Spectra and radial flow in relativistic heavy ion collisions with Tsallis statistics in a blast-wave description

We have implemented the Tsallis statistics in a Blast-Wave model (TBW) and applied it to midrapidity transverse-momentum spectra of identified particles measured at BNL Relativistic Heavy Ion Collider (RHIC). This new TBW function fits the RHIC data very well for ${p}_{T}<3$ GeV/$c$. We observed that the collective flow velocity starts from zero in $p+p$ and peripheral $\mathrm{Au}+\mathrm{Au}$ collisions and grows to $0.470\ifmmode\pm\else\textpm\fi{}0.009c$ in central $\mathrm{Au}+\mathrm{Au}$ collisions. The resulting $(q\ensuremath{-}1)$ parameter, which characterizes the degree of nonequilibrium in a system, indicates an evolution from a highly nonequilibrated system in $p+p$ collisions toward an almost thermalized system in central $\mathrm{Au}+\mathrm{Au}$ collisions. The temperature and collective velocity are well described by a quadratic dependence on $(q\ensuremath{-}1)$. Two sets of parameters in our TBW are required to describe the meson and baryon groups separately in $p+p$ collisions while one set appears to fit all spectra in central $\mathrm{Au}+\mathrm{Au}$ collisions.

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