Effective degrees of freedom of the quark-gluon plasma

The effective degrees of freedom of the quark-gluon plasma are studied in the temperature range ∼(1-2)Tc. We show that including light bosonic states one can reproduce the pressure and energy density of the quark-gluon plasma obtained by lattice simulations. The number of the bosonic states required is at most of the order of 20, consistent with the number of light mesonic states and in disagreement with a recently proposed picture of the quark-gluon plasma as a system populated with exotic bound states. We also constrain the quark quasiparticle chiral invariant mass to be ≲300MeV. Some remarks regarding the role of the gluon condensation and the baryon number-strangeness correlation are also presented.