A Non-extensive Equilibrium analysis of $π^{+}$ $p_{T}$ Spectra at RHIC

Abstract

By analyzing the dynamical properties of particle production in relativistic heavy ion collisions, it is possible to characterize the final stage of the equilibration process occurring in the collision fireball. In this work, we use the Hagedorn model coupled with non-extensive statistics to evaluate the transverse momentum spectra of positive pions for various event centrality classes in Au+Au collisions at RHIC with center-of-mass energies of 62.4GeV/A and 200GeV/A. We find that, by assuming an energy distribution that incorporates particle correlations, it is possible to explain the entire $π^{+}$ $p_{T}$ spectrum as measured by RHIC. We find that spectra from central collisions, when compared to peripheral collisions, are consistent with a system that has smaller values of the non-extensivity parameter "q" and higher values of temperature. Comparison between different beam energies also shows a variation of the "q" parameter. The result is discussed using the interpretation that the "q" parameter is a measure of particle correlations within the system. Under this assumption, our results show that more central collisions are consistent with a system with less particle correlations.