Proton and pion transverse spectra at RHIC from radial flow and finite size effects

摘要

We show that the proton and pion transverse momentum distributions measuredat RHIC for all collision centralities for pions and most of the collisioncentralities for protons, can be simultaneously described in terms of a thermalmodel with common values for the radial flow and temperature, when accountingfor the finite size of the interaction region at the time of decoupling. Weshow that this description is obtained in terms of a simple scaling law of thesize of the interaction region with the number of participants in thecollision. The behavior of the proton to pion ratio at mid-rapidity can also beunderstood as a consequence of the strength of the radial flow and system sizereached at RHIC energies.