Thermodynamic parameters at kinetic freeze-out in relativistic heavy-ion collisions using Tsallis statistics

Thermodynamic properties of the hot and dense system produced in relativistic heavy-ion collisions have been studied by analyzing the transverse momentum ($p_{\rm T}$) spectra of emitted particles (pions, kaons, and protons). The spectra are fitted using the non-extensive Tsallis statistics. The fit parameters, $q$ and $T$, provide the degree of deviation of the system from an equilibrium state and the effective temperature at freeze-out, respectively. These parameters are presented as a function of collision energy, collision centrality, and different fit ranges in $p_{\rm T}$ for available experimental data at Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) energies. An anti-correlation between the two fit parameters has been observed. With the increase of the collision energy, $q$ increases in a systematic manner whereas $T$ has a decreasing trend. For central collisions, $q$ and $T$ have a strong dependence on the fitting ranges of $p_{\rm T}$, however, for peripheral collisions there is a minor dependency on $p_{\rm T}$. The Tsallis parameters are found to have mass ordering, which needs further investigation with the inclusion of radial flow.