v4 for identified particles at RHIC from viscous hydrodynamics

Using ideal and viscous hydrodynamics, the ratio of azimuthal moments v4/(v2)^2 is calculated for pions, protons, and kaons in sqrt{s}=200 A*GeV Au+Au collisions. For any value of viscosity here is little dependence on particle species. Ideal hydrodynamics and data show a flat curve as a function of pt. Adding viscosity in the standard way destroys this flatness. However, it can be restored by replacing the standard quadratic ansatz for delta f (the viscous correction to the distribution function at freeze-out) with a weaker momentum dependence.Comment: Proceedings of Hot Quarks 2010, 21-26 June 2010 La Londe Les Maures, 4 pages, 2 figure

Event anisotropy of identified π0\pi^{0}, photon and electron compared to charged π\pi, KK, pp and deuteron in sNN\sqrt{s_{NN}} = 200 GeV Au+Au at PHENIX

We report the recent results of event anisotropy analysis focused on $v_2$ in $\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions at PHENIX.Comment: 4 pages, 3 figures, contribution to the proceedings of the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter, Oakland, January 11-17, 2004). To appear in the proceedings (Journal of Physics G

Excitation functions of baryon anomaly and freeze-out properties at RHIC-PHENIX

The intermediate $p_T$ region (2 - 5 GeV/$c$) in central Au+Au collisions at RHIC has a rich physics content. The (anti)proton to pion ratio at the intermediate $p_T$ gives us a powerful tool to investigate the bulk properties of the hot and dense matter created at RHIC and their hadronization processes. We present the preliminary results of identified charged hadron spectra at the lower beam energies at RHIC. The excitation function of (anti)proton to pion ratios from SPS to RHIC are shown. We also discuss the onset of the baryon enhancement at the high energy heavy ion collisions.Comment: 4 pages, 3 figures, Quark Matter 2006 conference proceeding

PHENIX Studies of the Scaling Properties of Elliptic Flow at RHIC

Recent PHENIX elliptic flow ($v_2$) measurements for identified particles produced in Au+Au and Cu+Cu collisions at $\sqrt{s_{NN}}=200$ GeV are presented and compared to other RHIC measurements. They indicate universal scaling of $v_2$ compatible with partonic collectivity leading to the flow of light, strange and heavy quarks with a common expansion velocity field.Comment: Proceedings, Quark Matter 2006, Shanghai, Chin

Recent PHENIX Results on Open Heavy Flavor

Throughout the history of the RHIC physics program, questions concerning the dynamics of heavy quarks have generated much experimental and theoretical investigation. A major focus of the PHENIX experiment is the measurement of these quarks through their semi-leptonic decay channels at mid and forward rapidity. Heavy quark measurements in $p+p$ collisions give information on the production of heavy flavor, without complications from medium effects. New measurements in $d+$Au and Cu+Cu indicate surprising cold nuclear matter effects on these quarks at midrapidity, and provide a new baseline for interpretation of the observed suppression in Au+Au collisions. When considered all together, these measurements present a detailed study of nuclear matter across a wide range of system size and temperature. Here we present preliminary PHENIX measurements of non-photonic electron spectra and their centrality dependence in $d$+Au and Cu+Cu, and discuss their implications on the current understanding of parton energy loss in the nuclear medium.Comment: 4 pages, 3 figures, to appear in the proceedings of Quark Matter 201

Characteristics of Parton Energy Loss Studied with High-p_T Particle Spectra from PHENIX

In the first three years of the physics program at the Relativistic Heavy Ion Collider (RHIC) a picture was established in which the suppression of hadrons at high transverse momenta (p_T) in central Au+Au collisions is explained by energy loss of quark and gluon jets in a medium of high color-charge density. Measurements of single particle spectra for a smaller nucleus (Cu), for different center-of-mass energies and with higher statistics were performed in the subsequent years and are used to test predictions and assumptions of jet quenching models in more detail. The measurements presented here are consistent with a parton energy loss scenario so that these models can be used to relate the observed suppression to properties of the created medium.Comment: To appear in the proceedings of 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008), Jaipur, India, 04-10 Feb 200

Hadron Production at Intermediate pTp_T at RHIC

Large proton and antiproton enhancement with respect to pions has been observed at intermediate transverse momentum $p_T \approx$ 2-5 GeV/$c$ in Au+Au collisions at RHIC. To investigate the possible source of this anomaly, the production of $\phi$ mesons and two particle angular correlations triggered by mid-$p_T$ baryons or mesons are studied. We also present the first measurement of proton and antiproton production at $\sqrt{s_{NN}} = 62.4$ GeV in Au+Au collisions, which aims to study the energy dependence of the observed baryon enhancement.Comment: 7 pages, 5 figures, proceedings of Hot Quarks 2004 workshop, Taos Valley, New Mexico, 18-24 Jul 2004,, to be published in J. Phys.

Quarkonium production in ultra-relativistic nuclear collisions: suppression vs. enhancement

After a brief review of the various scenarios for quarkonium production in ultra-relativistic nucleus-nucleus collisions we focus on the ingredients and assumptions underlying the statistical hadronization model. We then confront model predictions for J/$\psi$ phase space distributions with the most recent data from the RHIC accelerator. Analysis of the rapidity dependence of the J/$\psi$ nuclear modification factor yields first evidence for the production of J/$\psi$ mesons at the phase boundary. We conclude with predictions for charmonium production at the LHC.Comment: 8 pages, 6 figures, invited paper, Quark Matter 2006 conference, Shanghai, submitted to J. Phys.

Highlights from PHENIX - II

This contribution highlights recent results from the PHENIX Collaboration at RHIC with emphasis on those obtained through lepton and photon measurements in PHENIX.Comment: 9 pages, 13 figures, presented at the 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions - "Quark Matter 2008", Jaipur, India, February 4-10, 200

J/ψ\psi production in In-In and p-A collisions

The NA60 experiment studies dimuon production in In-In and p-A collisions at the CERN SPS. We report recent results on \jpsi production, measured through its muon pair decay. As a function of centrality, we show that in In-In the \jpsi yield is suppressed beyond expectations from nuclear absorption. We present also for the first time results on \jpsi production in p-A collisions at 158 GeV, the same energy of the nucleus-nucleus data. For both p-A and In-In we show preliminary results on \psip suppression. Finally, we have studied the kinematical distributions of the \jpsi produced in In-In collisions. We present results on transverse momentum and rapidity, as well as on the angular distribution of the \jpsi decay products.Comment: 8 pages, Quark Matter 2006 conference proceeding