Agam K. Jha

Effect of curvature on a statistical model of quark-gluon-plasma fireball in the hadronic medium

The free energy of a quark-gluon plasma fireball in the hadronic medium is calculated in the Ramanathan et al statistical model after incorporating the effect of curvature. The result with the inclusion of curvature is found to produce significant improvements in all the parameters we calculated with respect to the earlier results. The surface tension with this curvature effect is found to be 0.17Tc3, which is two times the earlier value of surface tension which is 0.078Tc3, and this new result is nearly close to the lattice value 0.24Tc3. As far as transition is concerned, a thermodynamic variable like entropy shows weakly first-order phase transition and it shows continuity in the behaviour of specific heat.

Effect of finite chemical potential on QGP-Hadron phase transition in a statistical model of fireball formation

We study the effect of finite chemical potential for the QGP constituents in the Ramanathan et al. statistical model [Phys. Rev.C70, 027903, (2004)]. While the earlier computations using this model with vanishing chemical potentials indicated a weakly first order phase transition for the system in the vicinity of 170 MeV [Pramana68 757 (2007)], the introduction of finite values for the chemical potentials of the constituents makes the transition a smooth roll over of the phases, while allowing fireball formation with radius of a few ‘fermi’ to take place. This seems to be in conformity with the latest consensus on the nature of the QGP-Hadron phase transition.

A Density of States for QGP Fireball Formation in Heavy Ion Collisions Incorporting Hydrodynamical Features in the Model

We propose a model density of states for characterizing the quarks and gluons in a Quark–Gluon Plasma (QGP) fireball, incorporating the hydrodynamic features expected in a plasma with a shear viscosity parameter. We compute the thermodynamic quantities of a quasi-equilibrium system of QGP and hadrons resulting from heavy ion collisions process and make a comparision with lattice QCD calculations of similar quantities, particularly with the \(\frac{\eta }{s}\) ratio, where ’\(\eta \)’ is the shear viscosity of the QGP plasma and ’s’ is its entropy density. We present feasible bounds on this important ratio which may be determined in ongoing URHIC experiments.