Soft and Hard Interactions in proton + proton collisions at sqrt(s)=200GeV

Abstract

We present a detailed study of particle production at mid-rapidity in proton + proton collisions at RHIC for sqrt(s)=200GeV. The transverse momentum spectra and the <pT> of inclusive hadrons and identified particles as a function of multiplicity are measured in minimum bias, "soft" and "hard" event classes. It is found that the multiplicity dependence of <pT> in soft events in proton + proton collisions does not change from RHIC to Tevetron while there is no such scaling behavior in minimum-bias and hard events. The baryon and strangeness production derived from the particle ratios of K-/pi- and Pbar/pi- are measured to be different in "soft" and "hard" events. These results are compared to model predictions and those from Au+Au collisions at RHIC.