Suppression of high transverse momentum hadrons at RHIC by (pre–) hadronic final state interactions

We investigate transverse hadron spectra from proton+proton, deuteron+Au and Au+Au collisions at √ s = 200GeV and √ s = 17.3GeV within the Hadron–String– Dynamics (HSD) approach which is based on quark, diquark, string and hadronic degrees of freedom as well as Pythia calculations for the high p⊥ spectra. The comparison to experimental data on transverse mass spectra from p+p, d+Au and Au+Au reactions shows that pre–hadronic effects are responsible for both the hardening of the spectra for low transverse momenta (Cronin effect) as well as the suppression of high p⊥ hadrons. The interactions of formed hadrons are found to be negligible in central Au+Au collisions at √ s = 200GeV for p⊥ ≥ 6GeV/c, but have some importance for the shape of the ratio RAA at lower p⊥ values (≤ 6GeV/c). The large suppression seen experimentally is attributed to the inelastic interactions of ’leading’ pre-hadrons with the dense environment, which could be partly of colored partonic nature in order to explain the large attenuation seen in most central Au+Au collisions.