Gwendolyn Lacroix

Comments on Yang–Mills thermodynamics: The Hagedorn spectrum and the gluon gas pictures for a generic gauge algebra

Abstract We discuss the dependence of pure Yang–Mills equation of state on the choice of gauge algebra. In the confined phase, we generalize to an arbitrary simple gauge algebra Meyerʼs proposal of modeling the Yang–Mills matter by an ideal glueball gas in which the high-lying glueball spectrum is approximated by a Hagedorn spectrum of closed-bosonic-string type. Such a formalism is undefined above the Hagedorn temperature, corresponding to the phase transition toward a deconfined state of matter in which gluons are the relevant degrees of freedom. Under the assumption that the renormalization scale of the running coupling is gauge-algebra independent, we discuss about how the behavior of thermodynamical quantities such as the trace anomaly should depend on the gauge algebra in both the confined and deconfined phase. The obtained results compare favorably with recent and accurate lattice data in the su ( 3 ) case and support the idea that the more the gauge algebra has generators, the more the phase transition is of first-order type.

Glueballs and the Yang-Mills plasma in a

The strongly coupled phase of Yang-Mills plasma with arbitrary gauge group is studied in a T-matrix approach. The existence of lowest-lying glueballs, interpreted as bound states of two transverse gluons (quasi-particles in a many-body set up), is analyzed in a non-perturbative scattering formalism with the input of lattice-QCD static potentials. Glueballs are actually found to be bound up to 1.3 Tc. Starting from the T-matrix, the plasma equation of state is computed by resorting to Dashen, Ma and Bernstein’s formulation of statistical mechanics and favorably compared to quenched lattice data. Special emphasis is put on SU(N) gauge groups, for which analytical results can be obtained in the large-N limit, and predictions for a G2 gauge group are also given within this work.

T

The thermodynamic properties of

-matrix approach

{\cal N}=1

The SUSY Yang-Mills plasma in a

supersymmetric Yang-Mills theory with an arbitrary gauge group are investigated. In the confined range, we show that identifying the bound state spectrum with a Hagedorn one coming from non-critical closed superstring theory leads to a prediction for the value of the deconfining temperature

T

T_c

-matrix approach

that agrees with recent lattice data. The deconfined phase is studied by resorting to a

Thermodynamics of the Quark-Gluon Plasma within a T-matrix approach

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Large-NcPolyakov–Nambu–Jona-Lasinio model with explicitZNcsymmetry

-matrix formulation of statistical mechanics in which the medium under study is seen as a gas of quasigluons and quasigluinos interacting nonperturbatively. Emphasis is put on the temperature range (1-5)~

Lagrange-mesh calculations in momentum space.

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