arXiv subjects

Agam K. Jha

Publications and source records attributed to Agam K. Jha.

11 recordsLinked to original sources

arXiv2026

Formation of Quark-Gluon Plasma droplets under Ultra-Relativistic Heavy Ion Collisions in the presence of magnetic fields with a modified hadronic medium

We build upon the previous studies conducted in this domain using the density of states of various components of the quark-gluon plasma(QGP) modelled after the Thomas-Fermi and Bethe models. This study provides an analysis of the stability of the quark-gluon plasma droplet by the inclusion and variation of chemical potential and magnetic field. An effective mass term is included to account for both the rest mass and thermodynamic mass terms of the quarks and gluon. We also expand on the inclusion of a different meson, kaon, into the medium of the droplet. The analysis on these quantities is done by calculating the free energy of the system and examining it as a function of droplet radius, chemical potential and magnetic field to find conditions for stable droplet formation. We discover that a kaonic medium, along with a pre-existing pionic medium, provides greater stability to the system. At the same time, it is realised that the parameters of chemical potential and magnetic field, due to their opposing effect, help in containing the droplet. Further calculations on entropy and heat capacity yield information about the nature of the phase transition of the system. Our analysis and results are in accordance with lattice QCD simulations.

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arXiv2024

Dynamics of Phase Transition in Quark-Gluon Plasma Droplet Formation under Magnetic Field

Pre-existing density of states for a Quark-Gluon Phase, based on Thomas-Fermi and Bethe mode, is expanded by incorporation of new variables. Results from recent study indicate that perturbations in the form of a finite non-zero chemical potential T, B, dynamic thermal masses M and of course Temperature T are indeed vital to fully comprehend the formation and dynamics of QGP. Simulations depict an overall increase in the stability of QGP in the paradigm of the statistical model. On the top of Free Energy, Entropy and heat capacity are calculated for the phase transition. The overall qualitative behavior, of entropy or Heat Capacity determines the order of phase transition of the QGP. Investigation of order of phase transition is carried out in this study through Monte-Carlo based differential element, which ensures the inclusion of the randomness of the collisions at the particle colliders.

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arXiv2011

A model density of states for Quarks and Gluons in QGP

We propose an algebraic form for the density of states of quarks and gluons in a Quark-Gluon Plasma (QGP) fireball in quasi-equilibrium with a hadronic medium as $ρ(k)= \frac α{k} + βk + δk^{2}$, and determine the parameters $α$, $β$ and $δ$ using Lattice Gauge results on the velocity of sound in QGP. The behaviour of the resulting $ρ(k)$ can be easily compared with the thermodynamic data on QGP that is expected from LHC and other RHIC experiments. Our numerical result shows a linear rise of the value of $ρ(k)$ for $k\sim T \approx 160 to 180 MeV$, which is significant, and throws light on the evolution of the QGP phase.

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arXiv2009

The phase structure of QGP-Hadron in a statistical model using Cornell, Richardson and Peshier potentials

We study the phase structure of the QGP-Hadron system under quasi-static equilibrium using the Ramanathan et al. statistical model for the QGP fireball formation in a hadronic medium. While in the earlier published studies we had used the Peshier effective potential which is appropriate for the deconfined QGP phase but could be extrapolated to the transition region from the higher momentum regime, in this paper we study the same system using the Cornell and Richardson potentials which are more relevant for the low momentum confinement regime, but could again be extrapolated to the transition region from below. Surprisingly, the overall picture in both the cases are quite similar with minor divergences,(though,the results with the Richardson potential shows a sizable deviation from the other two potentials), thus indicating the robustness of the model and its self-consistency. The result of our numerical results pertaining to the variation of the velocity of sound in the QGP-Hadron medium with temperature in the various scenarios considered by us, is that, the phase transition seems to be a gentle roll-over of phases rather than a sharp transition of either the first or second order, a result in conformity with recent lattice calculations, but with much less effort.

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arXiv2008

Effect of the 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 including the effect of curvature. The result with this curvature is found to produce significant improvement from earlier results in all the parameters we calculated. The surface tension with this curvature effect is found to be $ 0.17 T_{c}^{3}$, which is two times the earlier value of surface tension which is $ 0.078 T_{c}^{3} $, and it is nearly close to the lattice value $0.24 T_{c}^{3} $. The speed of sound calculated with curvature correction is still found to be smaller in comparision with the standard speed of sound in the QGP droplet.

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arXiv2006

Electromagnetic Radiation From An Equilibrium Quark -Gluon Plasma System

We study the electromagnetic radiation from a hot and slightly strong interacting fireball system of quark-gluon plasma using the Boltzmann distribution function for the incoming particles and Bose-Einstein distribution for gluon in first calculation of electromagnetic radiation and Fermi-Dirac distribution for quark, antiquark and Boltzmann distribution for gluon in our second calculation. The thermal photon emission rate is found that it is infrared divergent for massless quarks which are discussed by many authors and regulate this divergence using different cut-off in the qurak mass. However we remove this divergence using the same technique of Braaten and Pisarski in the thermal mass of the system by using our model calculation in the coupling parameter. Thus the production rate of the thermal photon is found to be smoothly worked by this cut-off technique of our model. The result is found to be matched with the most of the theoretical calculations and it is in the conformity with the experimental results of $200 AGeV$ S+Au collision of LHC.

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arXiv2006

Dilepton Production In Non-equilibriated Quark Gluon Plasma

A model of cut-off momentum distribution functions in a Quark Gluon Plasma with finite baryon chemical potential is discussed. This produces a quark gluon plasma signature in Ultra Relativistic Nuclear Collisions with a specific structure of the dilepton spectrum in the transverse momentum region of $(1-4)~GeV$ and the dilepton production rate is found to be a strong decreasing function of the chemical potential.

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arXiv2005

Thermal and interfacial properties of a Quark Gluon Plasma droplet in a hadronic medium via a statistical model

Thermal and interfacial properties of a QGP droplet in a hadronic medium are computed using a statistical model of the system. The results indicate a weakly first order transition at a transition temperature \sim (160 \pm 5) MeV. The interfacial surface tension is proportional to the cube of the transition temperaure irrespective of the magnitude of the transition temperature. The velocity of sound in the QGP droplet is predicted to be in the range (0.27 \pm 0.02) times the velocity of light in vacuum, and this value is seen to be independent of the value of the transition temperature as well as the model parameters. These predictions are in remarkable agreement with Lattice Simulation results and extant MIT Bag model predictions.

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arXiv2005

A Comparative Study of Two Models of QGP-Fireball Formation

A Comparative study of the strengths and weakness of the models of fireball formation namely the statistical model of Ramanathan et.al (Physical Review C 70, 027903, 2004) and the approximation schemes of Kapusta et. al (Physical Review D 46, 1379, 1992) and its subsequent improved variants is made. The way to complement the various approximation schemes, in order to enhance their utility in the phenomenological analysis of QGP data that are expected from ongoing URHIC experiments, is suggested. The calculations demonstrate a striking QCD behaviour of the surface tension of the QGP droplet resulting in its increase with temperature, which is due to the confining nature of QCD forces at the surface and the interface surface tension varies as the cube of the transition temperature which is in conformity with the results of Lattice QCD simulations.

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arXiv2004

A Simple Statistical Model for Analysis of QGP-droplet (Fireball) Formation

We construct the density of states for quarks and gluons using the `Thomas - Fermi model' for atoms and the `Bethe model' for nucleons as templates. With parameters to take care of the plasma (hydrodynamical) features of the QGP with a thermal potential for the interaction, we find a window in the parametric space of the model where observable QGP droplets of $ \sim $ 5 fm radius can occur with transition temperature in the range 140 MeV to 250 MeV. By matching with the expectations of Lattice Gauge estimates of the QGP-hadron transitions, we can further narrow the window, thereby restricting the allowed values of the flow-parameters of the model.

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arXiv2004

A Simple Statistical Model for QGP Phenomenology

We propose a simple statistical model for the density of states for quarks and gluons in a QGP droplet, making the Thomas-Fermi model of the atom and the Bethe-model for the nucleons as templates for constructing the density of states for the quarks and gluons with due modifications for the `hot' relativistic QGP state as against the `cold' non-relativistic atom and nucleons, which were the subject of the earlier `forebears' of the present proposal.We introduce `flow-parameters' $γ_{q,g}$ for the quarks and the gluons to take care of the hydrodynamical (plasma) flows in the QGP system as was done earlier by Peshier in his thermal potential for the QGP. By varying $γ_{g}$ about the `Peshier-Value' of $γ_{q} = 1/6$, we find that the model allows a window in the parametric space in the range $8γ_{q} \leq γ_{g} \leq 12γ_{q}$, with $γ_{q} =1/6$ (Peshier-Value), when stable QGP droplets of radii $\sim$ $6 fm$ appear at transition temperatures $100 MeV \leq T \leq 250 MeV$. The smooth cut at the phase boundary of the Free energy vs. droplet radius suggests a First - Order phase transition .On the whole the model offers a robust tool for studying QGP phenomenology as and when data from various ongoing experiments are available .

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