Resonance production in RHIC collisions

Abstract

Short lived resonances are sensitive to the properties of the medium produced in heavy ion collision, in particular the temperature, density and expansion velocity. Thermal models underpredict the yield of K(892) and Λ(1520) in Au+Au collisions which allows us to conclude that an extended hadronic interaction phase exists between chemical and thermal freeze-out. During this time the decay particles of resonances will re-scatter and coalesce to regenerate resonances. These mechanisms affect the resonance yield mostly in the low momentum region below 1 GeV/c. Therefore the nuclear suppression factor RAA of resonances with more re-scattering than regeneration will be suppressed compared to stable particles in that pT range. It is interesting to study the RAA of resonances at higher momenta where the spectra of non-resonant particles exhibit effects such as enhancement through constituent quark recombination and quenching in the dense partonic medium. In addition the RAA’s of strange particles show the effect of canonical suppression on the nuclear suppression factor which leads to a significant difference between RAA and RCP, in particular for strange baryons. Therefore the RAA and the elliptic flow v2 for strange resonances in comparison to strange particles are investigated.