S. Somorendro Singh

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.

Photon production in high energy nuclear collision of quark–gluon plasma

We extend to investigate photon production through annihilation with scattering (AWS), and Compton and annihilation processes from a stabilized high energy nuclear collision of quark–gluon plasma (QGP) incorporating finite value of quark mass obtained through a strong coupling value. The production rate is represented in the region of low and intermediate photon energy and it is observed to be a decreasing function with temperature. The calculation is extended to the case of photon spectra with the photon transverse momentum. The current observation shows little enhancement in both processes at the temperature T = 0.25 GeV and it is in conformity with the recent direct photon production of other works at temperature T = 0.30 GeV.

Free Energy Evolution and Photon Radiation from QGP

We investigate a simple statistical model of quark-gluon plasma (QGP) formation. In the model, we use a phenomenological parameter which enhances the growth of quark droplet formation and also stabilizes the formation of the QGP droplet. Then, we study direct photon radiation through annihilation and Compton processes from these stabilized QGP incorporating the parametrized momentum factor in the quark mass. The production rate of thermal photon is found to be dominated in the low transverse momentum and increases a little in comparison to the recent development of direct photon radiation of other theoretical and experimental works.

Direct photon production at finite chemical potential from quark–gluon plasma

We extend to calculate the direct photon production from quark–gluon plasma (QGP) considering finite chemical potential. The calculation is done from a system of strongly interacting QGP and the result is found to be increasing function of chemical potential in all the channels of photon production. It also shows enhancement of photon production from photon production without chemical potential and other theoretical calculation of direct photon productions.

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.

Curvature Effect on QGP Equation of State

We study the effect of curvature on QGP equation of state (EoS) using a simple phenomenological model. The calculation is performed using effective quark mass including the curvature term. The model results provide QGP EoS which are in good agreement with our earlier work.

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.

Rotating Boson Star Under Weak Gravity Potential

Neutron stars (NS) are one of the probable signals of early universe formation in which the quark and gluons are defined in free degree of freedom. Like NS a boson Star (BS) is formed out of particles called bosons. For the existence of stars, there must be a stable type of boson that possesses a small mass of magnitude. Such systems must be formed by perturbation of small potential under the weak gravity limit.These pattern are shown by the oscillations of BS.

Diphoton Emission from Equilibrium Quark-Gluon Plasma

Diphoton production from equilibrium quark-gluon plasma (QGP) is studied under the annihilation with Compton process. In the study we use a strong coupling modified through a one loop correction factor. Now the modification in the coupling value incorporate thermal quark mass \(m_{q}\) to obtain diphoton emission from equilibrium quark-gluon plasma. It implies that the one loop correction in the running coupling plays a pivoted role in the production of diphoton.

Oscillation of boson star in Newtonian approximation

Boson star (BS) rotation is studied under Newtonian approximation. A Coulombian potential term is added as perturbation to the radial potential of the system without disturbing the angular momentum. The results of the stationary states of these ground state, first and second excited state are analyzed with the correction of Coulombian potential. It is found that the results with correction increased in the amplitude of oscillation of BS in comparison to potential without perturbation correction.