53408656
Fluctuations of conserved charges at finite temperature from lattice QCD
A bstractWe present the full results of the Wuppertal-Budapest lattice QCD collaboration on flavor diagonal and non-diagonal quark number susceptibilities with 2 + 1 staggered quark flavors, in a temperature range between 125 and 400 MeV. The light and strange quark masses are set to their physical values. Lattices with Nt = 6, 8, 10, 12, 16 are used. We perform a continuum extrapolation of all observables under study. A Symanzik improved gauge and a stout-link improved staggered fermion action is utilized. All results are compared to the Hadron Resonance Gas model predictions: good agreement is found in the temperature region below the transition.
15445984
Evaporation of the gluon condensate: a model for pure gauge SU(3)c phase transition
Abstract We interpret lattice data for the equation of state of pure gauge SU (3) c by an evaporation model. At low temperatures gluons are frozen inside the gluon condensate, whose dynamics is described in terms of a dilaton Lagrangian. Above the critical temperature quasi-free gluons evaporate from the condensate: a first order transition is obtained by minimizing the thermodynamical potential of the system. Within the model it is possible to reproduce lattice QCD results at finite temperature for thermodynamical quantities such as pressure and energy. The gluonic longitudinal mass can also be evaluated; it vanishes below the critical temperature, where it shows a discontinuity. At very large temperatures we recover the perturbative scenario and gluons are the only asymptotic degrees of freedom.
55793321
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.
56465034
The chiral and deconfinement crossover transitions: PNJL model beyond mean field ∗
Abstract The Polyakov loop extended Nambu and Jona-Lasinio model (PNJL model) in a mean field framework shows astonishingly good agreement with lattice QCD calculations which needs to be better understood. The present work reports on further developments concerning both Polyakov loop and mesonic fluctuations beyond mean field approximation. Corrections beyond mean field are of special interest for the thermal expectation values of the Polyakov loop 〈 Φ 〉 and its conjugate 〈 Φ ∗ 〉 , which differ once the quark chemical potential is non-zero. Mesonic fluctuations are also considered with emphasis on the role of pionic modes.
14960863
Polyakov loop, diquarks, and the two-flavor phase diagram
An updated version of the PNJL model is used to study the thermodynamics of N{sub f}=2 quark flavors interacting through chiral four-point couplings and propagating in a homogeneous Polyakov loop background. Previous PNJL calculations are extended by introducing explicit diquark degrees of freedom and an improved effective potential for the Polyakov loop field. The mean field equations are treated under the aspect of accommodating group theoretical constraints and issues arising from the fermion sign problem. The input is fixed exclusively by selected pure-gauge lattice QCD results and by pion properties in vacuum. The resulting (T,{mu}) phase diagram is studied with special emphasis on the critical point, its dependence on the quark mass and on Polyakov loop dynamics. We present successful comparisons with lattice QCD thermodynamics expanded to finite chemical potential {mu}.
119349228
Stability of strange quark matter in the MIT bag model and in the Color Dielectric Model
We utilize the MIT bag model and two different versions of the Color Dielectric Model in order to study the properties of strange matter, and to discuss the stability of strangelets. We also investigate the effect of the introduction of perturbative gluons. The MIT bag model and the Double Minimum version of the Color Dielectric Model allow the existence of strangelets, while the Single Minimum version excludes this possibility.
122501875
On marginally deformed meson spectroscopy
We review the results of 0710.4292 [hep-th] where we study the embedding of spacetime filling D7-branes in β-deformed backgrounds. This corresponds to flavoring β-deformed = 4 super Yang–Mills. For the supersymmetric and the more general non-supersymmetric three parameter deformations, we study quadratic fluctuations of a probe D7-brane wrapped on a deformed three-sphere, which correspond to mesonic configurations of the dual field theory. We manage to solve their equations exactly in the presence of a non-trivial coupling between scalar and vector modes induced by the deformation. We find a mesonic mass spectrum which is discrete, with a mass gap and a Zeeman-like splitting occurs.