Thermodynamic properties at the kinetic freeze-out in the Au plus Au and Cu plus Cu collisions at the RHIC using the Tsallis distribution

摘要

The thermodynamic properties of charged particles, such as the energy density, pressure, entropy density, particle density, and squared speed of sound at the kinetic freeze-out in the Au + Au collisions from the relativistic heavy ion collider (RHIC) beam energy scan program (root s(NN) = 7.7-200 GeV) and in the Cu + Cu collisions at root s(NN) = 62.4, 200 GeV are studied using the thermodynamically consistent Tsallis distribution. The energy density, pressure, and particle density decrease monotonically with the collision energy for the same collision centrality; These properties also decrease monotonically from the central to peripheral collisions at the same collision energy. While the scaled energy density epsilon/T-4 and scaled entropy density s/T-3 demonstrate the opposite trend with the collision energy for the same collision centrality. There is a correlation between epsilon/T-4 and s/T-3 at the same centrality. In addition, the squared speed of sound was calculated to determine that all the collision energies share nearly the same value at different collision centralities.

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