Speakers
Description
Search for Quark-Gluon Plasma (QGP) and characterization of the matter formed at high temperature and energy density are the major goals of studying ultra-relativistic heavy-ion collisions at RHIC and the LHC. The bulk properties of QGP are governed by the light quarks and the heavy quarks are important probes of QGP as they are produced during initial hard scattering and they witness the entire plasma evolution. Due to the parton (quarks and gluons) energy loss in the medium, suppression in particle yields is observed in nucleus-nucleus collisions relative to pp collisions, where the formation of a medium is usually not expected. This medium modification is measured by the nuclear modification factor (RAA). In this contribution, the RAA is derived using the relaxation time approximation of the Boltzmann Transport Equation (BTE). The initial distribution is represented by thermodynamically consistent Tsallis distribution and the final distribution includes both the equilibrium and Tsallis distribution. The equilibrium distribution is represented by Boltzmann-Gibbs (BG) distribution and Boltzmann-Gibbs blastwave (BGBW) distribution separately. The experimental data from LHC are analyzed in this framework. It is shown that, the proposed approach explains the transverse momentum spectra and RAA of light as well as heavy flavored hadrons over wide range of transverse momenta at LHC. In addition, the mass ordering of the radial flow and relaxation time is shown.
In this formalism, we find that the final distribution function describes the transverse momentum spectra and the nuclear modification factor of pions, kaons, protons, $K^{*0}$ and $\phi$ upto considerably high $p_T$. The extracted radial flow seems to be mass dependent and favors a hydrodynamic behavior. $R_{AA}$ is found to be independent of the degree of non-extensivity, $q_{pp}$ after $p_T \sim$ 8 GeV/c. The flatness in $R_{AA}$, which is seen in higher-$p_T$, is observed to shift towards lower-$p_T$ for higher $q_{pp}$-values. The non-extenisvity parameter, $q_{pp}$ is mass dependent and it decreases for higher mass particles. Higher mass particles have a tendency of fast equilibration. The inclusion of radial flow, $\beta_r$ in the theory, favours the non-extensivity, as is expected intuitively.
| List of tracks | Fluctuation in initial conditions, collective flow and correlations |
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