18827525
Thermodynamics of two-color QCD and the Nambu Jona-Lasinio model
We investigate two-flavor and two-color QCD at finite temperature and chemical potential in comparison with a corresponding Nambu and Jona-Lasinio model. By minimizing the thermodynamic potential of the system, we confirm that a second-order phase transition occurs at a value of the chemical potential equal to half the mass of the chiral Goldstone mode. For chemical potentials beyond this value the scalar diquarks undergo Bose condensation and the diquark condensate is nonzero. We evaluate the behavior of the chiral condensate, the diquark condensate, the baryon charge density and the masses of scalar diquark, antidiquark and pion, as functions of the chemical potential. Very good agreement is found with lattice QCD (N{sub c}=2) results. We also compare with a model based on leading-order chiral effective field theory.
119587655
A field theoretical model for QCD thermodynamics
The PNJL model is used to study the thermodynamics of N f = 2 quark flavours interacting through chiral four-point couplings and propagating in a homogeneous Polyakov loop background. The input is fixed exclusively by selected pure-gauge lattice QCD results and by pion properties in vacuum. We present successful comparisons with lattice QCD thermodynamics expanded to finite chemical potential μq. Quark number susceptibilities at finite quark chemical potential are investigated. The validity of the Taylor expansion is then examined through a comparison between the full and truncated PNJL model calculations.
16607491
The NJL model and strange quark matter
The stability of strange-quark matter is studied within the Nambu Jona-Lasinio model with three different parameter sets. The model Lagrangian contains 4-fermion (with and without vector interaction) and 6-fermion terms; the minimum energy per baryon number as a function of the strangeness fraction of the system is compared to the masses of hyperons having the same strangeness fraction, and coherently calculated in the same version of the model, and for the same parameter set. The results show that in none of the different parameter sets strangelets are stable, and in some cases a minimum in the energy per baryon does not even exist.
15026810
Stability of strange quark matter: MIT bag versus color dielectric model
Abstract We discuss the properties of strange matter, in particular the minimum of the energy per baryon number as a function of the strangeness fraction. We utilize both the MIT bag model and the color dielectric model and compare the energy per baryon with the masses of hyperons having the corresponding strangeness fraction, which are coherently calculated within both models. We also take into account the perturbative exchange of gluons. The results obtained in the two approaches allow to discuss the stability of strangelets. While the MIT bag model and the double minimum version of the color dielectric model allow the existence of strangelets, the single minimum version of the color dielectric model excludes this possibility.
118664612
N_f=2+1 flavour equation of state
We conclude our investigation on the QCD equation of state (EoS) with 2+1 staggered flavors and one-link stout improvement. We extend our previous study [JHEP 0601:089 (2006)] by choosing even finer lattices. These new results [for details see arXiv:1007.2580] support our earlier findings. Lattices with N_t=6,8 and 10 are used, and the continuum limit is approached by checking the results at N_t=12. A Symanzik improved gauge and a stout-link improved staggered fermion action is taken; the light and strange quark masses are set to their physical values. Various observables are calculated in the temperature (T) interval of 100 to 1000~MeV. We compare our data to the equation of state obtained by the "hotQCD" collaboration.
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.
118567905
Large spin expansion of the wrapping correction to Freyhult-Rej-Zieme twist operators
Twist operators in the closed $ \mathfrak{s}\mathfrak{l}(2) $ sector of planar $ \mathcal{N} = 4 $ SYM are characterized by their spin. The explicit dependence of anomalous dimensions on this important parameter is a source of interesting information. Wrapping corrections are a non trivial part of the calculation and are under control in the framework of thermodynamical Bethe Ansatz valid for the full theory and thoroughly checked in that sector. The extension to more general twist operators beyond $ \mathfrak{s}\mathfrak{l}(2) $ has been recently accomplished for the so-called 3-gluon operators that are a special case of the generalized twist operators introduced by Freyhult, Rej and Zieme. Such operators are dual to spinning strings configurations with two spins S1, S2 in AdS5 and charge in S5. We compute the expansion of the weak-coupling leading order wrapping correction in the gauge theory limit dual to large S1 and fixed S2. We present a simple algorithm for the calculation and provide explicit results illustrating the general structure of the expansion.