What do lattice baryonic susceptibilities tell us about quarks, diquarks and baryons at $T>Tc$?

Abstract

Lattice data on QCD thermodynamics, especially recent study of high order susceptibilities by UK-Bielefeld collaboration, have provided valuable information about matter properties around and above the critical temperature $T_c$. In this work we tried to understand what physical picture would explain these numerical data. We found two scenarios which will do it: (i) a quark quasiparticle gas, with the effective mass which is strongly $decreasing$ near the phase boundary into the QGP phase; or (ii) a picture including baryons at $T>T_c$, with the mass rapidly $increasing$ across the phase boundary toward QGP. We further provide several arguments in favor of the latter scenario, one of which is a natural continuity with the baryon gas picture at $T<T_c$.