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Bhattacharyya A.,University of Calcutta | Ghosh S.K.,Center for Astroparticle Physics and Space Science | Ghosh S.K.,Bose Institute of India | Majumder S.,Center for Astroparticle Physics and Space Science | And 3 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We report the first case study of the phase diagram of 2+1 flavor strongly interacting matter in β equilibrium, using the Polyakov-Nambu-Jona-Lasinio model. Physical characteristics of relevant thermodynamic observables have been discussed. A comparative analysis with the corresponding observables in the Nambu-Jona-Lasinio model is presented. We find distinct differences between the models in terms of a number of thermodynamic quantities like the speed of sound, specific heat, various number densities, as well as entropy. The present study is expected to give us a better insight into the role that the superdense matter created in heavy-ion collision experiments plays in our understanding of the properties of matter inside the core of supermassive stars in the Universe. © 2012 American Physical Society.


Alam J.-E.,Variable Energy Cyclotron Center | Mohanty B.,Variable Energy Cyclotron Center | Majumder S.,Center for Astroparticle Physics and Space Science | Majumder S.,Bose Institute of India | And 4 more authors.
Nuclear Physics A | Year: 2012

We present a study of τ +τ - lepton pair production in Pb+Pb collisions at sNN=5.5 TeV. The larger τ ± mass (~1.77 GeV) compared to e ± and μ ± leads to considerably small hadronic contribution to the τ +τ - pair invariant mass (M) distribution relative to the production from thermal partonic sources. The quark-anti-quark annihilation processes via intermediary virtual photon, Z and Higgs bosons have been considered for the production of τ +τ -. We observe that the contribution from Drell-Yan process dominates over thermal yield for τ +τ - pair mass from 4 to 20 GeV at the LHC energy. We also present the ratio of τ lepton pair yields for nucleus-nucleus collisions relative to yields from p+p collisions scaled by number of binary collisions at LHC energies as a function τ pair mass. The ratio is found to be significantly above unity for the mass range 4 to 6 GeV. This indicates the possibility of detecting τ +τ - pair from quark-gluon plasma (QGP) in the mass window 4≤M(GeV)≤6. © 2012 Elsevier B.V.


Bhattacharyya A.,University of Calcutta | Das S.,Center for Astroparticle Physics and Space Science | Das S.,Bose Institute of India | Ghosh S.K.,Center for Astroparticle Physics and Space Science | And 5 more authors.
Proceedings of the Indian National Science Academy | Year: 2015

We present temperature (T) dependence of higher order fluctuations of conserved baryon number in Excluded Volume Hadron Resonance Gas (EVHRG) model. Products of moments, such as ratio of variance to mean (σ2=M), product of skewness and standard deviation (Sσ), product of kurtosis and variance (κσ2), for net-proton has been evaluated on the phenomenologically determined freeze-out curve and has been compared with the experimental data measured by STAR experiment. © Printed in India.


Ghosh S.K.,Center for Astroparticle Physics and Space Science | Ghosh S.K.,Bose Institute of India | Raha S.,Center for Astroparticle Physics and Space Science | Raha S.,Bose Institute of India | And 6 more authors.
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We present a detailed study of the variation of shear viscosity η, with temperature and baryon chemical potential within the framework of the Polyakov-Nambu-Jona-Lasinio model. η is found to depend strongly on the spectral width of the quasiparticles present in the model. The variation of η across the phase diagram has distinctive features for different kinds of transitions. These variations have been used to study the possible location of the critical end point and are cross-checked with similar studies of variations of specific heat. Finally, using a parametrization of the freeze-out surface in heavy-ion collision experiments, the variation of the shear viscosity to entropy density ratio has also been discussed as a function of the center-of-mass energy of collisions. © 2015 American Physical Society.

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