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 pT<3 GeV/c. We observed that the collective flow velocity starts from zero in p+p and peripheral Au+Au collisions and grows to 0.470±0.009c in central Au+Au collisions. The resulting (q-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 Au+Au collisions. The temperature and collective velocity are well described by a quadratic dependence on (q-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 Au+Au collisions.