Center for Astroparticle Physics and Space Science

Salt Lake, India

Center for Astroparticle Physics and Space Science

Salt Lake, India
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Bhattacharyya A.,University of Calcutta | Ghosh S.K.,Bose Institute of India | Ghosh S.K.,Center for Astroparticle Physics and Space Science | Ray R.,Bose Institute of India | And 5 more authors.
EPL | Year: 2016

We discuss the 2+1 flavor Polyakov loop enhanced Nambu-Jona-Lasinio model in a finite volume. The main objective is to check the volume scaling of thermodynamic observables for various temperatures and chemical potentials. We observe the possible violation of the scaling with system size in a considerable window along the whole transition region in the T-μq plane.


Saha K.,Center for Astroparticle Physics and Space Science | Saha K.,Bose Institute of India | Upadhaya S.,Center for Astroparticle Physics and Space Science | Upadhaya S.,Bose Institute of India | Ghosh S.,University of Calcutta
Modern Physics Letters A | Year: 2017

We have gone through a comparative study on two different kinds of bulk viscosity expressions by using a common dynamical model. The Polyakov-Nambu-Jona-Lasinio (PNJL) model in the realm of mean-field approximation, including up to eight quark interactions for 2+1 flavor quark matter, is treated for this common dynamics. We have probed the numerical equivalence as well as discrepancy of two different expressions for bulk viscosity at vanishing quark chemical potential. Our estimation of bulk viscosity to entropy density ratio follows a decreasing trend with temperature, which is observed in most of the earlier investigations. We have also extended our estimation for finite values of quark chemical potential. © 2016 World Scientific Publishing Company.


Ray D.,Bose Institute of India | Chatterjee A.,Bose Institute of India | Majumdar D.,Indian National Environmental Engineering Research Institute | Ghosh S.K.,Bose Institute of India | And 3 more authors.
Atmospheric Research | Year: 2017

The temporal variations and major sources of polycyclic aromatic hydrocarbons (PAH) intrinsic to PM10 were investigated over a tropical urban atmosphere on the Indo-Gangetic Plain (IGP) and for the first time over a high altitude urban atmosphere at eastern Himalaya in India. Samples were collected over Kolkata, a megacity and Darjeeling, a high altitude (2200 m asl) hill station in eastern India during the dry season (October 2015–May 2016). Fourteen PAHs were detected and quantified over Kolkata and Darjeeling during three consecutive seasons, viz., post-monsoon, winter and pre-monsoon. The total-PAHs concentrations were in the order of winter (78.08–146.71 ngm− 3) > post-monsoon (83.42–113.52 ngm− 3) > pre-monsoon (37.65–109.27 ngm− 3) at Kolkata, whereas post-monsoon (22.72–36.60 ngm− 3) > winter (8.52–28.43 ngm− 3) > pre-monsoon (5.45–13.34 ngm− 3) at Darjeeling. The observed seasonality of PAHs at Kolkata vis-a-vis Darjeeling has been explored in the light of anthropogenic activities, boundary layer dynamics and meteorological parameters such as temperature, relative humidity, wind speed and solar radiation. Negative correlation was observed between total-PAHs and temperature, wind speed and solar radiation over Kolkata and Darjeeling. The positive matrix factorization (PMF) model calculations suggested that coal (26%), petrol (24%) and diesel (17%) combustion, commercial and household kitchens (18%) and municipal solid waste incineration (15%) are the possible contributors to the PM10 associated PAHs over Kolkata whereas diesel (37%), commercial and household kitchens (23%), coal (21%) and petrol (20%) are the possible PM10 associated PAH sources over Darjeeling. © 2017 Elsevier B.V.


Bhattacharyya A.,University of Calcutta | Bhattacharyya A.,Center for Astroparticle Physics and Space Science | Bhattacharyya A.,Bose Institute of India | Ghosh S.K.,University of Calcutta | And 17 more authors.
Physical Review D | Year: 2017

The Polyakov-Nambu-Jona-Lasinio model has been quite successful in describing various qualitative features of observables for strongly interacting matter, that are measurable in heavy-ion collision experiments. The question still remains on the quantitative uncertainties in the model results. Such an estimation is possible only by contrasting these results with those obtained from first principles using the lattice QCD framework. Recently a variety of lattice QCD data were reported in the realistic continuum limit. Here we make a first attempt at reparametrizing the model so as to reproduce these lattice data. We find excellent quantitative agreement for the equation of state. Certain discrepancies in the charge and strangeness susceptibilities as well as baryon-charge correlation still remain. We discuss their causes and outline possible directions to remove them. © 2017 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.


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.


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.


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.

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