Comment on Chernavskaya's Paper ``Double Phase Transition Model and the Problem of Entropy and Baryon Number Conservation" hep-ph/9701265

In the standard construction of a first-order equilibrium phase transition via the Gibbs criteria from a quark-gluon plasma (QGP) to a hot and dense hadron gas (HG), the appearance of a discontinuity in the entropy per baryon ratio (s/n) makes the phase transition at fixed temperature T and fixed chemical potential μ irreversible. Recently several papers have been addressed to the question of conserving the entropy per baryon s/n across the phase boundary. Leonidov et al. [1] have proposed a bag model equation of state (EOS) for the QGP consisting of massless, free gas of quarks and gluons using a (μ, T) dependent bag constant B(μ, T ) in an isentropic equilibrium phase transition from a QGP to the HG at a constant T and μ. Later Patra and Singh [2] have extended this idea to remedy some anomalous behaviour of such a bag constant B(μ, T ) through the inclusion of perturbative QCD corrections in the EOS for QGP. They have also explored the consequences of such a bag constant on the deconfining phase transition in the relativistic heavy-ion collisions as well as in the early Universe case [3]. The above mentioned analysis refers only to the stationary systems. But in the context of modern experiments on ultrarelativistic heavy-ion collisions, the dynamical evolution of the system within the framework of hydrodynamical models has to be incorporated E-mail: bkpatra@iopb.stpbh.soft.net