P. Sahoo

Speed of sound in hadronic matter using non-extensive Tsallis statistics

Abstract.The speed of sound (

Electrical conductivity of Hot and Dense QCD matter at RHIC BES energies: A Color String Percolation Approach.

c_{s}

Energy and centrality dependent study of deconfinement phase transition in a color string percolation approach at RHIC energies

) is studied to understand the hydrodynamical evolution of the matter created in heavy-ion collisions. The quark-gluon plasma (QGP) formed in heavy-ion collisions evolves from an initial QGP to the hadronic phase via a possible mixed phase. Due to the system expansion in a first-order phase transition scenario, the speed of sound reduces to zero as the specific heat diverges. We study the speed of sound for systems which deviate from a thermalized Boltzmann distribution using non-extensive Tsallis statistics. In the present work, we calculate the speed of sound as a function of temperature for different q-values for a hadron resonance gas. We observe a similar mass cut-off behaviour in the non-extensive case for

Energy and centrality dependence of dNch/d

c^{2}_{s}

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by including heavier particles, as is observed in the case of a hadron resonance gas following equilibrium statistics. Also, we explicitly show that the temperature where the mass cut-off starts varies with the q-parameter which hints at a relation between the degree of non-equilibrium and the limiting temperature of the system. It is shown that for values of q above approximately 1.13 all criticality disappears in the speed of sound, i.e. the decrease in the value of the speed of sound, observed at lower values of q, disappears completely.

and dET/d

Recently, transport coefficients, viz., shear viscosity, electrical conductivity, etc., of strongly interacting matter produced in heavy-ion collisions have drawn considerable interest. We study the normalized electrical conductivity (σel/T) of hot QCD matter as a function of temperature (T) using the color string percolation model (CSPM). We also study the temperature dependence of shear viscosity and its ratio with electrical conductivity for the QCD matter. We compare CSPM estimations with various existing results and lattice QCD predictions with (2+1) dynamical flavors. We find that σel/T in CSPM has a very weak dependence on the temperature. We compare CSPM results with those obtained in the Boltzmann approach to multiparton scatterings model. A good agreement is found between CSPM results and predictions of the Boltzmann approach to multiparton scatterings with a fixed strong coupling constant.

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Abstract.We take the experimental data for transverse momentum spectra of identified charged hadrons in different centrality classes for nucleus-nucleus

in heavy-ion collisions from

(A+A)

\sqrt{s_{NN}} = 7.7

(A+A) collisions at various Relativistic Heavy-Ion Collider (RHIC) energies measured by the STAR Collaboration. We analyse these data in the framework of the color string percolation model (CSPM) in order to extract various percolation parameters at different centralities at RHIC energies to study the effect of collision geometry and collision energy. We use these parameters to study the centrality dependent behaviour of initial temperature of the percolation cluster, energy density, average transverse momentum, shear viscosity to entropy density ratio (

GeV to 5.02 TeV

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