A. Jakovac

The QCD equation of state with dynamical quarks

The present paper concludes our investigation on the QCD equation of state with 2 + 1 staggered flavors and one-link stout improvement. We extend our previous study [JHEP01 (2006) 089] by choosing even finer lattices. Lattices with Nt=6, 8 and 10 are used, and the continuum limit is approached by checking the results at Nt= 12. A Symanzik improved gauge and a stout-link improved staggered fermion action is utilized. We use physical quark masses, that is, for the lightest staggered pions and kaons we fix the mπ/fK and mK/fK ratios to their experimental values. The pressure, the interaction measure, the energy and entropy density and the speed of sound are presented as functions of the temperature in the range 100 ... 1000MeV. We give estimates for the pion mass dependence and for the contribution of the charm quark. We compare our data to the equation of state obtained by the “hotQCD” collaboration.

Quarkonium correlators and spectral functions at zero and finite temperature

We study quarkonium correlators and spectral functions at zero and finite temperature using the anisotropic Fermilab lattice formulation with anisotropy {xi}=2 and 4. To control cut-off effects we use several different lattice spacings. The spectral functions were extracted from lattice correlators with maximum entropy method based on a new algorithm. We find evidence for the survival of 1S quarkonium states in the deconfined medium till relatively high temperatures as well as for dissolution of 1P quarkonium states right above the deconfinement temperature.

Power-Law Tails from Multiplicative Noise

We show that the well-known linear Langevin equation, modeling the Brownian motion and leading to a Gaussian stationary distribution of the corresponding Fokker-Planck equation, is changed by the smallest multiplicative noise. This leads to a power-law tail of the distribution for sufficiently large momenta. At finite ratio of the correlation strength for the multiplicative and the additive noises the stationary energy distribution becomes exactly the Tsallis distribution.

Hierarchy of effective field theories of hot electroweak matter

A hierarchy of effective three-dimensional theories of finite temperature electroweak matter is studied. First an integration over nonstatic modes leads to an effective theory containing a gauge field [ital A][sub [ital i]][sup [ital a]], an adjoint Higgs field [ital A][sub 0][sup [ital a]], and the fundamental Higgs field [phi][sub [alpha]]. We carry out the integration in the one-loop approximation, study renormalization effects, and estimate quantitatively those terms of the effective action which are suppressed by inverse powers of the temperature. Second, because of the existence of well-separated thermal mass scales, [ital A][sub 0][sup [ital a]] can be integrated over, and finally also [phi][sub [alpha]], leaving an effective theory of the [ital A][sub [ital i]][sup [ital a]]. In the analysis of the subsequent models particular attention is paid to the screening of the magnetic fluctuations due to the integrated-out degrees of freedom.

Classical statistical mechanics and Landau damping

Abstract We study the retarded response function in scalar φ4-theory at finite temperature. We find that in the high-temperature limit the imaginary part of the self-energy is given by the classical theory to leading order in the coupling. In particular the plasmon damping rate is a purely classical effect to leading order, as shown by Aarts and Smit. The dominant contribution to Landau damping is given by the propagation of classical fields in a heat bath of non-interacting fields.

Electroweak phase transition in the minimal supersymmetric standard model: 4-dimensional lattice simulations

Recent lattice results have shown that there is no Standard Model (SM) electroweak phase transition (EWPT) for Higgs boson masses above ≈ 72 GeV, which is below the present experimental limit. According to perturbation theory and 3-dimensional (3d) lattice simulations there could be an EWPT in the Minimal Supersymmetric Standard Model (MSSM) that is strong enough for baryogenesis up to mh≈105 GeV. In this letter we present the results of our large scale 4-dimensional (4d) lattice simulations for the MSSM EWPT. We carried out infinite volume and continuum limits and found a transition whose strength agrees well with perturbation theory, allowing MSSM electroweak baryogenesis at least up to mh = 103 ± 4 GeV. We determined the properties of the bubble wall that are important for a successful baryogenesis.

Partial path integration of quantum fields: Two loop analysis of the SU(2) gauge Higgs model at finite temperature

Abstract High temperature reduction of the SU(2) Higgs model is realised by partially integrating its partition function. Various approximate forms of the effective theory resulting from the integration over non-static fields and the static electric potential are analysed. Also non-polynomial and non-local terms are allowed. Consistency of the perturbative solution is ensured by new types of induced counterterms. Perturbative phase transition characteristics are presented in the Higgs mass range 30–120 GeV, and compared to results of other perturbative approaches.

A non-conventional description of quark matter

We point out that in a simple model with multiplicative noise non-Boltzmann-Gibbs distributions with power-law tail arise as stationary solutions. We compare it to hadronic transverse momentum distributions at RHIC energies and consider average properties of a non-conventional quark matter with Tsallis distribution at the instant of hadronization.

Non-Gaussian fixed points in fermionic field theories without auxiliary Bose fields

The functional equation governing the renormalization flow of fermionic field theories is investigated in