K0s and \Lambda\ production in Pb--Pb collisions with the ALICE experiment

We present the study of K0s and Lambda production performed with the ALICE experiment at the LHC in Pb--Pb collisions at \sqrt{s_NN}=2.76 TeV and pp collisions at \sqrt{s}=0.9 and 7 TeV. The K0s and Lambda particles are reconstructed via their V0 decay topology allowing their identification up to high transverse momenta. The corresponding baryon/meson ratios as a function of transverse momentum are extracted for Pb--Pb collisions in centrality bins and in the transverse momentum range from 1 to 6 GeV/c. They are also compared with those measured in pp events at the LHC energies of 0.9 and 7 TeV as well as in Au--Au collisions at \sqrt{s_NN} = 62.4 and 200 GeV from RHIC.Comment: 4 pages, 4 figures, proceedings of Quark Matter 2011 (May 23rd-28th 2011, Annecy, France

Recent high pT measurements in STAR

After five years of data taking, the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory provides precise measurements of particle production at high transverse momentum in p-p, d-Au, and Au-Au collisions at sqrt(s) = 200 GeV. We review recent results on the flavor dependence of high pT particle suppression and hadron particle spectra at sqrt(s) = 62.4 GeV. New results on two-particle angular correlations for identified trigger particles and for low momentum associated charged hadrons in p-p and Au-Au as well as near-side $\Delta\eta$ correlations will be presented and discussed.Comment: 5th International Conference on Physics and Astrophysics of Quark Gluon Plasma, Calcutta. 8 pages, 10 figures, submitted to J. Phys. G: Nucl. Part. Phy

Event-by-Event Fluctuations at 40, 80, and 158 AGeV/c in Pb+Au Collisions

Event-by-event fluctuations of mean pt and net charge in 40, 80, and 158 AGeV/c Pb+Au collisions are presented. The observed dynamical mean pt fluctuations in central events of about 1 % are very similar to results from RHIC. The centrality dependence of mean pt fluctuations at 158 AGeV/c shows a peculiar non-monotonic pattern with respect to the extrapolation from the fluctuations measured in p+p collisions. Dynamical net charge fluctuations smaller than the charge conservation limit are observed. After correction for charge conservation, the measured fluctuation signal in central events is comparable to RHIC results.Comment: 4 pages, 6 figures, proceedings of the Quark Matter 2004, in Oakland, USA, to be published in Journal of Physics G: Nuclear and Particle Physic

Traces of Thermalization at RHIC

I argue that measurements of Au+Au collisions at 20, 130 and 200 GeV of the centrality dependence of the mean p_t together with p_t and net-charge fluctuations reflect the approach to local thermal equilibrium.Comment: 4 pages, 4 eps figures, for proc. Quark Matter 2004, to be published in J. Phys.

Global polarization measurement in Au+Au collisions

The system created in non central relativistic nucleus-nucleus collisions carries large angular orbital momentum. Due to spin-orbital coupling, produced particles could be globally polarized along the direction of the system angular momentum. We present results of a measurement of Lambda hyperon global polarization in Au+Au collisions at the center of mass energies 62 and 200 GeV with the STAR detector at RHIC. The observed global polarization of Lambda hyperons in the STAR acceptance is consistent with zero within the precision of the measurement. The obtained upper limit, |P_Lambda| < 0.01, is significantly below the theoretical values discussed recently in the literature.Comment: Talk given at SQM 2006, International Conference on Strangeness in Quark Matter, March 26-31, 2006, Los Angeles CA; 4 pages, 2 figure

An Overview of Fluctuation and Correlation Results in Relativistic Heavy Ion Collisions

A great deal of recent data on event-by-event fluctuation and correlation measurements has been released by several experiments at the SPS and RHIC. Recent results on charge fluctuations, balance functions in pseudorapidity, and average transverse momentum fluctuations will be reviewed. The results will be compared to various model predictions after examining contributions to each observable from known physics processes.Comment: 8 pages, 3 figures. Contribution to the Proceedings of the 17th International Conference on Ultra Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004), Oakland, California, 11-17 Jan 2004. Submitted to J.Phys.

π/K/p\pi/K/p production and Cronin effect from p+p, d+Au and Au+Au collisions at sNN=200\sqrt{s_{NN}}= 200 GeV from the PHENIX experiment

We present results on identified particle production in p+p, d+Au and Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV at mid-rapidity measured by the PHENIX experiment. The centrality and flavor dependence of the Cronin effect in d+Au collisions is measured. The Cronin effect for the protons in d+Au is larger than that for the pions, but not large enough to account for the ``anomalous'' proton to pion ratio in central Au+Au collisions.Comment: 5 pages, 3 figures, contribution to the proceedings of the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004

Overview of Hard processes at RHIC: high-pt light hadron and charm production

An overview of the experimental results on high-pt light hadron production and open charm production is presented. Data on particle production in elementary collisions are compared to next-to-leading order perturbative QCD calculations. Particle production in Au+Au collisions is then compared to this baseline.Comment: 9 pages, 6 figures, Strange Quark Matter 200

Open Charm Production at STAR

We present the open charm spectra at mid-rapidity from direct reconstruction of D0, D* and D+/- in d+Au collisions at sqrt(sNN)=200 GeV using the STAR detector at RHIC. The indirect electron/positron measurements via charm semileptonic decays in p+p and d+Au collisions are also reported. The total c\bar(c) cross section per nucleon-nucleon collision is extracted from both direct and indirect measurements and are consistent with each other. By combining the D0 and semileptonic measurements together, the cross section of 1.4+/-0.2+/-0.4 mb is higher than expectations from PYTHIA and other pQCD calculations. The open charm pT distribution from direct measurements covers the pT range up to ~10 GeV/c and follows a power-law distribution.Comment: 7 pages, 4 figures, proceedings for Hot Quark 04 Conference. submitted to J. Phys. G: Nucl. Phy

Recent Results on Strangeness Production at RHIC

Due to its large acceptance, the STAR experiment has acquired a wealth of data on strangeness production for a variety of collisions systems and energies, from p+p to Au+Au. By using the yields and spectra, we address the evolution of the bulk system, including strangeness enhancement and the flavour dependence of radial and elliptic flow. Utilising the fact that we can identify strange baryons and mesons, we investigate different hadronization mechanisms in the intermediate and high p$_{T}$ regions. The ratios of the particle yields, measured to high p$_{T}$, are used to further investigate the range and applicability of the previously reported anomalous baryon production. We also study two-particle azimuthal correlations of identified particles in order to investigate any flavour dependence of jet fragmentation in the available p$_{T}$ range. Data was presented for a number of different collision systems and energies.Comment: Proceedings of SQM'06 Conference, LA, 2006 (submitted to J. Phys. G