Chiral matrix model of the semi-QGP in QCD

DOE PAGES

Pisarski, Robert D.; Skokov, Vladimir V.

2016-08-08

Previously, a matrix model of the region near the transition temperature, in the “semi”quark gluon plasma, was developed for the theory of SU(3) gluons without quarks. In this paper we develop a chiral matrix model applicable to QCD by including dynamical quarks with 2+1 flavors. This requires adding a nonet of scalar fields, with both parities, and coupling these to quarks through a Yukawa coupling, y. Treating the scalar fields in mean field approximation, the effective Lagrangian is computed by integrating out quarks to one loop order. As is standard, the potential for the scalar fields is chosen to bemore » symmetric under the flavor symmetry of SU (3) L × SU(3) R × Z (3) A , except for a term linear in the current quark mass, m qk . In addition, at a nonzero temperature T it is necessary to add a new term, ~ m qk T 2 . The parameters of the gluon part of the matrix model are identical to those for the pure glue theory without quarks. The parameters in the chiral matrix model are fixed by the values, at zero temperature, of the pion decay constant and the masses of the pions, kaons, η , and η' . The temperature for the chiral crossover at T$χ$ = 155 MeV is determined by adjusting the Yukawa coupling y . We find reasonable agreement with the results of numerical simulations on the lattice for the pressure and related quantities. In the chiral limit, besides the divergence in the chiral susceptibility there is also a milder divergence in the susceptibility between the Polyakov loop and the chiral order parameter, with critical exponent β $-$ 1 . We compute derivatives with respect to a quark chemical potential to determine the susceptibilities for baryon number, the $χ$ 2n . Especially sensitive tests are provided by $χ$ 4 $-$ $χ$ 2 and by $χ$ 6 , which changes in sign about T$χ$ . In conclusion, the behavior of the susceptibilities in the chiral matrix model strongly suggests that as the temperature increases from T$χ$ , that the transition to

Excited meson spectroscopy with two chirally improved quarks

NASA Astrophysics Data System (ADS)

Engel, G.; Lang, C. B.; Mohler, D.; Limmer, M.; Schäfer, A.

The excited isovector meson spectrum is explored using two chirally improved dynamical quarks. Seven ensembles, with pion masses down to \\approx 250 MeV are discussed and used for extrapolations to the physical point. Strange mesons are investigated using partially quenched s-quarks. Using the variational method, we extract excited states in several channels and most of the results are in good agreement with experiment.

Flavor structure of the nucleon electromagnetic form factors and transverse charge densities in the chiral quark-soliton model

NASA Astrophysics Data System (ADS)

Silva, António; Urbano, Diana; Kim, Hyun-Chul

2018-02-01

We investigate the flavor decomposition of the electromagnetic form factors of the nucleon, based on the chiral quark-soliton model (χQSM) with symmetry-conserving quantization. We consider the rotational 1/N_c and linear strange-quark mass (ms) corrections. We discuss the results of the flavor-decomposed electromagnetic form factors in comparison with the recent experimental data. In order to see the effects of the strange quark, we compare the SU(3) results with those of SU(2). Finally, we discuss the transverse charge densities for both unpolarized and polarized nucleons. The transverse charge density inside a neutron turns out to be negative in the vicinity of the center within the SU(3) χQSM, which can be explained by the contribution of the strange quark.

Chiral Lagrangian with Heavy Quark-Diquark Symmetry

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

Jie Hu; Thomas Mehen

2005-11-29

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

Heavy and Light Quarks with Lattice Chiral Fermions

NASA Astrophysics Data System (ADS)

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

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

Electromagnetic form factors of singly heavy baryons in the self-consistent SU(3) chiral quark-soliton model

NASA Astrophysics Data System (ADS)

Kim, June-Young; Kim, Hyun-Chul

2018-06-01

The self-consistent chiral quark-soliton model is a relativistic pion mean-field approach in the large Nc limit, which describes both light and heavy baryons on an equal footing. In the limit of the infinitely heavy mass of the heavy quark, a heavy baryon can be regarded as Nc-1 valence quarks bound by the pion mean fields, leaving the heavy quark as a color static source. The structure of the heavy baryon in this scheme is mainly governed by the light-quark degrees of freedom. Based on this framework, we evaluate the electromagnetic form factors of the lowest-lying heavy baryons. The rotational 1 /Nc and strange current quark mass corrections in linear order are considered. We discuss the electric charge and magnetic densities of heavy baryons in comparison with those of the nucleons. The results of the electric charge radii of the positive-charged heavy baryons show explicitly that the heavy baryon is a compact object. The electric form factors are presented. The form factor of Σc++ is compared with that from a lattice QCD. We also discuss the results of the magnetic form factors. The magnetic moments of the baryon sextet with spin 1 /2 and the magnetic radii are compared with other works and the lattice data.

Dense baryon matter with isospin and chiral imbalance in the framework of a NJL4 model at large Nc: Duality between chiral symmetry breaking and charged pion condensation

NASA Astrophysics Data System (ADS)

Khunjua, T. G.; Klimenko, K. G.; Zhokhov, R. N.

2018-03-01

In this paper the phase structure of dense quark matter has been investigated at zero temperature in the presence of baryon, isospin and chiral isospin chemical potentials in the framework of massless (3 +1 )-dimensional Nambu-Jona-Lasinio model with two quark flavors. It has been shown that in the large-Nc limit (Nc is the number of colors of quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation one. The key conclusion of our studies is the fact that chiral isospin chemical potential generates charged pion condensation in dense quark matter with isotopic asymmetry.

Strange-quark asymmetry in the proton in chiral effective theory

DOE PAGES

Wang, X. G.; Ji, Chueng -Ryong; Melnitchouk, W.; ...

2016-11-29

We perform a comprehensive analysis of the strange-antistrange parton distribution function (PDF) asymmetry in the proton in the framework of chiral effective theory, including the full set of lowest-order kaon loop diagrams with off-shell and contact interactions, in addition to the usual on-shell contributions previously discussed in the literature. We identify the presence of δ-function contributions to the s¯ PDF at x = 0, with a corresponding valencelike component of the s-quark PDF at larger x, which allows greater flexibility for the shape of s–s¯. Expanding the moments of the PDFs in terms of the pseudoscalar kaon mass, we computemore » the leading nonanalytic behavior of the number and momentum integrals of the s and s¯ distributions, consistent with the chiral symmetry of QCD. Lastly, we discuss the implications of our results for the understanding of the NuTeV anomaly and for the phenomenology of strange-quark PDFs in global QCD analysis.« less

Chiral Odd Structure Functions in The Nambu--Jona--Lasinio Soliton Model

NASA Astrophysics Data System (ADS)

Gamberg, Leonard; Reinhardt, Hugo; Weigel, Herbert

1998-10-01

We study unpolarized and polarized nucleon structure functions(H. Weigel, L. Gamberg, and H. Reinhardt, Mod. Phys. Lett. A11) (1996) 3021; Phys. Lett. B399 (1997) 287;Phys. Rev. D55(1997) 6910. within the bosonized Nambu--Jona--Lasinio (NJL) model where the nucleon emerges as a chiral soliton(R. Alkofer, H. Reinhardt and H. Weigel, Phys. Rep. 265) (1996) 139.. These considerations attempt to merge the parton model description of deep inelastic scattering with the phenomenologically successful picture of baryons as chiral solitons. In addition we report on the calculation of the chiral odd quark distributions(L. Gamberg, H. Reinhardt and H. Weigel, "Chiral odd structure functions from a chiral soliton", hep-ph/9801379, Phys. Rev. D. in press.) and the corresponding structure functions h_T(x,Q^2) and h_L(x,Q^2). At the low model scale, Q_0^2, we find that the leading twist effective quark distributions, f_1^(q)(x,Q_0^2), g_1^(q)(x,Q_0^2) and h_T^(q)(x,Q_0^2) satisfy Soffer's inequality for both quark flavors q=u,d. The Q^2 evolution of the twist--2 contributions is performed according to the standard GLAP formalism while the twist--three pieces, \\overlineg_2(x) and \\overlineh_L(x), are evolved according to the large NC scheme.

Dibaryons with Strangeness in Quark Models

NASA Astrophysics Data System (ADS)

Chen, Mei; Gong, Fang; Huang, Hongxia; Ping, Jialun

The extended quark delocalization color screening model, which incorporates Goldstone-boson-exchange with soft cutoff, and chiral quark model are employed to do a systematic dynamical calculation of six-quark systems with strangeness. The two models give similar results, although they have different attraction mechanisms. Comparing with the previous calculation of the extended quark delocalization color screening model, in which the Goldstone-bosons are introduced with hard cutoff, the present calculation obtains a little large binding energies for most of the states. However, the conclusions are the same. The calculations show that NΩ state with IJ = 1/2, 2 is a good dibaryon candidate with narrow width, and ΩΩ state with IJ = 00 is a stable dibaryon against the strong interaction. The calculations also reveal several other possible dibaryon candidates with high angular momentum, ΔΣ*(1/2, 3), ΔΞ*(1, 3), etc. These states may have too wide width to be observed experimentally.

Light-meson masses in an unquenched quark model

NASA Astrophysics Data System (ADS)

Chen, Xiaoyun; Ping, Jialun; Roberts, Craig D.; Segovia, Jorge

2018-05-01

We perform a coupled-channels calculation of the masses of light mesons with the quantum numbers I JP =-, (I ,J )=0 , 1, by including q q ¯ and (q q ¯)2 components in a nonrelativistic chiral quark model. The coupling between two- and four-quark configurations is realized through a 3P0 quark-pair creation model. With the usual form of this operator, the mass shifts are large and negative, an outcome which raises serious issues of validity for the quenched quark model. Herein, therefore, we introduce some improvements of the 3P0 operator in order to reduce the size of the mass shifts. By introducing two simple factors, physically well motivated, the coupling between q q ¯ and (q q ¯)2 components is weakened, producing mass shifts that are around 10%-20% of hadron bare masses.

Vector and Axial-Vector Correlators in AN Instanton-Like Quark Model

NASA Astrophysics Data System (ADS)

Dorokhov, Alexander E.

The behavior of the vector Adler function at spacelike momenta is studied in the framework of a covariant chiral quark model with instanton-like quark-quark interaction. This function describes the transition between the high energy asymptotically free region of almost massless current quarks to the low energy hadronized regime with massive constituent quarks. The model reproduces the Adler function and V-A correlator extracted from the ALEPH and OPAL data on hadronic τ lepton decays, transformed into the Euclidean domain via dispersion relations. The leading order contribution from hadronic part of the photon vacuum polarization to the anomalous magnetic moment of the muon, aμ hvp(1), is estimated.

QCD with two light dynamical chirally improved quarks: Mesons

NASA Astrophysics Data System (ADS)

Engel, Georg P.; Lang, C. B.; Limmer, Markus; Mohler, Daniel; Schäfer, Andreas

2012-02-01

We present results for the spectrum of light and strange mesons on configurations with two flavors of mass-degenerate Chirally Improved sea quarks. The calculations are performed on seven ensembles of lattice size 163×32 at three different gauge couplings and with pion masses ranging from 250 to 600 MeV. To reliably extract excited states, we use the variational method with an interpolator basis containing both Gaussian and derivative quark sources. Both conventional and exotic channels up to spin 2 are considered. Strange quarks are treated within the partially quenched approximation. For kaons we investigate the mixing of interpolating fields corresponding to definite C-parity in the SU(3) limit. This enlarged basis allows for an improved determination of the low-lying kaon spectrum. In addition to masses we also extract the ratio of the pseudoscalar decay constants of the kaon and pion and obtain FK/Fπ=1.215(41). The results presented here include some ensembles from previous publications and the corresponding results supersede the previously published values.

Light-meson masses in an unquenched quark model

DOE PAGES

Chen, Xiaoyun; Ping, Jialun; Roberts, Craig D.; ...

2018-05-17

We perform a coupled-channels calculation of the masses of light mesons with the quantum numbers IJ P=-, (I,J) = 0,1, by includingmore » $$q\\bar{q}$$ and ($$q\\bar{q}$$) 2 components in a nonrelativistic chiral quark model. The coupling between two- and four-quark configurations is realized through a 3P 0 quark-pair creation model. With the usual form of this operator, the mass shifts are large and negative, an outcome which raises serious issues of validity for the quenched quark model. Therefore, we introduce some improvements of the 3P 0 operator in order to reduce the size of the mass shifts. By introducing two simple factors, physically well motivated, the coupling between $$q\\bar{q}$$ and ($$q\\bar{q}$$) 2 components is weakened, producing mass shifts that are around 10%–20% of hadron bare masses.« less

Light-meson masses in an unquenched quark model

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

Chen, Xiaoyun; Ping, Jialun; Roberts, Craig D.

We perform a coupled-channels calculation of the masses of light mesons with the quantum numbers IJ P=-, (I,J) = 0,1, by includingmore » $$q\\bar{q}$$ and ($$q\\bar{q}$$) 2 components in a nonrelativistic chiral quark model. The coupling between two- and four-quark configurations is realized through a 3P 0 quark-pair creation model. With the usual form of this operator, the mass shifts are large and negative, an outcome which raises serious issues of validity for the quenched quark model. Therefore, we introduce some improvements of the 3P 0 operator in order to reduce the size of the mass shifts. By introducing two simple factors, physically well motivated, the coupling between $$q\\bar{q}$$ and ($$q\\bar{q}$$) 2 components is weakened, producing mass shifts that are around 10%–20% of hadron bare masses.« less

QCD with Chiral Imbalance: models vs. lattice

NASA Astrophysics Data System (ADS)

Andrianov, Alexander; Andrianov, Vladimir; Espriu, Domenec

2017-03-01

In heavy ion collisions (HIC) at high energies there may appear new phases of matter which must be described by QCD. These phases may have different color and flavour symmetries associated with the constituents involved in collisions as well as various space-time symmetries of hadron matter. Properties of the QCD medium in such a matter can be approximately described, in particular, by a number of right-handed (RH) and left-handed (LH) light quarks. The chiral imbalance (ChI) is characterized by the difference between the numbers of RH and LH quarks and supposedly occurs in the fireball after HIC. Accordingly we have to introduce a quark chiral (axial) chemical potential which simulates a ChI emerging in such a phase. In this report we discuss the possibility of a phase with Local spatial Parity Breaking (LPB) in such an environment and outline conceivable signatures for the registration of LPB as well as the appearance of new states in the spectra of scalar, pseudoscalar and vector particles as a consequence of local ChI. The comparison of the results obtained in the effective QCD- motivated models with lattice data is also performed.

Effects of Fluctuations on Inhomogeneous Chiral Transitions

NASA Astrophysics Data System (ADS)

Lee, Tong-Gyu; Yoshiike, Ryo; Tatsumi, Toshitaka

We discuss the features of the order-parameter fluctuations in the normal phase near the phase boundary and their effects on the phase transition from the normal to the inhomogeneous phase with spatially modulated order parameter. Focusing on the chiral symmetry breaking, i.e., inhomogeneous chiral transition, we consider the fluctuation of the chiral pair consisting of quark-antiquark or quark-hole pair within the two-flavor Nambu-Jona-Lasinio model in the chiral limit. We clarify the roles of quantum and thermal fluctuations and also argue that anomalies for thermodynamic quantities in the inhomogeneous chiral transition should lead to phenomenological implications.

Fluid-gravity model for the chiral magnetic effect.

PubMed

Kalaydzhyan, Tigran; Kirsch, Ingo

2011-05-27

We consider the STU model as a gravity dual of a strongly coupled plasma with multiple anomalous U(1) currents. In the bulk we add additional background gauge fields to include the effects of external electric and magnetic fields on the plasma. Reducing the number of chemical potentials in the STU model to two and interpreting them as quark and chiral chemical potential, we obtain a holographic description of the chiral magnetic and chiral vortical effects (CME and CVE) in relativistic heavy-ion collisions. These effects formally appear as first-order transport coefficients in the electromagnetic current. We compute these coefficients from our model using fluid-gravity duality. We also find analogous effects in the axial-vector current. Finally, we briefly discuss a variant of our model, in which the CME/CVE is realized in the late-time dynamics of an expanding plasma. © 2011 American Physical Society

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

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

Chiral gravitational waves and baryon superfluid dark matter

NASA Astrophysics Data System (ADS)

Alexander, Stephon; McDonough, Evan; Spergel, David N.

2018-05-01

We develop a unified model of darkgenesis and baryogenesis involving strongly interacting dark quarks, utilizing the gravitational anomaly of chiral gauge theories. In these models, both the visible and dark baryon asymmetries are generated by the gravitational anomaly induced by the presence of chiral primordial gravitational waves. We provide a concrete model of an SU(2) gauge theory with two massless quarks. In this model, the dark quarks condense and form a dark baryon charge superfluid (DBS), in which the Higgs-mode acts as cold dark matter. We elucidate the essential features of this dark matter scenario and discuss its phenomenological prospects.

The chiral quark condensate and pion decay constant in nuclear matter at next-to-leading order

NASA Astrophysics Data System (ADS)

Lacour, A.; Oller, J. A.; Meißner, U.-G.

2010-12-01

Making use of the recently developed chiral power counting for the physics of nuclear matter (Oller et al 2010 J. Phys. G: Nucl. Part. Phys. 37 015106, Lacour et al Ann. Phys. at press), we evaluate the in-medium chiral quark condensate up to next-to-leading order for both symmetric nuclear matter and neutron matter. Our calculation includes the full in-medium iteration of the leading order local and one-pion exchange nucleon-nucleon interactions. Interestingly, we find a cancellation between the contributions stemming from the quark mass dependence of the nucleon mass appearing in the in-medium nucleon-nucleon interactions. Only the contributions originating from the explicit quark mass dependence of the pion mass survive. This cancellation is the reason of previous observations concerning the dominant role of the long-range pion contributions and the suppression of short-range nucleon-nucleon interactions. We find that the linear density contribution to the in-medium chiral quark condensate is only slightly modified for pure neutron matter by the nucleon-nucleon interactions. For symmetric nuclear matter, the in-medium corrections are larger, although smaller compared to other approaches due to the full iteration of the lowest order nucleon-nucleon tree-level amplitudes. Our calculation satisfies the Hellmann-Feynman theorem to the order worked out. Also we address the problem of calculating the leading in-medium corrections to the pion decay constant. We find that there are no extra in-medium corrections that violate the Gell-Mann-Oakes-Renner relation up to next-to-leading order.

Effects of Composite Pions on the Chiral Condensate within the PNJL Model at Finite Temperature

NASA Astrophysics Data System (ADS)

Blaschke, D.; Dubinin, A.; Ebert, D.; Friesen, A. V.

2018-05-01

We investigate the effect of composite pions on the behaviour of the chiral condensate at finite temperature within the Polyakov-loop improved NJL model. To this end we treat quark-antiquark correlations in the pion channel (bound states and scattering continuum) within a Beth-Uhlenbeck approach that uses medium-dependent phase shifts. A striking medium effect is the Mott transition which occurs when the binding energy vanishes and the discrete pion bound state merges the continuum. This transition is triggered by the lowering of the continuum edge due to the chiral restoration transition. This in turn also entails a modification of the Polyakov-loop so that the SU(3) center symmetry gets broken at finite temperature and dynamical quarks (and gluons) appear in the system, taking over the role of the dominant degrees of freedom from the pions. At low temperatures our model reproduces the chiral perturbation theory result for the chiral condensate while at high temperatures the PNJL model result is recovered. The new aspect of the current work is a consistent treatment of the chiral restoration transition region within the Beth-Uhlenbeck approach on the basis of mesonic phase shifts for the treatment of the correlations.

Lattice QCD analysis for relation between quark confinement and chiral symmetry breaking

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

Doi, Takahiro M.; Suganuma, Hideo; Iritani, Takumi

2016-01-22

The Polyakov loop and the Dirac modes are connected via a simple analytical relation on the temporally odd-number lattice, where the temporal lattice size is odd with the normal (nontwisted) periodic boundary condition. Using this relation, we investigate the relation between quark confinement and chiral symmetry breaking in QCD. In this paper, we discuss the properties of this analytical relation and numerically investigate each Dirac-mode contribution to the Polyakov loop in both confinement and deconfinement phases at the quenched level. This relation indicates that low-lying Dirac modes have little contribution to the Polyakov loop, and we numerically confirmed this fact.more » From our analysis, it is suggested that there is no direct one-to-one corresponding between quark confinement and chiral symmetry breaking in QCD. Also, in the confinement phase, we numerically find that there is a new “positive/negative symmetry” in the Dirac-mode matrix elements of link-variable operator which appear in the relation and the Polyakov loop becomes zero because of this symmetry. In the deconfinement phase, this symmetry is broken and the Polyakov loop is non-zero.« less

Chiral drag force

DOE PAGES

Rajagopal, Krishna; Sadofyev, Andrey V.

2015-10-05

Here, we provide a holographic evaluation of novel contributions to the drag force acting on a heavy quark moving through strongly interacting plasma. The new contributions are chiral in the sense that they act in opposite directions in plasmas containing an excess of left- or right-handed quarks. The new contributions are proportional to the coefficient of the axial anomaly, and in this sense also are chiral. These new contributions to the drag force act either parallel to or antiparallel to an external magnetic field or to the vorticity of the fluid plasma. In all these respects, these contributions to themore » drag force felt by a heavy quark are analogous to the chiral magnetic effect (CME) on light quarks. However, the new contribution to the drag force is independent of the electric charge of the heavy quark and is the same for heavy quarks and antiquarks, meaning that these novel effects do not in fact contribute to the CME current. We show that although the chiral drag force can be non-vanishing for heavy quarks that are at rest in the local fluid rest frame, it does vanish for heavy quarks that are at rest in a suitably chosen frame. In this frame, the heavy quark at rest sees counterpropagating momentum and charge currents, both proportional to the axial anomaly coefficient, but feels no drag force. This provides strong concrete evidence for the absence of dissipation in chiral transport, something that has been predicted previously via consideration of symmetries. Along the way to our principal results, we provide a general calculation of the corrections to the drag force due to the presence of gradients in the flowing fluid in the presence of a nonzero chemical potential. We close with a consequence of our result that is at least in principle observable in heavy ion collisions, namely an anticorrelation between the direction of the CME current for light quarks in a given event and the direction of the kick given to the momentum of all the heavy

Positivity bound on the imaginary part of the right-chiral tensor coupling gR in polarized top quark decay

NASA Astrophysics Data System (ADS)

Groote, S.; Körner, J. G.

2017-12-01

We derive a positivity bound on the right-chiral tensor coupling Im gR in polarized top quark decay by analyzing the angular decay distribution of the three-body polarized top quark decay t (↑)→b +ℓ++νℓ in next-to-leading order QCD. We obtain the bound -0.0420 ≤Im gR≤0.0420 .

Confronting effective models for deconfinement in dense quark matter with lattice data

NASA Astrophysics Data System (ADS)

Andersen, Jens O.; Brauner, Tomáš; Naylor, William R.

2015-12-01

Ab initio numerical simulations of the thermodynamics of dense quark matter remain a challenge. Apart from the infamous sign problem, lattice methods have to deal with finite volume and discretization effects as well as with the necessity to introduce sources for symmetry-breaking order parameters. We study these artifacts in the Polyakov-loop-extended Nambu-Jona-Lasinio (PNJL) model and compare its predictions to existing lattice data for cold and dense two-color matter with two flavors of Wilson quarks. To achieve even qualitative agreement with lattice data requires the introduction of two novel elements in the model: (i) explicit chiral symmetry breaking in the effective contact four-fermion interaction, referred to as the chiral twist, and (ii) renormalization of the Polyakov loop. The feedback of the dense medium to the gauge sector is modeled by a chemical-potential-dependent scale in the Polyakov-loop potential. In contrast to previously used analytical Ansätze, we determine its dependence on the chemical potential from lattice data for the expectation value of the Polyakov loop. Finally, we propose adding a two-derivative operator to our effective model. This term acts as an additional source of explicit chiral symmetry breaking, mimicking an analogous term in the lattice Wilson action.

Quark-hadron phase structure of QCD matter from SU(4) Polyakov linear sigma model

NASA Astrophysics Data System (ADS)

Diab, Abdel Magied Abdel Aal; Tawfik, Abdel Nasser

2018-04-01

The SU(4) Polyakov linear sigma model (PLSM) is extended towards characterizing the chiral condensates, σl, σs and σc of light, strange and charm quarks, respectively and the deconfinement order-parameters φ and φ at finite temperatures and densities (chemical potentials). The PLSM is considered to study the QCD equation of state in the presence of the chiral condensate of charm for different finite chemical potentials. The PLSM results are in a good agreement with the recent lattice QCD simulations. We conclude that, the charm condensate is likely not affected by the QCD phase-transition, where the corresponding critical temperature is greater than that of the light and strange quark condensates.

Heavy-light mesons in chiral AdS/QCD

NASA Astrophysics Data System (ADS)

Liu, Yizhuang; Zahed, Ismail

2017-06-01

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

Magnetic fields in turbulent quark matter and magnetar bursts

NASA Astrophysics Data System (ADS)

Dvornikov, Maxim

We analyze the magnetic field evolution in dense quark matter with unbroken chiral symmetry, which can be found inside quark and hybrid stars. The magnetic field evolves owing to the chiral magnetic effect in the presence of the electroweak interaction between quarks. In our study, we also take into account the magnetohydrodynamic turbulence effects in dense quark matter. We derive the kinetic equations for the spectra of the magnetic helicity density and the magnetic energy density as well as for the chiral imbalances. On the basis of the numerical solution of these equations, we find that turbulence effects are important for the behavior of small scale magnetic fields. It is revealed that, under certain initial conditions, these magnetic fields behave similarly to the electromagnetic flashes of some magnetars. We suggest that fluctuations of magnetic fields, described in frames of our model, which are created in the central regions of a magnetized compact star, can initiate magnetar bursts.

Chiral symmetry and pentaquarks

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

Dmitri Diakonov

2004-07-01

Spontaneous chiral symmetry breaking, mesons and baryons are illustrated in the language of the Dirac theory. Various forces acting between quarks inside baryons are discussed. I explain why the naive quark models typically overestimate pentaquark masses by some 500 MeV and why in the fully relativistic approach to baryons pentaquarks turn out to be light. I discuss briefly why it can be easier to produce pentaquarks at low than at high energies.

Centre vortex removal restores chiral symmetry

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Centre vortex removal restores chiral symmetry

DOE PAGES

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

2017-11-15

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

Mended chiral symmetry and the linear sigma model in one-loop order

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

Scadron, M.D.

1992-02-28

In this paper it is shown that the linear {sigma}-model in one loop order in the chiral limit recovers meson masses m{sub {pi}} = 0, m{sub {sigma}} = 2m{sub qk} (NJL), m {sub {rho}} = {radical}2 g{sub {rho}}f{pi} (KSRF), along with couplings g{sigma}{pi}{pi} = m{sup 2}{sub {sigma}}/2f{pi}, g{rho}{pi}{pi} = g{sub {rho}} (VMD universality) and Weinberg's mended chiral symmetry decay width relation {Gamma}{sub {sigma}} = (9/2){Gamma}{sub {rho}}. The linear {sigma}-model combined quark and meson loops also properly predict the radiative decays {pi}{sup 0} {yields} 2{gamma} {yields} e{nu}{gamma} and {delta}{sup 0} (983) {yields} 2{gamma}.

Search for the Chiral Magnetic Effect in Heavy-Ion Collisions and Quantification of the Background with the AMPT Model

NASA Astrophysics Data System (ADS)

Bryon, Jacob

2017-09-01

The chiral magnetic effect (CME) arises from the chirality imbalance of quarks and its interaction to the strong magnetic field generated in non-central heavy-ion collisions. Possible formation of domains of quarks with chirality imbalances is an intrinsic property of the Quantum ChromoDynamics (QCD), which describes the fundamental strong interactions among quarks and gluons. Azimuthal-angle correlations have been used to measure the magnitude of charge- separation across the reaction plane, which was predicted to arise from the CME. However, backgrounds from collective motion (flow) of the collision system can also contribute to the correlation observable. In this poster, we investigate the magnitude of the background utilizing the AMPT model, which contains no CME signals. We demonstrate, for Au +Au collisions at 200 and 39 GeV, a scheme to remove the flow background via the event-shape engineering with the vanishing magnitude of the flow vector. We also calculate the ensemble average of the charge-separation observable, and provide a background baseline for the experimental data.

Proper time regularization and the QCD chiral phase transition

PubMed Central

Cui, Zhu-Fang; Zhang, Jin-Li; Zong, Hong-Shi

2017-01-01

We study the QCD chiral phase transition at finite temperature and finite quark chemical potential within the two flavor Nambu–Jona-Lasinio (NJL) model, where a generalization of the proper-time regularization scheme is motivated and implemented. We find that in the chiral limit the whole transition line in the phase diagram is of second order, whereas for finite quark masses a crossover is observed. Moreover, if we take into account the influence of quark condensate to the coupling strength (which also provides a possible way of how the effective coupling varies with temperature and quark chemical potential), it is found that a CEP may appear. These findings differ substantially from other NJL results which use alternative regularization schemes, some explanation and discussion are given at the end. This indicates that the regularization scheme can have a dramatic impact on the study of the QCD phase transition within the NJL model. PMID:28401889

Broken chiral symmetry on a null plane

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

Beane, Silas R., E-mail: silas@physics.unh.edu

2013-10-15

On a null-plane (light-front), all effects of spontaneous chiral symmetry breaking are contained in the three Hamiltonians (dynamical Poincaré generators), while the vacuum state is a chiral invariant. This property is used to give a general proof of Goldstone’s theorem on a null-plane. Focusing on null-plane QCD with N degenerate flavors of light quarks, the chiral-symmetry breaking Hamiltonians are obtained, and the role of vacuum condensates is clarified. In particular, the null-plane Gell-Mann–Oakes–Renner formula is derived, and a general prescription is given for mapping all chiral-symmetry breaking QCD condensates to chiral-symmetry conserving null-plane QCD condensates. The utility of the null-planemore » description lies in the operator algebra that mixes the null-plane Hamiltonians and the chiral symmetry charges. It is demonstrated that in a certain non-trivial limit, the null-plane operator algebra reduces to the symmetry group SU(2N) of the constituent quark model. -- Highlights: •A proof (the first) of Goldstone’s theorem on a null-plane is given. •The puzzle of chiral-symmetry breaking condensates on a null-plane is solved. •The emergence of spin-flavor symmetries in null-plane QCD is demonstrated.« less

Staggered chiral perturbation theory in the two-flavor case

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

Du Xining

2010-07-01

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

Nucleon Structure Functions from a Chiral Soliton

NASA Astrophysics Data System (ADS)

Weigel, Herbert

1998-10-01

In an attempt to merge the parton model description of deep inelastic scattering with the phenomenologically successful picture of baryons as chiral solitons we study nucleon structure functions in the Nambu--Jona--Lasinio (NJL) chiral soliton model(R. Alkofer, H. Reinhardt and H. Weigel, Phys. Rep. 265) (1996) 139.. We compute the unpolarized structure function for electron--nucleon scattering which enters the Gottfried sum rule, S_G. The model calculation not only explains the observed deviation from the historical value S_G=1/3 but also reproduces the gross features of the exerimental data when accounting for projection and Q^2--evolution(H. Weigel, L. Gamberg and H. Reinhardt, Mod. Phys. Lett. A11) (1996) 3021; Phys. Lett. B399 (1997) 287.. The latter operation further serves to determine the low--momentum scale, Q_0^2, of the model. Subsequently we turn to the polarized structure functions g_1(x,Q^2) and g_2(x,Q^2)(H. Weigel, L. Gamberg and H. Reinhardt, Phys. Rev. D55) (1997) 6910.. These are particularly interesting in the present model because chiral soliton models nicely account for the smallness of the first moment of g_1(x,Q^2). In addition we report on the calculation(L. Gamberg, H. Reinhardt and H. Weigel, Phys. Rev. D58) (1998) 054014. of the chiral odd quark distributions and the corresponding structure functions h_T(x,Q^2) and h_L(x,Q^2). At the low model scale, Q_0^2, we find that the leading twist effective quark distributions, f_1^(q)(x,Q_0^2), g_1^(q)(x,Q_0^2) and h_T^(q)(x,Q_0^2) satisfy Soffer's inequality for both quark flavors q=u,d. The Q^2 evolution of the twist--2 contributions is performed according to the standard GLAP formalism while the twist--three pieces, \\overlineg_2(x) and \\overlineh_L(x), are evolved according to the large NC scheme. Finally we explain the generalization of chiral soliton models to three flavors and discuss the strange quark contribution to g1 as an example(box[t]15cm)O. Schröder, H. Reinhardt and H. Weigel

Chiral dynamics with (non)strange quarks

NASA Astrophysics Data System (ADS)

Kubis, Bastian; Meißner, Ulf-G.

2017-01-01

We review the results and achievements of the project B.3. Topics addressed include pion photoproduction off the proton and off deuterium, three-flavor chiral perturbation theory studies, chiral symmetry tests in Goldstone boson decays, the development of unitarized chiral perturbation theory to next-to-leading order, the two-pole structure of the Λ(1405), the dynamical generation of the lowest S11 resonances, the theory of hadronic atoms and its application to various systems, precision studies in light-meson decays based on dispersion theory, the Roy-Steiner analysis of pion-nucleon scattering, a high-precision extraction of the elusive pion-nucleon σ-term, and aspects of chiral dynamics in few-nucleon systems.

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

NASA Astrophysics Data System (ADS)

Andersen, Jens O.; Kneschke, Patrick

2018-04-01

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

Chiral-symmetry breaking and confinement in Minkowski space

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

Biernat, Elmer P.; Pena, M. T.; Ribiero, J. E.

2016-01-01

We present a model for the quark-antiquark interaction formulated in Minkowski space using the Covariant Spectator Theory. The quark propagators are dressed with the same kernel that describes the interaction between different quarks. By applying the axial-vector Ward-Takahashi identity we show that our model satisfies the Adler-zero constraint imposed by chiral symmetry. For this model, our Minkowski-space results of the dressed quark mass function are compared to lattice QCD data obtained in Euclidean space. The mass function is then used in the calculation of the electromagnetic pion form factor in relativistic impulse approximation, and the results are presented and comparedmore » with the experimental data from JLab.« less

Chiral-symmetry breaking and confinement in Minkowski space

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

Biernat, Elmar P.; Peña, M. T.; Departamento de Física, Instituto Superior Técnico

2016-01-22

We present a model for the quark-antiquark interaction formulated in Minkowski space using the Covariant Spectator Theory. The quark propagators are dressed with the same kernel that describes the interaction between different quarks. By applying the axial-vector Ward-Takahashi identity we show that our model satisfies the Adler-zero constraint imposed by chiral symmetry. For this model, our Minkowski-space results of the dressed quark mass function are compared to lattice QCD data obtained in Euclidean space. The mass function is then used in the calculation of the electromagnetic pion form factor in relativistic impulse approximation, and the results are presented and comparedmore » with the experimental data from JLab.« less

Up quark mass in lattice QCD with three light dynamical quarks and implications for strong CP invariance.

PubMed

Nelson, Daniel R; Fleming, George T; Kilcup, Gregory W

2003-01-17

A standing mystery in the standard model is the unnatural smallness of the strong CP violating phase. A massless up quark has long been proposed as one potential solution. A lattice calculation of the constants of the chiral Lagrangian essential for the determination of the up quark mass, 2alpha(8)-alpha(5), is presented. We find 2alpha(8)-alpha(5)=0.29+/-0.18, which corresponds to m(u)/m(d)=0.410+/-0.036. This is the first such calculation using a physical number of dynamical light quarks, N(f)=3.

Effective chiral restoration in the ρ' meson in lattice QCD

NASA Astrophysics Data System (ADS)

Glozman, L. Ya.; Lang, C. B.; Limmer, Markus

2010-11-01

In simulations with dynamical quarks it has been established that the ground state ρ in the infrared is a strong mixture of the two chiral representations (0,1)+(1,0) and (1/2,1/2)b. Its angular momentum content is approximately the S13 partial wave. Effective chiral restoration in an excited ρ-meson would require that in the infrared this meson couples predominantly to one of the two representations. The variational method allows one to study the mixing of interpolators with different chiral transformation properties in the nonperturbatively determined excited state at different resolution scales. We present results for the first excited state of the ρ-meson using simulations with nf=2 dynamical quarks. We point out, that in the infrared a leading contribution to ρ'=ρ(1450) comes from (1/2,1/2)b, in contrast to the ρ. The ρ' wave function contains a significant contribution of the D13 wave which is not consistent with the quark model prediction.

Chiral symmetry and π - π scattering in the Covariant Spectator Theory

DOE PAGES

Biernat, Elmar P.; Peña, M. T.; Ribeiro, J. E.; ...

2014-11-14

The π-π scattering amplitude calculated with a model for the quark-antiquark interaction in the framework of the Covariant Spectator Theory (CST) is shown to satisfy the Adler zero constraint imposed by chiral symmetry. The CST formalism is established in Minkowski space and our calculations are performed in momentum space. We prove that the axial-vector Ward-Takahashi identity is satisfied by our model. Then we show that, similarly to what happens within the Bethe-Salpeter formalism, application of the axial-vector Ward Takahashi identity to the CST π-π scattering amplitude allows us to sum the intermediate quark-quark interactions to all orders. Thus, the Adlermore » self-consistency zero for π-π scattering in the chiral limit emerges as the result for this sum.« less

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].

Phenomenology of strongly coupled chiral gauge theories

DOE PAGES

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

2016-11-25

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

Partial restoration of chiral symmetry in a confining string

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

Kharzeev, Dmitri E.; Loshaj, F.

2014-08-01

Here, we attempt to describe the interplay of confinement and chiral symmetry breaking in QCD by using the string model. We argue that in the quasi-Abelian picture of confinement based on the condensation of magnetic monopoles and the dual Meissner effect, the world sheet dynamics of the confining string can be effectively described by the 1+1 dimensional massless electrodynamics, which is exactly soluble. The transverse plane distribution of the chromoelectric field stretched between the quark and antiquark sources can then be attributed to the fluctuations in the position of the string. The dependence of the chiral condensate in the stringmore » on the (chromo-)electric field can be evaluated analytically, and is determined by the chiral anomaly and the θ-vacuum structure. Moreover, our picture allows us to predict the distribution of the chiral condensate in the plane transverse to the axis connecting the quark and antiquark. This prediction is compared to the lattice QCD results; a good agreement is found.« less

Chiral symmetry constraints on resonant amplitudes

NASA Astrophysics Data System (ADS)

Bruns, Peter C.; Mai, Maxim

2018-03-01

We discuss the impact of chiral symmetry constraints on the quark-mass dependence of meson resonance pole positions, which are encoded in non-perturbative parametrizations of meson scattering amplitudes. Model-independent conditions on such parametrizations are derived, which are shown to guarantee the correct functional form of the leading quark-mass corrections to the resonance pole positions. Some model amplitudes for ππ scattering, widely used for the determination of ρ and σ resonance properties from results of lattice simulations, are tested explicitly with respect to these conditions.

Kinetics of the chiral phase transition in a linear σ model

NASA Astrophysics Data System (ADS)

Wesp, Christian; van Hees, Hendrik; Meistrenko, Alex; Greiner, Carsten

2018-02-01

We study the dynamics of the chiral phase transition in a linear quark-meson σ model using a novel approach based on semiclassical wave-particle duality. The quarks are treated as test particles in a Monte Carlo simulation of elastic collisions and the coupling to the σ meson, which is treated as a classical field, via a kinetic approach motivated by wave-particle duality. The exchange of energy and momentum between particles and fields is described in terms of appropriate Gaussian wave packets. It has been demonstrated that energy-momentum conservation and the principle of detailed balance are fulfilled, and that the dynamics leads to the correct equilibrium limit. First schematic studies of the dynamics of matter produced in heavy-ion collisions are presented.

Calculation of the hadron contribution from light-by-light scattering to the anomalous (g-2)μ muon magnetic moment for a nonlocal quark model

NASA Astrophysics Data System (ADS)

Zhevlakov, A. S.; Radzhabov, A. E.; Dorokhov, A. E.

2010-11-01

The muon contribution to the anomalous magnetic moment from light-by-light scattering diagrams with pion participation is calculated for a nonlocal chiral quark model. For various nonlocal model parameterizations, the contribution makes a μ Had,LbL = 5.1(0.2) 10-10. Later on, we plan to calculate contributions from diagrams with an intermediate scalar meson and quark boxing.

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

NASA Astrophysics Data System (ADS)

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

2017-08-01

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

Strangeness at high temperatures: from hadrons to quarks.

PubMed

Bazavov, A; Ding, H-T; Hegde, P; Kaczmarek, O; Karsch, F; Laermann, E; Maezawa, Y; Mukherjee, Swagato; Ohno, H; Petreczky, P; Schmidt, C; Sharma, S; Soeldner, W; Wagner, M

2013-08-23

Appropriate combinations of up to fourth order cumulants of net strangeness fluctuations and their correlations with net baryon number and electric charge fluctuations, obtained from lattice QCD calculations, have been used to probe the strangeness carrying degrees of freedom at high temperatures. For temperatures up to the chiral crossover, separate contributions of strange mesons and baryons can be well described by an uncorrelated gas of hadrons. Such a description breaks down in the chiral crossover region, suggesting that the deconfinement of strangeness takes place at the chiral crossover. On the other hand, the strangeness carrying degrees of freedom inside the quark gluon plasma can be described by a weakly interacting gas of quarks only for temperatures larger than twice the chiral crossover temperature. In the intermediate temperature window, these observables show considerably richer structures, indicative of the strongly interacting nature of the quark gluon plasma.

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

DOE PAGES

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

2017-04-12

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

Explicit chiral symmetry breaking in the Nambu-Jona-Lasinio model

NASA Astrophysics Data System (ADS)

Schüren, C.; Arriola, E. Ruiz; Goeke, K.

1992-09-01

We consider a chirally symmetric bosonization of the SU(2) Nambu-Jona-Lasinio model within the Pauli-Villars regularization scheme. Special attention is paid to the way in which chiral symmetry is broken explicitly. The parameters of the model are fixed in the light of chiral perturbation theory by performing a covariant derivative expansion in the presence of external fields. As a by-product we obtain the corresponding low-energy parameters and pion radii as well as some threshold parameters for pion-pion scattering. The nucleon is obtained in terms of the solitonic solutions of the action in the sector with baryon number equal to one. It is found that for a constituent quark mass M ˜ 350 MeV most of the calculated vacuum and pion properties agree reasonably well with the experimental ones and coincide with the region where localized solitons with the right size exist. For this value, however, the scalar and vector pion radii turn out to be very small. A unique determination of the sigma term is proposed, obtaining a value of σ(0) = 41.3 MeV. The scalar nucleon form factor is evaluated in the Breit frame. The extrapolation to the Cheng-Dashen point leads to σ(2 m2) - σ(0) = 7.4 MeV.

Chiral electric separation effect in the quark-gluon plasma

DOE PAGES

Jiang, Yin; Liao, Jinfeng; Huang, Xu-Guang

2015-02-02

In this paper we introduce and compute a new transport coefficient for the quark-gluon plasma (QGP) at very high temperature. This new coefficient σ χe, the CESE (Chiral Electric Separation Effect) conductivity, quantifies the amount of axial current J A that is generated in response to an externally applied electric field eE: J A=σ χe(eE). Starting with a rather general argument in the kinetic theory framework, we show how a characteristic structure σ χe∝μμ5 emerges, which also indicates the CESE as an anomalous transport effect occurring only in a parity-odd environment with nonzero axial charge density μ5 ≠ 0. Usingmore » the Hard-Thermal-Loop framework, the CESE conductivity for the QGP is found to be σ χe = (#)TT rfQ eQ A/g⁴ln(1/g) μμ5/T² to the leading-log accuracy with the numerical constant (#) depending on favor content, e.g., (#)=14.5163 for u, d light flavors.« less

Chiral phase transition at finite chemical potential in 2 +1 -flavor soft-wall anti-de Sitter space QCD

NASA Astrophysics Data System (ADS)

Bartz, Sean P.; Jacobson, Theodore

2018-04-01

The phase transition from hadronic matter to chirally symmetric quark-gluon plasma is expected to be a rapid crossover at zero quark chemical potential (μ ), becoming first order at some finite value of μ , indicating the presence of a critical point. Using a three-flavor soft-wall model of anti-de Sitter/QCD, we investigate the effect of varying the light and strange quark masses on the order of the chiral phase transition. At zero quark chemical potential, we reproduce the Columbia Plot, which summarizes the results of lattice QCD and other holographic models. We then extend this holographic model to examine the effects of finite quark chemical potential. We find that the the chemical potential does not affect the critical line that separates first-order from rapid crossover transitions. This excludes the possibility of a critical point in this model, suggesting that a different setup is necessary to reproduce all the features of the QCD phase diagram.

Chiral Magnetic Effect in Condensed Matters

NASA Astrophysics Data System (ADS)

Li, Qiang

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

Light-quark, heavy-quark systems: An update

NASA Astrophysics Data System (ADS)

Grinstein, B.

1993-06-01

We review many of the recently developed applications of Heavy Quark Effective Theory techniques. After a brief update on Luke's theorem, we describe striking relations between heavy baryon form factors, and how to use them to estimate the accuracy of the extraction of (vert bar)V(sub cb)(vert bar). We discuss factorization and compare with experiment. An elementary presentation, with sample applications, of reparametrization invariance comes next. The final and most extensive chapter in this review deals with phenomenological lagrangians that incorporate heavy-quark spin-flavor as well as light quark chiral symmetries. We compile many interesting results and discuss the validity of the calculations.

Fluctuations in the quark-meson model for QCD with isospin chemical potential

NASA Astrophysics Data System (ADS)

Kamikado, Kazuhiko; Strodthoff, Nils; von Smekal, Lorenz; Wambach, Jochen

2013-01-01

We study the two-flavor quark-meson (QM) model with the functional renormalization group (FRG) to describe the effects of collective mesonic fluctuations on the phase diagram of QCD at finite baryon and isospin chemical potentials, μB and μI. With only isospin chemical potential there is a precise equivalence between the competing dynamics of chiral versus pion condensation and that of collective mesonic and baryonic fluctuations in the quark-meson-diquark model for two-color QCD at finite baryon chemical potential. Here, finite μB = 3 μ introduces an additional dimension to the phase diagram as compared to two-color QCD, however. At zero temperature, the (μI, μ) plane of this phase diagram is strongly constrained by the "Silver Blaze problem." In particular, the onset of pion condensation must occur at μI =mπ / 2, independent of μ as long as μ +μI stays below the constituent quark mass of the QM model or the liquid-gas transition line of nuclear matter in QCD. In order to maintain this relation beyond mean field it is crucial to compute the pion mass from its timelike correlator with the FRG in a consistent way.

How tetraquarks can generate a second chiral phase transition

DOE PAGES

Pisarski, Robert D.; Skokov, Vladimir V.

2016-09-09

We consider how tetraquarks can affect the chiral phase transition in theories like QCD, with light quarks coupled to three colors. For two flavors the tetraquark field is an isosinglet, and its effect is minimal. For three flavors, however, the tetraquark field transforms in the same representation of the chiral symmetry group as the usual chiral order parameter, and so for very light quarks there may be two chiral phase transitions, which are both of first order. In QCD, results from the lattice indicate that any transition from the tetraquark condensate is a smooth crossover. In the plane of temperature,more » T, and quark chemical potential, μ, though, a crossover line for the tetraquark condensate is naturally related to the transition line for color superconductivity. For four flavors we suggest that a triquark field, antisymmetric in both flavor and color, combine to form hexaquarks.« less

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

PubMed

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

2010-09-10

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

Measurement of parity violation in electron–quark scattering

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

Wang, D.; Pan, K.; Subedi, R.

2014-02-05

Symmetry permeates nature and is fundamental to all laws of physics. One example is parity (mirror) symmetry, which implies that flipping left and right does not change the laws of physics. Laws for electromagnetism, gravity and the subatomic strong force respect parity symmetry, but the subatomic weak force does not. Historically, parity violation in electron scattering has been important in establishing (and now testing) the standard model of particle physics. One particular set of quantities accessible through measurements of parity-violating electron scattering are the effective weak couplings C2q, sensitive to the quarks chirality preference when participating in the weak force,more » which have been measured directly3, 4 only once in the past 40?years. Here we report a measurement of the parity-violating asymmetry in electron-quark scattering, which yields a determination of 2C2u???C2d (where u and d denote up and down quarks, respectively) with a precision increased by a factor of five relative to the earlier result. These results provide evidence with greater than 95 per cent confidence that the C2q couplings are non-zero, as predicted by the electroweak theory. They lead to constraints on new parity-violating interactions beyond the standard model, particularly those due to quark chirality. Whereas contemporary particle physics research is focused on high-energy colliders such as the Large Hadron Collider, our results provide specific chirality information on electroweak theory that is difficult to obtain at high energies. Our measurement is relatively free of ambiguity in its interpretation, and opens the door to even more precise measurements in the future.« less

Measurement of parity violation in electron-quark scattering.

PubMed

2014-02-06

Symmetry permeates nature and is fundamental to all laws of physics. One example is parity (mirror) symmetry, which implies that flipping left and right does not change the laws of physics. Laws for electromagnetism, gravity and the subatomic strong force respect parity symmetry, but the subatomic weak force does not. Historically, parity violation in electron scattering has been important in establishing (and now testing) the standard model of particle physics. One particular set of quantities accessible through measurements of parity-violating electron scattering are the effective weak couplings C2q, sensitive to the quarks' chirality preference when participating in the weak force, which have been measured directly only once in the past 40 years. Here we report a measurement of the parity-violating asymmetry in electron-quark scattering, which yields a determination of 2C2u - C2d (where u and d denote up and down quarks, respectively) with a precision increased by a factor of five relative to the earlier result. These results provide evidence with greater than 95 per cent confidence that the C2q couplings are non-zero, as predicted by the electroweak theory. They lead to constraints on new parity-violating interactions beyond the standard model, particularly those due to quark chirality. Whereas contemporary particle physics research is focused on high-energy colliders such as the Large Hadron Collider, our results provide specific chirality information on electroweak theory that is difficult to obtain at high energies. Our measurement is relatively free of ambiguity in its interpretation, and opens the door to even more precise measurements in the future.

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

PubMed

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

2010-03-26

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

Quark-gluon plasma (Selected Topics)

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

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

Introductory lectures to the theory of (strongly interacting) quark-gluon plasma given at the Winter School of Physics of ITEP (Moscow, February 2010). We emphasize theoretical issues highlighted by the discovery of the low viscosity of the plasma. The topics include relativistic hydrodynamics, manifestations of chiral anomaly in hydrodynamics, superfluidity, relativistic superfluid hydrodynamics, effective stringy scalars, holographic models of Yang-Mills theories.

Chiral and deconfinement phase transition in the Hamiltonian approach to QCD in Coulomb gauge

NASA Astrophysics Data System (ADS)

Reinhardt, H.; Vastag, P.

2016-11-01

The chiral and deconfinement phase transitions are investigated within the variational Hamiltonian approach to QCD in Coulomb gauge. The temperature β-1 is introduced by compactifying a spatial dimension. Thereby the whole temperature dependence is encoded in the vacuum state on the spatial manifold R2×S1(β ) . The chiral quark condensate and the dual quark condensate (dressed Polyakov loop) are calculated as a function of the temperature. From their inflection points the pseudocritical temperatures for the chiral and deconfinement crossover transitions are determined. Using the zero-temperature quark and gluon propagators obtained within the variational approach as input, we find 170 and 198 MeV, respectively, for the chiral and deconfinement transition.

Staggered heavy baryon chiral perturbation theory

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

Bailey, Jon A.

2008-03-01

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

Simultaneous Chiral Symmetry Restoration and Deconfinement Consequences for the QCD Phase Diagram

NASA Astrophysics Data System (ADS)

Klähn, Thomas; Fischer, Tobias; Hempel, Matthias

2017-02-01

For studies of quark matter in astrophysical scenarios, the thermodynamic bag model is commonly employed. Although successful, it does not account for dynamical chiral symmetry breaking and repulsions due to the vector interaction which is crucial to explain recent observations of massive, two solar mass neutron stars. In Klähn & Fischer we developed the novel vBag quark matter model which takes these effects into account. This article extends vBag to finite temperatures and isospin asymmetry. Another particular feature of vBag is the determination of the deconfinement bag constant {B}{dc} from a given hadronic equation of state in order to ensure that chiral and deconfinement transitions coincide. We discuss consequences of this novel approach for the phase transition construction, the phase diagram, and implications for protoneutron stars.

Λ hyperon polarization in relativistic heavy ion collisions from a chiral kinetic approach

NASA Astrophysics Data System (ADS)

Sun, Yifeng; Ko, Che Ming

2017-08-01

Using a chiral kinetic approach based on initial conditions from a multiphase transport model, we study the spin polarizations of quarks and antiquarks in noncentral heavy ion collisions at the BNL Relativistic Heavy Ion Collider. Because of the nonvanishing vorticity field in these collisions, quarks and antiquarks are found to acquire appreciable spin polarizations in the direction perpendicular to the reaction plane. Converting quarks and antiquarks to hadrons via the coalescence model, we further calculate the spin polarizations of Λ and anti-Λ hyperons and find their values comparable to those measured in experiments by the STAR Collaboration.

Timoshenko beam model for chiral materials

NASA Astrophysics Data System (ADS)

Ma, T. Y.; Wang, Y. N.; Yuan, L.; Wang, J. S.; Qin, Q. H.

2017-12-01

Natural and artificial chiral materials such as deoxyribonucleic acid (DNA), chromatin fibers, flagellar filaments, chiral nanotubes, and chiral lattice materials widely exist. Due to the chirality of intricately helical or twisted microstructures, such materials hold great promise for use in diverse applications in smart sensors and actuators, force probes in biomedical engineering, structural elements for absorption of microwaves and elastic waves, etc. In this paper, a Timoshenko beam model for chiral materials is developed based on noncentrosymmetric micropolar elasticity theory. The governing equations and boundary conditions for a chiral beam problem are derived using the variational method and Hamilton's principle. The static bending and free vibration problem of a chiral beam are investigated using the proposed model. It is found that chirality can significantly affect the mechanical behavior of beams, making materials more flexible compared with nonchiral counterparts, inducing coupled twisting deformation, relatively larger deflection, and lower natural frequency. This study is helpful not only for understanding the mechanical behavior of chiral materials such as DNA and chromatin fibers and characterizing their mechanical properties, but also for the design of hierarchically structured chiral materials.

Timoshenko beam model for chiral materials

NASA Astrophysics Data System (ADS)

Ma, T. Y.; Wang, Y. N.; Yuan, L.; Wang, J. S.; Qin, Q. H.

2018-06-01

Natural and artificial chiral materials such as deoxyribonucleic acid (DNA), chromatin fibers, flagellar filaments, chiral nanotubes, and chiral lattice materials widely exist. Due to the chirality of intricately helical or twisted microstructures, such materials hold great promise for use in diverse applications in smart sensors and actuators, force probes in biomedical engineering, structural elements for absorption of microwaves and elastic waves, etc. In this paper, a Timoshenko beam model for chiral materials is developed based on noncentrosymmetric micropolar elasticity theory. The governing equations and boundary conditions for a chiral beam problem are derived using the variational method and Hamilton's principle. The static bending and free vibration problem of a chiral beam are investigated using the proposed model. It is found that chirality can significantly affect the mechanical behavior of beams, making materials more flexible compared with nonchiral counterparts, inducing coupled twisting deformation, relatively larger deflection, and lower natural frequency. This study is helpful not only for understanding the mechanical behavior of chiral materials such as DNA and chromatin fibers and characterizing their mechanical properties, but also for the design of hierarchically structured chiral materials.

Measurement of parity violation in electron–quark scattering

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

Wang, D.; Pan, K.; Subedi, R.

2014-02-05

Symmetry permeates nature and is fundamental to all laws of physics. One example is parity (mirror) symmetry, which implies that flipping left and right does not change the laws of physics. Laws for electromagnetism, gravity and the subatomic strong force respect parity symmetry, but the subatomic weak force does not1, 2. Historically, parity violation in electron scattering has been important in establishing (and now testing) the standard model of particle physics. One particular set of quantities accessible through measurements of parity-violating electron scattering are the effective weak couplings C2q, sensitive to the quarks’ chirality preference when participating in the weakmore » force, which have been measured directly3, 4 only once in the past 40 years. Here we report a measurement of the parity-violating asymmetry in electron–quark scattering, which yields a determination of 2C2u-C2d (where u and d denote up and down quarks, respectively) with a precision increased by a factor of five relative to the earlier result. These results provide evidence with greater than 95 per cent confidence that the C2q couplings are non-zero, as predicted by the electroweak theory. They lead to constraints on new parity-violating interactions beyond the standard model, particularly those due to quark chirality. Whereas contemporary particle physics research is focused on high-energy colliders such as the Large Hadron Collider, our results provide specific chirality information on electroweak theory that is difficult to obtain at high energies. Our measurement is relatively free of ambiguity in its interpretation, and opens the door to even more precise measurements in the future.« less

Chiral crossover transition in a finite volume

NASA Astrophysics Data System (ADS)

Shi, Chao; Jia, Wenbao; Sun, An; Zhang, Liping; Zong, Hongshi

2018-02-01

Finite volume effects on the chiral crossover transition of strong interactions at finite temperature are studied by solving the quark gap equation within a cubic volume of finite size L. With the anti-periodic boundary condition, our calculation shows the chiral quark condensate, which characterizes the strength of dynamical chiral symmetry breaking, decreases as L decreases below 2.5 fm. We further study the finite volume effects on the pseudo-transition temperature {T}{{c}} of the crossover, showing a significant decrease in {T}{{c}} as L decreases below 3 fm. Supported by National Natural Science Foundation of China (11475085, 11535005, 11690030, 51405027), the Fundamental Research Funds for the Central Universities (020414380074), China Postdoctoral Science Foundation (2016M591808) and Open Research Foundation of State Key Lab. of Digital Manufacturing Equipment & Technology in Huazhong University of Science & Technology (DMETKF2015015)

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

NASA Astrophysics Data System (ADS)

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

2010-01-01

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

Confined but chirally symmetric hadrons at large density and the Casher's argument

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

Glozman, L. Ya.

2009-08-01

The Casher argument, which is believed to be quite general, states that in the confining regime chiral symmetry is necessarily broken. In the large-N{sub c} limit and at moderate and low temperatures, QCD is confining up to arbitrary large densities, and there should appear a quarkyonic matter. It has been demonstrated, within a manifestly confining and chirally symmetric model, which is a 3+1 dimensional generalization of the 't Hooft model, that, at zero temperature and at a density exceeding a critical one, the chiral symmetry is restored while quarks remain confined in color-singlet hadrons. This is in conflict with themore » Casher argument. Here, we explain the reason why the Casher argument fails and clarify the physical mechanism lying behind such confined but chirally symmetric hadrons.« less

Chiral magnetic effect in condensed matter systems

DOE PAGES

Li, Qiang; Kharzeev, Dmitri E.

2016-12-01

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

Matrix elements of Δ B =0 operators in heavy hadron chiral perturbation theory

NASA Astrophysics Data System (ADS)

Lee, Jong-Wan

2015-05-01

We study the light-quark mass and spatial volume dependence of the matrix elements of Δ B =0 four-quark operators relevant for the determination of Vu b and the lifetime ratios of single-b hadrons. To this end, one-loop diagrams are computed in the framework of heavy hadron chiral perturbation theory with partially quenched formalism for three light-quark flavors in the isospin limit; flavor-connected and -disconnected diagrams are carefully analyzed. These calculations include the leading light-quark flavor and heavy-quark spin symmetry breaking effects in the heavy hadron spectrum. Our results can be used in the chiral extrapolation of lattice calculations of the matrix elements to the physical light-quark masses and to infinite volume. To provide insight on such chiral extrapolation, we evaluate the one-loop contributions to the matrix elements containing external Bd, Bs mesons and Λb baryon in the QCD limit, where sea and valence quark masses become equal. In particular, we find that the matrix elements of the λ3 flavor-octet operators with an external Bd meson receive the contributions solely from connected diagrams in which current lattice techniques are capable of precise determination of the matrix elements. Finite volume effects are at most a few percent for typical lattice sizes and pion masses.

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

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

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

2012-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2018-03-01

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

Kny Coupling Constants and Form Factors from the Chiral Bag Model

NASA Astrophysics Data System (ADS)

Jeong, M. T.; Cheon, Il-T.

2000-09-01

The form factors and coupling constants for KNΛ and KNΣ interactions have been calculated in the framework of the Chiral Bag Model with vector mesons. Taking into account vector meson (ρ, ω, K*) field effects, we find -3.88 ≤ gKNΛ ≤ -3.67 and 1.15 ≤ gKNΣ ≤ 1.24, where the quark-meson coupling constants are determined by fitting the renormalized, πNN coupling constant, [gπNN(0)]2/4π = 14.3. It is shown that vector mesons make significant contributions to the coupling constants gKNΛ and gKNΣ. Our values are existing within the experimental limits compared to the phenomenological values extracted from the kaon photo production experiments.

Chiral symmetry breaking in a semilocalized magnetic field

NASA Astrophysics Data System (ADS)

Cao, Gaoqing

2018-03-01

In this work, we explore the pattern of chiral symmetry breaking and restoration in a solvable magnetic field configuration within the Nambu-Jona-Lasinio model. The special semilocalized static magnetic field can roughly mimic the realistic situation in peripheral heavy ion collisions; thus, the study is important for the dynamical evolution of quark matter. We find that the magnetic-field-dependent contribution from discrete spectra usually dominates over the contribution from continuum spectra and chiral symmetry breaking is locally catalyzed by both the magnitude and scale of the magnetic field. The study is finally extended to the case with finite temperature or chemical potential.

Unexpected manifestation of quark condensation

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

Zinovjev, G. M., E-mail: Gennady.Zinovjev@cern.ch; Molodtsov, S. V.

A comparative analysis of some quark ensembles governed by a four-fermion interaction is performed. Arguments in support of the statement that the presence of a gas-liquid phase transition is a feature peculiar to them are adduced. The instability of small quark droplets is discussed and is attributed to the formation of a chiral soliton. The stability of baryon matter is due to a mixed phase of the vacuum and baryon matter.

Composite Pseudoclassical Models of Quarks

NASA Astrophysics Data System (ADS)

Musin, Yu. R.

2018-05-01

Composite models of quarks are proposed, analogous to composite models of leptons. A model-based explanation of the appearance of generations of fundamental particles in the Standard Model is given. New empirical formulas are proposed for the quark masses, modifying Barut's well-known formula.

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

PubMed

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

2008-11-14

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

Chiral symmetry breaking in QCD with two light flavors.

PubMed

Engel, Georg P; Giusti, Leonardo; Lottini, Stefano; Sommer, Rainer

2015-03-20

A distinctive feature of the presence of spontaneous chiral symmetry breaking in QCD is the condensation of low modes of the Dirac operator near the origin. The rate of condensation must be equal to the slope of M(π)(2)F(π)(2)/2 with respect to the quark mass m in the chiral limit, where M(π) and F(π) are the mass and the decay constant of the Nambu-Goldstone bosons. We compute the spectral density of the (Hermitian) Dirac operator, the quark mass, the pseudoscalar meson mass, and decay constant by numerical simulations of lattice QCD with two light degenerate Wilson quarks. We use lattices generated by the Coordinated Lattice Simulation (CLS) group at three values of the lattice spacing in the range 0.05-0.08 fm, and for several quark masses corresponding to pseudoscalar mesons masses down to 190 MeV. Thanks to this coverage of parameters space, we can extrapolate all quantities to the chiral and continuum limits with confidence. The results show that the low quark modes do condense in the continuum as expected by the Banks-Casher mechanism, and the rate of condensation agrees with the Gell-Mann-Oakes-Renner relation. For the renormalization-group-invariant ratios we obtain [Σ(RGI)](1/3)/F=2.77(2)(4) and Λ(M̅S)/F=3.6(2), which correspond to [Σ(M̅S)(2  GeV)](1/3)=263(3)(4)  MeV and F=85.8(7)(20)  MeV if F(K) is used to set the scale by supplementing the theory with a quenched strange quark.

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

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

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

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

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

DOE PAGES

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

2017-10-10

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

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

NASA Astrophysics Data System (ADS)

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

2017-10-01

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

The Quark's Model and Confinement

ERIC Educational Resources Information Center

Novozhilov, Yuri V.

1977-01-01

Quarks are elementary particles considered to be components of the proton, the neutron, and others. This article presents the quark model as a mathematical concept. Also discussed are gluons and bag models. A bibliography is included. (MA)

Chiral dynamics in the low-temperature phase of QCD

NASA Astrophysics Data System (ADS)

Brandt, Bastian B.; Francis, Anthony; Meyer, Harvey B.; Robaina, Daniel

2014-09-01

We investigate the low-temperature phase of QCD and the crossover region with two light flavors of quarks. The chiral expansion around the point (T,m=0) in the temperature vs quark-mass plane indicates that a sharp real-time excitation exists with the quantum numbers of the pion. An exact sum rule is derived for the thermal modification of the spectral function associated with the axial charge density; the (dominant) pion pole contribution obeys the sum rule. We determine the two parameters of the pion dispersion relation using lattice QCD simulations and test the applicability of the chiral expansion. The time-dependent correlators are also analyzed using the maximum entropy method, yielding consistent results. Finally, we test the predictions of the chiral expansion around the point (T=0,m=0) for the temperature dependence of static observables.

Chiral Dynamics 2006

NASA Astrophysics Data System (ADS)

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

2007-10-01

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

Phenomenology of anomalous chiral transports in heavy-ion collisions

NASA Astrophysics Data System (ADS)

Huang, Xu-Guang

2018-01-01

High-energy Heavy-ion collisions can generate extremely hot quark-gluon matter and also extremely strong magnetic fields and fluid vorticity. Once coupled to chiral anomaly, the magnetic fields and fluid vorticity can induce a variety of novel transport phenomena, including the chiral magnetic effect, chiral vortical effect, etc. Some of them require the environmental violation of parity and thus provide a means to test the possible parity violation in hot strongly interacting matter. We will discuss the underlying mechanism and implications of these anomalous chiral transports in heavy-ion collisions.

Multiple critical endpoints in magnetized three flavor quark matter

NASA Astrophysics Data System (ADS)

Ferreira, Márcio; Costa, Pedro; Providência, Constança

2018-01-01

The magnetized phase diagram for three-flavor quark matter is studied within the Polyakov extended Nambu-Jona-Lasinio model. The order parameters are analyzed with special emphasis on the strange quark condensate. We show that the presence of an external magnetic field induces several critical endpoints (CEPs) in the strange sector, which arise due to the multiple phase transitions that the strange quark undergoes. The spinodal and binodal regions of the phase transitions are shown to increase with external magnetic field strength. The influence of strong magnetic fields on the isentropic trajectories around the several CEPs is analyzed. A focusing effect is observed on the region towards the CEPs that are related with the strange quark phase transitions. Compared to the chiral transitions, the deconfinement transition turns out to be less sensitive to the external magnetic field and the crossover nature is preserved over the whole phase diagram.

Vector-like quarks coupling discrimination at the LHC and future hadron colliders

NASA Astrophysics Data System (ADS)

Barducci, D.; Panizzi, L.

2017-12-01

The existence of new coloured states with spin one-half, i.e. extra-quarks, is a striking prediction of various classes of new physics models. Should one of these states be discovered during the 13 TeV runs of the LHC or at future high energy hadron colliders, understanding its properties will be crucial in order to shed light on the underlying model structure. Depending on the extra-quarks quantum number under SU(2) L , their coupling to Standard Model quarks and bosons have either a dominant left- or right-handed chiral component. By exploiting the polarisation properties of the top quarks arising from the decay of pair-produced extra quarks, we show how it is possible to discriminate among the two hypothesis in the whole discovery range currently accessible at the LHC, thus effectively narrowing down the possible interpretations of a discovered state in terms of new physics scenarios. Moreover, we estimate the discovery and discrimination power of future prototype hadron colliders with centre of mass energies of 33 and 100 TeV.

Chiral Magnetic Effect in Heavy Ion Collisions

DOE PAGES

Liao, Jinfeng

2016-12-01

The Chiral Magnetic Effect (CME) is a remarkable phenomenon that stems from highly nontrivial interplay of QCD chiral symmetry, axial anomaly, and gluonic topology. We show it is of fundamental importance to search for the CME in experiments. The heavy ion collisions provide a unique environment where a hot chiral-symmetric quark-gluon plasma is created, gluonic topological fluctuations generate chirality imbalance, and very strong magnetic fields |Β →|~m 2 π are present during the early stage of such collisions. Significant efforts have been made to look for CME signals in heavy ion collision experiments. Lastly, in this contribution we give amore » brief overview on the status of such efforts.« less

Phase diagram and critical end point for strongly interacting quarks.

PubMed

Qin, Si-xue; Chang, Lei; Chen, Huan; Liu, Yu-xin; Roberts, Craig D

2011-04-29

We introduce a method based on chiral susceptibility, which enables one to draw a phase diagram in the chemical-potential-temperature plane for strongly interacting quarks whose interactions are described by any reasonable gap equation, even if the diagrammatic content of the quark-gluon vertex is unknown. We locate a critical end point at (μ(E),T(E))∼(1.0,0.9)T(c), where T(c) is the critical temperature for chiral-symmetry restoration at μ=0, and find that a domain of phase coexistence opens at the critical end point whose area increases as a confinement length scale grows.

Vectorlike chiral fourth family to explain muon anomalies

NASA Astrophysics Data System (ADS)

Raby, Stuart; Trautner, Andreas

2018-05-01

The Standard Model (SM) is amended by one generation of quarks and leptons which are vectorlike (VL) under the SM gauge group but chiral with respect to a new U(1 ) 3 -4 gauge symmetry. We show that this model can simultaneously explain the deviation of the muon g -2 as well as the observed anomalies in b →s μ+μ- transitions without conflicting with the data on Higgs decays, lepton flavor violation, or Bs-B¯s mixing. The model is string theory motivated and Grand Unified Theory compatible, i.e. UV complete, and fits the data predicting VL quarks, leptons, and a massive Z' at the TeV scale, as well as τ →3 μ and τ →μ γ within reach of future experiments. The Higgs couplings to SM generations are automatically aligned in flavor space.

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.

Effects of the regularization on the restoration of chiral and axial symmetries

NASA Astrophysics Data System (ADS)

Costa, P.; Ruivo, M. C.; de Sousa, C. A.

2008-05-01

The effects of a type of regularization for finite temperatures on the restoration of chiral and axial symmetries are investigated within the SU(3) Nambu-Jona-Lasinio model. The regularization consists in using an infinite cutoff in the integrals that are convergent at finite temperature, a procedure that allows one to take into account the effects of high momentum quarks at high temperatures. It is found that the critical temperature for the phase transition is closer to lattice results than the one obtained with the conventional regularization, and the restoration of chiral and axial symmetries, signaled by the behavior of several observables, occurs simultaneously and at a higher temperature. The restoration of the axial symmetry appears as a natural consequence of the full recovering of the chiral symmetry that was dynamically broken. By using an additional ansatz that simulates instanton suppression effects, by means of a convenient temperature dependence of the anomaly coefficient, we found that the restoration of U(2) symmetry is shifted to lower values, but the dominant effect at high temperatures comes from the new regularization that enhances the decrease of quark condensates, especially in the strange sector.

Quenched results for light quark physics with overlap fermions

NASA Astrophysics Data System (ADS)

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

2002-03-01

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

Light hadron spectra in the constituent quark model with the Kobayashi-Kondo-Maskawa-'t Hooft effective U {sub A} (1) symmetry breaking interaction

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

Dmitrasinovic, V.; Toki, H.; Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047

2006-02-15

We make a critical comparison of several versions of instanton-induced interactions present in the literature, all based on ITEP group's extension to three colours and flavours of 't Hooft's effective lagrangian, with the predictions of the phenomenological Kobayashi-Kondo-Maskawa (KKM) chiral quark lagrangian. We analyze the effects of all versions of the effective U {sub A} (1) symmetry breaking interactions on light hadron spectra in the non-relativistic constituent quark model. We show that the KKMT force, when used as a residual hyperfine interaction reproduces the correct ordering of pseudoscalar and vector mesons even without explicitly taking chiral symmetry into account. Moreover,more » the nucleon spectra are also correctly reproduced, only the Roper resonance remains too high, albeit lower than usual, at 1660 MeV. The latter's lower than expected mass is not due to a small excitation energy, as in the Glozman-Riska (GR) model, but to a combination of colour, flavour, and spatial wave function properties that enhance the relevant matrix elements. The KKMT interaction explicitly depends on flavour and spin of the quarks, but unlike the GR flavour-spin one it has a firm footing in QCD. In the process we provide several technical advances, in particular we show the first explicit derivation of the three-body Fierz transformation and apply it to the KKM interaction. We also discuss the ambiguities associated with the colour degree of freedom.« less

Instanton-dyon ensembles reproduce deconfinement and chiral restoration phase transitions

NASA Astrophysics Data System (ADS)

Shuryak, Edward

2018-03-01

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

Chiral symmetry restoration versus deconfinement in heavy-ion collisions at high baryon density

NASA Astrophysics Data System (ADS)

Cassing, W.; Palmese, A.; Moreau, P.; Bratkovskaya, E. L.

2016-01-01

We study the production of strange hadrons in nucleus-nucleus collisions from 4 to 160 A GeV within the parton-hadron-string dynamics (PHSD) transport approach that is extended to incorporate essentials aspects of chiral symmetry restoration (CSR) in the hadronic sector (via the Schwinger mechanism) on top of the deconfinement phase transition as implemented in PHSD. Especially the K+/π+ and the (Λ +Σ0) /π- ratios in central Au+Au collisions are found to provide information on the relative importance of both transitions. The modeling of chiral symmetry restoration is driven by the pion-nucleon Σ term in the computation of the quark scalar condensate that serves as an order parameter for CSR and also scales approximately with the effective quark masses ms and mq. Furthermore, the nucleon scalar density ρs, which also enters the computation of , is evaluated within the nonlinear σ -ω model which is constrained by Dirac-Brueckner calculations and low-energy heavy-ion reactions. The Schwinger mechanism (for string decay) fixes the ratio of strange to light quark production in the hadronic medium. We find that above ˜80 A GeV the reaction dynamics of heavy nuclei is dominantly driven by partonic degrees of freedom such that traces of the chiral symmetry restoration are hard to identify. Our studies support the conjecture of "quarkyonic matter" in heavy-ion collisions from about 5 to 40 A GeV and provide a microscopic explanation for the maximum in the K+/π+ ratio at about 30 A GeV, which only shows up if a transition to partonic degrees of freedom is incorporated in the reaction dynamics and is discarded in the traditional hadron-string models.

From quarks and gluons to baryon form factors.

PubMed

Eichmann, Gernot

2012-04-01

I briefly summarize recent results for nucleon and [Formula: see text] electromagnetic, axial and transition form factors in the Dyson-Schwinger approach. The calculation of the current diagrams from the quark-gluon level enables a transparent discussion of common features such as: the implications of dynamical chiral symmetry breaking and quark orbital angular momentum, the timelike structure of the form factors, and their interpretation in terms of missing pion-cloud effects.

The Chiral and Angular Momentum Content of the ρ-Meson

NASA Astrophysics Data System (ADS)

Glozman, L. Ya.; Lang, C. B.; Limmer, M.

2010-01-01

It is possible to define and calculate in a gauge-invariant manner the chiral as well as the partial wave content of the quark-antiquark Fock component of a meson in the infrared, where mass is generated. Using the variational method and a set of interpolators that span a complete chiral basis we extract in a lattice QCD Monte Carlo simulation with n f = 2 dynamical light quarks the orbital angular momentum and spin content of the ρ-meson. We obtain in the infrared a simple 3 S 1 component as a leading component of the ρ-meson with a small admixture of the 3 D 1 partial wave, in agreement with the SU(6) flavor-spin symmetry.

The Thomas–Fermi quark model: Non-relativistic aspects

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

Liu, Quan, E-mail: quan_liu@baylor.edu; Wilcox, Walter, E-mail: walter_wilcox@baylor.edu

The first numerical investigation of non-relativistic aspects of the Thomas–Fermi (TF) statistical multi-quark model is given. We begin with a review of the traditional TF model without an explicit spin interaction and find that the spin splittings are too small in this approach. An explicit spin interaction is then introduced which entails the definition of a generalized spin “flavor”. We investigate baryonic states in this approach which can be described with two inequivalent wave functions; such states can however apply to multiple degenerate flavors. We find that the model requires a spatial separation of quark flavors, even if completely degenerate.more » Although the TF model is designed to investigate the possibility of many-quark states, we find surprisingly that it may be used to fit the low energy spectrum of almost all ground state octet and decuplet baryons. The charge radii of such states are determined and compared with lattice calculations and other models. The low energy fit obtained allows us to extrapolate to the six-quark doubly strange H-dibaryon state, flavor symmetric strange states of higher quark content and possible six quark nucleon–nucleon resonances. The emphasis here is on the systematics revealed in this approach. We view our model as a versatile and convenient tool for quickly assessing the characteristics of new, possibly bound, particle states of higher quark number content. -- Highlights: • First application of the statistical Thomas–Fermi quark model to baryonic systems. • Novel aspects: spin as generalized flavor; spatial separation of quark flavor phases. • The model is statistical, but the low energy baryonic spectrum is successfully fit. • Numerical applications include the H-dibaryon, strange states and nucleon resonances. • The statistical point of view does not encourage the idea of bound many-quark baryons.« less

Theoretical model of chirality-induced helical self-propulsion

NASA Astrophysics Data System (ADS)

Yamamoto, Takaki; Sano, Masaki

2018-01-01

We recently reported the experimental realization of a chiral artificial microswimmer exhibiting helical self-propulsion [T. Yamamoto and M. Sano, Soft Matter 13, 3328 (2017), 10.1039/C7SM00337D]. In the experiment, cholesteric liquid crystal (CLC) droplets dispersed in surfactant solutions swam spontaneously, driven by the Marangoni flow, in helical paths whose handedness is determined by the chirality of the component molecules of CLC. To study the mechanism of the emergence of the helical self-propelled motion, we propose a phenomenological model of the self-propelled helical motion of the CLC droplets. Our model is constructed by symmetry argument in chiral systems, and it describes the dynamics of CLC droplets with coupled time-evolution equations in terms of a velocity, an angular velocity, and a tensor variable representing the symmetry of the helical director field of the droplet. We found that helical motions as well as other chiral motions appear in our model. By investigating bifurcation behaviors between each chiral motion, we found that the chiral coupling terms between the velocity and the angular velocity, the structural anisotropy of the CLC droplet, and the nonlinearity of model equations play a crucial role in the emergence of the helical motion of the CLC droplet.

No-Drag Frame for Anomalous Chiral Fluid

DOE PAGES

Stephanov, Mikhail A.; Yee, Ho-Ung

2016-03-24

For an anomalous fluid carrying dissipationless chiral magnetic and/or vortical currents we show that there is a frame in which a stationary obstacle experiences no drag, but energy and charge currents do not vanish, resembling superfluidity. Unlike ordinary superfluid flow, the anomalous chiral currents can transport entropy in this frame. Moreover, we show that the second law of thermodynamics completely determines the amounts of these anomalous nondissipative currents in the “no-drag frame” as polynomials in temperature and chemical potential with known anomaly coefficients. These general results are illustrated and confirmed by a calculation in the chiral kinetic theory and inmore » the quark-gluon plasma at high temperature.« less

Hadronic Lorentz violation in chiral perturbation theory including the coupling to external fields

NASA Astrophysics Data System (ADS)

Kamand, Rasha; Altschul, Brett; Schindler, Matthias R.

2018-05-01

If any violation of Lorentz symmetry exists in the hadron sector, its ultimate origins must lie at the quark level. We continue the analysis of how the theories at these two levels are connected, using chiral perturbation theory. Considering a 2-flavor quark theory, with dimension-4 operators that break Lorentz symmetry, we derive a low-energy theory of pions and nucleons that is invariant under local chiral transformations and includes the coupling to external fields. The pure meson and baryon sectors, as well as the couplings between them and the couplings to external electromagnetic and weak gauge fields, contain forms of Lorentz violation which depend on linear combinations of quark-level coefficients. In particular, at leading order the electromagnetic couplings depend on the very same combinations as appear in the free particle propagators. This means that observations of electromagnetic processes involving hadrons—such as vacuum Cerenkov radiation, which may be allowed in Lorentz-violating theories—can only reliably constrain certain particular combinations of quark coefficients.

Future of Lattice Calculations with Staggered Sea Quarks

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

Gottlieb, Steven

2011-05-23

The MILC collaboration for some years has been creating gauge ensembles with 2+1 flavors of asqtad or improved staggered quarks. There are some 40 ensembles covering a wide range of quark mass and lattice spacing, thus allowing control of the chiral and continuum limits. An extensive review of that program has been published in Reviews of Modern Physics. Recently, MILC has begun a new program using HPQCD's highly improved staggered quark (HISQ) action. This action has smaller taste symmetry breaking than asqtad and improved scaling properties. We also include a dynamical charm quark in these calculations. We summarize the achievementsmore » of the asqtad program, what has been done so far with HISQ quarks, and then consider what future ensembles will be created and their impact.« less

Nuclear chirality, a model and the data

NASA Astrophysics Data System (ADS)

Starosta, K.; Koike, T.

2017-09-01

In the last decade, the manifestation of chirality in atomic nuclei has become the subject of numerous experimental and theoretical studies. The common feature of current model calculations is that the chiral geometry of angular momentum coupling is extracted from expectation values of orientation operators, rather than being a starting point in construction of a model. However, using the particle-hole coupling model for triaxial odd-odd nuclei it is possible to construct a basis which contains right-handed, left-handed and planar states of angular momentum coupling. If this basis is used, the chirality is an explicit rather than an extracted feature as in any other models with non-chiral bases. The time-reversal symmetry, which relates the basis states of opposite handedness, can be used to reduce the dimension of matrices for diagonalization of the model Hamiltonian, proving the effectiveness of this approach. Moreover, the final model eigenstate wave functions show a concentration of amplitudes among a relatively small number (˜1%) of components compared to the full model space. In that sense, the ‘chiral’ basis provides a useful tool to examine model predictions providing direct insight into the structure of doublet states. In this work, similarities and differences between the rotational behaviour of an axial and triaxial body provide a starting point for derivation of the basis optimal for valence nucleon coupling to an axial and a triaxial core. The derived ‘chiral’ basis is optimal for coupling of a valence particle and hole to the triaxial core. Model predictions are presented and discussed. A comprehensive review of current experimental data on observed chiral band candidates is also provided.

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

Strangeness S =-1 hyperon-nucleon interactions: Chiral effective field theory versus lattice QCD

NASA Astrophysics Data System (ADS)

Song, Jing; Li, Kai-Wen; Geng, Li-Sheng

2018-06-01

Hyperon-nucleon interactions serve as basic inputs to studies of hypernuclear physics and dense (neutron) stars. Unfortunately, a precise understanding of these important quantities has lagged far behind that of the nucleon-nucleon interaction due to lack of high-precision experimental data. Historically, hyperon-nucleon interactions are either formulated in quark models or meson exchange models. In recent years, lattice QCD simulations and chiral effective field theory approaches start to offer new insights from first principles. In the present work, we contrast the state-of-the-art lattice QCD simulations with the latest chiral hyperon-nucleon forces and show that the leading order relativistic chiral results can already describe the lattice QCD data reasonably well. Given the fact that the lattice QCD simulations are performed with pion masses ranging from the (almost) physical point to 700 MeV, such studies provide a useful check on both the chiral effective field theory approaches as well as lattice QCD simulations. Nevertheless more precise lattice QCD simulations are eagerly needed to refine our understanding of hyperon-nucleon interactions.

Quark matter symmetry energy and quark stars

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

Chu, Peng-Cheng; Chen, Lie-Wen, E-mail: lwchen@sjtu.edu.cn

2014-01-10

We extend the confined-density-dependent-mass (CDDM) model to include isospin dependence of the equivalent quark mass. Within the confined-isospin-density-dependent-mass (CIDDM) model, we study the quark matter symmetry energy, the stability of strange quark matter, and the properties of quark stars. We find that including isospin dependence of the equivalent quark mass can significantly influence the quark matter symmetry energy as well as the properties of strange quark matter and quark stars. While the recently discovered large mass pulsars PSR J1614–2230 and PSR J0348+0432 with masses around 2 M {sub ☉} cannot be quark stars within the CDDM model, they can bemore » well described by quark stars in the CIDDM model. In particular, our results indicate that the two-flavor u-d quark matter symmetry energy should be at least about twice that of a free quark gas or normal quark matter within the conventional Nambu-Jona-Lasinio model in order to describe PSR J1614–2230 and PSR J0348+0432 as quark stars.« less

Neutrinoless double beta decay and chiral SU(3)

DOE PAGES

Cirigliano, Vincenzo; Dekens, Wouter Gerard; Graesser, Michael Lawrence; ...

2017-04-14

TeV-scale lepton number violation can affect neutrinoless double beta decay through dimension-9 ΔL=ΔI=2 operators involving two electrons and four quarks. Since the dominant effects within a nucleus are expected to arise from pion exchange, the π -→π +ee matrix elements of the dimension-9 operators are a key hadronic input. Here in this letter we provide estimates for the π -→π + matrix elements of all Lorentz scalar ΔI=2 four-quark operators relevant to the study of TeV-scale lepton number violation. The analysis is based on chiral SU(3) symmetry, which relates the π -→π + matrix elements of the ΔI=2 operators to themore » $K$ 0→$$\\bar{K}$$ 0 and K→ππ matrix elements of their ΔS=2 and ΔS=1 chiral partners, for which lattice QCD input is available. The inclusion of next-to-leading order chiral loop corrections to all symmetry relations used in the analysis makes our results robust at the 30% level or better, depending on the operator.« less

Nucleon Spin Structure and Constituent Quark Model

NASA Astrophysics Data System (ADS)

Wang, Fan; Qing, Di; Chen, Xiang-Song; Goldman, T.

1998-10-01

The success of the constituent quark model has been challenged by the nucleon spin structure discovered in polarized deep inelastic scattering (DIS). We find that this puzzle is due to misidentifying the axial charge Δ q and the nonrelativistic quark spin. The space component of the quark axial vector current operator, int d^3x\\overlineψ γγ_5ψ =2s_q, defines the quark spin operator s_q, including not only the Pauli spin operator, which corresponds to the nonrelativistic quark spin s_q^NR, but also relativistic and quark-antiquark pair creation (annihilation) correction terms. Both of these suppress the quark spin contribution for a nucleon at rest due to transverse motion of the quark. The relativistic quark orbital angular momentum operator L_q=int d^3x\\overlineψ x× fracpartial iψ includes L^NRq and two correction terms which are exactly the same as those of sq but of opposite sign. They provide compensation which keeps the total nucleon spin frac 12 untouched no matter what kind of quark model is used. Nucleon spin can be decomposed either as s_q+Lq or as s_q^NR+L_q^NR. (The gluon degree of freedom is assumed to be frozen in the nucleon ground state at low energy scales.) The tensor charge δ q=int d^3x\\overlineψ Σ ψ of the nucleon is predicted to have similar but smaller corrections.

Chiral corrections to the Adler-Weisberger sum rule

NASA Astrophysics Data System (ADS)

Beane, Silas R.; Klco, Natalie

2016-12-01

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

Search for pair production of a new heavy quark that decays into a W boson and a light quark in p p collisions at s = 8 TeV with the ATLAS detector

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2015-12-22

In this study, a search is presented for pair production of a new heavy quark (Q) that decays into a W boson and a light quark (q) in the final state where one W boson decays leptonically (to an electron or muon plus a neutrino) and the other W boson decays hadronically. The analysis is performed using an integrated luminosity of 20.3 fb –1 of pp collisions at √s = 8 TeV collected by the ATLAS detector at the LHC. No evidence of QQ¯ production is observed. New chiral quarks with masses below 690 GeV are excluded at 95% confidencemore » level, assuming BR(Q → Wq)=1. Results are also interpreted in the context of vectorlike quark models, resulting in the limits on the mass of a vectorlike quark in the two-dimensional plane of BR(Q → Wq) versus BR(Q → Hq).« less

Search for pair production of a new heavy quark that decays into a W boson and a light quark in p p collisions at s = 8 TeV with the ATLAS detector

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

Aad, G.; Abbott, B.; Abdallah, J.

2015-12-22

We present a search for pair production of a new heavy quark ( Q ) that decays into a W boson and a light quark (q) in the final state where one W boson decays leptonically (to an electron or muon plus a neutrino) and the other W boson decays hadronically. The analysis is performed using an integrated luminosity of 20.3 fb -1 of pp collisions atmore » $$\\sqrt{s}$$ = 8 TeV collected by the ATLAS detector at the LHC. No evidence of $$Q\\overline{Q}$$ production is observed. New chiral quarks with masses below 690 GeV are excluded at 95% confidence level, assuming BR ( Q → W q ) = 1 . Results are also interpreted in the context of vectorlike quark models, resulting in the limits on the mass of a vectorlike quark in the two-dimensional plane of BR ( Q → W q ) versus BR ( Q → H q ) .« less

Chiral algebras in Landau-Ginzburg models

NASA Astrophysics Data System (ADS)

Dedushenko, Mykola

2018-03-01

Chiral algebras in the cohomology of the {\\overline{Q}}+ supercharge of two-dimensional N=(0,2) theories on flat spacetime are discussed. Using the supercurrent multiplet, we show that the answer is renormalization group invariant for theories with an R-symmetry. For N=(0,2) Landau-Ginzburg models, the chiral algebra is determined by the operator equations of motion, which preserve their classical form, and quantum renormalization of composite operators. We study these theories and then specialize to the N=(2,2) models and consider some examples.

K-->pipi amplitudes from lattice QCD with a light charm quark.

PubMed

Giusti, L; Hernández, P; Laine, M; Pena, C; Wennekers, J; Wittig, H

2007-02-23

We compute the leading-order low-energy constants of the DeltaS=1 effective weak Hamiltonian in the quenched approximation of QCD with up, down, strange, and charm quarks degenerate and light. They are extracted by comparing the predictions of finite-volume chiral perturbation theory with lattice QCD computations of suitable correlation functions carried out with quark masses ranging from a few MeV up to half of the physical strange mass. We observe a DeltaI=1/2 enhancement in this corner of the parameter space of the theory. Although matching with the experimental result is not observed for the DeltaI=1/2 amplitude, our computation suggests large QCD contributions to the physical DeltaI=1/2 rule in the GIM limit, and represents the first step to quantify the role of the charm-quark mass in K-->pipi amplitudes. The use of fermions with an exact chiral symmetry is an essential ingredient in our computation.

Finite volume for three-flavour Partially Quenched Chiral Perturbation Theory through NNLO in the meson sector

NASA Astrophysics Data System (ADS)

Bijnens, Johan; Rössler, Thomas

2015-11-01

We present a calculation of the finite volume corrections to meson masses and decay constants in three flavour Partially Quenched Chiral Perturbation Theory (PQChPT) through two-loop order in the chiral expansion for the flavour-charged (or off-diagonal) pseudoscalar mesons. The analytical results are obtained for three sea quark flavours with one, two or three different masses. We reproduce the known infinite volume results and the finite volume results in the unquenched case. The calculation has been performed using the supersymmetric formulation of PQChPT as well as with a quark flow technique.

Sequential deconfinement of quark flavors in neutron stars

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

Blaschke, D.; Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, RU-141980 Dubna; Sandin, F.

2009-12-15

A scenario is suggested in which the three light quark flavors are sequentially deconfined under increasing pressure in cold asymmetric nuclear matter as found, for example, in neutron stars. The basis for this analysis is a chiral quark matter model of Nambu-Jona-Lasinio (NJL) type with diquark pairing in the spin-1 single-flavor, spin-0 two-flavor, and three-flavor channels. Nucleon dissociation sets in at about the saturation density, n{sub 0}, when the down-quark Fermi sea is populated (d-quark drip line) because of the flavor asymmetry induced by {beta} equilibrium and charge neutrality. At about 3n{sub 0}, u-quarks appear and a two-flavor color superconductingmore » (2SC) phase is formed. The s-quark Fermi sea is populated only at still higher baryon density, when the quark chemical potential is of the order of the dynamically generated strange quark mass. Two different hybrid equations of state (EOSs) are constructed using the Dirac-Brueckner Hartree-Fock (DBHF) approach and the EOS of Shen et al.[H. Shen, H. Toki, K. Oyamatsu, and K. Sumiyoshi, Nucl. Phys. A637, 435 (1998)] in the nuclear matter sector. The corresponding hybrid star sequences have maximum masses of 2.1 and 2.0 M{sub {center_dot}}, respectively. Two- and three-flavor quark-matter phases exist only in gravitationally unstable hybrid star solutions in the DBHF case, whereas the Shen-based EOSs produce stable configurations with a 2SC phase component in the core of massive stars. Nucleon dissociation via d-quark drip could act as a deep crustal heating process, which apparently is required to explain superbursts and cooling of x-ray transients.« less

The Model of Complex Structure of Quark

NASA Astrophysics Data System (ADS)

Liu, Rongwu

2017-09-01

In Quantum Chromodynamics, quark is known as a kind of point-like fundamental particle which carries mass, charge, color, and flavor, strong interaction takes place between quarks by means of exchanging intermediate particles-gluons. An important consequence of this theory is that, strong interaction is a kind of short-range force, and it has the features of ``asymptotic freedom'' and ``quark confinement''. In order to reveal the nature of strong interaction, the ``bag'' model of vacuum and the ``string'' model of string theory were proposed in the context of quantum mechanics, but neither of them can provide a clear interaction mechanism. This article formulates a new mechanism by proposing a model of complex structure of quark, it can be outlined as follows: (1) Quark (as well as electron, etc) is a kind of complex structure, it is composed of fundamental particle (fundamental matter mass and electricity) and fundamental volume field (fundamental matter flavor and color) which exists in the form of limited volume; fundamental particle lies in the center of fundamental volume field, forms the ``nucleus'' of quark. (2) As static electric force, the color field force between quarks has classical form, it is proportional to the square of the color quantity carried by each color field, and inversely proportional to the area of cross section of overlapping color fields which is along force direction, it has the properties of overlap, saturation, non-central, and constant. (3) Any volume field undergoes deformation when interacting with other volume field, the deformation force follows Hooke's law. (4) The phenomena of ``asymptotic freedom'' and ``quark confinement'' are the result of color field force and deformation force.

Hidden charged dark matter and chiral dark radiation

NASA Astrophysics Data System (ADS)

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

2017-10-01

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

Scale-setting, flavor dependence, and chiral symmetry restoration

DOE PAGES

Binosi, D; Roberts, Craig D.; Rodriguez-Quintero, J.

2017-06-13

Here, we determine the flavor dependence of the renormalization-group-invariant running interaction through judicious use of both unquenched Dyson-Schwinger equation and lattice results for QCD’s gauge-sector two-point functions. An important step is the introduction of a physical scale setting procedure that enables a realistic expression of the effect of different numbers of active quark flavours on the interaction. Using this running interaction in concert with a well constrained class of dressed–gluon-quark vertices, we estimate the critical number of active lighter-quarks above which dynamical chiral symmetry breaking becomes impossible: n cr f ≈ 9; and hence in whose neighborhood QCD is plausiblymore » a conformal theory.« less

Chiral susceptibility and the scalar Ward identity.

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

Chang, L.; Liu, Y.-X.; Roberts, C. D.

2009-03-01

The chiral susceptibility is given by the scalar vacuum polarization at zero total momentum. This follows directly from the expression for the vacuum quark condensate so long as a nonperturbative symmetry preserving truncation scheme is employed. For QCD in-vacuum the susceptibility can rigorously be defined via a Pauli-Villars regularization procedure. Owing to the scalar Ward identity, irrespective of the form or Ansatz for the kernel of the gap equation, the consistent scalar vertex at zero total momentum can automatically be obtained and hence the consistent susceptibility. This enables calculation of the chiral susceptibility for markedly different vertex Ansaetze. For themore » two cases considered, the results were consistent and the minor quantitative differences easily understood. The susceptibility can be used to demarcate the domain of coupling strength within a theory upon which chiral symmetry is dynamically broken. Degenerate massless scalar and pseudoscalar bound-states appear at the critical coupling for dynamical chiral symmetry breaking.« less

Chiral susceptibility and the scalar Ward identity

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

Chang Lei; Liu Yuxin; Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000

2009-03-15

The chiral susceptibility is given by the scalar vacuum polarization at zero total momentum. This follows directly from the expression for the vacuum quark condensate so long as a nonperturbative symmetry preserving truncation scheme is employed. For QCD in-vacuum the susceptibility can rigorously be defined via a Pauli-Villars regularization procedure. Owing to the scalar Ward identity, irrespective of the form or Ansatz for the kernel of the gap equation, the consistent scalar vertex at zero total momentum can automatically be obtained and hence the consistent susceptibility. This enables calculation of the chiral susceptibility for markedly different vertex Ansaetze. For themore » two cases considered, the results were consistent and the minor quantitative differences easily understood. The susceptibility can be used to demarcate the domain of coupling strength within a theory upon which chiral symmetry is dynamically broken. Degenerate massless scalar and pseudoscalar bound-states appear at the critical coupling for dynamical chiral symmetry breaking.« less

Simulating Chiral Magnetic and Separation Effects with Spin-Orbit Coupled Atomic Gases

PubMed Central

Huang, Xu-Guang

2016-01-01

The chiral magnetic and chiral separation effects—quantum-anomaly-induced electric current and chiral current along an external magnetic field in parity-odd quark-gluon plasma—have received intense studies in the community of heavy-ion collision physics. We show that analogous effects occur in rotating trapped Fermi gases with Weyl-Zeeman spin-orbit coupling where the rotation plays the role of an external magnetic field. These effects can induce a mass quadrupole in the atomic cloud along the rotation axis which may be tested in future experiments. Our results suggest that the spin-orbit coupled atomic gases are potential simulators of the chiral magnetic and separation effects. PMID:26868084

Nonperturbative quark, gluon, and meson correlators of unquenched QCD

NASA Astrophysics Data System (ADS)

Cyrol, Anton K.; Mitter, Mario; Pawlowski, Jan M.; Strodthoff, Nils

2018-03-01

We present nonperturbative first-principle results for quark, gluon, and meson 1PI correlation functions of two-flavor Landau-gauge QCD in the vacuum. These correlation functions carry the full information about the theory. They are obtained by solving their functional renormalization group equations in a systematic vertex expansion, aiming at apparent convergence. This work represents a crucial prerequisite for quantitative first-principle studies of the QCD phase diagram and the hadron spectrum within this framework. In particular, we have computed the gluon, ghost, quark, and scalar-pseudoscalar meson propagators, as well as gluon, ghost-gluon, quark-gluon, quark, quark-meson, and meson interactions. Our results stress the crucial importance of the quantitatively correct running of different vertices in the semiperturbative regime for describing the phenomena and scales of confinement and spontaneous chiral symmetry breaking without phenomenological input.

Electromagnetic and axial-vector form factors of the quarks and nucleon

NASA Astrophysics Data System (ADS)

Dahiya, Harleen; Randhawa, Monika

2017-11-01

In light of the improved precision of the experimental measurements and enormous theoretical progress, the nucleon form factors have been evaluated with an aim to understand how the static properties and dynamical behavior of nucleons emerge from the theory of strong interactions between quarks. We have analyzed the vector and axial-vector nucleon form factors (GE,Mp,n(Q2) and GAp,n(Q2)) using the spin observables in the chiral constituent quark model (χCQM) which has made a significant contribution to the unraveling of the internal structure of the nucleon in the nonperturbative regime. We have also presented a comprehensive analysis of the flavor decomposition of the form factors (GEq(Q2), GMq(Q2) and GAq(Q2) for q = u,d,s) within the framework of χCQM with emphasis on the extraction of the strangeness form factors which are fundamental to determine the spin structure and test the chiral symmetry breaking effects in the nucleon. The Q2 dependence of the vector and axial-vector form factors of the nucleon has been studied using the conventional dipole form of parametrization. The results are in agreement with the available experimental data.

Relations between heavy-light meson and quark masses

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

Relations between heavy-light meson and quark masses

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

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

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

Relations between heavy-light meson and quark masses

DOE PAGES

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

2018-02-07

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

Chiral effective theory of dark matter direct detection

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

Bishara, Fady; Brod, Joachim; Grinstein, Benjamin

2017-02-01

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

Spin-flavor structure of chiral-odd generalized parton distributions in the large- N c limit

DOE PAGES

Schweitzer, P.; Weiss, C.

2016-10-05

We study the spin-flavor structure of the nucleon's chiral-odd generalized parton distributions (transversity GPDs) in the large-N c limit of QCD. In contrast to the chiral-even case, only three combinations of the four chiral-odd GPDs are nonzero in the leading order of the 1/N c expansion: E-bar T = E T+2H-tilde T, H T, and E-tilde T. The degeneracy is explained by the absence of spin-orbit interactions correlating the transverse momentum transfer with the transverse quark spin. It can also be deduced from the natural N c scaling of the quark-nucleon helicity amplitudes associated with the GPDs. In the GPDmore » E-bar T the flavor-singlet component u+d is leading in the 1/N c expansion, while in H T and E-tilde T it is the flavor-nonsinglet components u–d. Furthermore, the large-N c relations are consistent with the spin-flavor structure extracted from hard exclusive π 0 and η electroproduction data, if it is assumed that the processes are mediated by twist-3 amplitudes involving the chiral-odd GPDs and the chiral-odd pseudoscalar meson distribution amplitudes.« less

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

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

Bar-Shalom, Shaouly; Soni, Amarjit

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

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

DOE PAGES

Bar-Shalom, Shaouly; Soni, Amarjit

2017-03-10

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

The topological susceptibility from grand canonical simulations in the interacting instanton liquid model: Chiral phase transition and axion mass

NASA Astrophysics Data System (ADS)

Wantz, Olivier; Shellard, E. P. S.

2010-04-01

This is the last in a series of papers on the topological susceptibility in the interacting instanton liquid model (IILM). We will derive improved finite temperature interactions to study the thermodynamic limit of grand canonical Monte Carlo simulations in the quenched and unquenched case with light, physical quark masses. In particular, we will be interested in chiral symmetry breaking. The paper culminates by giving, for the first time, a well-motivated temperature-dependent axion mass. Especially, this work finally provides a computation of the axion mass in the low temperature regime, ma2fa2=1.46×10-3Λ41+0.50 T/Λ1+(3.53 . It connects smoothly to the high temperature dilute gas approximation; the latter is improved by including quark threshold effects. To compare with earlier studies, we also provide the usual power-law ma2=αΛ4fa2(T, where Λ=400 MeV, n=6.68 and α=1.68×10-7.

Checker Board Model predicts 5 Generations of Quarks

NASA Astrophysics Data System (ADS)

Lach, Theodore M., II

2002-10-01

The Checker Board Model (CBM) of the nucleus is a 2 Dimensional model that relies on the belief that nature is superbly symmetric and the belief that the synchronization of the 2 outer rotating quarks in the nucleons accounts for magnetic moment of the nucleons and that the magnetic flux from the nucleons couples (weaves) into the checker board array structures and this in addition to electrostatic forces of the rotating and stationary quarks accounts for the apparent strong nuclear force. The symmetry of the He nucleus, one might call it Super Symmetric, helps explain the stable structure of the alpha particle. A semi-classical (relativistic) approach was used to explain the mass of the proton and neutron, along with their magnetic moments and their absolute and relative sizes in terms of the above structure and two newly proposed quarks (1) : the "up" and the "dn" quarks, not to be confused with the lighter u and d quarks in the standard model. Using the prescribed 2D checkerboard arrays where protons go on dark squares and neutrons go on light squares, one is able to recreate all the known nuclei. This exercise came up with structures that could explain the rational for the Halo nuclei and why 9He was so unstable where as 8He was much more stable and 10He is not a bound structure. Since the heavy masses of the "up" and "dn" quark (237.31 MeV and 42.392 MeV respectively) did not fit within the standard model as candidates for u and d, a new model (New Physics) had to be invented that would explain why "up" and "dn" were so heavy. Trial and error resulted in the empirical fitting of these two new quarks into a scheme that placed them between the mass of u / d and the c / s quarks. This new particle physics model predicts that nature has 5 generations not 3. Perhaps it should be called the 5G model. The two new generations come from the "up" and "dn' quark and a much heavier generation of a 42.5 GeV "massive dn" or (Big Bottom, B') and 65 GeV "massive up" or (Big

A quark model analysis of the transversity distribution

NASA Astrophysics Data System (ADS)

Scopetta, Sergio; Vento, Vicente

1998-04-01

The feasibility of measuring chiral-odd parton distribution functions in polarized Drell-Yan and semi-inclusive experiments has renewed theoretical interest in their study. Models of hadron structure have proven successful in describing the gross features of the chiral-even structure functions. Similar expectations motivated our study of the transversity parton distributions in the Isgur-Karl and MIT bag models. We confirm, by performing a NLO calculation, the diverse low x behaviors of the transversity and spin structure functions at the experimental scale and show that it is fundamentally a consequence of the different behaviors under evolution of these functions. The inequalities of Soffer establish constraints between data and model calculations of the chiral-odd transversity function. The approximate compatibility of our model calculations with these constraints confers credibility to our estimates.

Maxwell-Chern-Simons hydrodynamics for the chiral magnetic effect

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

Oezoender, Sener

2010-06-15

The rate of vacuum-changing topological solutions of the gluon field, sphalerons, is estimated to be large at the typical temperatures of heavy-ion collisions, particularly at the Relativistic Heavy Ion Collider. Such windings in the gluon field are expected to produce parity-odd bubbles, which cause separation of positively and negatively charged quarks along the axis of the external magnetic field. This chiral magnetic effect can be mimicked by Chern-Simons modified electromagnetism. Here we present a model of relativistic hydrodynamics including the effects of axial anomalies via the Chern-Simons term.

Quark Model in the Quantum Mechanics Curriculum.

ERIC Educational Resources Information Center

Hussar, P. E.; And Others

1980-01-01

This article discusses in detail the totally symmetric three-quark karyonic wave functions. The two-body mesonic states are also discussed. A brief review of the experimental efforts to identify the quark model multiplets is given. (Author/SK)

Is nucleon spin structure inconsistent with the constituent quark model?

NASA Astrophysics Data System (ADS)

Qing, Di; Chen, Xiang-Song; Wang, Fan

1998-12-01

Proton spin structure discovered in polarized deep inelastic scattering is shown to be consistent with the valence-sea quark mixing constituent quark model. The relativistic correction and quark-antiquark pair creation (annihilation) terms inherently involved in the quark axial vector current suppress the quark spin contribution to the proton spin. The relativistic quark orbital angular momentum provides compensative terms to keep the proton spin 12 untouched. The tensor charge of the proton is predicted to have a similar but smaller suppression. An explanation on why baryon magnetic moments can be parametrized by the naive quark model spin content as well as the spin structure discovered in polarized deep inelastic scattering is given.

Nucleon properties in the Polyakov quark-meson model

NASA Astrophysics Data System (ADS)

Li, Yingying; Hu, Jinniu; Mao, Hong

2018-05-01

We study the nucleon as a nontopological soliton in a quark medium as well as in a nucleon medium in terms of the Polyakov quark-meson (PQM) model with two flavors at finite temperature and density. The constituent quark masses evolving with the temperature at various baryon chemical potentials are calculated and the equations of motion are solved according to the proper boundary conditions. The PQM model predicts an increasing size of the nucleon and a reduction of the nucleon mass in both hot environment. However, the phase structure is different from each other in quark and nucleon mediums. There is a crossover in the low-density region and a first-order phase transition in the high-density region in quark medium, whereas there exists a crossover characterized by the overlap of the nucleons in nucleon medium.

Three flavor Nambu-Jona-Lasinio model with Polyakov loop and competition with nuclear matter

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

Ciminale, M.; Ippolito, N. D.; Nardulli, G.

2008-03-01

We study the phase diagram of the three flavor Polyakov-Nambu-Jona-Lasinio (PNJL) model and, in particular, the interplay between chiral symmetry restoration and deconfinement crossover. We compute chiral condensates, quark densities, and the Polyakov loop at several values of temperature and chemical potential. Moreover we investigate on the role of the Polyakov loop dynamics in the transition from nuclear matter to quark matter.

Strange quark condensate in the nucleon in 2 + 1 flavor QCD.

PubMed

Toussaint, D; Freeman, W

2009-09-18

We calculate the "strange quark content of the nucleon," , which is important for interpreting the results of some dark matter detection experiments. The method is to evaluate quark-line disconnected correlations on the MILC lattice ensembles, which include the effects of dynamical light and strange quarks. After continuum and chiral extrapolations, the result is = 0.69(7)_{stat}(9)_{syst}, in the modified minimal subtraction scheme (2 GeV) regularization, or for the renormalization scheme invariant form, m_{s} partial differentialM_{N}/ partial differentialm_{s} = 59(6)(8) MeV.

Vector mesons in the Nambu-Jona-Lasinio model

NASA Astrophysics Data System (ADS)

Schüren, C.; Döring, F.; Ruiz Arriola, E.; Goeke, K.

1993-12-01

We investigate solitonic solutions with baryon number equal to one of the semi-bosonized SU(2) Nambu-Jona-Lasinio model including σ -, π -, ρ -, A 1- and ω-mesons both on the chiral circle ( σ2r) + π2( r) = f2π) and beyond it ( σ2( r) + π2( r) ≠ f2π). The action is treated in the mesonic and baryonic sector in the leading order of the large- Nc expansion (one-quark-loop approximation). The UV-divergent real part of the effective action is rendered finite using different gauge-invariant regularization methods (Pauli-Villars and proper time). The parameters of the model are fixed in two different ways: either approximately by a heat kernel expansion of the effective action up to second order or by an exact calculation of the mesonic on-shell masses. This leaves the constituent quark mass as the only free parameter of the model. In the solitonic sector we pay special attention to the way the Wick rotation from euclidean space back to Minkowski space has to be performed. We get solitonic solutions from hedgehoglike field configurations on the chiral circle for a wide range of couplings. We also find that if the chiral-circle constraint is relaxed vector mesons provide stable solitonic solutions. Moreover, whether the baryon number is carried by the valence quarks or by the Dirac sea depends strongly on the particular values of the constituent quark mass. We also study the low-energy limit of the model and its connection to chiral perturbation theory. To this end a covariant-derivative expansion is performed in the presence of external fields. After integrating out the scalar, vector and axial degrees of freedom this leads to the corresponding low-energy parameters as e.g. pion radii and some threshold parameters for pion-pion scattering. Vector mesons provide a natural explanation for an axial coupling constant at the quark level gAQ lower than one. However, we find for the gAN of the nucleon noticeable deviations from the non-relativistic quark model

Index theorem and universality properties of the low-lying eigenvalues of improved staggered quarks.

PubMed

Follana, E; Hart, A; Davies, C T H

2004-12-10

We study various improved staggered quark Dirac operators on quenched gluon backgrounds in lattice QCD generated using a Symanzik-improved gluon action. We find a clear separation of the spectrum into would-be zero modes and others. The number of would-be zero modes depends on the topological charge as expected from the index theorem, and their chirality expectation value is large ( approximately 0.7). The remaining modes have low chirality and show clear signs of clustering into quartets and approaching the random matrix theory predictions for all topological charge sectors. We conclude that improvement of the fermionic and gauge actions moves the staggered quarks closer to the continuum limit where they respond correctly to QCD topology.

Implications of heavy quark-diquark symmetry for excited doubly heavy baryons and tetraquarks

NASA Astrophysics Data System (ADS)

Mehen, Thomas

2017-11-01

We give heavy quark-diquark symmetry predictions for doubly heavy baryons and tetraquarks in light of the recent discovery of the Ξcc ++ by LHCb. For five excited doubly charm baryons that are predicted to lie below the ΛcD threshold, we give predictions for their electromagnetic and strong decays using a previously developed chiral Lagrangian with heavy quark-diquark symmetry. Based on the mass of the Ξcc ++, the existence of a doubly heavy bottom I =0 tetraquark that is stable to strong and electromagnetic decays has been predicted. If the mass of this state is below 10405 MeV, as predicted in some models, we argue using heavy quark-diquark symmetry that the JP=1+ I =1 doubly bottom tetraquark state will lie just below the open bottom threshold and likely be a narrow state as well. In this scenario, we compute strong decay width for this state using a new Lagrangian for doubly heavy tetraquarks which is related to the singly heavy baryon Lagrangian by heavy quark-diquark symmetry.

Chiral symmetry breaking and the spin content of hadrons

NASA Astrophysics Data System (ADS)

Glozman, L. Ya.; Lang, C. B.; Limmer, M.

2012-04-01

From the parton distributions in the infinite momentum frame, one finds that only about 30% of the nucleon spin is carried by spins of the valence quarks, which gave rise to the term “spin crisis”. Similar results hold for the lowest mesons, as it follows from the lattice simulations. We define the spin content of a meson in the rest frame and use a complete and orthogonal q¯q chiral basis and a unitary transformation from the chiral basis to the 2LJ basis. Then, given a mixture of different allowed chiral representations in the meson wave function at a given resolution scale, one can obtain its spin content at this scale. To obtain the mixture of the chiral representations in the meson, we measure in dynamical lattice simulations a ratio of couplings of interpolators with different chiral structure. For the ρ meson, we obtain practically the 3S1 state with no trace of the spin crisis. Then a natural question arises: which definition does reflect the spin content of a hadron?

Application of classical models of chirality to optical rectification

NASA Astrophysics Data System (ADS)

Wang, Xiao-Ou; Gong, Li-Jing; Li, Chun-Fei

2008-08-01

Classical models of chirality are used to investigate the optical rectification effect in chiral molecular media. Calculation of the zero frequency first hyperpolarizabilities of chiral molecules with different structures is performed and applied to the derivation of a dc electric-dipole polarization. The expression of second-order nonlinear static-electric-dipole susceptibilities is obtained by theoretical derivation in the isotropic chiral thin films. The microscopic mechanism producing optical rectification is analyzed in view of this calculation. We find that optical rectification is derived from interaction between the electric field gradient (spatial dispersion) and chiral molecules in optically active liquids and solution by our calculation, which is consistent with the result given by Woźniak and Wagnière [Opt. Commun. 114, 131 (1995)]: The optical rectification depends on the fourth-order electric-dipole susceptibilities.

Euclidean bridge to the relativistic constituent quark model

NASA Astrophysics Data System (ADS)

Hobbs, T. J.; Alberg, Mary; Miller, Gerald A.

2017-03-01

Background: Knowledge of nucleon structure is today ever more of a precision science, with heightened theoretical and experimental activity expected in coming years. At the same time, a persistent gap lingers between theoretical approaches grounded in Euclidean methods (e.g., lattice QCD, Dyson-Schwinger equations [DSEs]) as opposed to traditional Minkowski field theories (such as light-front constituent quark models). Purpose: Seeking to bridge these complementary world views, we explore the potential of a Euclidean constituent quark model (ECQM). This formalism enables us to study the gluonic dressing of the quark-level axial-vector vertex, which we undertake as a test of the framework. Method: To access its indispensable elements with a minimum of inessential detail, we develop our ECQM using the simplified quark + scalar diquark picture of the nucleon. We construct a hyperspherical formalism involving polynomial expansions of diquark propagators to marry our ECQM with the results of Bethe-Salpeter equation (BSE) analyses, and constrain model parameters by fitting electromagnetic form factor data. Results: From this formalism, we define and compute a new quantity—the Euclidean density function (EDF)—an object that characterizes the nucleon's various charge distributions as functions of the quark's Euclidean momentum. Applying this technology and incorporating information from BSE analyses, we find the quenched dressing effect on the proton's axial-singlet charge to be small in magnitude and consistent with zero, while use of recent determinations of unquenched BSEs results in a large suppression. Conclusions: The quark + scalar diquark ECQM is a step toward a realistic quark model in Euclidean space, and needs additional refinements. The substantial effect we obtain for the impact on the axial-singlet charge of the unquenched dressed vertex compared to the quenched demands further investigation.

Exotic quarks in Twin Higgs models

DOE PAGES

Cheng, Hsin -Chia; Jung, Sunghoon; Salvioni, Ennio; ...

2016-03-14

The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ~ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of themore » model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles with long lifetimes, giving spectacular displaced vertex signals in combination with the prompt top quarks. This happens in the Fraternal Twin Higgs scenario with typical parameters, and sometimes is even necessary for cosmological reasons. We study the potential displaced vertex signals from the decays of the twin bottomonia, twin glueballs, and twin leptons in the Fraternal Twin Higgs scenario. As a result, depending on the details of the twin sector, the exotic quarks may be probed up to ~ 2.5 TeV at the LHC and beyond 10 TeV at a future 100 TeV collider, providing a strong test of this class of ultraviolet completions.« less

Chiral helimagnetic state in a Kondo lattice model with the Dzyaloshinskii-Moriya interaction

NASA Astrophysics Data System (ADS)

Okumura, Shun; Kato, Yasuyuki; Motome, Yukitoshi

2018-05-01

Monoaxial chiral magnets can form a noncollinear twisted spin structure called the chiral helimagnetic state. We study magnetic properties of such a chiral helimagnetic state, with emphasis on the effect of itinerant electrons. Modeling a monoaxial chiral helimagnet by a one-dimensional Kondo lattice model with the Dzyaloshinskii-Moriya interaction, we perform a variational calculation to elucidate the stable spin configuration in the ground state. We obtain a chiral helimagnetic state as a candidate for the ground state, whose helical pitch is modulated by the model parameters: the Kondo coupling, the Dzyaloshinski-Moriya interaction, and electron filling.

Transverse-momentum-dependent quark distribution functions of spin-one targets: Formalism and covariant calculations

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

Ninomiya, Yu; Bentz, Wolfgang; Cloet, Ian C.

In this paper, we present a covariant formulation and model calculations of the leading-twist time-reversal even transverse-momentum-dependent quark distribution functions (TMDs) for a spin-one target. Emphasis is placed on a description of these three-dimensional distribution functions which is independent of any constraints on the spin quantization axis. We apply our covariant spin description to all nine leading-twist time-reversal even ρ meson TMDs in the framework provided by the Nambu–Jona-Lasinio model, incorporating important aspects of quark confinement via the infrared cutoff in the proper-time regularization scheme. In particular, the behaviors of the three-dimensional TMDs in a tensor polarized spin-one hadron aremore » illustrated. Sum rules and positivity constraints are discussed in detail. Our results do not exhibit the familiar Gaussian behavior in the transverse momentum, and other results of interest include the finding that the tensor polarized TMDs—associated with spin-one hadrons—are very sensitive to quark orbital angular momentum, and that the TMDs associated with the quark operator γ +γ Tγ 5 would vanish were it not for dynamical chiral symmetry breaking. In addition, we find that 44% of the ρ meson's spin is carried by the orbital angular momentum of the quarks, and that the magnitude of the tensor polarized quark distribution function is about 30% of the unpolarized quark distribution. Finally, a qualitative comparison between our results for the tensor structure of a quark-antiquark bound state is made to existing experimental and theoretical results for the two-nucleon (deuteron) bound state.« less

Transverse-momentum-dependent quark distribution functions of spin-one targets: Formalism and covariant calculations

DOE PAGES

Ninomiya, Yu; Bentz, Wolfgang; Cloet, Ian C.

2017-10-24

In this paper, we present a covariant formulation and model calculations of the leading-twist time-reversal even transverse-momentum-dependent quark distribution functions (TMDs) for a spin-one target. Emphasis is placed on a description of these three-dimensional distribution functions which is independent of any constraints on the spin quantization axis. We apply our covariant spin description to all nine leading-twist time-reversal even ρ meson TMDs in the framework provided by the Nambu–Jona-Lasinio model, incorporating important aspects of quark confinement via the infrared cutoff in the proper-time regularization scheme. In particular, the behaviors of the three-dimensional TMDs in a tensor polarized spin-one hadron aremore » illustrated. Sum rules and positivity constraints are discussed in detail. Our results do not exhibit the familiar Gaussian behavior in the transverse momentum, and other results of interest include the finding that the tensor polarized TMDs—associated with spin-one hadrons—are very sensitive to quark orbital angular momentum, and that the TMDs associated with the quark operator γ +γ Tγ 5 would vanish were it not for dynamical chiral symmetry breaking. In addition, we find that 44% of the ρ meson's spin is carried by the orbital angular momentum of the quarks, and that the magnitude of the tensor polarized quark distribution function is about 30% of the unpolarized quark distribution. Finally, a qualitative comparison between our results for the tensor structure of a quark-antiquark bound state is made to existing experimental and theoretical results for the two-nucleon (deuteron) bound state.« less

A quark model analysis of orbital angular momentum

NASA Astrophysics Data System (ADS)

Scopetta, Sergio; Vento, Vicente

1999-08-01

Orbital Angular Momentum (OAM) twist-two parton distributions are studied. At the low energy, hadronic, scale we calculate them for the relativistic MIT bag model and for non-relativistic potential quark models. We reach the scale of the data by leading order evolution using the OPE and perturbative QCD. We confirm that the contribution of quarks and gluons OAM to the nucleon spin grows with Q2, and it can be relevant at the experimental scale, even if it is negligible at the hadronic scale, irrespective of the model used. The sign and shape of the quark OAM distribution at high Q2 may depend strongly on the relative size of the OAM and spin distributions at the hadronic scale. Sizeable quark OAM distributions at the hadronic scale, as proposed by several authors, can produce the dominant contribution to the nucleon spin at high Q2. As expected by general arguments, we obtain, that the large gluon OAM contribution is almost cancelled by the gluon spin contribution.

Flavor structure of Λ baryons from lattice QCD: From strange to charm quarks

NASA Astrophysics Data System (ADS)

Gubler, Philipp; Takahashi, Toru T.; Oka, Makoto

2016-12-01

We study Λ baryons of spin-parity 1/2± with either a strange or charm valence quark in full 2 +1 flavor lattice QCD. Multiple S U (3 ) singlet and octet operators are employed to generate the desired single baryon states on the lattice. Via the variational method, the couplings of these states to the different operators provide information about the flavor structure of the Λ baryons. We make use of the gauge configurations of the PACS-CS Collaboration and chirally extrapolate the results for the masses and S U (3 ) flavor components to the physical point. We furthermore gradually change the hopping parameter of the heaviest quark from strange to charm to study how the properties of the Λ baryons evolve as a function of the heavy quark mass. It is found that the baryon energy levels increase almost linearly with the quark mass. Meanwhile, the flavor structure of most of the states remains stable, with the exception of the lowest 1/2- state, which changes from a flavor singlet Λ to a Λc state with singlet and octet components of comparable size. Finally, we discuss whether our findings can be interpreted with the help of a simple quark model and find that the negative-parity Λc states can be naturally explained as diquark excitations of the light u and d quarks. On the other hand, the quark-model picture does not appear to be adequate for the negative-parity Λ states, suggesting the importance of other degrees of freedom to describe them.

Topology in the SU(Nf) chiral symmetry restored phase of unquenched QCD and axion cosmology

NASA Astrophysics Data System (ADS)

Azcoiti, Vicente

2018-03-01

The axion is one of the more interesting candidates to make the dark matter of the universe, and the axion potential plays a fundamental role in the determination of the dynamics of the axion field. Moreover, the way in which the U(1)A anomaly manifests itself in the chiral symmetry restored phase of QCD at high temperature could be tested when probing the QCD phase transition in relativistic heavy ion collisions. With these motivations, we investigate the physical consequences of the survival of the effects of the U(1)A anomaly in the chiral symmetric phase of QCD, and show that the free energy density is a singular function of the quark mass m, in the chiral limit, and that the σ and π susceptibilities diverge in this limit at any T ≥ Tc. We also show that the difference between the π and t;δ susceptibilities diverges in the chiral limit at any T ≥ Tc, a result that can be contrasted with the existing lattice calculations; and discuss on the generalization of these results to the Nf ≥ 3 model.

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

DOE PAGES

Müller, Niklas; Schlichting, Sören; Sharma, Sayantan

2016-09-30

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

Chiral symmetry breaking and the spin content of the ρ and ρ‧ mesons

NASA Astrophysics Data System (ADS)

Glozman, L. Ya.; Lang, C. B.; Limmer, M.

2011-11-01

Using interpolators with different SU(2)L × SU(2)R transformation properties we study the chiral symmetry and spin contents of the ρ and ρ‧ mesons in lattice simulations with dynamical quarks. A ratio of couplings of the qbarγi τq and qbarσ0i τq interpolators to a given meson state at different resolution scales tells one about the degree of chiral symmetry breaking in the meson wave function at these scales. Using a Gaussian gauge invariant smearing of the quark fields in the interpolators, we are able to extract the chiral content of mesons up to the infrared resolution of ∼ 1 fm. In the ground state ρ meson the chiral symmetry is strongly broken with comparable contributions of both the (0 , 1) + (1 , 0) and (1 / 2 , 1 / 2) b chiral representations with the former being the leading contribution. In contrast, in the ρ‧ meson the degree of chiral symmetry breaking is manifestly smaller and the leading representation is (1 / 2 , 1 / 2) b. Using a unitary transformation from the chiral basis to the LJ2S+1 basis, we are able to define and measure the angular momentum content of mesons in the rest frame. This definition is different from the traditional one which uses parton distributions in the infinite momentum frame. The ρ meson is practically a 3S1 state with no obvious trace of a "spin crisis". The ρ‧ meson has a sizeable contribution of the 3D1 wave, which implies that the ρ‧ meson cannot be considered as a pure radial excitation of the ρ meson.

QCD equation of state with almost physical quark masses

NASA Astrophysics Data System (ADS)

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

2008-01-01

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

From quarks to nucleons in dark matter direct detection

NASA Astrophysics Data System (ADS)

Bishara, Fady; Brod, Joachim; Grinstein, Benjamin; Zupan, Jure

2017-11-01

We provide expressions for the nonperturbative matching of the effective field theory describing dark matter interactions with quarks and gluons to the effective theory of nonrelativistic dark matter interacting with nonrelativistic nucleons. We give expressions of leading and subleading order in chiral counting. In general, a single partonic operator matches onto several nonrelativistic operators already at leading order in chiral counting. Keeping only one operator at the time in the nonrelativistic effective theory thus does not properly describe the scattering in direct detection. The matching of the axial-axial partonic level operator, as well as the matching of the operators coupling DM to the QCD anomaly term, include naively momentum suppressed terms. However, these are still of leading chiral order due to pion poles and can be numerically important.

Chiral Gold Nanoclusters: Atomic Level Origins of Chirality.

PubMed

Zeng, Chenjie; Jin, Rongchao

2017-08-04

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

Dissipative vibrational model for chiral recognition in olfaction

NASA Astrophysics Data System (ADS)

Tirandaz, Arash; Taher Ghahramani, Farhad; Shafiee, Afshin

2015-09-01

We examine the olfactory discrimination of left- and right-handed enantiomers of chiral odorants based on the odorant-mediated electron transport from a donor to an acceptor of the olfactory receptors embodied in a biological environment. The chiral odorant is effectively described by an asymmetric double-well potential whose minima are associated to the left- and right-handed enantiomers. The introduced asymmetry is considered an overall measure of chiral interactions. The biological environment is conveniently modeled as a bath of harmonic oscillators. The resulting spin-boson model is adapted by a polaron transformation to derive the corresponding Born-Markov master equation with which we obtain the elastic and inelastic electron tunneling rates. We show that the inelastic tunneling through left- and right-handed enantiomers occurs with different rates. The discrimination mechanism depends on the ratio of tunneling frequency to localization frequency.

Chiral Cliffs: Investigating the Influence of Chirality on Binding Affinity.

PubMed

Schneider, Nadine; Lewis, Richard A; Fechner, Nikolas; Ertl, Peter

2018-05-11

Chirality is understood by many as a binary concept: a molecule is either chiral or it is not. In terms of the action of a structure on polarized light, this is indeed true. When examined through the prism of molecular recognition, the answer becomes more nuanced. In this work, we investigated chiral behavior on protein-ligand binding: when does chirality make a difference in binding activity? Chirality is a property of the 3D structure, so recognition also requires an appreciation of the conformation. In many situations, the bioactive conformation is undefined. We set out to address this by defining and using several novel 2D descriptors to capture general characteristic features of the chiral center. Using machine-learning methods, we built different predictive models to estimate if a chiral pair (a set of two enantiomers) might exhibit a chiral cliff in a binding assay. A set of about 3800 chiral pairs extracted from the ChEMBL23 database was used to train and test our models. By achieving an accuracy of up to 75 %, our models provide good performance in discriminating chiral cliffs from non-cliffs. More importantly, we were able to derive some simple guidelines for when one can reasonably use a racemate and when an enantiopure compound is needed in an assay. We critically discuss our results and show detailed examples of using our guidelines. Along with this publication we provide our dataset, our novel descriptors, and the Python code to rebuild the predictive models. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recursive model for the fragmentation of polarized quarks

NASA Astrophysics Data System (ADS)

Kerbizi, A.; Artru, X.; Belghobsi, Z.; Bradamante, F.; Martin, A.

2018-04-01

We present a model for Monte Carlo simulation of the fragmentation of a polarized quark. The model is based on string dynamics and the 3P0 mechanism of quark pair creation at string breaking. The fragmentation is treated as a recursive process, where the splitting function of the subprocess q →h +q' depends on the spin density matrix of the quark q . The 3P0 mechanism is parametrized by a complex mass parameter μ , the imaginary part of which is responsible for single spin asymmetries. The model has been implemented in a Monte Carlo program to simulate jets made of pseudoscalar mesons. Results for single hadron and hadron pair transverse-spin asymmetries are found to be in agreement with experimental data from SIDIS and e+e- annihilation. The model predictions on the jet-handedness are also discussed.

Semi-relativistic quark-antiquark potential models

NASA Astrophysics Data System (ADS)

Basdevant, J. L.; Boukraa, S.

We study the qualitative and quantitative properties of the spectrum of a two-body hamiltonian with relativistic kinematics. We show that this kinematics leads in a natural way to the observed features of light flavour (u, d, s) spectroscopy. After having established the basic properties of the operator √ p2 + m2 + V(r) in the cases of linear or logarithmic potentials, we show that, to first approximation, all q1 q2 meson states can be reproduced with a very simple universal flavour-independent potential whose parameters are directly related to basic physical quantities : the Regge slopes of light flavours and the quasi-logarithmic coupling strength of heavy quarks. We can derive equivalent effective non-relativistic hamiltonians which justify the successes of NR approaches. The main difficulties encountered, in particular in incorporating spin effects, appear to be due to the fact that, in phenomenological potential models, chiral symmetry and the ensuing Goldstone nature of the pion cannot be implemented in a natural way. Hence, such an approach can take its full predictive power only if it is based on a deeper field-theoretic level. Devant le succès spectaculaire des modèles potentiels pour la spectroscopie des états formés de quarks lourds (cc, bb, etc.), il est tentant d'essayer d'étendre de tels modèles aux états comprenant des quarks légers, u, d et s. En particulier, la spectroscopie des états mésoniques « lourds » est phénoménologiquement dominée par l'existence d'un potentiel confinant universel, quasi logarithmique entre 0,1 fm et 1 fm, tandis que celle des états légers se décrit de façon simple par des trajectoires de Regge linéaires qui ont une pente universelle. 11 est donc légitime de se demander s'il s'agit là de deux secteurs disjoints du monde hadronique, ou bien s'il existe une certaine unité dans la spectroscopie mésonique au plan phénoménologique. Cependant, en présence de quarks légers, voire de masse nulle, les

Quark fragmentation functions in NJL-jet model

NASA Astrophysics Data System (ADS)

Bentz, Wolfgang; Matevosyan, Hrayr; Thomas, Anthony

2014-09-01

We report on our studies of quark fragmentation functions in the Nambu-Jona-Lasinio (NJL) - jet model. The results of Monte-Carlo simulations for the fragmentation functions to mesons and nucleons, as well as to pion and kaon pairs (dihadron fragmentation functions) are presented. The important role of intermediate vector meson resonances for those semi-inclusive deep inelastic production processes is emphasized. Our studies are very relevant for the extraction of transverse momentum dependent quark distribution functions from measured scattering cross sections. We report on our studies of quark fragmentation functions in the Nambu-Jona-Lasinio (NJL) - jet model. The results of Monte-Carlo simulations for the fragmentation functions to mesons and nucleons, as well as to pion and kaon pairs (dihadron fragmentation functions) are presented. The important role of intermediate vector meson resonances for those semi-inclusive deep inelastic production processes is emphasized. Our studies are very relevant for the extraction of transverse momentum dependent quark distribution functions from measured scattering cross sections. Supported by Grant in Aid for Scientific Research, Japanese Ministry of Education, Culture, Sports, Science and Technology, Project No. 20168769.

Pion-nucleon scattering: from chiral perturbation theory to Roy-Steiner equations

NASA Astrophysics Data System (ADS)

Kubis, Bastian; Hoferichter, Martin; de Elvira, Jacobo Ruiz; Meißner, Ulf-G.

2016-11-01

Ever since Weinberg's seminal predictions of the pion-nucleon scattering amplitudes at threshold, this process has been of central interest for the study of chiral dynamics involving nucleons. The scattering lengths or the pion-nucleon σ-term are fundamental quantities characterizing the explicit breaking of chiral symmetry by means of the light quark masses. On the other hand, pion-nucleon dynamics also strongly affects the long-range part of nucleon-nucleon potentials, and hence has a far-reaching impact on nuclear physics. We discuss the fruitful combination of dispersion-theoretical methods, in the form of Roy-Steiner equations, with chiral dynamics to determine pion-nucleon scattering amplitudes at low energies with high precision.*

The Top Quark as a Window to Beyond the Standard Model Physics

NASA Astrophysics Data System (ADS)

Yu, Chiu-Tien

The top quark was the last of the Standard Model quarks to be discovered, and is of considerable interest. The closeness of the top quark mass to the electroweak scale is suggestive that the top quark could be closely related to the mechanisms for electroweak symmetry breaking. Any new physics in electroweak symmetry breaking models could then preferentially couple to the top quark, making the top quark a promising probe for new physics. In this thesis, we will explore two aspects of the top quark as a harbinger to new physics: the top forward-backward asymmetry as seen at the Tevatron and the search for stops. In this thesis, we will discuss the Asymmetric Left-Right Model (ALRM), a model that is based on the gauge group U'(1) x SU(2) x SU'(2) with couplings g' 1,g'2; and g' associated with the fields B',W,W', respectively, and show how this model can explain the top forwardbackward asymmetry. We will then explore the scalar sector of the ALRM, and provide a specific Higgs mechanism that provides the masses for the W' and Z' bosons. The top forward-backward asymmetry is a test of invariance of chargeconjugation. Thus, we look at the X-gluon model, a model that was motivated by the top forward-backward asymmetry, and show that one can look at the longitudinal polarization of the top-quark to test parity conservation. Finally, we investigate searches for stop squarks, the supersymmetric partner of the top quark, at the Large Hadron Collider (LHC) using shape-based analyses.

Physics of the Quark Model

ERIC Educational Resources Information Center

Young, Robert D.

1973-01-01

Discusses the charge independence, wavefunctions, magnetic moments, and high-energy scattering of hadrons on the basis of group theory and nonrelativistic quark model with mass spectrum calculated by first-order perturbation theory. The presentation is explainable to advanced undergraduate students. (CC)

B -meson decay constants from 2 + 1 -flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks

DOE PAGES

Christ, Norman H.; Flynn, Jonathan M.; Izubuchi, Taku; ...

2015-03-10

We calculate the B-meson decay constants f B, f Bs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as M π ≈ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b quarks we use the anisotropic clovermore » action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(α sa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain f B0 = 199.5(12.6) MeV, f B+=195.6(14.9) MeV, f Bs=235.4(12.2) MeV, f Bs/f B0=1.197(50), and f Bs/f B+=1.223(71), where the errors are statistical and total systematic added in quadrature. Finally, these results are in good agreement with other published results and provide an important independent cross-check of other three-flavor determinations of B-meson decay constants using staggered light quarks.« less

B-meson decay constants from 2+1-flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks

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

Christ, Norman H.; Flynn, Jonathan M.; Izubuchi, Taku

2015-03-10

We calculate the B-meson decay constants f B, f Bs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as M π ≈ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action withmore » the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(α sa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain f B0 = 196.2(15.7) MeV, f B+ = 195.4(15.8) MeV, f Bs = 235.4(12.2) MeV, f Bs/f B0 = 1.193(59), and f Bs/f B+ = 1.220(82), where the errors are statistical and total systematic added in quadrature. In addition, these results are in good agreement with other published results and provide an important independent cross check of other three-flavor determinations of B-meson decay constants using staggered light quarks.« less

Prediction of new Quarks, Generations and Quark Masses

NASA Astrophysics Data System (ADS)

Lach, Thedore

2002-04-01

The Standard model currently suggests no relationship between the quark and lepton masses. The CBM (model) of the nucleus has resulted in the prediction of two new quarks, an up quark mass of 237.31 MeV/c2 and a dn quark mass of 42.392 MeV/c2. These two new quarks help explain the numerical relationship between all the quark and lepton masses in a single function. The mass of each SNU-P (quark or lepton) is just the geometric mean of two related SNU-Ps, either in the same generation or in the same family. This numerology predicts the following masses for the electron family: 0.511000 (electron), 7.743828 (predicted), 117.3520, 1778.38, 26950.08 MeV. The resulting slope of these masses when plotted on semi log paper is "e" to 5 significant figures using the currently accepted mass for Tau. This theory suggests that all the "dn like" quarks have a mass of just 10X multiples of 4.24 MeV (the mass of the "d" quark). The first 3 "up like" quark masses are 38, 237 and 1500 MeV. This theory also predicts a new heavy generation with a lepton mass of 27 GeV, a "dn like" quark of 42.4 GeV, and an "up like" quark of 65 GeV. Significant evidence already exists for the existence of these quarks, and lepton.

Towards a Unified Quark-Hadron-Matter Equation of State for Applications in Astrophysics and Heavy-Ion Collisions

NASA Astrophysics Data System (ADS)

Bastian, Niels-Uwe; Blaschke, David; Fischer, Tobias; Röpke, Gerd

2018-05-01

We outline an approach to a unified equation of state for quark-hadron matter on the basis of a $\\Phi-$derivable approach to the generalized Beth-Uhlenbeck equation of state for a cluster decomposition of thermodynamic quantities like the density. To this end we summarize the cluster virial expansion for nuclear matter and demonstrate the equivalence of the Green's function approach and the $\\Phi-$derivable formulation. For an example, the formation and dissociation of deuterons in nuclear matter is discussed. We formulate the cluster $\\Phi-$derivable approach to quark-hadron matter which allows to take into account the specifics of chiral symmetry restoration and deconfinement in triggering the Mott-dissociation of hadrons. This approach unifies the description of a strongly coupled quark-gluon plasma with that of a medium-modified hadron resonance gas description which are contained as limiting cases. The developed formalism shall replace the common two-phase approach to the description of the deconfinement and chiral phase transition that requires a phase transition construction between separately developed equations of state for hadronic and quark matter phases. Applications to the phenomenology of heavy-ion collisions and astrophysics are outlined.

1/Nc expansion and the spin-flavor structure of the quark interaction in the constituent quark model

NASA Astrophysics Data System (ADS)

Pirjol, Dan; Schat, Carlos

2010-12-01

We study the hierarchy of the coefficients in the 1/Nc expansion for the negative parity L=1 excited baryons from the perspective of the constituent quark model. This is related to the problem of determining the spin-flavor structure of the quark interaction. The most general two-body scalar interaction between quarks contains the spin-flavor structures t1at2a,s→1·s→2 and s→1·s→2t1at2a. We show that in the limit of a zero range interaction all these structures are matched onto the same hadronic mass operator Sc2, which gives a possible explanation for the dominance of this operator in the 1/Nc expansion for the L=1 states and implies that in this limit it is impossible to distinguish between these different spin-flavor structures. Modeling a finite range interaction through the exchange of a vector and pseudoscalar meson, we propose a test for the spin-flavor dependence of the quark forces. For the scalar part of the quark interaction, we find that both pion exchange and gluon exchange are compatible with the data.

Transverse momentum correlations of quarks in recursive jet models

NASA Astrophysics Data System (ADS)

Artru, X.; Belghobsi, Z.; Redouane-Salah, E.

2016-08-01

In the symmetric string fragmentation recipe adopted by PYTHIA for jet simulations, the transverse momenta of successive quarks are uncorrelated. This is a simplification but has no theoretical basis. Transverse momentum correlations are naturally expected, for instance, in a covariant multiperipheral model of quark hadronization. We propose a simple recipe of string fragmentation which leads to such correlations. The definition of the jet axis and its relation with the primordial transverse momentum of the quark is also discussed.

Quarks, Symmetries and Strings - a Symposium in Honor of Bunji Sakita's 60th Birthday

NASA Astrophysics Data System (ADS)

Kaku, M.; Jevicki, A.; Kikkawa, K.

1991-04-01

The Table of Contents for the full book PDF is as follows: * Preface * Evening Banquet Speech * I. Quarks and Phenomenology * From the SU(6) Model to Uniqueness in the Standard Model * A Model for Higgs Mechanism in the Standard Model * Quark Mass Generation in QCD * Neutrino Masses in the Standard Model * Solar Neutrino Puzzle, Horizontal Symmetry of Electroweak Interactions and Fermion Mass Hierarchies * State of Chiral Symmetry Breaking at High Temperatures * Approximate |ΔI| = 1/2 Rule from a Perspective of Light-Cone Frame Physics * Positronium (and Some Other Systems) in a Strong Magnetic Field * Bosonic Technicolor and the Flavor Problem * II. Strings * Supersymmetry in String Theory * Collective Field Theory and Schwinger-Dyson Equations in Matrix Models * Non-Perturbative String Theory * The Structure of Non-Perturbative Quantum Gravity in One and Two Dimensions * Noncritical Virasoro Algebra of d < 1 Matrix Model and Quantized String Field * Chaos in Matrix Models ? * On the Non-Commutative Symmetry of Quantum Gravity in Two Dimensions * Matrix Model Formulation of String Field Theory in One Dimension * Geometry of the N = 2 String Theory * Modular Invariance form Gauge Invariance in the Non-Polynomial String Field Theory * Stringy Symmetry and Off-Shell Ward Identities * q-Virasoro Algebra and q-Strings * Self-Tuning Fields and Resonant Correlations in 2d-Gravity * III. Field Theory Methods * Linear Momentum and Angular Momentum in Quaternionic Quantum Mechanics * Some Comments on Real Clifford Algebras * On the Quantum Group p-adics Connection * Gravitational Instantons Revisited * A Generalized BBGKY Hierarchy from the Classical Path-Integral * A Quantum Generated Symmetry: Group-Level Duality in Conformal and Topological Field Theory * Gauge Symmetries in Extended Objects * Hidden BRST Symmetry and Collective Coordinates * Towards Stochastically Quantizing Topological Actions * IV. Statistical Methods * A Brief Summary of the s-Channel Theory of

Low-temperature behavior of the quark-meson model

NASA Astrophysics Data System (ADS)

Tripolt, Ralf-Arno; Schaefer, Bernd-Jochen; von Smekal, Lorenz; Wambach, Jochen

2018-02-01

We revisit the phase diagram of strong-interaction matter for the two-flavor quark-meson model using the functional renormalization group. In contrast to standard mean-field calculations, an unusual phase structure is encountered at low temperatures and large quark chemical potentials. In particular, we identify a regime where the pressure decreases with increasing temperature and discuss possible reasons for this unphysical behavior.

New mathematic model for predicting chiral separation using molecular docking: mechanism of chiral recognition of triadimenol analogues.

PubMed

Zhang, Guoqing; Sun, Qingyan; Hou, Ying; Hong, Zhanying; Zhang, Jun; Zhao, Liang; Zhang, Hai; Chai, Yifeng

2009-07-01

The purpose of this paper was to study the enantioseparation mechanism of triadimenol compounds by carboxymethylated (CM)-beta-CD mediated CE. All the enantiomers were separated under the same experimental conditions to study the chiral recognition mechanism using a 30 mM sodium dihydrogen phosphate buffer at pH 2.2 adjusted by phosphoric acid. The inclusion courses between CM-beta-CD and enantiomers were investigated by the means of molecular docking technique. It was found that there were at least three points (one hydrophobic bond and two hydrogen bonds) involved in the interaction of each enantiomer with the chiral selectors. A new mathematic model has been built up based on the results of molecular mechanics calculations, which could analyze the relationship between the resolution of enantioseparation and the interaction energy in the docking area. Comparing the results of the separation by CE, the established mathematic model demonstrated good capability to predict chiral separation of triadimenol enantiomers using CM-beta-CD mediated CE.

Lattice spin models for non-Abelian chiral spin liquids

DOE PAGES

Lecheminant, P.; Tsvelik, A. M.

2017-04-26

Here, we suggest a class of two-dimensional lattice spin Hamiltonians describing non-Abelian SU(2) chiral spin liquids—spin analogs of fractional non-Abelian quantum Hall states—with gapped bulk and gapless chiral edge excitations described by the SU(2) n Wess-Zumino-Novikov-Witten conformal field theory. The models are constructed from an array of generalized spin-n/2 ladders with multi-spin-exchange interactions which are coupled by isolated spins. Such models allow a controllable analytic treatment starting from the one-dimensional limit and are characterized by a bulk gap and non-Abelian SU(2) n gapless edge excitations.

Quark cluster model for deep-inelastic lepton-deuteron scattering

NASA Astrophysics Data System (ADS)

Yen, G.; Vary, J. P.; Harindranath, A.; Pirner, H. J.

1990-10-01

We evaluate the contribution of quasifree nucleon knockout and of inelastic lepton-nucleon scattering in inclusive electron-deuteron reactions at large momentum transfer. We examine the degree of quantitative agreement with deuteron wave functions from the Reid soft-core and Bonn realistic nucleon-nucleon interactions. For the range of data available there is strong sensitivity to the tensor correlations which are distinctively different in these two deuteron models. At this stage of the analyses the Reid soft-core wave function provides a reasonable description of the data while the Bonn wave function does not. We then include a six-quark cluster component whose relative contribution is based on an overlap criterion and obtain a good description of all the data with both interactions. The critical separation at which overlap occurs (formation of six-quark clusters) is taken to be 1.0 fm and the six-quark cluster probability is 4.7% for Reid and 5.4% for Bonn. As a consequence the quark cluster model with either Reid or Bonn wave function describe the SLAC inclusive electron-deuteron scattering data equally well. We then show how additional data would be decisive in resolving which model is ultimately more correct.

Hadron spectroscopy with dynamical chirally improved fermions

NASA Astrophysics Data System (ADS)

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

2009-03-01

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

From quarks and gluons to baryon form factors

PubMed Central

Eichmann, Gernot

2012-01-01

I briefly summarize recent results for nucleon and Δ(1232) electromagnetic, axial and transition form factors in the Dyson–Schwinger approach. The calculation of the current diagrams from the quark–gluon level enables a transparent discussion of common features such as: the implications of dynamical chiral symmetry breaking and quark orbital angular momentum, the timelike structure of the form factors, and their interpretation in terms of missing pion-cloud effects. PMID:26766879

Physical results from 2+1 flavor domain wall QCD and SU(2) chiral perturbation theory

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

Allton, C.; Antonio, D. J.; Boyle, P. A.

2008-12-01

We have simulated QCD using 2+1 flavors of domain wall quarks and the Iwasaki gauge action on a (2.74 fm){sup 3} volume with an inverse lattice scale of a{sup -1}=1.729(28) GeV. The up and down (light) quarks are degenerate in our calculations and we have used four values for the ratio of light quark masses to the strange (heavy) quark mass in our simulations: 0.217, 0.350, 0.617, and 0.884. We have measured pseudoscalar meson masses and decay constants, the kaon bag parameter B{sub K}, and vector meson couplings. We have used SU(2) chiral perturbation theory, which assumes only the upmore » and down quark masses are small, and SU(3) chiral perturbation theory to extrapolate to the physical values for the light quark masses. While next-to-leading order formulas from both approaches fit our data for light quarks, we find the higher-order corrections for SU(3) very large, making such fits unreliable. We also find that SU(3) does not fit our data when the quark masses are near the physical strange quark mass. Thus, we rely on SU(2) chiral perturbation theory for accurate results. We use the masses of the {omega} baryon, and the {pi} and K mesons to set the lattice scale and determine the quark masses. We then find f{sub {pi}}=124.1(3.6){sub stat}(6.9){sub syst} MeV, f{sub K}=149.6(3.6){sub stat}(6.3){sub syst} MeV, and f{sub K}/f{sub {pi}}=1.205(0.018){sub stat}(0.062){sub syst}. Using nonperturbative renormalization to relate lattice regularized quark masses to regularization independent momentum scheme masses, and perturbation theory to relate these to MS, we find m{sub ud}{sup MS}(2 GeV)=3.72(0.16){sub stat}(0.33){sub ren}(0.18){sub syst} MeV, m{sub s}{sup MS}(2 GeV)=107.3(4.4){sub stat}(9.7){sub ren}(4.9){sub syst} MeV, and m-tilde{sub ud} ratio m-tilde{sub s}=1 ratio 28.8(0.4){sub stat}(1.6){sub syst}. For the kaon bag parameter, we find B{sub K}{sup MS}(2 GeV)=0.524(0.010){sub stat}(0.013){sub ren}(0.025){sub syst}. Finally, for the ratios of the couplings of

Transport and collective radiance in a basic quantum chiral optical model

NASA Astrophysics Data System (ADS)

Kornovan, D. F.; Petrov, M. I.; Iorsh, I. V.

2017-09-01

In our work, we theoretically study the dynamics of a single excitation in a one-dimensional array of two-level systems, which are chirally coupled through a single mode waveguide. The chirality is achieved owing to a strong optical spin-locking effect, which in an ideal case gives perfect unidirectional excitation transport. We obtain a simple analytical solution for a single excitation dynamics in the Markovian limit, which directly shows the tolerance of the system with respect to the fluctuations of emitters position. We also show that the Dicke state, which is well known to be superradiant, has twice lower emission rate in the case of unidirectional quantum interaction. Our model is supported and verified with the numerical computations of quantum emitters coupled via surface plasmon modes in a metallic nanowire. The obtained results are based on a very general model and can be applied to any chirally coupled system that gives a new outlook on quantum transport in chiral nanophotonics.

Chiral geometry in multiple chiral doublet bands

NASA Astrophysics Data System (ADS)

Zhang, Hao; Chen, Qibo

2016-02-01

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

Dark matter admixed strange quark stars in the Starobinsky model

NASA Astrophysics Data System (ADS)

Lopes, Ilídio; Panotopoulos, Grigoris

2018-01-01

We compute the mass-to-radius profiles for dark matter admixed strange quark stars in the Starobinsky model of modified gravity. For quark matter, we assume the MIT bag model, while self-interacting dark matter inside the star is modeled as a Bose-Einstein condensate with a polytropic equation of state. We numerically integrate the structure equations in the Einstein frame, adopting the two-fluid formalism, and we treat the curvature correction term nonperturbatively. The effects on the properties of the stars of the amount of dark matter as well as the higher curvature term are investigated. We find that strange quark stars (in agreement with current observational constraints) with the highest masses are equally affected by dark matter and modified gravity.

Search for Quark-Lepton Compositeness in the Dimuon Final State at DØ

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

Xuan, Nguyen Phuoc

2005-04-01

We used the upgraded DØ detector at the Tevatron at √s = 1.96 TeV to collect data in a search for a compositeness signature of quarks and leptons. This analysis uses an integrated luminosity of 400 pb -1. The high-mass dimuon mass spectrum is compared with that predicted by Drell-Yan (DY) scattering, modified by a contact interaction. This interaction is parameterized by a compositeness energy scale factor Λ. Preliminary limits on Λ are set at the 95% confidence level for constructive and destructive interference between the DY amplitude and the contact interaction for various quark and lepton chiralities.

Investigation of the chiral antiferromagnetic Heisenberg model using projected entangled pair states

NASA Astrophysics Data System (ADS)

Poilblanc, Didier

2017-09-01

A simple spin-1/2 frustrated antiferromagnetic Heisenberg model (AFHM) on the square lattice—including chiral plaquette cyclic terms—was argued [A. E. B. Nielsen, G. Sierra, and J. I. Cirac, Nat. Commun. 4, 2864 (2013), 10.1038/ncomms3864] to host a bosonic Kalmeyer-Laughlin (KL) fractional quantum Hall ground state [V. Kalmeyer and R. B. Laughlin, Phys. Rev. Lett. 59, 2095 (1987), 10.1103/PhysRevLett.59.2095]. Here, we construct generic families of chiral projected entangled pair states (chiral PEPS) with low bond dimension (D =3 ,4 ,5 ) which, upon optimization, provide better variational energies than the KL Ansatz. The optimal D =3 PEPS exhibits chiral edge modes described by the Wess-Zumino-Witten SU(2) 1 model, as expected for the KL spin liquid. However, we find evidence that, in contrast to the KL state, the PEPS spin liquids have power-law dimer-dimer correlations and exhibit a gossamer long-range tail in the spin-spin correlations. We conjecture that these features are genuine to local chiral AFHM on bipartite lattices.

[Topological models of retention index of thin-layer chromatogram for chiral organic acids].

PubMed

Li, Mingjian; Wang, Yuxiao; Feng, Hui; Feng, Changjun

2014-03-01

On the basis of Kier's molecular connectivity indices and conjugated matrix, novel molecular connectivity indices ((m) G(t)(v)) were defined and calculated for 18 chiral hydroxyl acids and amino acids. The chiral connectivity indices ((m)C(t)(v)) were introduced by extending (m)G(t)(v): (m)C(t)(v) = (m)G(t)(v) x w(j), where w(j) is the chiral index. The quantitative structure-retention index relationship (QSRR) between the retention index (R(M)) of thin-layer chromatogram for the chiral organic acids and (m)C(t)(v) was studied by multivariate statistical regression. By leaps-and-bounds regression analysis, the best four-parameter QSRR model was set up, and the traditional correlation coefficient (R2) and the cross-validation correlation coefficient (Q2) of leave-one-out (LOO) were 0.973 and 0.950, respectively. The results demonstrated that the model was highly reliable and had good predictive ability from the point of view of statistics. From the four parameters (0C(p)(v), 2C(p)(v), C(ch),(v), 5C(p)(v)) of the model, it is known that the dominant influence factors of the retention index were the molecular structure characteristics of two-dimensional and the space factors: the chiral characteristics, the flexibility and the puckered degree of molecules for the chiral organic acids. The results showed that the new parameter mC(t)(v) had good rationality and efficiency for the retention indices of the chiral organic acids. Therefore, an effective method was provided to predict the retention indices of the chiral organic acids.

The isospin strange asymmetry from the chiral effective theory

NASA Astrophysics Data System (ADS)

Trevisan, Luis Augusto; Mirez, Carlos

2018-05-01

The proposal of the present work is to study the difference between the strange quark-antiquark amount in the proton and neutron. For this purpose, the possible nucleon-hyperon-kaon fluctuations are analyzed with the effective chiral theory. The small difference of particle masses is shown to be in the origin of this isospin asymmetry. The dependence of the results on the mass cutoff parameter and with the coupling constants is analyzed.

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

NASA Astrophysics Data System (ADS)

Mohler, Daniel; Schaefer, Stefan; Simeth, Jakob

2018-03-01

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

Beta functions in Chirally deformed supersymmetric sigma models in two dimensions

NASA Astrophysics Data System (ADS)

Vainshtein, Arkady

2016-10-01

We study two-dimensional sigma models where the chiral deformation diminished the original 𝒩 = (2, 2) supersymmetry to the chiral one, 𝒩 = (0, 2). Such heterotic models were discovered previously on the world sheet of non-Abelian stringy solitons supported by certain four-dimensional 𝒩 = 1 theories. We study geometric aspects and holomorphic properties of these models, and derive a number of exact expressions for the β functions in terms of the anomalous dimensions analogous to the NSVZ β function in four-dimensional Yang-Mills. Instanton calculus provides a straightforward method for the derivation.

Beta Functions in Chirally Deformed Supersymmetric Sigma Models in Two Dimensions

NASA Astrophysics Data System (ADS)

Vainshtein, Arkady

We study two-dimensional sigma models where the chiral deformation diminished the original 𝒩 =(2, 2) supersymmetry to the chiral one, 𝒩 =(0, 2). Such heterotic models were discovered previously on the world sheet of non-Abelian stringy solitons supported by certain four-dimensional 𝒩 = 1 theories. We study geometric aspects and holomorphic properties of these models, and derive a number of exact expressions for the β functions in terms of the anomalous dimensions analogous to the NSVZ β function in four-dimensional Yang-Mills. Instanton calculus provides a straightforward method for the derivation.

Top quark pair production and top quark properties at CDF

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

Moon, Chang-Seong

2016-06-02

We present the most recent measurements of top quark pairs production and top quark properties in proton-antiproton collisions with center-of-mass energy of 1.96 TeV using CDF II detector at the Tevatron. The combination of top pair production cross section measurements and the direct measurement of top quark width are reported. The test of Standard Model predictions for top quark decaying intomore » $b$-quarks, performed by measuring the ratio $R$ between the top quark branching fraction to $b$-quark and the branching fraction to any type of down quark is shown. The extraction of the CKM matrix element $$|V_{tb}|$$ from the ratio $R$ is discussed. We also present the latest measurements on the forward-backward asymmetry ($$A_{FB}$$) in top anti-top quark production. With the full CDF Run II data set, the measurements are performed in top anti-top decaying to final states that contain one or two charged leptons (electrons or muons). In addition, we combine the results of the leptonic forward-backward asymmetry in $$t\\bar t$$ system between the two final states. All the results show deviations from the next-to-leading order (NLO) standard model (SM) calculation.« less

Degenerate and chiral states in the extended Heisenberg model on the kagome lattice

NASA Astrophysics Data System (ADS)

Gómez Albarracín, F. A.; Pujol, P.

2018-03-01

We present a study of the low-temperature phases of the antiferromagnetic extended classical Heisenberg model on the kagome lattice, up to third-nearest neighbors. First, we focus on the degenerate lines in the boundaries of the well-known staggered chiral phases. These boundaries have either semiextensive or extensive degeneracy, and we discuss the partial selection of states by thermal fluctuations. Then, we study the model under an external magnetic field on these lines and in the staggered chiral phases. We pay particular attention to the highly frustrated point, where the three exchange couplings are equal. We show that this point can be mapped to a model with spin-liquid behavior and nonzero chirality. Finally, we explore the effect of Dzyaloshinskii-Moriya (DM) interactions in two ways: a homogeneous and a staggered DM interaction. In both cases, there is a rich low-temperature phase diagram, with different spontaneously broken symmetries and nontrivial chiral phases.

Valence-quark distribution functions in the kaon and pion

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

Chen, Chen; Chang, Lei; Roberts, Craig D.

2016-04-18

We describe expressions for pion and kaon dressed-quark distribution functions that incorporate contributions from gluons which bind quarks into these mesons and hence overcome a flaw of the commonly used handbag approximation. The distributions therewith obtained are purely valence in character, ensuring that dressed quarks carry all the meson’s momentum at a characteristic hadronic scale and vanish as ( 1 - x ) 2 when Bjorken- x → 1 . Comparing such distributions within the pion and kaon, it is apparent that the size of S U ( 3 ) -flavor symmetry breaking in meson parton distribution functions is modulatedmore » by the flavor dependence of dynamical chiral symmetry breaking. Corrections to these leading-order formulas may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea quarks. Working with available empirical information, we build an algebraic framework that is capable of expressing the principal impact of both classes of corrections. This enables a realistic comparison with experiment which allows us to identify and highlight basic features of measurable pion and kaon valence-quark distributions. We find that whereas roughly two thirds of the pion’s light-front momentum is carried by valence dressed quarks at a characteristic hadronic scale; this fraction rises to 95% in the kaon; evolving distributions with these features to a scale typical of available Drell-Yan data produces a kaon-to-pion ratio of u -quark distributions that is in agreement with the single existing data set, and predicts a u -quark distribution within the pion that agrees with a modern reappraisal of π N Drell-Yan data. Precise new data are essential in order to validate this reappraisal and because a single modest-quality measurement of the kaon-to-pion ratio cannot be considered definitive.« less

Spin Polarization and Color Superconductivity in the Nambu-Jona-Lasinio Model

NASA Astrophysics Data System (ADS)

Matsuoka, Hiroaki; Tsue, Yasuhiko; da Providência, João; Providência, Constança; Yamamura, Masatoshi

In this research we study a possibility that spins of quarks may polarize at large quark chemical potential. In order to discuss this possibility, we introduce a tensor-type interaction into the Nambu-Jona-Lasinio model. Here we pay attention to the relationship between chiral condensate, spin polarization and color superconductivity. It is shown that, at large quark chemical potential and low temperature, the coexisting phase where both the spin-polarized condensate and color superconducting gap exist together may be realized.

FLRW cosmological models with quark and strange quark matters in f(R,T) gravity

NASA Astrophysics Data System (ADS)

Nagpal, Ritika; Singh, J. K.; Aygün, S.

2018-06-01

In this paper, we have studied the magnetized quark matter (QM) and strange quark matter (SQM) distributions in the presence of f(R,T) gravity in the background of Friedmann-Lemaître-Robertson-Walker (FLRW) metric. To get exact solutions of modified field equations we have used f(R,T ) = R + 2 f(T) model given by Harko et al. with two different parametrization of geometrical parameters i.e. the parametrization of the deceleration parameter q , and the scale factor a in hybrid expansion form. Also, we have obtained Einstein Static Universe (ESU) solutions for QM and SQM distributions in f(R,T) gravity and General Relativity (GR). All models in f(R,T) gravity and GR for FRW and ESU Universes with QM also SQM distributions, we get zero magnetic field. These results agree with the solutions of Aktaş and Aygün in f(R,T) gravity. However, we have also discussed the physical consequences of our obtained models.

General structure of democratic mass matrix of quark sector in E6 model

NASA Astrophysics Data System (ADS)

Ciftci, R.; ćiftci, A. K.

2016-03-01

An extension of the Standard Model (SM) fermion sector, which is inspired by the E6 Grand Unified Theory (GUT) model, might be a good candidate to explain a number of unanswered questions in SM. Existence of the isosinglet quarks might explain great mass difference of bottom and top quarks. Also, democracy on mass matrix elements is a natural approach in SM. In this study, we have given general structure of Democratic Mass Matrix (DMM) of quark sector in E6 model.

Quark mass variations of nuclear forces, BBN, and all that

NASA Astrophysics Data System (ADS)

Meissner, Ulf-G.

2014-03-01

In this talk, I discuss the modifications of the nuclear forces due to variations of the light quark masses and of the fine structure constant. This is based on the chiral nuclear effective field theory, that successfully describes a large body of data. The generation of the light elements in the Big Bang Nucleosynthesis provides important constraints on these modifications. In addition, I discuss the role of the anthropic principle in the triple-alpha process that underlies carbon and oxygen generation in hot stars. It appears that a fine-tuning of the quark masses and the fine structure constant within 2 to 3 per cent is required to make life on Earth viable. Supported in part by DFG, HGF and the BMBF.

Emergent Chiral Spin State in the Mott Phase of a Bosonic Kane-Mele-Hubbard Model

NASA Astrophysics Data System (ADS)

Plekhanov, Kirill; Vasić, Ivana; Petrescu, Alexandru; Nirwan, Rajbir; Roux, Guillaume; Hofstetter, Walter; Le Hur, Karyn

2018-04-01

Recently, the frustrated X Y model for spins 1 /2 on the honeycomb lattice has attracted a lot of attention in relation with the possibility to realize a chiral spin liquid state. This model is relevant to the physics of some quantum magnets. Using the flexibility of ultracold atom setups, we propose an alternative way to realize this model through the Mott regime of the bosonic Kane-Mele-Hubbard model. The phase diagram of this model is derived using bosonic dynamical mean-field theory. Focusing on the Mott phase, we investigate its magnetic properties as a function of frustration. We do find an emergent chiral spin state in the intermediate frustration regime. Using exact diagonalization we study more closely the physics of the effective frustrated X Y model and the properties of the chiral spin state. This gapped phase displays a chiral order, breaking time-reversal and parity symmetry, but is not topologically ordered (the Chern number is zero).

Prediction of new Quarks, Generations & low Mass Quarks

NASA Astrophysics Data System (ADS)

Lach, Theodore

2003-04-01

The CBM (model) of the nucleus has resulted in the prediction of two new quarks, an "up" quark of mass 237.31 MeV/c2 and a "dn" quark of mass 42.392 MeV/c2. These two new predicted quarks helped to determine that the masses of the quarks and leptons are all related by a geometric progression relationship. The mass of each quark or lepton is just the "geometric mean" of two related elementary particles, either in the same generation or in the same family. This numerology predicts the following masses for the electron family: 0.511000 (electron), 7.74 (predicted), 117.3, 1778.4 (tau), 26950.1 MeV. The geometric ratio of this progression is 15.154 (e to the power e). The mass of the tau in this theory agrees very well with accepted values. This theory suggests that all the "dn like" quarks have a mass of just 10X multiples of 4.24 MeV (the mass of the "d" quark). The first 3 "up like" quark masses are 38, 237.31 and 1500 MeV. This theory also predicts a new heavy generation with a lepton mass of 27 GeV, a "dn like" quark of 42.4 GeV, and an "up like" quark of 65 GeV. Significant evidence already exists for the existence of these new quarks, and lepton. Ref. Masses of the Sub-Nuclear Particles, nucl-th/ 0008026, @ http://xxx.lanl.gov. Infinite Energy, Vol 5, issue 30.

Numerical modelling of chirality-induced bi-directional swimming of artificial flagella

PubMed Central

Namdeo, S.; Khaderi, S. N.; Onck, P. R.

2014-01-01

Biomimetic micro-swimmers can be used for various medical applications, such as targeted drug delivery and micro-object (e.g. biological cells) manipulation, in lab-on-a-chip devices. Bacteria swim using a bundle of flagella (flexible hair-like structures) that form a rotating cork-screw of chiral shape. To mimic bacterial swimming, we employ a computational approach to design a bacterial (chirality-induced) swimmer whose chiral shape and rotational velocity can be controlled by an external magnetic field. In our model, we numerically solve the coupled governing equations that describe the system dynamics (i.e. solid mechanics, fluid dynamics and magnetostatics). We explore the swimming response as a function of the characteristic dimensionless parameters and put special emphasis on controlling the swimming direction. Our results provide fundamental physical insight on the chirality-induced propulsion, and it provides guidelines for the design of magnetic bi-directional micro-swimmers. PMID:24511253

Connected, disconnected and strange quark contributions to HVP

NASA Astrophysics Data System (ADS)

Bijnens, Johan; Relefors, Johan

2016-11-01

We calculate all neutral vector two-point functions in Chiral Perturbation Theory (ChPT) to two-loop order and use these to estimate the ratio of disconnected to connected contributions as well as contributions involving the strange quark. We extend the ratio of -1/10 derived earlier in two flavour ChPT at one-loop order to a large part of the higher order contributions and discuss corrections to it. Our final estimate of the ratio disconnected to connected is negative and a few % in magnitude.

Enantioselectively controlled release of chiral drug (metoprolol) using chiral mesoporous silica materials

NASA Astrophysics Data System (ADS)

Guo, Zhen; Du, Yu; Liu, Xianbin; Ng, Siu-Choon; Chen, Yuan; Yang, Yanhui

2010-04-01

Chiral porous materials have attracted burgeoning attention on account of their potential applications in many areas, such as enantioseparation, chiral catalysis, chemical sensors and drug delivery. In this report, chiral mesoporous silica (CMS) materials with various pore sizes and structures were prepared using conventional achiral templates (other than chiral surfactant) and a chiral cobalt complex as co-template. The synthesized CMS materials were characterized by x-ray diffraction, nitrogen physisorption, scanning electron microscope and transmission electron microscope. These CMS materials, as carriers, were demonstrated to be able to control the enantioselective release of a representative chiral drug (metoprolol). The release kinetics, as modeled by the power law equation, suggested that the release profiles of metoprolol were remarkably dependent on the pore diameter and pore structure of CMS materials. More importantly, R- and S-enantiomers of metoprolol exhibited different release kinetics on CMS compared to the corresponding achiral mesoporous silica (ACMS), attributable to the existence of local chirality on the pore wall surface of CMS materials. The chirality of CMS materials on a molecular level was further substantiated by vibrational circular dichroism measurements.

Dissipationless Hall current in dense quark matter in a magnetic field

DOE PAGES

Ferrer, Efrain J.; de la Incera, V.

2017-03-29

Here, we show the realization of axion electrodynamics within the Dual Chiral Density Wave phase of dense quark matter in the presence of a magnetic field. This system exhibits an anomalous dissipationless Hall current perpendicular to the magnetic field and an anomalous electric charge density. This connection to topological insulators and 3D optical lattices, as well as possible implications for heavy-ion collisions and neutron stars are outlined.

The Quark - A Decade Later

ERIC Educational Resources Information Center

Dakin, James T.

1974-01-01

Reviews theoretical principles underlying the quark model. Indicates that the agreement with experimental results and the understanding of the quark-quark force are two hurdles for the model to survive in the future. (CC)

QCD In Extreme Conditions

NASA Astrophysics Data System (ADS)

Wilczek, Frank

Introduction Symmetry and the Phenomena of QCD Apparent and Actual Symmetries Asymptotic Freedom Confinement Chiral Symmetry Breaking Chiral Anomalies and Instantons High Temperature QCD: Asymptotic Properties Significance of High Temperature QCD Numerical Indications for Quasi-Free Behavior Ideas About Quark-Gluon Plasma Screening Versus Confinement Models of Chiral Symmetry Breaking More Refined Numerical Experiments High-Temperature QCD: Phase Transitions Yoga of Phase Transitions and Order Parameters Application to Glue Theories Application to Chiral Transitions Close Up on Two Flavors A Genuine Critical Point! (?) High-Density QCD: Methods Hopes, Doubts, and Fruition Another Renormalization Group Pairing Theory Taming the Magnetic Singularity High-Density QCD: Color-Flavor Locking and Quark-Hadron Continuity Gauge Symmetry (Non)Breaking Symmetry Accounting Elementary Excitations A Modified Photon Quark-Hadron Continuity Remembrance of Things Past More Quarks Fewer Quarks and Reality

Electromagnetic axial anomaly in a generalized linear sigma model

NASA Astrophysics Data System (ADS)

Fariborz, Amir H.; Jora, Renata

2017-06-01

We construct the electromagnetic anomaly effective term for a generalized linear sigma model with two chiral nonets, one with a quark-antiquark structure, the other one with a four-quark content. We compute in the leading order of this framework the decays into two photons of six pseudoscalars: π0(137 ), π0(1300 ), η (547 ), η (958 ), η (1295 ) and η (1760 ). Our results agree well with the available experimental data.

General structure of democratic mass matrix of quark sector in E{sub 6} model

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

Ciftci, R., E-mail: rciftci@cern.ch; Çiftci, A. K., E-mail: abbas.kenan.ciftci@cern.ch

2016-03-25

An extension of the Standard Model (SM) fermion sector, which is inspired by the E{sub 6} Grand Unified Theory (GUT) model, might be a good candidate to explain a number of unanswered questions in SM. Existence of the isosinglet quarks might explain great mass difference of bottom and top quarks. Also, democracy on mass matrix elements is a natural approach in SM. In this study, we have given general structure of Democratic Mass Matrix (DMM) of quark sector in E6 model.

Accidental symmetries and massless quarks in the economical 3-3-1 model

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

Montero, J. C.; Sánchez–Vega, B. L.

In the framework of a 3-3-1 model with a minimal scalar sector, known as the economical 3-3-1 model, we study its capabilities of generating realistic quark masses. After a detailed study of the symmetries of the model, before and after the spontaneous symmetry breaking, we find a remaining axial symmetry that prevents some quarks from gaining mass at all orders in perturbation theory. Since this accidental symmetry is anomalous, we also consider briefly the possibility of generating their masses for nonperturbative effects. However, we find that nonperturbative effects are not enough to generate the measured masses for the three masslessmore » quarks. Hence, these results imply that the economical 3-3-1 model is not a realistic description of the electroweak interaction.« less

Initial state q q g correlations as a background for the chiral magnetic effect in collision of small systems

NASA Astrophysics Data System (ADS)

Kovner, Alex; Lublinsky, Michael; Skokov, Vladimir

2017-11-01

Motivated by understanding the background to chiral magnetic effect in proton-nucleus collisions from first principles, we compute the three particle correlation in the projectile wave function. We extract the correlations between two quarks and one gluon in the framework of the color glass condensate. This is related to the same-charge correlation of the conventional observable for the chiral magnetic effect. We show that there are two different contributions to this correlation function. One contribution is rapidity-independent and as such can be identified with the pedestal; while the other displays rather strong rapidity dependence. The pedestal contribution and the rapidity-dependent contribution at large rapidity separation between the two quarks result in the negative same charge correlations, while at small rapidity separation the second contribution changes sign. We argue that the computed initial state correlations might be partially responsible for the experimentally observed signal in proton-nucleus collisions.

B*Bπ coupling using relativistic heavy quarks

DOE PAGES

Flynn, J. M.; Fritzsch, P.; Kawanai, T.; ...

2016-01-27

We report on a calculation of the B*Bπ coupling in lattice QCD. The strong matrix element (Bπ|B*) is directly related to the leading order low-energy constant in heavy meson chiral perturbation theory (HM ΧPT) for B mesons. We carry out our calculation directly at the b-quark mass using a non-perturbatively tuned clover action that controls discretization effects of order |p →a| and (ma) n for all n. Our analysis is performed on RBC/UKQCD gauge configurations using domain-wall fermions and the Iwasaki gauge action at two lattice spacings of a –1 = 1.729(25) GeV, a –1 = 2.281 (28) GeV, andmore » unitary pion masses down to 290 MeV. We achieve good statistical precision and control all systematic uncertainties, giving a final result for the HM ΧPT coupling g b = 0.56(3) stat(7) sys in the continuum and at the physical light-quark masses. Furthermore, this is the first calculation performed directly at the physical b-quark mass and lies in the region one would expect from carrying out an interpolation between previous results at the charm mass and at the static point.« less

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

NASA Astrophysics Data System (ADS)

Kanazawa, Takuya; Kieburg, Mario

2018-06-01

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

Leading Twist GPDs and Transverse Spin Densities in a Proton

NASA Astrophysics Data System (ADS)

Mondal, Chandan; Maji, Tanmay; Chakrabarti, Dipankar; Zhao, Xingbo

2018-05-01

We present a study of both chirally even and odd generalized parton distributions in the leading twist for the quarks in a proton using the light-front wavefunctions of a quark-diquark model predicted by the holographic QCD. For transversely polarized proton, both chiral even and chiral odd GPDs contribute to the spin densities which are related to the GPDs in transverse impact parameter space. Here, we also present a study of the spin densities for transversely polarized quark and proton.

Nuclear matter from effective quark-quark interaction.

PubMed

Baldo, M; Fukukawa, K

2014-12-12

We study neutron matter and symmetric nuclear matter with the quark-meson model for the two-nucleon interaction. The Bethe-Bruckner-Goldstone many-body theory is used to describe the correlations up to the three hole-line approximation with no extra parameters. At variance with other nonrelativistic realistic interactions, the three hole-line contribution turns out to be non-negligible and to have a substantial saturation effect. The saturation point of nuclear matter, the compressibility, the symmetry energy, and its slope are within the phenomenological constraints. Since the interaction also reproduces fairly well the properties of the three-nucleon system, these results indicate that the explicit introduction of the quark degrees of freedom within the considered constituent quark model is expected to reduce the role of three-body forces.

Leading Twist TMDs in a Light-Front Quark-Diquark Model for Proton

NASA Astrophysics Data System (ADS)

Maji, Tanmay; Chakrabarti, Dipankar

2018-05-01

We present p_{\\perp } variation (fixed x) of the leading-twist T-even transverse momentum dependent parton distributions (TMDs) of a proton in a light-front quark-diquark model at μ ^2=2.4 and 20 GeV^2. The quark densities for unpolarized and transversely polarized proton are also presented. We observe a Soffer bound for TMDs in this model.

Top quark forward-backward asymmetry and same-sign top quark pairs.

PubMed

Berger, Edmond L; Cao, Qing-Hong; Chen, Chuan-Ren; Li, Chong Sheng; Zhang, Hao

2011-05-20

The top quark forward-backward asymmetry measured at the Tevatron collider shows a large deviation from standard model expectations. Among possible interpretations, a nonuniversal Z' model is of particular interest as it naturally predicts a top quark in the forward region of large rapidity. To reproduce the size of the asymmetry, the couplings of the Z' to standard model quarks must be large, inevitably leading to copious production of same-sign top quark pairs at the energies of the Large Hadron Collider (LHC). We explore the discovery potential for tt and ttj production in early LHC experiments at 7-8 TeV and conclude that if no tt signal is observed with 1 fb⁻¹ of integrated luminosity, then a nonuniversal Z' alone cannot explain the Tevatron forward-backward asymmetry.

Chiralities of spiral waves and their transitions.

PubMed

Pan, Jun-ting; Cai, Mei-chun; Li, Bing-wei; Zhang, Hong

2013-06-01

The chiralities of spiral waves usually refer to their rotation directions (the turning orientations of the spiral temporal movements as time elapses) and their curl directions (the winding orientations of the spiral spatial geometrical structures themselves). Traditionally, they are the same as each other. Namely, they are both clockwise or both counterclockwise. Moreover, the chiralities are determined by the topological charges of spiral waves, and thus they are conserved quantities. After the inwardly propagating spirals were experimentally observed, the relationship between the chiralities and the one between the chiralities and the topological charges are no longer preserved. The chiralities thus become more complex than ever before. As a result, there is now a desire to further study them. In this paper, the chiralities and their transition properties for all kinds of spiral waves are systemically studied in the framework of the complex Ginzburg-Landau equation, and the general relationships both between the chiralities and between the chiralities and the topological charges are obtained. The investigation of some other models, such as the FitzHugh-Nagumo model, the nonuniform Oregonator model, the modified standard model, etc., is also discussed for comparison.

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

PubMed

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

2017-11-01

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

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

PubMed Central

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

2017-01-01

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

Disconnected-Sea Quarks Contribution to Nucleon Electromagnetic Form Factors

NASA Astrophysics Data System (ADS)

Sufian, Raza Sabbir

We present comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon electric and magnetic form factors. The lattice QCD estimates of strange quark magnetic moment GsM (0) = -0.064(14)(09) microN and the mean squared charge radius E = -0.0043(16)(14) fm2 are more precise than any existing experimental measurements and other lattice calculations. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in a global fit to calculate results in the continuum limit. We find that the combined light-sea and strange quarks contribution to the nucleon magnetic moment is -0.022(11)(09) microN and to the nucleon mean square charge radius is -0.019(05)(05) fm 2. The most important outcome of this lattice QCD calculation is that while the combined light-sea and strange quarks contribution to the nucleon magnetic moment is small at about 1%, a negative 2.5(9)% contribution to the proton charge radius and a relatively larger positive 16.3(6.1)% contribution to the neutron charge radius come from the sea quarks in the nucleon. For the first time, by performing global fits, we also give predictions of the light-sea and strange quarks contributions to the nucleon electric and magnetic form factors at the physical point and in the continuum and infinite volume limits in the momentum transfer range of 0 ≤ Q2 ≤ 0.5 GeV2.

Results on top-quark physics and top-quark-like signatures by CMS

NASA Astrophysics Data System (ADS)

Chabert, Eric; CMS Collaboration

2017-07-01

This report reviews the results obtained by the CMS Collaboration on top quark physics, focusing on the latest ones based on p-p collisions provided by the LHC at \\sqrt{s}=13{{TeV}} during Run II. It covers measurements of single-top, top quark pairs and associated productions as well as measurements of top quark properties. Finally several beyond the standard model searches involving top quark in the final states are presented, such as searches for supersymmetry in the third generation, heavy resonances decaying into a top quark pair, or dark matter produced in association to a single-top or a top quark pair.

Two-flavor hybrid stars with the Dyson-Schwinger quark model

NASA Astrophysics Data System (ADS)

Wei, J. B.; Chen, H.; Schulze, H.-J.

2017-11-01

We study the properties of two-flavor quark matter in the Dyson-Schwinger model and investigate the possible consequences for hybrid neutron stars, with particular regard to the two-solar-mass limit. We find that with some extreme values of the model parameters, the mass fraction of two-flavor quark matter in heavy neutron stars can be as high as 30 percent and the possible energy release during the conversion from nucleonic neutron stars to hybrid stars can reach 1052 erg. Supported by NSFC (11305144, 11475149, 11303023), Central Universities (CUGL 140609) in China, “NewCompStar,” COST Action MP1304

The phi-meson and Chiral-mass-meson production in heavy-ion collisions as potential probes of quark-gluon-plasma and Chiral symmetry transitions

NASA Technical Reports Server (NTRS)

Takahashi, Y.; Eby, P. B.

1985-01-01

Possibilities of observing abundances of phi mesons and narrow hadronic pairs, as results of QGP and Chiral transitions, are considered for nucleus-nucleus interactions. Kinematical requirements in forming close pairs are satisfied in K+K decays of S(975) and delta (980) mesons with small phi, and phi (91020) mesons with large PT, and in pi-pi decays of familiar resonance mesons only in a partially restored chiral symmetry. Gluon-gluon dominance in QGP can enhance phi meson production. High hadronization rates of primordial resonance mesons which form narrow hadronic pairs are not implausible. Past cosmic ray evidences of anomalous phi production and narrow pair abundances are considered.

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

Pisarski, Robert D.; Skokov, Vladimir V.

Previously, a matrix model of the region near the transition temperature, in the “semi”quark gluon plasma, was developed for the theory of SU(3) gluons without quarks. In this paper we develop a chiral matrix model applicable to QCD by including dynamical quarks with 2+1 flavors. This requires adding a nonet of scalar fields, with both parities, and coupling these to quarks through a Yukawa coupling, y. Treating the scalar fields in mean field approximation, the effective Lagrangian is computed by integrating out quarks to one loop order. As is standard, the potential for the scalar fields is chosen to bemore » symmetric under the flavor symmetry of SU (3) L × SU(3) R × Z (3) A , except for a term linear in the current quark mass, m qk . In addition, at a nonzero temperature T it is necessary to add a new term, ~ m qk T 2 . The parameters of the gluon part of the matrix model are identical to those for the pure glue theory without quarks. The parameters in the chiral matrix model are fixed by the values, at zero temperature, of the pion decay constant and the masses of the pions, kaons, η , and η' . The temperature for the chiral crossover at T$χ$ = 155 MeV is determined by adjusting the Yukawa coupling y . We find reasonable agreement with the results of numerical simulations on the lattice for the pressure and related quantities. In the chiral limit, besides the divergence in the chiral susceptibility there is also a milder divergence in the susceptibility between the Polyakov loop and the chiral order parameter, with critical exponent β $-$ 1 . We compute derivatives with respect to a quark chemical potential to determine the susceptibilities for baryon number, the $χ$ 2n . Especially sensitive tests are provided by $χ$ 4 $-$ $χ$ 2 and by $χ$ 6 , which changes in sign about T$χ$ . In conclusion, the behavior of the susceptibilities in the chiral matrix model strongly suggests that as the temperature increases from T$χ$ , that the transition to

Initial state q q g correlations as a background for the chiral magnetic effect in collision of small systems

DOE PAGES

Kovner, Alex; Lublinsky, Michael; Skokov, Vladimir

2017-11-13

Motivated by understanding the background to chiral magnetic effect in proton-nucleus collisions from first principles, we compute the three particle correlation in the projectile wave function. We extract the correlations between two quarks and one gluon in the framework of the color glass condensate. This is related to the same-charge correlation of the conventional observable for the chiral magnetic effect. We show that there are two different contributions to this correlation function. One contribution is rapidity-independent and as such can be identified with the pedestal; while the other displays rather strong rapidity dependence. The pedestal contribution and the rapidity-dependent contributionmore » at large rapidity separation between the two quarks result in the negative same charge correlations, while at small rapidity separation the second contribution changes sign. We argue that the computed initial state correlations might be partially responsible for the experimentally observed signal in proton-nucleus collisions.« less

Initial state q q g correlations as a background for the chiral magnetic effect in collision of small systems

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

Kovner, Alex; Lublinsky, Michael; Skokov, Vladimir

Motivated by understanding the background to chiral magnetic effect in proton-nucleus collisions from first principles, we compute the three particle correlation in the projectile wave function. We extract the correlations between two quarks and one gluon in the framework of the color glass condensate. This is related to the same-charge correlation of the conventional observable for the chiral magnetic effect. We show that there are two different contributions to this correlation function. One contribution is rapidity-independent and as such can be identified with the pedestal; while the other displays rather strong rapidity dependence. The pedestal contribution and the rapidity-dependent contributionmore » at large rapidity separation between the two quarks result in the negative same charge correlations, while at small rapidity separation the second contribution changes sign. We argue that the computed initial state correlations might be partially responsible for the experimentally observed signal in proton-nucleus collisions.« less

Strong-field control and enhancement of chiral response in bi-elliptical high-order harmonic generation: an analytical model

NASA Astrophysics Data System (ADS)

Ayuso, David; Decleva, Piero; Patchkovskii, Serguei; Smirnova, Olga

2018-06-01

The generation of high-order harmonics in a medium of chiral molecules driven by intense bi-elliptical laser fields can lead to strong chiroptical response in a broad range of harmonic numbers and ellipticities (Ayuso et al 2018 J. Phys. B: At. Mol. Opt. Phys. 51 06LT01). Here we present a comprehensive analytical model that can describe the most relevant features arising in the high-order harmonic spectra of chiral molecules driven by strong bi-elliptical fields. Our model recovers the physical picture underlying chiral high-order harmonic generation (HHG) based on ultrafast chiral hole motion and identifies the rotationally invariant molecular pseudoscalars responsible for chiral dynamics. Using the chiral molecule propylene oxide as an example, we show that one can control and enhance the chiral response in bi-elliptical HHG by tailoring the driving field, in particular by tuning its frequency, intensity and ellipticity, exploiting a suppression mechanism of achiral background based on the linear Stark effect.

The effective chiral Lagrangian from the theta term

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

Mereghetti, E., E-mail: emanuele@physics.arizona.ed; Hockings, W.H., E-mail: whockings@bmc.ed; Kolck, U. van, E-mail: vankolck@physics.arizona.ed

2010-11-15

We construct the effective chiral Lagrangian involving hadronic and electromagnetic interactions originating from the QCD {theta}-bar term. We impose vacuum alignment at both quark and hadronic levels, including field redefinitions to eliminate pion tadpoles. We show that leading time-reversal-violating (TV) hadronic interactions are related to isospin-violating interactions that can in principle be determined from charge-symmetry-breaking experiments. We discuss the complications that arise from TV electromagnetic interactions. Some implications of the expected sizes of various pion-nucleon TV interactions are presented, and the pion-nucleon form factor is used as an example.

A experimental research program on chirality at the LHC

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

Markert, Christina

Heavy-ion collisions provide a unique opportunity to investigate the fundamental laws of physics of the strong force. The extreme conditions created by the collisions within a finite volume are akin to the properties of the deconfined partonic state which existed very shortly after the Big Bang and just prior to visible matter formation in the Universe. In this state massless quarks and gluons (partons) are ``quasi free" particles, the so-called Quark Gluon Plasma (QGP). By following the expansion and cooling of this state, we will map out the process of nucleonic matter formation, which occurs during the phase transition. Themore » fundamental properties of this early partonic phase of matter are not well understood, but they are essential for confirming QCD (Quantum Chromo-Dynamics) and the Standard Model. The specific topic, chiral symmetry restoration, has been called ``the remaining puzzle of QCD.'' This puzzle can only be studied in the dense partonic medium generated in heavy-ion collisions. The research objectives of this proposal are the development and application of new analysis strategies to study chirality and the properties of the medium above the QGP phase transition using hadronic resonances detected with the ALICE experiment at the Large Hadron Collider (LHC) at the CERN research laboratory in Switzerland. This grant funded a new effort at the University of Texas at Austin (UT Austin) to investigate the Quark Gluon Plasma (QGP) at the highest possible energy of 2.76 TeV per nucleon at the Large Hadron Collider (LHC) at CERN via the ALICE experiment. The findings added to our knowledge of the dynamical evolution and the properties of the hot, dense matter produced in heavy-ion collisions, and provided a deeper understanding of multi-hadron interactions in these extreme nuclear matter systems. Our group contributed as well to the hardware and software for the ALICE USA-funded Calorimeter Detector (EMCal). The LHC research program and its connection

Staggered chiral perturbation theory at next-to-leading order

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

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

2005-06-01

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

Chiral symmetry restoration at finite temperature and chemical potential in the improved ladder approximation

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

Taniguchi, Y.; Yoshida, Y.

1997-02-01

The chiral symmetry of QCD is studied at finite temperature and chemical potential using the Schwinger-Dyson equation in the improved ladder approximation. We calculate three order parameters: the vacuum expectation value of the quark bilinear operator, the pion decay constant, and the quark mass gap. We have a second order phase transition at the temperature T{sub c}=169 MeV along the zero chemical potential line, and a first order phase transition at the chemical potential {mu}{sub c}=598 MeV along the zero temperature line. We also calculate the critical exponents of the three order parameters. {copyright} {ital 1997} {ital The American Physicalmore » Society}« less

Baryon chiral perturbation theory extended beyond the low-energy region.

PubMed

Epelbaum, E; Gegelia, J; Meißner, Ulf-G; Yao, De-Liang

We consider an extension of the one-nucleon sector of baryon chiral perturbation theory beyond the low-energy region. The applicability of this approach for higher energies is restricted to small scattering angles, i.e. the kinematical region, where the quark structure of hadrons cannot be resolved. The main idea is to re-arrange the low-energy effective Lagrangian according to a new power counting and to exploit the freedom of the choice of the renormalization condition for loop diagrams. We generalize the extended on-mass-shell scheme for the one-nucleon sector of baryon chiral perturbation theory by choosing a sliding scale, that is, we expand the physical amplitudes around kinematical points beyond the threshold. This requires the introduction of complex-valued renormalized coupling constants, which can be either extracted from experimental data, or calculated using the renormalization group evolution of coupling constants fixed in threshold region.

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

DOE PAGES

Yin, Yi; Liao, Jinfeng

2016-03-03

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

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

PubMed

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

2014-08-14

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

Chirality-controlled crystallization via screw dislocations.

PubMed

Sung, Baeckkyoung; de la Cotte, Alexis; Grelet, Eric

2018-04-11

Chirality plays an important role in science from enantiomeric separation in chemistry to chiral plasmonics in nanotechnology. However, the understanding of chirality amplification from chiral building blocks to ordered helical superstructures remains a challenge. Here, we demonstrate that topological defects, such as screw dislocations, can drive the chirality transfer from particle to supramolecular structure level during the crystallization process. By using a model system of chiral particles, which enables direct imaging of single particle incorporation into growing crystals, we show that the crystallization kinetic pathway is the key parameter for monitoring, via the defects, the chirality amplification of the crystalline structures from racemic to predominantly homohelical. We provide an explanation based on the interplay between geometrical frustration, racemization induced by thermal fluctuations, and particle chirality. Our results demonstrate that screw dislocations not only promote the growth, but also control the chiral morphology and therefore the functionality of crystalline states.

SU(3) sextet model with Wilson fermions

NASA Astrophysics Data System (ADS)

Hansen, Martin; Pica, Claudio

2018-03-01

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

Induction of Chirality in Two-Dimensional Nanomaterials: Chiral 2D MoS2 Nanostructures.

PubMed

Purcell-Milton, Finn; McKenna, Robert; Brennan, Lorcan J; Cullen, Conor P; Guillemeney, Lilian; Tepliakov, Nikita V; Baimuratov, Anvar S; Rukhlenko, Ivan D; Perova, Tatiana S; Duesberg, Georg S; Baranov, Alexander V; Fedorov, Anatoly V; Gun'ko, Yurii K

2018-02-27

Two-dimensional (2D) nanomaterials have been intensively investigated due to their interesting properties and range of potential applications. Although most research has focused on graphene, atomic layered transition metal dichalcogenides (TMDs) and particularly MoS 2 have gathered much deserved attention recently. Here, we report the induction of chirality into 2D chiral nanomaterials by carrying out liquid exfoliation of MoS 2 in the presence of chiral ligands (cysteine and penicillamine) in water. This processing resulted in exfoliated chiral 2D MoS 2 nanosheets showing strong circular dichroism signals, which were far past the onset of the original chiral ligand signals. Using theoretical modeling, we demonstrated that the chiral nature of MoS 2 nanosheets is related to the presence of chiral ligands causing preferential folding of the MoS 2 sheets. There was an excellent match between the theoretically calculated and experimental spectra. We believe that, due to their high aspect ratio planar morphology, chiral 2D nanomaterials could offer great opportunities for the development of chiroptical sensors, materials, and devices for valleytronics and other potential applications. In addition, chirality plays a key role in many chemical and biological systems, with chiral molecules and materials critical for the further development of biopharmaceuticals and fine chemicals, and this research therefore should have a strong impact on relevant areas of science and technology such as nanobiotechnology, nanomedicine, and nanotoxicology.

Enantioselective Biotransformation of Chiral Persistent Organic Pollutants.

PubMed

Zhang, Ying; Ye, Jing; Liu, Min

2017-01-01

Enantiomers of chiral compounds commonly undergo enantioselective transformation in most biologically mediated processes. As chiral persistent organic pollutants (POPs) are extensively distributed in the environment, differences between enantiomers in biotransformation should be carefully considered to obtain exact enrichment and specific health risks. This review provides an overview of in vivo biotransformation of chiral POPs currently indicated in the Stockholm Convention and their chiral metabolites. Peer-reviewed journal articles focused on the research question were thoroughly searched. A set of inclusion and exclusion criteria were developed to identify relevant studies. We mainly compared the results from different animal models under controlled laboratory conditions to show the difference between enantiomers in terms of distinct transformation potential. Interactions with enzymes involved in enantioselective biotransformation, especially cytochrome P450 (CYP), were discussed. Further research areas regarding this issue were proposed. Limited evidence for a few POPs has been found in 30 studies. Enantioselective biotransformation of α-hexachlorocyclohexane (α-HCH), chlordane, dichlorodiphenyltrichloroethane (DDT), heptachlor, hexabromocyclododecane (HBCD), polychlorinated biphenyls (PCBs), and toxaphene, has been investigated using laboratory mammal, fish, bird, and worm models. Tissue and excreta distributions, as well as bioaccumulation and elimination kinetics after administration of racemate and pure enantiomers, have been analyzed in these studies. Changes in enantiomeric fractions have been considered as an indicator of enantioselective biotransformation of chiral POPs in most studies. Results of different laboratory animal models revealed that chiral POP biotransformation is seriously affected by chirality. Pronounced results of species-, tissue-, gender-, and individual-dependent differences are observed in in vivo biotransformation of chiral POPs

Chiral Separations

NASA Astrophysics Data System (ADS)

Stalcup, A. M.

2010-07-01

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

Electromagnetic Coupling of Negative Parity Nucleon Resonances N (1535) Based on Nonrelativistic Constituent Quark Model

NASA Astrophysics Data System (ADS)

Parsaei, Sara; Rajabi, Ali Akbar

2018-01-01

The electromagnetic transition between the nucleon and excited baryons has long been recognized as an important source of information for understanding strong interactions in the domain of quark confinement. We study the electromagnetic properties of the excitation of the negative parity the N*(1535) resonances in the nonrelativistic constituent quark model at large momentum transfers and have performed a calculation the longitudinal and transverse helicity amplitudes. Since the helicity amplitudes depend strongly on the quark wave function in this paper, we consider the baryon as a simple, non-relativistically three-body quark model and also consider a hypercentral potential scheme for the internal baryon structure, which makes three-body forces among three quarks. Since the hyper central potential depends only on the hyper radius, therefore, the Cornell potential which is a combination of the Coulombic-like term plus a linear confining term is considered as the potential for interaction between quarks. In our work, in solving the Schrodinger equation with the Cornell potential, the Nikiforov-Uvarov method employed, and the analytic eigen-energies and eigen-functions obtained. By using the obtained eigen-functions, the transition amplitudes calculated. We show that our results in the range {{{Q}}}2> 2 {{GeV}}2 lead to an overall better agreement with the experimental data in comparison with the other three non-relativistic quark models.

Hyperon stars in a modified quark meson coupling model

NASA Astrophysics Data System (ADS)

Mishra, R. N.; Sahoo, H. S.; Panda, P. K.; Barik, N.; Frederico, T.

2016-09-01

We determine the equation of state (EOS) of nuclear matter with the inclusion of hyperons in a self-consistent manner by using a modified quark meson coupling model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to σ ,ω , and ρ mesons through mean-field approximations. The effect of a nonlinear ω -ρ term on the EOS is studied. The hyperon couplings are fixed from the optical potential values and the mass-radius curve is determined satisfying the maximum mass constraint of 2 M⊙ for neutron stars, as determined in recent measurements of the pulsar PSR J0348+0432. We also observe that there is no significant advantage of introducing the nonlinear ω -ρ term in the context of obtaining the star mass constraint in the present set of parametrizations.

Horava-Lifshitz cosmology, entropic interpretation and quark-hadron phase transition

NASA Astrophysics Data System (ADS)

Kheyri, F.; Khodadi, M.; Sepangi, Hamid Reza

2013-05-01

Based on the assumptions of the standard model of cosmology, a phase transition associated with chiral symmetry breaking after the electroweak transition has occurred at approximately 10 μs after the Big Bang to convert a plasma of free quarks and gluons into hadrons. We consider such a phase transition in the context of a deformed Horava-Lifshitz cosmology. The Friedmann equation for the deformed Horava-Lifshitz universe is obtained using the entropic interpretation of gravity, proposed by Verlinde. We investigate the effects of the parameter ω appearing in the theory on the evolution of the physical quantities relevant to a description of the early universe, namely, the energy density and temperature before, during and after the phase transition. Finally, we study the cross-over phase transition in both high and low temperature regions in view of the recent lattice QCD simulations data.

Maltodextrins as chiral selectors in CE: molecular structure effect of basic chiral compounds on the enantioseparation.

PubMed

Tabani, Hadi; Fakhari, Ali Reza; Nojavan, Saeed

2014-10-01

Prediction of chiral separation for a compound using a chiral selector is an interesting and debatable work. For this purpose, in this study 23 chiral basic drugs with different chemical structures were selected as model solutes and the influence of their chemical structures on the enantioseparation in the presence of maltodextrin (MD) as chiral selector was investigated. For chiral separation, a 100-mM phosphate buffer solution (pH 3.0) containing 10% (w/v) MD with dextrose equivalent (DE) of 4-7 as chiral selector at the temperature of 25°C and voltage of 20 kV was used. Under this condition, baseline separation was achieved for nine chiral compounds and partial separation was obtained for another six chiral compounds while no enantioseparation was obtained for the remaining eight compounds. The results showed that the existence of at least two aromatic rings or cycloalkanes and an oxygen or nitrogen atom or -CN group directly bonded to the chiral center are necessary for baseline separation. With the obtained results in this study, chiral separation of a chiral compound can be estimated with MD-modified capillary electrophoresis before analysis. This prediction will minimize the number of preliminary experiments required to resolve enantiomers and will save time and cost. © 2014 Wiley Periodicals, Inc.

QCD phase diagram using PNJL model with eight-quark interactions

NASA Astrophysics Data System (ADS)

Deb, Paramita; Bhattacharyya, Abhijit; Ghosh, Sanjay K.; Ray, Rajarshi; Lahiri, Anirban

2011-07-01

We present the phase diagram and the fluctuations of different conserved charges like quark number, charge and strangeness at vanishing chemical potential for the 2+1 flavor Polyakov Loop extended Nambu-Jona-Lasinio model with eight-quark interaction terms using three-momentum cutoff regularisation. The main effect of the higher order interaction term is to shift the critical end point to the lower value of the chemical potential and higher value of the temperature. The fluctuations show good qualitative agreement with the lattice data.

Fluctuation instability of the Dirac Sea in quark models of strong interactions

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

Zinovjev, G. M., E-mail: Gennady.Zinovjev@cern.ch; Molodtsov, S. V.

A number of exactly integrable (quark) models of quantum field theory that feature an infinite correlation length are considered. An instability of the standard vacuum quark ensemble, a Dirac sea (in spacetimes of dimension higher than three), is highlighted. It is due to a strong ground-state degeneracy, which, in turn, stems from a special character of the energy distribution. In the case where the momentumcutoff parameter tends to infinity, this distribution becomes infinitely narrow and leads to large (unlimited) fluctuations. A comparison of the results for various vacuum ensembles, including a Dirac sea, a neutral ensemble, a color superconductor, andmore » a Bardeen–Cooper–Schrieffer (BCS) state, was performed. In the presence of color quark interaction, a BCS state is unambiguously chosen as the ground state of the quark ensemble.« less

Fluctuation instability of the Dirac Sea in quark models of strong interactions

NASA Astrophysics Data System (ADS)

Zinovjev, G. M.; Molodtsov, S. V.

2016-03-01

A number of exactly integrable (quark) models of quantum field theory that feature an infinite correlation length are considered. An instability of the standard vacuum quark ensemble, a Dirac sea (in spacetimes of dimension higher than three), is highlighted. It is due to a strong ground-state degeneracy, which, in turn, stems from a special character of the energy distribution. In the case where the momentumcutoff parameter tends to infinity, this distribution becomes infinitely narrow and leads to large (unlimited) fluctuations. A comparison of the results for various vacuum ensembles, including a Dirac sea, a neutral ensemble, a color superconductor, and a Bardeen-Cooper-Schrieffer (BCS) state, was performed. In the presence of color quark interaction, a BCS state is unambiguously chosen as the ground state of the quark ensemble.

Tetraquarks with colour-blind forces in chiral quark models

NASA Astrophysics Data System (ADS)

Pepin, S.; Stancu, Fl.; Genovese, M.; Richard, J.-M.

1997-02-01

We discuss the stability of multiquark systems within the recent model of Glozman et al. where the chromomagnetic hyperfine interaction is replaced by pseudoscalar-meson exchange contributions. We find that such an interaction binds a heavy tetraquark systems QQqq (Q = c, b and q = u, d) by 0.2-0.4 GeV. This is at variance with results of previous models where ccqq is unstable.

Probing composite models at the LHC with exotic quarks production

NASA Astrophysics Data System (ADS)

Kukla, Romain

2017-03-01

After the Higgs boson hunt, the LHC could be a powerful tool to unravel the mystery of which physics lies beyond the realm of the Standard Model. Different new sectors have been postulated to address naturalness: SUSY, extra dimensions and strong dynamics theories. Composite models extend EWSB to a global symmetry breaking whose pseudo-Goldstone boson is the SM Higgs boson. The resulting mass spectrum originates from a partial mixing between fundamental fermions and composite fields which creates massive states including new heavy quarks coupled preferentially to the top quark. Searches for these top partners have been carried out by the ATLAS and CMS collaborations, constraining the models. Other composite contributions are expected to enhance the 4-top production, which should be observable in the next years at the LHC.

Describing the strongly interacting quark-gluon plasma through the Friedberg-Lee model

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

Shu Song; Li Jiarong; Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430079

2010-10-15

The Friedberg-Lee (FL) model is studied at finite temperature and density. The soliton solutions of the FL model in the deconfinement phase transition are solved and thoroughly discussed for certain boundary conditions. We indicate that the solitons before and after the deconfinement have different physical meanings: the soliton before deconfinement represents hadrons, while the soliton after the deconfinement represents the bound state of quarks which leads to a strongly interacting quark-gluon plasma phase. The corresponding phase diagram is given.

Consistent parameter fixing in the quark-meson model with vacuum fluctuations

NASA Astrophysics Data System (ADS)

Carignano, Stefano; Buballa, Michael; Elkamhawy, Wael

2016-08-01

We revisit the renormalization prescription for the quark-meson model in an extended mean-field approximation, where vacuum quark fluctuations are included. At a given cutoff scale the model parameters are fixed by fitting vacuum quantities, typically including the sigma-meson mass mσ and the pion decay constant fπ. In most publications the latter is identified with the expectation value of the sigma field, while for mσ the curvature mass is taken. When quark loops are included, this prescription is however inconsistent, and the correct identification involves the renormalized pion decay constant and the sigma pole mass. In the present article we investigate the influence of the parameter-fixing scheme on the phase structure of the model at finite temperature and chemical potential. Despite large differences between the model parameters in the two schemes, we find that in homogeneous matter the effect on the phase diagram is relatively small. For inhomogeneous phases, on the other hand, the choice of the proper renormalization prescription is crucial. In particular, we show that if renormalization effects on the pion decay constant are not considered, the model does not even present a well-defined renormalized limit when the cutoff is sent to infinity.

Micropatterning of cells reveals chiral morphogenesis

PubMed Central

2013-01-01

Invariant left-right (LR) patterning or chirality is critical for embryonic development. The loss or reversal of LR asymmetry is often associated with malformations and disease. Although several theories have been proposed, the exact mechanism of the initiation of the LR symmetry has not yet been fully elucidated. Recently, chirality has been detected within single cells as well as multicellular structures using several in vitro approaches. These studies demonstrated the universality of cell chirality, its dependence on cell phenotype, and the role of physical boundaries. In this review, we discuss the theories for developmental LR asymmetry, compare various in vitro cell chirality model systems, and highlight possible roles of cell chirality in stem cell differentiation. We emphasize that the in vitro cell chirality systems have great promise for helping unveil the nature of chiral morphogenesis in development. PMID:23672821

Quark Physics without Quarks: A Review of Recent Developments in S-Matrix Theory.

ERIC Educational Resources Information Center

Capra, Fritjof

1979-01-01

Reviews the developments in S-matrix theory over the past five years which have made it possible to derive results characteristic of quark models without any need to postulate the existence of physical quarks. In the new approach, the quark patterns emerge as a consequence of combining the general S-matrix principles with the concept of order.…

Chiral liquid crystal colloids

NASA Astrophysics Data System (ADS)

Yuan, Ye; Martinez, Angel; Senyuk, Bohdan; Tasinkevych, Mykola; Smalyukh, Ivan I.

2018-01-01

Colloidal particles disturb the alignment of rod-like molecules of liquid crystals, giving rise to long-range interactions that minimize the free energy of distorted regions. Particle shape and topology are known to guide this self-assembly process. However, how chirality of colloidal inclusions affects these long-range interactions is unclear. Here we study the effects of distortions caused by chiral springs and helices on the colloidal self-organization in a nematic liquid crystal using laser tweezers, particle tracking and optical imaging. We show that chirality of colloidal particles interacts with the nematic elasticity to predefine chiral or racemic colloidal superstructures in nematic colloids. These findings are consistent with numerical modelling based on the minimization of Landau-de Gennes free energy. Our study uncovers the role of chirality in defining the mesoscopic order of liquid crystal colloids, suggesting that this feature may be a potential tool to modulate the global orientated self-organization of these systems.

Role of the strange quark in the rho(770) meson

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

Molina Peralta, Raquel; Guo, Dehua; Hu, B.

2017-03-01

Recently, the GWU lattice group has evaluated high-precision phase-shift data formore » $$\\pi\\pi$$ scattering in the $I = 1$, $J = 1$ channel. Unitary Chiral Perturbation Theory describes these data well around the resonance region and for different pion masses. Moreover, it allows to extrapolate to the physical point and estimate the effect of the missing $$K\\bar{K}$$ channel in the two-flavor lattice calculation. The absence of the strange quark in the lattice data leads to a lower $$\\rho$$ mass, and the analysis with U$$\\chi$$PT shows that the $$K \\bar{K}$$ channel indeed pushes the $$\\pi\\pi$$-scattering phase shift upward, having a surprisingly large effect on the $$\\rho$$-mass. The inelasticity is shown to be compatible with the experimental data. The analysis is then extended to all available two-flavor lattice simulations and similar mass shifts are observed. Chiral extrapolations of $$N_f = 2 + 1$$ lattice simulations for the $$\\rho(770)$$ are also reported.« less

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

The Top Quark, QCD, And New Physics.

DOE R&D Accomplishments Database

Dawson, S.

2002-06-01

The role of the top quark in completing the Standard Model quark sector is reviewed, along with a discussion of production, decay, and theoretical restrictions on the top quark properties. Particular attention is paid to the top quark as a laboratory for perturbative QCD. As examples of the relevance of QCD corrections in the top quark sector, the calculation of e{sup+}e{sup -}+ t{bar t} at next-to-leading-order QCD using the phase space slicing algorithm and the implications of a precision measurement of the top quark mass are discussed in detail. The associated production of a t{bar t} pair and a Higgs boson in either e{sup+}e{sup -} or hadronic collisions is presented at next-to-leading-order QCD and its importance for a measurement of the top quark Yulrawa coupling emphasized. Implications of the heavy top quark mass for model builders are briefly examined, with the minimal supersymmetric Standard Model and topcolor discussed as specific examples.

Model-independent analysis of quark mass matrices

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

Choudhury, D.; Sarkar, U.

1989-06-01

In view of the apparent inconsistency of the Stech, Fritzsch-Stech, and Fritzsch-Shin models and only marginal agreement of the Fritzsch and modified Fritzsch-Stech models with recent data on /ital B//sub /ital d///sup 0/-/bar B/ /sub /ital d///sup 0/ mixing, we analyze the general quark mass matrices for three generations. Phenomenological considerations restrict the range of parameters involved to different sectors. In the present framework, the constraints corresponding to various /ital Ansa/$/ital uml/---/ital tze/ have been discussed.

η→3π: Study of the Dalitz Plot and Extraction of the Quark Mass Ratio Q.

PubMed

Colangelo, Gilberto; Lanz, Stefan; Leutwyler, Heinrich; Passemar, Emilie

2017-01-13

The η→3π amplitude is sensitive to the quark mass difference m_{u}-m_{d} and offers a unique way to determine the quark mass ratio Q^{2}≡(m_{s}^{2}-m_{ud}^{2})/(m_{d}^{2}-m_{u}^{2}) from experiment. We calculate the amplitude dispersively and fit the KLOE Collaboration data on the charged mode, varying the subtraction constants in the range allowed by chiral perturbation theory. The parameter-free predictions obtained for the neutral Dalitz plot and the neutral-to-charged branching ratio are in excellent agreement with experiment. Our representation of the transition amplitude implies Q=22.0±0.7.

Self-consistent Models of Strong Interaction with Chiral Symmetry

DOE R&D Accomplishments Database

Nambu, Y.; Pascual, P.

1963-04-01

Some simple models of (renormalizable) meson-nucleon interaction are examined in which the nucleon mass is entirely due to interaction and the chiral ( gamma {sub 5}) symmetry is "broken'' to become a hidden symmetry. It is found that such a scheme is possible provided that a vector meson is introduced as an elementary field. (auth)

The Discovery of the Top Quark

DOE R&D Accomplishments Database

Sinervo, P.K.

1995-12-01

The top quark and the Higgs boson are the heaviest elementary particles predicted by the standard model. The four lightest quark flavours, the up, down, strange and charm quarks, were well-established by the mid-1970's. The discovery in 1977 of the {Tau} resonances, a new family of massive hadrons, required the introduction of the fifth quark flavour. Experimental and theoretical studies have indicated that this quark also has a heavier partner, the top quark.

On the quantum symmetry of the chiral Ising model

NASA Astrophysics Data System (ADS)

Vecsernyés, Peter

1994-03-01

We introduce the notion of rational Hopf algebras that we think are able to describe the superselection symmetries of rational quantum field theories. As an example we show that a six-dimensional rational Hopf algebra H can reproduce the fusion rules, the conformal weights, the quantum dimensions and the representation of the modular group of the chiral Ising model. H plays the role of the global symmetry algebra of the chiral Ising model in the following sense: (1) a simple field algebra F and a representation π on Hπ of it is given, which contains the c = {1}/{2} unitary representations of the Virasoro algebra as subrepresentations; (2) the embedding U: H → B( Hπ) is such that the observable algebra π( A) - is the invariant subalgebra of B( Hπ) with respect to the left adjoint action of H and U(H) is the commutant of π( A); (3) there exist H-covariant primary fields in B( Hπ), which obey generalized Cuntz algebra properties and intertwine between the inequivalent sectors of the observables.

Chirality in adsorption on solid surfaces.

PubMed

Zaera, Francisco

2017-12-07

In the present review we survey the main advances made in recent years on the understanding of chemical chirality at solid surfaces. Chirality is an important topic, made particularly relevant by the homochiral nature of the biochemistry of life on Earth, and many chiral chemical reactions involve solid surfaces. Here we start our discussion with a description of surface chirality and of the different ways that chirality can be bestowed on solid surfaces. We then expand on the studies carried out to date to understand the adsorption of chiral compounds at a molecular level. We summarize the work published on the adsorption of pure enantiomers, of enantiomeric mixtures, and of prochiral molecules on chiral and achiral model surfaces, especially on well-defined metal single crystals but also on other flat substrates such as highly ordered pyrolytic graphite. Several phenomena are identified, including surface reconstruction and chiral imprinting upon adsorption of chiral agents, and the enhancement or suppression of enantioselectivity seen in some cases upon adsorption of enantiomixtures of chiral compounds. The possibility of enhancing the enantiopurity of adsorbed layers upon the addition of chiral seeds and the so-called "sergeants and soldiers" phenomenon are presented. Examples are provided where the chiral behavior has been associated with either thermodynamic or kinetic driving forces. Two main approaches to the creation of enantioselective surface sites are discussed, namely, via the formation of supramolecular chiral ensembles made out of small chiral adsorbates, and by adsorption of more complex chiral molecules capable of providing suitable chiral environments for reactants by themselves, via the formation of individual adsorbate:modifier adducts on the surface. Finally, a discussion is offered on the additional effects generated by the presence of the liquid phase often required in practical applications such as enantioselective crystallization, chiral

η → 3 π : Study of the Dalitz plot and extraction of the Quark Mass Ratio Q [The decay η → 3 π : Study of the Dalitz plot and extraction of the quark mass ratio Q

DOE PAGES

Colangelo, Gilberto; Lanz, Stefan; Leutwyler, Heinrich; ...

2017-01-09

Themore » $$\\eta\\to 3\\pi$$ amplitude is sensitive to the quark mass difference $$m_u-m_d$$ and offers a unique way to determine the quark mass ratio $$Q^2\\equiv (m_s^2-m_{ud}^2)/(m_d^2-m_u^2)$$ from experiment. We calculate the amplitude dispersively and fit the KLOE data on the charged mode, varying the subtraction constants in the range allowed by chiral perturbation theory. parameter-free predictions obtained for the neutral Dalitz plot and the neutral-to-charged branching ratio are in excellent agreement with experiment. Lastly, our representation of the transition amplitude implies $$Q = 22.0 \\pm 0.7$$.« less

η → 3 π : Study of the Dalitz plot and extraction of the Quark Mass Ratio Q [The decay η → 3 π : Study of the Dalitz plot and extraction of the quark mass ratio Q

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

Colangelo, Gilberto; Lanz, Stefan; Leutwyler, Heinrich

Themore » $$\\eta\\to 3\\pi$$ amplitude is sensitive to the quark mass difference $$m_u-m_d$$ and offers a unique way to determine the quark mass ratio $$Q^2\\equiv (m_s^2-m_{ud}^2)/(m_d^2-m_u^2)$$ from experiment. We calculate the amplitude dispersively and fit the KLOE data on the charged mode, varying the subtraction constants in the range allowed by chiral perturbation theory. parameter-free predictions obtained for the neutral Dalitz plot and the neutral-to-charged branching ratio are in excellent agreement with experiment. Lastly, our representation of the transition amplitude implies $$Q = 22.0 \\pm 0.7$$.« less

Chirality Differentiation by Diffusion in Chiral Nematic Liquid Crystals

NASA Astrophysics Data System (ADS)

Jiang, Jinghua; Yang, Deng-Ke

2017-01-01

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

Measurement of top quark polarisation in t-channel single top quark production

DOE PAGES

Khachatryan, Vardan

2016-04-13

Our first measurement of the top quark spin asymmetry, sensitive to the top quark polarisation, in t-channel single top quark production is presented. It is based on a sample of pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb -1. A high-purity sample of t-channel single top quark events with an isolated muon is selected. Signal and background components are estimated using a fit to data. Furthermore, a differential cross section measurement, corrected for detector effects, of an angular observable sensitive to the top quark polarisation is performed. The differential distribution ismore » used to extract a top quark spin asymmetry of 0.26 ± 0.03 (stat) ± 0.10 (syst), which is compatible with a p-value of 4.6% with the standard model prediction of 0.44.« less

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

PubMed

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

2016-10-13

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

Effect Of Superfluidity And Differential Rotation Of Quark Matter On Magetic Field Evolution in Neutron Star And Black Hole

NASA Astrophysics Data System (ADS)

Aurongzeb, Deeder

2010-11-01

Anomalous X-ray pulsars and soft gamma-ray repeaters reveal that existence of very strong magnetic field(> 10e15G) from neutron stars. It has been estimated that at the core the magnitude can be even higher at the center. Apart from dynamo mechanism it has been shown that color locked ferromagnetic phase [ Phys. Rev. D. 72,114003(2005)] can be a possible origin of magnetic field. In this study, we explore electric charge of strange quark matter and its effect on forming chirality in the quark-gluon plasma. We show that electromagnetic current induced by chiral magnetic effect [(Phys. Rev. D. 78.07033(2008)] can induce differential rotation in super fluid quark-gluon plasma giving additional boost to the magnetic field. The internal phase and current has no effect from external magnetic field originating from active galactic nuclei due to superconducting phase formation which screens the fields due to Meissner effect. We show that differential motion can create high radial electric field at the surface making all radiation highly polarized and directional including thermal radiation. As the electric field strength can be even stronger for a collapsing neutron star, the implication of this study to detect radiation from black holes will also be discussed. The work was partly completed at the University of Texas at austin

Worldline construction of a covariant chiral kinetic theory

DOE PAGES

Mueller, Niklas; Venugopalan, Raju

2017-07-27

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

Worldline construction of a covariant chiral kinetic theory

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

Mueller, Niklas; Venugopalan, Raju

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

Finite Nuclei in the Quark-Meson Coupling Model.

PubMed

Stone, J R; Guichon, P A M; Reinhard, P G; Thomas, A W

2016-03-04

We report the first use of the effective quark-meson coupling (QMC) energy density functional (EDF), derived from a quark model of hadron structure, to study a broad range of ground state properties of even-even nuclei across the periodic table in the nonrelativistic Hartree-Fock+BCS framework. The novelty of the QMC model is that the nuclear medium effects are treated through modification of the internal structure of the nucleon. The density dependence is microscopically derived and the spin-orbit term arises naturally. The QMC EDF depends on a single set of four adjustable parameters having a clear physics basis. When applied to diverse ground state data the QMC EDF already produces, in its present simple form, overall agreement with experiment of a quality comparable to a representative Skyrme EDF. There exist, however, multiple Skyrme parameter sets, frequently tailored to describe selected nuclear phenomena. The QMC EDF set of fewer parameters, derived in this work, is not open to such variation, chosen set being applied, without adjustment, to both the properties of finite nuclei and nuclear matter.

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

NASA Astrophysics Data System (ADS)

Del Zanna, L.; Bucciantini, N.

2018-06-01

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

Electric Conductivity of Hot and Dense Quark Matter in a Magnetic Field with Landau Level Resummation via Kinetic Equations

NASA Astrophysics Data System (ADS)

Fukushima, Kenji; Hidaka, Yoshimasa

2018-04-01

We compute the electric conductivity of quark matter at finite temperature T and a quark chemical potential μ under a magnetic field B beyond the lowest Landau level approximation. The electric conductivity transverse to B is dominated by the Hall conductivity σH. For the longitudinal conductivity σ∥, we need to solve kinetic equations. Then, we numerically find that σ∥ has only a mild dependence on μ and the quark mass mq. Moreover, σ∥ first decreases and then linearly increases as a function of B , leading to an intermediate B region that looks consistent with the experimental signature for the chiral magnetic effect. We also point out that σ∥ at a nonzero B remains within the range of the lattice-QCD estimate at B =0 .

Electric Conductivity of Hot and Dense Quark Matter in a Magnetic Field with Landau Level Resummation via Kinetic Equations.

PubMed

Fukushima, Kenji; Hidaka, Yoshimasa

2018-04-20

We compute the electric conductivity of quark matter at finite temperature T and a quark chemical potential μ under a magnetic field B beyond the lowest Landau level approximation. The electric conductivity transverse to B is dominated by the Hall conductivity σ_{H}. For the longitudinal conductivity σ_{∥}, we need to solve kinetic equations. Then, we numerically find that σ_{∥} has only a mild dependence on μ and the quark mass m_{q}. Moreover, σ_{∥} first decreases and then linearly increases as a function of B, leading to an intermediate B region that looks consistent with the experimental signature for the chiral magnetic effect. We also point out that σ_{∥} at a nonzero B remains within the range of the lattice-QCD estimate at B=0.

Model of Four-Dimensional Sub-Proton Euclidean Space with Real Time for Valence Quarks. Lagrangian Mechanics

NASA Astrophysics Data System (ADS)

Kreymer, E. L.

2018-06-01

The model of Euclidean space with imaginary time used in sub-hadron physics uses only part of it since this part is isomorphic to Minkowski space and has the velocity limit 0 ≤ ||v Ei|| ≤ 1. The model of four-dimensional Euclidean space with real time (E space), in which 0 ≤ ||v E|| ≤ ∞ is investigated. The vectors of this space have E-invariants, equal or analogous to the invariants of Minkowski space. All relations between physical quantities in E-space, after they are mapped into Minkowski space, satisfy the principles of SRT and are Lorentz-invariant, and the velocity of light corresponds to infinite velocity. Results obtained in the model are different from the physical laws in Minkowski space. Thus, from the model of the Lagrangian mechanics of quarks in a centrally symmetric attractive potential it follows that the energy-mass of a quark decreases with increase of the velocity and is equal to zero for v = ∞. This made it possible to establish the conditions of emission and absorption of gluons by quarks. The effect of emission of gluons by high-energy quarks was discovered experimentally significantly earlier. The model describes for the first time the dynamic coupling of the masses of constituent and current quarks and reveals new possibilities in the study of intrahardon space. The classical trajectory of the oscillation of quarks in protons is described.

Chiral perturbation theory and nucleon-pion-state contaminations in lattice QCD

NASA Astrophysics Data System (ADS)

Bär, Oliver

2017-05-01

Multiparticle states with additional pions are expected to be a non-negligible source of excited-state contamination in lattice simulations at the physical point. It is shown that baryon chiral perturbation theory can be employed to calculate the contamination due to two-particle nucleon-pion-states in various nucleon observables. Leading order results are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions (quark momentum fraction, helicity and transversity moment). Taking into account phenomenological results for the charges and moments the impact of the nucleon-pion-states on lattice estimates for these observables can be estimated. The nucleon-pion-state contribution results in an overestimation of all charges and moments obtained with the plateau method. The overestimation is at the 5-10% level for source-sink separations of about 2 fm. The source-sink separations accessible in contemporary lattice simulations are found to be too small for chiral perturbation theory to be directly applicable.

Radical chiral Floquet phases in a periodically driven Kitaev model and beyond

NASA Astrophysics Data System (ADS)

Po, Hoi Chun; Fidkowski, Lukasz; Vishwanath, Ashvin; Potter, Andrew C.

2017-12-01

We theoretically discover a family of nonequilibrium fractional topological phases in which time-periodic driving of a 2D system produces excitations with fractional statistics, and produces chiral quantum channels that propagate a quantized fractional number of qubits along the sample edge during each driving period. These phases share some common features with fractional quantum Hall states, but are sharply distinct dynamical phenomena. Unlike the integer-valued invariant characterizing the equilibrium quantum Hall conductance, these phases are characterized by a dynamical topological invariant that is a square root of a rational number, inspiring the label: radical chiral Floquet phases. We construct solvable models of driven and interacting spin systems with these properties, and identify an unusual bulk-boundary correspondence between the chiral edge dynamics and bulk "anyon time-crystal" order characterized by dynamical transmutation of electric-charge into magnetic-flux excitations in the bulk.

Asymmetric synthesis using chiral-encoded metal

NASA Astrophysics Data System (ADS)

Yutthalekha, Thittaya; Wattanakit, Chularat; Lapeyre, Veronique; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

2016-08-01

The synthesis of chiral compounds is of crucial importance in many areas of society and science, including medicine, biology, chemistry, biotechnology and agriculture. Thus, there is a fundamental interest in developing new approaches for the selective production of enantiomers. Here we report the use of mesoporous metal structures with encoded geometric chiral information for inducing asymmetry in the electrochemical synthesis of mandelic acid as a model molecule. The chiral-encoded mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and the chiral template molecule, perfectly retains the chiral information after removal of the template. Starting from a prochiral compound we demonstrate enantiomeric excess of the (R)-enantiomer when using (R)-imprinted electrodes and vice versa for the (S)-imprinted ones. Moreover, changing the amount of chiral cavities in the material allows tuning the enantioselectivity.

Sea quarks contribution to the nucleon magnetic moment and charge radius at the physical point

NASA Astrophysics Data System (ADS)

Sufian, Raza Sabbir; Yang, Yi-Bo; Liang, Jian; Draper, Terrence; Liu, Keh-Fei; χ QCD Collaboration

2017-12-01

We report a comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon magnetic moment, charge radius, and the electric and magnetic form factors. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We adopt a model-independent extrapolation of the nucleon magnetic moment and the charge radius. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in a global fit to calculate results in the continuum limit. We find that the combined light and strange disconnected-sea quarks contribution to the nucleon magnetic moment is μM(DI )=-0.022 (11 )(09 ) μN and to the nucleon mean square charge radius is ⟨r2⟩E(DI ) =-0.019 (05 )(05 ) fm2 which is about 1 /3 of the difference between the ⟨rp2⟩E of electron-proton scattering and that of a muonic atom and so cannot be ignored in obtaining the proton charge radius in the lattice QCD calculation. The most important outcome of this lattice QCD calculation is that while the combined light-sea and strange quarks contribution to the nucleon magnetic moment is small at about 1%, a negative 2.5(9)% contribution to the proton mean square charge radius and a relatively larger positive 16.3(6.1)% contribution to the neutron mean square charge radius come from the sea quarks in the nucleon. For the first time, by performing global fits, we also give predictions of the light and strange disconnected-sea quarks contributions to the nucleon electric and magnetic form factors at the physical point and in the continuum and infinite volume limits in the momentum transfer range of 0 ≤Q2≤0.5 GeV2 .

SO(32) heterotic line bundle models

NASA Astrophysics Data System (ADS)

Otsuka, Hajime

2018-05-01

We search for the three-generation standard-like and/or Pati-Salam models from the SO(32) heterotic string theory on smooth, quotient complete intersection Calabi-Yau threefolds with multiple line bundles, each with structure group U(1). These models are S- and T-dual to intersecting D-brane models in type IIA string theory. We find that the stable line bundles and Wilson lines lead to the standard model gauge group with an extra U(1) B-L via a Pati-Salam-like symmetry and the obtained spectrum consists of three chiral generations of quarks and leptons, and vector-like particles. Green-Schwarz anomalous U(1) symmetries control not only the Yukawa couplings of the quarks and leptons but also the higher-dimensional operators causing the proton decay.

Strange Quark Matter Status and Prospects

NASA Technical Reports Server (NTRS)

Sandweiss, J.

2004-01-01

The existence of quark states with more than three quarks is allowed in QCD. The stability of such quark matter states has been studied with lattice QCD and phenomenological bag models, but is not well constrained by theory. The addition of strange quarks to the system allows the quarks to be in lower energy states despite the additional mass penalty. There is additional stability from reduced Coulomb repulsion. SQM is expected to have a low Z/A. Stable or metastable massive multiquark states contain u, d, and s quarks.

Kaon B-parameter in mixed action chiral perturbation theory

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

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

2007-02-01

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

Integrability in heavy quark effective theory

NASA Astrophysics Data System (ADS)

Braun, Vladimir M.; Ji, Yao; Manashov, Alexander N.

2018-06-01

It was found that renormalization group equations in the heavy-quark effective theory (HQET) for the operators involving one effective heavy quark and light degrees of freedom are completely integrable in some cases and are related to spin chain models with the Hamiltonian commuting with the nondiagonal entry C( u) of the monodromy matrix. In this work we provide a more complete mathematical treatment of such spin chains in the QISM framework. We also discuss the relation of integrable models that appear in the HQET context with the large-spin limit of integrable models in QCD with light quarks. We find that the conserved charges and the "ground state" wave functions in HQET models can be obtained from the light-quark counterparts in a certain scaling limit.

Novel electrochemical method for the characterization of the degree of chirality in chiral polyaniline.

PubMed

Feng, Zhang; Li, Ma; Yan, Yang; Jihai, Tang; Xiao, Li; Wanglin, Li

2013-01-01

A novel method to indicate the degree of chirality in polyaniline (PANI) was developed. The (D-camphorsulfonic acid)- and (HCl)-PANI-based electrodes exhibited significantly different electrochemical performances in D- and L-Alanine (Ala) aqueous solution, respectively, which can be used for the characterization the optical activity of chiral PANI. Cyclic voltammogram, tafel, and open circuit potential of PANI-based electrodes were measured within D- and L-Ala electrolyte solution, respectively. The open circuit potentials under different reacting conditions were analyzed by Doblhofer model formula, in which [C(+)](poly1)/[C(+)](poly2) was used as a parameter to characterize the degree of chirality in chiral PANI. The results showed that [C(+)](poly1)/[C(+)](poly2) can be increased with increasing concentrations of (1S)-(+)- and (1R)-(-)-10-camphorsulfonic acid. In addition, we detected that appropriate response time and lower temperature are necessary to improve the degree of chirality. Copyright © 2012 Wiley Periodicals, Inc.

Scalar quantum chromodynamics in two dimensions and parton model. [Scalar quarks, SU(N) groups

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

Shei, S.S.; Tsao, H.S.

1977-05-01

The SU(N) scalar quantum chromodynamics in two space-time dimensions in the large N limit are studied. This is the model of color gauge fields interacting with scalar quarks. It is found that the consensual properties of the four dimensional QCD, i.e., the infrared slavery, quark confinement, the charmonium picture etc. are all realized. Moreover, the current in this model mimics nicely the behaviors of current in the four dimensional QCD, in contrast to the original model of 't Hooft.

Chiral superconductors.

PubMed

Kallin, Catherine; Berlinsky, John

2016-05-01

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

Understanding Cooperative Chirality at the Nanoscale

NASA Astrophysics Data System (ADS)

Yu, Shangjie; Wang, Pengpeng; Govorov, Alexander; Ouyang, Min

Controlling chirality of organic and inorganic structures plays a key role in many physical, chemical and biochemical processes, and may offer new opportunity to create technology applications based on chiroptical effect. In this talk, we will present a theoretical model and simulation to demonstrate how to engineer nanoscale chirality in inorganic nanostructures via synergistic control of electromagnetic response of both lattice and geometry, leading to rich tunability of chirality at the nanoscale. Our model has also been applied to understand recent materials advancement of related control with excellent agreement, and can elucidate physical origins of circular dichroism features in the experiment.

Baryon octet electromagnetic form factors in a confining NJL model

NASA Astrophysics Data System (ADS)

Carrillo-Serrano, Manuel E.; Bentz, Wolfgang; Cloët, Ian C.; Thomas, Anthony W.

2016-08-01

Electromagnetic form factors of the baryon octet are studied using a Nambu-Jona-Lasinio model which utilizes the proper-time regularization scheme to simulate aspects of colour confinement. In addition, the model also incorporates corrections to the dressed quarks from vector meson correlations in the t-channel and the pion cloud. Comparison with recent chiral extrapolations of lattice QCD results shows a remarkable level of consistency. For the charge radii we find the surprising result that rEp < rEΣ+ and | rEn | < | rEΞ0 |, whereas the magnetic radii have a pattern largely consistent with a naive expectation based on the dressed quark masses.

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

PubMed

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

2018-05-16

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

Chiral magnetic effect without chirality source in asymmetric Weyl semimetals

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

Light quark masses with overlap fermions in quenched QCD

NASA Astrophysics Data System (ADS)

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

2001-12-01

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

Chiral extrapolation of nucleon axial charge gA in effective field theory

NASA Astrophysics Data System (ADS)

Li, Hong-na; Wang, P.

2016-12-01

The extrapolation of nucleon axial charge gA is investigated within the framework of heavy baryon chiral effective field theory. The intermediate octet and decuplet baryons are included in the one loop calculation. Finite range regularization is applied to improve the convergence in the quark-mass expansion. The lattice data from three different groups are used for the extrapolation. At physical pion mass, the extrapolated gA are all smaller than the experimental value. Supported by National Natural Science Foundation of China (11475186) and Sino-German CRC 110 (NSFC 11621131001)

Chiral topological insulator of magnons

NASA Astrophysics Data System (ADS)

Li, Bo; Kovalev, Alexey A.

2018-05-01

We propose a magnon realization of 3D topological insulator in the AIII (chiral symmetry) topological class. The topological magnon gap opens due to the presence of Dzyaloshinskii-Moriya interactions. The existence of the topological invariant is established by calculating the bulk winding number of the system. Within our model, the surface magnon Dirac cone is protected by the sublattice chiral symmetry. By analyzing the magnon surface modes, we confirm that the backscattering is prohibited. By weakly breaking the chiral symmetry, we observe the magnon Hall response on the surface due to opening of the gap. Finally, we show that by changing certain parameters, the system can be tuned between the chiral topological insulator, three-dimensional magnon anomalous Hall, and Weyl magnon phases.

Baryon Spectroscopy and the Constituent Quark Model

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

A.W. Thomas; R.D. Young

2005-07-26

We explore further the idea that the lattice QCD data for hadron properties in the region m[^2][_pi] > 0.2GeV^2 can be described by the constituent quark model. This leads to a natural explanation of the fact that nucleon excited states are generally stable for pion masses greater than their physical excitation energies. Finally, we apply these same ideas to the problem of how pentaquarks might behave in lattice QCD, with interesting conclusions.

Chirality effect in disordered graphene ribbon junctions

NASA Astrophysics Data System (ADS)

Long, Wen

2012-05-01

We investigate the influence of edge chirality on the electronic transport in clean or disordered graphene ribbon junctions. By using the tight-binding model and the Landauer-Büttiker formalism, the junction conductance is obtained. In the clean sample, the zero-magnetic-field junction conductance is strongly chirality-dependent in both unipolar and bipolar ribbons, whereas the high-magnetic-field conductance is either chirality-independent in the unipolar or chirality-dependent in the bipolar ribbon. Furthermore, we study the disordered sample in the presence of magnetic field and find that the junction conductance is always chirality-insensitive for both unipolar and bipolar ribbons with adequate disorders. In addition, the disorder-induced conductance plateaus can exist in all chiral bipolar ribbons provided the disorder strength is moderate. These results suggest that we can neglect the effect of edge chirality in fabricating electronic devices based on the magnetotransport in a disordered graphene ribbon.

STATIC QUARK ANTI-QUARK FREE AND INTERNAL ENERGY IN 2-FLAVOR QCD AND BOUND STATES IN THE QGP.

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

ZANTOW, F.; KACZMAREK, O.

2005-07-25

We present results on heavy quark free energies in 2-flavour QCD. The temperature dependence of the interaction between static quark anti-quark pairs will be analyzed in terms of temperature dependent screening radii, which give a first estimate on the medium modification of (heavy quark) bound states in the quark gluon plasma. Comparing those radii to the (zero temperature) mean squared charge radii of chasmonium states indicates that the J/{Psi} may survive the phase transition as a bound state, while {chi}{sub c} and {Psi}{prime} are expected to show significant thermal modifications at temperatures close to the transition. Furthermore we will analyzemore » the relation between heavy quark free energies, entropy contributions and internal energy and discuss their relation to potential models used to analyze the melting of heavy quark bound states above the deconfinement temperature. Results of different groups and various potential models for bound states in the deconfined phase of QCD are compared.« less

Stable Pentaquarks from Strange Chiral Multiplets

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

Silas Beane

2004-12-01

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

Disordered two-dimensional electron systems with chiral symmetry

NASA Astrophysics Data System (ADS)

Markoš, P.; Schweitzer, L.

2012-10-01

We review the results of our recent numerical investigations on the electronic properties of disordered two dimensional systems with chiral unitary, chiral orthogonal, and chiral symplectic symmetry. Of particular interest is the behavior of the density of states and the logarithmic scaling of the smallest Lyapunov exponents in the vicinity of the chiral quantum critical point in the band center at E=0. The observed peaks or depressions in the density of states, the distribution of the critical conductances, and the possible non-universality of the critical exponents for certain chiral unitary models are discussed.

Quark flavour observables in the Littlest Higgs model with T-parity after LHC Run 1.

PubMed

Blanke, Monika; Buras, Andrzej J; Recksiegel, Stefan

2016-01-01

The Littlest Higgs model with T-parity (LHT) belongs to the simplest new physics scenarios with new sources of flavour and CP violation. The latter originate in the interactions of ordinary quarks and leptons with heavy mirror quarks and leptons that are mediated by new heavy gauge bosons. Also a heavy fermionic top partner is present in this model which communicates with the SM fermions by means of standard [Formula: see text] and [Formula: see text] gauge bosons. We present a new analysis of quark flavour observables in the LHT model in view of the oncoming flavour precision era. We use all available information on the CKM parameters, lattice QCD input and experimental data on quark flavour observables and corresponding theoretical calculations, taking into account new lower bounds on the symmetry breaking scale and the mirror quark masses from the LHC. We investigate by how much the branching ratios for a number of rare K and B decays are still allowed to depart from their SM values. This includes [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]. Taking into account the constraints from [Formula: see text] processes, significant departures from the SM predictions for [Formula: see text] and [Formula: see text] are possible, while the effects in B decays are much smaller. In particular, the LHT model favours [Formula: see text], which is not supported by the data, and the present anomalies in [Formula: see text] decays cannot be explained in this model. With the recent lattice and large N input the imposition of the [Formula: see text] constraint implies a significant suppression of the branching ratio for [Formula: see text] with respect to its SM value while allowing only for small modifications of [Formula: see text]. Finally, we investigate how the LHT physics could be distinguished from other models by means of indirect measurements and

Influence of Chirality in Ordered Block Copolymer Phases

NASA Astrophysics Data System (ADS)

Prasad, Ishan; Grason, Gregory

2015-03-01

Block copolymers are known to assemble into rich spectrum of ordered phases, with many complex phases driven by asymmetry in copolymer architecture. Despite decades of study, the influence of intrinsic chirality on equilibrium mesophase assembly of block copolymers is not well understood and largely unexplored. Self-consistent field theory has played a major role in prediction of physical properties of polymeric systems. Only recently, a polar orientational self-consistent field (oSCF) approach was adopted to model chiral BCP having a thermodynamic preference for cholesteric ordering in chiral segments. We implement oSCF theory for chiral nematic copolymers, where segment orientations are characterized by quadrupolar chiral interactions, and focus our study on the thermodynamic stability of bi-continuous network morphologies, and the transfer of molecular chirality to mesoscale chirality of networks. Unique photonic properties observed in butterfly wings have been attributed to presence of chiral single-gyroid networks, this has made it an attractive target for chiral metamaterial design.

Nuclear pasta phases within the quark-meson coupling model

NASA Astrophysics Data System (ADS)

Grams, Guilherme; Santos, Alexandre M.; Panda, Prafulla K.; Providência, Constança; Menezes, Débora P.

2017-05-01

In this work, the low-density regions of nuclear and neutron star matter are studied. The search for the existence of nuclear pasta phases in this region is performed within the context of the quark-meson coupling (QMC) model, which incorporates quark degrees of freedom. Fixed proton fractions are considered, as well as nuclear matter in β equilibrium at zero temperature. We discuss the recent attempts to better understand the surface energy in the coexistence phases regime and we present results that show the existence of the pasta phases subject to some choices of the surface energy coefficient. We also analyze the influence of the nuclear pasta on some neutron star properties. The equation of state containing the pasta phase will be part of a complete grid for future use in supernova simulations.

QCD next-to-leading-order predictions matched to parton showers for vector-like quark models.

PubMed

Fuks, Benjamin; Shao, Hua-Sheng

2017-01-01

Vector-like quarks are featured by a wealth of beyond the Standard Model theories and are consequently an important goal of many LHC searches for new physics. Those searches, as well as most related phenomenological studies, however, rely on predictions evaluated at the leading-order accuracy in QCD and consider well-defined simplified benchmark scenarios. Adopting an effective bottom-up approach, we compute next-to-leading-order predictions for vector-like-quark pair production and single production in association with jets, with a weak or with a Higgs boson in a general new physics setup. We additionally compute vector-like-quark contributions to the production of a pair of Standard Model bosons at the same level of accuracy. For all processes under consideration, we focus both on total cross sections and on differential distributions, most these calculations being performed for the first time in our field. As a result, our work paves the way to precise extraction of experimental limits on vector-like quarks thanks to an accurate control of the shapes of the relevant observables and emphasise the extra handles that could be provided by novel vector-like-quark probes never envisaged so far.

Exotic Signals of Vectorlike Quarks

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

Dobrescu, Bogdan A.; Yu, Felix

2016-12-06

Vectorlike fermions are an important target for hadron collider searches. We show that the vectorlike quarks may predominantly decay via higher-dimensional operators into a quark plus a couple of other Standard Model fermions. Pair production of vectorlike quarks of charge 2/3 at the LHC would then lead to a variety of possible final states, includingmore » $$t\\bar t + 4\\tau$$, $$t\\bar b\

Color-Sextet Quark Productions at Hadron Colliders

NASA Astrophysics Data System (ADS)

Tanaka, Hidekazu; Watanabe, Isamu

Production cross-sections of color-sextet quarks at hadron colliders are estimated in various energies and the results are compared with cross-sections of the conventional top quark productions. Particular attentions are paid for a model recently proposed in Ref. 2 in order to explain the dynamical mechanism of the electroweak symmetry breaking. The model may be tested at SSC and LHC if the sextet quarks dominantly decay semileptonically through effective fourfermion interactions, or if the sextet quarks have long enough lifetime to reach the detectors.

SIMP model at NNLO in chiral perturbation theory

NASA Astrophysics Data System (ADS)

Hansen, Martin; Langæble, Kasper; Sannino, Francesco

2015-10-01

We investigate the phenomenological viability of a recently proposed class of composite dark matter models where the relic density is determined by 3 →2 number-changing processes in the dark sector. Here the pions of the strongly interacting field theory constitute the dark matter particles. By performing a consistent next-to-leading- and next-to-next-to-leading-order chiral perturbative investigation we demonstrate that the leading-order analysis cannot be used to draw conclusions about the viability of the model. We further show that higher-order corrections substantially increase the tension with phenomenological constraints challenging the viability of the simplest realization of the strongly interacting massive particle paradigm.

Chiral acidic amino acids induce chiral hierarchical structure in calcium carbonate

PubMed Central

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

2017-01-01

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

Phase structure of completely asymptotically free SU(Nc) models with quarks and scalar quarks

NASA Astrophysics Data System (ADS)

Hansen, F. F.; Janowski, T.; Langæble, K.; Mann, R. B.; Sannino, F.; Steele, T. G.; Wang, Z. W.

2018-03-01

We determine the phase diagram of completely asymptotically free SU (Nc) gauge theories featuring Ns complex scalars and Nf Dirac quarks transforming according to the fundamental representation of the gauge group. The analysis is performed at the maximum known order in perturbation theory. We unveil a very rich dynamics and associated phase structure. Intriguingly, we discover that the completely asymptotically free conditions guarantee that the infrared dynamics displays long-distance conformality, and in a regime when perturbation theory is applicable. We conclude our analysis by determining the quantum corrected potential of the model and summarizing the possible patterns of radiative symmetry breaking. These models are of potential phenomenological interest as either elementary or composite ultraviolet finite extensions of the standard model.

Chiral Magnetic Effect Search in p(d)+Au, Au+Au Collisions at RHIC

NASA Astrophysics Data System (ADS)

Zhao, Jie

The chiral magnetic effect (CME) refers to charge separation along a strong magnetic field of single-handed quarks, caused by interactions with topological gluon fields from QCD vacuum fluctuations. A major background of CME measurements in heavy-ion collisions comes from resonance decays coupled with elliptical flow anisotropy. These proceedings present two new studies from STAR to shed further light on the background issue: (1) small system p+Au and d+Au collisions where the CME signal is not expected, and (2) pair invariant mass dependence where resonance peaks can be identified.

Cooperative expression of atomic chirality in inorganic nanostructures.

PubMed

Wang, Peng-Peng; Yu, Shang-Jie; Govorov, Alexander O; Ouyang, Min

2017-02-02

Cooperative chirality phenomena extensively exist in biomolecular and organic systems via intra- and inter-molecular interactions, but study of inorganic materials has been lacking. Here we report, experimentally and theoretically, cooperative chirality in colloidal cinnabar mercury sulfide nanocrystals that originates from chirality interplay between the crystallographic lattice and geometric morphology at different length scales. A two-step synthetic scheme is developed to allow control of critical parameters of these two types of handedness, resulting in different chiral interplays expressed as observables through materials engineering. Furthermore, we adopt an electromagnetic model with the finite element method to elucidate cooperative chirality in inorganic systems, showing excellent agreement with experimental results. Our study enables an emerging class of nanostructures with tailored cooperative chirality that is vital for fundamental understanding of nanoscale chirality as well as technology applications based on new chiroptical building blocks.

Cooperative expression of atomic chirality in inorganic nanostructures

PubMed Central

Wang, Peng-peng; Yu, Shang-Jie; Govorov, Alexander O; Ouyang, Min

2017-01-01

Cooperative chirality phenomena extensively exist in biomolecular and organic systems via intra- and inter-molecular interactions, but study of inorganic materials has been lacking. Here we report, experimentally and theoretically, cooperative chirality in colloidal cinnabar mercury sulfide nanocrystals that originates from chirality interplay between the crystallographic lattice and geometric morphology at different length scales. A two-step synthetic scheme is developed to allow control of critical parameters of these two types of handedness, resulting in different chiral interplays expressed as observables through materials engineering. Furthermore, we adopt an electromagnetic model with the finite element method to elucidate cooperative chirality in inorganic systems, showing excellent agreement with experimental results. Our study enables an emerging class of nanostructures with tailored cooperative chirality that is vital for fundamental understanding of nanoscale chirality as well as technology applications based on new chiroptical building blocks. PMID:28148957

Baryon octet electromagnetic form factors in a confining NJL model

DOE PAGES

Carrillo-Serrano, Manuel E.; Bentz, Wolfgang; Cloet, Ian C.; ...

2016-05-25

Electromagnetic form factors of the baryon octet are studied using a Nambu–Jona-Lasinio model which utilizes the proper-time regularization scheme to simulate aspects of colour confinement. In addition, the model also incorporates corrections to the dressed quarks from vector meson correlations in the t-channel and the pion cloud. Here, comparison with recent chiral extrapolations of lattice QCD results shows a remarkable level of consistency. For the charge radii we find the surprising result that r p E < r Σ+ E and |r n E| < |r Ξ0 E|, whereas the magnetic radii have a pattern largely consistent with a naivemore » expectation based on the dressed quark masses.« less

The Ξ* and Ωη Interaction Within a Chiral Unitary Approach

NASA Astrophysics Data System (ADS)

Xu, Si-Qi; Xie, Ju-Jun; Chen, Xu-Rong; Jia, Duo-Jie

2016-01-01

In this work we study the interaction of the coupled channels Ωη and {\\Xi}\\ast\\bar{K} within the chiral unitary approach. The systems under consideration have total isospins 0, strangeness S = -3, and spin 3/2. We study the s wave interaction which implies that the possible resonances generated in the system can have spin-parity JP = 3/2-. The unitary amplitudes in coupled channels develop poles that can be associated with some known baryonic resonances. We find there is a dynamically generated 3/2- Ω state with mass around 1800 MeV, which is in agreement with the predictions of the five-quark model. Supported by the National Basic Research Program (973 Program Grant No. 2014CB845406), and the National Natural Science Foundation of China under Grant Nos. 11475227, 11265014, and the Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China No. Y5KF151CJ1

Charm degrees of freedom in the quark gluon plasma

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

Mukherjee, Swagato; Petreczky, Peter; Sharma, Sayantan

2016-01-11

The lattice QCD studies on fluctuations and correlations of charm quantum number have established that deconfinement of charm degrees of freedom sets in around the chiral crossover temperature, T c; i.e., charm degrees of freedom carrying fractional baryonic charge start to appear. When we reexamine those same lattice QCD data we show that, in addition to the contributions from quarklike excitations, the partial pressure of charm degrees of freedom may still contain significant contributions from open-charm-meson- and baryonlike excitations associated with integral baryonic charges for temperatures up to 1.2T c. Finally, charm-quark quasiparticles become the dominant degrees of freedom formore » temperatures T>1.2T c.« less

Scalar flavor changing neutral currents and rare top quark decays in a two Higgs doublet model 'for the top quark'

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

Baum, Itzhak; Physics Department, Technion-Institute of Technology, Haifa 32000; Eilam, Gad

2008-06-01

In the so-called two Higgs doublet model for the top quark (T2HDM), first suggested by Das and Kao, the top quark receives a special status, which endows it with a naturally large mass, and also potentially gives rise to large flavor changing neutral currents only in the up-quark sector. In this paper, we calculate the branching ratio for the rare decays t{yields}ch and h{yields}tc (h is a neutral Higgs scalar) in the T2HDM, at tree level and at 1-loop when it exceeds the tree level. We compare our results to predictions from other versions of 2HDM's and find that themore » scalar flavor changing neutral currents in the T2HDM can play a significant role in these decays. In particular, the 1-loop mediated decays can be significantly enhanced in the T2HDM compared with the 2HDM of types I and II, in some instances reaching BR{approx}10{sup -4}, which is within the detectable level at the LHC.« less

Patterns of symmetry breaking in chiral QCD

NASA Astrophysics Data System (ADS)

Bolognesi, Stefano; Konishi, Kenichi; Shifman, Mikhail

2018-05-01

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

Bayesian truncation errors in chiral effective field theory: model checking and accounting for correlations

NASA Astrophysics Data System (ADS)

Melendez, Jordan; Wesolowski, Sarah; Furnstahl, Dick

2017-09-01

Chiral effective field theory (EFT) predictions are necessarily truncated at some order in the EFT expansion, which induces an error that must be quantified for robust statistical comparisons to experiment. A Bayesian model yields posterior probability distribution functions for these errors based on expectations of naturalness encoded in Bayesian priors and the observed order-by-order convergence pattern of the EFT. As a general example of a statistical approach to truncation errors, the model was applied to chiral EFT for neutron-proton scattering using various semi-local potentials of Epelbaum, Krebs, and Meißner (EKM). Here we discuss how our model can learn correlation information from the data and how to perform Bayesian model checking to validate that the EFT is working as advertised. Supported in part by NSF PHY-1614460 and DOE NUCLEI SciDAC DE-SC0008533.

Chiral Graphene Quantum Dots

DOE PAGES

Suzuki, Nozomu; Wang, Yichun; Elvati, Paolo; ...

2016-01-15

Chiral nanostructures from metals and semiconductors attract wide interest as components for polarization-enabled optoelectronic devices. Similarly to other fields of nanotechnology, graphene-based materials can greatly enrich physical and chemical phenomena associated with optical and electronic properties of chiral nanostructures and facilitate their applications in biology as well as other areas. Here, we report that covalent attachment of l/d-cysteine moieties to the edges of graphene quantum dots (GQDs) leads to their helical buckling due to chiral interactions at the “crowded” edges. Circular dichroism (CD) spectra of the GQDs revealed bands at ca. 210–220 and 250–265 nm that changed their signs formore » different chirality of the cysteine edge ligands. The high-energy chiroptical peaks at 210–220 nm correspond to the hybridized molecular orbitals involving the chiral center of amino acids and atoms of graphene edges. Diverse experimental and modeling data, including density functional theory calculations of CD spectra with probabilistic distribution of GQD isomers, indicate that the band at 250–265 nm originates from the three-dimensional twisting of the graphene sheet and can be attributed to the chiral excitonic transitions. The positive and negative low-energy CD bands correspond to the left and right helicity of GQDs, respectively. Exposure of liver HepG2 cells to l/d-GQDs reveals their general biocompatibility and a noticeable difference in the toxicity of the stereoisomers. Molecular dynamics simulations demonstrated that d-GQDs have a stronger tendency to accumulate within the cellular membrane than l-GQDs. Finally, emergence of nanoscale chirality in GQDs decorated with biomolecules is expected to be a general stereochemical phenomenon for flexible sheets of nanomaterials.« less

Electric line source illumination of a chiral cylinder placed in another chiral background medium

NASA Astrophysics Data System (ADS)

Aslam, M.; Saleem, A.; Awan, Z. A.

2018-05-01

An electric line source illumination of a chiral cylinder embedded in a chiral background medium is considered. The field expressions inside and outside of a chiral cylinder have been derived using the wave field decomposition approach. The effects of various chiral cylinders, chiral background media and source locations upon the scattering gain pattern have been investigated. It is observed that the chiral background reduces the backward scattering gain as compared to the free space background for a dielectric cylinder. It is also studied that by moving a line source away from a cylinder reduces the backward scattering gain for a chiral cylinder placed in a chiral background under some specific conditions. A unique phenomenon of reduced scattering gain has been observed at a specific observation angle for a chiral cylinder placed in a chiral background having an electric line source location of unity free space wavelength. An isotropic scattering gain pattern is observed for a chiral nihility background provided that if cylinder is chiral or chiral nihility type. It is also observed that this isotropic behaviour is independent of background and cylinder chirality.

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

Low-lying 1/2- hidden strange pentaquark states in the constituent quark model

NASA Astrophysics Data System (ADS)

Li, Hui; Wu, Zong-Xiu; An, Chun-Sheng; Chen, Hong

2017-12-01

We investigate the spectrum of the low-lying 1/2- hidden strange pentaquark states, employing the constituent quark model, and looking at two ways within that model of mediating the hyperfine interaction between quarks - Goldstone boson exchange and one gluon exchange. Numerical results show that the lowest 1/2- hidden strange pentaquark state in the Goldstone boson exchange model lies at ˜1570 MeV, so this pentaquark configuration may form a notable component in S 11(1535) if the Goldstone boson exchange model is applied. This is consistent with the prediction that S 11(1535) couples very strongly to strangeness channels. Supported by National Natural Science Foundation of China (11675131, 11645002), Chongqing Natural Science Foundation (cstc2015jcyjA00032) and Fundamental Research Funds for the Central Universities (SWU115020)

Propagation of cosmic rays through the atmosphere in the quark-gluon strings model

NASA Technical Reports Server (NTRS)

Erlykin, A. D.; Krutikova, N. P.; Shabelski, Y. M.

1985-01-01

The quark-gluon strings model succeeds in the description of multiple hadron production in the central rapidity region of nucleon-nucleon interctions. This model was developed for hadron-nucleus interactions and used for calculation of the cosmic ray propagation through the atmosphere. It is shown that at energies 10 to the 11th power to the 12th power eV, this model gives a satisfactory description of experimental data. But with the increase of the energy up to approximately 10 to the 14th power eV, results of calculations and of experiments begin to differ and this difference rises with the energy. It may indicate that the scaling violation in the fragmentation region of inclusive spectra for hadron-nucleus interactions is stronger than in the quark-gluon strings model.

Heisenberg Uncertainty and the Allowable Masses of the Up Quark and Down Quark

NASA Astrophysics Data System (ADS)

Orr, Brian

2004-05-01

A possible explanation for the inability to attain deterministic measurements of an elementary particle's energy, as given by the Heisenberg Uncertainty Principle, manifests itself in an interesting anthropic consequent of Andrei Linde's Self-reproducing Inflationary Multiverse model. In Linde's model, the physical laws and constants that govern our universe adopt other values in other universes, due to variable Higgs fields. While the physics in our universe allow for the advent of life and consciousness, the physics necessary for life are not likely to exist in other universes -- Linde demonstrates this through a kind of Darwinism for universes. Our universe, then, is unique. But what are the physical laws and constants that make our universe what it is? Craig Hogan identifies five physical constants that are not bound by symmetry. Fine-tuning these constants gives rise to the basic behavior and structures of the universe. Three of the non-symmetric constants are fermion masses: the up quark mass, the down quark mass, and the electron mass. I will explore Linde's and Hogan's works by comparing the amount of uncertainty in quark masses, as calculated from the Heisenberg Uncertainty Principle, to the range of quark mass values consistent with our observed universe. Should the fine-tuning of the up quark and down quark masses be greater than the range of Heisenberg uncertainties in their respective masses (as I predict, due to quantum tunneling), then perhaps there is a correlation between the measured Heisenberg uncertainty in quark masses and the fine-tuning of masses required for our universe to be as it is. Hogan; "Why the Universe is Just So;" Reviews of Modern Physics; Issue 4; Vol. 72; pg. 1149-1161; Oct. 2000 Linde, "The Self-Reproducing Inflationary Universe;" Scientific American; No. 5; Vol. 271; pg. 48-55; Nov. 1994

FDTD chiral brain tissue model for specific absorption rate determination under radiation from mobile phones at 900 and 1800 MHz

NASA Astrophysics Data System (ADS)

Zamorano, M.; Torres-Silva, H.

2006-04-01

A new electrodynamics model formed by chiral bioplasma, which represents the human head inner structure and makes it possible to analyse its behaviour when it is irradiated by a microwave electromagnetic field from cellular phones, is presented. The finite-difference time-domain (FDTD) numeric technique is used, which allows simulation of the electromagnetic fields, deduced with Maxwell's equations, and allows us to simulate the specific absorption rate (SAR). The results show the SAR behaviour as a function of the input power and the chirality factor. In considering the chiral brain tissue in the proposed human head model, the two more important conclusions of our work are the following: (a) the absorption of the electromagnetic fields from cellular phones is stronger, so the SAR coefficient is higher than that using the classical model, when values of the chiral factor are of order of 1; (b) 'inverse skin effect' shows up at 1800 MHz, with respect to a 900 MHz source.

Enantiomeric separations of chiral pharmaceuticals using chirally modified tetrahexahedral Au nanoparticles

NASA Astrophysics Data System (ADS)

Shukla, N.; Yang, D.; Gellman, A. J.

2016-06-01

Tetrahexahedral (THH, 24-sided) Au nanoparticles modified with D- or L-cysteine (Cys) have been used as enantioselective separators of the chiral pharmaceutical propranolol (PLL) in solution phase. Polarimetry has been used to measure the rotation of linearly polarized light by solutions containing mixtures of PLL and Cys/THH-Au NPs with varying enantiomeric excesses of each. Polarimetry yields clear evidence of enantiospecific adsorption of PLL onto the Cys/THH-Au NPs. This extends prior work using propylene oxide as a test chiral probe, by using the crystalline THH Au NPs with well-defined facets to separate a real pharmaceutical. This work suggests that chiral nanoparticles, coupled with a density separation method such as centrifugation, could be used for enantiomeric purification of real pharmaceuticals. A simple robust model developed earlier has also been used to extract the enantiospecific equilibrium constants for R- and S-PLL adsorption onto the D- and L-Cys/THH-Au NPs.

Hierarchical chirality transfer in the growth of Towel Gourd tendrils

PubMed Central

Wang, Jian-Shan; Wang, Gang; Feng, Xi-Qiao; Kitamura, Takayuki; Kang, Yi-Lan; Yu, Shou-Wen; Qin, Qing-Hua

2013-01-01

Chirality plays a significant role in the physical properties and biological functions of many biological materials, e.g., climbing tendrils and twisted leaves, which exhibit chiral growth. However, the mechanisms underlying the chiral growth of biological materials remain unclear. In this paper, we investigate how the Towel Gourd tendrils achieve their chiral growth. Our experiments reveal that the tendrils have a hierarchy of chirality, which transfers from the lower levels to the higher. The change in the helical angle of cellulose fibrils at the subcellular level induces an intrinsic torsion of tendrils, leading to the formation of the helical morphology of tendril filaments. A chirality transfer model is presented to elucidate the chiral growth of tendrils. This present study may help understand various chiral phenomena observed in biological materials. It also suggests that chirality transfer can be utilized in the development of hierarchically chiral materials having unique properties. PMID:24173107

Searches for anomalous coupling in top-quark interaction with the W boson and b quark, along with searches for quark-flavor-changing neutral currents, in an analysis of data from the CMS experiment

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

Boos, E. E.; Bunichev, V. E.; Vorotnikov, G. A.

2016-01-15

The results of searches for effects beyond the Standard Model in processes of single top-quark production in the CMS experiment are presented. Anomalous contributions of the vector and magnetic types in top-quark interaction with the W boson and b quark and quark-flavor-changing neutral currents in top-quark interaction with the c or u quark via gluon exchange were studied. The respective analysis was performed with the aid of Bayesian neural networks. No statistically significant deviations were found, and upper limits on anomalous couplings at a 95% confidence level were set.

Active chiral fluids.

PubMed

Fürthauer, S; Strempel, M; Grill, S W; Jülicher, F

2012-09-01

Active processes in biological systems often exhibit chiral asymmetries. Examples are the chirality of cytoskeletal filaments which interact with motor proteins, the chirality of the beat of cilia and flagella as well as the helical trajectories of many biological microswimmers. Here, we derive constitutive material equations for active fluids which account for the effects of active chiral processes. We identify active contributions to the antisymmetric part of the stress as well as active angular momentum fluxes. We discuss four types of elementary chiral motors and their effects on a surrounding fluid. We show that large-scale chiral flows can result from the collective behavior of such motors even in cases where isolated motors do not create a hydrodynamic far field.

Chiroptical studies on supramolecular chirality of molecular aggregates.

PubMed

Sato, Hisako; Yajima, Tomoko; Yamagishi, Akihiko

2015-10-01

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

Meson and baryon spectrum for QCD with two light dynamical quarks

NASA Astrophysics Data System (ADS)

Engel, Georg P.; Lang, C. B.; Limmer, Markus; Mohler, Daniel; Schäfer, Andreas

2010-08-01

We present results of meson and baryon spectroscopy using the Chirally Improved Dirac operator on lattices of size 163×32 with two mass-degenerate light sea quarks. Three ensembles with pion masses of 322(5), 470(4), and 525(7) MeV and lattice spacings close to 0.15 fm are investigated. Results for ground and excited states for several channels are given, including spin two mesons and hadrons with strange valence quarks. The analysis of the states is done with the variational method, including two kinds of Gaussian sources and derivative sources. We obtain several ground states fairly precisely and find radial excitations in various channels. Excited baryon results seem to suffer from finite size effects, in particular, at small pion masses. We discuss the possible appearance of scattering states, considering masses and eigenvectors. Partially quenched results in the scalar channel suggest the presence of a 2-particle state, however, in most channels we cannot identify them. Where available, we compare our results to results of quenched simulations using the same action.

Waves in magnetized quark matter

NASA Astrophysics Data System (ADS)

Fogaça, D. A.; Sanches, S. M.; Navarra, F. S.

2018-05-01

We study wave propagation in a non-relativistic cold quark-gluon plasma immersed in a constant magnetic field. Starting from the Euler equation we derive linear wave equations and investigate their stability and causality. We use a generic form for the equation of state, the EOS derived from the MIT bag model and also a variant of the this model which includes gluon degrees of freedom. The results of this analysis may be relevant for perturbations propagating through the quark matter phase in the core of compact stars and also for perturbations propagating in the low temperature quark-gluon plasma formed in low energy heavy ion collisions, to be carried out at FAIR and NICA.

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

PubMed

Yamamoto, Arata

2011-07-15

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

Bottom-quark forward-backward asymmetry in the standard model and beyond.

PubMed

Grinstein, Benjamín; Murphy, Christopher W

2013-08-09

We computed the bottom-quark forward-backward asymmetry at the Tevatron in the standard model (SM) and for several new physics scenarios. Near the Z pole, the SM bottom asymmetry is dominated by tree level exchanges of electroweak gauge bosons. While above the Z pole, next-to-leading order QCD dominates the SM asymmetry as was the case with the top-quark forward-backward asymmetry. Light new physics, M(NP)≲150  GeV, can cause significant deviations from the SM prediction for the bottom asymmetry. The bottom asymmetry can be used to distinguish between competing new physics (NP) explanations of the top asymmetry based on how the NP interferes with s-channel gluon and Z exchange.

Formation of Enhanced Uniform Chiral Fields in Symmetric Dimer Nanostructures

PubMed Central

Tian, Xiaorui; Fang, Yurui; Sun, Mengtao

2015-01-01

Chiral fields with large optical chirality are very important in chiral molecules analysis, sensing and other measurements. Plasmonic nanostructures have been proposed to realize such super chiral fields for enhancing weak chiral signals. However, most of them cannot provide uniform chiral near-fields close to the structures, which makes these nanostructures not so efficient for applications. Plasmonic helical nanostructures and blocked squares have been proved to provide uniform chiral near-fields, but structure fabrication is a challenge. In this paper, we show that very simple plasmonic dimer structures can provide uniform chiral fields in the gaps with large enhancement of both near electric fields and chiral fields under linearly polarized light illumination with polarization off the dimer axis at dipole resonance. An analytical dipole model is utilized to explain this behavior theoretically. 30 times of volume averaged chiral field enhancement is gotten in the whole gap. Chiral fields with opposite handedness can be obtained simply by changing the polarization to the other side of the dimer axis. It is especially useful in Raman optical activity measurement and chiral sensing of small quantity of chiral molecule. PMID:26621558

Acylation of Chiral Alcohols: A Simple Procedure for Chiral GC Analysis.

PubMed

Oromí-Farrús, Mireia; Torres, Mercè; Canela, Ramon

2012-01-01

The use of iodine as a catalyst and either acetic or trifluoroacetic acid as a derivatizing reagent for determining the enantiomeric composition of acyclic and cyclic aliphatic chiral alcohols was investigated. Optimal conditions were selected according to the molar ratio of alcohol to acid, the reaction time, and the reaction temperature. Afterwards, chiral stability of chiral carbons was studied. Although no isomerization was observed when acetic acid was used, partial isomerization was detected with the trifluoroacetic acid. A series of chiral alcohols of a widely varying structural type were then derivatized with acetic acid using the optimal conditions. The resolution of the enantiomeric esters and the free chiral alcohols was measured using a capillary gas chromatograph equipped with a CP Chirasil-DEX CB column. The best resolutions were obtained with 2-pentyl acetates (α = 3.00) and 2-hexyl acetates (α = 1.95). This method provides a very simple and efficient experimental workup procedure for analyzing chiral alcohols by chiral-phase GC.

Measurements of the u valence quark distribution function in the proton and u quark fragmentation functions

NASA Astrophysics Data System (ADS)

Arneodo, M.; Arvidson, A.; Aubert, J. J.; Badelek, B.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I. G.; Blum, D.; Böhm, E.; De Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S. C.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Clifft, R.; Coignet, G.; Combley, F.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Düren, M.; Eckardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Jaffre, M.; Jacholkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, A.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Peschel, H.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Poensgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Sandacz, A.; Scheer, M.; Schlagböhmer, A.; Schiemann, H.; Schmitz, N.; Schneegans, M.; Scholz, M.; Schouten, M.; Schröder, T.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thenard, J. M.; Thompson, J. C.; De la Torre, A.; Toth, J.; Urban, L.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.; Wolf, G.; European Muon Collaboration

1989-07-01

A new determination of the u valence quark distribution function in the proton is obtained from the analysis of identified charged pions, kaons, protons and antiprotons produced in muon-proton and muon-deuteron scattering. The comparison with results obtained in inclusive deep inelastic lepton-nucleon scattering provides a further test of the quark-parton model. The u quark fragmentation functions into positive and negative pions, kaons, protons and antiprotons are also measured.

Effects of the nucleon radius on neutron stars in a quark mean field model

NASA Astrophysics Data System (ADS)

Zhu, Zhen-Yu; Li, Ang

2018-03-01

We study the effects of free space nucleon radius on nuclear matter and neutron stars within the framework of the quark mean field model. The nucleon radius is treated self-consistently with this model, where quark confinement is adjusted to fit different values of nucleon radius. Corrections due to center-of-mass motion, quark-pion coupling, and one gluon exchange are included to obtain the nucleon mass in vacuum. The meson coupling constants that describe the behavior of the many-body nucleonic system are constructed by reproducing the empirical saturation properties of nuclear matter, including the recent determinations of symmetry energy parameters. Our results show that the nucleon radius in free space has negligible effects on the nuclear matter equation of state and neutron star mass-radius relations, which is different from the conclusion drawn in previous studies. We further explore that the sensitivity of star radius on the nucleon radius found in earlier publications is actually from the symmetry energy and its slope.

Chiral Polymers.

DTIC Science & Technology

1984-10-01

regardless of the method of polymerization. The styrene-bead copolymers were packed in HPLC columns, but none were especiall, effective in separating...enantiomers in a racemic mixture. The chiral butyrolactone polymer was coated on silica, but this material did not effect resolution of racemic mixtures in an...been effected utilizing chiral oxazolines3 prompted the initial efforts to synthesize various chiral 2-vinyl- oxazoline monomers for incorporation

Molecular-Level Design of Heterogeneous Chiral Catalysis

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

Francisco Zaera

2012-03-21

The following is a proposal to continue our multi-institutional research on heterogeneous chiral catalysis. Our team combines the use of surface-sensitive analytical techniques for the characterization of model systems with quantum and statistical mechanical calculations to interpret experimental data and guide the design of future research. Our investigation focuses on the interrelation among the three main mechanisms by which enantioselectivity can be bestowed to heterogeneous catalysts, namely: (1) by templating chirality via the adsorption of chiral supramolecular assemblies, (2) by using chiral modifiers capable of forming chiral complexes with the reactant and force enantioselective surface reactions, and (3) by formingmore » naturally chiral surfaces using imprinting chiral agents. Individually, the members of our team are leaders in these various aspects of chiral catalysis, but the present program provides the vehicle to generate and exploit the synergies necessary to address the problem in a comprehensive manner. Our initial work has advanced the methodology needed for these studies, including an enantioselective titration procedure to identify surface chiral sites, infrared spectroscopy in situ at the interface between gases or liquids and solids to mimic realistic catalytic conditions, and DFT and Monte Carlo algorithms to simulate and understand chirality on surfaces. The next step, to be funded by the monies requested in this proposal, is to apply those methods to specific problems in chiral catalysis, including the identification of the requirements for the formation of supramolecular surface structures with enantioselective behavior, the search for better molecules to probe the chiral nature of the modified surfaces, the exploration of the transition from supramolecular to one-to-one chiral modification, the correlation of the adsorption characteristics of one-to-one chiral modifiers with their physical properties, in particular with their

Light-quarks Yukawa couplings and new physics in exclusive high-pT Higgs boson +jet and Higgs boson + b -jet events

NASA Astrophysics Data System (ADS)

Cohen, Jonathan; Bar-Shalom, Shaouly; Eilam, Gad; Soni, Amarjit

2018-03-01

We suggest that the exclusive Higgs +light (or b)-jet production at the LHC, p p →h +j (jb), is a rather sensitive probe of the light-quarks Yukawa couplings and of other forms of new physics (NP) in the Higgs-gluon h g g and quark-gluon q q g interactions. We study the Higgs pT-distribution in p p →h +j (jb)→γ γ +j (jb), i.e., in h +j (jb) production followed by the Higgs decay h →γ γ , employing the (pT-dependent) signal strength formalism to probe various types of NP which are relevant to these processes and which we parametrize either as scaled Standard Model (SM) couplings (the kappa-framework) and/or through new higher dimensional effective operators (the SMEFT framework). We find that the exclusive h +j (jb) production at the 13 TeV LHC is sensitive to various NP scenarios, with typical scales ranging from a few TeV to O (10 ) TeV , depending on the flavor, chirality and Lorentz structure of the underlying physics.

Can a Non-Chiral Object Be Made of Two Identical Chiral Moieties?

ERIC Educational Resources Information Center

LeMarechal, Jean Francois

2008-01-01

Several pedagogical objects can be used to discuss chirality. Here, we use the cut of an apple to show that the association of identical chiral moieties can form a non-chiral object. Octahedral chirality is used to find situations equivalent to the cut of the apple. (Contains 5 figures.)

Phonon Dispersion in Chiral Single-Wall Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Mu, Weihua; Vamivakas, Anthony Nickolas; Fang, Yan; Wang, Bolin

The method to obtain phonon dispersion of achiral single-wall carbon nanotubes (SWNTs) from 6×6 matrix proposed by Mahan and Jeon7 has been extended to chiral SWNTs. The number of calculated phonon modes of a chiral SWNT (10, 1) is much larger than that of a zigzag one (10, 0) because the number of atoms in the translational unit cell of chiral SWNT is larger than that of an achiral one even though they have relative similar radius. The possible application of our approach to other models with more phonon potential terms beyond Mahan and Jeon's model is discussed.

Critical end point in the presence of a chiral chemical potential

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

Cui, Z. -F.; Cloët, I. C.; Lu, Y.

A class of Polyakov-loop-modified Nambu-Jona-Lasinio models has been used to support a conjecture that numerical simulations of lattice-regularized QCD defined with a chiral chemical potential can provide information about the existence and location of a critical end point in the QCD phase diagram drawn in the plane spanned by baryon chemical potential and temperature. That conjecture is challenged by conflicts between the model results and analyses of the same problem using simulations of lattice-regularized QCD (lQCD) and well-constrained Dyson-Schwinger equation (DSE) studies. We find the conflict is resolved in favor of the lQCD and DSE predictions when both a physicallymore » motivated regularization is employed to suppress the contribution of high-momentum quark modes in the definition of the effective potential connected with the Polyakov-loop-modified Nambu-Jona-Lasinio models and the four-fermion coupling in those models does not react strongly to changes in the mean field that is assumed to mock-up Polyakov-loop dynamics. With the lQCD and DSE predictions thus confirmed, it seems unlikely that simulations of lQCD with mu(5) > 0 can shed any light on a critical end point in the regular QCD phase diagram.« less

Enhanced Chiral Discriminatory van der Waals Interactions Mediated by Chiral Surfaces

NASA Astrophysics Data System (ADS)

Barcellona, Pablo; Safari, Hassan; Salam, A.; Buhmann, Stefan Yoshi

2017-05-01

We predict a discriminatory interaction between a chiral molecule and an achiral molecule which is mediated by a chiral body. To achieve this, we generalize the van der Waals interaction potential between two ground-state molecules with electric, magnetic, and chiral response to nontrivial environments. The force is evaluated using second-order perturbation theory with an effective Hamiltonian. Chiral media enhance or reduce the free interaction via many-body interactions, making it possible to measure the chiral contributions to the van der Waals force with current technology. The van der Waals interaction is discriminatory with respect to enantiomers of different handedness and could be used to separate enantiomers. We also suggest a specific geometric configuration where the electric contribution to the van der Waals interaction is zero, making the chiral component the dominant effect.

Single top quarks and dark matter

NASA Astrophysics Data System (ADS)

Pinna, Deborah; Zucchetta, Alberto; Buckley, Matthew R.; Canelli, Florencia

2017-08-01

Processes with dark matter interacting with the standard model fermions through new scalars or pseudoscalars with flavor-diagonal couplings proportional to fermion mass are well motivated theoretically, and provide a useful phenomenological model with which to interpret experimental results. Two modes of dark matter production from these models have been considered in the existing literature: pairs of dark matter produced through top quark loops with an associated monojet in the event, and pair production of dark matter with pairs of heavy flavored quarks (tops or bottoms). In this paper, we demonstrate that a third, previously overlooked channel yields a non-negligible contribution to LHC dark matter searches in these models. In spite of a generally lower production cross section at LHC when compared to the associated top-pair channel, non-flavor violating single top quark processes are kinematically favored and can significantly increase the sensitivity to these models. Including dark matter production in association with a single top quark through scalar or pseudoscalar mediators, the exclusion limit set by the LHC searches for dark matter can be improved by 30% up to a factor of two, depending on the mass assumed for the mediator particle.

The Kaon B-parameter in mixed action chiral perturbation theory

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

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

2006-09-01

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

Experimental constraint on quark electric dipole moments

NASA Astrophysics Data System (ADS)

Liu, Tianbo; Zhao, Zhiwen; Gao, Haiyan

2018-04-01

The electric dipole moments (EDMs) of nucleons are sensitive probes of additional C P violation sources beyond the standard model to account for the baryon number asymmetry of the universe. As a fundamental quantity of the nucleon structure, tensor charge is also a bridge that relates nucleon EDMs to quark EDMs. With a combination of nucleon EDM measurements and tensor charge extractions, we investigate the experimental constraint on quark EDMs, and its sensitivity to C P violation sources from new physics beyond the electroweak scale. We obtain the current limits on quark EDMs as 1.27 ×10-24 e .cm for the up quark and 1.17 ×10-24 e .cm for the down quark at the scale of 4 GeV2 . We also study the impact of future nucleon EDM and tensor charge measurements, and show that upcoming new experiments will improve the constraint on quark EDMs by about 3 orders of magnitude leading to a much more sensitive probe of new physics models.

The discovery of quarks

NASA Astrophysics Data System (ADS)

Friedman, J. I.

2001-01-01

In the period following World War II, there was a rapid development of particle physics. With the construction of synchrotrons and the development of detector technology, many new particles were discovered and the systematics of their interactions investigated. The invention of the bubble chamber played an especially important role in uncovering the rich array of hadrons that were discovered in this period.In 1961 Murray Gell-Mann [1] and Yuval Ne'eman [2] independently introduced a classification scheme, based on SU(3) symmetry, which placed hadrons into families on the basis of spin and parity. Like the periodic table for the elements, this scheme was predictive as well as descriptive, and various hadrons, such as the - , were predicted within this framework and were later discovered.In 1964 Gell-Mann [3] and George Zweig [4] independently proposed quarks as the building blocks of hadrons as a way of generating the SU(3) classification scheme. When the quark model was first proposed, it postulated three types of quarks: up (u), down (d), and strange (s), with charges 2/3, - 1/3, and - 1/3 respectively. Each of these was hypothesized to be a spin1/2 particle. In this model the nucleon (and all other baryons) is made up of three quarks, and each meson consists of a quark and an antiquark. For example, as the proton and neutron both have ero strangeness, they are (u,u,d) and (d,d,u) systems respectively.

Chiral plasmonics

PubMed Central

Hentschel, Mario; Schäferling, Martin; Duan, Xiaoyang; Giessen, Harald; Liu, Na

2017-01-01

We present a comprehensive overview of chirality and its optical manifestation in plasmonic nanosystems and nanostructures. We discuss top-down fabricated structures that range from solid metallic nanostructures to groupings of metallic nanoparticles arranged in three dimensions. We also present the large variety of bottom-up synthesized structures. Using DNA, peptides, or other scaffolds, complex nanoparticle arrangements of up to hundreds of individual nanoparticles have been realized. Beyond this static picture, we also give an overview of recent demonstrations of active chiral plasmonic systems, where the chiral optical response can be controlled by an external stimulus. We discuss the prospect of using the unique properties of complex chiral plasmonic systems for enantiomeric sensing schemes. PMID:28560336

Discovery of the fourth quark in the Standard Model

Science.gov Websites

, using the MARK I detector, (above left) and on the East Coast, at DOE’s Brookhaven Laboratory Burton Richter at DOE’s SLAC Sam Ting and team at DOE's Brookhaven 1974 The discovery of charm , the fourth quark in the Standard Model, occurred simultaneously on the West Coast, at DOE’s SLAC

Balance of baryon number in the quark coalescence model

NASA Astrophysics Data System (ADS)

Bialas, A.; Rafelski, J.

2006-02-01

The charge and baryon balance functions are studied in the coalescence hadronization mechanism of quark-gluon plasma. Assuming that in the plasma phase the qqbar pairs form uncorrelated clusters whose decay is also uncorrelated, one can understand the observed small width of the charge balance function in the Gaussian approximation. The coalescence model predicts even smaller width of the baryon-antibaryon balance function: σBBbar /σ+ - =√{ 2 / 3 }.

Thermal chiral vortical and magnetic waves: New excitation modes in chiral fluids

DOE PAGES

Kalaydzhyan, Tigran; Murchikova, Elena

2017-03-24

In certain circumstances, chiral (parity-violating) medium can be described hydrodynamically as a chiral fluid with microscopic quantum anomalies. Possible examples of such systems include strongly coupled quark–gluon plasma, liquid helium 3He-A, neutron stars and the Early Universe. Here, we study first-order hy-drodynamics of a chiral fluid on a vortex background and in an external magnetic field. We show that there are two previously undiscovered modes describing heat waves propagating along the vortex and magnetic field. We call them the Thermal Chiral Vortical Wave and Thermal Chiral Magnetic Wave. We also identify known gapless excitations of density (chiral vortical and chiralmore » magnetic waves) and transverse velocity (chiral Alfvén wave). We also demonstrate that the velocity of the chiral vortical wave is zero, when the full hydrodynamic framework is applied, and hence the wave is absent and the excitation reduces to the charge diffusion mode. We also comment on the frame-dependent contributions to the obtained propagation velocities.« less

Chiral supramolecular organization from a sheet-like achiral gel: a study of chiral photoinduction.

PubMed

Royes, Jorge; Polo, Víctor; Uriel, Santiago; Oriol, Luis; Piñol, Milagros; Tejedor, Rosa M

2017-05-31

Chiral photoinduction in a photoresponsive gel based on an achiral 2D architecture with high geometric anisotropy and low roughness has been investigated. Circularly polarized light (CPL) was used as a chiral source and an azobenzene chromophore was employed as a chiral trigger. The chiral photoinduction was studied by evaluating the preferential excitation of enantiomeric conformers of the azobenzene units. Crystallographic data and density functional theory (DFT) calculations show how chirality is transferred to the achiral azomaterials as a result of the combination of chiral photochemistry and supramolecular interactions. This procedure could be applied to predict and estimate chirality transfer from a chiral physical source to a supramolecular organization using different light-responsive units.

Quark-Meson-Coupling (QMC) model for finite nuclei, nuclear matter and beyond

NASA Astrophysics Data System (ADS)

Guichon, P. A. M.; Stone, J. R.; Thomas, A. W.

2018-05-01

The Quark-Meson-Coupling model, which self-consistently relates the dynamics of the internal quark structure of a hadron to the relativistic mean fields arising in nuclear matter, provides a natural explanation to many open questions in low energy nuclear physics, including the origin of many-body nuclear forces and their saturation, the spin-orbit interaction and properties of hadronic matter at a wide range of densities up to those occurring in the cores of neutron stars. Here we focus on four aspects of the model (i) a full comprehensive survey of the theory, including the latest developments, (ii) extensive application of the model to ground state properties of finite nuclei and hypernuclei, with a discussion of similarities and differences between the QMC and Skyrme energy density functionals, (iii) equilibrium conditions and composition of hadronic matter in cold and warm neutron stars and their comparison with the outcome of relativistic mean-field theories and, (iv) tests of the fundamental idea that hadron structure changes in-medium.

Template-based and free modeling of I-TASSER and QUARK pipelines using predicted contact maps in CASP12.

PubMed

Zhang, Chengxin; Mortuza, S M; He, Baoji; Wang, Yanting; Zhang, Yang

2018-03-01

We develop two complementary pipelines, "Zhang-Server" and "QUARK", based on I-TASSER and QUARK pipelines for template-based modeling (TBM) and free modeling (FM), and test them in the CASP12 experiment. The combination of I-TASSER and QUARK successfully folds three medium-size FM targets that have more than 150 residues, even though the interplay between the two pipelines still awaits further optimization. Newly developed sequence-based contact prediction by NeBcon plays a critical role to enhance the quality of models, particularly for FM targets, by the new pipelines. The inclusion of NeBcon predicted contacts as restraints in the QUARK simulations results in an average TM-score of 0.41 for the best in top five predicted models, which is 37% higher than that by the QUARK simulations without contacts. In particular, there are seven targets that are converted from non-foldable to foldable (TM-score >0.5) due to the use of contact restraints in the simulations. Another additional feature in the current pipelines is the local structure quality prediction by ResQ, which provides a robust residue-level modeling error estimation. Despite the success, significant challenges still remain in ab initio modeling of multi-domain proteins and folding of β-proteins with complicated topologies bound by long-range strand-strand interactions. Improvements on domain boundary and long-range contact prediction, as well as optimal use of the predicted contacts and multiple threading alignments, are critical to address these issues seen in the CASP12 experiment. © 2017 Wiley Periodicals, Inc.

Top Quark Properties at the TeVatron

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

Peters, Yvonne

2011-03-01

Discovered in 1995 by CDF and D0 at the Fermilab Tevatron collider, the top quark remains interesting to test the Standard Model. Having collected more than 7 fb{sup -1} of integrated luminosity with both experiments until today, several top quark properties have been measured with increasing precision, while other properties have been investigated for the first time. In this article recent measurements of top quark properties from CDF and D0 are presented, using between 1 fb{sup -1} and 4.8 fb{sup -1} of data. In particular, the measurement of the top quark mass, the top quark width, the top antitop massmore » difference, a check of the electric charge of the top quark, measurements of the top antitop quark spin correlation and W helicity as well as a search for charged Higgs bosons are discussed.« less

Lock-in of a Chiral Soliton Lattice by Itinerant Electrons

NASA Astrophysics Data System (ADS)

Okumura, Shun; Kato, Yasuyuki; Motome, Yukitoshi

2018-03-01

Chiral magnets often show intriguing magnetic and transport properties associated with their peculiar spin textures. A typical example is a chiral soliton lattice, which is found in monoaxial chiral magnets, such as CrNb3S6 and Yb(Ni1-xCux)3Al9 in an external magnetic field perpendicular to the chiral axis. Here, we theoretically investigate the electronic and magnetic properties in the chiral soliton lattice by a minimal itinerant electron model. Using variational calculations, we find that the period of the chiral soliton lattice can be locked at particular values dictated by the Fermi wave number, in stark contrast to spin-only models. We discuss this behavior caused by the spin-charge coupling as a possible mechanism for the lock-in discovered in Yb(Ni1-xCux)3Al9 [T. Matsumura et al., J. Phys. Soc. Jpn. 86, 124702 (2017)]. We also show that the same mechanism leads to the spontaneous formation of the chiral soliton lattice even in the absence of the magnetic field.

Patterns and partners for chiral symmetry restoration

NASA Astrophysics Data System (ADS)

Gómez Nicola, A.; Ruiz de Elvira, J.

2018-04-01

We present and analyze a new set of Ward Identities which shed light on the distinction between different patterns of chiral symmetry restoration in QCD, namely O (4 ) vs O (4 )×U (1 )A. The degeneracy of chiral partners for all scalar and pseudoscalar meson nonet members is studied through their corresponding correlators. Around chiral symmetry degeneration of O (4 ) partners, our analysis predicts that U (1 )A partners are also degenerated. Our analysis also leads to I =1 /2 scalar-pseudoscalar partner degeneration at exact chiral restoration and supports ideal mixing between the η - η' and the f0(500 )- f0(980 ) mesons at O (4 )×U (1 )A restoration, with a possible range where the pseudoscalar mixing vanishes if the two transitions are well separated. We test our results with lattice data and provide further relevant observables regarding chiral and U (1 )A restoration for future lattice and model analyses.

Characterizing optical chirality

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

Bliokh, Konstantin Y.; Advanced Science Institute, RIKEN, Wako-shi, Saitama 351-0198; Nori, Franco

We examine the recently introduced measure of chirality of a monochromatic optical field [Y. Tang and A. E. Cohen, Phys. Rev. Lett. 104, 163901 (2010)] using the momentum (plane-wave) representation and helicity basis. Our analysis clarifies the physical meaning of the measure of chirality and unveils its close relation to the polarization helicity, spin angular momentum, energy density, and Poynting energy flow. We derive the operators of the optical chirality and of the corresponding chiral momentum, which acquire remarkably simple forms in the helicity representation.

Chiral Symmetry Breaking in Peptide Systems During Formation of Life on Earth.

PubMed

Konstantinov, Konstantin K; Konstantinova, Alisa F

2018-03-01

Chiral symmetry breaking in complex chemical systems with a large number of amino acids and a large number of similar reactions was considered. It was shown that effective averaging over similar reaction channels may result in very weak effective enantioselectivity of forward reactions, which does not allow most of the known models to result in chiral symmetry breaking during formation of life on Earth. Models with simple and catalytic synthesis of a single amino acid, formation of peptides up to length five, and sedimentation of insoluble pair of substances were considered. It was shown that depending on the model and the values of the parameters, chiral symmetry breaking may occur in up to about 10% out of all possible unique insoluble pair combinations even in the absence of any catalytic synthesis and that minimum total number of amino acids in the pair is 5. If weak enantioselective forward catalytic synthesis of amino acids is present, then the number of possible variants, in which chiral symmetry breaking may occur, increases substantially. It was shown that that the most interesting catalysts have zero or one amino acid of "incorrect" chirality. If the parameters of the model are adjusted in such a way to result in an increase of concentration of longer peptides, then catalysts with two amino acids of incorrect chirality start to appear at peptides of length five. Models of chiral symmetry breaking in the presence of epimerization were considered for peptides up to length three. It was shown that the range of parameters in which chiral symmetry breaking could occur significantly shrinks in comparison to previously considered models with peptides up to length two. An experiment of chiral symmetry breaking was proposed. The experiment consists of a three-step cycle: reversible catalytic synthesis of amino acids, reversible synthesis of peptides, and irreversible sedimentation of insoluble substances.

Chiral Symmetry Breaking in Peptide Systems During Formation of Life on Earth

NASA Astrophysics Data System (ADS)

Konstantinov, Konstantin K.; Konstantinova, Alisa F.

2018-03-01

Chiral symmetry breaking in complex chemical systems with a large number of amino acids and a large number of similar reactions was considered. It was shown that effective averaging over similar reaction channels may result in very weak effective enantioselectivity of forward reactions, which does not allow most of the known models to result in chiral symmetry breaking during formation of life on Earth. Models with simple and catalytic synthesis of a single amino acid, formation of peptides up to length five, and sedimentation of insoluble pair of substances were considered. It was shown that depending on the model and the values of the parameters, chiral symmetry breaking may occur in up to about 10% out of all possible unique insoluble pair combinations even in the absence of any catalytic synthesis and that minimum total number of amino acids in the pair is 5. If weak enantioselective forward catalytic synthesis of amino acids is present, then the number of possible variants, in which chiral symmetry breaking may occur, increases substantially. It was shown that that the most interesting catalysts have zero or one amino acid of "incorrect" chirality. If the parameters of the model are adjusted in such a way to result in an increase of concentration of longer peptides, then catalysts with two amino acids of incorrect chirality start to appear at peptides of length five. Models of chiral symmetry breaking in the presence of epimerization were considered for peptides up to length three. It was shown that the range of parameters in which chiral symmetry breaking could occur significantly shrinks in comparison to previously considered models with peptides up to length two. An experiment of chiral symmetry breaking was proposed. The experiment consists of a three-step cycle: reversible catalytic synthesis of amino acids, reversible synthesis of peptides, and irreversible sedimentation of insoluble substances.

Tevatron Top-Quark Combinations and World Top-Quark Mass Combination

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

Peters, Reinhild Yvonne

2014-11-04

Almost 20 years after its discovery, the top quark is still an interesting particle, undergoing precise investigation of its properties. For many years, the Tevatron proton antiproton collider at Fermilab was the only place to study top quarks in detail, while with the recent start of the LHC proton proton collider a top quark factory has opened. An important ingredient for the full understanding of the top quark is the combination of measurements from the individual experiments. In particular, the Tevaton combinations of single top-quark cross sections, the ttbar production cross section, the W helicity in top-quark decays as wellmore » as the Tevatron and the world combination of the top-quark mass are discussed.« less

Basic features of the pion valence-quark distribution function

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

Chang, Lei; Mezrag, Cédric; Moutarde, Hervé

2014-10-07

The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbow–ladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables amore » realistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, q π(x); namely, at a characteristic hadronic scale, q π(x)~(1-x) 2 for x≳0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.« less

Chirality and gravitational parity violation.

PubMed

Bargueño, Pedro

2015-06-01

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

Chirality measures of α-amino acids.

PubMed

Jamróz, Michał H; Rode, Joanna E; Ostrowski, Sławomir; Lipiński, Piotr F J; Dobrowolski, Jan Cz

2012-06-25

To measure molecular chirality, the molecule is treated as a finite set of points in the Euclidean R(3) space supplemented by k properties, p(1)((i)), p(2)((i)), ..., p(k)((i)) assigned to the ith atom, which constitute a point in the Property P(k) space. Chirality measures are described as the distance between a molecule and its mirror image minimized over all its arbitrary orientation-preserving isometries in the R(3) × P(k) Cartesian product space. Following this formalism, different chirality measures can be estimated by taking into consideration different sets of atomic properties. Here, for α-amino acid zwitterionic structures taken from the Cambridge Structural Database and for all 1684 neutral conformers of 19 biogenic α-amino acid molecules, except glycine and cystine, found at the B3LYP/6-31G** level, chirality measures have been calculated by a CHIMEA program written in this project. It is demonstrated that there is a significant correlation between the measures determined for the α-amino acid zwitterions in crystals and the neutral forms in the gas phase. Performance of the studied chirality measures with changes of the basis set and computation method was also checked. An exemplary quantitative structure–activity relationship (QSAR) application of the chirality measures was presented by an introductory model for the benchmark Cramer data set of steroidal ligands of the sex-hormone binding globulin.

Cell chirality: emergence of asymmetry from cell culture.

PubMed

Wan, Leo Q; Chin, Amanda S; Worley, Kathryn E; Ray, Poulomi

2016-12-19

Increasing evidence suggests that intrinsic cell chirality significantly contributes to the left-right (LR) asymmetry in embryonic development, which is a well-conserved characteristic of living organisms. With animal embryos, several theories have been established, but there are still controversies regarding mechanisms associated with embryonic LR symmetry breaking and the formation of asymmetric internal organs. Recently, in vitro systems have been developed to determine cell chirality and to recapitulate multicellular chiral morphogenesis on a chip. These studies demonstrate that chirality is indeed a universal property of the cell that can be observed with well-controlled experiments such as micropatterning. In this paper, we discuss the possible benefits of these in vitro systems to research in LR asymmetry, categorize available platforms for single-cell chirality and multicellular chiral morphogenesis, and review mathematical models used for in vitro cell chirality and its applications in in vivo embryonic development. These recent developments enable the interrogation of the intracellular machinery in LR axis establishment and accelerate research in birth defects in laterality.This article is part of the themed issue 'Provocative questions in left-right asymmetry'. © 2016 The Author(s).

Cell chirality: emergence of asymmetry from cell culture

PubMed Central

Wan, Leo Q.; Chin, Amanda S.; Worley, Kathryn E.; Ray, Poulomi

2016-01-01

Increasing evidence suggests that intrinsic cell chirality significantly contributes to the left–right (LR) asymmetry in embryonic development, which is a well-conserved characteristic of living organisms. With animal embryos, several theories have been established, but there are still controversies regarding mechanisms associated with embryonic LR symmetry breaking and the formation of asymmetric internal organs. Recently, in vitro systems have been developed to determine cell chirality and to recapitulate multicellular chiral morphogenesis on a chip. These studies demonstrate that chirality is indeed a universal property of the cell that can be observed with well-controlled experiments such as micropatterning. In this paper, we discuss the possible benefits of these in vitro systems to research in LR asymmetry, categorize available platforms for single-cell chirality and multicellular chiral morphogenesis, and review mathematical models used for in vitro cell chirality and its applications in in vivo embryonic development. These recent developments enable the interrogation of the intracellular machinery in LR axis establishment and accelerate research in birth defects in laterality. This article is part of the themed issue ‘Provocative questions in left–right asymmetry’. PMID:27821525

A new model for soft gamma-ray repeaters and anomalous x-ray pulsars using quark stars

NASA Astrophysics Data System (ADS)

Niebergal, Brian Phillip

2007-05-01

If indeed the strange quark matter (SQM) hypothesis is true, then it is highly probable that some stars exist with an interior composed entirely of deconfined quarks. In this thesis the consequences of this SQM hypothesis are explored in the context of strange quark stars (QSs), and the manner in which they manifest themselves, namely Soft-Gamma ray Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs). Discussed in this thesis is the effect of the highly superconducting SQM, which is the formation of an Abrikosov lattice occupying the entire QS, and the result of spin-down on this lattice due to magnetic braking. By including a degenerate shell or torus surrounding the QS in this model, created during the quark-nova, SGRs and AXPs can be linked into a single classification and every observation of SGRs/AXPs to date can be explained.

Effect of molecular structure of tartrates on chiral recognition of tartrate-boric acid complex chiral selectors in chiral microemulsion electrokinetic chromatography.

PubMed

Hu, Shao-Qiang; Chen, Yong-Lei; Zhu, Hua-Dong; Shi, Hai-Jun; Yan, Na; Chen, Xing-Guo

2010-08-20

Eight l-tartrates and a d-tartrate with different alcohol moieties were used as chiral oils to prepare chiral microemulsions, which were utilized in conjunction with borate buffer to separate the enantiomers of beta-blockers or structurally related compounds by the chiral microemulsion electrokinetic chromatography (MEEKC) method. Among them, six were found to have a relatively good chiral separation performance and their chiral recognition effect in terms of both enantioselectivity and resolution increases linearly with the number of carbon atoms in the alkyl group of alcohol moiety. The tartrates containing alkyl groups of different structures but the same number of carbon atoms, i.e. one of straight chain and one of branched chain, provide similar enantioseparations. The trend was elucidated according to the changes in the difference of the steric matching between the molecules of two enantiomers and chiral selector. Furthermore, it was demonstrated for the first time that a water insoluble solid compound, di-i-butyl l-tartrate (mp. 73.5 degrees C), can be used as an oil to prepare a stable microemulsion to be used in the chiral MEEKC successfully. And a critical effect of the microemulsion for chiral separation, which has never been reported before, was found in this experiment, namely providing a hydrophobic environment to strengthen the interactions between the chiral selector and enantiomers. Copyright 2010 Elsevier B.V. All rights reserved.

Probing Quark-Gluon-Plasma properties with a Bayesian model-to-data comparison

NASA Astrophysics Data System (ADS)

Cai, Tianji; Bernhard, Jonah; Ke, Weiyao; Bass, Steffen; Duke QCD Group Team

2016-09-01

Experiments at RHIC and LHC study a special state of matter called the Quark Gluon Plasma (QGP), where quarks and gluons roam freely, by colliding relativistic heavy-ions. Given the transitory nature of the QGP, its properties can only be explored by comparing computational models of its formation and evolution to experimental data. The models fall, roughly speaking, under two categories-those solely using relativistic viscous hydrodynamics (pure hydro model) and those that in addition couple to a microscopic Boltzmann transport for the later evolution of the hadronic decay products (hybrid model). Each of these models has multiple parameters that encode the physical properties we want to probe and that need to be calibrated to experimental data, a task which is computationally expensive, but necessary for the knowledge extraction and determination of the models' quality. Our group has developed an analysis technique based on Bayesian Statistics to perform the model calibration and to extract probability distributions for each model parameter. Following the previous work that applies the technique to the hybrid model, we now perform a similar analysis on a pure-hydro model and display the posterior distributions for the same set of model parameters. We also develop a set of criteria to assess the quality of the two models with respect to their ability to describe current experimental data. Funded by Duke University Goldman Sachs Research Fellowship.

Monte Carlo simulations of nematic and chiral nematic shells

NASA Astrophysics Data System (ADS)

Wand, Charlie R.; Bates, Martin A.

2015-01-01

We present a systematic Monte Carlo simulation study of thin nematic and cholesteric shells with planar anchoring using an off-lattice model. The results obtained using the simple model correspond with previously published results for lattice-based systems, with the number, type, and position of defects observed dependent on the shell thickness with four half-strength defects in a tetrahedral arrangement found in very thin shells and a pair of defects in a bipolar (boojum) configuration observed in thicker shells. A third intermediate defect configuration is occasionally observed for intermediate thickness shells, which is stabilized in noncentrosymmetric shells of nonuniform thickness. Chiral nematic (cholesteric) shells are investigated by including a chiral term in the potential. Decreasing the pitch of the chiral nematic leads to a twisted bipolar (chiral boojum) configuration with the director twist increasing from the inner to the outer surface.

Silver Films with Hierarchical Chirality.

PubMed

Ma, Liguo; Cao, Yuanyuan; Duan, Yingying; Han, Lu; Che, Shunai

2017-07-17

Physical fabrication of chiral metallic films usually results in singular or large-sized chirality, restricting the optical asymmetric responses to long electromagnetic wavelengths. The chiral molecule-induced formation of silver films prepared chemically on a copper substrate through a redox reaction is presented. Three levels of chirality were identified: primary twisted nanoflakes with atomic crystal lattices, secondary helical stacking of these nanoflakes to form nanoplates, and tertiary micrometer-sized circinates consisting of chiral arranged nanoplates. The chiral Ag films exhibited multiple plasmonic absorption- and scattering-based optical activities at UV/Vis wavelengths based on their hierarchical chirality. The Ag films showed chiral selectivity for amino acids in catalytic electrochemical reactions, which originated from their primary atomic crystal lattices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quark Matter May Not Be Strange.

PubMed

Holdom, Bob; Ren, Jing; Zhang, Chen

2018-06-01

If quark matter is energetically favored over nuclear matter at zero temperature and pressure, then it has long been expected to take the form of strange quark matter (SQM), with comparable amounts of u, d, and s quarks. The possibility of quark matter with only u and d quarks (udQM) is usually dismissed because of the observed stability of ordinary nuclei. However, we find that udQM generally has lower bulk energy per baryon than normal nuclei and SQM. This emerges in a phenomenological model that describes the spectra of the lightest pseudoscalar and scalar meson nonets. Taking into account the finite size effects, udQM can be the ground state of baryonic matter only for baryon number A>A_{min} with A_{min}≳300. This ensures the stability of ordinary nuclei and points to a new form of stable matter just beyond the periodic table.

Quark Matter May Not Be Strange

NASA Astrophysics Data System (ADS)

Holdom, Bob; Ren, Jing; Zhang, Chen

2018-06-01

If quark matter is energetically favored over nuclear matter at zero temperature and pressure, then it has long been expected to take the form of strange quark matter (SQM), with comparable amounts of u , d , and s quarks. The possibility of quark matter with only u and d quarks (u d QM ) is usually dismissed because of the observed stability of ordinary nuclei. However, we find that u d QM generally has lower bulk energy per baryon than normal nuclei and SQM. This emerges in a phenomenological model that describes the spectra of the lightest pseudoscalar and scalar meson nonets. Taking into account the finite size effects, u d QM can be the ground state of baryonic matter only for baryon number A >Amin with Amin≳300 . This ensures the stability of ordinary nuclei and points to a new form of stable matter just beyond the periodic table.

Ratios of Vector and Pseudoscalar B Meson Decay Constants in the Light-Cone Quark Model

NASA Astrophysics Data System (ADS)

Dhiman, Nisha; Dahiya, Harleen

2018-05-01

We study the decay constants of pseudoscalar and vector B meson in the framework of light-cone quark model. We apply the variational method to the relativistic Hamiltonian with the Gaussian-type trial wave function to obtain the values of β (scale parameter). Then with the help of known values of constituent quark masses, we obtain the numerical results for the decay constants f_P and f_V, respectively. We compare our numerical results with the existing experimental data.

Neutron Electric Dipole Moment in the Standard Model: Complete Three-Loop Calculation of the Valence Quark Contributions

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

Czarnecki, A.; Krause, B.

1997-06-01

We present a complete three-loop calculation of the electric dipole moment of the u and d quarks in the standard model. For the d quark, more relevant for the experimentally important neutron electric dipole moment, we find cancellations which lead to an order of magnitude suppression compared with previous estimates. {copyright} {ital 1997} {ital The American Physical Society}

Quark-parton model from dual topological unitarization

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

Cohen-Tannoudji, G.; El Hassouni, A.; Kalinowski, J.

1979-06-01

Topology, which occurs in the topological expansion of quantum chromodynamics (QCD) and in the dual topological unitarization (DTU) schemes, allows us to establish a quantitative correspondence between QCD and the dual S-matrix approaches. This topological correspondence, proposed by Veneziano and made more explicit in a recent paper for current-induced reactions, provides a clarifying and unifying quark-parton interpretation of soft inclusive processes. Precise predictions for inclusive cross sections in hadron-hadron collisions, structure functions of hadrons, and quark fragmentation functions including absolute normalizations are shown to agree with data. On a more theoretical ground the proposed scheme suggests a new approach tomore » the confinement problem.« less

Tachyon condensation and quark mass in the modified Sakai-Sugimoto model

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

Dhar, Avinash; High Energy Accelerator Research Organization; Nag, Partha

2008-09-15

This paper continues the investigation of the modified Sakai-Sugimoto model proposed previously [J. High Energy Phys. 01 (2008) 055]. Here we discuss in detail numerical solutions to the classical equations for the brane profile and the tachyon condensate. An ultraviolet cutoff turns out to be essential because the numerical solutions tend to rapidly diverge from the desired asymptotic solutions, beyond a sufficiently large value of the holographic coordinate. The required cutoff is determined by the non-normalizable part of the tachyon and is parametrically far smaller than that dictated by consistency of a description in terms of ten-dimensional bulk gravity. Wemore » had argued [J. High Energy Phys. 01 (2008) 055] that the solution in which the tachyon field goes to infinity at the point where the brane and antibrane meet has only one free parameter, which may be taken to be the asymptotic brane-antibrane separation. Here we present numerical evidence in favor of this observation. We also present evidence that the non-normalizable part of the asymptotic tachyon solution, which is identified with quark mass in the QCD-like boundary theory, is determined by this parameter. We show that the normalizable part of the asymptotic tachyon solution determines the quark condensate, but this requires holographic renormalization of the on-shell boundary brane action because of the presence of infinite cutoff-dependent terms. Our renormalization scheme gives an exponential dependence on the cutoff to the quark mass. We also discuss meson spectra in detail and show that the pion mass is nonzero and satisfies the Gell-Mann-Oakes-Renner relation when a small quark mass is switched on.« less

RK and RK* beyond the standard model

NASA Astrophysics Data System (ADS)

Hiller, Gudrun; Nišandžić, Ivan

2017-08-01

Measurements of the ratio of B →K*μ μ to B →K*e e branching fractions, RK*, by the LHCb Collaboration strengthen the hints from previous studies with pseudoscalar kaons, RK, for the breakdown of lepton universality, and therefore the Standard Model (SM), to ˜3.5 σ . Complementarity between RK and RK* allows us to pin down the Dirac structure of the new contributions to be predominantly SM-like chiral, with possible admixture of chirality-flipped contributions of up to O (few 10 %). Scalar and vector leptoquark representations (S3,V1,V3) plus possible (S˜2,V2) admixture can explain RK ,K* via tree-level exchange. Flavor models naturally predict leptoquark masses not exceeding a few TeV, with couplings to third-generation quarks at O (0.1 ), implying that this scenario can be directly tested at the LHC.

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

NASA Astrophysics Data System (ADS)

Yao, De-Liang

2018-02-01

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

Baryon inhomogeneity generation in the quark-gluon plasma phase

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

Layek, Biswanath; Mishra, Ananta P.; Srivastava, Ajit M.

2006-05-15

We discuss the possibility of generation of baryon inhomogeneities in a quark-gluon plasma phase due to moving Z(3) interfaces. By modeling the dependence of effective mass of the quarks on the Polyakov loop order parameter, we study the reflection of quarks from collapsing Z(3) interfaces and estimate resulting baryon inhomogeneities in the context of the early universe. We argue that in the context of certain low energy scale inflationary models, it is possible that large Z(3) walls arise at the end of the reheating stage. Collapse of such walls could lead to baryon inhomogeneities which may be separated by largemore » distances near the QCD scale. Importantly, the generation of these inhomogeneities is insensitive to the order, or even the existence, of the quark-hadron phase transition. We also briefly discuss the possibility of formation of quark nuggets in this model, as well as baryon inhomogeneity generation in relativistic heavy-ion collisions.« less

Effective theory analysis for vector-like quark model

NASA Astrophysics Data System (ADS)

Morozumi, Takuya; Shimizu, Yusuke; Takahashi, Shunya; Umeeda, Hiroyuki

2018-04-01

We study a model with a down-type SU(2) singlet vector-like quark (VLQ) as a minimal extension of the standard model (SM). In this model, flavor-changing neutral currents (FCNCs) arise at tree level and the unitarity of the 3× 3 Cabibbo-Kobayashi-Maskawa (CKM) matrix does not hold. In this paper, we constrain the FCNC coupling from b\\rArr s transitions, especially B_s\\rArr μ^+μ^- and \\bar{B}\\rArr X_sγ processes. In order to analyze these processes we derive an effective Lagrangian that is valid below the electroweak symmetry breaking scale. For this purpose, we first integrate out the VLQ field and derive an effective theory by matching Wilson coefficients up to one-loop level. Using the effective theory, we construct the effective Lagrangian for b\\rArr sγ^{(*)}. It includes the effects of the SM quarks and the violation of CKM unitarity. We show the constraints on the magnitude of the FCNC coupling and its phase by taking account of the current experimental data on Δ M_{B_s}, Br[B_s\\rArrμ^+μ^-], Br[\\bar{B}\\rArr X_sγ], and CKM matrix elements, as well as theoretical uncertainties. We find that the constraint from Br[B_s\\rArrμ^+μ^-] is more stringent than that from Br[\\bar{B}\\rArr X_sγ]. We also obtain a bound for the mass of the VLQ and the strength of the Yukawa couplings related to the FCNC coupling of the b\\rArr s transition. Using the CKM elements that satisfy the above constraints, we show how the unitarity is violated on the complex plane.

Weak Interaction Models with New Quarks and Right-handed Currents

DOE R&D Accomplishments Database

Wilczek, F. A.; Zee, A.; Kingsley, R. L.; Treiman, S. B.

1975-06-01

We discuss various weak interaction issues for a general class of models within the SU(2) x U(1) gauge theory framework, with special emphasis on the effects of right-handed, charged currents and of quarks bearing new quantum numbers. In particular we consider the restrictions on model building which are imposed by the small KL - KS mass difference and by the .I = = rule; and we classify various possibilities for neutral current interactions and, in the case of heavy mesons with new quantum numbers, various possibilities for mixing effects analogous to KL - KS mixing.

On the decays of d *(2380) in a constituent chiral quark model

NASA Astrophysics Data System (ADS)

Dong, Yubing; Huang, Fei; Shen, Pengnian; Zhang, Zongye

2017-10-01

After summarizing the experimental results and present status of the d *(2380) observed at WASA@COSY, two “extreme” models for explaining its structure, a compact hexaquark dominated model and a loose ΔΔ‧-D 12 π model, are briefly discussed, especially the former. By comparing their results with the corresponding data, the differences of the two models are addressed. As a remedy for the latter model, a mixing model and its result are also quoted for a comparison. It is shown that the compact hexaquark dominated structure might be more promising. However, the mixing model is also a possible structure, and more accurate Γ d *→NNπ data are needed for confirmation. Supported by National Natural Science Foundation of China (11475192, 11475181, 11521505, 11565007, 11635009), fund provided to the Sino-German CRC 110 “Symmetries and the Emergence of Structure in QCD” project by NSFC (11621131001), the IHEP Innovation Fund (Y4545190Y2) and F. Huang is grateful for the support of the Youth Innovation Promotion Association of CAS (2015358)

Warm stellar matter within the quark-meson-coupling model

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

Panda, P. K.; Providencia, C.; Menezes, D. P.

2010-10-15

In the present article, we investigate stellar matter obtained within the quark-meson-coupling (QMC) model for fixed temperature and with the entropy of the order of 1 or 2 Boltzmann units per baryon for neutrino-free matter and matter with trapped neutrinos. A new prescription for the calculation of the baryon effective masses in terms of the free energy is used. Comparing the results of the present work with those obtained from the nonlinear Walecka model, smaller strangeness and neutrino fractions are predicted within QMC. As a consequence, QMC has a smaller window of metastability for conversion into a low-mass blackhole duringmore » cooling.« less

Isotope chirality in long-armed multifunctional organosilicon ("Cephalopod") molecules.

PubMed

Barabás, Béla; Kurdi, Róbert; Zucchi, Claudia; Pályi, Gyula

2018-07-01

Long-armed multifunctional organosilicon molecules display self-replicating and self-perfecting behavior in asymmetric autocatalysis (Soai reaction). Two representatives of this class were studied by statistical methods aiming at determination of probabilities of natural abundance chiral isotopomers. The results, reported here, show an astonishing richness of possibilities of the formation of chiral isotopically substituted derivatives. This feature could serve as a model for the evolution of biological chirality in prebiotic and early biotic stereochemistry. © 2018 Wiley Periodicals, Inc.

Quark-hadron duality in lepton scattering off nucleons

NASA Astrophysics Data System (ADS)

Graczyk, Krzysztof M.

2010-03-01

Quark-hadron (QH) duality in lepton scattering off nucleons is studied with the resonance quark model. It is shown that in the case of neutrino scattering off an isoscalar target the duality is simultaneously observed for charged and neutral currents xF1νN, F2νN, and xF3νN weak structure functions. We demonstrate that the QH duality can be a useful property for modeling structure functions in the so-called resonance region. As an example it is shown that combining relativistic quark model predictions with duality arguments allows a construction of the inclusive resonance F2ep structure function.

Light-quarks Yukawa couplings and new physics in exclusive high- p T Higgs boson + jet and Higgs boson + b -jet events

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

Cohen, Jonathan; Bar-Shalom, Shaouly; Eilam, Gad

We suggest that the exclusivemore » $$\\mathrm{Higgs}+\\text{light}$$ (or b)-jet production at the LHC, $$pp{\\rightarrow}h+j({j}_{b})$$, is a rather sensitive probe of the light-quarks Yukawa couplings and of other forms of new physics (NP) in the Higgs-gluon $hgg$ and quark-gluon $qqg$ interactions. We study the Higgs $${p}_{T}$$-distribution in $$pp{\\rightarrow}h+j({j}_{b}){\\rightarrow}{\\gamma}{\\gamma}+j({j}_{b})$$, i.e., in $$h+j({j}_{b})$$ production followed by the Higgs decay $$h{\\rightarrow}{\\gamma}{\\gamma}$$, employing the ($${p}_{T}$$-dependent) signal strength formalism to probe various types of NP which are relevant to these processes and which we parametrize either as scaled Standard Model (SM) couplings (the kappa-framework) and/or through new higher dimensional effective operators (the SMEFT framework). We find that the exclusive $$h+j({j}_{b})$$ production at the 13 TeV LHC is sensitive to various NP scenarios, with typical scales ranging from a few TeV to $$\\mathcal{O}(10)\\text{ }\\text{ }\\mathrm{TeV}$$, depending on the flavor, chirality and Lorentz structure of the underlying physics.« less