Phase diagram of two-color QCD matter at finite baryon and axial isospin densities

We study the two-color QCD matter with two fundamental quark flavors using the chiral perturbation theory and the Nambu-Jona-Lasinio(NJL)model.The effective Lagrangian is derived in terms of mesons and baryons,i.e.diquarks.The low lying excitations lie in the extended SU(4)flavor symmetry space.We compute the leading order terms of the Lagrangian as a function of the baryon and axial isospin densities.After numerically solving the gap equations in the two-color NJL model,the phase diagram is obtained in the μ−ν5 plane.

Photon polarization tensor in a magnetized plasma system

We investigate the photon polarization tensor at finite temperatures in the presence of a static and homogeneous external magnetic field.In our scheme,the summing of the Matsubara frequency is performed after Poisson resummation,which is easily completed and converges quickly.Moreover,the behaviors of finite Landau levels are presented explicitly.It shows a convergence while summing infinite Landau levels.Consequently,there is no necessity to truncate the Landau level in a numerical estimation.At zero temperature,the lowest Landau level(LLL)approximation is analytically satisfied for the vacuum photon polarization tensor.However,we examine that the LLL approximation is not enough for the thermal polarization tensor.The thermal tensor obtains non-trivial contributions from the finite-n Landau levels.And,photon spectra gains a large imaginary contribution in thermal medium,which is the so-called Landau damping.Finally,it is argued that the summation of Matsubara frequency is not commuted with Landau level ones,such conjecture is excluded in our calculations.

Charged pion condensation in anti-parallel electromagnetic fields and nonzero isospin density

The formation of charged pion condensate in anti-parallel electromagnetic fields and in the presence of the isospin chemical potential is studied in the two-flavor Nambu-Jona-Lasinio model.The method of Schwinger proper time is extended to explore the quantities in the off-diagonal flavor space,i.e.the charged pion.In this framework,π^± are treated as bound states of quarks and not as point-like charged particles.The isospin chemical potential plays the role of a trigger for charged pion condensation.We obtain the associated effective potential as a function of the strength of the electromagnetic fields and find that it contains a sextic term which possibly induces a weak first order phase transition.The dependence of pion condensation on model parameters is investigated.