Influence of the isospin and hypercharge chemical potentials on the location of the CEP in the mu_B-T phase diagram of the SU(3)_L x SU(3)_R chiral quark model

We investigate the influence of the asymmetric quark matter (rho_u\ne rho_d\ne rho_s) on the mass of the quasiparticles and the phase diagram of the chiral quark model parametrized at one-loop level of the renormalized theory, using the optimized perturbation theory for the resummation of the perturbative series. The effect of various chemical potentials introduced in the grand canonical ensemble is investigated with the method of relativistic many-body theory. The temperature dependence of the topological susceptibility is estimated with the help of the Witten-Veneziano mass formula.Comment: RevTeX4, 13 pages, 6 figures, version accepted for publication in Phys. Rev.

Influence of the Polyakov loop on the chiral phase transition in the two flavor chiral quark model

The SU(2)_L x SU(2)_R chiral quark model consisting of the (sigma,pi) meson multiplet and the constituent quarks propagating on the homogeneous background of a temporal gauge field is solved at finite temperature and quark baryon chemical potential mu_q using an expansion in the number of flavors N_f, both in the chiral limit and for the physical value of the pion mass. Keeping the fermion propagator at its tree-level, several approximations to the pion propagator are investigated. These approximations correspond to different partial resummations of the perturbative series. Comparing their solution with a diagrammatically formulated resummation relying on a strict large-N_f expansion of the perturbative series one concludes that only when the local part of the approximated pion propagator resums infinitely many orders in 1/N_f of fermionic contributions a sufficiently rapid crossover transition at mu_q=0 is achieved allowing for the existence of a tricritical point or a critical end point in the mu_q-T phase diagram. The renormalization and the possibility of determining the counterterms in the resummation provided by a strict large-N_f expansion are investigated.Comment: 20 pages, 7 figures, 5 graphs, and 3 tables; uses revtex4-1, minor corrections and investigation of the influence of the pion-fermion setting-sun integral on the field equations for the Polyakov loop and its conjugate. Version published in the Phys. Rev. D journa

Beyond HTL: The Classical Kinetic Theory of Landau Damping for Selfinteracting Scalar Fields in the Broken Phase

The effective theory of low frequency fluctuations of selfinteracting scalar fields is constructed in the broken symmetry phase. The theory resulting from integrating fluctuations with frequencies much above the spontanously generated mass scale $(p_0>>M)$ is found to be local. Non-local dynamics, especially Landau damping emerges under the effect of fluctuations in the $p_0 \sim M$ region. A kinetic theory of relativistic scalar gas particles interacting via their locally variable mass with the low frequency scalar field is shown to be equivalent to this effective field theory for scales below the characteristic mass, that is beyond the accuracy of the Hard Thermal Loop (HTL) approximation.Comment: 5 pages, Latex, uses sprocl.sty, to be published in the Proceedings of SEWM 98 Conference Copenhagen, Denmark 2-5 December 199

The effect of the Polyakov loop on the chiral phase transition

The Polyakov loop is included in the SU(2)_L x SU(2)_R chiral quark-meson model by considering the propagation of the constituent quarks, coupled to the (sigma,pi) meson multiplet, on the homogeneous background of a temporal gauge field, diagonal in color space. The model is solved at finite temperature and quark baryon chemical potential both in the chiral limit and for the physical value of the pion mass by using an expansion in the number of flavors N_f. Keeping the fermion propagator at its tree-level, a resummation on the pion propagator is constructed which resums infinitely many orders in 1/N_f, where O(1/N_f) represents the order at which the fermions start to contribute in the pion propagator. The influence of the Polyakov loop on the tricritical or the critical point in the mu_q-T phase diagram is studied for various forms of the Polyakov loop potential.Comment: 8 pages, 3 figures, uses svepjCONF.clo, contribution to the International Workshop on Hot & Cold Baryonic Matter 2010, 15-20 August, Budapest, Hungar

Effect of the scalar condensate on the linear gauge field response in the Abelian Higgs model

The effective equations of motion for low-frequency mean gauge fields in the Abelian Higgs model are investigated in the presence of a scalar condensate, near the high temperature equilibrium. We determine the current induced by an inhomogeneous background gauge field in the linear response approximation up to order $e^4$, assuming adiabatic variation of the scalar fields. The physical degrees of freedom are found and a physical gauge choice for the numerical study of the combined Higgs+gauge evolution is proposed.Comment: 11 pages, latex, no figure

The scalar-isoscalar spectral function of strong matter in a large N approximation

The enhancement of the scalar-isoscalar spectral function near the two-pion threshold is studied in the framework of an effective linear $\sigma$ model, using a large N approximation in the number of the Goldstone bosons. The effect is rather insensitive to the detailed T=0 characteristics of the $\sigma$ pole, it is accounted by a pole moving with increasing $T$ along the real axis of the second Riemann sheet towards the threshold location from below.Comment: 5 pages, poster presented at SEWM2002, Heidelberg, October 200

Sensitivity of the chiral phase transition of QCD to the scalar meson sector

Gribov's theory of light quark confinement implies the existence of two kinds of scalar bound states. The phase diagram of the three-flavor QCD is mapped out in the (m_pi-m_K)-plane with help of the SU_L(3)xSU_R(3) linear sigma model supplemented with the assumption that the masses of the so-called superbound scalars do not change under the variation of the pion and kaon mass. The phase boundary along the m_pi=m_K line is found in the interval 15 MeV<m_crit<25 MeV, irrespective which f_0-sigma linear combination is identified with the pure superbound state.Comment: 11 pages, 3 figures, presented at the Gribov-75 Memorial Workshop on Quarks, Hadrons, and Strong Interactions, Budapest, Hungary, 22-24 May 200

Coupled gap equations for the screening masses in the SU(2) Higgs model

The complete set of static screening masses is determined for the SU(2) Higgs model from one-loop coupled gap equations. Results from the version, containing scalar fields both in the fundamental and adjoint representations are compared with the model arising when the integration over the adjoint scalar field is performed. A non-perturbative and non-linear mapping between the couplings of the two models is proposed, which exhibits perfect decoupling of the heavy adjoint scalar field. Also the alternative of a gauge invariant mass resummation is investigated in the high temperature phase.Comment: 15 pages, Latex, 7 eps figures included, uses epsf.sty, minor corrections, conclusions unchange