Bag model of hadrons, dual QCD thermodynamics and Quark-Gluon Plasma

Abstract

Using the grand canonical ensemble formulation of a multi-particle statistical system, the thermodynamical description of the dual QCD has been presented in terms of the bag model of hadrons and analyzed for the quark-gluon plasma phase of hadronic matter. The dual QCD bag construction has been shown to lead to the radial pressure on the bag surface in terms of the vector glueball masses of the magnetically condensed QCD vacuum. Constructing the grand canonical partition function to deal with the quark-gluon plasma phase of the non-strange hadrons, the energy density and the plasma pressure have been derived and used to understand the dynamics of the associated phase transition. The critical temperature for QGP-hadron phase transition has been derived and numerically estimated by using various thermodynamic considerations. A comparison of the values of the critical temperatures for QGP-hadron phase transition with those obtained for the deconfinement-phase transition, has been shown to lead to the relaxation of the system via a mixed phase of QGP and hot hadron gas. The associated profiles of the normalized energy density and the specific heat have been shown to lead to a huge latent heat generation and indicate the onset of a first-order QGP phase transition. The squared speed of sound has been shown to act as a physical measure of large thermodynamical fluctuations near transition point where it shows a large reduction in its value as compared to the conformal limit and has intimate connection with the evolution of fire-ball and QGP in heavy-ion collision events. The possible implications of the trace anomaly and conformal measure on QGP formation have been discussed and a considerable increase in the degrees of freedom and the associated interaction effects has been indicated around the transition region and discussed for its relevance with the modern heavy-ion collision experiments.