Quark Condensate and Nucleon-Antinucleon Phase Transition from Hadronic Models at Finite Temperature
We investigate different hadronic model parametrizations at high temperature regime. All the models were constructed to reproduce some observables at low temperature. At high temperature this study becomes important once a copious number of antiparticles arises playing an essential role in the high energy heavy-ion collision experiments like RHIC, SPS and LHC. In our study we observe a model dependent first-order phase transition at about 180 MeV. It was also verified that the order parameter, in-medium effective baryon mass, is very similar to the quark condensate as a function of the temperature. This result acquires importance since the quark condensate is the phase transition order parameter from hadronic (massive mesons) to chiral (massless mesons) phases.
We propose a simple scheme to start a parton-shower evolution description from a given jet configuration in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation events. This allows a convenient combination of the full angular information content of matrix elements with the detailed sub-jet structure of parton showers, and should give a realistic overall description of event properties. Explicit studies with this hybrid approach are presented for the four-jet case, as a simple testing ground of the ideas.