Bose-stimulated pion production in relativistic nuclear collisions

We demonstrate the importance of the Bose-statistical effects for pion production in relativistic heavy-ion collisions. The evolution of the pion phase-space density in central collisions of ultrarelativistic nuclei is studied in a simple kinetic model taking into account the effect of Bose-stimulated pion production by the NN collisions in a dense cloud of mesons. It is assumed that pions are produced within a finite formation time at the stage of the projectile-target interpenetration. The mutual slowing down of nuclei is described schematically by introducing an effective deceleration length. The role of the quasideuteron and Δ-isobar mechanisms of pion absorption is investigated. The model predicts the enhancement of the soft pion yield as compared to inclusive pp data. The effect is sensitive to the pion formation time and is more pronounced at midrapidity and for heavy nuclei. The results are compared with pion spectra observed in central 10.7A GeV Au+Au and 200A GeV S+S collisions. We suggest new experiments sensitive to the Bose enhancement phenomena