Finite temperature Landau gauge lattice quark propagator

The quark propagator at finite temperature is investigated using quenched gauge configurations. The propagator form factors are investigated for temperatures above and below the gluon deconfinement temperature $$T_c$$Tc and for the various Matsubara frequencies. Significant differences between the functional behaviour below and above $$T_c$$Tc are observed both for the quark wave function and the running quark mass. The results for the running quark mass indicate a link between gluon dynamics, the mechanism for chiral symmetry breaking and the deconfinement mechanism. For temperatures above $$T_c$$Tc and for low momenta, our results support also a description of quarks as free quasiparticles.

Study of baryon octet charge form factors in perturbative chiral quark model

The charge form factors of baryon octet are studied in the perturbative chiral quark model (PCQM). The relativistic quark wave function is extracted by fitting the theoretical results of the nucleon charge form factors to the experimental data and the predetermined quark wave function is applied to study the charge form factors of other octet baryons. The PCQM results are found, based on the predetermined quark wave function, in good agreement with the experimental data.

NON-LOCAL CHIRAL QUARK MODELS WITH POLYAKOV LOOP AT FINITE TEMPERATURE AND CHEMICAL POTENTIAL

We analyze the chiral restoration and deconfinement transitions in the framework of a non-local chiral quark model which includes terms leading to the quark wave function renormalization, and takes care of the effect of gauge interactions by coupling the quarks with the Polyakov loop. Non-local interactions are described by considering both a set of exponential form factors, and a set of form factors obtained from a fit to the mass and renormalization functions obtained in lattice calculations.

BARYON MAGNETIC MOMENTS AND SPIN DEPENDENT QUARK FORCES

The J=3/2 Δ, J=1/2 nucleon mass difference shows that quark energies can be spin dependent. It is natural to expect that quark wave functions also depend on spin. In the octet, such spin dependent forces lead to different wave functions for quarks with spin parallel or antiparallel to the nucleon spin. A two component Dirac equation wave function is used for the quarks assuming small current quark masses for the u and d quarks. Then, the neutron/proton magnetic moment ratio, the nucleon axial charge, and the spin content of the nucleon can all be simultaneously fit assuming isospin invariance between the u and d quarks, but allowing for spin dependent forces. The breakdown of the Coleman–Glashow sum rule for octet magnetic moments follows naturally in this Dirac approach as the bound quark energy also effects the magnetic moment. Empirically the bound quark energy increases with the number of strange quarks in the system. Allowing the strange quark wave function similar spin dependence predicts the magnetic moments of the octet, in close agreement with experiment. Differences between the octet and decuplet magnetic moments are also explained immediately with spin dependent wave functions.

VACUUM STRUCTURE, CHIRAL SYMMETRY BREAKING AND STATIC PROPERTIES OF OCTET AND DECUPLET BARYONS

The static properties of the octet and decuplet baryons are considered within the framework of a quark model of hadrons where the chiral symmetry is broken dynamically through a nontrivial vacuum structure. The pion and kaon being treated consistently within the model yield to the constituent quark wave function approximately same as the wave functions from the gap equations and thus determine consequently the constituent quark field operators. The model was successfully used earlier to study some hadronic phenomena and here also it estimates the static properties of the octet and decuplet baryons in a unified manner, in reasonable agreement with the available measurements. The only parameter of the model is the harmonic oscillator radius for the baryons. The method is nonperturbative with respect to the equal time algebra for the constituent quark field operators.