Transverse pressure and strangeness dynamics in relativistic heavy-ion reactions

Abstract

Transverse hadron spectra from proton–proton, proton–nucleus and nucleus–nucleus collisions from 2 A GeV to 21.3 A TeV are investigated within two independent transport approaches (HSD and UrQMD). For central Au+Au (Pb+Pb) collisions at energies above Elab ∼ 5 A GeV, the measured K± transverse mass spectra have a larger inverse slope parameter than expected from the default calculations. The additional pressure—as suggested by lattice QCD calculations at finite quark chemical potential μq and temperature T—might be generated by strong interactions in the early pre-hadronic/partonic phase of central Au+Au (Pb+Pb) collisions. This is supported by a non-monotonic energy dependence of v2/⟨pT⟩ in the present transport model.