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

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

Coupled Gap Equations for the Screening Masses in Hot SU(N) Gauge Theory

Coupled 1-loop gap equations are studied numerically for non-Abelian electric and magnetic screening in various versions of the three-dimensional effective gauge models. Corrections due to higher dimensional and non-local operators are assessed quantitatively. Comparison with numerical Monte-Carlo investigations suggests that quantitative understanding beyond the qualitative features can be achieved only by going beyond the present treatment.Comment: 15 pages, Latex, 4 eps figures included, uses epsf.sty, added references, corrected typo

Finite temperature spectral function of the σ\sigma meson from large N expansion

The spectral function of the scalar-isoscalar channel of the O(N) symmetric linear $\sigma$ model is studied in the broken symmetry phase. The investigation is based on the leading order evaluation of the self-energy in the limit of large number of Goldstone bosons. We describe its temperature dependent variation in the whole low temperature phase. This variation closely reflects the trajectory of the scalar-isoscalar quasiparticle pole. In the model with no explicit chiral symmetry breaking we have studied near the critical point also the corresponding dynamical exponent.Comment: 9 pages, 3 figures. To be published in Proc. of Budapest'02 Workshop on Quark and Hadron Dynamics, Budapest, Hungary, March 3--7, 200

Analytic determination of the T-\mu phase diagram of the chiral quark model

Using a gap equation for the pion mass a nonperturbative method is given for solving the chiral quark-meson model in the chiral limit at the lowest order in the fermion contributions encountered in a large N_f approximation. The location of the tricritical point is analytically determined. A mean field potential is constructed from which critical exponents can be obtained.Comment: 8 pages, 2 figures. To be published in Proc.of Budapest'04 Workshop on Hot and Dense Matter in Relativistic Heavy Ion Physics, Budapest, Hungary, March 24-27, 200