASA Astrophysics Data System (ADS)
He, Yuan-Yao; Wu, Han-Qing; You, Yi-Zhuang; Xu, Cenke; Meng, Zi Yang; Lu, Zhong-Yi
2016-12-01
We study a lattice model of interacting Dirac fermions in (2 +1 ) dimensions space-time with an SU(4) symmetry. While increasing the interaction strength, this model undergoes a continuous quantum phase transition from a weakly interacting Dirac semimetal to a fully gapped and nondegenerate phase without condensing any Dirac fermion bilinear mass operator. This unusual mechanism for mass generation is consistent with recent studies of interacting topological insulators/superconductors, and also consistent with recent progress in the lattice QCD community.
Ambiguities and subtleties in fermion mass terms in practical quantum field theory
Cheng, Yifan Kong, Otto C.W.
2014-09-15
This is a review on structure of the fermion mass terms in quantum field theory, under the perspective of its practical applications in the real physics of Nature—specifically, we discuss fermion mass structure in the Standard Model of high energy physics, which successfully describes fundamental physics up to the TeV scale. The review is meant to be pedagogical, with detailed mathematics presented beyond the level one can find any easily in the textbooks. The discussions, however, bring up important subtleties and ambiguities about the subject that may be less than well appreciated. In fact, the naive perspective of the nature and masses of fermions as one would easily drawn from the presentations of fermion fields and their equations of motion from a typical textbook on quantum field theory leads to some confusing or even wrong statements which we clarify here. In particular, we illustrate clearly that a Dirac fermion mass eigenstate is mathematically equivalent to two degenerated Majorana fermion mass eigenstates at least as long as the mass terms are concerned. There are further ambiguities and subtleties in the exact description of the eigenstate(s). Especially, for the case of neutrinos, the use of the Dirac or Majorana terminology may be mostly a matter of choice. The common usage of such terminology is rather based on the broken SU(2) charges of the related Weyl spinors hence conventional and may not be unambiguously extended to cover more complicate models. - Highlights: • Structure of fermion mass terms in practical quantum field theory is reviewed. • Important subtleties and ambiguities on the subject are clarified. • A mass eigenstate Dirac fermion and two degenerated Majorana ones are equivalent. • The conventional meaning of such terminology for neutrinos is critically discussed.
Ambiguities and subtleties in fermion mass terms in practical quantum field theory
NASA Astrophysics Data System (ADS)
Cheng, Yifan; Kong, Otto C. W.
2014-09-01
This is a review on structure of the fermion mass terms in quantum field theory, under the perspective of its practical applications in the real physics of Nature-specifically, we discuss fermion mass structure in the Standard Model of high energy physics, which successfully describes fundamental physics up to the TeV scale. The review is meant to be pedagogical, with detailed mathematics presented beyond the level one can find any easily in the textbooks. The discussions, however, bring up important subtleties and ambiguities about the subject that may be less than well appreciated. In fact, the naive perspective of the nature and masses of fermions as one would easily drawn from the presentations of fermion fields and their equations of motion from a typical textbook on quantum field theory leads to some confusing or even wrong statements which we clarify here. In particular, we illustrate clearly that a Dirac fermion mass eigenstate is mathematically equivalent to two degenerated Majorana fermion mass eigenstates at least as long as the mass terms are concerned. There are further ambiguities and subtleties in the exact description of the eigenstate(s). Especially, for the case of neutrinos, the use of the Dirac or Majorana terminology may be mostly a matter of choice. The common usage of such terminology is rather based on the broken SU(2) charges of the related Weyl spinors hence conventional and may not be unambiguously extended to cover more complicate models.
Fermion mass hierarchy and nonhierarchical mass ratios in SU(5)xU(1){sub F}
Duque, Luis F.; Gutierrez, Diego A.; Nardi, Enrico; Norena, Jorge
2008-08-01
We consider a SU(5)xU(1){sub F} grand unified theory (GUT)-flavor model in which the number of effects that determine the charged fermions Yukawa matrices is much larger than the number of observables, resulting in a hierarchical fermion spectrum with no particular regularities. The GUT-flavor symmetry is broken by flavons in the adjoint of SU(5), realizing a variant of the Froggatt-Nielsen mechanism that gives rise to a large number of effective operators. By assuming a common mass for the heavy fields and universality of the fundamental Yukawa couplings, we reduce the number of free parameters to one. The observed fermion mass spectrum is reproduced thanks to selection rules that discriminate among various contributions. Bottom-tau Yukawa unification is preserved at leading order, but there is no unification for the first two families. Interestingly, U(1){sub F} charges alone do not determine the hierarchy, and can only give upper bounds on the parametric suppression of the Yukawa operators.
Could fermion masses play a role in the stabilization of the dilaton in cosmology?
NASA Astrophysics Data System (ADS)
Cabo, Alejandro; Brandenberger, Robert
2009-02-01
We study the possibility that the Dilaton is stabilized by the contribution of fermion masses to its effective potential. We consider the Dilaton gravity action in four dimensions to which we add a mass term for a Dirac fermion. Such an action describes the interaction of the Dilaton with the fermions in the Yang-Mills sector of the coupled supergravity/super-Yang-Mills action which emerges as the low energy effective action of superstring theory after the extra spatial dimensions have been fixed. The Dilaton couples to the Fermion mass term via the usual exponential factor of this field which multiplies the non-kinetic terms of the matter Lagrangian, if we work in the Einstein frame. In the kinetic part of the Fermion action in the Einstein frame the Dilaton does not enter. Such masses can be generated in several ways: they can arise as a consequence of flux about internal spatial dimensions, they may arise as thermal fermion masses in a quasi-static phase in the early universe, and they will arise after the breaking of supersymmetry at late times. The vacuum contribution to the potential for the Dilaton is evaluated up to two loops. The result shows a minimum which could stabilize the Dilaton for reasonable ranges of parameter values.
Could fermion masses play a role in the stabilization of the dilaton in cosmology?
Cabo, Alejandro; Brandenberger, Robert E-mail: rhb@hep.physics.mcgill.ca
2009-02-15
We study the possibility that the Dilaton is stabilized by the contribution of fermion masses to its effective potential. We consider the Dilaton gravity action in four dimensions to which we add a mass term for a Dirac fermion. Such an action describes the interaction of the Dilaton with the fermions in the Yang-Mills sector of the coupled supergravity/super-Yang-Mills action which emerges as the low energy effective action of superstring theory after the extra spatial dimensions have been fixed. The Dilaton couples to the Fermion mass term via the usual exponential factor of this field which multiplies the non-kinetic terms of the matter Lagrangian, if we work in the Einstein frame. In the kinetic part of the Fermion action in the Einstein frame the Dilaton does not enter. Such masses can be generated in several ways: they can arise as a consequence of flux about internal spatial dimensions, they may arise as thermal fermion masses in a quasi-static phase in the early universe, and they will arise after the breaking of supersymmetry at late times. The vacuum contribution to the potential for the Dilaton is evaluated up to two loops. The result shows a minimum which could stabilize the Dilaton for reasonable ranges of parameter values.
Quark mass correction to chiral separation effect and pseudoscalar condensate
NASA Astrophysics Data System (ADS)
Guo, Er-dong; Lin, Shu
2017-01-01
We derived an analytic structure of the quark mass correction to chiral separation effect (CSE) in small mass regime. We confirmed this structure by a D3/D7 holographic model study in a finite density, finite magnetic field background. The quark mass correction to CSE can be related to correlators of pseudo-scalar condensate, quark number density and quark condensate in static limit. We found scaling relations of these correlators with spatial momentum in the small momentum regime. They characterize medium responses to electric field, inhomogeneous quark mass and chiral shift. Beyond the small momentum regime, we found existence of normalizable mode, which possibly leads to formation of spiral phase. The normalizable mode exists beyond a critical magnetic field, whose magnitude decreases with quark chemical potential.
Analysis of chirality by femtosecond laser ionization mass spectrometry.
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.
Quark masses, chiral symmetry, and the U(1) anomaly
Creutz, M.
1996-09-17
The author discusses the mass parameters appearing in the gauge theory of the strong interactions, concentrating on the two flavor case. He shows how the effect of the CP violating parameter {theta} is simply interpreted in terms of the state of the aether via an effective potential for meson fields. For degenerate flavors he shows that a first order phase transition is expected at {theta} = {pi}. The author speculates on the implications of this structure for Wilson`s 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.
Origin of families of fermions and their mass matrices
Bracic, A. Borstnik; Borstnik, N. S. Mankoc
2006-10-01
,3)) weak chargeless quarks and leptons and the left handed weak charged quarks and leptons (with the right handed neutrino included). A part of the starting Lagrange density of a Weyl spinor in d=1+13 transforms right handed quarks and leptons into left handed quarks and leptons manifesting as the Yukawa couplings of the standard model. A kind of the Clifford algebra objects generates families of quarks and leptons and contributes to diagonal and off-diagonal Yukawa couplings. The approach predicts an even number of families, treating leptons and quarks equivalently (we do not study a possible appearance of Majorana fermions yet). In this paper we investigate within this approach the appearance of the Yukawa couplings within one family of quarks and leptons as well as among the families (without assuming any Higgs fields like in the standard model). We present the mass matrices for four families and investigate whether our way of generating families might explain the origin of families of quarks and leptons as well as their observed properties--the masses and the mixing matrices. Numerical results are presented in Ref. [M. Breskvar, D. Lukman, and N. S. Mankoc Borstnik, hep-ph/0606159.].
NASA Astrophysics Data System (ADS)
Alexandrou, C.; Kallidonis, C.
2017-08-01
The masses of the low-lying baryons are evaluated using an ensemble with two degenerate light twisted mass clover-improved quarks with mass tuned to reproduce the physical pion mass. The Iwasaki improved gluonic action is employed. The coupling constant value corresponds to a lattice spacing of a =0.0938 (3 )(2 ) fm , determined from the nucleon mass. We find that the clover term supresses isospin symmetry breaking as compared to our previous results using Nf=2 +1 +1 twisted mass fermions. The masses of the hyperons and charmed baryons evaluated using this ensemble are in agreement with the experimental values. We provide predictions for the mass of the doubly charmed Ξcc * , as well as of the doubly and triply charmed Ω s that have not yet been determined experimentally.
Adaptive aggregation-based domain decomposition multigrid for twisted mass fermions
NASA Astrophysics Data System (ADS)
Alexandrou, Constantia; Bacchio, Simone; Finkenrath, Jacob; Frommer, Andreas; Kahl, Karsten; Rottmann, Matthias
2016-12-01
The adaptive aggregation-base domain decomposition multigrid method [A. Frommer et al., SIAM J. Sci. Comput. 36, A1581 (2014)] is extended for two degenerate flavors of twisted mass fermions. By fine-tuning the parameters we achieve a speed-up of the order of a hundred times compared to the conjugate gradient algorithm for the physical value of the pion mass. A thorough analysis of the aggregation parameters is presented, which provides a novel insight into multigrid methods for lattice quantum chromodynamics independently of the fermion discretization.
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.
Negative-Parity Baryon Masses Using O(a)-improved Fermion Action
M. Gockeler; R. Horsley; D. Pleiter; P.E.L. Rakow; G. Schierholz; C.M. Maynard; D.G. Richards
2001-06-01
We present a calculation of the mass of the lowest-lying negative-parity J=1/2{sup {minus}} state in quenched QCD. Results are obtained using a non-perturbatively {Omicron}(a)-improved clover fermion action, and a splitting found between the masses of the nucleon, and its parity partner. The calculation is performed on two lattice volumes, and at three lattice spacings, enabling a study of both finite-volume and finite lattice-spacing uncertainties. A comparison is made with results obtained using the unimproved Wilson fermion action.
Origin of families of fermions and their mass matrices
NASA Astrophysics Data System (ADS)
Bračič, A. Borštnik; Borštnik, N. S. Mankoč
2006-10-01
one family appear in one Weyl representation of a chosen handedness of the Lorentz group, if analyzed with respect to the standard model gauge groups, which are subgroups of the group SO(1,13): the right handed (with respect to SO(1,3)) weak chargeless quarks and leptons and the left handed weak charged quarks and leptons (with the right handed neutrino included). A part of the starting Lagrange density of a Weyl spinor in d=1+13 transforms right handed quarks and leptons into left handed quarks and leptons manifesting as the Yukawa couplings of the standard model. A kind of the Clifford algebra objects generates families of quarks and leptons and contributes to diagonal and off-diagonal Yukawa couplings. The approach predicts an even number of families, treating leptons and quarks equivalently (we do not study a possible appearance of Majorana fermions yet). In this paper we investigate within this approach the appearance of the Yukawa couplings within one family of quarks and leptons as well as among the families (without assuming any Higgs fields like in the standard model). We present the mass matrices for four families and investigate whether our way of generating families might explain the origin of families of quarks and leptons as well as their observed properties—the masses and the mixing matrices. Numerical results are presented in Ref. [M. Breskvar, D. Lukman, and N. S. Mankoč Borštnik, hep-ph/0606159.].
Chiral recognition and determination of enantiomeric excess by mass spectrometry: A review.
Yu, Xiangying; Yao, Zhong-Ping
2017-05-22
Chiral analysis is of great importance to fundamental and applied research in chemical, biological and pharmaceutical sciences. Due to the superiority of mass spectrometry (MS) over other analytical methods in terms of speed, specificity and sensitivity, chiral analysis by MS has attracted much interest in recent years. Chiral analysis by MS typically involves introduction of a chiral selector to form diastereomers with analyte enantiomers, and comparison of the behaviors of diastereomers in MS. Chiral differentiation can be achieved by comparing the relative abundances of diastereomers, the thermodynamic or kinetic constants of ion-molecule reactions of diastereomers in the gas phase, the dissociation of diastereomers in MS/MS, or the mobility of diastereomers in ion mobility mass spectrometry. In this review, chiral recognition and determination of enantiomeric excess by these chiral MS methods were summarized, and the prospects of chiral analysis by MS were discussed.
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.
Finster, Felix E-mail: simone.murro@ur.de Murro, Simone E-mail: simone.murro@ur.de Röken, Christian E-mail: simone.murro@ur.de
2016-07-15
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.
Mixed Meson Mass for Domain-Wall Valence and Staggered Sea Fermions
Konstantinos Orginos; Andre Walker-Loud
2007-05-01
Mixed action lattice calculations allow for an additive lattice spacing dependent mass renormalization of mesons composed of one sea and one valence quark, regardless of the type of fermion discretization methods used in the valence and sea sectors. The value of the mass renormalization depends upon the lattice actions used. This mixed meson mass shift is the most important lattice artifact to determine for mixed action calculations: because it modifies the pion mass, it plays a central role in the low energy dynamics of all hadronic correlation functions. We determine the leading order and next to leading order additive mass renormalization of valence-sea mesons for a mixed lattice action with domain-wall valence fermions and staggered sea fermions. We find that on the asqtad improved coarse MILC lattices, the leading order additive mass renormalization for the mixed mesons is Δ(am)^2 LO = 0.0409(11) which corresponds to a^2 Δ_Mix = (319 MeV)^2± (53 MeV)^2 for a = 0.125 fm. We also find significant next to leading order contributions which reduce the mass renormalization by a significant amount, such that for 0 < am_π ≤ 0.22 the mixed meson mass renormalization is well approximated by Δ(am)^2 = 0.0340 (23) or a^2δ_Mix = (290 MeV)^2 ± (76 MeV)^2. The full next-to-leading order analysis is presented in the text.
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.
Quantum and thermal fluctuations in the BCS-BEC crossover with unequal mass fermions
NASA Astrophysics Data System (ADS)
Diener, Roberto; Zhou, Qi; Randeria, Mohit
2008-03-01
A lot of progress has been done in the study of the BCS-BEC crossover for equal-mass fermions in recent years by both theory and experimental groups. An extension of this problem which is starting to receive more attention is the study of mixtures of fermions with different masses, such as a mixture of ^40K and ^6Li. Using our functional integral method, which we have previously used to study the equal-mass case and which includes the effect of collective excitations (see R. B. Diener et al, cond-mat/0709.2653), we have studied the properties of a fermionic gas with unequal masses across the BCS-BEC crossover. We will present results for different thermodynamical quantities as a function of mass ratio and interaction strength: e.g. the beta parameter at unitarity, the ground state energy as a function of 1/(kFas), as well as the dimer scattering in the BEC limit as a function of mass ratio which agrees to within 20% with the exact four-body calculation of D. Petrov et al., J. Phys. B At. Mol. Opt. Phys. 38, S645 (2005).
Neutrinos and the origin of fermion mass structure
Ross, Graham G.
2007-11-20
The pattern of neutrino masses and mixings is characteristically different from those observed in the quark sector. I discuss why this should be the case and what implications this has for the origin of quark and lepton masses, mixings and CP violation.
Permutation symmetry and the origin of fermion mass hierarchy
Babu, K.S.; Mohapatra, R.N. )
1990-06-04
A realization of the flavor-democracy'' approach to quark and lepton masses is provided in the context of the standard model with a horizontal {ital S}{sub 3} permutation symmetry. In this model, {ital t} and {ital b} quarks pick up mass at the tree level, {ital c}, {ital s}-quark and {tau}-lepton masses arise at the one-loop level, {ital u}, {ital d}, and {mu} masses at the two-loop level, and the electron mass at the three-loop level, thus reproducing the observed hierarchial structure without fine tuning of the Yukawa couplings. The pattern of quark mixing angles also emerges naturally, with {ital V}{sub {ital u}{ital s}},{ital V}{sub {ital c}{ital b}}{approx}{ital O}({epsilon}), {ital V}{sub {ital u}{ital b}}{approx}{ital O}({epsilon}{sup 2}), where {epsilon} is a loop expansion parameter.
Connecting Fermion Masses and Mixings to BSM Physics - Quarks
NASA Astrophysics Data System (ADS)
Goldman, Terrence; Stephenson, Gerard J., Jr.
2015-10-01
The ``democratic'' mass matrix with BSM physics assumptions has been studied without success. We invert the process and use the ``democratic'' mass matrix plus a parametrization of all possible BSM corrections to analyze the implications of the observed masses and CKM weak interaction current mixing for the BSM parameter values for the up-quarks and down-quarks. We observe that the small mixing of the so-called ``third generation'' is directly related to the large mass gap from the two lighter generations. Conversely, the relatively large value of the Cabibbo angle arises because the mass matrices in the light sub-sector (block diagonalized from the full three channel problem) are neither diagonal nor degenerate and differ significantly between the up and down cases. Alt email:t.goldman@gmail.com
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.
Predictive Pati-Salam theory of fermion masses and mixing
NASA Astrophysics Data System (ADS)
Cárcamo Hernández, A. E.; Kovalenko, Sergey; Valle, José W. F.; Vaquera-Araujo, C. A.
2017-07-01
We propose a Pati-Salam extension of the standard model incorporating a flavor symmetry based on the Δ (27) group. The theory realizes a realistic Froggatt-Nielsen picture of quark mixing and a predictive pattern of neutrino oscillations. We find that, for normal neutrino mass ordering, the atmospheric angle must lie in the higher octant, CP must be violated in oscillations, and there is a lower bound for the 0ν ββ decay rate. For the case of inverted mass ordering, we find that the lower atmospheric octant is preferred, and that CP can be conserved in oscillations. Neutrino masses arise from a low-scale seesaw mechanism, whose messengers can be produced by a Z' portal at the LHC.
Switching of Dirac-Fermion Mass at the Interface of Ultrathin Ferromagnet and Rashba Metal.
Honma, K; Sato, T; Souma, S; Sugawara, K; Tanaka, Y; Takahashi, T
2015-12-31
We have performed spin- and angle-resolved photoemission spectroscopy on tungsten (110) interfaced with an ultrathin iron (Fe) layer to study an influence of ferromagnetism on the Dirac-cone-like surface-interface states. We found an unexpectedly large energy gap of 340 meV at the Dirac point, and have succeeded in switching the Dirac-fermion mass by controlling the direction of Fe spins (in plane or out of plane) through tuning the thickness of the Fe overlayer or adsorbing oxygen on it. Such a manipulation of Dirac-fermion mass via the magnetic proximity effect opens a promising platform for realizing new spintronic devices utilizing a combination of exchange and Rashba-spin-orbit interactions.
An explicit SU(12) family and flavor unification model with natural fermion masses and mixings
Albright, Carl H.; Feger, Robert P.; Kephart, Thomas W.
2012-07-01
We present an SU(12) unification model with three light chiral families, avoiding any external flavor symmetries. The hierarchy of quark and lepton masses and mixings is explained by higher dimensional Yukawa interactions involving Higgs bosons that contain SU(5) singlet fields with VEVs about 50 times smaller than the SU(12) unification scale. The presented model has been analyzed in detail and found to be in very good agreement with the observed quark and lepton masses and mixings.
Hernandez-Galeana, Albino
2007-11-01
I report the analysis performed on fermion masses and mixing, including neutrino mixing, within the context of a model with hierarchical radiative mass generation mechanism for light charged fermions, mediated by exotic scalar particles at one and two loops, respectively, meanwhile the neutrinos get Majorana mass terms at tree level through the Yukawa couplings with two SU(2){sub L} Higgs triplets. All the resulting mass matrices in the model, for the u, d, and e fermion charged sectors, the neutrinos and the exotic scalar particles, are diagonalized in exact analytical form. Quantitative analysis shows that this model is successful to accommodate the hierarchical spectrum of masses and mixing in the quark sector as well as the charged lepton masses. The lepton mixing matrix, V{sub PMNS}, is written completely in terms of the neutrino masses m{sub 1}, m{sub 2}, and m{sub 3}. Large lepton mixing for {theta}{sub 12} and {theta}{sub 23} is predicted in the range of values 0.7 < or approx. sin{sup 2}2{theta}{sub 12} < or approx. 0.7772 and 0.87 < or approx. sin{sup 2}2{theta}{sub 23} < or approx. 0.9023 by using 0.033 < or approx. s{sub 13}{sup 2} < or approx. 0.04. These values for lepton mixing are consistent with 3{sigma} allowed ranges provided by recent global analysis of neutrino data oscillation. From {delta}m{sub sol}{sup 2} bounds, neutrino masses are predicted in the range of values m{sub 1}{approx_equal}(1.706-2.494)x10{sup -3} eV, m{sub 2}{approx_equal}(6.675-12.56)x10{sup -3} eV, and m{sub 3}{approx_equal}(1.215-2.188)x10{sup -2} eV, respectively. The above allowed lepton mixing leads to the quark-lepton complementary relations {theta}{sub 12}{sup CKM}+{theta}{sub 12}{sup PMNS}{approx_equal}41.543 deg. -44.066 deg. and {theta}{sub 23}{sup CKM}+{theta}{sub 23}{sup PMNS}{approx_equal}36.835 deg. -38.295 deg. The new exotic scalar particles induce flavor changing neutral currents and contribute to lepton flavor violating processes such as E{yields}e{sub 1}e
NASA Astrophysics Data System (ADS)
Kutnink, Timothy; Santrach, Amelia; Hockett, Sarah; Barcus, Scott; Petridis, Athanasios
2016-09-01
The time-dependent electromagnetically self-coupled Dirac equation is solved numerically by means of the staggered-leap-frog algorithm with reflecting boundary conditions. The stability region of the method versus the interaction strength and the spatial-grid size over time-step ratio is established. The expectation values of several dynamic operators are then evaluated as functions of time. These include the fermion and electromagnetic energies and the fermion dynamic mass, as the self-interacting spinors are no longer mass-eigenfunctions. There is a characteristic, non-exponential, oscillatory dependence leading to asymptotic constants of these expectation values. In the case of the fermion mass this amounts to renormalization. The dependence of the expectation values on the spatial-grid size is evaluated in detail. Statistical regularization, employing a canonical ensemble whose temperature is the inverse of the grid size, is used to remove the grid-size dependence and produce a finite result in the continuum limit.
Fermion localization and resonances on two-field thick branes
NASA Astrophysics Data System (ADS)
Almeida, C. A. S.; Casana, R.; Ferreira, M. M., Jr.; Gomes, A. R.
2009-06-01
We consider (4, 1)-dimensional branes constructed with two scalar fields ϕ and χ coupled to a Dirac spinor field by means of a general Yukawa coupling. The equation of motion for the coefficients of the chiral decomposition of the spinor in curved spacetime leads to a Schrödinger-like equation whose solutions allow to obtain the masses of the fermionic modes. The simplest Yukawa coupling Ψ¯ϕχΨ is considered for the Bloch brane model and fermion localization is studied. We found resonances for both chiralities and related their appearance to branes with internal structure.
Fermion localization and resonances on two-field thick branes
Almeida, C. A. S.; Casana, R.; Ferreira, M. M. Jr.; Gomes, A. R.
2009-06-15
We consider (4, 1)-dimensional branes constructed with two scalar fields {phi} and {chi} coupled to a Dirac spinor field by means of a general Yukawa coupling. The equation of motion for the coefficients of the chiral decomposition of the spinor in curved spacetime leads to a Schroedinger-like equation whose solutions allow to obtain the masses of the fermionic modes. The simplest Yukawa coupling {psi}{phi}{chi}{psi} is considered for the Bloch brane model and fermion localization is studied. We found resonances for both chiralities and related their appearance to branes with internal structure.
Mass of heavy-light mesons in a constituent quark picture with partially restored chiral symmetry
NASA Astrophysics Data System (ADS)
Park, Aaron; Gubler, Philipp; Harada, Masayasu; Lee, Su Houng; Nonaka, Chiho; Park, Woosung
2016-03-01
We probe effects of the partial chiral symmetry restoration to the mass of heavy-light mesons in a constituent quark model by changing the constituent quark mass of the light quark. Due to the competing effect between the quark mass and the linearly rising potential, whose contribution to the energy increases as the quark mass decreases, the heavy-light meson mass has a minimum value near the constituent quark mass typically used in the vacuum. Hence, the meson mass increases as one decreases the constituent quark mass consistent with recent QCD sum rule analyses, which show an increasing D meson mass as the chiral order parameter decreases.
Hierarchy spectrum of SM fermions: from top quark to electron neutrino
NASA Astrophysics Data System (ADS)
Xue, She-Sheng
2016-11-01
In the SM gauge symmetries and fermion content of neutrinos, charged leptons and quarks, we study the effective four-fermion operators of Einstein-Cartan type and their contributions to the Schwinger-Dyson equations of fermion self-energy functions. The study is motivated by the speculation that these four-fermion operators are probably originated due to the quantum gravity, which provides the natural regularization for chiral-symmetric gauge field theories. In the chiral-gauge symmetry breaking phase, as to achieve the energetically favorable ground state, only the top-quark mass is generated via the spontaneous symmetry breaking, and other fermion masses are generated via the explicit symmetry breaking induced by the top-quark mass, four-fermion interactions and fermion-flavor mixing matrices. A phase transition from the symmetry breaking phase to the chiral-gauge symmetric phase at TeV scale occurs and the drastically fine-tuning problem can be resolved. In the infrared fixed-point domain of the four-fermion coupling for the SM at low energies, we qualitatively obtain the hierarchy patterns of the SM fermion Dirac masses, Yukawa couplings and family-flavor mixing matrices with three additional right-handed neutrinos ν R f . Large Majorana masses and lepton-number symmetry breaking are originated by the four-fermion interactions among ν R f and their left-handed conjugated fields ν R fc . Light masses of gauged Majorana neutrinos in the normal hierarchy (10-5 - 10-2 eV) are obtained consistently with neutrino oscillations. We present some discussions on the composite Higgs phenomenology and forward-backward asymmetry of toverline{t} -production, as well as remarks on the candidates of light and heavy dark matter particles (fermions, scalar and pseudoscalar bosons).
Nucleon axial form factors using Nf=2 twisted mass fermions with a physical value of the pion mass
NASA Astrophysics Data System (ADS)
Alexandrou, C.; Constantinou, M.; Hadjiyiannakou, K.; Jansen, K.; Kallidonis, C.; Koutsou, G.; Vaquero Aviles-Casco, A.
2017-09-01
We present results on the nucleon axial and induced pseudoscalar form factors using an ensemble of two degenerate twisted mass clover-improved fermions with mass yielding a pion mass of mπ=130 MeV . We evaluate the isovector and the isoscalar, as well as the strange and the charm axial form factors. The disconnected contributions are evaluated using recently developed methods that include deflation of the lower eigenstates, allowing us to extract the isoscalar, strange, and charm axial form factors. We find that the disconnected quark loop contributions are nonzero and particularly large for the induced pseudoscalar form factor.
Two-dimensional thermofield bosonization II: Massive fermions
Amaral, R.L.P.G.
2008-11-15
We consider the perturbative computation of the N-point function of chiral densities of massive free fermions at finite temperature within the thermofield dynamics approach. The infinite series in the mass parameter for the N-point functions are computed in the fermionic formulation and compared with the corresponding perturbative series in the interaction parameter in the bosonized thermofield formulation. Thereby we establish in thermofield dynamics the formal equivalence of the massive free fermion theory with the sine-Gordon thermofield model for a particular value of the sine-Gordon parameter. We extend the thermofield bosonization to include the massive Thirring model.
Nonlinear realization of chiral symmetry on the lattice
NASA Astrophysics Data System (ADS)
Chandrasekharan, Shailesh; Pepe, Michele; Steffen, Frank Daniel; Wiese, Uwe-Jens
2003-12-01
We formulate lattice theories in which chiral symmetry is realized nonlinearly on the fermion fields. In this framework the fermion mass term does not break chiral symmetry. This property allows us to use the Wilson term to remove the doubler fermions while maintaining exact chiral symmetry on the lattice. Our lattice formulation enables us to address non-perturbative questions in effective field theories of baryons interacting with pions and in models involving constituent quarks interacting with pions and gluons. We show that a system containing a non-zero density of static baryons interacting with pions can be studied on the lattice without encountering complex action problems. In our formulation one can also decide non-perturbatively if the chiral quark model of Georgi and Manohar provides an appropriate low-energy description of QCD. If so, one could understand why the non-relativistic quark model works.
Dynamical mass generation in pseudoquantum electrodynamics with four-fermion interactions
NASA Astrophysics Data System (ADS)
Alves, Van Sérgio; Junior, Reginaldo O. C.; Marino, E. C.; Nascimento, Leandro O.
2017-08-01
We describe dynamical symmetry breaking in a system of massless Dirac fermions with both electromagnetic and four-fermion interactions in (2 +1 ) dimensions. The former is described by the pseudo quantum electrodynamics, and the latter is given by the so-called Gross-Neveu action. We apply the Hubbard-Stratonovich transformation and the large-Nf expansion in our model to obtain a Yukawa action. Thereafter, the presence of a symmetry broken phase is inferred from the nonperturbative Schwinger-Dyson equation for the electron propagator. This is the physical solution whenever the fine-structure constant is larger than a critical value αc(D Nf). In particular, we obtain the critical coupling constant αc≈0.36 for D Nf=8 ., where D =2 , 4 corresponds to the SU(2) and SU(4) cases, respectively, and Nf is the flavor number. Our results show a decreasing of the critical coupling constant in comparison with the case of pure electromagnetic interaction, thus yielding a more favorable scenario for the occurrence of dynamical symmetry breaking. Nevertheless, the number of renormalized masses is not changed by the four-fermion interaction within our approximation. For two-dimensional materials, in application in condensed matter systems, it implies an energy gap at the Dirac points or valleys of the honeycomb lattice.
Confinement and dynamical chiral symmetry breaking in QED3
Bashir, A.; Raya, A.; Cloeet, I. C.; Roberts, C. D.
2008-11-15
We establish that QED3 can possess a critical number of flavors, N{sub f}{sup c}, associated with dynamical chiral symmetry breaking if, and only if, the fermion wave function renormalization and photon vacuum polarization are homogeneous functions at infrared momenta when the fermion mass function vanishes. The Ward identity entails that the fermion-photon vertex possesses the same property and ensures a simple relationship between the homogeneity degrees of each of these functions. Simple models for the photon vacuum polarization and fermion-photon vertex are used to illustrate these observations. The existence and value of N{sub f}{sup c} are contingent upon the precise form of the vertex but any discussion of gauge dependence is moot. We introduce an order parameter for confinement. Chiral symmetry restoration and deconfinement are coincident owing to an abrupt change in the analytic properties of the fermion propagator when a nonzero scalar self-energy becomes insupportable.
Confinement and dynamical chiral symmetry breaking in QED3.
Bashir, A.; Raya, A.; Cloet, I. C.; Roberts, C. D.; Univ. Michoacana de San Nicolas de Hidalgo
2008-01-01
We establish that QED3 can possess a critical number of flavors, Nfc, associated with dynamical chiral symmetry breaking if, and only if, the fermion wave function renormalization and photon vacuum polarization are homogeneous functions at infrared momenta when the fermion mass function vanishes. The Ward identity entails that the fermion-photon vertex possesses the same property and ensures a simple relationship between the homogeneity degrees of each of these functions. Simple models for the photon vacuum polarization and fermion-photon vertex are used to illustrate these observations. The existence and value of Nfc are contingent upon the precise form of the vertex but any discussion of gauge dependence is moot. We introduce an order parameter for confinement. Chiral symmetry restoration and deconfinement are coincident owing to an abrupt change in the analytic properties of the fermion propagator when a nonzero scalar self-energy becomes insupportable.
Simple Evaluation of the Chiral Jacobian with the Overlap Dirac Operator
NASA Astrophysics Data System (ADS)
Suzuki, H.
1999-07-01
The chiral Jacobian, which is defined with Neuberger's overlap Dirac operator of the lattice fermion, is explicitly evaluated in the continuum limit without expanding it in the gauge coupling constant. Our calculational scheme is simple and straightforward. We determine a coefficient of the chiral anomaly for general values of the mass parameter and the Wilson parameter of the overlap Dirac operator.
Camacho-Muñoz, Dolores; Petrie, Bruce; Castrignanò, Erika; Kasprzyk-Hordern, Barbara
2016-08-01
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.
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
Chirally symmetric strong and electroweak interactions
NASA Astrophysics Data System (ADS)
Rajpoot, Subhash
1988-07-01
Strong and electroweak interactions may be a relic of the spontaneous breakdown of a chirally symmetric colour-flavour gauge group. The minimum possibility of such a structure that is symmetric between left and right is SU(3) L×SU(3) R×SU(2) L×SU(2) R×U(1) B- L where quantum chromodynamics originates in the chiral colour group SU(3) L×SU(3) R and the electroweak interaction originates in the ambidextrous electroweak interaction group SU L×SU(2) R×U(1) B- L. The chiral anomalies are cancelled by adding a set of fermions that transform as singlets under the weak interaction group SU(2) L×SU(2) R. This model requires only three Higgs representations to break the proposed gauge symmetry to SU(3) C×U(1) em and give masses to all the quarks and leptons of the theory. All fermion masses are “see-saw” masses.
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.
Boson formulation of fermion field theories
Ha, Y.K.
1984-04-15
The nonperturbative connection between a canonical Fermi field and a canonical Bose field in two dimensions is developed and its validity verified according to the tenets of quantum field theory. We advocate the point of view that a boson formulation offers a unifying theme in understanding the structure of many theories. This is illustrated by the boson formulation of a multifermion theory with chiral and internal symmetries. Many features of the massless theory, such as dynamical mass generation with asymptotic-freedom behavior, hidden chiral symmetry, and connections with models of apparently different internal symmetries, are readily transparent through such fermion-boson metamorphosis.
Fermion masses and mixing in SU(5)×D4 × U(1) model
NASA Astrophysics Data System (ADS)
Ahl Laamara, R.; Loualidi, M. A.; Miskaoui, M.; Saidi, E. H.
2017-03-01
We propose a supersymmetric SU (5) ×Gf GUT model with flavor symmetry Gf =D4 × U (1) providing a good description of fermion masses and mixing. The model has twenty eight free parameters, eighteen are fixed to produce approximative experimental values of the physical parameters in the quark and charged lepton sectors. In the neutrino sector, the TBM matrix is generated at leading order through type I seesaw mechanism, and the deviation from TBM studied to reconcile with the phenomenological values of the mixing angles. Other features in the charged sector such as Georgi-Jarlskog relations and CKM mixing matrix are also studied.
Neutrino democracy, fermion mass hierarchies, and proton decay from 5D SU(5)
NASA Astrophysics Data System (ADS)
Shafi, Qaisar; Tavartkiladze, Zurab
2003-04-01
The explanation of various observed phenomena such as large angle neutrino oscillations, hierarchies of charged fermion masses and CKM mixings, and apparent baryon number conservation may have a common origin. We show how this could occur in 5D SUSY SU(5) supplemented by a U(1) flavor symmetry and additional matter supermultiplets called “copies.” In addition, the proton decays into p→Kν, with an estimated lifetime of the order of 1033-1036 yr. Other decay channels include Ke and Kμ with comparable rates. We also expect that BR(μ→eγ)˜BR(τ→μγ).
Evading Weinberg's no-go theorem to construct mass dimension one fermions: Constructing darkness
NASA Astrophysics Data System (ADS)
Vir Ahluwalia, Dharam
2017-06-01
Recent theoretical work reporting the construction of a new quantum field of spin one-half fermions with mass dimension one requires that Weinberg's no-go theorem must be evaded. Here we show how this comes about. The essence of the argument is to first define a quantum field with due care being taken in fixing the locality phases attached to each of the expansion coefficients. The second ingredient is to systematically construct the dual of the expansion coefficients to define the adjoint of the field. The Feynman-Dyson propagator constructed from the vacuum expectation value of the field and its adjoint then yields the mass dimensionality of the field. For a quantum field constructed from a complete set of eigenspinors of the charge conjugation operator, with locality phases judiciously chosen, the Feynman-Dyson propagator determines the mass dimension of the field to be one, rather than three halves. The Lorentz symmetry is preserved, locality anticommutators are satisfied, without violating fermionic statistics as needed for the spin one-half field.
Ginsparg-Wilson fermions: A study in the Schwinger model
NASA Astrophysics Data System (ADS)
Chandrasekharan, Shailesh
1999-05-01
The qualitative features of Ginsparg-Wilson fermions, as formulated by Neuberger, coupled to two-dimensional U(1) gauge theory are studied. The role of the Wilson mass parameter in changing the number of massless flavors in the theory and its connection with the index of the Dirac operator is studied. Although the index of the Dirac operator is not related to the geometric definition of the topological charge for strong couplings, the two start to agree as soon as one goes to moderately weak couplings. This produces the desired singularity in the quenched chiral condensate which appears to be very difficult to reproduce with staggered fermions. The fermion determinant removes the singularity and reproduces the known chiral condensate and the meson mass within understandable errors.
Young, Brandy L; Cooks, R G; Madden, Michelle C; Bair, Michael; Jia, Jingpin; Aubry, Anne-Françoise; Miller, Scott A
2007-04-11
The present work demonstrates the application and validation of a mass spectrometry method for quantitative chiral purity determination. The particular compound analyzed is Flindokalner, a Bristol-Myers Squibb drug candidate for post-stroke neuroprotection. Chiral quantification of Flindokalner was achieved using tandem mass spectrometry (MS/MS) and the kinetic method, a gas phase method used for thermochemical and chiral determinations. The MS/MS method was validated and benchmarked against two separate chromatographic techniques, chiral high performance liquid chromatography with ultra-violet detection (LC/UV) and achiral high performance liquid chromatography with circular dichroism detection (LC/CD). The chiral purity determination of Flindokalner using MS/MS proved to be rapid (3 min run time for each sample) and to have accuracy and precision comparable to the chiral LC/UV and achiral LC/CD methods. This method represents an alternative to commonly used chromatographic techniques as a means of chiral purity determination and is particularly useful in rapid screening experiments.
Matsuzaki, Shinya; Yamawaki, Koichi
2014-08-22
We propose a scale-invariant chiral perturbation theory of the pseudo-Nambu-Goldstone bosons of chiral symmetry (pion π) as well as the scale symmetry (dilaton ϕ) for large N(f) QCD. The resultant dilaton mass M(ϕ) reads M(ϕ)(2) = m(ϕ)(2)+1/4(3-γ(m))(1+γ(m))(2N(f)F(π)(2)/F(ϕ)(2))m(π)(2)+(chiral log corrections), where m(ϕ), m(π), γ(m), F(π), and F(ϕ) are the dilaton mass in the chiral limit, the pion mass, the mass anomalous dimension, and the decay constants of π and ϕ, respectively. The chiral extrapolation of the lattice data, when plotted as M(ϕ)(2) versus m(π)(2), then simultaneously determines (m(ϕ), F(ϕ)) of the technidilaton in walking technicolor with γ(m) ≃ 1. The chiral logarithmic corrections are explicitly given.
Compressibility, zero sound, and effective mass of a fermionic dipolar gas at finite temperature
Kestner, J. P.; Das Sarma, S.
2010-09-15
The compressibility, zero-sound dispersion, and effective mass of a gas of fermionic dipolar molecules is calculated at finite temperature for one-, two-, and three-dimensional uniform systems, and in a multilayer quasi-two-dimensional system. The compressibility is nonmonotonic in the reduced temperature, T/T{sub F}, exhibiting a maximum at finite temperature. This effect might be visible in a quasi-low-dimensional experiment, providing a clear signature of the onset of many-body quantum degeneracy effects. The collective mode dispersion and effective mass show similar nontrivial temperature and density dependence. In a quasi-low-dimensional system, the zero-sound mode may propagate at experimentally attainable temperatures.
Sotnikov, Andrii; Cocks, Daniel; Hofstetter, Walter
2012-08-10
We study magnetic phases of two-component mixtures of ultracold fermions with repulsive interactions in optical lattices in the presence of hopping imbalance. Our analysis is based on dynamical mean-field theory (DMFT) and its real-space generalization at finite temperature. We study the temperature dependence of the transition into the ordered state as a function of the interaction strength and the imbalance parameter in two and three spatial dimensions. We show that below the critical temperature for Néel order mass-imbalanced mixtures also exhibit a charge-density wave, which provides a directly observable signature of the ordered state. For the trapped system, we compare our results obtained by real-space DMFT to a local-density approximation. We calculate the entropy for a wide range of parameters and identify regions, in which mass-imbalanced mixtures could have clear advantages over balanced ones for the purpose of obtaining and detecting quantum magnetism.
Kupi, Gabor
2008-01-15
We give a gravitational upper limit for the mass of static degenerate fermionic dark matter objects. The treatment we use includes fully relativistic equations for describing the static solutions of these objects. We study the influence of the annihilation of the particles on this mass limit. We give the change of its value over the age of the Universe with annihilation cross sections relevant for such fermions constituting the dark matter. Our calculations take into account the possibility of Dirac as well Majorana spinors.
Role of the electron mass in damping chiral plasma instability in Supernovae and neutron stars
NASA Astrophysics Data System (ADS)
Grabowska, Dorota; Kaplan, David B.; Reddy, Sanjay
2015-04-01
We show that the nonzero electron mass plays a critical role in determining the magnetic properties of neutron stars by suppressing the generation of the chiral charge density needed to trigger a strong chiral plasma instability during the core collapse of supernovae. This instability has been proposed as a plausible mechanism for generating extremely large helical magnetic fields in neutron stars at their birth; the mechanism relies on the generation of a large nonequilibrium chiral charge density via electron capture reactions that selectively deplete left-handed electrons during core collapse and the early evolution of the protoneutron star. Our calculation shows that the electron chirality violation rate induced by Rutherford scattering, despite being suppressed by the smallness of the electron mass relative to the electron chemical potential, is still fast compared to the weak interaction electron capture rate. The resulting asymmetry between right- and left-handed electron densities is therefore unlikely to attain an astrophysically relevant magnitude.
NASA Astrophysics Data System (ADS)
Abdel-Rehim, A.; Alexandrou, C.; Burger, F.; Constantinou, M.; Dimopoulos, P.; Frezzotti, R.; Hadjiyiannakou, K.; Helmes, C.; Jansen, K.; Jost, C.; Kallidonis, C.; Knippschild, B.; Kostrzewa, B.; Koutsou, G.; Liu, L.; Mangin-Brinet, M.; Ottnad, K.; Petschlies, M.; Pientka, G.; Rossi, G. C.; Urbach, C.; Wenger, U.; Werner, M.
2017-05-01
We present physics results from simulations of QCD using Nf=2 dynamical Wilson twisted mass fermions at the physical value of the pion mass. These simulations are enabled by the addition of the clover term to the twisted mass quark action. We show evidence that compared to previous simulations without this term, the pion mass splitting due to isospin breaking is almost completely eliminated. Using this new action, we compute the masses and decay constants of pseudoscalar mesons involving the dynamical up and down as well as valence strange and charm quarks at one value of the lattice spacing, a ≈0.09 fm . Further, we determine renormalized quark masses as well as their scale-independent ratios, in excellent agreement with other lattice determinations in the continuum limit. In the baryon sector, we show that the nucleon mass is compatible with its physical value and that the masses of the Δ baryons do not show any sign of isospin breaking. Finally, we compute the electron, muon and tau lepton anomalous magnetic moments and show the results to be consistent with extrapolations of older ETMC data to the continuum and physical pion mass limits. We mostly find remarkably good agreement with phenomenology, even though we cannot take the continuum and thermodynamic limits.
NASA Astrophysics Data System (ADS)
Xia, Lifang
In the first part of this thesis, we use the generalized Landau-level represen- tation to study the effect of screening on the properties of the graphene quantum Hall states with integer filling factors. The analysis is performed in the low-energy Dirac model in the mean-field approximation, in which the long-range Coulomb in- teraction is modified by the one-loop static screening effects. The solutions demon- strate that static screening leads to a substantial suppression of the gap parameters in the quantum Hall states with a broken U (4) flavor symmetry. The results of the temperature dependence of the energy gaps mimic well the temperature dependence of the activation energies measured in experiment. The Landau-level running of the quasiparticle dynamical parameters could be tested via optical studies of the integer quantum Hall states. In the second part, by using the generalized Landau-level representation, we study the interaction induced chiral asymmetry in cold QED plasma beyond the weak-field approximation. The chiral shift and the parity-even chiral chemical potential function are obtained numerically and are found peaking near the Fermi surface and increases and decreases with the Landau level index, respectively. The results are used to quantify the chiral asymmetry of the Fermi surface in dense QED matter. The chiral asymmetry appears to be rather small even in the strongest mag- netic fields and at the highest stellar densities. However, the analogous asymmetry can be substantial in the case of dense quark matter.
Fermion Masses and Mixing in SUSY Grand Unified Gauge Models with Extended Gut Gauge Groups
Chou, Chih-Lung
2005-04-05
The authors discuss a class of supersymmetric (SUSY) grand unified gauge (GUT) models based on the GUT symmetry G x G or G x G x G, where G denotes the GUT group that has the Standard Model symmetry (SU(3){sub c} x SU(2){sub L} x U(1){sub Y}) embedded as a subgroup. As motivated from string theory, these models are constructed without introducing any Higgs field of rani two or higher. Thus all the Higgs fields are in the fundamental representations of the extended GUT symmetry or, when G = SO(10), in the spinorial representation. These Higgs fields, when acquiring their vacuum expectation values, would break the extended GUT symmetry down to the Standard Model symmetry. In this dissertation, they argue that the features required of unified models, such as the Higgs doublet-triplet splitting, proton stability, and the hierarchy of fermion masses and mixing angles, could have natural explanations in the framework of the extended SUSY GUTs. Furthermore, they argue that the frameworks used previously to construct SO(10) GUT models using adjoint Higgs fields can naturally arise from the SO(10) x SO(10) and SO(10) x SO(10) x SO(10) models by integrating out heavy fermions. This observation thus suggests that the traditional SUSY GUT SO(10) theories can be viewed as the low energy effective theories generated by breaking the extended GUT symmetry down to the SO(10) symmetry.
NASA Astrophysics Data System (ADS)
Val'kov, V. V.; Zlotnikov, A. O.
2016-10-01
For the system of strongly correlated electrons on a triangular lattice, the possibility of coexisting superconductivity with the chiral order parameter and the 120°-type noncollinear spin ordering is demonstrated. The integral self-consistency equation for the superconducting order parameter is derived using the diagram technique for Hubbard operators taking into account the spin structure, exchange interaction within two coordination spheres, and intersite Coulomb repulsion.
Baryon Resonances from a Novel Fat-Link Fermion Action
W. Melnitchouk; S. Bilson-Thompson; F. D. R. Bonnet; P. D. Coddington; F. X. Lee; D. B. Leinweber; A. G. Williams; J. M. Zanotti; J. B. Zhang
2001-07-01
We present first results for masses of positive and negative parity excited baryons in lattice QCD using an O(a{sup 2}) improved gluon action and a Fat Link Irrelevant Clover (FLIC) fermion action in which only the irrelevant operators are constructed with fat links. The results are in agreement with earlier calculations of N* resonances using improved actions and exhibit a clear mass splitting between the nucleon and its chiral partner, even for the Wilson fermion action. The results also indicate a splitting between the lowest J{sup P}=1/2{sup -} states for the standard nucleon interpolating fields.
The fermion mass hierarchy in models with warped extra dimensions and a bulk Higgs
NASA Astrophysics Data System (ADS)
Archer, Paul R.
2012-09-01
The phenomenological implications of allowing the Higgs to propagate in both AdS5 and a class of asymptotically AdS spaces are considered. Without tuning, the vacuum expectation value (VEV) of the Higgs is peaked towards the IR tip of the space and hence such a scenario still offers a potential resolution to the gauge-hierarchy problem. When the exponent of the Higgs VEV is approximately two and one assumes order one Yukawa couplings, then the fermion Dirac mass term is found to range from ~ 10-5 eV to ~ 200 GeV in approximate agreement with the observed fermion masses. However, this result is sensitive to the exponent of the Higgs VEV, which is a free parameter. This paper offers a number of phenomenological and theoretical motivations for considering an exponent of two to be the optimal value. In particular, the exponent is bounded from below by the Breitenlohner-Freedman bound and the requirement that the dual theory resolves the gauge hierarchy problem. While, in the model considered, if the exponent is too large, electroweak symmetry may not be broken. In addition, the holographic method is used to demonstrate, in generality, that the flatter the Higgs VEV, the smaller the contribution to the electroweak T parameter. In addition, the constraints from a large class of gauge mediated and scalar mediated flavour changing neutral currents, will be at minimal values for flatter Higgs VEVs. Some initial steps are taken to investigate the physical scalar degrees of freedom that arise from a mixing between the W 5 /Z 5 components and the Higgs components.
Supersymmetric renormalisation group fixed points and third generation fermion mass predictions
Froggatt, C.D.; Moorhouse, R.G.; Knowles, I.G.
1992-09-01
We present a supersymmetric renormalization group fixed point determination of the third generation fermion masses, in which the large mass ratio between the top and bottom quarks is attributed to a hierarchy in the vacuum expectation values of the two Higgs doublets. Above a supersymmetry breaking scale, M{sub s}, we use the minimal supersymmetric standard model with a transition at M{sub s} to the standard model with only one Higgs- doublet effective. The mass predictions result from renormalization group evolution of large Yukawa couplings at M{sub x} {approximately} 1016 GeV. Averaging over a wide range of these couplings, not subject to any symmetry requirements, gives m{sub t} = 184.3{plus_minus}6.8 GeV, m{sub b} = 4.07{plus_minus}0.33 GeV, m{sub {tau}} = 1.78{plus_minus}0.33 GeV and a light Higgs mass m{sub h}o = 121.8{plus_minus}4.3 GeV for M{sub s} = 1 TeV and {alpha}{sub s} (M{sub z}) = 0.125.
Chiral gauge theories and a dirac neutrino - Dark matter connection
Hernandez, Daniel
2016-06-21
It is proposed 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. A new gauge symmetry U(1){sub ν} is required if light fermionic new states are to exist. Anomaly cancellations mandate the existence of several new fields with nontrivial U(1){sub ν} charges. A general technique to write down chiral-fermions-only models that are at least anomaly-free under a U(1) gauge symmetry is described. A concrete example that provides a Dark Matter candidate and leads to parametrically small Dirac neutrino masses is further developed.
Fermion localization on thick branes
Melfo, Alejandra; Pantoja, Nelson; Tempo, Jose David
2006-02-15
We consider chiral fermion confinement in scalar thick branes, which are known to localize gravity, coupled through a Yukawa term. The conditions for the confinement and their behavior in the thin-wall limit are found for various different BPS branes, including double walls and branes interpolating between different AdS{sub 5} spacetimes. We show that only one massless chiral mode is localized in all these walls, whenever the wall thickness is keep finite. We also show that, independently of wall's thickness, chiral fermionic modes cannot be localized in dS{sub 4} walls embedded in a M{sub 5} spacetime. Finally, massive fermions in double wall spacetimes are also investigated. We find that, besides the massless chiral mode localization, these double walls support quasilocalized massive modes of both chiralities.
Baik, Seung Su; Kim, Keun Su; Yi, Yeonjin; Choi, Hyoung Joon
2015-12-09
Thin flakes of black phosphorus (BP) are a two-dimensional (2D) semiconductor whose energy gap is predicted being sensitive to the number of layers and external perturbations. Very recently, it was found that a simple method of potassium (K) doping on the surface of BP closes its band gap completely, producing a Dirac semimetal state with a linear band dispersion in the armchair direction and a quadratic one in the zigzag direction. Here, based on first-principles density functional calculations, we predict that, beyond the critical K density of the gap closure, 2D massless Dirac Fermions (i.e., Dirac cones) emerge in K-doped few-layer BP, with linear band dispersions in all momentum directions, and the electronic states around Dirac points have chiral pseudospins and Berry's phase. These features are robust with respect to the spin-orbit interaction and may lead to graphene-like electronic transport properties with greater flexibility for potential device applications.
Fermion localization and resonances on a deSitter thick brane
NASA Astrophysics Data System (ADS)
Liu, Yu-Xiao; Yang, Jie; Zhao, Zhen-Hua; Fu, Chun-E.; Duan, Yi-Shi
2009-09-01
In C. A. S. Almeida, R. Casana, M. M. Ferreira, Jr., and A. R. Gomes, Phys. Rev. DPRVDAQ1550-7998 79, 125022 (2009)10.1103/PhysRevD.79.125022, the simplest Yukawa coupling ηΨ¯ϕχΨ 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 ηΨ¯ϕkΨ with positive odd integer k. A set of massive fermionic resonances for both chiralities is obtained when provided large coupling constant η. 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.
Possible Aoki phase for staggered fermions
Aubin, C.; Wang Qinghai
2004-12-01
The phase diagram for staggered fermions is discussed in the context of the staggered chiral Lagrangian, extending previous work on the subject. When the discretization errors are significant, there may be an Aoki-like phase for staggered fermions, where the remnant SO(4) taste-symmetry is broken down to SO(3). We solve explicitly for the mass spectrum in the 3-flavor degenerate mass case and discuss qualitatively the 2+1-flavor case. From numerical results we find that current simulations are outside the staggered-Aoki phase. As for near-future simulations with more-improved versions of the staggered action, it seems unlikely that these will be in the Aoki phase for any realistic value of the quark mass, although the evidence is not conclusive.
Fermion boson metamorphosis in field theory
Ha, Y.K.
1982-01-01
In two-dimensional field theories many features are especially transparent if the Fermi fields are represented by non-local expressions of the Bose fields. Such a procedure is known as boson representation. Bilinear quantities appear in the Lagrangian of a fermion theory transform, however, as simple local expressions of the bosons so that the resulting theory may be written as a theory of bosons. Conversely, a theory of bosons may be transformed into an equivalent theory of fermions. Together they provide a basis for generating many interesting equivalences between theories of different types. In the present work a consistent scheme for constructing a canonical Fermi field in terms of a real scalar field is developed and such a procedure is valid and consistent with the tenets of quantum field theory is verified. A boson formulation offers a unifying theme in understanding the structure of many theories. This is illustrated by the boson formulation of a multifermion theory with chiral and internal symmetries. The nature of dynamical generation of mass when the theory undergoes boson transmutation and the preservation of continuous chiral symmetry in the massive case are examined. The dynamics of the system depends to a great extent on the specific number of fermions and different models of the same system can have very different properties. Many unusual symmetries of the fermion theory, such as hidden symmetry, duality and triality symmetries, are only manifest in the boson formulation. The underlying connections between some models with U(N) internal symmetry and another class of fermion models built with Majorana fermions which have O(2N) internal symmetry are uncovered.
Canonical approach to Ginsparg-Wilson fermions
Matsui, Kosuke; Okamoto, Tomohito; Fujiwara, Takanori
2005-06-01
Based upon the lattice Dirac operator satisfying the Ginsparg-Wilson relation, we investigate canonical formulation of massless fermion on the spatial lattice. For free fermion system exact chiral symmetry can be implemented without species doubling. In the presence of gauge couplings the chiral symmetry is violated. We show that the divergence of the axial vector current is related to the chiral anomaly in the classical continuum limit.
S4 flavor symmetry and fermion masses: towards a grand unified theory of flavor
NASA Astrophysics Data System (ADS)
Hagedorn, Claudia; Lindner, Manfred; Mohapatra, Rabindra N.
2006-06-01
Pursuing a bottom-up approach to explore which flavor symmetry could serve as an explanation of the observed fermion masses and mixings, we discuss an extension of the standard model (SM) where the flavor structure for both quarks and leptons is determined by a spontaneously broken S4 and the requirement that its particle content is embeddable simultaneously into the conventional SO(10) grand unified theory (GUT) and a continuous flavor symmetry Gf like SO(3)f or SU(3)f. We explicitly provide the Yukawa and the Higgs sector of the model and show its viability in two numerical examples which arise as small deviations from rank one matrices. In the first case, the corresponding mass matrix is democratic and in the second one only its 2-3 block is non-vanishing. We demonstrate that the Higgs potential allows for the appropriate vacuum expectation value (VEV) configurations in both cases, if CP is conserved. For the first case, the chosen Yukawa couplings can be made natural by invoking an auxiliary Z2 symmetry. The numerical study we perform shows that the best-fit values for the lepton mixing angles θ12 and θ23 can be accommodated for normal neutrino mass hierarchy. The results for the quark mixing angles turn out to be too small. Furthermore the CP-violating phase δ can only be reproduced correctly in one of the examples. The small mixing angle values are likely to be brought into the experimentally allowed ranges by including radiative corrections. Interestingly, due to the S4 symmetry the mass matrix of the right-handed neutrinos is proportional to the unit matrix.
Eta(') mass and chiral symmetry breaking at large N(c) and N(f).
Girlanda, L; Stern, J; Talavera, P
2001-06-25
We propose a method for implementing the large- N(c), large-N(f) limit of QCD at the effective Lagrangian level. Depending on the value of the ratio N(f)/N(c), different patterns of chiral symmetry breaking can arise, leading in particular to different behaviors of the eta(') mass in the combined large-N limit.
Even- and Odd-Parity Charmed Meson Masses in Heavy Hadron Chiral Perturbation Theory
Thomas Mehen; Roxanne Springer
2005-03-01
We derive mass formulae for the ground state, J{sup P} = 0{sup -} and 1{sup -}, and first excited even-parity, J{sup P} = 0{sup +} and 1{sup +}, charmed mesons including one loop chiral corrections and {Omicron}(1/m{sub c}) counterterms in heavy hadron chiral perturbation theory. We show a variety of fits to the current data. We find that certain parameter relations in the parity doubling model are not renormalized at one loop, providing a natural explanation for the equality of the hyperfine splittings of ground state and excited doublets.
Fermions on thick branes in the background of sine-Gordon kinks
Liu Yuxiao; Zhang Lida; Duan Yishi; Zhang Lijie
2008-09-15
A class of thick branes in the background of sine-Gordon kinks with a scalar potential V({phi})=p(1+cos(2{phi}/q)) was constructed by R. Koley and S. Kar [Classical Quantum Gravity 22, 753 (2005)]. In this paper, in the background of the warped geometry, we investigate the issue of localization of spin-1/2 fermions on these branes in the presence of two types of scalar-fermion couplings: {eta}{psi}{phi}{psi} and {eta}{psi}sin{phi}{psi}. By presenting the mass-independent potentials in the corresponding Schroedinger equations, we obtain the lowest Kaluza-Klein modes and a continuous gapless spectrum of Kaluza-Klein states with m{sup 2}>0 for both types of couplings. For the Yukawa coupling {eta}{psi}{phi}{psi}, the effective potential of the right chiral fermions for positive q and {eta} is always positive; hence only the effective potential of the left chiral fermions could trap the corresponding zero mode. This is a well-known conclusion which is discussed extensively in the literature. However, for the coupling {eta}{psi}sin{phi}{psi}, the effective potential of the right chiral fermions for positive q and {eta} is no longer always positive. Although the value of the potential at the location of the brane is still positive, it has a series of wells and barriers on each side, which ensures that the right chiral fermion zero mode could be trapped. Thus we may draw the following remarkable conclusion: for positive {eta} and q, the potentials of both the left and right chiral fermions could trap the corresponding zero modes under certain restrictions.
Fermion masses and proton decay in a minimal five-dimensional SO(10) model
NASA Astrophysics Data System (ADS)
Alciati, Maria Laura; Feruglio, Ferruccio; Lin, Yin; Varagnolo, Alvise
2006-11-01
We propose a minimal SO(10) model in 5 space-time dimensions. The single extra spatial dimension is compactified on the orbifold S1/(Z2 × Z2') reducing the gauge group to that of Pati-Salam SU(4)C × SU(2)L × SU(2)R. The breaking down to the standard model group is obtained through an ordinary Higgs mechanism taking place at the Pati-Salam brane, giving rise to a proper gauge coupling unification. We achieve a correct description of fermion masses and mixing angles by describing first and second generations as bulk fields, and by embedding the third generation into four multiplets located at the Pati-Salam brane. The Yukawa sector is simple and compact and predicts a neutrino spectrum of normal hierarchy type. Concerning proton decay, dimension five operators are absent and the essentially unique localization of matter multiplets implies that the minimal couplings between the super-heavy gauge bosons and matter fields are vanishing. Non-minimal interactions are allowed but the resulting dimension six operators describing proton decay are too suppressed to produce observable effects, even in future, super-massive detectors.
Fermion mass generation in SO(10) with a unified Higgs sector
NASA Astrophysics Data System (ADS)
Babu, K. S.; Gogoladze, Ilia; Nath, Pran; Syed, Raza M.
2006-10-01
An analysis of generating fermion masses via cubic couplings in SO(10) grand unification with a unified Higgs sector is given. The new framework utilizes a single pair of vector-spinor representation 144+144¯ to break the gauge symmetry all the way to SU(3)C×U(1)em. Typically the matter-Higgs couplings in this framework are quartic and lead to naturally suppressed Yukawa couplings for the first two generations. Here we show that much larger third generation couplings naturally arise at the cubic level with additional matter in 10-plet and 45-plet representations of SO(10). Thus the physical third generation is a mixture of 16, 10, and 45-plet representations while the remaining components become superheavy and are removed from the low energy spectrum. In this scenario it is possible to understand the heaviness of the top in a natural way since the analysis generates a hierarchy in the Yukawa couplings so that ht/hb≫1 where ht(hb) are the top (bottom) Yukawa couplings. It is then possible to realize values of tanβ as low as 2, which also helps to stabilize the proton.
Competing mechanisms of chiral symmetry breaking in a generalized Gross-Neveu model
Boehmer, Christian; Thies, Michael
2010-05-15
Chiral symmetry of the 2-dimensional chiral Gross-Neveu model is broken explicitly by a bare mass term as well as a splitting of scalar and pseudoscalar coupling constants. The vacuum and light hadrons--mesons and baryons which become massless in the chiral limit--are explored analytically in leading order of the derivative expansion by means of a double sine-Gordon equation. Depending on the parameters, this model features new phenomena as compared to previously investigated 4-fermion models: spontaneous breaking of parity, a nontrivial chiral vacuum angle, twisted kinklike baryons whose baryon number reflects the vacuum angle, crystals with alternating baryons, and appearance of a false vacuum.
Complex Langevin dynamics for chiral random matrix theory
NASA Astrophysics Data System (ADS)
Mollgaard, A.; Splittorff, K.
2013-12-01
We apply complex Langevin dynamics to chiral random matrix theory at nonzero chemical potential. At large quark mass, the simulations agree with the analytical results while incorrect convergence is found for small quark masses. The region of quark masses for which the complex Langevin dynamics converges incorrectly is identified as the region where the fermion determinant frequently traces out a path surrounding the origin of the complex plane during the Langevin flow. This links the incorrect convergence to an ambiguity in the Langevin force due to the presence of the logarithm of the fermion determinant in the action.
Confinement, quark mass functions, and spontaneous chiral symmetry breaking in Minkowski space
Biernat, Elmar P.; Gross, Franz L.; Pena, Teresa; Stadler, Alfred
2014-01-01
We formulate the covariant equations for quark-antiquark bound states in Minkowski space in the framework of the Covariant Spectator Theory. The quark propagators are dressed with the same kernel that describes the interaction between different quarks. We show that these equations are charge conjugation invariant, and that in the chiral limit of vanishing bare quark mass, a massless pseudoscalar bound state is produced in a Nambu--Jona-Lasinio (NJL) mechanism, which is associated with the Goldstone boson of spontaneous chiral symmetry breaking. In this introductory paper we test the formalism by using a simplified kernel consisting of a momentum-space $\\delta$-function with a vector Lorentz structure, to which one adds a mixed scalar and vector confining interaction. The scalar part of the confining interaction is not chirally invariant by itself, but decouples from the equations in the chiral limit and therefore allows the NJL mechanism to work. With this model we calculate the quark mass function, and we compare our Minkowski-space results to LQCD data obtained in Euclidean space. In a companion paper we apply this formalism to a calculation of the pion form factor.
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.
Engelhardt, M.; Musch, B.; Bhattacharya, T.; ...
2014-06-23
Here, lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs) in a nucleon are performed based on a definition of TMDs via hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for the lattice calculation. Using a RBC/UKQCD domain wall fermion ensemble corresponding to a pion mass of 297 MeV, on a lattice with spacing 0.084 fm, selected TMD observables are accessed and compared to previous exploration at heavier pion masses on coarser lattices.
Engelhardt, Michael; Musch, Bernhard; Bhattacharya, Tanmoy; Gupta, Rajan; Hagler, Phillip; Negele, John; Pochinsky, Andrew; Shafer, Andreas; Syritsyn, Sergey; Yoon, Boram
2014-12-01
Lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs) in a nucleon are performed based on a definition of TMDs via hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for the lattice calculation. Using a RBC/UKQCD domain wall fermion ensemble corresponding to a pion mass of 297MeV, on a lattice with spacing 0.084fm, selected TMD observables are accessed and compared to previous explorations at heavier pion masses on coarser lattices.
Engelhardt, M.; Musch, B.; Bhattacharya, T.; Gupta, R.; Hagler, P.; Negele, J.; Pochinsky, A.; Schafer, A.; Syritsyn, S.; Yoon, B.
2014-06-23
Here, lattice QCD calculations of transverse momentum-dependent parton distributions (TMDs) in a nucleon are performed based on a definition of TMDs via hadronic matrix elements of quark bilocal operators containing staple-shaped gauge connections. A parametrization of the matrix elements in terms of invariant amplitudes serves to cast them in the Lorentz frame preferred for the lattice calculation. Using a RBC/UKQCD domain wall fermion ensemble corresponding to a pion mass of 297 MeV, on a lattice with spacing 0.084 fm, selected TMD observables are accessed and compared to previous exploration at heavier pion masses on coarser lattices.
THE PARITY PARTNER OF THE NUCLEON IN QUENCHED QCD WITH DOMAIN WALL FERMIONS
SASAKI,S.
2000-07-12
The authors present preliminary results for the mass spectrum of the nucleon and its low-lying excited states from quenched lattice QCD using the domain wall fermion method which preserves the chiral symmetry at finite lattice cutoff. Definite mass splitting is observed between the nucleon and its parity partner. This splitting grows with decreasing valence quark mass. They also present preliminary data regarding the first positive-parity excited state.
Masses and decay constants of pions and kaons in mixed-action staggered chiral perturbation theory
NASA Astrophysics Data System (ADS)
Bailey, Jon A.; Kim, Jongjeong; Lee, Weonjong; Kim, Hyung-Jin; Yoon, Boram
2017-08-01
Lattice QCD calculations with different staggered valence and sea quarks can be used to improve determinations of quark masses, Gasser-Leutwyler couplings, and other parameters relevant to phenomenology. We calculate the masses and decay constants of flavored pions and kaons through next-to-leading order in staggered-valence, staggered-sea mixed-action chiral perturbation theory. We present the results in the valence-valence and valence-sea sectors, for all tastes. As in unmixed theories, the taste-pseudoscalar, valence-valence mesons are exact Goldstone bosons in the chiral limit, at nonzero lattice spacing. The results reduce correctly when the valence and sea quark actions are identical, connect smoothly to the continuum limit, and provide a way to control light quark and gluon discretization errors in lattice calculations performed with different staggered actions for the valence and sea quarks.
Locality and Scaling of Quenched Overlap Fermions
Terrence Draper; Nilmani Mathur; Jianbo Zhang; Andrei Alexandru; Ying Chen; Shao-Jing Dong; Ivan Horvath; Frank Lee; Sonali Tamhankar
2005-07-01
The overlap fermion offers the tremendous advantage of exact chiral symmetry on the lattice, but is numerically intensive. This can be made affordable while still providing large lattice volumes, by using coarse lattice spacing, given that good scaling and localization properties are established. Here, using overlap fermions on quenched Iwasaki gauge configurations, we demonstrate directly that the overlap Dirac operator's range is comfortably small in lattice units for each of the lattice spacings 0.20 fm, 0.17 fm, and 0.13 fm (and scales to zero in physical units in the continuum limit). In particular, our direct results contradict recent speculation that an inverse lattice spacing of 1 GeV is too low to have satisfactory localization. Furthermore, hadronic masses (available on the two coarser lattices) scale very well.
Chiral two- and three-nucleon forces along medium-mass isotope chains
NASA Astrophysics Data System (ADS)
Somà, V.; Cipollone, A.; Barbieri, C.; Navrátil, P.; Duguet, T.
2014-06-01
Ab initio calculations have shown that chiral two- and three-nucleon interactions correctly reproduce binding energy systematics and neutron drip lines of oxygen and nearby isotopes. Exploiting the novel Gorkov-Green's function approach applicable to genuinely open-shell nuclei, we present the first ab initio investigation of Ar, K, Ca, Sc, and Ti isotopic chains. In doing so, stringent tests of internucleon interaction models are provided in the medium-mass region of the nuclear chart. Leading chiral three-nucleon interactions are shown to be mandatory to reproduce the trend of binding energies throughout these chains and to obtain a good description of two-neutron separation energies. At the same time, nuclei in this mass region are systematically overbound by about 40 MeV. While the fundamental N =20 and 28 magic numbers do emerge from basic internucleon interactions, the former is shown to be significantly overestimated, which points to deficiencies of state-of-the-art chiral potentials. The present results demonstrate that ab initio many-body calculations can now access entire medium-mass isotopic chains including degenerate open-shell nuclei and provide a critical testing ground for modern theories of nuclear interactions.
AdS{sub 5} black holes with fermionic hair
Burrington, Benjamin A.; Liu, James T.; Sabra, W. A.
2005-05-15
The study of new Bogomol'nyi-Prasad-Sommerfield (BPS) objects in AdS{sub 5} has led to a deeper understanding of AdS/CFT. To help complete this picture, and to fully explore the consequences of the supersymmetry algebra, it is also important to obtain new solutions with bulk fermions turned on. In this paper we construct superpartners of the 1/2 BPS black hole in AdS{sub 5} using a natural set of fermion zero modes. We demonstrate that these superpartners, carrying fermionic hair, have conserved charges differing from the original bosonic counterpart. To do so, we find the R-charge and dipole moment of the new system, as well as the mass and angular momentum, defined through the boundary stress tensor. The complete set of superpartners fits nicely into a chiral representation of AdS{sub 5} supersymmetry, and the spinning solutions have the expected gyromagnetic ratio, g=1.
Observation of Weyl fermions in condensed matter
NASA Astrophysics Data System (ADS)
Ding, Hong
In 1929, a German mathematician and physicist Hermann Weyl proposed that a massless solution of the Dirac equation represents a pair of new type of particles, the so-called Weyl fermions. However, their existence in particle physics remains elusive after more than eight decades, e.g., neutrino has been regarded as a Weyl fermion in the Standard Model until it was found to have mass. Recently, significant advances in topological materials have provided an alternative way to realize Weyl fermions in condensed matter as an emergent phenomenon. Weyl semimetals are predicted as a class of topological materials that can be regarded as three-dimensional analogs of graphene breaking time reversal or inversion symmetry. Electrons in a Weyl semimetal behave exactly as Weyl fermions, which have many exotic properties, such as chiral anomaly, magnetic monopoles in the crystal momentum space, and open Fermi arcs on the surface. In this talk I will report our experimental discovery of a Weyl semimetal in TaAs by observing Fermi arcs with a characteristic spin texture in the surface states and Weyl nodes in the bulk states using angle-resolved photoemission spectroscopy.
On the dependence on the magnetic field orientation of the composite fermion effective mass
NASA Astrophysics Data System (ADS)
Gee, P. J.; Singleton, J.; Uji, S.; Aoki, H.; Foxon, C. T. B.; Harris, J. J.
1996-12-01
The composite fermion (CF) model has been strikingly successful in describing many aspects of the fractional quantum Hall effect (FQHE) observed in two-dimensional electron systems (2DES). In the CF picture, the FQHE is the integer quantum Hall effect of the CFs. In order to assess the effect of an in-plane magnetic field on the CFs we have examined the temperature dependence 0953-8984/8/49/029/img9 of the oscillations in 0953-8984/8/49/029/img10 in a high-mobility GaAs - (Ga, Al)As heterojunction close to Landau level filling factors 0953-8984/8/49/029/img11 and 0953-8984/8/49/029/img12 for many different values of 0953-8984/8/49/029/img13, the angle between the normal to the 2DES and the magnetic field. The CF energy gaps were evaluated at each angle using a variant of the Lifshitz - Kosevich approach. Close to 0953-8984/8/49/029/img11, it was found that the CF gaps at each angle could be fitted to within experimental errors using a constant CF effective mass. However, the CF effective mass was found not to follow the 0953-8984/8/49/029/img13-dependence expected for a purely 2D system; i.e. the CF energy gap at fixed 0953-8984/8/49/029/img16 grows markedly with increasing in-plane field. Around 0953-8984/8/49/029/img17 the situation is more complex, and the oscillations of the energy gaps at 0953-8984/8/49/029/img18 and 0953-8984/8/49/029/img19 as 0953-8984/8/49/029/img13 varied were interpreted using a recent model of two independent CF Landau fans separated by the Pauli spin splitting (Du R R, Yeh A S, Stormer H L, Tsui D C, Pfeiffer L N and West K W 1995 Phys. Rev. Lett. 75 3926). However, whilst the model qualitatively predicts some of the behaviour of the 0953-8984/8/49/029/img10-minima, it is unable to account for the absolute sizes of the energy gaps. In order to reproduce the gaps at 0953-8984/8/49/029/img22 and 0953-8984/8/49/029/img19 quantitatively, an angle-dependent CF mass (as observed close to 0953-8984/8/49/029/img11) is required. The data suggest
Consistency between SU(3) and SU(2) covariant baryon chiral perturbation theory for the nucleon mass
NASA Astrophysics Data System (ADS)
Ren, Xiu-Lei; Alvarez-Ruso, L.; Geng, Li-Sheng; Ledwig, Tim; Meng, Jie; Vicente Vacas, M. J.
2017-03-01
Treating the strange quark mass as a heavy scale compared to the light quark mass, we perform a matching of the nucleon mass in the SU(3) sector to the two-flavor case in covariant baryon chiral perturbation theory. The validity of the 19 low-energy constants appearing in the octet baryon masses up to next-to-next-to-next-to-leading order [1] is supported by comparing the effective parameters (the combinations of the 19 couplings) with the corresponding low-energy constants in the SU(2) sector [2]. In addition, it is shown that the dependence of the effective parameters and the pion-nucleon sigma term on the strange quark mass is relatively weak around its physical value, thus providing support to the assumption made in Ref. [2] that the SU(2) baryon chiral perturbation theory can be applied to study nf = 2 + 1 lattice QCD simulations as long as the strange quark mass is close to its physical value.
Overlap fermions on a 20 4 lattice
NASA Astrophysics Data System (ADS)
Liu, K.-F.; Dong, S.-J.; Lee, F. X.; Zhang, J. B.
2001-03-01
We report results on hadron masses, fitting of the quenched chiral log, and quark masses from Neuberger's overlap fermion on a quenched 20 4 lattice with lattice spacing a = 0.15 fm. We used the improved gauge action which is shown to lower the density of small eigenvalues for H2 as compared to the Wilson gauge action. This makes the calculation feasible on 64 nodes of CRAY-T3E. Also presented is the pion mass on a small volume (6 3 × 12 with a Wilson gauge action at β = 5.7). We find that for configurations that the topological charge Q ≠ 0, the pion mass tends to a constant and for configurations with trivial topology, it approaches zero possibly linearly with the quark mass.
Direct mass limits for chiral fourth-generation quarks in all mixing scenarios.
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.
Chiral electroweak gauge interactions
NASA Astrophysics Data System (ADS)
Rajpoot, Subhash
1990-10-01
The hypercharge U(1)Y of the standard electroweak model is split into chiral hypercharges U(1)L×U(1)R. Under the new gauge symmetry SU(2)L×U(1)L×U(1)R, quarks and leptons are left-handed doublets transforming only under SU(2)L×U(1)L and right-handed singlets transforming only under U(1)R. Consistent with the measurements of the mass of the standard massive neutral boson Z0 at the SLAC and CERN colliders and the neutral-current couplings involving neutrino beams and electron beams, the additional massive neutral gauge boson can be as light as a few hundred GeV. The model utilizes the generalized see saw mechanism of Gell-Mann, Ramond, and Slansky to give masses to all the fermions of the theory.
NASA Astrophysics Data System (ADS)
Tkachov, Grigory; Hentschel, Martina
2009-05-01
Extended defects in graphene, such as linear edges, break the translational invariance and can also have an impact on the symmetries specific to massless Dirac-type quasiparticles in this material. The paper examines the consequences of a broken Dirac fermion parity in the framework of the effective boundary conditions varying from the Berry-Mondragon mass confinement to a zigzag edge. The parity breaking reflects the structural sublattice asymmetry of zigzag-type edges and is closely related to the previously predicted time-reversal symmetric edge states. We calculate the local and global densities of the edge states and show that they carry a specific polarization resembling to some extent that of spin-polarized materials. The lack of the parity leads to a non-analytical particle-hole asymmetry in the edge-state properties. We use our findings to interpret recently observed tunneling spectra in zigzag-terminated graphene. We also propose a graphene-based tunneling device where the particle-hole asymmetric edge states result in strongly nonlinear conductance-voltage characteristics, which could be used to manipulate the tunneling transport.
Nie, Yanfang; Liu, Xiumei; Yang, Xinmei; Zhao, Zhongxi
2013-09-01
The technology of analyzing the pharmacological and toxicological properties of chiral drugs has become more commonly utilized since the knowledge of the biological actions of enantiomers has been gradually acquired during the last few decades. This work reviews the applications of chiral liquid chromatography coupled to tandem mass spectrometry (LC-MS) for the analysis of chiral pharmaceuticals since 2005. The enantioselective determinations in pharmaceutical and biomedical fields with LC-MS are classified based on three mobile phase modes, including normal phase, reversed phase and polar organic solvent, in terms of their compatibility with various ionization sources and specific applications.
NASA Astrophysics Data System (ADS)
Nomura, K.; Rodríguez-Guzmán, R.; Robledo, L. M.
2017-07-01
Spectroscopic properties of odd-mass nuclei are studied within the framework of the interacting boson-fermion model (IBFM) with parameters based on the Hartree-Fock-Bogoliubov (HFB) approximation. The parametrization D1M of the Gogny energy density functional (EDF) was used at the mean-field level to obtain the deformation energy surfaces for the considered nuclei in terms of the quadrupole deformations (β ,γ ). In addition to the energy surfaces, both single-particle energies and occupation probabilities were used as a microscopic input for building the IBFM Hamiltonian. Only three strength parameters for the particle-boson-core coupling are fitted to experimental spectra. The IBFM Hamiltonian is then used to compute the energy spectra and electromagnetic transition rates for selected odd-mass Eu and Sm nuclei as well as for 195Pt and 195Au. A reasonable agreement with the available experimental data is obtained for the considered odd-mass nuclei.
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.
Domain wall fermions and the η-invariant
NASA Astrophysics Data System (ADS)
Kaplan, David B.; Schmaltz, Martin
1996-02-01
We extend work by Callan and Harvey and show how the phase of the chiral fermion determinant in four dimensions is reproduced by zero modes bound to a domain wall in five dimensions. The analysis could shed light on the applicability of zero mode fermions and the vacuum overlap formulation of Narayanan and Neuberger for chiral gauge theories on the lattice.
SU(2) and SU(3) chiral perturbation theory analyses on baryon masses in 2+1 flavor lattice QCD
Ishikawa, K.-I.; Okawa, M.; Ishizuka, N.; Kuramashi, Y.; Taniguchi, Y.; Ukawa, A.; Yoshie, T.; Izubuchi, T.; Kadoh, D.; Namekawa, Y.; Ukita, N.; Kanaya, K.
2009-09-01
We investigate the quark mass dependence of baryon masses in 2+1 flavor lattice QCD using SU(3) heavy baryon chiral perturbation theory up to one-loop order. The baryon mass data used for the analyses are obtained for the degenerate up-down quark mass of 3 to 24 MeV and two choices of the strange quark mass around the physical value. We find that the SU(3) chiral expansion fails to describe both the octet and the decuplet baryon data if phenomenological values are employed for the meson-baryon couplings. The SU(2) case is also examined for the nucleon. We observe that higher order terms are controlled only around the physical point. We also evaluate finite size effects using SU(3) heavy baryon chiral perturbation theory, finding small values of order 1% even at the physical point.
NASA Astrophysics Data System (ADS)
Marino, Eduardo
The electron, discovered by Thomson by the end of the nineteenth century, was the first experimentally observed particle. The Weyl fermion, though theoretically predicted since a long time, was observed in a condensed matter environment in an experiment reported only a few weeks ago. Is there any linking thread connecting the first and the last observed fermion (quasi)particles? The answer is positive. By generalizing the method known as bosonization, the first time in its full complete form, for a spacetime with 3+1 dimensions, we are able to show that both electrons and Weyl fermions can be expressed in terms of the same boson field, namely the Kalb-Ramond anti-symmetric tensor gauge field. The bosonized form of the Weyl chiral currents lead to the angle-dependent magneto-conductance behavior observed in these systems.
Flavor and chiral oscillations with Dirac wave packets
Bernardini, A.E.; Leo, S. de
2005-04-01
We report about recent results on Dirac wave packets in the treatment of neutrino flavor oscillation where the initial localization of a spinor state implies an interference between positive and negative energy components of mass-eigenstate wave packets. A satisfactory description of fermionic particles requires the use of the Dirac equation as evolution equation for the mass eigenstates. In this context, a new flavor conversion formula can be obtained when the effects of chiral oscillation are taken into account. Our study leads to the conclusion that the fermionic nature of the particles, where chiral oscillations and the interference between positive and negative frequency components of mass-eigenstate wave packets are implicitly assumed, modifies the standard oscillation probability. Nevertheless, for ultrarelativistic particles and sharply peaked momentum distributions, we can analytically demonstrate that these modifications introduce correction factors proportional to m{sub 1,2}{sup 2}/p{sub 0}{sup 2} which are practically undetectable by any experimental analysis.
6d Dirac fermion on a rectangle; scrutinizing boundary conditions, mode functions and spectrum
NASA Astrophysics Data System (ADS)
Fujimoto, Yukihiro; Hasegawa, Kouhei; Nishiwaki, Kenji; Sakamoto, Makoto; Tatsumi, Kentaro
2017-09-01
We classify possible boundary conditions of a 6d Dirac fermion Ψ on a rectangle under the requirement that the 4d Lorentz structure is maintained, and derive the profiles and spectrum of the zero modes and nonzero KK modes under the two specific boundary conditions, (i) 4d-chirality positive components being zero at the boundaries and (ii) internal chirality positive components being zero at the boundaries. In the case of (i), twofold degenerated chiral zero modes appear which are localized towards specific directions of the rectangle pointed by an angle parameter θ. This leads to an implication for a new direction of pursuing the origin of three generations in the matter fields of the standard model, even though triple-degenerated zero modes are not realized in the six dimensions. When such 6d fermions couple with a 6d scalar with a vacuum expectation value, θ contributes to a mass matrix of zero-mode fermions consisting of Yukawa interactions. The emergence of the angle parameter θ originates from a rotational symmetry in the degenerated chiral zero modes on the rectangle extra dimensions since they do not feel the boundaries. In the case of (ii), this rotational symmetry is promoted to the two-dimensional conformal symmetry though no chiral massless zero mode appears. We also discuss the correspondence between our model on a rectangle and orbifold models in some details.
Majorana fermions in vortex lattices
NASA Astrophysics Data System (ADS)
Biswas, Rudro
2013-03-01
We consider Majorana fermions tunneling between vortices, within an array of such vortices in a 2D chiral p-wave superconductor. We calculate that the tunneling amplitude for Majorana fermions in a pair of vortices is proportional to the sine of half the difference between the global order parameter phases at the two vortices. Using this result we study tight-binding models of Majorana fermions in vortices arranged in a triangular or square lattice. In both cases we find that this phase-tunneling relationship leads to the creation of superlattices where the Majorana fermions form macroscopically degenerate `flat' bands at zero energy, in addition to other dispersive bands. This finding suggests that in vortex arrays tunneling processes do not change the energies of a finite fraction of Majorana fermions and hence brighten the prospects of topological quantum computing with a large number of Majorana states.
Cartography with Locating Fermions in Extra Dimensions at Future Lepton Colliders
Rizzo, Thomas G.
2001-01-24
In the model of Arkani-Hamed and Schmaltz the various chiral fermions of the Standard Model(SM) are localized at different points on a thick wall which forms an extra dimension. Such a scenario provides a way of understanding the absence of proton decay and the fermion mass hierarchy in models with extra dimensions. In this paper we explore the capability of future lepton colliders to determine the location of these fermions in the extra dimension through precision measurements of conventional scattering processes both below and on top of the lowest lying Kaluza-Klein gauge boson resonance. We show that for some classes of models the locations of these fermions can be very precisely determined while in others only their relative positions can be well measured.
Effect of Fermion Velocity on Phase Structure of QED3
NASA Astrophysics Data System (ADS)
Li, Jian-Feng; Feng, Hong-Tao; Zong, Hong-Shi
2016-11-01
Dynamical chiral symmetry breaking (DCSB) in thermal QED3 with fermion velocity is studied in the framework of Dyson-Schwinger equations. By adopting instantaneous approximation and neglecting the transverse component of gauge boson propagator at finite temperature, we numerically solve the fermion self-energy equation in the rainbow approximation. It is found that both DCSB and fermion chiral condensate are suppressed by fermion velocity. Moreover, the critical temperature decreases as fermion velocity increases. Supported in part by the National Natural Science Foundation of China under Grant No. 11535005 and the Natural Science Foundation of Jiangsu Province under Grant No. BK20130387
Baryon mass splittings and strong CP violation in SU(3) chiral perturbation theory
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(m2q). 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 up to the ordermore » 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
Weiß, Jennifer A; Mohr, Stefan; Schmid, Martin G
2015-03-01
New recreational drugs such as amphetamine-, cathinone, and benzofury derivatives gained high popularity on the drug market in recent years. They can be purchased via the Internet from different providers and online portals. Most of these compounds are chiral, which makes the development of chiral separation methods necessary. Besides this, it is useful to find out if the compounds were sold as racemic mixtures. Also, it is important to check whether the new psychoactive compounds contain further ingredients or impurities. The aim of this research was the continuation of the application of a method for indirect chiral separation of 24 new psychoactive compounds recently purchased via the Internet. After derivatization with the chiral derivatization reagent trifluoroacetyl-L-prolyl chloride, chromatographic separation of diastereomers was achieved using a 30 m HP5-MS capillary column. As carrier gas, helium was used with a constant flow of 1.0 ml/min. Three different column temperature programs were tested. Under optimum conditions 13 out of 24 compounds were successfully resolved into their enantiomers obtaining Rs values up to 7.0. The use of a single quadrupole mass spectrometer as the detector allowed the identification of the compounds in multicomponent samples.
Yu, Jimei; Li, Xin; Zhou, Jiezhao; Xie, Xiangyang; Chen, Meiling; He, Xinhua; Yang, Yang; Zhang, Youzhi; Zheng, Aiping; Mei, Xingguo; Li, Ying
2017-05-01
Ammuxetine (AMT), a novel chiral antidepressant candidate compound, exhibits better antidepression effects than duloxetine in different animal models. In this article, a chiral derivatization method, combined with online solid phase extraction (online SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), was developed for the chiral separation of AMT enantiomers after administration of racemic AMT to dogs. The derivatization reaction employed 2,3,4,6-tetra-O-acetyl-b-glucopyr-anosyl isothiocyanate (GITC) as a precolumn chiral derivatization reagent. A SPE column Retain PEP Javelin (10 × 2.1 mm) was used to remove proteins and other impurities in plasma samples. The enantiomeric derivatives were separated on a ZORBAX SB-C18 column (50 × 2.1 mm × 3.5 μm) with an isocratic elution procedure. The selected multiple reaction monitoring mode of the positive ion was performed and the parent to the product transitions m/z 681.0/543.1 and m/z 687.4/543.1 were used to measure the derivatives of AMT and duloxetine (internal standard) with electrospray ionization. The method was validated in terms of specificity, linearity, sensitivity, precision, accuracy, matrix effect, and stability. The method was applied to a pharmacokinetics study of AMT racemate in dogs. The results suggested that the pharmacokinetic of AMT enantiomers might be stereoselective in dogs. © 2017 Wiley Periodicals, Inc.
Low energy chiral lagrangian parameters for scalar and pseudoscalar mesons
NASA Astrophysics Data System (ADS)
Bardeen, W.; Eichten, E.; Thacker, H.
2003-05-01
We present results of a high-statistics study of scalar and pseudoscalar meson propagators in quenched QCD at two values of lattice spacing,β = 5.7 and 5.9, with clover-improved Wilson fermions. The study of the chiral limit is facilitated by the pole-shifting ansatz of the modified quenched approximation. Pseudoscalar masses and decay constants are determined as a function of quark mass and quenched chiral log effects are estimated. A study of the flavor singlet ν' hairpin diagram yields a precise determination of the ν' mass insertion. The corresponding value of the quenched chiral log parameter b is compared with the observed QCL effects. Removal of QCL effects from the scalar propagator allows a determination of the mass of the lowest lying isovector scalar qq meson.
BLUM,T.; SONI,A.
2007-03-15
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 remarkable 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.
Determination of the chiral condensate from QCD Dirac spectrum on the lattice
Fukaya, H.; Onogi, T.; Aoki, S.; Chiu, T. W.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Noaki, J.
2011-04-01
We calculate the chiral condensate of QCD with 2, 2+1, and 3 flavors of sea quarks. Lattice QCD simulations are performed employing dynamical overlap fermions with up- and down-quark masses covering a range between 3 and 100 MeV. On L{approx}1.8-1.9 fm lattices at a lattice spacing {approx}0.11 fm, we calculate the eigenvalue spectrum of the overlap-Dirac operator. By matching the lattice data with the analytical prediction from chiral perturbation theory at the next-to-leading order, the chiral condensate in the massless limit of up and down quarks is determined.
Staggered heavy baryon chiral perturbation theory
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}}{sup 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.
Catalysis of dynamical chiral symmetry breaking by chiral chemical potential
NASA Astrophysics Data System (ADS)
Braguta, V. V.; Kotov, A. Yu.
2016-05-01
In this paper, we study the properties of media with chiral imbalance parametrized by chiral chemical potential. It is shown that depending on the strength of interaction between constituents in the media the chiral chemical potential either creates or enhances dynamical chiral symmetry breaking. Thus, the chiral chemical potential plays the role of the catalyst of dynamical chiral symmetry breaking. Physically, this effect results from the appearance of the Fermi surface and additional fermion states on this surface, which take part in dynamical chiral symmetry breaking. An interesting conclusion which can be drawn is that at sufficiently small temperature chiral plasma is unstable with respect to condensation of Cooper pairs and dynamical chiral symmetry breaking even for vanishingly small interactions between constituents.
Chiral symmetry and chiral-symmetry breaking
Peskin, M.E.
1982-12-01
These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed. (WHK)
Adjoint QCD on ℝ3 × S 1 with twisted fermionic boundary conditions
NASA Astrophysics Data System (ADS)
Misumi, Tatsuhiro; Kanazawa, Takuya
2014-06-01
We investigate QCD with adjoint Dirac fermions on ℝ3 × S 1 with generic boundary conditions for fermions along S 1. By means of perturbation theory, semiclassical methods and a chiral effective model, we elucidate a rich phase structure in the space spanned by the S 1 compactification scale L, twisted fermionic boundary condition ϕ and the fermion mass m. We found various phases with or without chiral and center symmetry breaking, separated by first- and second-order phase transitions, which in specific limits ( ϕ = 0, ϕ = π, L → 0 and m → ∞) reproduce known results in the literature. In the center- symmetric phase at small L, we show that Ünsal's bion-induced confinement mechanism is at work but is substantially weakened at ϕ = 0 by a linear potential between monopoles. Through an analytic and numerical study of the PNJL model, we show that the order parameters for center and chiral symmetries (i.e., Polyakov loop and chiral condensate) are strongly intertwined at ϕ = 0. Due to this correlation, a deconfined phase can intervene between a weak-coupling center-symmetric phase at small L and a strong-coupling one at large L. Whether this happens or not depends on the ratio of the dynamical fermion mass to the energy scale of the Yang-Mills theory. Implication of this possibility for resurgence in gauge theories is briefly discussed. In an appendix, we study the index of the adjoint Dirac operator on ℝ3 × S 1 with twisted boundary conditions, which is important for semiclassical analysis of monopoles.
Ultracold Fermions in a Cavity-Induced Artificial Magnetic Field
NASA Astrophysics Data System (ADS)
Kollath, Corinna; Sheikhan, Ameneh; Wolff, Stefan; Brennecke, Ferdinand
2016-02-01
We propose how a fermionic quantum gas confined to an optical lattice and coupled to an optical cavity can self-organize into a state where the spontaneously emerging cavity field amplitude induces an artificial magnetic field. The fermions form either a chiral insulator or a chiral liquid carrying chiral currents. The feedback mechanism via the dynamical cavity field enables robust and fast switching in time of the chiral phases, and the cavity output can be employed for a direct nondestructive measurement of the chiral current.
Quantum gravity and Standard-Model-like fermions
NASA Astrophysics Data System (ADS)
Eichhorn, Astrid; Lippoldt, Stefan
2017-04-01
We discover that chiral symmetry does not act as an infrared attractor of the renormalization group flow under the impact of quantum gravity fluctuations. Thus, observationally viable quantum gravity models must respect chiral symmetry. In our truncation, asymptotically safe gravity does, as a chiral fixed point exists. A second non-chiral fixed point with massive fermions provides a template for models with dark matter. This fixed point disappears for more than 10 fermions, suggesting that an asymptotically safe ultraviolet completion for the standard model plus gravity enforces chiral symmetry.
Alexandru, Andrei; Horváth, Ivan
2016-01-22
The validity of recently proposed equivalence between valence spontaneous chiral symmetry breaking (vSChSB) and chiral polarization of low energy Dirac spectrum (ChP) in SU(3) gauge theory, is examined for the case of twelve mass–degenerate fundamental quark flavors. We find that the vSChSB–ChP correspondence holds for regularized systems studied. Moreover, our results suggest that vSChSB occurs in two qualitatively different circumstances: there is a quark mass m{sub c} such that for m > m{sub c} the mode condensing Dirac spectrum exhibits standard monotonically increasing density, while for m{sub ch} < m < m{sub c} the peak around zero separates from the bulk of the spectrum, with density showing a pronounced depletion at intermediate scales. Valence chiral symmetry restoration may occur at yet smaller masses m < m{sub ch}, but this has not yet been seen by overlap valence probe, leaving the m{sub ch} = 0 possibility open. The latter option could place massless N{sub f}=12 theory outside of conformal window. Anomalous behavior of overlap Dirac spectrum for m{sub ch} < m < m{sub c} is qualitatively similar to one observed previously in zero and few–flavor theories as an effect of thermal agitation.
Covariant nonlocal chiral quark models with separable interactions
Dumm, D. Gomez; Grunfeld, A. G.; Scoccola, N. N.
2006-09-01
We present a comparative analysis of chiral quark models which include nonlocal covariant four-fermion couplings. We consider two alternative ways of introducing the nonlocality, as well as various shapes for the momentum-dependent form factors governing the effective interactions. In all cases we study the behavior of model parameters and analyze numerical results for constituent quark masses and quark propagator poles. Advantages of these covariant nonlocal schemes over instantaneous nonlocal schemes and the standard NJL model are pointed out.
NASA Astrophysics Data System (ADS)
Girdhar, Aarti; Dahiya, Harleen; Randhawa, Monika
2015-08-01
The magnetic moments of JP=3/2+ decuplet baryons have been calculated in the chiral constituent quark model (χ CQM ) with explicit results for the contribution coming from the valence quark polarizations, sea quark polarizations, and their orbital angular momentum. Since the JP=3/2+ decuplet baryons have short lifetimes, the experimental information about them is limited. The χ CQM has important implications for chiral symmetry breaking as well as SU(3) symmetry breaking since it works in the region between the QCD confinement scale and the chiral symmetry breaking scale. The predictions in the model not only give a satisfactory fit when compared with the experimental data but also show improvement over the other models. The effect of the confinement on quark masses has also been discussed in detail and the results of χ CQM are found to improve further with the inclusion of effective quark masses.
Electrodynamics of chiral matter
NASA Astrophysics Data System (ADS)
Qiu, Zebin; Cao, Gaoqing; Huang, Xu-Guang
2017-02-01
Many-body systems with chiral fermions can exhibit novel transport phenomena that violate parity and time-reversal symmetries, such as the chiral magnetic effect, the anomalous Hall effect, and the anomalous generation of charge. Based on the Maxwell-Chern-Simons electrodynamics, we examine some electromagnetic and optical properties of such systems including the electrostatics, the magnetostatics, the propagation of electromagnetic waves, the novel optical effects, etc.
Nucleon sigma term and strange quark content from lattice QCD with exact chiral symmetry
Ohki, H.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Matsufuru, H.; Noaki, J.; Shintani, E.; Onogi, T.
2008-09-01
We calculate the nucleon sigma term in two-flavor lattice QCD utilizing the Feynman-Hellman theorem. Both sea and valence quarks are described by the overlap fermion formulation, which preserves exact chiral and flavor symmetries on the lattice. We analyze the lattice data for the nucleon mass using the analytical formulae derived from the baryon chiral perturbation theory. From the data at valence quark mass set different from sea quark mass, we may extract the sea quark contribution to the sigma term, which corresponds to the strange quark content. We find that the strange quark content is much smaller than the previous lattice calculations and phenomenological estimates.
Wang, Jiang; Jiang, Xiao-Xiao; Zhao, Wei; Hu, Jun; Guan, Qi-Yuan; Xu, Jing-Juan; Chen, Hong-Yuan
2017-08-15
The direct separation and analysis of chiral drugs in the complex matrix systems are meaningful and challenging. As the most common broad-spectrum antibiotic, levofloxacin has a strong antibacterial ability, but its enantiomer, dextrofloxacin can cause serious harm to human health. In this work, we reported a rapid on-line extraction/ionization device coupled with Electrospray Mass Spectrometry (ESI-MS) for chiral analysis of ofloxacin enantiomers in complex matrix of milk. Since ofloxacin is difficult to dissolve in water and most organic solvents, the procedure of separating ofloxacin in complex system is often complicated. Using the homemade apparatus, the sample pretreatment process was greatly simplified. Milk sample was directly injected and chiral ofloxacin in the sample was extracted at PTFE membrane for further ionization. It took less than 10s to finish all the procedures including sampling, extraction, reagents mixing, ionization and mass analysis. Utilizing reaction thermodynamics method, trimeric cluster ion [Ni(ΙΙ)(ref)2Ofloxacin-H](+) was formed and collisionally dissociated to get chiral resolution of levofloxacin and dextrofloxacin due to the different relative stabilities of the two diastereomeric clusters produced through the dissociation of Ni(ΙΙ) bound trimeric clusters. With the proposed method, qualitative and quantitative chiral analysis of ofloxacin in milk was successfully achieved in a simple and fast way. Copyright © 2017 Elsevier B.V. All rights reserved.
Chiral logarithms in quenched QCD
Y. Chen; S. J. Dong; T. Draper; I. Horvath; F. X. Lee; K. F. Liu; N. Mathur; and J. B. Zhang
2004-08-01
The quenched chiral logarithms are examined on a 163x28 lattice with Iwasaki gauge action and overlap fermions. The pion decay constant fpi is used to set the lattice spacing, a = 0.200(3) fm. With pion mass as low as {approx}180 MeV, we see the quenched chiral logarithms clearly in mpi2/m and fP, the pseudoscalar decay constant. The authors analyze the data to determine how low the pion mass needs to be in order for the quenched one-loop chiral perturbation theory (chiPT) to apply. With the constrained curve-fitting method, they are able to extract the quenched chiral logarithmic parameter delta together with other low-energy parameters. Only for mpi<=300 MeV do we obtain a consistent and stable fit with a constant delta which they determine to be 0.24(3)(4) (at the chiral scale Lambdachi = 0.8 GeV). By comparing to the 123x28 lattice, they estimate the finite volume effect to be about 2.7% for the smallest pion mass. They also fitted the pion mass to the form for the re-summed cactus diagrams and found that its applicable region is extended farther than the range for the one-loop formula, perhaps up to mpi {approx}500-600 MeV. The scale independent delta is determined to be 0.20(3) in this case. The authors study the quenched non-analytic terms in the nucleon mass and find that the coefficient C1/2 in the nucleon mass is consistent with the prediction of one-loop chiPT. They also obtain the low energy constant L5 from fpi. They conclude from this study that it is imperative to cover only the range of data with the pion mass less than {approx}300 MeV in order to examine the chiral behavior of the hadron masses and decay constants in quenched QCD and match them with quenched one-loop chiPT.
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
Aaltonen, Timo Antero
2016-06-20
A search for a Higgs boson with suppressed couplings to fermions, $h_f$, 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.
Convergence of the Chiral Expansion in Two-Flavor Lattice QCD
Noaki, J.; Matsufuru, H.; Shintani, E.; Aoki, S.; Chiu, T. W.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Hsieh, T. H.; Onogi, T.
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 {approx}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{sub 3} and l{sub 4} as well as the pion decay constant, the chiral condensate, and the average up and down quark mass.
Lattice simulations with eight flavors of domain wall fermions in SU(3) gauge theory
NASA Astrophysics Data System (ADS)
Appelquist, T.; Brower, R. C.; Fleming, G. T.; Kiskis, J.; Lin, M. F.; Neil, E. T.; Osborn, J. C.; Rebbi, C.; Rinaldi, E.; Schaich, D.; Schroeder, C.; Syritsyn, S.; Voronov, G.; Vranas, P.; Weinberg, E.; Witzel, O.; Lattice Strong Dynamics LSD Collaboration
2014-12-01
We study an SU(3) gauge theory with Nf=8 degenerate flavors of light fermions in the fundamental representation. Using the domain wall fermion formulation, we investigate the light hadron spectrum, chiral condensate ⟨ψ ¯ ψ ⟩ and electroweak S parameter. We consider a range of light fermion masses on two lattice volumes at a single gauge coupling chosen so that IR scales approximately match those from our previous studies of the two- and six-flavor systems. Our results for the Nf=8 spectrum suggest spontaneous chiral symmetry breaking, though fits to the fermion mass dependence of spectral quantities do not strongly disfavor the hypothesis of mass-deformed infrared conformality. Compared to Nf=2 we observe a significant enhancement of ⟨ψ ¯ψ ⟩ relative to the symmetry breaking scale F , similar to the situation for Nf=6 . The reduction of the S parameter, related to parity doubling in the vector and axial-vector channels, is also comparable to our six-flavor results.
Phenomenology of strongly coupled chiral gauge theories
Bai, Yang; Berger, Joshua; Osborne, James; Stefanek, Ben A.
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 such 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.
Lifetime measurements in mass regions A=100 and A=130 as a test for chirality in nuclear systems
NASA Astrophysics Data System (ADS)
Tonev, D.; Yavahchova, M. S.; de Angelis, G.; Brant, S.; Frauendorf, S.; Petkov, P.; Dewald, A.; Zhong, Q.; Curien, D.; Goutev, N.; Bhowmik, R. K.; Singh, R. P.; Muralithar, S.; Madhavan, N.; Kumar, R.; Raju, M. Kumar; Kaur, J.; Mahanto, G.; Singh, A.; Kaur, N.; Garg, R.; Sukla, A.; Geleva, E.; Marinov, Ts. K.
2016-01-01
Two odd-odd nuclei from the A ~ 100 and A ~ 130 regions, namely 102Rh and 134Pr have been studied in search for chiral doublet bands via 94Zr(11B,3n)102Rh and 119Sn(19F,4n)134Pr reactions, respectively. Two nearly degenerate bands built on the πg9/2 ⊗ vh11/2 configuration have been identified in 102Rh and on the πg11/2 ⊗ vh11/2 configuration for 134Pr. Lifetimes of excited nuclear states were measured using Dopplershift attenuation method and recoil distance Doppler-shift method. The deexciting gamma rays were registered by the Indian National Gamma Array for 102Rh and using the EUROBALL IV detector array with an inner Bismuth Germanate (BGO) ball for 134Pr, respectively. Polarization and angular correlation measurements have been performed to establish the spin and parity assignments for these bands. The derived reduced transition probabilities are compared to the predicitons of the two quasiparticles + triaxial rotor and interacting boson fermion-fermion models.
Lu, W; Cole, R B
1998-08-28
On-line capillary electrophoresis-electrospray ionization mass spectrometry (CE-ESI-MS) has been employed for the determination of racemic mixtures of the chiral drugs, terbutaline, ketamine, and propranolol. Separation of the different chiral forms has been achieved by introducing cyclodextrins (CDs), which act as chiral selectors, into the CE operating electrolytes. Cyclodextrins function as chiral selectors in CE because of their ability to form host-guest complexes (inclusion complexes) of varying stability with an array of chiral drugs and other compounds. Derivatized forms of beta-CD (i.e., dimethyl-beta-cyclodextrin and hydroxypropyl-beta-cyclodextrin) were used in this study due to their higher solubilities in the aqueous methanolic operating electrolyte than native beta-CD. Addition of minor quantities of methanol to the aqueous-based CE operating electrolytes improved the stability of electrospray ionization conditions and further enhanced CE resolution of the enantiomeric pairs relative to purely aqueous systems. Introduction of the CDs into the CE operating electrolytes caused suppression of analyte signals in ESI-MS, and the dependence of analyte signal intensities on the solution concentrations of the derivatized beta-CDs was examined. Under optimized conditions, the different enantiomeric forms of the compounds under investigation were successfully separated and detected by CE-ESI-MS.
Octet baryon masses and sigma terms from an SU(3) chiral extrapolation
Young, Ross; Thomas, Anthony
2009-01-01
We analyze the consequences of the remarkable new results for octet baryon masses calculated in 2+1- avour lattice QCD using a low-order expansion about the SU(3) chiral limit. We demonstrate that, even though the simulation results are clearly beyond the power-counting regime, the description of the lattice results by a low-order expansion can be significantly improved by allowing the regularisation scale of the effective field theory to be determined by the lattice data itself. The model dependence of our analysis is demonstrated to be small compared with the present statistical precision. In addition to the extrapolation of the absolute values of the baryon masses, this analysis provides a method to solve the difficult problem of fine-tuning the strange-quark mass. We also report a determination of the sigma terms for all of the octet baryons, including an accurate value of the pion-nucleon sigma term and the first determination of the strangeness sigma term based on 2+1-flavour l
The kaon B-parameter from 2+1-flavor Domain-Wall-Fermion lattices
Cohen, Saul; Anthony, David
2007-11-01
We present the final results of the RBC/UKQCD calculation of the kaon B-parameter on 2+1- flavor domain-wall fermion lattices at a^?1 = 1.73(3) GeV. We simulate on two lattice volumes of about (1.8 fm)^3 and (2.7 fm)^3, with the lightest valence pion about on the large volume approximately 250 MeV. The light pion masses and our chiral fermion action allow us to compare lattice data to NLO chiral perturbation theory, facilitating a controlled extrapolation to the physical point. We present a final result including nonperturbative renormalization and detailed systematic errors. Our final result is BMS/K (2 GeV) = 0.524(10)(28).
Arakawa; Kobayashi; Ama
2000-09-01
The chiral recognition of metal complexes by a quick and sensitive mass spectrometric analysis was investigated. The principle is introduction of an external chiral standard compound and detection of the differential association with two optical isomers. Using electrospray ionization mass spectrometry we detected weak intermolecular association between the external chiral anion bis(mu-L-, D-tartrato)-diantimonate(III), [Sb2(L-, D-tart)2]2- and isomeric bis(L-alaninate) ethylenediamine cobalt(III) complex ions, [Co(L-ala)2(en)]+ in acetonitrile/water solution. The difference in the association with optical isomers of the Co complex was measured. The results were interpreted based on a model of intermolecular interaction involving hydrogen bonding. The prospects of the mass spectrometry method for chiral recognition using the external chiral negative ion [Sb2(L-, D-tart)2]2- was discussed.
Hanhart, C; Peláez, J R; Ríos, G
2008-04-18
We use the one-loop chiral perturbation theory pipi-scattering amplitude and dispersion theory in the form of the inverse amplitude method to study the quark-mass dependence of the two lightest resonances of the strong interactions, the f(0)(600) (sigma) and the rho meson. As the main results, we find that the rhopipi coupling constant is almost quark mass independent and that the rho mass shows a smooth quark-mass dependence while that of the sigma shows a strong nonanalyticity. These findings are important for studies of the meson spectrum on the lattice.
Cloaking two-dimensional fermions
Lin, De-Hone
2011-09-15
A cloaking theory for a two-dimensional spin-(1/2) fermion is proposed. It is shown that the spinor of the two-dimensional fermion can be cloaked perfectly through controlling the fermion's energy and mass in a specific manner moving in an effective vector potential inside a cloaking shell. Different from the cloaking of three-dimensional fermions, the scaling function that determines the invisible region is uniquely determined by a nonlinear equation. It is also shown that the efficiency of the cloaking shell is unaltered under the Aharonov-Bohm effect.
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.
Mass limits for the chiral color symmetry G‧-boson from LHC dijet data
NASA Astrophysics Data System (ADS)
Frolov, I. V.; Smirnov, A. D.
2016-07-01
The contributions of G‧-boson predicted by the chiral color symmetry of quarks to the differential dijet cross-sections in pp-collisions at the large hadron collider (LHC) are calculated and analyzed in dependence on two free parameters of the model, the G‧ mass mG‧ and mixing angle 𝜃G. The exclusion and consistency mG‧- 𝜃G regions imposed by the ATLAS and CMS data on dijet cross-sections are found. Using the CT10 (MSTW2008) parton distribution function (PDF) set we show that the G‧-boson for 𝜃G = 45∘, i.e. the axigluon, with the masses mG‧ < 2.3(2.6) TeV and mG‧ < 3.35(3.25) TeV is excluded at the probability level of 95% by the ATLAS and CMS dijet data, respectively. For the other values of 𝜃G the exclusion limits are more stringent. The mG‧- 𝜃G regions consistent with these data at CL = 68% and CL = 90% are also found.
Drake, Samantha J; Morrison, Calum; Smith, Frank
2011-09-01
Methylamphetamine, ephedrine, and pseudoephedrine were derivatized using trifluoroacetic anhydride and enantiomers of each were analyzed using gas chromatography coupled to mass spectrometry (GC/MS) fitted with a γ-cyclodextrin (Chiraldex™ G-PN) chiral column. A temperature-programmed method was developed and optimized and the results compared with those obtained using a previously published isothermal GC method applied to GC/MS analysis. Trifluoroacetylated 3-(trifluoromethyl)phenethylamine hydrochloride was used as an internal standard, and mass fragmentation patterns are proposed for all derivatives analyzed. Qualitative validation of the optimized chromatographic conditions was completed in accordance with the guidelines published by the United Nations Office on Drugs and Crime (UNODC). Under conditions of repeatability and reproducibility, the method gave relative retention times with a relative standard deviation of less than 0.02% for all six analytes of interest. This surpasses the UNODC's acceptance criteria of 2% for validation of qualitative precision. Ephedrine and pseudoephedrine are common precursors in the clandestine manufacture of methylamphetamine. Seizures of illicit methylamphetamine therefore often contain mixtures of these optically active compounds. The simultaneous enantioseparation of these compounds to produce a profile would provide valuable information to law enforcement agencies regarding the provenance of a methylamphetamine seizure.
NASA Astrophysics Data System (ADS)
Bradlyn, Barry; Cano, Jennifer; Wang, Zhijun; Hirschberger, Max; Ong, N. Phuan; Bernevig, B. Andrei
Materials with intrinsic Weyl points should present exotic magnetotransport phenomena due to spectral flow between Weyl nodes of opposite chirality - the so-called ``chiral anomaly''. However, to date, the most definitive transport data showing the presence of a chiral anomaly comes from Dirac (not Weyl) materials. These semimetals develop Weyl fermions only in the presence of an externally applied magnetic field, when the four-fold degeneracy is lifted. In this talk we examine Berry phase effects on transport due to the emergence of these field-induced Weyl point and (in some cases) line nodes. We pay particular attention to the differences between intrinsic and field-induced Weyl fermions, from the point of view of kinetic theory. Finally, we apply our analysis to a particular material relevant to current experiments performed at Princeton.
FERMION MASSES AND NEUTRINO OSCILLATIONS IN SO(10) X SU(2)F*
CHEN, M-C.; MAHANTHAPPA, K.T.
2004-06-17
We present in this talk a model based on SO(10) x SU(2){sub F} having symmetric mass textures with 5 zeros constructed by us recently. The symmetric mass textures arising from the left-right symmetry breaking chain of SO(10) give rise to good predictions for the masses, mixing angles and CP violation measures in the quark and lepton sectors (including the neutrinos), all in agreement with the most up-to-date experimental data within 1 {sigma}. Various lepton flavor violating decays in our model are also investigated. Unlike in models with lop-sided textures, our prediction for the decay rate of {mu} + e{gamma} is much suppressed and yet it is large enough to be probed by the next generation of experiments. The observed baryonic asymmetry in the Universe can be accommodated in our model utilizing soft leptogenesis.
Universal SU(2/1) and the Higgs and fermion masses
Ne`eman, Y.
1992-12-31
We review the SU(2/1) internal supersymmetry suggested by D. Fairlie and the author in 1979. The initial apparent difficulties were resolved when, with J. Thierry-Mieg, we understood that the gauging of a supergroup implies taking the usual Yang-Mills-like Principal (Double) Fibre Bundle as a ``scaffold`` and using its Grassmann algebra as parameter manifold for the supergauge. SU(2/1) Universality fixes the masses of the Higgs scalar field and the ``top`` quark around 100--200 GeV, in the same region as the W and Z masses. A ``unified``` supergauge, enclosing SU(3)colour x SU(2) x U(l), predicts a fourth lepton generation in which the neutrino mass is of the same order.
Fermion fractionalization to Majorana fermions in a dimerized Kitaev superconductor
NASA Astrophysics Data System (ADS)
Wakatsuki, Ryohei; Ezawa, Motohiko; Tanaka, Yukio; Nagaosa, Naoto
2014-07-01
We study theoretically a one-dimensional dimerized Kitaev superconductor model which belongs to BDI class with time-reversal, particle-hole, and chiral symmetries. There are two sources of the particle-hole symmetry, i.e., the sublattice symmetry and superconductivity. Accordingly, we define two types of topological numbers with respect to the chiral indices of normal and Majorana fermions, which offers an ideal laboratory to examine the interference between the two different physics within the same symmetry class. Phase diagram, zero-energy bound states, and conductance at normal metal/superconductor junction of this model are unveiled from this viewpoint. Especially, the electron fractionalization to the Majorana fermions showing the splitting of the local density of states is realized at the soliton of the dimerization in this model.
Fermion Fractionalization to Majorana Fermions in Dimerized Kitaev Superconductor
NASA Astrophysics Data System (ADS)
Wakatsuki, Ryohei; Ezawa, Motohiko; Tanaka, Yukio; Nagaosa, Naoto
2015-03-01
We study theoretically a one-dimensional dimerized Kitaev superconductor model which belongs to BDI class with time-reversal, particle-hole, and chiral symmetries. There are two sources of the particle-hole symmetry, i.e., the sublattice symmetry and superconductivity. Accordingly, we define two types of topological numbers with respect to the chiral indices of normal and Majorana fermions, which offers an ideal laboratory to examine the interference between the two different physics within the same symmetry class. Phase diagram, zero-energy bound states, and conductance at normal metal/superconductor junction of this model are unveiled from this viewpoint. Especially, the electron fractionalization to the Majorana fermions showing the splitting of the local density of states is realized at the soliton of the dimerization in this model.
NASA Astrophysics Data System (ADS)
Giusti, D.; Lubicz, V.; Tarantino, C.; Martinelli, G.; Sanfilippo, F.; Simula, S.; Tantalo, N.; RM123 Collaboration
2017-06-01
We present a lattice computation of the isospin-breaking corrections to pseudoscalar meson masses using the gauge configurations produced by the European Twisted Mass Collaboration with Nf=2 +1 +1 dynamical quarks at three values of the lattice spacing (a ≃0.062 , 0.082, and 0.089 fm) with pion masses in the range Mπ≃210 - 450 MeV . The strange and charm quark masses are tuned at their physical values. We adopt the RM123 method based on the combined expansion of the path integral in powers of the d - and u -quark mass difference (m^d-m^u) and of the electromagnetic coupling αe m. Within the quenched QED approximation, which neglects the effects of the sea-quark charges, and after the extrapolations to the physical pion mass and to the continuum and infinite volume limits, we provide results for the pion, kaon, and (for the first time) charmed-meson mass splittings, for the prescription-dependent parameters ɛπ0, ɛγ(M S ¯ ,2 GeV ) , ɛK0(M S ¯ ,2 GeV ) , related to the violations of the Dashen's theorem, and for the light quark mass difference (m^ d-m^ u)(M S ¯ ,2 GeV ) .
Universal seesaw mechanisms for quark-lepton mass spectrum
NASA Astrophysics Data System (ADS)
Sogami, Ikuo S.; Shinohara, Tadatomi
1993-04-01
Problems of fermion mass hierarchies and generation mixings are investigated through universal seesaw mechanisms (USM's) in an extension of the standard model with a left-right-symmetric gauge group SU(3)c×SU(2)L×SU(2)R×U(1)y. Electroweak Higgs doublets and singlets induce USM's between ordinary fermion multiplets and exotic electroweak singlets of fermions. The USM's work singly in the charged-fermion sectors to suppress their masses below the electroweak mass scale, and doubly in the neutral-fermion sector to make neutrinos superlight. The wide gap between vanishingly small neutrino masses and the 100 GeV scale of the top-quark mass is explained by multiple USM suppressions without presuming a huge Majorana mass. A global chiral U(1)A symmetry is introduced so as to circumvent the strong CP violation, to distinguish generations, and to restrict the pattern of the Yukawa interactions. Three kinds of electroweak Higgs singlets bring about USM's and cause the generation mixing leading to a realistic variety in each charge sector of the fermion mass spectrum. A fourth Higgs singlet with the largest vacuum expectation value is introduced to make the neutrino masses tiny and to make the axion invisible. By assigning chiral charges to make effective mass matrices of all fermion sectors of the extended Fritzsch type, characteristics of the mass spectra of charged fermions and the quark mixing matrix are described without introducing unnatural hierarchies in the Yukawa coupling constants. Neutrinos have a spectrum comprising doubly degenerate states with a smaller mass and a singlet state with a larger mass. The vacuum mixing angle takes a small value which is favorable for explaining both the new results of the GALLEX Collaboration and the data of the Homestake and Kamiokande experiments.
Prior, A; Moldovan, R C; Crommen, J; Servais, A C; Fillet, M; de Jong, G J; Somsen, G W
2016-10-12
The sensitivity of coupled enantioselective capillary electrophoresis-mass spectrometry (CE-MS) of amino acids (AAs) is often hampered by the chiral selectors in the background electrolyte (BGE). A new method is presented in which the use of a chiral selector is circumvented by employing (+)-1-(9-fluorenyl)ethyl chloroformate (FLEC) as chiral AA derivatizing agent and ammonium perfluorooctanoate (APFO) as a volatile pseudostationary phase for separation of the formed diastereomers. Efficient AA derivatization with FLEC was completed within 10 min. Infusion experiments showed that the APFO concentration hardly affects the MS response of FLEC-AAs and presents significantly less ion suppression than equal concentrations of ammonium acetate. The effect of the pH and APFO concentration of the BGE and the capillary temperature were studied in order to achieve optimized enantioseparation. Optimization of CE-MS parameters, such as sheath-liquid composition and flow rate, ESI and MS settings was performed in order to prevent analyte fragmentation and achieve sensitive detection. Selective detection and quantification of 14 chiral proteinogenic AAs was achieved with chiral resolution between 1.2 and 8.6, and limits of detection ranging from 130 to 630 nM injected concentration. Aspartic acid and glutamic acid were detected, but not enantioseparated. The optimized method was applied to the analysis of chiral AAs in cerebrospinal fluid (CSF). Good linearity (R(2) > 0.99) and acceptable peak area and electrophoretic mobility repeatability (RSDs below 21% and 2.4%, respectively) were achieved for the chiral proteinogenic AAs, with sensitivity and chiral resolution mostly similar to obtained for standard solutions. Next to l-AAs, endogenous levels of d-serine and d-glutamine could be measured in CSF revealing enantiomeric ratios of 4.8%-8.0% and 0.34%-0.74%, respectively, and indicating the method's potential for the analysis of low concentrations of d-AAs in presence of
Quasiparticle Lifetime in Ultracold Fermionic Mixtures with Density and Mass Imbalance
NASA Astrophysics Data System (ADS)
Lan, Zhihao; Bruun, Georg M.; Lobo, Carlos
2013-10-01
We show that atomic Fermi mixtures with density and mass imbalance exhibit a rich diversity of scaling laws for the quasiparticle decay rate beyond the quadratic energy and temperature dependence of conventional Fermi liquids. For certain densities and mass ratios, the decay rate is linear, whereas in other cases, it exhibits a plateau. Remarkably, this plateau extends from the deeply degenerate to the high temperature classical regime of the light species. Many of these scaling laws are analogous to what is found in very different systems, including dirty metals, liquid metals, and high temperature plasmas. The Fermi mixtures can in this sense span a whole range of seemingly diverse and separate physical systems. Our results are derived in the weakly interacting limit, making them quantitatively reliable. The different regimes can be detected with radio-frequency spectroscopy.
Singlet-doublet fermionic dark matter, neutrino mass, and collider signatures
NASA Astrophysics Data System (ADS)
Bhattacharya, Subhaditya; Sahoo, Nirakar; Sahu, Narendra
2017-08-01
We propose a minimal extension of the standard model by including a scalar triplet with hypercharge 2 and two vectorlike leptons, one doublet and a singlet, to explain simultaneously the nonzero neutrino mass and dark matter (DM) content of the Universe. The DM emerges as a mixture of the neutral component of the vectorlike lepton doublet and singlet, being odd under a discrete Z2 symmetry. After electroweak symmetry breaking the triplet scalar gets an induced vacuum expectation value, which gives Majorana masses not only to the light neutrinos but also to the DM. Because of the Majorana mass of DM, the Z mediated elastic scattering with nucleon is forbidden. However, the Higgs boson mediated direct detection cross section of the DM gives an excellent opportunity to probe it at Xenon1T. The DM cannot be detected at the collider. However, the charged partner of the DM (often next-to-lightest stable particle) can give large displaced vertex signature at the Large Hadron Collider.
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.
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.
NASA Astrophysics Data System (ADS)
Babu, K. S.; Khan, S.
2015-10-01
We present a minimal renormalizable nonsupersymmetric S O (10 ) grand unified model with a symmetry breaking sector consisting of Higgs fields in the 5 4H+12 6H+1 0H representations. This model admits a single intermediate scale associated with Pati-Salam symmetry along with a discrete parity. Spontaneous symmetry breaking, the unification of gauge couplings, and proton lifetime estimates are studied in detail in this framework. Including threshold corrections self-consistently obtained from a full analysis of the Higgs potential, we show that the model is compatible with the current experimental bound on proton lifetime. The model generally predicts an upper bound of few times 1035 yr for proton lifetime, which is not too far from the present Super-Kamiokande limit of τp≳1.29 ×1034 yr . With the help of a Pecci-Quinn symmetry and the resulting axion, the model provides a suitable dark matter candidate while also solving the strong C P problem. The intermediate scale, MI≈(1013- 1014) GeV which is also the B -L scale, is of the right order for the right-handed neutrino mass which enables a successful description of light neutrino masses and oscillations. The Yukawa sector of the model consists of only two matrices in family space and leads to a predictive scenario for quark and lepton masses and mixings. The branching ratios for proton decay are calculable with the leading modes being p →e+π0 and p →ν ¯π+. Even though the model predicts no new physics within the reach of the LHC, the next-generation proton decay detectors and axion search experiments have the capability to reach a verdict on this minimal scenario.
A new class of Fermionic Projectors: Møller operators and mass oscillation properties
NASA Astrophysics Data System (ADS)
Drago, Nicoló; Murro, Simone
2017-09-01
Recently, a new functional analytic construction of quasi-free states for a self-dual CAR algebra has been presented in Finster and Reintjes (Adv Theor Math Phys 20:1007, 2016). This method relies on the so-called strong mass oscillation property. We provide an example where this requirement is not satisfied, due to the nonvanishing trace of the solutions of the Dirac equation on the horizon of Rindler space, and we propose a modification of the construction in order to weaken this condition. Finally, a connection between the two approaches is built.
Lattice realization of the generalized chiral symmetry in two dimensions
NASA Astrophysics Data System (ADS)
Kawarabayashi, Tohru; Aoki, Hideo; Hatsugai, Yasuhiro
2016-12-01
While it has been pointed out that the chiral symmetry, which is important for the Dirac fermions in graphene, can be generalized to tilted Dirac fermions as in organic metals, such a generalized symmetry was so far defined only for a continuous low-energy Hamiltonian. Here we show that the generalized chiral symmetry can be rigorously defined for lattice fermions as well. A key concept is a continuous "algebraic deformation" of Hamiltonians, which generates lattice models with the generalized chiral symmetry from those with the conventional chiral symmetry. This enables us to explicitly express zero modes of the deformed Hamiltonian in terms of that of the original Hamiltonian. Another virtue is that the deformation can be extended to nonuniform systems, such as fermion-vortex systems and disordered systems. Application to fermion vortices in a deformed system shows how the zero modes for the conventional Dirac fermions with vortices can be extended to the tilted case.
On the decoupling of mirror fermions
NASA Astrophysics Data System (ADS)
Chen, Chen; Giedt, Joel; Poppitz, Erich
2013-04-01
An approach to the formulation of chiral gauge theories on the lattice is to start with a vector-like theory, but decouple one chirality (the "mirror" fermions) using strong Yukawa interactions with a chirally coupled "Higgs" field. While this is an attractive idea, its viability needs to be tested with nonperturbative studies. The model that we study here, the so-called "3-4-5" model, is anomaly free and the presence of massless states in the mirror sector is not required by anomaly matching arguments, in contrast to the "1-0" model that was studied previously. We have computed the polarization tensor in this theory and find a directional discontinuity that appears to be nonzero in the limit of an infinite lattice, which is equivalent to the continuum limit at fixed physical volume. We show that a similar behavior occurs for the free massless Ginsparg-Wilson fermion, where the polarization tensor is known to have a directional discontinuity in the continuum limit. We thus find support for the conclusion that in the continuum limit of the 3-4-5 model, there are massless charged modes in the mirror sector so that it does not decouple from the light sector. The value of the discontinuity we obtain allows for two interpretations: either a chiral gauge theory does not emerge and mirror-sector fermions in a chiral anomaly free representation remain massless, or a massless vectorlike mirror fermion appears. We end by discussing some questions for future study.
NASA Astrophysics Data System (ADS)
Boucaud, Ph.; Leroy, J.-P.; Le Yaouanc, A.; Micheli, J.; Pène, O.; Rodríguez–Quintero, J.
2010-05-01
We study the quark mass function on hypercubic lattices in a large range of physical volumes and cutoffs. To avoid the very large Wilson term artefact, we exploit the relation between the quark mass function and the pseudoscalar vertex in the continuum. We extrapolate to the chiral limit. In function of the physical volume, we observe a striking discontinuity in the properties of chiral extrapolation around a physical volume Lc≃6GeV-1=1.2fm. It is present in the quark mass function, which collapses to zero, as well as in the pion mass and the quark condensate as directly calculated from the pseudoscalar correlator. It is strongly reminiscent of the phenomenon of chiral symmetry restoration observed by Neuberger and Narayanan at NC=∞ around the same physical length. In the case of spontaneous symmetry breaking, we confirm that the operator product expansion of the quark mass function, involving the quark condensate, is not operative at the available momenta, even taking into account the unusually large high order corrections to the Wilson coefficient calculated by Chetyrkin and Maier; the gap remains large, around a factor 2, even at the largest momenta available to us (p≃6GeV).
Composite Chiral Bands in the A{approx}105 Mass Region
Timar, J.; Sohler, D.; Molnar, J.; Algora, A.; Dombradi, Zs.; Krasznahorkay, A.; Zolnai, L.; Vaman, C.; Starosta, K.; Joshi, P.; Wadsworth, R.; Jenkins, D.G.; Raddon, P.M.; Simons, A.J.; Wilkinson, A.R.; Dimitrov, V.I.; Fossan, D.B.; Koike, T.; Bednarczyk, P.; Curien, D.
2005-11-21
Composite chiral bands, corresponding to the {pi}g9/2v(h11/2)2 quasiparticle configuration, have been observed in 103Rh and 105Rh. The behaviour of these bands is compared with that of the chiral bands with a {pi}g9/2vh11/2 quasiparticle configuration observed in the odd-odd 102Rh and 104Rh nuclei. This comparison shows in a model independent way that the energy separation pattern of the chiral partner bands depends strongly on the properties of the triaxial core whilst the dependence on the valence quasiparticle coupling and on the Fermi level is weaker.
Strong coupling QED with two fermionic flavors
Wang, K.C.
1990-11-01
We report the recent results of our simulation of strong coupling QED, with non-compact action, on lattices 10{sup 4} and 16{sup 4}. Since we are dealing with two staggered fermionic flavors, we use hybrid algorithm to do the simulation. In addition to the measurement of the chiral order parameter {l angle}{bar {psi}}{psi}{r angle}, we also measure magnetic monopole susceptibility, {chi}, throughout the region of chiral transition. 6 refs., 6 figs.
Coulomb's law corrections and fermion field localization in a tachyonic de Sitter thick braneworld
NASA Astrophysics Data System (ADS)
Cartas-Fuentevilla, Roberto; Escalante, Alberto; Germán, Gabriel; Herrera-Aguilar, Alfredo; Rigel Mora-Luna, Refugio
2016-05-01
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 aims we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ̅ 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 experimentally observed or
Coulomb’s law corrections and fermion field localization in a tachyonic de Sitter thick braneworld
Cartas-Fuentevilla, Roberto; Escalante, Alberto; Germán, Gabriel; Herrera-Aguilar, Alfredo; Mora-Luna, Refugio Rigel
2016-05-11
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 aims 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 experimentally
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,
NASA Astrophysics Data System (ADS)
Anisovich, A. V.; Burkert, V.; Hartmann, J.; Klempt, E.; Nikonov, V. A.; Pasyuk, E.; Sarantsev, A. V.; Strauch, S.; Thoma, U.
2017-03-01
We report a partial-wave analysis of new data on the double-polarization variable E for the reactions γp →π+ n and γp →π0 p 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 JP = 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 JP = 7 /2+. It has been suggested that chiral symmetry might be restored in the high-mass region of hadron excitations, and that these two resonances should be degenerate in mass. Our findings are in conflict with this prediction.
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→π0p 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 JP=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 JP=7/2+. It has been suggested that chiral symmetry might be restored in the high-mass region of hadron excitations, and that these two resonances should be degenerate inmore » mass. Lastly, our findings are in conflict with this prediction.« less
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.
Spontaneous breaking of chiral symmetry for confining potentials
NASA Astrophysics Data System (ADS)
Le Yaouanc, A.; Oliver, L.; Pène, O.; Raynal, J.-C.
1984-03-01
Using the Bogoliubov-Valatin variational method, we show that the chiral-invariant vacuum is unstable for a color, fourth-component vector powerlike potential rα(0<α<3) independently of the strength of the coupling constant. The fermion self-energy is negative and dominates over the positive potential energy, destabilizing the vacuum by ψ¯ψ pair condensation. This self-energy is finite but infrared singular, reflecting the behavior of the potential at large distances. We give an analytical proof of the fact that the energy of the unbroken vacuum is not minimum. The proof extends to logarithmic potentials as α-->0, but breaks down for α>=3 (number of spatial dimensions) due to severe infrared singularities. If the confining potential possesses a spin-spin piece, there are critical values of its strength, depending on the power α, beyond which the stability of the chiral-invariant vacuum is restored. In the case of the harmonic oscillator α=2, the gap equation reduces to a non-linear second-order differential equation. We find (besides the usual chiral degeneracy) an infinite number of solutions breaking chiral symmetry, higher in energy as the number of their nodes increases. We compute the expectation value of ψ¯ψ and the mass gap for the new vacuum, the lowest solution in energy. The infrared singularity of the massless fermion self-energy is removed for the stable broken solution.
Fermions and gravitational gyrotropy
NASA Astrophysics Data System (ADS)
Helfer, Adam D.
2016-12-01
In conventional general relativity without torsion, high-frequency gravitational waves couple to the chiral number density of spin one-half quanta: the polarization of the waves is rotated by 2 π N5ℓPl2, where N5 is the chiral column density and ℓPl is the Planck length. This means that if a primordial distribution of gravitational waves with E-E or B-B correlations passed through a chiral density of fermions in the very early Universe, an E-B correlation will be generated. This in turn will give rise to E-B and T-B correlations in the cosmic microwave background (CMB). Less obviously but more primitively, the condition Albrecht called "cosmic coherence" would be violated, changing the restrictions on the class of admissible cosmological gravitational waves. This altered class of waves would, generally speaking, probe earlier physics than do the conventional waves; their effects on the CMB would be most pronounced for low (≲100 ) multipoles. Rough estimates indicate that if the tensor-to-scalar ratio is less than about 10-2, it will be hard to constrain a spatially homogeneous primordial N5 by present data.
Nonperturbative Regulator for Chiral Gauge Theories?
NASA Astrophysics Data System (ADS)
Grabowska, Dorota M.; Kaplan, David B.
2016-05-01
We propose a nonperturbative gauge-invariant regulator for d -dimensional chiral gauge theories on the lattice. The method involves simulating domain wall fermions in d +1 dimensions with quantum gauge fields that reside on one d -dimensional surface and are extended into the bulk via gradient flow. The result is a theory of gauged fermions plus mirror fermions, where the mirror fermions couple to the gauge fields via a form factor that becomes exponentially soft with the separation between domain walls. The resultant theory has a local d -dimensional interpretation only if the chiral fermion representation is anomaly free. A physical realization of this construction would imply the existence of mirror fermions in the standard model that are invisible except for interactions induced by vacuum topology, and which could gravitate differently than conventional matter.
Fermion production during and after axion inflation
Adshead, Peter; Sfakianakis, Evangelos I.
2015-11-11
We study derivatively coupled fermions in axion-driven inflation, specifically m{sub ϕ}{sup 2}ϕ{sup 2} and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions.
Fermion production during and after axion inflation
Adshead, Peter; Sfakianakis, Evangelos I. E-mail: esfaki@illinois.edu
2015-11-01
We study derivatively coupled fermions in axion-driven inflation, specifically m{sub φ}{sup 2φ2} and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions.
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.
Two-Flavor Lattice-QCD Simulation in the γ Regime with Exact Chiral Symmetry
NASA Astrophysics Data System (ADS)
Fukaya, H.; Aoki, S.; Chiu, T. W.; Hashimoto, S.; Kaneko, T.; Matsufuru, H.; Noaki, J.; Ogawa, K.; Okamoto, M.; Onogi, T.; Yamada, N.
2007-04-01
We perform lattice simulations of two-flavor QCD using Neuberger’s overlap fermion, with which the exact chiral symmetry is realized at finite lattice spacings. The γ regime is reached by decreasing the light quark mass down to 3 MeV on a 163×32 lattice with a lattice spacing ˜0.11fm. We find a good agreement of the low-lying Dirac eigenvalue spectrum with the analytical predictions of the chiral random matrix theory, which reduces to the chiral perturbation theory in the γ regime. The chiral condensate is extracted as ΣMS¯(2GeV)=(251±7±11MeV)3, where the errors are statistical and an estimate of the higher order effects in the γ expansion.
Kharzeev, Dmitri E.; Yee, Ho-Ung
2011-04-15
We consider a relativistic plasma containing charged chiral fermions in an external magnetic field, e.g. a chirally symmetric quark-gluon plasma created in relativistic heavy ion collisions. We show that triangle anomalies imply the existence of a new type of collective gapless excitation in this system that stems from the coupling between the density waves of the electric and chiral charges; we call it ''the chiral magnetic wave'' (CMW). The CMW exists even in a neutral plasma, i.e. in the absence of the axial and vector chemical potentials. We demonstrate the existence of CMW and study its properties using three different approaches: i) relativistic magnetohydrodynamics; ii) dimensional reduction to (1+1) Sine-Gordon model, appropriate in a strong magnetic field; and iii) holographic QCD (Sakai-Sugimoto model), appropriate at strong coupling. We also briefly discuss the phenomenological implications of the CMW for heavy ion collisions.
Nemati, Reza; Dietz, Christopher; Anstadt, Emily; Clark, Robert; Smith, Michael; Nichols, Frank; Yao, Xudong
2017-02-28
Lipopeptides promote innate immune response and are related to disease pathology. To investigate the newly emerging roles of lipopeptides, accurate measurements of stereoisomers with multiple chiral centers are essential yet challenging. This work uses (3R)- and (3S)-(15-methyl-3-((13-methyltetradecanoyl)oxy)hexadecanoyl)glycyl-l-serine, abbreviated as l-serine-(R+S)-Lipid 654, to develop a method that combines chiral liquid chromatography, a diastereomeric mixture of isotopically labeled internal standards, and multiple reaction monitoring mass spectrometry. The new method allows for simultaneously determining the absolute configuration and quantity of stereoisomers of bacteria-derived lipopeptides. Total lipid extracts of nine evaluated bacteria strains had different amounts, but only the (R)-isoform of l-serine-Lipid 654. The developed method also allowed for the first quantitative analysis of hydrolysis of a nonphospholipid as a novel substrate of honey bee venom phospholipase A2.
Hsieh, Yunsheng; Favreau, Leonard; Cheng, K-C; Chen, Jiwen
2005-01-01
A chiral packed-column supercritical fluid chromatographic (pSFC) system coupled to tandem mass spectrometer (MS/MS) for the rapid measurements of (R,S)-propranolol and (+/-)-pindolol in metabolic stability samples was developed. The effects of the eluent flow rates and compositions, as well as of the nebulizer temperature, on the chromatographic performance and the ionization efficiency of the analytes in positive ion mode under pSFC conditions were studied. The ionization mechanism of the analytes in the CO2/methanol atmospheric pressure chemical ionization (APCI) environments with or without the use of an additive was studied. The chiral pSFC-APCI-MS/MS approach requiring approximately 2 min per sample was applied for the simultaneous determination of two pairs of racemic drugs in in vitro samples at low nanogram per milliliter concentrations. (c) 2005 John Wiley & Sons, Ltd.
Full simulation of chiral random matrix theory at nonzero chemical potential by complex Langevin
NASA Astrophysics Data System (ADS)
Mollgaard, A.; Splittorff, K.
2015-02-01
It is demonstrated that the complex Langevin method can simulate chiral random matrix theory at nonzero chemical potential. The successful match with the analytic prediction for the chiral condensate is established through a shift of matrix integration variables and choosing a polar representation for the new matrix elements before complexification. Furthermore, we test the proposal to work with a Langevin-time-dependent quark mass and find that it allows us to control the fluctuations of the phase of the fermion determinant throughout the Langevin trajectory.
Aryaeinejad, R.; Chou, W.; McHarris, W.C. )
1989-09-01
The interacting-boson-fermion-approximation and triaxial models were used to calculate excitation energies and mixing ratios for the {ital N}=80 nuclei, {sup 139}Pr, {sup 141}Pm, and {sup 143}Eu. For low-lying negative- and positive-parity states both models yield roughly the same numbers, in good agreement with experimental results. For high-lying states we find that the interacting-boson-fermion-approximation model describes the level structure considerably better than the triaxial model. On the other hand, the triaxial model gives more satisfactory results in predicting the mixing ratios.
Newmeyer, Matthew N.; Concheiro, Marta; Huestis, Marilyn A.
2014-01-01
Methamphetamine is a widely abused psychostimulant containing a chiral center. Consumption of over-the-counter and prescription medications may yield positive amphetamines results, but chiral separation of l- and d- methamphetamine and its metabolite amphetamine can help determine whether the source was licit or illicit. We present the first LC-MS/MS method with precolumn derivatization for methamphetamine and amphetamine chiral resolution in plasma and oral fluid collected with the Oral-Eze® and Quantisal™ devices. To 0.5 mL plasma, 0.75 mL Oral-Eze, or 1 mL Quantisal specimen racemic d11-methamphetamine and amphetamine internal standards were added, followed by protein precipitation. Samples were centrifuged and supernatants loaded onto pre-conditioned Phenomenex® Strata™-XC Polymeric Strong Cation solid phase extraction columns. After washing, analytes were eluted with 5% ammonium hydroxide in methanol. The eluate was evaporated to dryness and reconstituted in water. Derivatization was performed with 1-fluoro-2,4-dinitrophenyl-5-l-alanineamide (Marfey's reagent) and heating at 45°C for 1 h. Derivatized enantiomer separations were performed under isocratic conditions (methanol:water, 60:40) with a Phenomenex® Kinetex® 2.6 μm C18 column. Analytes were identified and quantified by two MRM transitions and their ratio on a 3200 QTrap (AB Sciex) mass spectrometer in ESI negative mode. In all three matrices, the method was linear for all enantiomers from 1-500 μg/L, with imprecision and accuracy of ≤11.3% and 85.3-108%, respectively. Extraction efficiencies ranged from 67.4-117% and matrix effects from -17.0-468%, with variation always ≤19.1%. Authentic plasma and OF specimens were collected from an IRB-approved study that included controlled Vicks® VapoInhaler™ administration. The present method is sensitive, selective, economic and rapid (separations accomplished in <10 min), and improves methamphetamine result interpretation. PMID:25065924
Newmeyer, Matthew N; Concheiro, Marta; Huestis, Marilyn A
2014-09-05
Methamphetamine is a widely abused psychostimulant containing a chiral center. Consumption of over-the-counter and prescription medications may yield positive amphetamines results, but chiral separation of l- and d-methamphetamine and its metabolite amphetamine can help determine whether the source was licit or illicit. We present the first LC-MS/MS method with precolumn derivatization for methamphetamine and amphetamine chiral resolution in plasma and oral fluid collected with the Oral-Eze(®) and Quantisal™ devices. To 0.5mL plasma, 0.75mL Oral-Eze, or 1mL Quantisal specimen racemic d11-methamphetamine and amphetamine internal standards were added, followed by protein precipitation. Samples were centrifuged and supernatants loaded onto pre-conditioned Phenomenex(®) Strata™-XC Polymeric Strong Cation solid phase extraction columns. After washing, analytes were eluted with 5% ammonium hydroxide in methanol. The eluate was evaporated to dryness and reconstituted in water. Derivatization was performed with 1-fluoro-2,4-dinitrophenyl-5-l-alanineamide (Marfey's reagent) and heating at 45°C for 1h. Derivatized enantiomer separations were performed under isocratic conditions (methanol:water, 60:40) with a Phenomenex(®) Kinetex(®) 2.6μm C18 column. Analytes were identified and quantified by two MRM transitions and their ratio on a 3200 QTrap (AB Sciex) mass spectrometer in ESI negative mode. In all three matrices, the method was linear for all enantiomers from 1 to 500μg/L, with imprecision and accuracy of ≤11.3% and 85.3-108%, respectively. Extraction efficiencies ranged from 67.4 to 117% and matrix effects from -17.0 to 468%, with variation always ≤19.1%. Authentic plasma and OF specimens were collected from an IRB-approved study that included controlled Vicks(®) VapoInhaler™ administration. The present method is sensitive, selective, economic and rapid (separations accomplished in <10min), and improves methamphetamine result interpretation. Published
Chiral symmetry on the lattice
Creutz, M.
1994-11-01
The author reviews some of the difficulties associated with chiral symmetry in the context of a lattice regulator. The author discusses the structure of Wilson Fermions when the hopping parameter is in the vicinity of its critical value. Here one flavor contrasts sharply with the case of more, where a residual chiral symmetry survives anomalies. The author briefly discusses the surface mode approach, the use of mirror Fermions to cancel anomalies, and finally speculates on the problems with lattice versions of the standard model.
U(1) chiral symmetry in a one-dimensional interacting electron system with spin
NASA Astrophysics Data System (ADS)
Lee, Taejin
2016-11-01
We study a spin-dependent Tomonaga-Luttinger model in one dimension, which describes electron transport through a single barrier. Using the Fermi-Bose equivalence in one dimension, we map the model onto a massless Thirring model with a boundary interaction. A field theoretical perturbation theory for the model has been developed, and the chiral symmetry is found to play an important role. The classical bulk action possesses a global U A (1)4 chiral symmetry because the fermion fields are massless. This global chiral symmetry is broken by the boundary interaction, and the bosonic degrees of freedom, corresponding to a chiral phase transformation, become dynamical. They acquire an additional kinetic action from the fermion path-integral measure and govern the critical behaviors of the physical operators. On the critical line where the boundary interaction becomes marginal, they decouple from the fermi fields. Consequently, the action reduces to the free-field action, which contains only a fermion bilinear boundary mass term as an interaction term. By using a renormalization group analysis, we obtain a new critical line, which differs from the previously known critical lines in the literature. The result of this work implies that the phase diagram of the one-dimensional electron system may have a richer structure than previously thought.
Majorana Fermions in Vortex Lattices
NASA Astrophysics Data System (ADS)
Biswas, Rudro R.
2013-09-01
We consider Majorana fermions tunneling among an array of vortices in a 2D chiral p-wave superconductor or equivalent material. The amplitude for Majorana fermions to tunnel between a pair of vortices is found to necessarily depend on the background superconducting phase profile; it is found to be proportional to the sine of half the difference between the phases at the two vortices. Using this result we study tight-binding models of Majorana fermions in vortices arranged in triangular or square lattices. In both cases we find that the aforementioned phase-tunneling relationship leads to the creation of superlattices where the Majorana fermions form macroscopically degenerate localizable flat bands at zero energy, in addition to other dispersive bands. This finding suggests that tunneling processes in these vortex arrays do not change the energies of a finite fraction of Majorana fermions, contrary to previous expectation. The presence of flat Majorana bands, and hence less-than-expected decoherence in these vortex arrays, bodes well for the prospects of topological quantum computation with large numbers of Majorana states.
Majorana fermions in vortex lattices.
Biswas, Rudro R
2013-09-27
We consider Majorana fermions tunneling among an array of vortices in a 2D chiral p-wave superconductor or equivalent material. The amplitude for Majorana fermions to tunnel between a pair of vortices is found to necessarily depend on the background superconducting phase profile; it is found to be proportional to the sine of half the difference between the phases at the two vortices. Using this result we study tight-binding models of Majorana fermions in vortices arranged in triangular or square lattices. In both cases we find that the aforementioned phase-tunneling relationship leads to the creation of superlattices where the Majorana fermions form macroscopically degenerate localizable flat bands at zero energy, in addition to other dispersive bands. This finding suggests that tunneling processes in these vortex arrays do not change the energies of a finite fraction of Majorana fermions, contrary to previous expectation. The presence of flat Majorana bands, and hence less-than-expected decoherence in these vortex arrays, bodes well for the prospects of topological quantum computation with large numbers of Majorana states.
Chiral phase transition in QED3 at finite temperature
NASA Astrophysics Data System (ADS)
Yin, Pei-Lin; Xiao, Hai-Xiao; Wei, Wei; Feng, Hong-Tao; Zong, Hong-Shi
2016-12-01
In the framework of Dyson-Schwinger equations, we employ two kinds of criteria (one kind is the chiral condensate, the other kind is thermodynamic quantities, such as the pressure, the entropy, and the specific heat) to investigate the nature of chiral phase transitions in QED3 for different fermion flavors. It is found that the chiral phase transitions in QED3 for different fermion flavors are all typical second-order phase transitions; the critical temperature and order of the chiral phase transition obtained from the chiral condensate and susceptibility are the same with that obtained by the thermodynamic quantities, which means that they are equivalent in describing the chiral phase transition; the critical temperature decreases as the number of fermion flavors increases and there is a boundary that separates the Tc-Nf plane into chiral symmetry breaking and restoration regions.
Fermions Living in a Flat World
Jesus Anguiano-Galicia, Ma. de; Bashir, A.
2006-09-25
In a plane, parity transformation, which changes the sign of only one spatial coordinate, swaps the fermion fields living in two inequivalent representations. A parity invariant Lagrangian thus contains fields corresponding to both the representations. For such a Lagrangian, we show that we can also define a chiral symmetry.
Chiral magnetic effect in condensed matter systems
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 3D Dirac/Weyl semimetals.
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.
On the Locality and Scaling of Overlap Fermions at Coarse Lattice Spacings
Terrence Draper; Nilmani Mathur; Jianbo Zhang; Andrei Alexandru; Ying Chen; Shao-Jing Dong; Ivan Horvath; Frank X. Lee; Keh-Fei Liu; Sonali Tamhankar
2006-11-07
The overlap fermion offers the considerable advantage of exact chiral symmetry on the lattice, but is numerically intensive. This can be made affordable while still providing large lattice volumes, by using coarse lattice spacing, given that good scaling and localization properties are established. Here, using overlap fermions on quenched Iwasaki gauge configurations, we demonstrate directly that, with appropriate choice of negative Wilson's mass, the overlap Dirac operator's range is comfortably small in lattice units for each of the lattice spacings 0.20 fm, 0.17 fm, and 0.13 fm (and scales to zero in physical units in the continuum limit). In particular, our direct results contradict recent speculation that an inverse lattice spacing of 1 GeV is too low to have satisfactory localization. Furthermore, hadronic masses (available on the two coarser lattices) scale very well.
Two-flavor QCD simulation with exact chiral symmetry
Aoki, S.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Ishikawa, K-I.; Okawa, M.; Kanaya, K.; Matsufuru, H.; Okamoto, M.; Onogi, T.; Ukawa, A; Yoshie, T.
2008-07-01
We perform numerical simulations of lattice QCD with two flavors of dynamical overlap quarks, which have exact chiral symmetry on the lattice. While this fermion discretization is computationally demanding, we demonstrate the feasibility to simulate reasonably large and fine lattices by a careful choice of the lattice action and algorithmic improvements. Our production runs are carried out on a 16{sup 3}x32 lattice at a single lattice spacing around 0.12 fm. We explore the sea quark mass region down to m{sub s}/6, where m{sub s} is the physical strange quark mass, for a good control of the chiral extrapolation in future calculations of physical observables. We describe in detail our setup and algorithmic properties of the production simulations and present results for the static quark potential to fix the lattice scale and the locality of the overlap operator.
NASA Astrophysics Data System (ADS)
Barik, N.; Mishra, R. N.; Mohanty, D. K.; Panda, P. K.; Frederico, T.
2013-07-01
We have calculated the properties of nuclear matter in a self-consistent manner with a quark-meson coupling mechanism incorporating the structure of nucleons in vacuum through a relativistic potential model; where the dominant confining interaction for the free independent quarks inside a nucleon is represented by a phenomenologically average potential in equally mixed scalar-vector harmonic form. Corrections due to spurious center of mass motion as well as those due to other residual interactions, such as the one gluon exchange at short distances and quark-pion coupling arising out of chiral symmetry restoration, have been considered in a perturbative manner to obtain the nucleon mass in vacuum. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to σ and ω mesons through mean field approximations. The relevant parameters of the interaction are obtained self-consistently while realizing the saturation properties such as the binding energy, pressure, and compressibility of the nuclear matter. We also discuss some implications of chiral symmetry in nuclear matter along with the nucleon and nuclear σ term and the sensitivity of nuclear matter binding energy with variations in the light quark mass.
Large-Nc gauge theory and chiral random matrix theory
NASA Astrophysics Data System (ADS)
Hanada, Masanori; Lee, Jong-Wan; Yamada, Norikazu
2013-07-01
We discuss how the 1/Nc expansion and the chiral random matrix theory (χRMT) can be used in the study of large-Nc gauge theories. We first clarify the parameter region in which each of these two approaches is valid. While the fermion mass m is fixed in the standard large-Nc arguments (’t Hooft large-Nc limit), m must be scaled appropriately with a certain negative power of Nc in order for the gauge theories to be described by the χRMT. Then, although these two limits are not compatible in general, we show that the breakdown of chiral symmetry can be detected by combining the large-Nc argument and the χRMT with some care. As a concrete example, we numerically study the four-dimensional SU(Nc) gauge theory with Nf=2 heavy adjoint fermions, introduced as the center symmetry preserver keeping the infrared physics intact, on a 24 lattice. By looking at the low-lying eigenvalues of the overlap-Dirac operator for a massless probe fermion in the adjoint representation, we find that the chiral symmetry is indeed broken with the expected breaking pattern. This result reproduces a well-known fact that the chiral symmetry is spontaneously broken in the pure SU(Nc) gauge theory in the large-Nc and the large-volume limit and therefore supports the validity of the combined approach. We also provide an interpretation of the gap and unexpected Nc scaling, both of which are observed in the Dirac spectrum.
Lattice QCD with the overlap fermions at strong gauge coupling
NASA Astrophysics Data System (ADS)
Ichinose, Ikuo; Nagao, Keiichi
2000-06-01
We generalize overlap fermion by Narayanan and Neuberger by introducing a hopping parameter t . This lattice fermion has desirable properties as the original overlap fermion. We expand "Dirac" operator of this fermion in powers of t . Higher-order terms of t are long-distance terms and this t -expansion is a kind of the hopping expansion. It is shown that the Ginsparg-Wilson relation is satisfied at each order of t . We show that this t -expansion is useful for study of the strong-coupling gauge theory. We apply this formalism to the lattice QCD and study its chiral phase structure at strong coupling. We find that there are (at least) two phases one of which has desired chiral properties of QCD. Possible phase structure of the lattice QCD with the overlap fermions is proposed.
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 pseudoscalar 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.
Gauge invariant smearing and the extraction of excited state masses using Wilson fermions at β = 6.2
NASA Astrophysics Data System (ADS)
Ukqcd Collaboration
1993-03-01
We present an investigation of gauge invariant smearing for Wilson fermions on a 24 3 × 48 lattice at β = 6.2. We demonstrate a smearing algorithm that allows a substantial improvement in the determination of the baryon spectrum obtained using propagators smeared at both source and sink, at only a small computational cost. We investigate the matrix of correlators constructed from local and smeared operators, and are able to expose excited states of both the mesons and baryons.
Observing remnants by fermions' tunneling
Chen, D.Y.; Wu, H.W.; Yang, H. E-mail: iverwu@uestc.edu.cn
2014-03-01
The standard Hawking formula predicts the complete evaporation of black holes. In this paper, we introduce effects of quantum gravity into fermions' tunneling from Reissner-Nordstrom and Kerr black holes. The quantum gravity effects slow down the increase of Hawking temperatures. This property naturally leads to a residue mass in black hole evaporation. The corrected temperatures are affected by the quantum numbers of emitted fermions. Meanwhile, the temperature of the Kerr black hole is a function of θ due to the rotation.
Phase diagram of chirally imbalanced QCD matter
Chernodub, M. N.; Nedelin, A. S.
2011-05-15
We compute the QCD phase diagram in the plane of the chiral chemical potential and temperature using the linear sigma model coupled to quarks and to the Polyakov loop. The chiral chemical potential accounts for effects of imbalanced chirality due to QCD sphaleron transitions which may emerge in heavy-ion collisions. We found three effects caused by the chiral chemical potential: the imbalanced chirality (i) tightens the link between deconfinement and chiral phase transitions; (ii) lowers the common critical temperature; (iii) strengthens the order of the phase transition by converting the crossover into the strong first order phase transition passing via the second order end point. Since the fermionic determinant with the chiral chemical potential has no sign problem, the chirally imbalanced QCD matter can be studied in numerical lattice simulations.
Dynamical chiral symmetry breaking in the NJL model with a constant external magnetic field
NASA Astrophysics Data System (ADS)
Shi, Song; Yang, You-Chang; Xia, Yong-Hui; Cui, Zhu-Fang; Liu, Xiao-Jun; Zong, Hong-Shi
2015-02-01
In this paper, we develop a new method that is different from the Schwinger proper time method to deduce the fermion propagator with a constant external magnetic field. In the NJL model, we use this method to find the gap equation at zero and nonzero temperature and give the numerical results and phase diagram between the magnetic field and temperature. Additionally, we introduce the current mass to study the susceptibilities because there is a new parameter (the strength of the external magnetic field) in this problem. Corresponding to this new parameter, we define a new susceptibility χB to compare with the other two susceptibilities χc (chiral susceptibility) and χT (thermal susceptibility). All three susceptibilities show that when the current mass is not zero, the phase transition is a crossover, while for comparison, in the chiral limit, the susceptibilities show a second order phase transition. Last, we give the critical coefficients of different susceptibilities in the chiral limit.
On the trace anomaly of a Weyl fermion
NASA Astrophysics Data System (ADS)
Bastianelli, Fiorenzo; Martelli, Riccardo
2016-11-01
We calculate the trace anomaly of a Weyl fermion coupled to gravity by using Fujikawa's method supplemented by a consistent regulator. The latter is constructed out of Pauli-Villars regulating fields. The motivation for presenting such a calculation stems from recent studies that suggest that the trace anomaly of chiral fermions in four dimensions might contain an imaginary part proportional to the Pontryagin density. We find that the trace anomaly of a Weyl fermion is given by half the trace anomaly of a Dirac fermion, so that no imaginary part proportional to the Pontryagin density is seen to arise.
Fried, Karen M; Young, Andrea E; Usdin Yasuda, Sally; Wainer, Irving W
2002-01-15
A sensitive enantioselective high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of plasma concentrations of (-)(R)- and (+)(S)-chlorpheniramine (CP) and their metabolites, desmethyl-chlorpheniramine (DCP), didesmethyl-chorpheniramine (DDCP) and chlorpheniramine N-oxide (CPNO). Enantioselective separations were achieved on a beta-cyclodextrin chiral stationary phase (CYCLOBOND I 2000) with a mobile phase consisting of diethylamine acetate (0.25%, pH 4.4):methanol:acetonitrile [85:7.5:7.5, (v/v/v)]and a flow-rate of 0.5 ml/min. For CP, the enantioselectivity (alpha) of the separation was 1.12 with a resolution factor (R(s)) of 1.17. The method was validated for CP by using mass spectroscopy detection (MSD). Concentrations of each enantiomer could be measured down to 125 pg/ml from a 1-ml plasma sample. Extracted calibration curves were linear from 0.13 to 50.00 ng/ml for each enantiomer. The method was applied to samples from two clinical studies.
Zhang, Zhaoxian; Zhang, Qing; Gao, Beibei; Gou, Gaozhang; Li, Lianshan; Shi, Haiyan; Wang, Minghua
2017-09-20
An efficient and sensitive chiral analytical method was established for the determination of the chiral fungicide prothioconazole and its major chiral metabolite prothioconazole-desthio in agricultural and environmental samples using ultraperformance liquid chromatography-tandem mass spectrometry. The optical rotation and absolute configuration of enantiomers were identified by optical rotation detector and electronic circular dichroism spectra. The elution order of prothioconazole and its chiral metabolite enantiomers was R-(+)-prothioconazole-desthio, S-(-)-prothioconazole-desthio, R-(-)-prothioconazole, and S-(+)-prothioconazole. The mean recoveries from the samples was 71.8-102.0% with intraday relative standard deviations (RSDs) of 0.3-11.9% and interday RSDs of 0.9-10.6%. The formation of prothioconazole-desthio was studied in soil under field conditions and enantioselective degradation was observed for chiral prothioconazole. Remarkable enantioselective degradation was observed: R-prothioconazole degraded preferentially with EF values from 0.48 to 0.37. Although prothioconazole-desthio is the most remarkably bioactive metabolite, no obvious enantioselective behavior was observed in soil. These results may help to systematically evaluate prothioconazole and its metabolites in food and environmental safety.
Fermion localization in a backreacted warped spacetime
NASA Astrophysics Data System (ADS)
Paul, Tanmoy; SenGupta, Soumitra
2017-06-01
We consider a five dimensional anti-de Sitter (AdS) warped spacetime in presence of a massive scalar field in the bulk. The scalar field potential fulfills the requirement of modulus stabilization even when the effect of backreaction of the stabilizing field is taken into account. In such a scenario, we explore the role of backreaction on the localization of bulk fermions which in turn determines the effective radion-fermion coupling on the brane. Our result reveals that both the chiral modes of the zeroth Kaluza-Klein (KK) fermions get localized near TeV brane as the backreaction of the scalar field increases. We also show that the profile of massive KK fermions shifts towards the Planck brane with an increasing backreaction parameter. Some implications in the context of LHC physics are discussed.
Light quark simulations with FLIC fermions
J.M. Zanotti; D.B. Leinweber; W. Melnitchouk; A.G. Williams; J.B. Zhang
2002-06-01
Hadron masses are calculated in quenched lattice QCD in order to probe the scaling behavior of a novel fat-link clover fermion action in which only the irrelevant operators of the fermion action are constructed using APE-smeared links. Light quark masses corresponding to an m{sub pi}/m{sub p} ratio of 0.35 are considered to assess the exceptional configuration problem of clover-fermion actions. This Fat-Link Irrelevant Clover (FLIC) fermion action provides scaling which is superior to mean-field improvement and offers advantages over nonperturbative improvement, including reduced exceptional configurations.
Wang, Zhijun; Alexandradinata, A; Cava, R J; Bernevig, B Andrei
2016-04-14
Spatial symmetries in crystals may be distinguished by whether they preserve the spatial origin. Here we study spatial symmetries that translate the origin by a fraction of the lattice period, and find that these non-symmorphic symmetries protect an exotic surface fermion whose dispersion relation is shaped like an hourglass; surface bands connect one hourglass to the next in an unbreakable zigzag pattern. These 'hourglass' fermions are formed in the large-gap insulators, KHgX (X = As, Sb, Bi), which we propose as the first material class whose band topology relies on non-symmorphic symmetries. Besides the hourglass fermion, another surface of KHgX manifests a three-dimensional generalization of the quantum spin Hall effect, which has previously been observed only in two-dimensional crystals. To describe the bulk topology of non-symmorphic crystals, we propose a non-Abelian generalization of the geometric theory of polarization. Our non-trivial topology originates from an inversion of the rotational quantum numbers, which we propose as a criterion in the search for topological materials.
NASA Astrophysics Data System (ADS)
Wang, Zhijun; Alexandradinata, A.; Cava, Robert J.; Bernevig, B. Andrei
Spatial symmetries in crystals are distinguished by whether they preserve the spatial origin. We show how this basic geometric property gives rise to a new topology in band insulators. We study spatial symmetries that translate the origin by a fraction of the lattice period, and find that these nonsymmorphic symmetries protect a novel surface fermion whose dispersion is shaped like an hourglass; surface bands connect one hourglass to the next in an unbreakable zigzag pattern. These exotic fermions are materialized in the large-gap insulators: KHg X (X = As,Sb,Bi), which we propose as the first material class whose topology relies on nonsymmorphic symmetries. Beside the hourglass fermion, a different surface of KHg X manifests a 3D generalization of the quantum spin Hall effect. To describe the bulk topology of nonsymmorphic crystals, we propose a non-Abelian generalization of the geometric theory of polarization. Our nontrivial topology originates not from an inversion of the parity quantum numbers, but rather of the rotational quantum numbers, which we propose as a fruitful in the search for topological materials. Finally, KHg X uniquely exemplifies a cohomological insulator, a concept that we will introduce in a companion work.
B_K in unquenched QCD using improved staggered fermions
NASA Astrophysics Data System (ADS)
Kim, Jongjeong
2006-12-01
We present preliminary results for BK calculated using improved staggered fermions with a mixed action (HYP-smeared staggered valence quarks and AsqTad staggered sea quarks). We investigate £¡ ¢ a2¤ effect due to non- the effect of non-degenerate quarks on BK and attempt to estimate the Goldstone pions in loops. We fit the data to continuum partially quenched chiral perturbation theory. We find that the quality of fit for BK improves if we include non-degenerate quark mass combinations. We also observe, however, that the fitting curve deviates from the data points in the light quark mass region. This may indicate the need to include taste-breaking in pion loops.
Domain-Wall Induced Quark Masses in Topologically-Nontrivial Background
NASA Astrophysics Data System (ADS)
Gadiyak, Valeriya; Ji, Xiangdong; Jung, Chulwoo
2000-10-01
Chiral symmetry and its explicit and/or spontaneous breaking are important aspects of strong interaction phenomenology. Chiral dynamics dominates the low-energy hadron structure and interactions. The chiral phase transition at finite temperature has been sought after experimentally for a long time. On the theoretical frontier massless fermions defy the naive nonperturbative treatments. In the last few years, Kaplan and Shamir's domain-wall construction and Narayanan and Neuberger's overlap fermion formalism have emerged as promising approaches to simulating massless quarks. In our work, we aim to study the effectiveness of the domain-wall approach. Following previous studies, we adopt Shamir's version of the domain wall fermion formulation, in which the 5-dimensional Wilson fermion is first introduced. We have studied the induced quark mass resulted from the finite domain wall separation by diagonalizing the hermitian domain-wall Dirac operator in topologically nontrivial configurations. We find the quantum fluctuation strongly enhances the domain-wall effects. However, the effective mass does show an exponential decay as a function of Ls (length of the 5th dimension). Our result on an 8^4 lattice with b=6 is consistent with the effective fermion masses from the Gell-Mann-Oakes-Renner (GMOR) relation, although a detailed analysis shows that the two definitions of the effective mass are not the same. Finally, we comment on the size of Ls needed in a practical Monte Carlo simulation.
Chiral Lagrangian from Duality and Monopole Operators in Compactified QCD
NASA Astrophysics Data System (ADS)
Cherman, Aleksey; Schäfer, Thomas; Ünsal, Mithat
2016-08-01
We show that there exists a special compactification of QCD on R3×S1 in which the theory has a domain where continuous chiral symmetry breaking is analytically calculable. We give a microscopic derivation of the chiral Lagrangian, the chiral condensate, and the Gell-Mann-Oakes-Renner relation mπ2fπ2=-mq⟨q ¯ q ⟩ . Abelian duality, monopole operators, and flavor-twisted boundary conditions play the main roles. The flavor twisting leads to the new effect of fractional jumping of fermion zero modes among monopole instantons. Chiral symmetry breaking is induced by monopole-instanton operators, and the Nambu-Goldstone pions arise by color-flavor transmutation from gapless "dual photons." We also give a microscopic picture of the "constituent quark" masses. Our results are consistent with expectations from chiral perturbation theory at large S1, and yield strong support for adiabatic continuity between the small-S1 and large-S1 regimes. We also find concrete microscopic connections between N =1 and N =2 supersymmetric gauge theory dynamics and nonsupersymmetric QCD dynamics.
Chiral Lagrangian from Duality and Monopole Operators in Compactified QCD.
Cherman, Aleksey; Schäfer, Thomas; Ünsal, Mithat
2016-08-19
We show that there exists a special compactification of QCD on R^{3}×S^{1} in which the theory has a domain where continuous chiral symmetry breaking is analytically calculable. We give a microscopic derivation of the chiral Lagrangian, the chiral condensate, and the Gell-Mann-Oakes-Renner relation m_{π}^{2}f_{π}^{2}=-m_{q}⟨q[over ¯]q⟩. Abelian duality, monopole operators, and flavor-twisted boundary conditions play the main roles. The flavor twisting leads to the new effect of fractional jumping of fermion zero modes among monopole instantons. Chiral symmetry breaking is induced by monopole-instanton operators, and the Nambu-Goldstone pions arise by color-flavor transmutation from gapless "dual photons." We also give a microscopic picture of the "constituent quark" masses. Our results are consistent with expectations from chiral perturbation theory at large S^{1}, and yield strong support for adiabatic continuity between the small-S^{1} and large-S^{1} regimes. We also find concrete microscopic connections between N=1 and N=2 supersymmetric gauge theory dynamics and nonsupersymmetric QCD dynamics.
Aoki phases in the lattice Gross-Neveu model with flavored mass terms
Creutz, Michael; Kimura, Taro; Misumi, Tatsuhiro
2011-05-01
We investigate the parity-broken phase structure for staggered and naive fermions in the Gross-Neveu model as a toy model of QCD. We consider a generalized staggered Gross-Neveu model including two types of four-point interactions. We use generalized mass terms to split the doublers for both staggered and naive fermions. The phase boundaries derived from the gap equations show that the mass splitting of tastes results in an Aoki phase both in the staggered and naive cases. We also discuss the continuum limit of these models and explore taking the chirally symmetric limit by fine-tuning a mass parameter and two-coupling constants. This supports the idea that in lattice QCD we can derive one- or two-flavor staggered fermions by tuning the mass parameter, which are likely to be less expensive than Wilson fermions in QCD simulation.
Strong CP problem, up-quark mass, and the Randall-Sundrum microscope
Davoudiasl, Hooman; Soni, Amarjit
2007-11-01
In the Randall-Sundrum model, setting the ratio of up- and down-quark masses m{sub u}/m{sub d}<<1, relevant to the strong CP problem, does not require chiral symmetry or fine-tuning, due to exponential bulk fermion profiles. We point out that such geometric suppression of the mass of a fermion magnifies the masses of its corresponding Kaluza-Klein (KK) states. In this sense, these KK states act as 'microscopes' for probing light quark and lepton masses. In simple realizations, this hypothesis can be testable at future colliders, like the LHC, by measuring the spectrum of level-1 KK fermions. The microscope can then provide an experimental test for the vanishing of m{sub u} in the ultraviolet, independently of nonperturbative determinations, by lattice simulations or other means, at hadronic scales. We also briefly comment on application of our microscope idea to other fermions, such as the electron and neutrinos.
Awramik, M; Czakon, M; Freitas, A; Weiglein, G
2004-11-12
We present a complete calculation of the contributions to the effective leptonic weak mixing angle, sin((2)theta;(lept)(eff), generated by closed fermion loops at the two-loop level of the electroweak interactions. This quantity is the source of the most stringent bound on the mass M(H) of the standard model Higgs boson. The size of the corrections with respect to known partial results varies between -4 x 10(-5) and -8 x 10(-5) for a realistic range of M(H) from 100 to 300 GeV. This translates into a shift of the predicted (from sin((2)theta;(lept)(eff) alone) central value of M(H) by +19 GeV, to be compared with the shift induced by a recent change in the measured top quark mass which amounts to +36 GeV.
NASA Astrophysics Data System (ADS)
Aaltonen, T.; Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T.; Adelman, J.; Aguilo, E.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Álvarez González, B.; Alverson, G.; Alves, G. A.; Amerio, S.; Amidei, D.; Anastassov, A.; Ancu, L. S.; Annovi, A.; Antos, J.; Aoki, M.; Apollinari, G.; Appel, J.; Apresyan, A.; Arisawa, T.; Arnoud, Y.; Arov, M.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Askew, A.; Åsman, B.; Atramentov, O.; Attal, A.; Aurisano, A.; Avila, C.; Azfar, F.; Backusmayes, J.; Badaud, F.; Badgett, W.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barbaro-Galtieri, A.; Barberis, E.; Barfuss, A.-F.; Baringer, P.; Barnes, V. E.; Barnett, B. A.; Barreto, J.; Barria, P.; Bartlett, J. F.; Bartos, P.; Bassler, U.; Bauer, G.; Beale, S.; Bean, A.; Beauchemin, P.-H.; Bedeschi, F.; Beecher, D.; Begalli, M.; Begel, M.; Behari, S.; Belanger-Champagne, C.; Bellantoni, L.; Bellettini, G.; Bellinger, J.; Benitez, J. A.; Benjamin, D.; Beretvas, A.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Beuselinck, R.; Bezzubov, V. A.; Bhat, P. C.; Bhatnagar, V.; Bhatti, A.; Binkley, M.; Bisello, D.; Bizjak, I.; Blair, R. E.; Blazey, G.; Blessing, S.; Blocker, C.; Bloom, K.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boehnlein, A.; Boisvert, V.; Boline, D.; Bolton, T. A.; Boos, E. E.; Borissov, G.; Bortoletto, D.; Bose, T.; Boudreau, J.; Boveia, A.; Brandt, A.; Brau, B.; Bridgeman, A.; Brigliadori, L.; Brock, R.; Bromberg, C.; Brooijmans, G.; Bross, A.; Brown, D.; Brubaker, E.; Bu, X. B.; Buchholz, D.; Budagov, J.; Budd, H. S.; Budd, S.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Burkett, K.; Burnett, T. H.; Busetto, G.; Bussey, P.; Buszello, C. P.; Buzatu, A.; Byrum, K. L.; Cabrera, S.; Calancha, C.; Calfayan, P.; Calpas, B.; Calvet, S.; Camacho-Pérez, E.; Camarda, S.; Cammin, J.; Campanelli, M.; Campbell, M.; Canelli, F.; Canepa, A.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrasco-Lizarraga, M. A.; Carrera, E.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Casey, B. C. K.; Castilla-Valdez, H.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chakrabarti, S.; Chakraborty, D.; Chan, K. M.; Chandra, A.; Chang, S. H.; Chen, G.; Chen, Y. C.; Chertok, M.; Chevalier-Théry, S.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, D. K.; Cho, K.; Cho, S. W.; Choi, S.; Chokheli, D.; Chou, J. P.; Choudhary, B.; Christoudias, T.; Chung, K.; Chung, W. H.; Chung, Y. S.; Chwalek, T.; Cihangir, S.; Ciobanu, C. I.; Ciocci, M. A.; Claes, D.; Clark, A.; Clark, D.; Clutter, J.; Compostella, G.; Convery, M. E.; Conway, J.; Cooke, M.; Cooper, W. E.; Corbo, M.; Corcoran, M.; Cordelli, M.; Couderc, F.; Cousinou, M.-C.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Croc, A.; Cuenca Almenar, C.; Cuevas, J.; Culbertson, R.; Cully, J. C.; Cutts, D.; Ćwiok, M.; Dagenhart, D.; D'Ascenzo, N.; Das, A.; Datta, M.; Davies, G.; Davies, T.; de, K.; de Barbaro, P.; de Cecco, S.; Deisher, A.; de Jong, S. J.; de La Cruz-Burelo, E.; Déliot, F.; Dell'Orso, M.; de Lorenzo, G.; Deluca, C.; Demarteau, M.; Demina, R.; Demortier, L.; Deng, J.; Deninno, M.; Denisov, D.; Denisov, S. P.; D'Errico, M.; Desai, S.; Devaughan, K.; di Canto, A.; Diehl, H. T.; Diesburg, M.; di Ruzza, B.; Dittmann, J. R.; Dominguez, A.; Donati, S.; Dong, P.; D'Onofrio, M.; Dorigo, T.; Dorland, T.; Dube, S.; Dubey, A.; Dudko, L. V.; Duggan, D.; Duperrin, A.; Dutt, S.; Dyshkant, A.; Eads, M.; Ebina, K.; Edmunds, D.; Elagin, A.; Ellison, J.; Elvira, V. D.; Enari, Y.; Eno, S.; Erbacher, R.; Errede, D.; Errede, S.; Ershaidat, N.; Eusebi, R.; Evans, H.; Evdokimov, A.; Evdokimov, V. N.; Facini, G.; Fang, H. C.; Farrington, S.; Fedorko, W. T.; Feild, R. G.; Feindt, M.; Ferapontov, A. V.; Ferbel, T.; Fernandez, J. P.; Ferrazza, C.; Fiedler, F.; Field, R.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Flanagan, G.; Forrest, R.; Fortner, M.; Fox, H.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Fuess, S.; Furic, I.; Gadfort, T.; Gallinaro, M.; Galyardt, J.; Garberson, F.; Garcia, J. E.; Garcia-Bellido, A.; Garfinkel, A. F.; Garosi, P.; Gavrilov, V.; Gay, P.; Geist, W.; Geng, W.; Gerbaudo, D.; Gerber, C. E.; Gerberich, H.; Gerdes, D.; Gershtein, Y.; Gessler, A.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Gillberg, D.; Gimmell, J. L.; Ginsburg, C. M.; Ginther, G.; Giokaris, N.; Giordani, M.; Giromini, P.; Giunta, M.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldschmidt, N.; Golossanov, A.; Golovanov, G.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Goussiou, A.; Grannis, P. D.; Greder, S.; Greenlee, H.; Greenwood, Z. D.; Gregores, E. M.; Grenier, G.; Gresele, A.; Grinstein, S.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grosso-Pilcher, C.; Group, R. C.; Grundler, U.; Grünendahl, S.; Grünewald, M. W.; Guimaraes da Costa, J.; Gunay-Unalan, Z.; Guo, F.; Guo, J.; Gutierrez, G.; Gutierrez, P.; Haas, A.; Haber, C.; Haefner, P.; Hagopian, S.; Hahn, S. R.; Haley, J.; Halkiadakis, E.; Hall, I.; Han, B.-Y.; Han, J. Y.; Han, L.; Happacher, F.; Hara, K.; Harder, K.; Hare, D.; Hare, M.; Harel, A.; Harr, R. F.; Hartz, M.; Hatakeyama, K.; Hauptman, J. M.; Hays, C.; Hays, J.; Hebbeker, T.; Heck, M.; Hedin, D.; Heinrich, J.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-de La Cruz, I.; Herndon, M.; Herner, K.; Hesketh, G.; Heuser, J.; Hewamanage, S.; Hidas, D.; Hildreth, M. D.; Hill, C. S.; Hirosky, R.; Hirschbuehl, D.; Hoang, T.; Hobbs, J. D.; Hocker, A.; Hoeneisen, B.; Hohlfeld, M.; Hossain, S.; Houben, P.; Hou, S.; Houlden, M.; Hsu, S.-C.; Hu, Y.; Hubacek, Z.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Huske, N.; Hussein, M.; Huston, J.; Hynek, V.; Iashvili, I.; Illingworth, R.; Incandela, J.; Introzzi, G.; Iori, M.; Ito, A. S.; Ivanov, A.; Jabeen, S.; Jaffré, M.; Jain, S.; James, E.; Jamin, D.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jesik, R.; Jha, M. K.; Jindariani, S.; Johns, K.; Johnson, C.; Johnson, M.; Johnson, W.; Johnston, D.; Jonckheere, A.; Jones, M.; Jonsson, P.; Joo, K. K.; Jun, S. Y.; Jung, J. E.; Junk, T. R.; Juste, A.; Kaadze, K.; Kajfasz, E.; Kamon, T.; Kar, D.; Karchin, P. E.; Karmanov, D.; Kasper, P. A.; Kato, Y.; Katsanos, I.; Kehoe, R.; Kephart, R.; Kermiche, S.; Ketchum, W.; Keung, J.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Khatidze, D.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, H. W.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kimura, N.; Kirby, M. H.; Kirsch, L.; Kirsch, M.; Klimenko, S.; Kohli, J. M.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Korytov, A.; Kotwal, A. V.; Kozelov, A. V.; Kraus, J.; Kreps, M.; Kroll, J.; Krop, D.; Krumnack, N.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kulkarni, N. P.; Kumar, A.; Kupco, A.; Kurata, M.; Kurča, T.; Kuzmin, V. A.; Kvita, J.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lammers, S.; Lancaster, M.; Lander, R. L.; Landsberg, G.; Lannon, K.; Lath, A.; Latino, G.; Lazzizzera, I.; Lebrun, P.; Lecompte, T.; Lee, E.; Lee, H. S.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Lee, W. M.; Lellouch, J.; Leone, S.; Lewis, J. D.; Li, L.; Li, Q. Z.; Lietti, S. M.; Lim, J. K.; Linacre, J.; Lincoln, D.; Lin, C.-J.; Lindgren, M.; Linnemann, J.; Lipaev, V. V.; Lipeles, E.; Lipton, R.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, T.; Liu, Y.; Liu, Z.; Lobodenko, A.; Lockyer, N. S.; Loginov, A.; Lokajicek, M.; Lovas, L.; Love, P.; Lubatti, H. J.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Luna-Garcia, R.; Lungu, G.; Lyon, A. L.; Lysak, R.; Lys, J.; Maciel, A. K. A.; Mackin, D.; MacQueen, D.; Madar, R.; Madrak, R.; Maeshima, K.; Magaña-Villalba, R.; Makhoul, K.; Maksimovic, P.; Mal, P. K.; Malde, S.; Malik, S.; Malik, S.; Malyshev, V. L.; Manca, G.; Manousakis-Katsikakis, A.; Maravin, Y.; Margaroli, F.; Marino, C.; Marino, C. P.; Martin, A.; Martin, V.; Martínez, M.; Martínez-Ballarín, R.; Martínez-Ortega, J.; Mastrandrea, P.; Mathis, M.; Mattson, M. E.; Mazzanti, P.; McCarthy, R.; McFarland, K. S.; McGivern, C. L.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Menzione, A.; Mercadante, P. G.; Merkin, M.; Mesropian, C.; Meyer, A.; Meyer, J.; Miao, T.; Mietlicki, D.; Miladinovic, N.; Miller, R.; Mills, C.; Milnik, M.; Mitra, A.; Mitselmakher, G.; Miyake, H.; Moed, S.; Moggi, N.; Mondal, N. K.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Moulik, T.; Movilla Fernandez, P.; Muanza, G. S.; Mukherjee, A.; Mulhearn, M.; Muller, Th.; Mülmenstädt, J.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nagy, E.; Naimuddin, M.; Nakamura, K.; Nakano, I.; Napier, A.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Nett, J.; Neu, C.; Neubauer, M. S.; Neubauer, S.; Neustroev, P.; Nielsen, J.; Nilsen, H.; Nodulman, L.; Norman, M.; Norniella, O.; Novaes, S. F.; Nunnemann, T.; Nurse, E.; Oakes, L.; Obrant, G.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Onoprienko, D.; Orava, R.; Orduna, J.; Osman, N.; Osta, J.; Osterberg, K.; Otero Y Garzón, G. J.; Owen, M.; Padilla, M.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Pangilinan, M.; Papadimitriou, V.; Papaikonomou, A.; Paramanov, A. A.; Parashar, N.; Parihar, V.; Park, S.-J.; Park, S. K.; Parks, B.; Parsons, J.; Partridge, R.; Parua, N.; Pashapour, S.; Patrick, J.; Patwa, A.; Pauletta, G.; Paulini, M.; Paus, C.; Peiffer, T.; Pellett, D. E.; Penning, B.; Penzo, A.; Perfilov, M.; Peters, K.; Peters, Y.; Petrillo, G.; Pétroff, P.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Piegaia, R.; Pinera, L.; Piper, J.; Pitts, K.; Plager, C.; Pleier, M.-A.; Podesta-Lerma, P. L. M.; Podstavkov, V. M.; Pol, M.-E.; Polozov, P.; Pondrom, L.; Popov, A. V.; Potamianos, K.; Poukhov, O.; Prewitt, M.; Price, D.; Prokoshin, F.; Pronko, A.; Protopopescu, S.; Ptohos, F.; Pueschel, E.; Punzi, G.; Pursley, J.; Qian, J.; Quadt, A.; Quinn, B.; Rademacker, J.; Rahaman, A.; Ramakrishnan, V.; Rangel, M. S.; Ranjan, K.; Ranjan, N.; Ratoff, P. N.; Razumov, I.; Redondo, I.; Renkel, P.; Renton, P.; Renz, M.; Rescigno, M.; Rich, P.; Richter, S.; Rijssenbeek, M.; Rimondi, F.; Ripp-Baudot, I.; Ristori, L.; Rizatdinova, F.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Rominsky, M.; Roser, R.; Rossi, M.; Rossin, R.; Roy, P.; Royon, C.; Rubinov, P.; Ruchti, R.; Ruiz, A.; Russ, J.; Rusu, V.; Rutherford, B.; Saarikko, H.; Safonov, A.; Safronov, G.; Sajot, G.; Sakumoto, W. K.; Sánchez-Hernández, A.; Sanders, M. P.; Sanghi, B.; Santi, L.; Sartori, L.; Sato, K.; Savage, G.; Saveliev, V.; Savoy-Navarro, A.; Sawyer, L.; Scanlon, T.; Schaile, D.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schlabach, P.; Schliephake, T.; Schlobohm, S.; Schmidt, A.; Schmidt, E. E.; Schmidt, M. A.; Schmidt, M. P.; Schmitt, M.; Schwanenberger, C.; Schwarz, T.; Schwienhorst, R.; Scodellaro, L.; Scribano, A.; Scuri, F.; Sedov, A.; Seidel, S.; Seiya, Y.; Sekaric, J.; Semenov, A.; Severini, H.; Sexton-Kennedy, L.; Sforza, F.; Sfyrla, A.; Shabalina, E.; Shalhout, S. Z.; Shary, V.; Shchukin, A. A.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shiraishi, S.; Shivpuri, R. K.; Shochet, M.; Shon, Y.; Shreyber, I.; Simak, V.; Simonenko, A.; Sinervo, P.; Sirotenko, V.; Sisakyan, A.; Skubic, P.; Slattery, P.; Slaughter, A. J.; Slaunwhite, J.; Sliwa, K.; Smirnov, D.; Smith, J. R.; Snider, F. D.; Snihur, R.; Snow, G. R.; Snow, J.; Snyder, S.; Soha, A.; Söldner-Rembold, S.; Somalwar, S.; Sonnenschein, L.; Sopczak, A.; Sorin, V.; Sosebee, M.; Soustruznik, K.; Spurlock, B.; Squillacioti, P.; Stanitzki, M.; Stark, J.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Stolin, V.; Stoyanova, D. A.; Strang, M. A.; Strauss, E.; Strauss, M.; Ströhmer, R.; Strologas, J.; Strom, D.; Strycker, G. L.; Stutte, L.; Suh, J. S.; Sukhanov, A.; Suslov, I.; Svoisky, P.; Taffard, A.; Takahashi, M.; Takashima, R.; Takeuchi, Y.; Tanaka, R.; Tanasijczuk, A.; Tang, J.; Taylor, W.; Tecchio, M.; Teng, P. K.; Thom, J.; Thome, J.; Thompson, G. A.; Thomson, E.; Tiller, B.; Tipton, P.; Titov, M.; Tkaczyk, S.; Toback, D.; Tokar, S.; Tokmenin, V. V.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Tsai, S.-Y.; Tsybychev, D.; Ttito-Guzmán, P.; Tuchming, B.; Tu, Y.; Tully, C.; Turini, N.; Tuts, P. M.; Ukegawa, F.; Unalan, R.; Uozumi, S.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; van Kooten, R.; van Leeuwen, W. M.; van Remortel, N.; Varelas, N.; Varganov, A.; Varnes, E. W.; Vasilyev, I. A.; Vataga, E.; Vázquez, F.; Velev, G.; Vellidis, C.; Verdier, P.; Vertogradov, L. S.; Verzocchi, M.; Vesterinen, M.; Vidal, M.; Vila, I.; Vilanova, D.; Vilar, R.; Vint, P.; Vogel, M.; Vokac, P.; Volobouev, I.; Volpi, G.; Wagner, P.; Wagner, R. G.; Wagner, R. L.; Wagner, W.; Wagner-Kuhr, J.; Wahl, H. D.; Wakisaka, T.; Wallny, R.; Wang, M. H. L. S.; Wang, S. M.; Warburton, A.; Warchol, J.; Waters, D.; Watts, G.; Wayne, M.; Weber, G.; Weber, M.; Weinberger, M.; Weinelt, J.; Wester, W. C., III; Wetstein, M.; White, A.; Whitehouse, B.; Whiteson, D.; Wicke, D.; Wicklund, A. B.; Wicklund, E.; Wilbur, S.; Williams, G.; Williams, H. H.; Williams, M. R. J.; Wilson, G. W.; Wilson, P.; Wimpenny, S. J.; Winer, B. L.; Wittich, P.; Wobisch, M.; Wolbers, S.; Wolfe, C.; Wolfe, H.; Wood, D. R.; Wright, T.; Wu, X.; Würthwein, F.; Wyatt, T. R.; Xie, Y.; Xu, C.; Yacoob, S.; Yagil, A.; Yamada, R.; Yamamoto, K.; Yamaoka, J.; Yang, U. K.; Yang, W.-C.; Yang, Y. C.; Yao, W. M.; Yasuda, T.; Yatsunenko, Y. A.; Ye, Z.; Yeh, G. P.; Yi, K.; Yin, H.; Yip, K.; Yoh, J.; Yoo, H. D.; Yorita, K.; Yoshida, T.; Youn, S. W.; Yu, G. B.; Yu, I.; Yu, J.; Yu, S. S.; Yun, J. C.; Zanetti, A.; Zelitch, S.; Zeng, Y.; Zhang, X.; Zhao, T.; Zheng, Y.; Zhou, B.; Zhu, J.; Zielinski, M.; Zieminska, D.; Zivkovic, L.; Zucchelli, S.
2010-07-01
We combine results from searches by the CDF and D0 collaborations for a standard model Higgs boson (H) in the process gg→H→W+W- in pp¯ collisions at the Fermilab Tevatron Collider at s=1.96TeV. With 4.8fb-1 of integrated luminosity analyzed at CDF and 5.4fb-1 at D0, the 95% confidence level upper limit on σ(gg→H)×B(H→W+W-) is 1.75 pb at mH=120GeV, 0.38 pb at mH=165GeV, and 0.83 pb at mH=200GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, we exclude at the 95% confidence level a standard-model-like Higgs boson with a mass between 131 and 204 GeV.
Kaon semileptonic decays with $N_f=2+1+1$ HISQ fermions and physical light-quark masses
Gámiz, E.; Bazavov, A.; Bernard, C.; DeTar, C.; Du, D.; El-Khadra, A. X.; Freeland, E. D.; Gottlieb, Steven; Heller, U. M.; Komijani, J.; Kronfeld, A. S.; Laiho, J.; Mackenzie, P. B.; Neil, E. T.; Primer, T.; Simone, J. N.; Sugar, R.; Toussaint, D.; Van de Water, R. S.; Zhou, Ran
2016-11-13
We discuss the reduction of errors in the calculation of the form factor $f_+^{K \\pi}(0)$ with HISQ fermions on the $N_f=2+1+1$ MILC configurations from increased statistics on some key ensembles, new data on ensembles with lattice spacings down to 0.042 fm and the study of finite-volume effects within staggered ChPT. We also study the implications for the unitarity of the CKM matrix in the first row and for current tensions with leptonic determinations of $\\vert V_{us}\\vert$.
NASA Astrophysics Data System (ADS)
Lan, Tian; Kong, Liang; Wen, Xiao-Gang
2016-10-01
We propose a systematic framework to classify (2+1)-dimensional (2+1D) fermionic topological orders without symmetry and 2+1D fermionic/bosonic topological orders with symmetry G . The key is to use the so-called symmetric fusion category E to describe the symmetry. Here, E =sRep (Z2f) describing particles in a fermionic product state without symmetry, or E =sRep (Gf) [E =Rep (G )] describing particles in a fermionic (bosonic) product state with symmetry G . Then, topological orders with symmetry E are classified by nondegenerate unitary braided fusion categories over E , plus their modular extensions and total chiral central charges. This allows us to obtain a list that contains all 2+1D fermionic topological orders without symmetry. For example, we find that, up to p +i p fermionic topological orders, there are only four fermionic topological orders with one nontrivial topological excitation: (1) the K =( -1 0 0 2) fractional quantum Hall state, (2) a Fibonacci bosonic topological order stacking with a fermionic product state, (3) the time-reversal conjugate of the previous one, and (4) a fermionic topological order with chiral central charge c =1/4 , whose only topological excitation has non-Abelian statistics with spin s =1/4 and quantum dimension d =1 +√{2 } .
Chen, Zenglong; Dong, Fengshou; Xu, Jun; Liu, Xingang; Cheng, Youpu; Liu, Na; Tao, Yan; Pan, Xinglu; Zheng, Yongquan
2014-10-01
Ultraperformance convergence chromatography/tandem triple quadrupole mass spectrometry (UPC(2)-MS/MS) is a novel tool in separation science that combines the advantages of supercritical fluid chromatography with ultraperformance liquid chromatography/MS/MS technology. The use of nontoxic CO2 fluid and a postcolumn additive to complement MS/MS allows better control of analyte retention for chiral separation and high-sensitivity determination with different chiral stationary phases. This paper reports the stereoselective separation and determination of the chiral neonicotinoid sulfoxaflor in vegetables and soil by UPC(2)-MS/MS. Baseline resolution (Rs ≥ 1.56) of and high selectivity (LOQ ≤ 1.83 μg/kg) for the four stereoisomers were achieved by postcolumn addition of 1 % formic acid-methanol to a Chiralpak IA-3 using CO₂/isopropanol/acetonitrile as the mobile phase at 40 °C, 2,500 psi, and for 6.5 min in electrospray ionization positive mode. Rearranged Van't Hoff equations afforded the thermodynamic parameters ΔH (ο) and ΔS (ο), which were analyzed to promote understanding of the enthalpy-driven separation of sulfoxaflor stereoisomers. The interday mean recovery, intraday repeatability, and interday reproducibility varied from 72.9 to 103.7%, from 1.8 to 9.2%, and from 3.1 to 9.4%, respectively. The proposed method was used to study the pharmacokinetic dissipation of sulfoxaflor stereoisomers in soil under greenhouse conditions. The estimated half-life ranged from 5.59 to 6.03 d, and statistically nonsignificant enantioselective degradation was observed. This study not only demonstrates that the UPC(2)-MS/MS system is an efficient and sensitive method for sulfoxaflor stereoseparation, but also provides the first experimental evidence of the pharmacokinetic dissipation of sulfoxaflor stereoisomers in the environment.
px+ipy superfluid from s-wave interactions of fermionic cold atoms.
Zhang, Chuanwei; Tewari, Sumanta; Lutchyn, Roman M; Das Sarma, S
2008-10-17
Two-dimensional (p(x)+ip(y)) superfluids or superconductors offer a playground for studying intriguing physics such as quantum teleportation, non-Abelian statistics, and topological quantum computation. Creating such a superfluid in cold fermionic atom optical traps using p-wave Feshbach resonance is turning out to be challenging. Here we propose a method to create a p(x)+ip(y) superfluid directly from an s-wave interaction making use of a topological Berry phase, which can be artificially generated. We discuss ways to detect the spontaneous Hall mass current, which acts as a diagnostic for the chiral p-wave superfluid.
An introduction to chiral symmetry on the lattice
NASA Astrophysics Data System (ADS)
Chandrasekharan, S.; Wiese, U.-J.
2004-10-01
The SU( Nf) L⊗ SU( Nf) R chiral symmetry of QCD is of central importance for the nonperturbative low-energy dynamics of light quarks and gluons. Lattice field theory provides a theoretical framework in which these dynamics can be studied from first principles. The implementation of chiral symmetry on the lattice is a nontrivial issue. In particular, local lattice fermion actions with the chiral symmetry of the continuum theory suffer from the fermion doubling problem. The Ginsparg-Wilson relation implies Lüscher’s lattice variant of chiral symmetry which agrees with the usual one in the continuum limit. Local lattice fermion actions that obey the Ginsparg-Wilson relation have an exact chiral symmetry, the correct axial anomaly, they obey a lattice version of the Atiyah-Singer index theorem, and still they do not suffer from the notorious doubling problem. The Ginsparg-Wilson relation is satisfied exactly by Neuberger’s overlap fermions which are a limit of Kaplan’s domain wall fermions, as well as by Hasenfratz and Niedermayer’s classically perfect lattice fermion actions. When chiral symmetry is nonlinearly realized in effective field theories on the lattice, the doubling problem again does not arise. This review provides an introduction to chiral symmetry on the lattice with an emphasis on the basic theoretical framework.
Gerbaux, Pascal; De Winter, Julien; Cornil, David; Ravicini, Katia; Pesesse, Gaëlle; Cornil, Jérôme; Flammang, Robert
2008-01-01
Chiral recognition of enantiomers by host compounds is one of the most challenging topics in modern host-guest chemistry. Amongst the well-established methods, mass spectrometry (MS) is increasingly used nowadays, due to its low detection limit, short analysis time, and suitability for analyzing mixtures and for studying chiral effects in the gas phase. The development of electrospray-ionization (ESI) techniques provides an invaluable tool to study, in the gas phase, diastereoisomeric complex ions prepared from enantiomer ions and a chiral selector. This paper reports on an ESIMS and ESIMSMS study of the molecular mechanisms that intervene in the chiral-recognition phenomena observed between amino acids and a chiral crown ether. The modified crown ether, namely (+)-([18]crown-6)-2,3,11,12-tetracarboxylic acid, is used as the chiral selector when covalently bound on a stationary phase in liquid chromatography. This study was stimulated by the fact that, except with threonine and proline, consistent elution orders were observed, which indicates that the D enantiomers interact more strongly with the chiral selector than the L enantiomers. For proline, the lack of a primary amino group is likely to be responsible for the nonresolution of the two forms, whereas the second stereogenic center on threonine could explain the reversed elution order. In light of those observations, we performed mass spectrometry experiments to understand more deeply the enantiomeric recognition phenomena, both in solution by the enantiomer-labeled guest method and in the gas phase by gas-phase ligand-exchange ion/molecule reactions. The results have been further supported by quantum chemical calculations. One of the most interesting features of this work is the identification of a nonspecific interaction between proline and the crown ether upon ESIMS analysis.
Martynov, M. V. Smirnov, A. D.
2012-03-15
A gauge model featuring a chiral color symmetry of quarks was considered, and possible manifestations of this symmetry in proton-antiproton and proton-proton collisions at the Tevatron and LHC energies were studied. The cross section {sigma}{sub tt}-bar for the production of tt-bar quark pairs at the Tevatron and the forward-backward asymmetry A{sub FB}{sup pp}-bar in this process were calculated and analyzed with allowance for the contributions of the G Prime -boson predicted by the chiral color symmetry of quarks, the G Prime -boson massm{sub G Prime} and the mixing angle {theta}{sub G} being treated as free parameters of the model. Limits on m{sub G Prime} versus {theta}{sub G} were studied on the basis of data from the Tevatron on {sigma}{sub tt}-bar and A{sub FB}{sup pp}-bar, and the region compatible with these data within one standard deviation was found in the m{sub G Prime }-{theta}{sub G} plane. The region ofm{sub G Prime }-mass values that is appropriate for observing the G Prime -boson at LHC is discussed.
Shu, Irene; Alexander, Amy; Jones, Mary; Jones, Joseph; Negrusz, Adam
2016-08-15
Chiral separation is crucial for investigating methamphetamine positive cases. While (S)-(+)-enantiomer of methamphetamine (S-MAMP) is a schedule II controlled substance, (R)-(-)-enantiomer (R-MAMP) is an active ingredient of a few over-the-counter drugs in the United States. Among biological specimen types, hair provides greater detection window than blood, urine or oral fluid, and are therefore regarded with particular interest. Herein we describe a novel non-chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to directly determine methamphetamine enantiomeric composition (percentage) in hair specimens. Hair samples were washed once with acetone, powdered, incubated overnight at 53°C in 0.1M hydrochloric acid (HCl), and subjected to a solid phase extraction (SPE). The extracts were derivatized using Marfey's reagent at 53°C for 60min. The final mixture was analyzed by LC-MS/MS. Chromatographic separation was achieved using a C18 Kinetex analytical column and 60% (v/v) aqueous methanol as mobile phase (isocratic). Triple quadrupole mass spectrometer was equipped with an electro-spray ionization (ESI) source operating in negative mode and the chromatograms were acquired using a multiple-reaction monitoring (MRM) approach. The results were expressed as ratio of R- to S-MAMP and then derived to composition percentages without requiring quantitating each enantiomer. The method was precise and accurate across 0-100% S-composition at a range of 80-18,000pg/mg. The performance of the new method was compared with an (S)-(-)-N-trifluoroacetylprolyl chloride (S-TPC) derivatization and gas chromatography-mass spectrometry (GC-MS) method on authentic methamphetamine-positive hair samples. Not only the new Marfey's reagent approach presented satisfactory correlation with the S-TPC approach, but it also exhibited significantly improved quality (e.g., S/N) of the chromatograms. In summary, our protocol employs cost effective and minimally hazardous Marfey
Vector Meson Mass Corrections at O(a{sup 2}) in PQChPT with Wilson and Ginsparg-Wilson quarks
Hovhannes R. Grigoryan; Anthony W. Thomas
2005-07-01
We derive the mixed as well as unmixed lattice heavy meson chiral Lagrangian up to order O(a{sup 2}), with Wilson and Ginsparg-Wilson fermions. We consider two flavor partially quenched theory and calculate vector meson mass corrections up to order O(a{sup 2}), including the corrections associated with the violation of O(4) rotational symmetry down to hypercubic group. The chiral extrapolation formula is then compared with that used in numerical simulations.
Min Li; Huey-Wen Lin
2007-10-01
We present a preliminary calculation of the charmonium spectrum using the dynamical 2+1 flavor $24^3\\times 64$ domain wall fermion lattice configurations generated by the RBC and UKQCD collaborations. We use the relativistic heavy quark action with 3 parameters non-perturbatively determined by matching to experimental quantities. Chiral extrapolation is done on four light sea quark masses from 0.005 to 0.03, with $m_s=0.04$ and $m_{res}=0.003$. We can either predict meson masses assuming the lattice spacing is known from other methods, or calculate the lattice spacing using those quantities.
Chiral Magnetic Effect and Anomalous Transport from Real-Time Lattice Simulations
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 the amount of explicit chiral symmetry breaking due to finite quark masses.
Chiral Magnetic Effect and Anomalous Transport from Real-Time Lattice Simulations
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
Chiral Magnetic Effect and Anomalous Transport from Real-Time Lattice Simulations
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 the amount of explicit chiral symmetry breaking due to finite quark masses.
Brewer, Bobby N; Zu, Chengli; Koscho, Michael E
2005-10-01
The ability to use mixtures of deprotonated N-(3,5-dinitrobenzoyl)amino acids as chiral selectors for the determination of enantiomeric composition by electrospray ionization-mass spectrometry is demonstrated. For each experiment, two N-(3,5-dinitrobenzoyl)amino acids were chosen such that each would have opposite selectivity for the enantiomers of the analyte. Electrospray ionization-mass spectrometry, monitored in the negative ion mode, of solutions containing the two N-(3,5-dinitrobenzoyl)amino acids, sodium hydroxide, and the analyte, in a one-to-one mixture of methanol and water, afford peaks in the mass spectrum that correspond to the deprotonated 1:1 analyte-selector complexes. The ratio of the intensities of the complexes in the mass spectrum can be related to the enantiomeric composition of the analyte. Additionally, the sense and extent of chiral recognition is consistent with chromatographic observations, using chiral stationary phases derived from N-(3,5-dinitrobenzoyl)amino acids. Each analysis of enantiomeric composition requires less than 10 s to complete, indicating that this method has great potential for the development of fast-/high-throughput chiral analyses.
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.
Eom, Han Young; Kang, Myunghee; Kang, Seung Woo; Kim, Unyong; Suh, Joon Hyuk; Kim, Junghyun; Cho, Hyun-Deok; Jung, Yura; Yang, Dong-Hyug; Han, Sang Beom
2016-01-05
A method for fast chiral separation of cetirizine and quantitation of levocetirizine in human plasma using subcritical fluid chromatography with tandem mass spectrometry was developed and validated. The chromatographic separation was performed using a Chiralpak IE column (2.1 mm×150 mm, 5 μm) with an isocratic elution of CO2/organic modifier (55/45, v/v) at a flow rate of 0.85 mL/min. The organic modifier was composed of water/methanol (5/95, v/v). The makeup flow was optimized at water/methanol (10/90, v/v) and 0.2 mL/min. The most influential parameters on the separation of cetirizine affecting resolution, retention time and sensitivity were selected by fractional factorial design. The 3 selected factors were optimized by response surface methodology. Tandem mass spectrometry was used at electrospray ionization, positive ion mode, and multiple-reaction monitoring mode. Isotope-labeled cetirizine-d4 was used as the internal standard. The sample preparation of human plasma was conducted by solid phase extraction of hydrophilic-lipophilic balance (HLB) type. The developed method was validated for selectivity, linearity, precision, accuracy, recovery, limit of quantitation (LOQ), and limit of detection (LOD). The real human plasma samples were analyzed and the pharmacokinetic results were compared with results of previous research. The developed method was found to be reliable based on the similarity between the results of the current and previous methods. The chiral separation for cetirizine and economic feasibility were compared with those of previous studies using normal phase-HPLC or reversed phase-HPLC. The established analytical method could be successfully applied to pharmacokinetic study with reduction in the analysis time and costs.
Du, Jiangbo; Ma, Zhiyu; Zhang, Yifan; Wang, Ting; Chen, Xiaoyan; Zhong, Dafang
2013-12-01
A rapid, sensitive, and enantioselective method was developed and validated for determination of ornidazole enantiomers in human plasma by liquid chromatography-tandem mass spectrometry. Ornidazole enantiomers were extracted from 100μl of plasma using ethyl acetate. Baseline chiral separation (Rs=2.0) was obtained within 7.5min on a Chiral-AGP column (150mm×4.0mm, 5μm) using an isocratic mobile phase of 10mM ammonium acetate/acetic acid (100/0.01, v/v). Stable isotopically labeled R-(+)-d5-ornidazole and S-(-)-d5-ornidazole were synthesized as internal standards. Acquisition of mass spectrometric data was performed in multiple reaction monitoring mode via positive electrospray ionization, using the transitions of m/z 220→128 for ornidazole enantiomers, and m/z 225→128 for d5-ornidazole enantiomers. The method was linear in the concentration range of 0.030-10.0μg/ml for each enantiomer. The lower limit of quantification for each enantiomer was 0.030μg/ml. The relative standard deviation values of intra- and inter-day precision were 1.8-6.2% and 1.5-10.2% for R-(+)-ornidazole and S-(-)-ornidazole, respectively. The relative error values of accuracy ranged from -4.5% to 1.2% for R-(+)-ornidazole and from -5.4% to -0.8% for S-(-)-ornidazole. The validated method was successfully applied to a stereoselective pharmacokinetic study of ornidazole after oral administration of 1000mg racemic ornidazole. Copyright © 2013 Elsevier B.V. All rights reserved.
Chiral bosonization for non-commutative fields
NASA Astrophysics Data System (ADS)
Das, Ashok; Gamboa, J.; Méndez, Fernando; López-Sarrión, Justo
2004-05-01
A model of chiral bosons on a non-commutative field space is constructed and new generalized bosonization (fermionization) rules for these fields are given. The conformal structure of the theory is characterized by a level of the Kac-Moody algebra equal to (1+theta2) where theta is the non-commutativity parameter and chiral bosons living in a non-commutative fields space are described by a rational conformal field theory with the central charge of the Virasoro algebra equal to 1. The non-commutative chiral bosons are shown to correspond to a free fermion moving with a speed equal to c' = c(1+theta2)1/2 where c is the speed of light. Lorentz invariance remains intact if c is rescaled by crightarrowc'. The dispersion relation for bosons and fermions, in this case, is given by omega = c'|k|.
Liu, Yijin; Shamsi, Shahab A
2016-11-01
The sensitive detection of chiral compounds by capillary electrophoresis (CE) in biological samples remains a significant challenge and is currently considered a bottleneck in many chiral analysis projects. Chiral CE-MS can significantly improve the limit of detection and provide high sensitivity compared with chiral CE-UV. Chiral selectors such as modified cyclodextrins (CDs) and polymeric surfactants (a.k.a. molecular micelles, MoMs) in electrokinetic chromatography (EKC), micellar electrokinetic chromatography (MEKC) and capillary electrochromatography (CEC) have been developed to address the need for high sensitivity by CE-MS. However, several problems remain to be investigated to fully understand the potential of these hyphenation modes. This review provides introduction to major chiral CE-MS modes for the novice and highlights the important working principles of each mode of chiral CE-MS. Next, recent practical developments and progress in chiral CE-MS dating from January 2010 to September 2015 are described. The achievements in clinical and biomedical sciences using a variety of chiral selectors such as CDs and MoMs in EKC-MS, MEKC-MS and CEC-MS are discussed. Finally, conclusions and future prospects of CE-MS in chiral analysis are drafted.
SU(3) sextet model with Wilson fermions
NASA Astrophysics Data System (ADS)
Hansen, Martin; Drach, Vincent; Pica, Claudio
2017-08-01
We investigate the spectrum and IR properties of the SU(3) "sextet" model with two Dirac fermions in the two-index symmetric representation via lattice simulations. This model is a prime candidate for a realization of walking technicolor, which features a minimal matter content and it is expected to be inside or very close to the lower boundary of the conformal window. We use the Wilson discretization for the fermions and map the phase structure of the lattice model. We study several spectral and gradient flow observables both in the bulk and the weak coupling phases. While in the bulk phase we find clear signs of chiral symmetry breaking, in the weak coupling phase there is no clear indication for it, and instead the chiral limit of the model seems compatible with an IR-conformal behavior.
The Categorification of Fermions
NASA Astrophysics Data System (ADS)
Wang, Na; Wang, Rui; Wang, Zhi-Xi; Wu, Ke; Yang, Jie; Yang, Zi-Feng
2015-02-01
In this paper, we lift Fermions to functors acting on some homotopy category by the Boson-Fermion correspondence and get the categorified relations of Fermions. In this way, both the categorified Bosons and the categorified Fermions can be viewed as functors on the same category. We also give actions of these functors on the charged Young diagrams (or equivalently Maya diagrams), so that the classical theory of Boson-Fermion correspondence is very well recovered as a result of such a categorification.
Scaling of fat-link irrelevant-clover fermions
Zanotti, J.M.; Lasscock, B.; Leinweber, D.B.; Williams, A.G.
2005-02-01
Hadron masses are calculated in quenched lattice QCD on a variety of lattices in order to probe the scaling behavior of the Fat-Link Irrelevant Clover (FLIC) fermion action, a fat-link clover fermion action in which the purely irrelevant operators of the fermion action are constructed using APE-smeared links. The scaling analysis indicates FLIC fermions provide a new form of nonperturbative O(a) improvement where near-continuum results are obtained at finite lattice spacing.
Staggered chiral perturbation theory at next-to-leading order
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 not 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.
Critical number of fermions in three-dimensional QED
NASA Astrophysics Data System (ADS)
Gusynin, V. P.; Pyatkovskiy, P. K.
2016-12-01
Previous analytical studies of quantum electrodynamics in 2 +1 dimensions (QED3) have shown the existence of a critical number of fermions for onset of chiral symmetry breaking, the most known being the value Nc≈3.28 obtained by Nash to 1 /N2 order in the 1 /N expansion [D. Nash, Phys. Rev. Lett. 62, 3024 (1989)]. This analysis is reconsidered by solving the Dyson-Schwinger equations for the fermion propagator and the vertex to show that the more accurate gauge-independent value is Nc≈2.85 , which means that the chiral symmetry is dynamically broken for integer values N ≤2 , while for N ≥3 the system is in a chirally symmetric phase. An estimate for the value of chiral condensate ⟨ψ ¯ ψ ⟩ is given for N =2 . Knowing precise Nc would be important for comparison between continuum studies and lattice simulations of QED3.
Effective field theories for QCD with rooted staggered fermions
Bernard, Claude; Golterman, Maarten; Shamir, Yigal
2008-04-01
Even highly improved variants of lattice QCD with staggered fermions show significant violations of taste symmetry at currently accessible lattice spacings. In addition, the 'rooting trick' is used in order to simulate with the correct number of light sea quarks, and this makes the lattice theory nonlocal, even though there is good reason to believe that the continuum limit is in the correct universality class. In order to understand scaling violations, it is thus necessary to extend the construction of the Symanzik effective theory to include rooted staggered fermions. We show how this can be done, starting from a generalization of the renormalization-group approach to rooted staggered fermions recently developed by one of us. We then explain how the chiral effective theory follows from the Symanzik action, and show that it leads to 'rooted' staggered chiral perturbation theory as the correct chiral theory for QCD with rooted staggered fermions. We thus establish a direct link between the renormalization-group based arguments for the correctness of the continuum limit and the success of rooted staggered chiral perturbation theory in fitting numerical results obtained with the rooting trick. In order to develop our argument, we need to assume the existence of a standard partially-quenched chiral effective theory for any local partially-quenched theory. Other technical, but standard, assumptions are also required.
Commutator of gauge generators in non-abelian chiral theory
NASA Astrophysics Data System (ADS)
Jo, S.
1985-09-01
Commutators among non-abelian fermion currents are calculated using the BJL limit. The relation between the covariant seagull and the gauge dependence of the fermion current is derived for a canonical non-abelian theory using the path integral formulation. We observe that in a non-abelian theory with coupling to chiral fermions this relation is violated and this produces a non-trivial commutator of gauge group generators.
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.
Scalar meson spectroscopy with lattice staggered fermions
Bernard, Claude; DeTar, Carleton; Fu Ziwen; Prelovsek, Sasa
2007-11-01
With sufficiently light up and down quarks the isovector (a{sub 0}) and isosinglet (f{sub 0}) scalar meson propagators are dominated at large distance by two-meson states. In the staggered-fermion formulation of lattice quantum chromodynamics, taste-symmetry breaking causes a proliferation of two-meson states that further complicates the analysis of these channels. Many of them are unphysical artifacts of the lattice approximation. They are expected to disappear in the continuum limit. The staggered-fermion fourth-root procedure has its purported counterpart in rooted staggered chiral perturbation theory (rS{chi}PT). Fortunately, the rooted theory provides a strict framework that permits the analysis of scalar meson correlators in terms of only a small number of low-energy couplings. Thus the analysis of the point-to-point scalar meson correlators in this context gives a useful consistency check of the fourth-root procedure and its proposed chiral realization. Through numerical simulation we have measured correlators for both the a{sub 0} and f{sub 0} channels in the 'Asqtad' improved staggered-fermion formulation in a lattice ensemble with lattice spacing a=0.12 fm. We analyze those correlators in the context of rS{chi}PT and obtain values of the low-energy chiral couplings that are reasonably consistent with previous determinations.
Wilson fermions at finite temperature
Creutz, M.
1996-09-17
The author conjectures on the phase structure expected for lattice gauge theory with two flavors of Wilson fermions, concentrating on large values of the hopping parameter. Numerous phases are expected, including the conventional confinement and deconfinement phases, as well as an Aoki phase with spontaneous breaking of flavor and parity and a large hopping phase corresponding to negative quark masses.
Phenomenology of strongly coupled chiral gauge theories
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
Nagy, Tibor; Kuki, Ákos; Antal, Borbála; Nagy, Lajos; Purgel, Mihály; Sipos, Attila; Nagy, Miklós; Zsuga, Miklós; Kéki, Sándor
2015-01-01
Energy-dependent collision-induced dissociation (CID) of the dimers [2 M + Cat](+) of the noscapine and hydrastine stereoisomers was studied where Cat stands for Li(+), Na(+), K(+) and Cs(+) ions. These dimers were generated 'in situ' from the electrosprayed solution. The survival yield (SY) method was used for distinguishing the noscapine and hydrastine dimers. Significant differences were found between the characteristic collision energies (CE50, i.e. the collision energy necessary to obtain 50% fragmentation) of the homo- (R,R; S,S) and heterochiral (R,S; S,R) stereoisomers. To distinguish the enantiomer pairs L-, D-tyrosine ([M + Tyr + Cat](+)) and L-, D-lysine ([M + Lys + Cat](+)) were used as chiral selectors. Furthermore, these heterodimers [M + amino acid + Cat](+) were also applied to determine the stereoisomeric composition. It was found that the characteristic collision energy (CE50) of the noscapine and hydrastine homodimers ([2 M + Cat](+)) was inversely proportional to the ionic radius of the cations. Furthermore, the structures of the dimers [2 M + Cat](+) were studied by high level quantum chemical calculations.
Magnetic Moments of Delta and Omega- baryons with dynamical clover fermions
Aubin, Christopher; Orginos, Konstantinos; Pascalutsa, Vladimir; Vanderhaeghen, Marc
2009-01-01
We calculate the magnetic dipole moment of the Delta(1232) and Omega- baryons with 2+1-flavors of clover fermions on anisotropic lattices using a background magnetic field. This is the first dynamical calculation of these magnetic moments using a background field technique. The calculation for Omega- is done at the physical strange quark mass, with the result in units of the physical nuclear magneton Âµ_(Omega-) = -1.93(8)(12) (where the first error is statistical and the second is systematic) compared to the experimental number: -2.02(5). The Delta has been studied at three unphysical quark masses, corresponding to pion mass 366, 438, and 548 MeV. The pion-mass dependence is compared with the behavior obtained from chiral effective-field theory.
Applications of chiral symmetry
Pisarski, R.D.
1995-03-01
The author discusses several topics in the applications of chiral symmetry at nonzero temperature. First, where does the rho go? The answer: up. The restoration of chiral symmetry at a temperature T{sub {chi}} implies that the {rho} and a{sub 1} vector mesons are degenerate in mass. In a gauged linear sigma model the {rho} mass increases with temperature, m{sub {rho}}(T{sub {chi}}) > m{sub {rho}}(0). The author conjectures that at T{sub {chi}} the thermal {rho} - a{sub 1}, peak is relatively high, at about {approximately}1 GeV, with a width approximately that at zero temperature (up to standard kinematic factors). The {omega} meson also increases in mass, nearly degenerate with the {rho}, but its width grows dramatically with temperature, increasing to at least {approximately}100 MeV by T{sub {chi}}. The author also stresses how utterly remarkable the principle of vector meson dominance is, when viewed from the modern perspective of the renormalization group. Secondly, he discusses the possible appearance of disoriented chiral condensates from {open_quotes}quenched{close_quotes} heavy ion collisions. It appears difficult to obtain large domains of disoriented chiral condensates in the standard two flavor model. This leads to the last topic, which is the phase diagram for QCD with three flavors, and its proximity to the chiral critical point. QCD may be very near this chiral critical point, and one might thereby generated large domains of disoriented chiral condensates.
Taujenis, Lukas; Olšauskaitė, Vilma; Padarauskas, Audrius
2014-11-19
High-performance liquid chromatography on a glycopeptide antibiotic teicoplanin-based chiral stationary phase coupled with tandem mass spectrometry was developed for fast and reliable enantioseparation and determination of protein amino acids in hydrolyzed fertilizer samples. The effect of the mobile phase parameters (type and content of organic modifier and pH) and the column temperature on the enantioselectivity was investigated. Under optimized conditions, the majority (15 of 19) of d/l-amino acid pairs were resolved with a resolution factor (Rs) higher than 1.5 with a run time of 15 min. A triple quadrupole tandem mass spectrometer operating in multiple reaction monitoring mode with an electrospray ionization (ESI) ion source was employed for detection. The method was validated in terms of linearity, limits of detection, limits of quantitation, precision, and accuracy. Linear responses were obtained with determination coefficients higher than 0.998 for all analytes, and limits of detection were from 0.04 to 0.24 μg/mL. Sample spike/recovery experiments gave recovery values ranging from 73% for d-threonine to 116% for L-tryptophan. Relative standard deviations for inter- and intraday precision experiments were lower than 21.7%. The developed method was successfully applied for determination of the free amino acid enantiomers in five commercially available hydrolyzed protein fertilizer samples.
Low-energy couplings of QCD from current correlators near the chiral limit
NASA Astrophysics Data System (ADS)
Giusti, L.; Hernandez, P.; Laine, M.; Weisz, P.; Wittig, H.
2004-04-01
We investigate a new numerical procedure to compute fermionic correlation functions at very small quark masses. Large statistical fluctuations, due to the presence of local ``bumps'' in the wave functions associated with the low-lying eigenmodes of the Dirac operator, are reduced by an exact low-mode averaging. To demonstrate the feasibility of the technique, we compute the two-point correlator of the left-handed vector current with Neuberger fermions in the quenched approximation, for lattices with a linear extent of L approx 1.5 fm, a lattice spacing a approx 0.09 fm, and quark masses down to the epsilon-regime. By matching the results with the corresponding (quenched) chiral perturbation theory expressions, an estimate of (quenched) low-energy constants can be obtained. We find agreement between the quenched values of F extrapolated from the p-regime and extracted in the epsilon-regime.
Aaltonen, T.; Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Adelman, J.; Aguilo, E.; Alexeev, G.D.; Alkhazov, G.; /Helsinki Inst. of Phys. /Dubna, JINR /Oklahoma U. /Michigan State U. /Tata Inst. /Illinois U., Chicago /Florida State U. /Chicago U., EFI /Simon Fraser U. /York U., Canada /St. Petersburg, INP /Illinois U., Urbana /Sao Paulo, IFT /Munich U. /University Coll. London /Oxford U. /St. Petersburg, INP /Duke U. /Kyungpook Natl. U. /Chonnam Natl. U. /Florida U. /Osaka City U.
2010-05-01
We combine results from searches by the CDF and D0 collaborations for a standard model Higgs boson (H) in the process gg {yields} H {yields} W{sup +}W{sup -} in p{bar p} collisions at the Fermilab Tevatron Collider at {radical}s = 1.o6 TeV. With 4.8 fb{sup -1} of itnegrated luminosity analyzed at CDF and 5.4 fb{sup -1} at D0, the 95% Confidence Level upper limit on {sigma}(gg {yields} H) x {Beta}(H {yields} W{sup +}W{sup -}) is 1.75 pb at m{sub H} = 120 GeV, 0.38 pb at m{sub H} = 165 GeV, and 0.83 pb at m{sub H} = 200 GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, they exclude at the 95% Confidence Level a standard-model-like Higgs boson with a mass between 131 and 204 Gev.
Aaltonen, T.; Mehtala, P.; Orava, R.; Osterberg, K.; Saarikko, H.; Remortel, N. van; Abazov, V. M.; Alexeev, G. D.; Artikov, A.; Budagov, J.; Chokheli, D.; Glagolev, V.; Golovanov, G.; Kharzheev, Y. N.; Malyshev, V. L.; Poukhov, O.; Prokoshin, F.; Semenov, A.; Simonenko, A.; Sisakyan, A.
2010-07-01
We combine results from searches by the CDF and D0 collaborations for a standard model Higgs boson (H) in the process gg{yields}H{yields}W{sup +}W{sup -} in pp collisions at the Fermilab Tevatron Collider at {radical}(s)=1.96 TeV. With 4.8 fb{sup -1} of integrated luminosity analyzed at CDF and 5.4 fb{sup -1} at D0, the 95% confidence level upper limit on {sigma}(gg{yields}H)xB(H{yields}W{sup +}W{sup -}) is 1.75 pb at m{sub H}=120 GeV, 0.38 pb at m{sub H}=165 GeV, and 0.83 pb at m{sub H}=200 GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, we exclude at the 95% confidence level a standard-model-like Higgs boson with a mass between 131 and 204 GeV.
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.
Mobius domain-wall fermions on gradient-flowed dynamical HISQ ensembles
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
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.
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].
p{sub x}+ip{sub y} Superfluid from s-Wave Interactions of Fermionic Cold Atoms
Zhang Chuanwei; Tewari, Sumanta; Lutchyn, Roman M.; Das Sarma, S.
2008-10-17
Two-dimensional (p{sub x}+ip{sub y}) superfluids or superconductors offer a playground for studying intriguing physics such as quantum teleportation, non-Abelian statistics, and topological quantum computation. Creating such a superfluid in cold fermionic atom optical traps using p-wave Feshbach resonance is turning out to be challenging. Here we propose a method to create a p{sub x}+ip{sub y} superfluid directly from an s-wave interaction making use of a topological Berry phase, which can be artificially generated. We discuss ways to detect the spontaneous Hall mass current, which acts as a diagnostic for the chiral p-wave superfluid.
Is the Composite Fermion a Dirac Particle?
NASA Astrophysics Data System (ADS)
Son, Dam Thanh
2015-07-01
We propose a particle-hole symmetric theory of the Fermi-liquid ground state of a half-filled Landau level. This theory should be applicable for a Dirac fermion in the magnetic field at charge neutrality, as well as for the ν =1/2 quantum Hall ground state of nonrelativistic fermions in the limit of negligible inter-Landau-level mixing. We argue that when particle-hole symmetry is exact, the composite fermion is a massless Dirac fermion, characterized by a Berry phase of π around the Fermi circle. We write down a tentative effective field theory of such a fermion and discuss the discrete symmetries, in particular, C P . The Dirac composite fermions interact through a gauge, but non-Chern-Simons, interaction. The particle-hole conjugate pair of Jain-sequence states at filling factors n /(2 n +1 ) and (n +1 )/(2 n +1 ) , which in the conventional composite fermion picture corresponds to integer quantum Hall states with different filling factors, n and n +1 , is now mapped to the same half-integer filling factor n +1/2 of the Dirac composite fermion. The Pfaffian and anti-Pfaffian states are interpreted as d -wave Bardeen-Cooper-Schrieffer paired states of the Dirac fermion with orbital angular momentum of opposite signs, while s -wave pairing would give rise to a particle-hole symmetric non-Abelian gapped phase. When particle-hole symmetry is not exact, the Dirac fermion has a C P -breaking mass. The conventional fermionic Chern-Simons theory is shown to emerge in the nonrelativistic limit of the massive theory.
NGN, QCD2 and chiral phase transition from string theory
NASA Astrophysics Data System (ADS)
Gao, Yi-hong; Xu, Weishui; Zeng, Ding-fang
2006-08-01
We construct a D2-D8-bar D8 configuration in string theory, it can be described at low energy by two dimensional field theory. In the weak coupling region, the low energy theory is a nonlocal generalization of Gross-Neveu(GN) model which dynamically breaks the chiral flavor symmetry U(Nf)L × U(Nf)R at large Nc and finite Nf. However, in the strong coupling region, we can use the SUGRA/Born-Infeld approximation to describe the low energy dynamics of the system. Also, we analyze the low energy dynamics about the configuration of wrapping the one direction of D2 brane on a circle with anti-periodic boundary condition of fermions. The fermions and scalars on D2 branes get mass and decouple from the low energy theory. The IR dynamics is described by the QCD2 at weak coupling. In the opposite region, the dynamics has a holographic dual description. And we have discussed the phase transition of chiral symmetry breaking at finite temperature. Finally, after performing T-duality, this configuration is related to some other brane configurations.
Gritti, Fabrice; Guiochon, Georges
2014-01-31
The mechanism of mass transfer was studied on a cellulose-based chiral stationary phase (CSP, Lux Cellulose-1) using aqueous mixtures of acetonitrile (50/50-90/10, v/v) or methanol (90/10 and 100/0, v/v) as the mobile phase. An experimental protocol validated in RPLC and HILIC chromatography and recently extended to chiral RPLC was applied. The five mass-transfer contributions (longitudinal diffusion, short-range and long-range eddy dispersion, solid-liquid mass transfer resistances due to finite intra-particle diffusivity and slow adsorption-desorption) to the reduced height equivalent to a theoretical plate (HETP) were measured. The experimental results show that the adsorption rate constants kads of trans-stilbene enantiomers onto the CSP are three times larger with acetonitrile than with methanol as the organic modifier. This is correlated to the decrease of enantioselectivity from 1.4 (in methanol) to only 1.1 (in acetonitrile). The amount of solvent needed to achieve a separation factor of exactly 2.0 was determined. This showed that analysis cost could be reduced seven times by selecting pure methanol as the eluent for a 5cm long column rather than an acetonitrile-water mixture for a longer (20-45cm) column.
Chiral Lagrangian parameters for scalar and pseudoscalar mesons
NASA Astrophysics Data System (ADS)
Bardeen, W.; Eichten, E.; Thacker, H.
2004-03-01
The results of a high-statistics study of scalar and pseudoscalar meson propagators in quenched lattice QCD are presented. For two values of lattice spacing, β=5.7 (a≈.18 fm) and 5.9 (a≈.12 fm), we probe the light quark mass region using clover improved Wilson fermions with the modified quenched approximation pole-shifting ansatz to treat the exceptional configuration problem. The quenched chiral loop parameters m0 and αΦ are determined from a study of the pseudoscalar hairpin correlator. From a global fit to the meson correlators, estimates are obtained for the relevant chiral Lagrangian parameters, including the Leutwyler parameters L5 and L8. Using the parameters obtained from the singlet and nonsinglet pseudoscalar correlators, the quenched chiral loop (QCL) effect in the nonsinglet scalar meson correlator is studied. By removing this QCL effect from the lattice correlator, we obtain the mass and decay constant of the ground state scalar, isovector meson a0.
Polar Kerr effect studies of time reversal symmetry breaking states in heavy fermion superconductors
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 ^{3}He-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.
Polar Kerr effect studies of time reversal symmetry breaking states in heavy fermion superconductors
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.
Polar Kerr effect studies of time reversal symmetry breaking states in heavy fermion superconductors
NASA Astrophysics Data System (ADS)
Schemm, E. R.; Levenson-Falk, E. M.; Kapitulnik, A.
2017-04-01
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. 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. Here 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.
Fate of pion condensation in quark matter: From the chiral limit to the physical pion mass
Abuki, H.; Anglani, R.; Pellicoro, M.; Ruggieri, M.; Gatto, R.
2009-02-01
We study aspects of the pion condensation in two-flavor neutral quark matter using the Nambu-Jona-Lasinio model of QCD at finite density. We investigate the role of electric charge neutrality, and explicit symmetry breaking via quark mass, both of which control the onset of the charged pion ({pi}{sup c}) condensation. We show that the equality between the electric chemical potential and the in-medium pion mass, {mu}{sub e}=M{sub {pi}{sup -}}, as a threshold, persists even for a composite pion system in the medium, provided the transition to the pion condensed phase is of the second order. Moreover, we find that the pion condensate in neutral quark matter is extremely fragile with respect to the symmetry breaking effect via a current quark mass m, and is ruled out for m larger than the order of 10 keV.
Li, Xiangtan; McCullum, Cassandra; Zhao, Shulin; Hu, Hankun; Liu, Yi-Ming
2015-01-01
Previous work has established that D-serine (D-Ser) plays important roles in certain neurological processes. Study on its uptake /storage and release by neuronal cells is highly significant for elucidating relevant mechanisms. In this work, PC-12 cells were incubated with racemic Ser (100 µM each enantiomer). After incubation, both intra- and extracellular levels of D-Ser and L-Ser were quantified by chiral microchip electrophoresis with mass spectrometric detection. It was found the cells preferably took up D-Ser over L-Ser. After 120 min incubation, D-Ser percentage ([D-Ser] /([D-Ser]+[L-Ser]) in the culture media changed from 50% to 9% while inside the cells it increased from 13% to 67%. Small neutral amino acids such as threonine impaired D-Ser uptake. Ser release was studied by using PC-12 cells preloaded with D-Ser. KCl, Glu, and Gly evoked Ser release. Interestingly, while depolarization by KCl evoked release of Ser as a D-Ser : L-Ser mixture of 1:1 ratio, the stereoisomeric composition of Ser released due to Glu exposure varied with the exposure time, ranging from 73% D-Ser (i.e. [D-Ser] > [L-Ser]) at 2 min to 44% (i.e. [D-Ser] < [L-Ser]) at 14 min, clearly indicating a stereochemical preference for D-Ser in Ser release from neuronal cells evoked by Glu-receptor activation. PMID:25611520
Sun, Luning; Cao, Yang; Jiao, Huiwen; Fang, Yunqian; Yang, Zhicheng; Bian, Mingliang; Zhang, Hongwen; Gong, Xiaojian; Wang, Yongqing
2015-11-01
A simple and enantioselective method was developed and validated for the simultaneous determination of (R)- and (S)-lansoprazole in human plasma by chiral liquid chromatography with tandem mass spectrometry. Lansoprazole enantiomers and internal standard (esomeprazole) were extracted from plasma using acetonitrile as protein precipitating agent. Baseline chiral separation was achieved within 9.0 min on a Chiralpak IC column (150 mm × 4.6 mm, 5 μm) with the column temperature of 30°C. The mobile phase consisted of 10 mM ammonium acetate solution containing 0.05% acetic acid/acetonitrile (50:50, v/v). The mass spectrometric analysis was performed using a QTrap 5500 mass spectrometer coupled with an electrospray ionization source in positive ion mode. The multiple reactions monitoring transitions of m/z 370.1→252.1 and 346.1→198.1 were used to quantify lansoprazole enantiomers and esomeprazole, respectively. For each enantiomer, no apparent matrix effect was found, the calibration curve was linear over 5.00-3000 ng/mL, the intra- and inter-day precisions were below 10.0%, and the accuracy was -3.8 to 3.3%. Analytes were stable during the study. No chiral inversion was observed during sample storage, preparation procedure and analysis. The method was applied to the stereoselective pharmacokinetic studies in human after intravenous administration of dexlansoprazole or racemic lansoprazole.
Li, Yuanbo; Dong, Fengshou; Liu, Xingang; Xu, Jun; Li, Jing; Kong, Zhiqiang; Chen, Xiu; Liang, Xuyang; Zheng, Yongquan
2012-02-10
The manuscript concerns the development and validation of a novel and sensitive multi-residue method for simultaneous enantiomeric analysis of 8 triazole fungicides (tetraconazole, fenbuconazole, epoxiconazole, diniconazole, hexaconazole, triadimefon, paclobutrazol, and myclobutanil) in soil and water using chiral liquid chromatography coupled with tandem mass spectrometry. The separation and determination were performed using reversed-phase chromatography on a cellulose chiral stationary phase, a Chiralcel OD-RH (150 mm × 4.6 mm) column, under isocratic conditions using a mixture of ACN-2 mM ammonium acetate in water (55/45, v/v) as the mobile phase at 0.45 mL/min flow rate. The effects of three cellulose-based columns and three amylose-based columns on the separation were also investigated. The QuEChERS (acronym for quick, easy, cheap, effective, rugged and safe) method and solid-phase extraction (SPE) were used for the extraction and clean-up of the soil and water samples, respectively. Parameters including the matrix effect, linearity, precision, accuracy and stability were undertaken. Under optimal conditions, the mean recoveries for all sixteen enantiomers from the soil samples were 76.4-108.1% with 2.6-12.0% intra-day relative standard deviations (RSD) and 4.2-14.1% inter-day RSD at 5, 25 and 50 μg/kg levels; the mean enantiomer recoveries from the water samples were 81.2-106.5% with 2.1-11.5% intra-day RSD and 3.4-13.6% inter-day RSD at 0.25, 0.5 and 2.5 μg/L levels. Coefficients of determination R2 ≥ 0.9989 were achieved for all studied analytes in the soil and water matrix calibration curves within the range of 1.0-125 μg/L. The limits of detection (LOD) (S/N=3) for all enantiomers in the soil and water were less than 1.0 μg/kg or μg/L, whereas the limit of quantification (LOQ) (S/N=10) did not exceed 3.0 μg/kg or μg/L. The results of the method validation confirm that this proposed method is convenient and reliable for the enantioselective
Chiral magnetic effect in a lattice model
NASA Astrophysics Data System (ADS)
Feng, Bo; Hou, De-fu; Liu, Hui; Ren, Hai-cang; Wu, Ping-ping; Wu, Yan
2017-06-01
We study analytically the one-loop contribution to the chiral magnetic effect (CME) using lattice regularization with a Wilson fermion field. In the continuum limit, we find that the chiral magnetic current vanishes at nonzero temperature but emerges at zero temperature consistent with that found by Pauli-Villas regularization. For finite lattice size, however, the chiral magnetic current is nonvanishing at nonzero temperature. But the numerical value of the coefficient of CME current is very small compared with that extracted from the full QCD simulation for the same lattice parameters. The possibility of higher-order corrections from QCD dynamics is also assessed.
NASA Astrophysics Data System (ADS)
Petitjean, Michel
2002-08-01
An index evaluating the amount of chirality of a mixture of colored random variables is defined. Properties are established. Extreme chiral mixtures are characterized and examples are given. Connections between chirality, Wasserstein distances, and least squares Procrustes methods are pointed out.
Camacho-Muñoz, Dolores; Kasprzyk-Hordern, Barbara
2015-12-01
Enantiomeric profiling of chiral pharmacologically active compounds (PACs) in the environment has hardly been investigated. This manuscript describes, for the first time, a multi-residue enantioselective method for the analysis of human and veterinary chiral PACs and their main metabolites from different therapeutic groups in complex environmental samples such as wastewater and river water. Several analytes targeted in this paper have not been analysed in the environment at enantiomeric level before. These are aminorex, carboxyibuprofen, carprofen, cephalexin, 3-N-dechloroethylifosfamide, 10,11-dihydro-10-hydroxycarbamazepine, dihydroketoprofen, fenoprofen, fexofenadine, flurbiprofen, 2-hydroxyibuprofen, ifosfamide, indoprofen, mandelic acid, 2-phenylpropionic acid, praziquantel and tetramisole. The method is based on chiral liquid chromatography utilising a chiral α1-acid glycoprotein column and tandem mass spectrometry detection. Excellent chromatographic separation of enantiomers (Rs≥1.0) was achieved for chloramphenicol, fexofenadine, ifosfamide, naproxen, tetramisole, ibuprofen and their metabolites: aminorex and dihydroketoprofen (three of four enantiomers), and partial separation (Rs = 0.7-1.0) was achieved for ketoprofen, praziquantel and the following metabolites: 3-N-dechloroethylifosfamide and 10,11-dihydro-10-hydroxycarbamazepine. The overall performance of the method was satisfactory for most of the compounds targeted. Method detection limits were at low nanogram per litre for surface water and effluent wastewater. Method intra-day precision was on average under 20% and sample pre-concentration using solid phase extraction yielded recoveries >70% for most of the analytes. This novel, selective and sensitive method has been applied for the quantification of chiral PACs in surface water and effluent wastewater providing excellent enantioresolution of multicomponent mixtures in complex environmental samples. It will help with better understanding
Experimental Realization of Type-II Dirac Fermions in a PdTe2 Superconductor
NASA Astrophysics Data System (ADS)
Noh, Han-Jin; Jeong, Jinwon; Cho, En-Jin; Kim, Kyoo; Min, B. I.; Park, Byeong-Gyu
2017-07-01
A Dirac fermion in a topological Dirac semimetal is a quadruple-degenerate quasiparticle state with a relativistic linear dispersion. Breaking either time-reversal or inversion symmetry turns this system into a Weyl semimetal that hosts double-degenerate Weyl fermion states with opposite chiralities. These two kinds of quasiparticles, although described by a relativistic Dirac equation, do not necessarily obey Lorentz invariance, allowing the existence of so-called type-II fermions. The recent theoretical discovery of type-II Weyl fermions evokes the prediction of type-II Dirac fermions in PtSe2 -type transition metal dichalcogenides, expecting experimental confirmation. Here, we report an experimental realization of type-II Dirac fermions in PdTe2 by angle-resolved photoemission spectroscopy combined with ab initio band calculations. Our experimental finding shows the first example that has both superconductivity and type-II Dirac fermions, which turns the topological material research into a new phase.
Eberhardt, Otto; Herbert, Geoffrey; Lacker, Heiko; Lenz, Alexander; Menzel, Andreas; Nierste, Ulrich; Wiebusch, Martin
2012-12-14
We perform a comprehensive statistical analysis of the standard model (SM) with three and four generations using the latest Higgs search results from LHC and Tevatron, the electroweak precision observables measured at LEP and SLD, and the latest determinations of M(W), m(t), and α(s). For the three-generation case we analyze the tensions in the electroweak fit by removing individual observables from the fit and comparing their predicted values with the measured ones. In particular, we discuss the impact of the Higgs search results on the deviations of the electroweak precision observables from their best-fit values. Our indirect prediction of the top mass is m(t) =175.7(-2.2)(+3.0) GeV at 68.3% C.L., which is in good agreement with the direct measurement. We also plot the preferred area in the M(W)-m(t) plane. The best-fit Higgs boson mass is 126.0 GeV. For the case of the SM with a perturbative sequential fourth fermion generation (SM4) we discuss the deviations of the Higgs signal strengths from their best-fit values. The H → γγ signal strength now disagrees with its best-fit SM4 value at more than 4σ. We perform a likelihood-ratio test to compare the SM and SM4 and show that the SM4 is excluded at 5.3σ. Without the Tevatron data on H → bb the significance drops to 4.8σ.
Gonzalez-Lopez, Jennifer; Jansen, Karl; Renner, Dru B.; Shindler, Andrea
2013-02-01
The use of chirally rotated boundary conditions provides a formulation of the Schroedinger functional that is compatible with automatic O(a) improvement of Wilson fermions up to O(a) boundary contributions. The elimination of bulk O(a) effects requires the non-perturbative tuning of the critical mass and one additional boundary counterterm. We present the results of such a tuning in a quenched setup for several values of the renormalized gauge coupling, from perturbative to non-perturbative regimes, and for a range of lattice spacings. We also check that the correct boundary conditions and symmetries are restored in the continuum limit.
D. J. Antonio; T. Blum; K. C. Bowler; P. A. Boyle; N. H. Christ; S. D. Cohen; M. A. Clark; C. Dawson; A. Hart; K. Hashimoto; T. Izubuchi; B. Joó; C. Jung; A. D. Kennedy; R. D. Kenway; S. Li; H. W. Lin; M.F. Lin; R. D. Mawhinney; C.M. Maynard; J. Noaki; S. Ohta; S. Sasaki; A. Soni; R. J. Tweedie; A. Yamaguchi
2007-06-01
We present results for the static interquark potential, light meson and baryon masses, and light pseudoscalar meson decay constants obtained from simulations of domain wall QCD with one dynamical flavour approximating the $s$ quark, and two degenerate dynamical flavours with input bare masses ranging from $m_s$ to $m_s/4$ approximating the $u$ and $d$ quarks. We compare these quantities obtained using the Iwasaki and DBW2 improved gauge actions, and actions with larger rectangle coefficients, on $16^3\\times32$ lattices. We seek parameter values at which both the chiral symmetry breaking residual mass due to the finite lattice extent in the fifth dimension and the Monte Carlo time history for topological charge are acceptable for this set of quark masses at lattice spacings above 0.1 fm. We find that the Iwasaki gauge action is best, demonstrating the feasibility of using QCDOC to generate ensembles which are good representations of the QCD path integral on lattices of up to 3 fm in spatial extent with lattice spacings in the range 0.09-0.13 fm. Despite large residual masses and a limited number of sea quark mass values with which to perform chiral extrapolations, our results for light hadronic physics scale and agree with experimental measurements within our statistical uncertainties.
Factorization of fermion doubles on the lattice
NASA Astrophysics Data System (ADS)
de A. Bicudo, P. J.
2000-04-01
We address the problem of the fermion species doubling on the Lattice. Our strategy is to factorize the fermion doubles from the action. The mass term of the Dirac-Wilson action is changed. In this case the extra roots which appear in the action of free fermions in the moment representation are independent of the mass and can be factorized from the fermion propagator. However the gauge couplings suffer from the pathological ghost poles which are common to non-local actions. This action can be used to find a solution of the Ginsparg Wilson relation, which is cured from the non-local pathology. Finally we compare this factorized action with solutions of The Ginsparg Wilson relation. We find that the present is equivalent to the Zenkin action, and that it is not exponentially local, in contrast with Neuberger's action.
NASA Astrophysics Data System (ADS)
Khan, Saki
2016-06-01
We present a minimal renormalizable non-supersymmetric S O(10) grand unified model with a symmetry breaking sector consisting of Higgs fields in the 54H + 126H + 10H representations. This model admits a single intermediate scale associated with Pati-Salam symmetry along with a discrete parity. Spontaneous symmetry breaking, the unification of gauge couplings and proton lifetime estimates are studied in detail in this framework. Including threshold corrections self-consistently, obtained from a full analysis of the Higgs potential, we show that the model is compatible with the current experimental bound on proton lifetime. The model generally predicts an upper bound of few times 1035 yrs for proton lifetime, which is not too far from the present Super-Kamiokande limit of τp ≳ 1.29 × 1034 yrs. With the help of a Pecci-Quinn symmetry and the resulting axion, the model provides a suitable dark matter candidate while also solving the strong CP problem. The intermediate scale, MI ≈ (1013 - 1014) GeV which is also the B - L scale, is of the right order for the right-handed neutrino mass which enables a successful description of light neutrino masses and oscillations. The Yukawa sector of the model consists of only two matrices in family space and leads to a predictive scenario for quark and lepton masses and mixings. The branching ratios for proton decay are calculable with the leading modes being p → e+π0 and p →v ¯π+ . Even though the model predicts no new physics within the reach of LHC, the next generation proton decay detectors and axion search experiments have the capability to pass verdict on this minimal scenario.
Fukugita, M. ); Mino, H. ); Okawa, M. , Ibaraki 305 ); Ukawa, A. )
1990-10-15
A previous finite-size study for the chiral phase transition of two-flavor QCD is extended to a smaller quark mass of {ital m}{sub {ital q}}=0.0125 in lattice units. The characteristics of the system for lattice sizes (6{sup 3}--12{sup 3}){times}4 are found to be quite similar to those for {ital m}{sub {ital q}}=0.025. The increase of susceptibilities over this range of the spatial size is still too mild to discriminate among the order of the transition also at this small quark mass.
Chiral anomalies in the reduced model
NASA Astrophysics Data System (ADS)
Kikukawa, Yoshio; Suzuki, Hiroshi
2002-09-01
On the basis of an observation due to Kiskis, Narayanan and Neuberger, we show that there is a remnant of chiral anomalies in the reduced model when a Dirac operator which obeys the Ginsparg-Wilson relation is employed for the fermion sector. We consider fermions belonging to the fundamental representation of the gauge group U(N) or SU(N). For vector-like theories, we determine a general form of the axial anomaly or the topological charge within a framework of a U(1) embedding. For chiral gauge theories with the gauge group U(N), a remnant of gauge anomaly emerges as an obstruction to a smooth fermion integration measure. The pure gauge action of gauge-field configurations which cause these non-trivial phenomena always diverges in the 't Hooft N→∞ limit when d > 2.
Chirality and gravitational parity violation.
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.
Chiral magnetic effect in condensed matter systems
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
Chiral superfluidity with p-wave symmetry from an interacting s-wave atomic Fermi gas.
Liu, Bo; Li, Xiaopeng; Wu, Biao; Liu, W Vincent
2014-09-30
Chiral p-wave superfluids are fascinating topological quantum states of matter that have been found in the liquid (3)He-A phase and arguably in the electronic Sr2RuO4 superconductor. They are fundamentally related to the fractional 5/2 quantum Hall state, which supports fractional exotic excitations. Past studies show that they require spin-triplet pairing of fermions by p-wave interaction. Here we report that a p-wave chiral superfluid state can arise from spin-singlet pairing for an s-wave interacting atomic Fermi gas in an optical lattice. This p-wave state is conceptually distinct from all previous conventional p-wave states as it is for the centre-of-mass motion, instead of the relative motion. It leads to spontaneous generation of angular momentum, finite Chern numbers and topologically protected chiral fermionic zero modes bounded to domain walls, all occuring at a higher critical temperature in relative scales. Signature quantities are predicted for the cold atom experimental condition.
Designer Dirac Fermions, Topological Phases, and Gauge Fields in Molecular Graphene
NASA Astrophysics Data System (ADS)
Manoharan, Hari C.
2013-03-01
The observation of massless Dirac fermions in monolayer graphene has propelled a new area of science and technology seeking to harness charge carriers that behave relativistically within solid-state materials. Using low-temperature scanning tunneling microscopy and spectroscopy, we show the emergence of Dirac fermions in a fully tunable condensed-matter system--molecular graphene--assembled via atomic manipulation of a conventional two-dimensional electron system in a surface state. We embed, image, and tune the symmetries underlying the two-dimensional Dirac equation into these electrons by sculpting the surface potential with manipulated molecules. By distorting the effective electron hopping parameters into a Kekulé pattern, we find that these natively massless Dirac particles can be endowed with a tunable mass engendered by the associated scalar gauge field, in analogy to the Higgs field. With altered symmetry and texturing of the assembled lattices, the Dirac fermions can be dressed with gauge electric or magnetic fields such that the carriers believe they are in real fields and condense into the corresponding ground state, as confirmed by tunneling spectroscopy. Using these techniques we ultimately fabricate a quantum Hall state without breaking time-reversal symmetry, in which electrons quantize in a gauge magnetic field ramped to 60 Tesla with zero applied laboratory field. We show that these and other chiral states now possible to realize have direct analogues in topological insulators, and can be used to guide or confine charge in nontrivial ways.
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).
Dynamical symmetries for fermions
Guidry, M.
1989-01-01
An introduction is given to the Fermion Dynamical Symmetry Model (FDSM). The analytical symmetry limits of the model are then applied to the calculation of physical quantities such as ground-state masses and B(E{sub 2}) values in heavy nuclei. These comparisons with data provide strong support for a new principle of collective motion, the Dynamical Pauli Effect, and suggest that dynamical symmetries which properly account for the pauli principle are much more persistent in nuclear structure than the corresponding boson symmetries. Finally, we present an assessment of criticisms which have been voiced concerning the FDSM, and a discussion of new phenomena and exotic spectroscopy'' which may be suggested by the model. 14 refs., 8 figs., 4 tabs.
Chiral orbifold construction of field theories with extra dimensions
NASA Astrophysics Data System (ADS)
Hailu, Girma
We build higher dimensional field theories which have chiral fermion zero-modes on orbifolds. We show that orbifold boundary conditions and scalar vacuum expectation values interplay to produce chiral fermions localized on fat three branes. We develop a scheme for computing field propagators in higher dimensional theories obeying chiral orbifold boundary conditions. Using this scheme we compute the loop corrections to an effective field theory in five dimensions. We find that the renormalization group running of the higher dimensional bulk theory leads to a running of the four dimensional brane couplings. We generalize an argument to verify that the chiral anomaly that arises in these chiral orbifold theories is entirely confined on and uniformly distributed over the fixed points of the orbifold, independent of the shape of the chiral zero-modes. We construct a setup in which a scalar field with appropriate profile in the extra dimension is used to address the hierarchy problem and also localize both chiral fermions and zero-mode gravitons on the same three brane in five dimensions. We construct exact and nonpetrurbative quantum moduli spaces and dynamical superpotentials of an infinite set of linear and ring N = 1 supersymmetric moose theories with SU(2) gauge group at each node and link chiral superfields in the fundamental representation.
Masses and decay constants of D(s) * and B(s) * mesons with Nf=2 +1 +1 twisted mass fermions
NASA Astrophysics Data System (ADS)
Lubicz, V.; Melis, A.; Simula, S.; ETM Collaboration
2017-08-01
We present a lattice calculation of the masses and decay constants of D(s) * and B(s) * mesons using the gauge configurations produced by the European Twisted Mass Collaboration (ETMC) with Nf=2 +1 +1 dynamical quarks at three values of the lattice spacing a ˜(0.06 -0.09 ) fm . Pion masses are simulated in the range Mπ≃(210 - 450 ) MeV , while the strange and charm sea-quark masses are close to their physical values. We compute the ratios of vector to pseudoscalar masses and decay constants for various values of the heavy-quark mass mh in the range 0.7 mcphys≲mh≲3 mcphys . In order to reach the physical b -quark mass, we exploit the heavy quark effective theory prediction that, in the static limit of infinite heavy-quark mass, the considered ratios are equal to one. At the physical point our results are MD*/MD=1.0769 (79 ) , MDs*/MDs=1.0751(56 ), fD*/fD=1.078 (36 ), fDs*/fD s=1.087 (20 ), MB*/MB=1.0078 (15 ), MBs*/MBs=1.0083(10 ), fB*/fB=0.958 (22 ) and fBs*/fB s=0.974 (10 ). Combining them with the experimental values of the pseudoscalar meson masses (used as input to fix the quark masses) and the values of the pseudoscalar decay constants calculated by ETMC, we get MD*=2013 (14 ), MDs*=2116 (11 ), fD*=223.5 (8.4 ), fDs*=268.8 (6.6 ), MB*=5320.5 (7.6 ), MBs*=5411.36 (5.3 ), fB*=185.9 (7.2 ) and fBs*=223.1 (5.4 ) MeV .
Collective Hamiltonian for chiral modes
NASA Astrophysics Data System (ADS)
Chen, Q. B.; Zhang, S. Q.; Zhao, P. W.; Jolos, R. V.; Meng, J.
2013-02-01
A collective model is proposed to describe the chiral rotation and vibration and applied to a system with one h11/2 proton particle and one h11/2 neutron hole coupled to a triaxial rigid rotor. The collective Hamiltonian is constructed from the potential energy and mass parameter obtained in the tilted axis cranking approach. By diagonalizing the collective Hamiltonian with a box boundary condition, it is found that for the chiral rotation, the partner states become more degenerate with the increase of the cranking frequency, and for the chiral vibrations, their important roles for the collective excitation are revealed at the beginning of the chiral rotation region.
NASA Astrophysics Data System (ADS)
Tawfik, Abdel Nasser; Magdy, Niseem
2015-01-01
Effects of an external magnetic field on various properties of quantum chromodynamics (QCD) matter under extreme conditions of temperature and density (chemical potential) have been analyzed. To this end, we use SU(3) Polyakov linear-σ model and assume that the external magnetic field (e B ) adds some restrictions to the quarks' energy due to the existence of free charges in the plasma phase. In doing this, we apply the Landau theory of quantization, which assumes that the cyclotron orbits of charged particles in a magnetic field should be quantized. This requires an additional temperature to drive the system through the chiral phase transition. Accordingly, the dependence of the critical temperature of chiral and confinement phase transitions on the magnetic field is characterized. Based on this, we have studied the thermal evolution of thermodynamic quantities (energy density and trace anomaly) and the first four higher-order moment of particle multiplicity. Having all these calculations, we have studied the effects of the magnetic field on the chiral phase transition. We found that both critical temperature Tc and critical chemical potential increase with increasing magnetic field, e B . Last but not least, the magnetic effects of the thermal evolution of four scalar and four pseudoscalar meson states are studied. We concluded that the meson masses decrease as the temperature increases up to Tc. Then, the vacuum effect becomes dominant and rapidly increases with the temperature T . At low T , the scalar meson masses normalized to the lowest Matsubara frequency rapidly decrease as T increases. Then, starting from Tc, we find that the thermal dependence almost vanishes. Furthermore, the meson masses increase with increasing magnetic field. This gives a characteristic phase diagram of T vs external magnetic field e B . At high T , we find that the masses of almost all meson states become temperature independent. It is worthwhile to highlight that the various meson
Heavy fermion quantum criticality.
Nazario, Zaira; Santiago, David I
2008-09-26
During the last few years, investigations of rare-earth materials have made clear that heavy fermion quantum criticality exhibits novel physics not fully understood. In this work, we write for the first time the effective action describing the low energy physics of the system. The f fermions are replaced by a dynamical scalar field whose nonzero expected value corresponds to the heavy fermion phase. The effective theory is amenable to numerical studies as it is bosonic, circumventing the fermion sign problem. Via effective action techniques, renormalization group studies, and Callan-Symanzik resummations, we describe the heavy fermion criticality and predict the heavy fermion critical dynamical susceptibility and critical specific heat. The specific heat coefficient exponent we obtain (0.39) is in excellent agreement with the experimental result at low temperatures (0.4).
The Turbulent Chiral Magnetic Cascade in the Early Universe
NASA Astrophysics Data System (ADS)
Brandenburg, Axel; Schober, Jennifer; Rogachevskii, Igor; Kahniashvili, Tina; Boyarsky, Alexey; Fröhlich, Jürg; Ruchayskiy, Oleg; Kleeorin, Nathan
2017-08-01
The presence of asymmetry between fermions of opposite handedness in plasmas of relativistic particles can lead to exponential growth of a helical magnetic field via a small-scale chiral dynamo instability known as the chiral magnetic effect. Here, we show, using dimensional arguments and numerical simulations, that this process produces through the Lorentz force chiral magnetically driven turbulence. A {k}-2 magnetic energy spectrum emerges via inverse transfer over a certain range of wavenumbers k. The total chirality (magnetic helicity plus normalized chiral chemical potential) is conserved in this system. Therefore, as the helical magnetic field grows, most of the total chirality gets transferred into magnetic helicity until the chiral magnetic effect terminates. Quantitative results for height, slope, and extent of the spectrum are obtained. Consequences of this effect for cosmic magnetic fields are discussed.
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.
Study of Chiral Confining Model with Vector Mesons
NASA Astrophysics Data System (ADS)
Ren, Ching-Yun
1991-02-01
This dissertation consists of two parts, the study of the chiral confining model and the investigation of vacuum instability. In the first part we present a chiral confining model in which a bag is formed dynamically. The major topics addressed are: construction of the model, mean-field solution, anomalously large rho nucleon tensor coupling, and a projection method including the quantum effects of mesons. Two features of QCD, namely, chiral invariance and vacuum condensates, are crucial ingredients of our chiral confining model. The interaction of the valence quarks with the quark condensate is described via the sigma field. It generates the quark dynamical mass. The interaction of the quarks with the gluon condensate is described in our model through the color dielectric function, epsilon. This interaction generates the bag within which quarks are absolutely confined. The introduction of the color dielectric function epsilon modifies the quark-meson interaction by multiplying a factor epsilon ^{-1/2}. Thus the quark part of the rho meson source current is structurally different from the isovector part of the electromagnetic current. Thus the chiral confining model provides a natural explanation why the tensor coupling of the rho meson, kappa_rho, is larger than the isovector part of the anomalous magnetic moment of the nucleon, kappa_upsilon . We have improved a simple method of calculating expectation values of operators in states of good angular momentum projected from a hedgehog baryon state. We have included the contributions of quantum mesons. The symmetry of the hedgehog state under grand-reversal introduces remarkable simplification in the calculation of matrix elements of operators which do not contain time derivatives of meson fields. The quantum meson contributions turn out to be (3/2)/< B|{bf J }^2| B> times the classical meson fields contributions, with | B> being the hedgehog state. In the second part we show that the perturbative vacuum of model
Song, Y L; Jing, W H; Du, G; Yang, F Q; Yan, R; Wang, Y T
2014-04-18
Angular-type pyranocoumarins (APs), the derivatives of khellactone, are widely documented as the main active constituents in Peucedani Radix (Chinese name: Qian-hu). Owing to the natural occurrence of chiral centers, enantiomers of APs are extensively distributed in the original plant, and enantioselective performances have been definitely demonstrated for these enantiomers. In current study, the chemical characterization of the major and minor APs in Peucedani Radix was performed using ultra high performance liquid chromatography coupled with diode array detector and hybrid ion trap-orbitrap mass spectrometry. On the other hand, a heart-cut two-dimensional achiral-chiral liquid chromatography combining triple quadropole-linear ion trap mass spectrometry system (2D LC-MS/MS) was developed for simultaneous enantiospecific quantification of eighteen coumarins, including seven pairs of enantiomers. Eleven APs (1-11) were recruited to propose UV absorption characteristics and electrospray ionization fragmentation patterns of APs. A total of 42 components were categorized into APs based on their UV spectral properties and identified according to the proposed mass fragmentation pathways, while two linear-type furanocoumarins (12-13) were unambiguously assigned by further purification. A Capcell core RP-C18 column was employed in the primary LC dimension to achieve efficient racemic separation for the main chemical constituents (1-9 and 12-13) in Peucedani Radix, while a Chiralpak AD-RH column was utilized in the secondary dimension to contribute enantioselective separation for seven enantiomerically enriched components (1, 3 and 5-9). Collectively, the results provided the chemical evidences for revealing the material basis of the therapeutic effects of Peucedani Radix, and the developed 2D LC-MS/MS system in the present study is expected to be an ideal tool for the quality control of Peucedani Radix as well as a reliable technique for complex matrices containing both
Fermions, Skyrmions and the 3-sphere
NASA Astrophysics Data System (ADS)
Goatham, Stephen W.; Krusch, Steffen
2010-01-01
This paper investigates a background charge one Skyrme field chirally coupled to light fermions on the 3-sphere. The Dirac equation for the system commutes with a generalized angular momentum or grand spin. It can be solved explicitly for a Skyrme configuration given by the hedgehog form. The energy spectrum and degeneracies are derived for all values of the grand spin. Solutions for non-zero grand spin are each characterized by a set of four polynomials. The paper also discusses the energy of the Dirac sea using zeta-function regularization.
Coleman, W M; Lawrence, B M
2000-03-01
A viable approach for the determination of sources of essential oils based on automatic injection solid-phase microextraction-chiral-gas chromatography-mass selective detection is demonstrated. With no sample preparation, it is shown that the source of essential oils such as peppermint, spearmint, and rosemary can be easily distinguished. Short fiber exposure times of approximately 6 s to the headspace above submicroliter quantities of the selected oils are all that is required to obtain both the required sensitivity and resolution to afford analyses with excellent reproducibilities (relative standard deviation values consistently less than 5.0%).
Bragg, William; Shamsi, Shahab A.
2014-01-01
To fulfill the ever growing demand for rapid chiral analysis, this research presents an approach for highthroughput enantiomeric separations and sensitive detection of model chiral analytes using capillary electrochromatography (CEC) with UV and MS detection. This was achieved utilizing a short 7 cm CEC columns packed with cellulose tris (3,5-dimethyl-phenylcarbamate) (CDMPC) or sulfonated cellulose tris (3,5-dimethylphenylcarbamate) (CDMPC-SO3) chiral stationary phases (CSPs) applying outlet side injections in CEC-UV. The separation performance was compared between CDMPC and CDMPC-SO3 CSPs for rapid enantio-separation in CEC-UV mode. In addition, using a high sensitivity UV-flow cell in combination with outlet side injections, the S/N and hence the limit of detection of chiral drug could be improved. The 7-cm packed column was also used with traditional inlet injections for CEC coupled to a low-cost single-quadrupole MS. While outlet side injection was not possible in CEC-MS due to instrumentation constraints, the combined use of a short 7 cm column packed with CDMPC-SO3 CSP provided several fold higher throughput. Both CEC-UV and CEC-MS with short packed bed has the potential for a simple, sensitive and cost-effective method for enantiomeric drug profiling in biological samples. PMID:25264392
Unquenched determination of the kaon parameter B{sub K} from improved staggered fermions
Gamiz, Elvira; Collins, Sara; Davies, Christine T.H.; Lepage, G. Peter; Shigemitsu, Junko; Wingate, Matthew
2006-06-01
The use of improved staggered actions (HYP, Asqtad) has been proved to reduce the scaling corrections that affected previous calculations of B{sub K} with unimproved (standard) staggered fermions in the quenched approximation. This improved behavior allows us to perform a reliable calculation of B{sub K} including quark vacuum polarization effects, using the MILC configurations with n{sub f}=2+1 flavors of sea fermions. We perform such a calculation for a single lattice spacing, a=0.125 fm, and with kaons made up of degenerate quarks with m{sub s}/2. The valence strange quark mass m{sub s} is fixed to its physical value and we use two different values of the light sea quark masses. After a chiral extrapolation of the results to the physical value of the sea quark masses, we find B-circumflex{sub K}=0.83{+-}0.18, where the error is dominated by the uncertainty in the lattice to continuum matching at O({alpha}{sub s}{sup 2}). The matching will need to be improved to get the precision needed to make full use of the experimental data on {epsilon}{sub K} to constrain the unitarity triangle.
Baryon mass splittings and strong $\mathit{CP}$ violation in SU(3) chiral perturbation theory
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 up 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.
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
Fermion hierarchy from sfermion anarchy
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
Fermion hierarchy from sfermion anarchy
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 and 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.
The chirally rotated Schrödinger functional: theoretical expectations and perturbative tests
NASA Astrophysics Data System (ADS)
Brida, Mattia Dalla; Sint, Stefan; Vilaseca, Pol
2016-08-01
The chirally rotated Schrödinger functional (χSF) with massless Wilson-type fermions provides an alternative lattice regularization of the Schrödinger functional (SF), with different lattice symmetries and a common continuum limit expected from universality. The explicit breaking of flavour and parity symmetries needs to be repaired by tuning the bare fermion mass and the coefficient of a dimension 3 boundary counterterm. Once this is achieved one expects the mechanism of automatic O( a) improvement to be operational in the χSF, in contrast to the standard formulation of the SF. This is expected to significantly improve the attainable precision for step-scaling functions of some composite operators. Furthermore, the χSF offers new strategies to determine finite renormalization constants which are traditionally obtained from chiral Ward identities. In this paper we consider a complete set of fermion bilinear operators, define corresponding correlation functions and explain the relation to their standard SF counterparts. We discuss renormalization and O( a) improvement and then use this set-up to formulate the theoretical expectations which follow from universality. Expanding the correlation functions to one-loop order of perturbation theory we then perform a number of non-trivial checks. In the process we obtain the action counterterm coefficients to one-loop order and reproduce some known perturbative results for renormalization constants of fermion bilinears. By confirming the theoretical expectations, this perturbative study lends further support to the soundness of the χSF framework and prepares the ground for non-perturbative applications.
Plutonium-Based Heavy-Fermion Systems
NASA Astrophysics Data System (ADS)
Bauer, E. D.; Thompson, J. D.
2015-03-01
An effective mass of charge carriers that is significantly larger than the mass of a free electron develops at low temperatures in certain lanthanide- and actinide-based metals, including those formed with plutonium, owing to strong electron-electron interactions. This heavy-fermion mass is reflected in a substantially enhanced electronic coefficient of specific heat Î³, which for elemental Pu is much larger than that of normal metals. By our definition, there are twelve Pu-based heavy-fermion compounds, most discovered recently, whose basic properties are known and discussed. Relative to other examples, these Pu-based heavy-fermion systems are particularly complex owing in part to the possible simultaneous presence of multiple, nearly degenerate 5fn configurations. This complexity poses significant opportunities as well as challenges, including understanding the origin of unconventional superconductivity in some of these materials.
Localization and chiral symmetry in three flavor domain wall QCD
Antonio, David J.; Bowler, Kenneth C.; Boyle, Peter A.; Hart, Alistair; Kenway, Richard D.; Tweedie, Robert J.; Christ, Norman H.; Cohen, Saul D.; Li, Shu; Lin, Meifeng; Mawhinney, Robert D.; Clark, Michael A.; Dawson, Chris; Joo, Balint; Jung, Chulwoo; Maynard, Christopher M.; Ohta, Shigemi; Yamaguchi, Azusa
2008-01-01
We present results for the dependence of the residual mass of domain wall fermions on the size of the fifth dimension and its relation to the density and localization properties of low-lying eigenvectors of the corresponding Hermitian Wilson Dirac operator in three flavor domain wall QCD. Using the DBW2 and Iwasaki gauge actions, we generate ensembles of configurations with a 16{sup 3}x32 space-time volume and an extent of 8 in the fifth dimension for the sea quarks. We demonstrate the existence of a regime where the degree of locality, the size of chiral symmetry breaking, and the rate of topology change can be acceptable for inverse lattice spacings a{sup -1}{>=}1.6 GeV, enabling a programme of simulations of 2+1 flavor QCD to be conducted safely in this region of parameter space.
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.
Wang, S.-Y.; Boyanovsky, D.; Vega, H. J. de; Lee, D.-S.; Ng, Y. J.
2000-03-15
We study the transport coefficients, damping rates, and mean free paths of soft fermion collective excitations in a hot fermion-gauge-scalar plasma with the goal of understanding the main physical mechanisms that determine transport of chirality in scenarios of nonlocal electroweak baryogenesis. The focus is on identifying the different transport coefficients for the different branches of soft collective excitations of the fermion spectrum. These branches correspond to collective excitations with opposite ratios of chirality to helicity and different dispersion relations. By combining results from the hard thermal loop (HTL) resummation program with a novel mechanism of fermion damping through heavy scalar decay, we obtain a robust description of the different damping rates and mean free paths for the soft collective excitations to leading order in HTL and lowest order in the Yukawa coupling. The space-time evolution of wave packets of collective excitations unambiguously reveals the respective mean free paths. We find that whereas both the gauge and scalar contribution to the damping rates are different for the different branches, the difference of mean free paths for both branches is mainly determined by the decay of the heavy scalar into a hard fermion and a soft collective excitation. We argue that these mechanisms are robust and are therefore relevant for nonlocal scenarios of baryogenesis either in the standard model or extensions thereof. (c) 2000 The American Physical Society.
Entanglement in fermionic systems
Banuls, Mari-Carmen; Cirac, J. Ignacio; Wolf, Michael M.
2007-08-15
The anticommuting properties of fermionic operators, together with the presence of parity conservation, affect the concept of entanglement in a composite fermionic system. Hence different points of view can give rise to different reasonable definitions of separable and entangled states. Here we analyze these possibilities and the relationship between the different classes of separable states. The behavior of the various classes when taking multiple copies of a state is also studied, showing that some of the differences vanish in the asymptotic regime. In particular, in the case of only two fermionic modes all the classes become equivalent in this limit. We illustrate the differences and relations by providing a complete characterization of all the sets defined for systems of two fermionic modes. The results are applied to Gibbs states of infinite chains of fermions whose interaction corresponds to a XY Hamiltonian with transverse magnetic field.
Weyl fermions induced magnon electrodynamics in a Weyl semimetal
NASA Astrophysics Data System (ADS)
Hutasoit, Jimmy A.; Zang, Jiadong; Roiban, Radu; Liu, Chao-Xing
2014-10-01
Weyl fermions, which are fermions with definite chiralities, can give rise to anomalous breaking of the symmetry of the physical system that they are a part of. In their (3+1)-dimensional realizations in condensed matter systems, i.e., the so-called Weyl semimetals, this anomaly gives rise to topological electromagnetic response of magnetic fluctuations, which takes the form of nonlocal interaction between magnetic fluctuations and electromagnetic fields. We study the physical consequences of this nonlocal interaction, including electric field assisted magnetization dynamics, an extra gapless magnon dispersion, and polariton behaviors that feature "sibling" bands in small magnetic fields.
NASA Astrophysics Data System (ADS)
Cossu, Guido; Fukaya, Hidenori; Hashimoto, Shoji; Kaneko, Takashi; Noaki, Jun-Ichi
2016-09-01
We compute the chiral condensate in 2 + 1-flavor QCD through the spectrum of low-lying eigenmodes of the Dirac operator. The number of eigenvalues of the Dirac operator is evaluated using a stochastic method with an eigenvalue filtering technique on the background gauge configurations generated by lattice QCD simulations including the effects of dynamical up, down, and strange quarks described by the Möbius domain-wall fermion formulation. The low-lying spectrum is related to the chiral condensate, which is one of the leading-order low-energy constants in chiral effective theory, as dictated by the Banks-Casher relation. The spectrum shape and its dependence on the sea quark masses calculated in numerical simulations are consistent with the expectation from one-loop chiral perturbation theory. After taking the chiral limit as well as the continuum limit using the data at three lattice spacings in the range 0.080-0.045 fm, we obtain Σ(2 GeV) = 270.0(4.9) MeV, with the error combining those from statistical and various sources of systematic error. The finite volume effect is confirmed to be under control by a direct comparison of the results from two different volumes at the lightest available sea quarks corresponding to 230 MeV pions.
STOUT SMEARING FOR TWISTED FERMIONS.
SCHOLZ,W.; JANSEN, K.; McNEILE, C.; MONTVAY, I.; RICHARDS, C.; URBACH, C.; WENGER, U.
2007-07-30
The effect of Stout smearing is investigated in numerical simulations with twisted mass Wilson quarks. The phase transition near zero quark mass is studied on 12{sup 3} x 24, 16{sup 3} x 32 and 24{sup 3} x 48 lattices at lattice spacings a {approx_equal} 0.1-0.125 fm. The phase structure of Wilson fermions with twisted mass ({mu}) has been investigated in [1,2]. As it is explained there, the observed first order phase transition limits the minimal pion mass which can be reached in simulations at a given lattice spacing: m{sub k}{sup min} {approx_equal} {theta}(a). The phase structure is schematically depicted in the left panel of Fig. I . The phase transition can be observed in simulations with twisted mass fermions, for instance, as a ''jump'' or even metastabilities in the average plaquette value as a function of the hopping parameter ({kappa}). One possibility to weaken the phase transition and therefore allow for lighter pion masses at a given lattice spacing is to use an improved gauge action like the DBW2, Iwasaki, or tree-level Symanzik (tlSym) improved gauge action instead of the simple Wilson gauge action. This has been successfully demonstrated in [3,4,5]. Here we report on our attempts to use a smeared gauge field in the fermion lattice Dirac operator to further reduce the strength of the phase transition. This is relevant in simulations with N{sub f} = 2 + 1 + 1 (u,d,s,c) quark flavors [6] where the first order phase transition becomes stronger compared to N{sub f} = 2 simulations. The main impact of the above mentioned improved gauge actions on the gauge fields occurring in simulations is to suppress short range fluctuations (''dislocations'') and the associated ''exceptionally small'' eigenvalues of the fermion matrix. The same effect is expected from smearing the gauge field links in the fermion action. The cumulated effect of the improved gauge action and smeared links should allow for a smaller pion mass at a given lattice spacing and volume. Our
Nonperturbative Renormalization of Composite Operators with Overlap Fermions
J.B. Zhang; N. Mathur; S.J. Dong; T. Draper; I. Horvath; F. X. Lee; D.B. Leinweber; K.F. Liu; A.G. Williams
2005-12-01
We compute non-perturbatively the renormalization constants of composite operators on a quenched 16{sup 3} x 28 lattice with lattice spacing a = 0.20 fm for the overlap fermion by using the regularization independent (RI) scheme. The quenched gauge configurations were generated with the Iwasaki action. We test the relations Z{sub A} = Z{sub V} and Z{sub S} = Z{sub P} and find that they agree well (less than 1%) above {mu} = 1.6 GeV. We also perform a Renormalization Group (RG) analysis at the next-to-next-to-leading order and match the renormalization constants to the {ovr MS} scheme. The wave-function renormalization Z{sub {psi}} is determined from the vertex function of the axial current and Z{sub A} from the chiral Ward identity. Finally, we examine the finite quark mass behavior for the renormalization factors of the quark bilinear operators. We find that the (pa){sup 2} errors of the vertex functions are small and the quark mass dependence of the renormalization factors to be quite weak.
Effective pion mass term and the trace anomaly
NASA Astrophysics Data System (ADS)
Golterman, Maarten; Shamir, Yigal
2017-01-01
Recently, we developed an effective theory of pions and a light dilatonic meson for gauge theories with spontaneously broken chiral symmetry that are close to the conformal window. The pion mass term in this effective theory depends on an exponent y . We derive the transformation properties under dilatations of the renormalized fermion mass and use this to rederive y =3 -γm* , where γm* is the fixed-point value of the mass anomalous dimension at the sill of the conformal window. This value for y is consistent with the trace anomaly of the underlying near-conformal gauge theory.
Wilson Fermions and Axion Electrodynamics in Optical Lattices
Bermudez, A.; Martin-Delgado, M. A.; Mazza, L.; Rizzi, M.; Goldman, N.; Lewenstein, M.
2010-11-05
We show that ultracold Fermi gases in optical superlattices can be used as quantum simulators of relativistic lattice fermions in 3+1 dimensions. By exploiting laser-assisted tunneling, we find an analogue of the so-called naive Dirac fermions, and thus provide a realization of the fermion doubling problem. Moreover, we show how to implement Wilson fermions, and discuss how their mass can be inverted by tuning the laser intensities. In this regime, our atomic gas corresponds to a phase of matter where Maxwell electrodynamics is replaced by axion electrodynamics: a 3D topological insulator.
Wilson fermions and axion electrodynamics in optical lattices.
Bermudez, A; Mazza, L; Rizzi, M; Goldman, N; Lewenstein, M; Martin-Delgado, M A
2010-11-05
We show that ultracold Fermi gases in optical superlattices can be used as quantum simulators of relativistic lattice fermions in 3+1 dimensions. By exploiting laser-assisted tunneling, we find an analogue of the so-called naive Dirac fermions, and thus provide a realization of the fermion doubling problem. Moreover, we show how to implement Wilson fermions, and discuss how their mass can be inverted by tuning the laser intensities. In this regime, our atomic gas corresponds to a phase of matter where Maxwell electrodynamics is replaced by axion electrodynamics: a 3D topological insulator.
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.
Drag suppression in anomalous chiral media
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 a super fluid. Finally, we demonstrate and confirm our general results with two complementary examples: weakly coupled chiral fermion gases and strongly interacting chiral liquids.
Drag suppression in anomalous chiral media
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
Drag suppression in anomalous chiral media
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 a super fluid. Finally, we demonstrate and confirm our general results with two complementary examples: weakly coupled chiral fermion gases and strongly interacting chiral liquids.
Two-flavor lattice QCD in the {epsilon} regime and chiral random matrix theory
Fukaya, H.; Aoki, S.; Chiu, T. W.; Ogawa, K.; Hashimoto, S.; Kaneko, T.; Yamada, N.; Matsufuru, H.; Noaki, J.; Onogi, T.
2007-09-01
The low-lying eigenvalue spectrum of the QCD Dirac operator in the {epsilon} regime is expected to match with that of chiral random matrix theory (ChRMT). We study this correspondence for the case including sea quarks by performing two-flavor QCD simulations on the lattice. Using the overlap fermion formulation, which preserves exact chiral symmetry at finite lattice spacings, we push the sea quark mass down to {approx}3 MeV on a 16{sup 3}x32 lattice at a lattice spacing a{approx_equal}0.11 fm. We compare the low-lying eigenvalue distributions and find a good agreement with the analytical predictions of ChRMT. By matching the lowest-lying eigenvalue we extract the chiral condensate, {sigma}{sup MS}(2 GeV)=(251{+-}7{+-}11 MeV){sup 3}, where errors represent statistical and higher order effects in the {epsilon} expansion. We also calculate the eigenvalue distributions on the lattices with heavier sea quarks at two lattice spacings. Although the {epsilon} expansion is not applied for those sea quarks, we find a reasonable agreement of the Dirac operator spectrum with ChRMT. The value of {sigma}, after extrapolating to the chiral limit, is consistent with the estimate in the {epsilon} regime.
Moldovan, Radu-Cristian; Bodoki, Ede; Kacsó, Timea; Servais, Anne-Catherine; Crommen, Jacques; Oprean, Radu; Fillet, Marianne
2016-10-07
In the context of bioanalytical method development, process automatization is nowadays a necessity in order to save time, improve method reliability and reduce costs. For the first time, a fully automatized micellar electrokinetic chromatography-mass spectrometry (MEKC-MS) method with in-capillary derivatization was developed for the chiral analysis of d- and l-amino acids using (-)-1-(9-fluorenyl) ethyl chloroformate (FLEC) as labeling reagent. The derivatization procedure was optimized using an experimental design approach leading to the following conditions: sample and FLEC plugs in a 2:1 ratio (15s, 30mbar: 7.5s, 30mbar) followed by 15min of mixing using a voltage of 0.1kV. The formed diastereomers were then separated using a background electrolyte (BGE) consisting of 150mM ammonium perfluorooctanoate (APFO) (pH=9.5) and detected by mass spectrometry (MS). Complete chiral resolution was obtained for 8 amino acids, while partial separation was achieved for 6 other amino acid pairs. The method showed good reproducibility and linearity in the low micromolar concentration range. The applicability of the method to biological samples was tested by analyzing artificial cerebrospinal fluid (aCSF) samples. Copyright © 2016 Elsevier B.V. All rights reserved.
Yang, Jing; Carmella, Steven G; Hecht, Stephen S
2017-02-15
We have developed a chiral stationary phase liquid chromatography-nanoelectrospray ionization-high resolution tandem mass spectrometry (LC-NSI-HRMS/MS) method to investigate the enantiomeric composition of low parts per trillion amounts of the carcinogen N'-nitrosonornicotine (NNN) in the urine of cigarette smokers and smokeless tobacco users. (S)-NNN is the major enantiomer in tobacco and is more carcinogenic than (R)-NNN in rats, but no data are available on the enantiomeric composition of NNN in humans. The method used [(13)C6]NNN as an internal standard and [pyridine-D4]nornicotine to monitor possible artifactual formation of NNN, which was found to be less than 2% of the quantified NNN. The enantiomeric composition of NNN (20.5±27.1fmol/mL urine) in 20 cigarette smokers was 67±5% (S)-NNN while that in 10 smokeless tobacco users (67.1±56.7 fmol/mL urine) was 56±3% (S)-NNN. These results demonstrate that the highly carcinogenic (S)-NNN is the major enantiomer in human urine, and that the enantiomeric composition of NNN in human urine is remarkably similar to that in cigarette smoke and smokeless tobacco. This is the first study to combine chiral stationary phase separations with nanoelectrospray ionization and high resolution tandem mass spectrometry to quantify trace levels of enantiomeric metabolites in human urine.
Dynamical mass generation in QED 3 beyond the instantaneous approximation
NASA Astrophysics Data System (ADS)
Xiao, Hai-Xiao; Li, Jian-Feng; Wei, Wei; Yin, Pei-Lin; Zong, Hong-Shi
2017-07-01
In this paper, we investigate dynamical mass generation in (2+1)-dimensional quantum electrodynamics at finite temperature. Many studies are carried out within the instantaneous-exchange approximation, which ignores all but the zero-frequency component of the boson propagator and fermion self-energy function. We extend these studies by taking the retardation effects into consideration. In this paper, we get the explicit frequency n and momentum p dependence of the fermion self-energy function and identify the critical temperature for different fermion flavors in the chiral limit. Also, the phase diagram for spontaneous symmetry breaking in the theory is presented in T c-N f space. The results show that the chiral condensate is just one-tenth of the scale of previous results, and the chiral symmetry is restored at a smaller critical temperature. Supported by National Natural Science Foundation of China (11475085, 11535005, 11690030), Natural Science Foundation of Jiangsu Province (BK20130387) and Jiangsu Planned Projects for Postdoctoral Research Funds (1501035B)
Check for Chirality in Nuclear Physics
Tonev, D.; De Angelis, G.; Gadea, A.; Marginean, N.; Napoli, D. R.; Petkov, P.; Dewald, A.; Pejovic, P.; Fitzler, A.; Moeller, O.; Zell, K. O.; Brant, S.; Frauendorf, S.; Zhong, Q.; Balabanski, D.; Bazzacco, D.; Lenzi, S.; Lunardi, S.; Zhang Jingye; Zhang, Y. H.
2006-04-26
Exited states in 134Pr were populated in the fusion-evaporation reaction 119Sn(19F, 4n)134Pr. Recoil distance Doppler-shift and Doppler-shift attenuation measurements using the Euroball spectrometer, in conjunction with the inner BGO ball and the Cologne plunger, were performed at beam energies of 87 MeV and 83 MeV, respectively. Reduced transition probabilities in 134Pr are compared to the predictions of the two quasiparticle+triaxial rotor and interacting boson fermion-fermion models. Both experimental results and theoretical calculations support only within a dynamical context the presence of intrinsic chirality in 134Pr.
Global anomalies in Chiral Lattice Gauge Theory
NASA Astrophysics Data System (ADS)
Bär, Oliver; Campos, Isabel
As first realized by Witten an SU(2) gauge theory coupled to a single Weyl fermion suffers from a global anomaly. This problem is addressed here in the context of the recent developments on chiral gauge theories on the lattice. We find Witten's anomaly manifests in the impossibility of defining globally a fermion measure that reproduces the proper continuum limit. Moreover, following Witten's original argument, we check numerically the crossing of the lowest eigenvalues of Neuberger's operator along a path connecting two gauge fields that differ by a topologically non-trivial gauge transformation.
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
Mizuno, Hajime; Miyazaki, Yasuto; Ito, Keisuke; Todoroki, Kenichiro; Min, Jun Zhe; Toyo'oka, Toshimasa
2016-10-07
A method for the determination of D-Aspartic acid (D-Asp) and its D/L ratio in peptides and proteins has been developed. This method was carried out with good separation of the D/L chiral peptide pairs by combination of a chiral derivatization and an ADME column separation. Furthermore, a cationic derivatization reagent, DBD-Py-NCS, increased the sensitivity of the ESI-MS/MS detection. To confirm the comprehensive peptide analysis, synthesized α-Crystallin tryptic peptides, which included D-Asp residues, were analyzed. The 5 pairs of D/L-Asp that included peptide diastereomers were well separated. Their peak resolutions were more than 1.5 and the results were reproducible (RSD<0.05, n=5). As an application of this method, we analyzed the α-Crystallin standard and UV irradiated α-Crystallin. After trypsin digestion and DBD-Py-NCS derivatization, the tryptic peptide derivatives were applied to LC-MS/MS. Based on the results of peptide sequence identification, almost all the tryptic peptides of the αA- and αB-Crystallin homologous subunits of α-Crystallin were detected as DBD-Py NCS derivatives. However, there was no D-Asp residue in the standard proteins. In the case of the UV irradiated α-Crystallin, Asp(76) and Asp(84) in the αA-Crystallin and Asp(96) in αB-Crystallin were racemized to D-Asp. These results show that this proposed chiral peptide LC-MS/MS method using chiral derivatization provides a rapid and sensitive analysis for post translational Asp racemization sites in aging proteins.
Chiral anomaly in Dirac semimetals due to dislocations
NASA Astrophysics Data System (ADS)
Chernodub, M. N.; Zubkov, M. A.
2017-03-01
The dislocation in Dirac semimetal carries an emergent magnetic flux parallel to the dislocation axis. We show that due to the emergent magnetic field, the dislocation accommodates a single fermion massless mode of the corresponding low-energy one-particle Hamiltonian. The mode is propagating along the dislocation with its spin directed parallel to the dislocation axis. In agreement with the chiral anomaly observed in Dirac semimetals, an external electric field results in the spectral flow of the one-particle Hamiltonian, in pumping of the fermionic quasiparticles out from vacuum, and in creating a nonzero axial (chiral) charge in the vicinity of the dislocation.
Chiral symmetry breaking with lattice propagators
Aguilar, A. C.; Papavassiliou, J.
2011-01-01
We study chiral symmetry breaking using the standard gap equation, supplemented with the infrared-finite gluon propagator and ghost dressing function obtained from large-volume lattice simulations. One of the most important ingredients of this analysis is the non-Abelian quark-gluon vertex, which controls the way the ghost sector enters into the gap equation. Specifically, this vertex introduces a numerically crucial dependence on the ghost dressing function and the quark-ghost scattering amplitude. This latter quantity satisfies its own, previously unexplored, dynamical equation, which may be decomposed into individual integral equations for its various form factors. In particular, the scalar form factor is obtained from an approximate version of the 'one-loop dressed' integral equation, and its numerical impact turns out to be rather considerable. The detailed numerical analysis of the resulting gap equation reveals that the constituent quark mass obtained is about 300 MeV, while fermions in the adjoint representation acquire a mass in the range of (750-962) MeV.
Phase of the fermion determinant at nonzero chemical potential.
Splittorff, K; Verbaarschot, J J M
2007-01-19
We show that in the microscopic domain of QCD (also known as the domain) at nonzero chemical potential the average phase factor of the fermion determinant is nonzero for micro
Chiral solution to the Ginsparg-Wilson equation
NASA Astrophysics Data System (ADS)
Grabowska, Dorota M.; Kaplan, David B.
2016-12-01
We present a chiral solution of the Ginsparg-Wilson equation. This work is motivated by our recent proposal for nonperturbatively regulating chiral gauge theories, where five-dimensional domain wall fermions couple to a four-dimensional gauge field that is extended into the extra dimension as the solution to a gradient flow equation. Mirror fermions at the far surface decouple from the gauge field as if they have form factors that become infinitely soft as the distance between the two surfaces is increased. In the limit of an infinite extra dimension we derive an effective four-dimensional chiral overlap operator which is shown to obey the Ginsparg-Wilson equation, and which correctly reproduces a number of properties expected of chiral gauge theories in the continuum.
Iliesiu, Luca; Kos, Filip; Poland, David; ...
2016-03-17
We study the conformal bootstrap for a 4-point function of fermions <ψψψψ> 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 CT. 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.
Iliesiu, Luca; Kos, Filip; Poland, David; Pufu, Silviu S.; Simmons-Duffin, David; Yacoby, Ran
2016-03-17
We study the conformal bootstrap for a 4-point function of fermions <ψψψψ> 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.
Li, Yuanbo; Dong, Fengshou; Liu, Xingang; Xu, Jun; Chen, Xiu; Han, Yongtao; Liang, Xuyang; Zheng, Yongquan
2013-04-15
A novel and sensitive chiral liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous measuring individual enantiomers of 9 pesticides including herbicides, insecticides, and fungicides in soil and water. The separation and determination were performed using reversed-phase chromatography on an amylose chiral stationary phase, a Chiralpak AD-RH column, under gradient elution using a mixture of ACN-2mM ammonium acetate in water as the mobile phase at 0.45 mL/min flow rate. The effects of three cellulose-based columns and three amylose-based columns on the separation were also investigated. The QuEChERS (acronym for Quick, Easy, Cheap, Effective, Rugged and Safe) method and solid-phase extraction (SPE) were used for the extraction and clean-up of the soil and water samples, respectively. Parameters including the matrix effect, linearity, precision, accuracy and stability were undertaken. Under optimal conditions, the mean recoveries for all enantiomers from the soil and water samples were ranged from 77.8% to 106.2% with the relative standard deviations (RSD) less than 14.2%. Good linearity (at least R(2) ≥ 0.9986) was obtained for all studied analytes in the soil and water matrix calibration curves over the range from 2.0 to 125 μg/L. The limits of detection (LOD) for all enantiomers in the soil and water were less than 1.8 μg/kg or μg/L, whereas the limit of quantification (LOQ) did not exceed 5.0 μg/kg or μg/L. The results of the method validation confirm that this proposed method is convenient and reliable for the enantioselective determination of the enantiomers of 9 chiral pesticides in soil and water. Copyright © 2013 Elsevier B.V. All rights reserved.
Li, Jing; Zhang, Yuting; Cheng, Youpu; Yuan, Shankui; Liu, Lei; Shao, Hui; Li, Hui; Li, Na; Zhao, Pengyue; Guo, Yongze
2016-03-20
A novel and sensitive ultra-high performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous enantioselective determination of flufiprole and its hydrolysis metabolite in paddy field ecosystem. The separation and determination were performed using reversed-phase chromatography on a novel cellulose chiral stationary phase, a Lux Cellulose-4 (150 mm × 2.0 mm) column, under isocratic conditions at 0.25 mL/min flow rate. The effects of other four different polysaccharide-based chiral stationary phases (CSPs) on the separation and simultaneous enantioseparation of the two target compounds were also evaluated. The elution orders of the eluting enantiomers were identified by an optical rotation detector. Modified QuEChERS (acronym for Quick, Easy, Cheap, Effective, Rugged and Safe) method and solid-phase extraction (SPE) were used for the enrichment and cleanup of paddy water, rice straw, brown rice and paddy soil samples, respectively. Parameters including the matrix effect, linearity, precision, accuracy and stability were evaluated. Under the optimal conditions, the mean recoveries for all enantiomers from the above four sample matrix were ranged from 83.6% to 107%, with relative standard deviations (RSD) in the range of 1.0-5.8%. Coefficients of determination R(2)≥0.998 were achieved for each enantiomer in paddy water, rice straw, brown rice and paddy soil matrix calibration curves within the range of 5-500 μg/kg. The limits of quantification (LOQ) for all stereoisomers in the above four matrices were all below 2.0 μg/kg. The methodology was successfully applied for simultaneously enantioselective analysis of flufiprole enantiomers and their chiral metabolite in the real samples, indicating its efficacy in investigating the environmental stereochemistry of flufiprole in paddy field ecosystem.
BK using HYP-smeared staggered fermions in Nf = 2 + 1 unquenched QCD
Jung, C.; Bae, T.; Jang, Y-C.; Kim, H-J.; Kim, J.; Kim, K; Lee, W.; Sharpe, S.; Yoon, B.
2010-12-20
We present results for the kaon mixing parameter B{sub K} calculated using HYP (hypercubic fat link)-smeared improved staggered fermions on the asqtad lattices generated by the MILC collaboration. We use three lattice spacings (a{approx} 0.12, 0.09 and 0.06 fm), ten different valence-quark masses (m {approx} m{sub s}/10-m{sub s}), and several light sea-quark masses in order to control the continuum and chiral extrapolations. We derive the next-to-leading order staggered chiral perturbation theory (SChPT) results necessary to fit our data, and use these results to do extrapolations based both on SU(2) and SU(3) SChPT. The SU(2) fitting is particularly straightforward because parameters related to taste breaking and matching errors appear only at next-to-next-to-leading order. We match to the continuum renormalization scheme [naive dimensional regularization (NDR)] using one-loop perturbation theory. Our final result is from the SU(2) analysis, with the SU(3) result providing a (less accurate) cross check. We find B{sub K}(NDR, {mu} = 2 GeV) = 0.529 {+-} 0.009 {+-} 0.032 and B{sub K} = B{sub K}(RGI) = 0.724 {+-} 0.012 {+-} 0.043, where the first error is statistical and the second systematic. The error is dominated by the truncation error in the matching factor. Our results are consistent with those obtained using valence domain-wall fermions on lattices generated with asqtad or domain-wall sea quarks.
A possible connection between massive fermions and dark energy
Goldman, Terrance; Stephenson, G J; Alsing, P M; Mckellar, B H J
2009-01-01
In a dense cloud of massive fermions interacting by exchange of a light scalar field, the effective mass of the fermion can become negligibly small. As the cloud expands, the effective mass and the total energy density eventually increase with decreasing density. In this regime, the pressure-density relation can approximate that required for dark energy. They apply this phenomenon to the expansion of the Universe with a very light scalar field and infer relations between the parameters available and cosmological observations. Majorana neutrinos at a mass that may have been recently determined, and fermions such as the Lightest Supersymmetric Particle (LSP) may both be consistent with current observations of dark energy.
Anisovich, A. V.; Burkert, Volker D.; Hartmann, J.; Klempt, E.; Nikonov, V. A.; Pasyuk, E.; Sarantsev, A. V.; Strauch, S.; Thoma, U.
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^{0}p 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, and that these two resonances should be degenerate in mass. Lastly, our findings are in conflict with this prediction.
Some remarks on the Ginsparg-Wilson fermion
NASA Astrophysics Data System (ADS)
Chiu, Ting-Wai
2000-11-01
We note that Fujikawa's proposal of generalization of the Ginsparg-Wilson relation is equivalent to setting R=(aγ 5D) 2k in the original Ginsparg-Wilson relation Dγ 5+γ 5D=2aDRγ 5D . An explicit realization of D follows from the Overlap construction. The general properties of D are derived. The chiral properties of these higher-order ( k>0 ) realizations of Overlap Dirac operator are compared to those of the Neuberger-Dirac operator ( k=0 ), in terms of the fermion propagator, the axial anomaly and the fermion determinant in a background gauge field. Our present results (up to lattice size 16×16 ) indicate that the chiral properties of the Neuberger-Dirac operator are better than those of higher-order ones.
Magnetotransport in Dirac metals: Chiral magnetic effect and quantum oscillations
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 Cd3As2.
Magnetotransport in Dirac metals: Chiral magnetic effect and quantum oscillations
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_{3}As_{2}.
Chiral kinetic theory and anomalous hydrodynamics in even spacetime dimensions
NASA Astrophysics Data System (ADS)
Dwivedi, Vatsal; Stone, Michael
2017-04-01
We apply chiral kinetic theory to a gas of weakly interacting Weyl fermions coupled to electromagnetism in (2N + 1) + 1 spacetime dimensions to obtain the ‘Gibbs free energy current’ from which all equilibrium finite temperature anomalous contributions, such as the chiral magnetic and vortical currents, can be derived. Our results agree with those derived previously using thermodynamic constraints.
Generalized Bloch theorem and chiral transport phenomena
NASA Astrophysics Data System (ADS)
Yamamoto, Naoki
2015-10-01
Bloch theorem states the impossibility of persistent electric currents in the ground state of nonrelativistic fermion systems. We extend this theorem to generic systems based on the gauged particle number symmetry and study its consequences on the example of chiral transport phenomena. We show that the chiral magnetic effect can be understood as a generalization of the Bloch theorem to a nonequilibrium steady state, similarly to the integer quantum Hall effect. On the other hand, persistent axial currents are not prohibited by the Bloch theorem and they can be regarded as Pauli paramagnetism of relativistic matter. An application of the generalized Bloch theorem to quantum time crystals is also discussed.
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.
Chiral vortical effect for bosons
NASA Astrophysics Data System (ADS)
Avkhadiev, Artur; Sadofyev, Andrey V.
2017-08-01
The thermal contribution to the chiral vortical effect is believed to be related to the axial anomaly in external gravitational fields. We use the universality of the spin-gravity interaction to extend this idea to a wider set of phenomena. We consider the Kubo formula at weak coupling for the spin current of a vector field and derive a novel anomalous effect caused by the medium rotation: the chiral vortical effect for bosons. The effect consists in a spin current of vector bosons along the angular velocity of the medium. We argue that it has the same anomalous nature as in the fermionic case and show that this effect provides a mechanism for helicity transfer, from flow helicity to magnetic helicity.
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
Hentschel, Mario; Schäferling, Martin; Duan, Xiaoyang; Giessen, Harald; Liu, Na
2017-05-01
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.
Floss, H.G.
1994-12-01
This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.
NASA Astrophysics Data System (ADS)
Hu, Wenjun; Gong, Shoushu; Sheng, Donna; Donna Sheng Team
We investigate the Heisenberg model with chiral coupling on the triangular lattice by using Gutzwiller projected fermionic states and the variational Monte Carlo technique. As the chiral coupling grows, a gapped spin liquid with non-trivial magnetic fluxes and nonzero chiral order is stabilized. Furthermore, we calculate the topological Chern number and the degeneracy of the ground state, both of which lead us to identify this flux state as the chiral spin liquid with C = 1 / 2 fractionalized Chern number. Finally, we add spatial anisotropy in the model to study the effects for the chiral order.
Jiang, Hongliang; Li, Yinghe; Pelzer, Mary; Cannon, Michelle J; Randlett, Christopher; Junga, Heiko; Jiang, Xiangyu; Ji, Qin C
2008-05-30
A sensitive and selective bioanalytical assay was developed and validated for the determination of enantiomeric molindone in human plasma using high-performance liquid chromatography-tandem mass spectrometry along with supported liquid extraction procedures. The chiral separation was evaluated and optimized on macrocyclic antibiotic type chiral stationary phases (CSPs) based on teicoplanin aglycone (Chirobiotic TAG) in polar organic, polar ionic, and reversed-phase mode chromatography, respectively. Complete baseline separation was achieved on a Chirobiotic TAG column under isocratic condition in reversed-phase chromatography. The method validation was conducted using a Chirobiotic TAG column (100 mm x 2.1 mm) over the curve range 0.100-100 ng/ml for each molindone enantiomer using 0.0500 ml of plasma sample. The flow rate was 0.8 ml/min and the total run time was 9 min. Supported liquid extraction in a 96-well plate format was used for sample preparation. Parameters including recovery, matrix effect, linearity, sensitivity, specificity, carryover, precision, accuracy, dilution integrity, and stability were evaluated. The intra- and inter-day precision and accuracy of the quality control samples at low, medium, and high concentration levels were RSD
Wang, Lin; Chai, Yunfeng; Ni, Zhangqin; Wang, Lu; Hu, Ruilin; Pan, Yuanjiang; Sun, Cuirong
2014-01-27
A tandem mass spectrometry method for high-sensitivity qualitative and quantitative discrimination of chiral amino compounds is conducted. The method is based on a chemical derivation process that uses a simple reagent, L-1-(phenylsulfonyl)pyrrolidine-carbonyl chloride, as the probe. The method is applicable in both organic solutions and biological conditions. Twenty-one pairs of enantiomer containing amino acids, amino alcohols, and amines are used to produce diastereomers using the probe via in situ reaction for 20 s at room temperature. The resulting diastereomers are successfully recognized based on the relative peak intensities of their fragments in positive mode, with the chiral recognition ability values ranging from 0.35 to 3.83. The L/D ratio of Pro spiked at different concentrations (enantiomeric excess) in both acetonitrile and dog plasma is determined by establishing calibration curves. This method achieves a lower limit of quantification of 50 pmol in analyzing amino acids using an extract ion chromatograph. The relative standard deviation for both qualitative and quantitative results is <5%. Thus, the present method is demonstrated as a new and practical technique of rapidly and sensitively determining enantiomers of amino compounds. Copyright © 2013 Elsevier B.V. All rights reserved.
Canonical gravity with fermions
Bojowald, Martin; Das, Rupam
2008-09-15
Canonical gravity in real Ashtekar-Barbero variables is generalized to allow for fermionic matter. The resulting torsion changes several expressions in Holst's original vacuum analysis, which are summarized here. This in turn requires adaptations to the known loop quantization of gravity coupled to fermions, which is discussed on the basis of the classical analysis. As a result, parity invariance is not manifestly realized in loop quantum gravity.
Zheng, Jie; Bragg, William; Hou, Jingguo; Lin, Na; Chandrasekaran, Sekar; Shamsi, Shahab A.
2009-01-01
The applications of polysaccharide phenyl carbamate derivatives as chiral stationary phases (CSPs) for capillary electrochromatography (CEC) are often hindered by longer retention times, especially using a normal-phase (NP) eluent due to very low electroosmotic flow (EOF). Therefore, in this study, we propose an approach for the aforementioned problems by introducing two new types of negatively charged sulfate and sulfonated groups for polysaccharide CSPs. These CSPs were utilized to pack CEC columns for enantioseparation with a NP eluent. Compared to conventional cellulose tris(3,5-dimethylphenyl carbamate) or CDMPC CSPs, the sulfated CDMPC CSP (sulfur content 4.25%, w/w) shortened the analysis time up to 50% but with a significant loss of enantiomeric resolution (~60%). On the other hand, the sulfonated CDMPC CSP (sulfur content 1.76%, w/w) not only provided fast throughput but also maintained excellent resolving power. In addition, its synthesis is much more straightforward than the sulfated one. Furthermore, we studied several stationary phase parameters (CSP loading and silica gel pore size) and mobile phase parameters (including type of mobile phase and its composition) to evaluate the throughput and enantioselectivity. Using the optimized conditions, a chiral pool containing 66 analytes was screened to evaluate the enantioselectivity under three different mobile phase modes (i.e., NP, polar organic phase (POP) and reversed-phase (RP) eluents). Among these mobile phase modes, the RP mode showed the highest success rate, whereas some degree of complementary enantioselectivity was observed with NP and POP. Finally, the feasibility of applying this CSP for CEC–MS enantioseparation using internal tapered column was evaluated with NP, POP and RP eluents. In particular, the NP-CEC–MS provided significantly enhanced sensitivity when methanol was replaced with isopropanol in the sheath liquid. Using aminog-lutethimide as model chiral analyte, all three modes of
Chiral 2D "strange metals" from SYM
NASA Astrophysics Data System (ADS)
Berkooz, Micha; Narayan, Prithvi; Zait, Amir
2015-01-01
Familiar field theories may contain closed subsectors made out of only fermions, which can be used to explore new and unusual phases of matter in lower dimensions. We focus on the fermionic su(1, 1) sector in SYM and on its ground states, which are Fermi surface states/operators. By computing their spectrum to order ( g {YM/2} N)2, we argue that fluctuations around this Fermi surface, within the sector and in the limit k F → ∞, are governed by a chiral 1+1 dimensional sector of the "strange metal" coset SU( N ) N ⊗ SU( N ) N /SU( N )2 N . On the gravity side, the conjectured dual configuration is an S = 0 degeneration of a rotating black hole. On general grounds we expect that the near horizon excitations of ( S = 0, Ω = 1, J → ∞) degenerations of black holes will be governed by a chiral sector of a 1+1 CFT.
Hädener, Marianne; Bruni, Pia S; Weinmann, Wolfgang; Frübis, Matthias; König, Stefan
2017-02-01
Amphetamine (AM) is a powerful psychostimulant existing in two enantiomeric forms. Stereoselective analysis of AM in biosamples can assist clinicians and forensic experts in differentiating between abuse of illicitly synthesized racemic AM and ingestion of pharmaceutical AM formulations containing either S-AM or different proportions of the S- and R-enantiomers. Therefore, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying AM enantiomers in urine was newly developed. The method comprised dilution with water, followed by injection of the diluted sample onto an achiral C18 trapping column for purification and subsequent backflush elution to a chiral Lux 3 μm AMP LC column by means of a switching valve. An isocratic mobile phase of 25 % acetonitrile in 0.1 M aqueous ammonia was used for enantiomeric separation. Injection, cleanup, and backflush of the next sample were performed before the previous sample had eluted from the analytical column, thus enabling simultaneous enantioseparation of up to three samples within the analytical column. This novel chromatographic concept allowed for increased sample throughput by accelerating both the sample preparation and the LC analysis. Analyte detection was accomplished by electrospray ionization in positive ion mode and selected reaction monitoring using a triple-stage quadrupole mass spectrometer. The method was successfully validated through assessment of its linearity, lower limit of quantification, accuracy and precision, selectivity, matrix effect, carry-over, dilution integrity, and re-injection reproducibility. Linearity ranged from 0.05 to 25 mg/L for both enantiomers. Proof of the method included analysis of urine samples obtained from drug abusers and patients receiving an S-AM prodrug. Graphical Abstract Enantioselective determination of amphetamine in human urine using liquid chromatography with achiral-chiral column-switching and tandem mass spectrometry.
Mikuma, Toshiyasu; Iwata, Yuko T; Miyaguchi, Hajime; Kuwayama, Kenji; Tsujikawa, Kenji; Kanamori, Tatsuyuki; Inoue, Hiroyuki
2015-04-01
Chiral capillary electrophoresis/tandem mass spectrometry (CE/MS/MS) using a chemically modified capillary containing sulfonated groups was developed for the following 8 amphetamine-type stimulants (ATS): amphetamine, methamphetamine (MA), norephedrine, norpseudoephedrine, ephedrine (EP), pseudoephedrine (pEP), dimethylamphetamine and methylephedrine. The running buffer was 10 mM formic acid containing 20 mM highly sulfated γ-cyclodextrin (pH 2.5) as the chiral selector. All 16 enantiomers were well resolved within 60 min, and precisely identified due to their characteristic mass spectra. Further, the RSDs of the migration times of the analytes were no more than 0.3% without any standardization. (1R,2S)-(-)-EP and (1S,2S)-(+)-pEP, which are important ATS impurities originating in the precursors, were added to a highly concentrated MA solution (1 mg/mL) and analyzed as mock samples for MA impurity analysis. Acceptable repeatability of the migration times of (-)-EP and (+)-pEP (ca. 0.3% RSDs) was still observed without interference from the large amount of MA. The limits of detection (LOD) of (-)-EP and (+)-pEP were approximately 2 μg/mL, therefore, their LOD as the impurity concentrations were calculated at about 0.2%. Seized MA samples were dissolved in water at a high concentration (1 mg/mL) and analyzed by this method. (-)-EP and (+)-pEP were clearly detected as impurities. Although these compounds had similar migration times and mass spectral patterns, the fine repeatability allowed easy identification of the impurities by a simple comparison of the absolute migration times of the specimens and those of authentic standards. This study is the first to report the use of a chemically modified capillary for the impurity profiling on CE/MS/MS. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Cosmology of fermionic dark matter
Boeckel, Tillmann; Schaffner-Bielich, Juergen
2007-11-15
We explore a model for a fermionic dark matter particle family which decouples from the rest of the particles when at least all standard model particles are in equilibrium. We calculate the allowed ranges for mass and chemical potential to be compatible with big bang nucleosynthesis (BBN) calculations and WMAP data for a flat universe with dark energy ({omega}{sub {lambda}}{sup 0}=0.72, {omega}{sub M}{sup 0}=0.27, h=0.7). Futhermore we estimate the free streaming length for fermions and antifermions to allow comparison to large scale structure data (LSS). We find that for dark matter decoupling when all standard model particles are present even the least restrictive combined BBN calculation and WMAP results allow us to constrain the initial dark matter chemical potential to a highest value of 6.3 times the dark matter temperature. In this case, the resulting mass range is at most 1.8 eV{<=}m{<=}53 eV, where the upper bound scales linearly with g{sub eff}{sup s}(T{sub Dec}). From LSS we find that, similar to ordinary warm dark matter models, the particle mass has to be larger than {approx}500 eV [meaning g{sub eff}{sup s}(T{sub Dec})>10{sup 3}] to be compatible with observations of the Ly {alpha} forest at high redshift, but still the dark matter chemical potential over temperature ratio can exceed unity.
Triplet fermions and Dirac fermions in borophene
NASA Astrophysics Data System (ADS)
Ezawa, Motohiko
2017-07-01
Borophene is a monolayer materials made of boron. A perfect planar boropehene called β12 borophene has Dirac cones and they are well reproduced by a tight-binding model according to recent experimental and first-principles calculation results. We explicitly derive a Dirac theory for β12 borophene. Dirac cones are gapless when the inversion symmetry exists, while they are gapped when it is broken. In addition, three-band touching points emerge together with pseudospin triplet fermions when all transfer energy is equal and all onsite energy is equal. The three-band touching is slightly resolved otherwise. We construct effective three-band theories for triplet fermions. We also study the edge states of borophene nanoribbons, which show various behaviors depending on the way of edge terminations.
Chiral perturbation theory with nucleons
Meissner, U.G.
1991-09-01
I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external moments and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward-identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures of consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the methods. Some processes which are discussed are threshold photopion production, low-energy compton scattering off nucleons, {pi}N scattering and the {sigma}-term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon.
Numerical study of chiral plasma instability within the classical statistical field theory approach
NASA Astrophysics Data System (ADS)
Buividovich, P. V.; Ulybyshev, M. V.
2016-07-01
We report on a numerical study of real-time dynamics of electromagnetically interacting chirally imbalanced lattice Dirac fermions within the classical statistical field theory approach. Namely, we perform exact simulations of the real-time quantum evolution of fermionic fields coupled to classical electromagnetic fields, which are in turn coupled to the vacuum expectation value of the fermionic electric current. We use Wilson-Dirac Hamiltonian for fermions, and noncompact action for the gauge field. In general, we observe that the backreaction of fermions on the electromagnetic field prevents the system from acquiring chirality imbalance. In the case of chirality pumping in parallel electric and magnetic fields, the electric field is screened by the produced on-shell fermions and the accumulation of chirality is hence stopped. In the case of evolution with initially present chirality imbalance, axial charge tends to transform to helicity of the electromagnetic field. By performing simulations on large lattices we show that in most cases this decay process is accompanied by the inverse cascade phenomenon, which transfers energy from short-wavelength to long-wavelength electromagnetic fields. In some simulations, however, we observe a very clear signature of inverse cascade for the helical magnetic fields that is not accompanied by the axial charge decay. This suggests that the relation between the inverse cascade and axial charge decay is not as straightforward as predicted by the simplest form of anomalous Maxwell equations.
Elimination of spurious lattice fermion solutions and noncompact lattice QCD
Lee, T.D.
1997-09-22
It is well known that the Dirac equation on a discrete hyper-cubic lattice in D dimension has 2{sup D} degenerate solutions. The usual method of removing these spurious solutions encounters difficulties with chiral symmetry when the lattice spacing l {ne} 0, as exemplified by the persistent problem of the pion mass. On the other hand, we recall that in any crystal in nature, all the electrons do move in a lattice and satisfy the Dirac equation; yet there is not a single physical result that has ever been entangled with a spurious fermion solution. Therefore it should not be difficult to eliminate these unphysical elements. On a discrete lattice, particle hop from point to point, whereas in a real crystal the lattice structure in embedded in a continuum and electrons move continuously from lattice cell to lattice cell. In a discrete system, the lattice functions are defined only on individual points (or links as in the case of gauge fields). However, in a crystal the electron state vector is represented by the Bloch wave functions which are continuous functions in {rvec {gamma}}, and herein lies one of the essential differences.
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.
On a chiral analog of the Einstein-de Haas effect
Zakharov, V. I.
2015-03-15
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 scenario are discussed.
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.
Thermoelectric signature of the chiral anomaly in Cd3As2
Jia, Zhenzhao; Li, Caizhen; Li, Xinqi; Shi, Junren; Liao, Zhimin; Yu, Dapeng; Wu, Xiaosong
2016-01-01
Discovery of Weyl semimetals has revived interest in Weyl fermions which has not been observed in high energy experiments. It now becomes possible to study, in solids, their exotic properties. Extensive photoemission spectroscopy and electrical resistivity experiments have been carried out. However, many other properties remain unexplored. Here we show the thermoelectric signature of the chiral anomaly of Weyl fermions in Cd3As2 under a magnetic field. We observe a strong quadratic suppression of the thermopower when the magnetic field is parallel to the temperature gradient. The quadratic coefficient is nearly twice of that for the electrical conductivity. The thermopower reverses its sign in high fields. We show that all these intriguing observations can be understood in terms of the chiral anomaly of Weyl fermions. Our results reveal the anomalous thermoelectric property of Weyl fermions and provide insight into the chiral anomaly. PMID:27721372
Novel Fat-Link Fermion Actions
J. M. Zanotti; S. Bilson-Thompson; F. D. R. Bonnet; P. D. Coddington; D. B. Leinweber; A. G. Williams; J. B. Zhang; W. Melnitchouk; F. X. Lee
2001-07-01
The hadron mass spectrum is calculated in lattice QCD using a novel fat-link clover fermion action in which only the irrelevant operators in the fermion action are constructed using smeared links. The simulations are performed on a 16{sup 3} x 32 lattice with a lattice spacing of a=0.125 fm. We compare actions with n=4 and 12 smearing sweeps with a smearing fraction of 0.7. The n=4 Fat-Link Irrelevant Clover (FLIC) action provides scaling which is superior to mean-field improvement, and offers advantages over nonperturbative 0(a) improvement.
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.
Three-dimensional Pentagon Carbon with a genesis of emergent fermions.
Zhong, Chengyong; Chen, Yuanping; Yu, Zhi-Ming; Xie, Yuee; Wang, Han; Yang, Shengyuan A; Zhang, Shengbai
2017-06-05
Carbon, the basic building block of our universe, enjoys a vast number of allotropic structures. Owing to its bonding characteristic, most carbon allotropes possess the motif of hexagonal rings. Here, with first-principles calculations, we discover a new metastable three-dimensional carbon allotrope entirely composed of pentagon rings. The unique structure of this Pentagon Carbon leads to extraordinary electronic properties, making it a cornucopia of emergent topological fermions. Under lattice strain, Pentagon Carbon exhibits topological phase transitions, generating a series of novel quasiparticles, from isospin-1 triplet fermions to triply degenerate fermions and further to Hopf-link Weyl-loop fermions. Its Landau level spectrum also exhibits distinct features, including a huge number of almost degenerate chiral Landau bands, implying pronounced magneto-transport signals. Our work not only discovers a remarkable carbon allotrope with highly rare structural motifs, it also reveals a fascinating hierarchical particle genesis with novel topological fermions beyond the Dirac and Weyl paradigm.
Three-dimensional Pentagon Carbon with a genesis of emergent fermions
NASA Astrophysics Data System (ADS)
Zhong, Chengyong; Chen, Yuanping; Yu, Zhi-Ming; Xie, Yuee; Wang, Han; Yang, Shengyuan A.; Zhang, Shengbai
2017-06-01
Carbon, the basic building block of our universe, enjoys a vast number of allotropic structures. Owing to its bonding characteristic, most carbon allotropes possess the motif of hexagonal rings. Here, with first-principles calculations, we discover a new metastable three-dimensional carbon allotrope entirely composed of pentagon rings. The unique structure of this Pentagon Carbon leads to extraordinary electronic properties, making it a cornucopia of emergent topological fermions. Under lattice strain, Pentagon Carbon exhibits topological phase transitions, generating a series of novel quasiparticles, from isospin-1 triplet fermions to triply degenerate fermions and further to Hopf-link Weyl-loop fermions. Its Landau level spectrum also exhibits distinct features, including a huge number of almost degenerate chiral Landau bands, implying pronounced magneto-transport signals. Our work not only discovers a remarkable carbon allotrope with highly rare structural motifs, it also reveals a fascinating hierarchical particle genesis with novel topological fermions beyond the Dirac and Weyl paradigm.
Nikolai, Lisa N; McClure, Evelyn L; Macleod, Sherri L; Wong, Charles S
2006-10-27
A chiral liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method was developed and validated for measuring individual enantiomers of three beta-blocker drugs (atenolol, metoprolol, and propranolol) in wastewater treatment plant (WWTP) influents and effluents. Mean recoveries of the pharmaceuticals ranged from 67 to 106%, and the limits of detection of the analytes were 2-17 ng/L in wastewater effluents. The method was demonstrated by measuring, for the first time, the stereoisomer composition of target analytes in raw and treated wastewaters of two Canadian WWTPs. In these trials, racemic amounts of the three drugs were observed in influent of one wastewater treatment plant, but nonracemic amounts were observed in another. Effluents of the two plants contained nonracemic amounts of the drugs. These results indicate that biologically-mediated stereoselective processes that differ among WWTPs had occurred to eliminate individual enantiomers of the target analytes.
de la Puente, María Luz
2004-11-05
In the last years, there has been an increasing demand on the development of quantitative assays for determination of enantiopurity. Herein, we present a methodology based on a direct linking of an atmospheric pressure ionization mass spectrometer (MS-APCI) with a high-performance liquid chromatography HPLC (DAD) system, operated under normal-phase mode and without post-column addition of MS-compatible solvents, which provides the high specificity/selectivity (identification of isomers in complex mixtures) and accuracy (1-2% area level) required for daily chiral studies. As result of the success of our screen, the preparation of individual enantiomers or the racemic mixture in our Drug Discovery Research Laboratories at Lilly, Spain is usually not required. Therefore, additional non-valuable synthetic work is eliminated.
Fermions on one or fewer kinks
Chu Yizen; Vachaspati, Tanmay
2008-01-15
We find the full spectrum of fermion bound states on a Z{sub 2} kink. In addition to the zero mode, there are int[2m{sub f}/m{sub s}] bound states, where m{sub f} is the fermion and m{sub s} the scalar mass. We also study fermion modes on the background of a well-separated kink-antikink pair. Using a variational argument, we prove that there is at least one bound state in this background, and that the energy of this bound state goes to zero with increasing kink-antikink separation, 2L, and faster than e{sup -a2L} where a=min(m{sub s},2m{sub f}). By numerical evaluation, we find some of the low lying bound states explicitly.
NASA Astrophysics Data System (ADS)
Luo, Cui-Bai; Shi, Song; Xia, Yong-Hui; Zong, Hong-Shi
2017-06-01
The Eigenstate Method has been developed to deduce the fermion propagator with a constant external magnetic field. In general, we find its result is equivalent to other methods and this new method is more convenient, especially when one evaluates the contribution from the infinitesimal imaginary term of the fermion propagator. Using the Eigenstate Method we try to discuss whether the infinitesimal imaginary frequency of the fermion propagator in a strong magnetic field and Lorentz-violating extension of the minimal SU(3)×SU(2)×SU(1) Standard Model could have a significant influence on the dynamical mass. When the imaginary term of the fermion propagator in this model is not trivial , this model gives a correction to the dynamical mass. When one does not consider the influence from the imaginary term , there is another correction from the conventional term. Under both circumstances, chiral symmetry is broken. Supported in part by National Natural Science Foundation of China (11275097, 11475085, 11535005, 11690030), China Postdoctoral Science Foundation (2014M561621), and Jiangsu Planned Projects for Postdoctoral Research Funds (1401116C)
Effective theory of chiral two-dimensional superfluids
NASA Astrophysics Data System (ADS)
Hoyos, Carlos; Moroz, Sergej; Son, Dam Thanh
2014-05-01
We construct, to leading orders in the momentum expansion, an effective theory of a chiral (px+ipy) two-dimensional fermionic superfluid at zero temperature that is consistent with nonrelativistic general coordinate invariance. This theory naturally incorporates the parity and time-reversal violating effects such as the Hall viscosity and the edge current. The particle number current and stress tensor are computed and their linear response to electromagnetic and gravitational sources is calculated. We also consider an isolated vortex in a chiral superfluid and identify the leading chirality effect in the density depletion profile.
Approximation of fermion resonances on a splitting domain wall
NASA Astrophysics Data System (ADS)
Farokhtabar, A.; Tofighi, A.
2017-08-01
In this paper the splitting of a domain wall is investigated analytically in flat spacetime. We also study fermion localization and resonances on this domain wall. Masses of Kaluza-Klein modes determined by two methods, numerical method and approximation one. We observe that the agreement between approximated values and numeric ones is good. It is found that the number of fermion resonances on the brane is increased with mass parameter.
Response of fermions in Chern bands to spatially local quenches
NASA Astrophysics Data System (ADS)
Grushin, Adolfo G.; Roy, Sthitadhi; Haque, Masudul
2016-08-01
We study the dynamical evolution of Chern-band systems after subjecting them to local quenches. For open-boundary systems, we show for half-filling that the chiral nature of edge states is manifested in the time-dependent chiral response to local density quenches on the edge. In the presence of power-law traps, we show how to mimic the half-filling situation by choosing the appropriate number of fermions depending on the trap size, and explore chiral responses of edges to local quenches in such a configuration. We find that perturbations resulting from the quenches propagate at smaller group velocities as the gap controlling the spatial extent of the edge modes decreases. Our results provide different routes to check dynamically the non-trivial nature of Chern bands.
Stable pentaquarks from strange chiral multiplets
Beane, Silas R.
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. 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.
Stable Pentaquarks from Strange Chiral Multiplets
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. 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.
Consistent quantization of massive chiral electrodynamics in four dimensions
Andrianov, A. ); Bassetto, A.; Soldati, R.
1989-10-09
We discuss the quantization of a four-dimensional model in which a massive Abelian vector field interacts with chiral massless fermions. We show that, by introducing extra scalar fields, a renormalizable unitary {ital S} matrix can be obtained in a suitably defined Hilbert space of physical states.
NASA Astrophysics Data System (ADS)
Mekki-Berrada, Ali
Bringing closer phospholipids each other on a bilayer of liposome, causes their rotation around their fatty acids axis, generating a force which brings closer the two sheets of the bilayer. In this theoretical study I show that for getting the greater cohesion of the liposome, by these forces, the serine in the hydrophilic head must have a L chirality. In the case where the hydrophilic head is absent amino acids with L chirality could contribute to this cohesion by taking the place of L-serine. Some coenzymes having a configuration similar to ethanolamine may also contribute. This is the case of pyridoxamine, thiamine and tetrahydrofolic acid. The grouping of amino acids of L chirality and pyridoxamine on the wall could initialize the prebiotic metabolism of these L amino acids only. This would explain the origin of the homo-chirality of amino acids in living world. Furthermore I show that in the hydrophilic head, the esterification of glycerol-phosphate by two fatty acids go through the positioning of dihydroxyacetone-phosphate and L-glyceraldehyde-3-phosphate, but not of D-glyceraldehyde-3-phosphate, prior their hydrogenation to glycerol-3- phosphate. The accumulation of D-glyceraldehyde-3-phosphate in the cytoplasm displace the thermodynamic equilibria towards the synthesis of D-dATP from D-glyceraldehyde-3-phosphate, acetaldehyde and prebiotic adenine, a reaction which does not require a coenzyme in the biotic metabolism. D-dATP and thiamine, more prebiotic metabolism of L-amino acids on the wall, would initialize D-pentoses phosphate and D-nucleotides pathways from the reaction of D-glyceraldehyde-3-phosphate + dihydroxyacetone-phosphate + prebiotic nucleic bases. The exhaustion of the prebiotic glyceraldehyde (racemic) and the nascent biotic metabolism dominated by D-glyceraldehyde-3-phosphate, would explain the origin of homo-chirality of sugars in living world. References: http://en.wikiversity.org/wiki/Prebiotic_chirality
Conformal manifolds in four dimensions and chiral algebras
NASA Astrophysics Data System (ADS)
Buican, Matthew; Nishinaka, Takahiro
2016-11-01
Any { N }=2 superconformal field theory (SCFT) in four dimensions has a sector of operators related to a two-dimensional chiral algebra containing a Virasoro sub-algebra. Moreover, there are well-known examples of isolated SCFTs whose chiral algebra is a Virasoro algebra. In this note, we consider the chiral algebras associated with interacting { N }=2 SCFTs possessing an exactly marginal deformation that can be interpreted as a gauge coupling (i.e., at special points on the resulting conformal manifolds, free gauge fields appear that decouple from isolated SCFT building blocks). At any point on these conformal manifolds, we argue that the associated chiral algebras possess at least three generators. In addition, we show that there are examples of SCFTs realizing such a minimal chiral algebra: they are certain points on the conformal manifold obtained by considering the low-energy limit of type IIB string theory on the three complex-dimensional hypersurface singularity {x}13+{x}23+{x}33+α {x}1{x}2{x}3+{w}2=0. The associated chiral algebra is the { A }(6) theory of Feigin, Feigin, and Tipunin. As byproducts of our work, we argue that (i) a collection of isolated theories can be conformally gauged only if there is a SUSY moduli space associated with the corresponding symmetry current moment maps in each sector, and (ii) { N }=2 SCFTs with a≥slant c have hidden fermionic symmetries (in the sense of fermionic chiral algebra generators).
1984-10-01
TITLE (mid Subttlo) -JS. TYPE OF REPORT & PERIOD COVERED CHIRAL POLYMERS /~O~~ R E~NNE 7. AUTHOR(e) 11. CONTRACT OR GRANT NUNSIER(e) J. K. Stille...acrylamide monomer containing a chiral 1,3-dioxane unit as well as both racemic and ( R )-6.-methyl ene-vi-methyl -7-butyrol actone were synthesi zed...or ( R )-propylene oxide (10)6. The key step in this synthesis is the palladium catalyzed carbonylation of 4-bromopent-4-en-2-ol. Thus, either racemic or
Scattering of fermions by gravitons
NASA Astrophysics Data System (ADS)
Ulhoa, S. C.; Santos, A. F.; Khanna, Faqir C.
2017-04-01
The interaction between gravitons and fermions is investigated in the teleparallel gravity. The scattering of fermions and gravitons in the weak field approximation is analyzed. The transition amplitudes of M\\varnothing ller, Compton and new gravitational scattering are calculated.
Kalos, M. H.; Pederiva, F.
1998-12-01
We review the fundamental challenge of fermion Monte Carlo for continuous systems, the "sign problem". We seek that eigenfunction of the many-body Schriodinger equation that is antisymmetric under interchange of the coordinates of pairs of particles. We describe methods that depend upon the use of correlated dynamics for pairs of correlated walkers that carry opposite signs. There is an algorithmic symmetry between such walkers that must be broken to create a method that is both exact and as effective as for symmetric functions, In our new method, it is broken by using different "guiding" functions for walkers of opposite signs, and a geometric correlation between steps of their walks, With a specific process of cancellation of the walkers, overlaps with antisymmetric test functions are preserved. Finally, we describe the progress in treating free-fermion systems and a fermion fluid with 14 ^{3}He atoms.
Chiral phases of fundamental and adjoint quarks
Natale, A. A.
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.
Chiral phases of fundamental and adjoint quarks
NASA Astrophysics Data System (ADS)
Natale, A. A.
2016-01-01
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 (nf ≈ 11 - 13) in agreement with lattice data.
Chiral symmetry and pentaquarks
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.