Betty Abelev

A hot and dense medium is produced in central Au¹⁹⁷+Au ¹⁹⁷ collisions at [special characters omitted]_NN = 200 GeV at the Relativistic Heavy Ion Collider (RHIC) in Brookhaven National Laboratory. A particular puzzle has been the origin of hadrons produced in the inter-mediate transverse momentum (2 < p_T < 6 GeV/c) region. Recombination and Coalescence models have been proposed to explain the mechanism of particle production in this energy range. Because the production of s-quarks via parton fragmentation is suppressed in the p_T region of interest with respect to the lighter quarks, the fragmentation contribution of s-quarks to strange particles should also be suppressed. Therefore, particles made entirely of s and s¯ quarks which originated from fragmentation are not expected to be detected. A statistical measurement of jets via azimuthal correlations using multi-strange (Ξ^± and Ω^±) baryons as trigger particles is performed in the most central Au+Au collisions. Contrary to predictions, a strong same-side peak (correlated with the jet direction) with non-zero yield has been observed in both cases. The correlation function for Ξ baryons is also studied as a function of pseudorapidity η and azimuthal angle &phis;. An elongation in Δη, commonly called the “ridge”, is observed under the trigger-particle (same-side) peak.

The Ξ^± correlation function with charged particles has been obtained in p+p and d+Au minimum bias collisions for comparison with that in central Au+Au events. While there are insufficient statistics to calculate the same-side yields in the p+p data, the yield in the d+Au data is extracted. Correlation functions are also studied in events triggered on high-energy deposits in the electromagnetic calorimeter. These will be presented along with the possibility of using the STAR calorimeter as an anti-baryon trigger.