Investigation of the high-pT strange baryon anomalies at RHIC

Abstract

Results from RHIC have shown that there is an enhanced baryon/meson ratio in the intermediate transverse momentum range (2<pT<6 GeV/c) in Au+Au collisions at both \(\sqrt{s_{NN}}\) =130 and 200 GeV. This was initially demonstrated by measurements of the p/π- ratio which was then extended in pT by the Λ/K0S ratio. The data were successfully described by models utilising different hadronization mechanisms: those having recombination of quarks and others having an interplay between flow, jet quenching and incorporating baryon junction loops. The strange particle data from the first Au+Au run at \(\sqrt{s_{NN}}\) =200 GeV gave tantalising hints that the observed enhancement of baryons compared to mesons was diminished by a pT of 6 GeV/c, but a lack of statistics in this range made a definitive statement impossible. Here we present an extended analysis of identified strange baryons and mesons in Au+Au collisions at \(\sqrt{s_{NN}}\) =200 GeV using data obtained by the STAR experiment from the 2004 running period. The increase in statistics extends the measurement of Λ hyperons out to at least 7 GeV/c and K0S mesons out to 9 GeV/c. This data allows us to place limits on the range where in-vacuum fragmentation functions are applicable and the effect of baryon dominance is reduced. We also discuss the prospects for making these measurements using multiply-strange baryons and mesons (Ω and ϕ).