Collective flow of pions in relativistic heavy-ion collisions

Abstract

3he transverse-momentum distributions of pions in the Au(1 GeV/nucleon) + Au collisions are analyzed. The calculations are carried out within relativistic mean-field one- and two-fluid models. The rapidity distributions of the mean transverse momentum of pions are found to be fairly sensitive to the nuclear equation of state and, especially, to the stopping power. It is shown that the collective flow of pions in the reaction plane always correlates with the “hot” flow of nucleons (i.e. those emitted from hot regions of nuclear system), while not always with the total nucleon flow. This “hot” nucleon flow can be experimentally singled out by selecting nucleons with sufficiently high transverse momenta. We predict that the “hot” nucleon flow selected in this way will always correlate with the pion flow. Available experimental data on transverse-momentum spectra of pions are compared with calculations employing various equations of state and stopping power.