STAR abstracts submitted to APS02 Spring meeting

Overview talk

The Solenoidal Tracker At RHIC (STAR) is a large acceptance detector capable of tracking and identifying charged particles and measuring their momenta in the high multiplicity environment at RHIC. STAR simultaneously measures many experimental observables to study signatures of the predicted phase transition from hadronic matter to quark-gluon plasma. We will discuss how first results from \sqrt(s_{NN})=130 GeV Au+Au collisions already severely challenge and distinguish between competing models of the collisions, and whether a consistent picture of the collision dynamics is emerging. The status of the data analysis at 200 GeV will also be presented.

High-p_T PWG

The STAR collaboration at RHIC has measured charged hadrons up to pT=6 GeV/c in Au+Au collisions at sqrt(sNN)=130 GeV. We will present inclusive spectra and v2 at high pT, and discuss the implications for jet production in heavy ion collisions.

We present a measurement by the STAR Collaboration of the transverse energy distribution of Au+Au collisions at sqrt(sNN)=200 GeV. The hadronic fraction is obtained from the Time Projection Chamber (TPC) data and the electromagnetic fraction is obtained from the Barrel Electromagnetic Calorimeter (EMC) data. Energy deposition by charged hadrons is corrected on a track-wise basis, allowing an event-by-event measurement of the electromagnetic ET`. Energy deposition by neutral hadrons is estimated from Monte Carlo studies.

We will present ratios of identified particles at high momenta which were measured with the STAR-RICH at RHIC in Au-Au collisions. The RICH detector allows for the idenfication of pions and kaons with momenta up to 3 GeV/c and protons up to 5 GeV/c. The physics implications will be discussed.

Spectra PWG

We report on preliminary results from the STAR experiment on the proton and anti-proton transverse momentum (pT) and rapidity (y) distributions from Au+Au collisions at sqrt(sNN)=130 GeV taken during the first RHIC run in year 2000. Using the ionization energy loss (dE/dx) method, excellent particle identification up to a momentum of 1.0GeV/c is reached with the STAR Time Projection Chamber (TPC). This study will focus on the region pT<0.85 GeV/c, |y|<0.4. The experimental proton and anti-proton distributions will be studied as a function of collision centrality. The measured net-proton yield as a function of collision centrality will also be addressed. The physics discussion will focus on the baryon transport and collective expansion with comparison to predictions from transport models.

We report results of charged kaon production at mid-rapidity in Au+Au collisions at sqrt(sNN)=130 GeV measured by the STAR experiment at RHIC. The kaon tranverse mass distribution and the kaon production rate will be shown as a function of the collision centrality. Implications of the results will be discussed.

We will report the STAR preliminary results of mid-rapidity anti-proton/proton and charged kaon ratios from sqrt(sNN)=200GeV Au+Au collisions at RHIC. The results will be presented as a function of transverse momentum pt, rapidity y, and collision centrality. The systematic trends of the ratios as a function of the bombarding energy and the implication of collision dynamics will be discussed.

E-by-E PWG

Event anisotropy characterized by v2, often called elliptical flow, measures the momentum anisotropy in the transverse plane in non-central heavy ion collisions. In contrast to transverse radial flow from central collisions, elliptical flow is established at a relatively early stage of the collision. Therefore it is sensitive to the initial conditions and the possible onset of the hydrodynamics in the collision. In this paper, we will discuss the first results of elliptic flow for neutral particles, K0 and (, from minimum bias Au+Au collisions at sqrt(sNN) = 130 GeV. K0 and ( were reconstructed topologically in the STAR Time Project Chamber (TPC). The physics of the transverse momentum dependence of v2 of K0 and ( will be addressed compared to previously measured distributions from STAR for charged particles and the predictions of hydrodynamic and transport models.

Strangeness PWG

The STAR experiment at RHIC-BNL has the ability to reconstruct strange baryons with good acceptance. In this talk we present data on strangeness production in Au-Au collisions at $\sqrt{s_{NN}}$ = 130 and, depending on the progress of the analysis, preliminary data from the 200 GeV. More specifically we discuss Kaon and Lambda m$_T$ spectra and rapidity densities. The systematics of energy and centrality dependence will also be presented and discussed.

We will report preliminary results of mid-rapidity omega and anti-omega production from sqrt(sNN)=130GeV Au+Au collisions at RHIC measured by the STAR experiment. A comparison of the particles yields and ratios to thermal models will be discussed.