A. R. Timmins

The centrality dependence of strange baryon and meson production at RHIC

We report Cu+Cu √SNN = 200 GeV strange baryon and meson yields which reveal that collision geometry plays a crucial role for particle production. Relative to Au+Au collisions with similar numbers of participating nucleons, (N part ), at the same energy, central Cu+Cu collisions exhibit higher mid-rapidity integrated yields per (N part ) for the A, A, K 0 S particles. In addition, higher mid- p T A /K 0 S ratios are observed in Cu+Cu for the overlapping (N part ) range.

Scaling Properties of Hyperon Production in Au+Au Collisions at {radical}(s{sub NN})=200 GeV

We present the scaling properties of Lambda, Xi, and Omega in midrapidity Au+Au collisions at the Brookhaven National Laboratory Relativistic Heavy Ion Collider at sqrt[s_{NN}]=200 GeV. The yield of multistrange baryons per participant nucleon increases from peripheral to central collisions more rapidly than that of Lambda, indicating an increase of the strange-quark density of the matter produced. The strange phase-space occupancy factor gamma_{s} approaches unity for the most central collisions. Moreover, the nuclear modification factors of p, Lambda, and Xi are consistent with each other for 2<p_{T}<5 GeV/c in agreement with a scenario of hadron formation from constituent quark degrees of freedom.

{delta}{phi}{delta}{eta} correlations in central Au+Au collisions at {radical}(s{sub NN})=200 GeV

We report charged particle pair correlation analyses in the space of Δϕ (azimuth) and Δη (pseudorapidity), for central Au+Au collisions at √sNN=200 GeV in the STAR detector. The analysis involves unlike-sign charged pairs and like-sign charged pairs, which are transformed into charge-dependent (CD) signals and charge-independent (CI) signals. We present detailed parametrizations of the data. A model featuring dense gluonic hot spots as first proposed by Van Hove predicts that the observables under investigation would have sensitivity to such a substructure should it occur, and the model also motivates selection of transverse momenta in the range 0.8

THE CENTRALITY DEPENDENCE OF STRANGE BARYON AND MESON PRODUCTION IN CU+CU AND AU+AU FOR

Transverse momentum spectra of Λ and particles are presented for Cu+Cu at collisions observed at STAR, and compared to Au+Au measurements at the same energy. For both systems, a number of observables are shown to increase at mid-rapidity (|y| < 0.5) with increasing centrality. These are the integrated Λ and yields, the integrated ? and yields per participating nucleon, and mid-pT(1 GeV/c → 4.5 GeV/c) ratios. The RCP ratio is found to be higher for the Λ yields at mid-pT compared to the yields for both the Cu+Cu and Au+Au data. In contrast, when similar numbers of participating nucleons are considered for the Cu+Cu and Au+Au data, an indication of increased bulk strangeness production and a higher mid-pT(1 GeV/c → 4.5 GeV/c) ratio are found, for Cu+Cu.

\sqrt{^SNN} = 200 {\rm GEV}

We present the directed flow (v(1)) measured in Au+Au collisions at root s(NN)=62.4 GeV in the midpseudorapidity region parallel to eta parallel to < 1.3 and in the forward pseudorapidity region 2.5 <parallel to eta parallel to < 4.0. The results are obtained using the three-particle cumulant method, the event plane method with mixed harmonics, and for the first time at the Relativistic Heavy Ion Collider, the standard method with the event plane reconstructed from spectator neutrons. Results from all three methods are in good agreement. Over the pseudorapidity range studied, charged particle directed flow is in the direction opposite to that of fragmentation neutrons.