Measurement of Open Heavy Flavor Production with Single Muons in p+p and d+Au Collisions at RHIC

Heavy flavor production in hadronic collisions is dominated by gluonic processes and so is a sensitive probe of the gluon structure function in the nucleon and its modification in nuclei. A study of heavy flavor production in p+p and d+Au collisions in various kinematic regions presents an opportunity to probe cold nuclear medium effects; parton shadowing, color glass condensate, initial state energy loss, and coherent multiple scattering in final state interactions. The PHENIX muon arms cover both forward and backward directions in the rapidity range of $1.2 < |\eta| < 2.4$. We investigate single muon production from open heavy flavor and light mesons decay in p+p and d+Au collisions at forward and backward rapidity.Comment: Strangeness in Quark Matter, 2006, UCL

Direct photons at low pTp_{T} measured in PHENIX

Direct photon spectra measured at small $p_T$ in p+p, d+Au and Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV are presented. Several measurement techniques including statistical subtraction, tagging, and internal and external conversion were applied and found to produce consistent results. The p+p and d+Au results are found to be in very good agreement with pQCD predictions over the entire $p_T$ range. No excess of direct photons in Au+Au collisions with respect to binary scaled d+Au data is observed within systematic errors.Comment: 4 pages, 3 figures, proceedings for Quark Matter 200

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

The azimuthal anisotropy of electrons from heavy flavor decays in sqrt(s_NN) = 200 GeV Au-Au collisions by PHENIX

The transverse momentum dependence of the azimuthal anisotropy parameter v_{2}, the second harmonic of the azimuthal distribution, for electrons at mid-rapidity (|eta|<0.35) has been measured with the PHENIX detector in Au+Au collisions at sqrt(s_NN) = 200 GeV with respect to the reaction plane defined at high rapidities (|eta|=3-4). From the result we have calculated non-photonic electron v_{2}, which is expected to reflect the heavy-flavor azimuthal anisotropy, by subtracting v_{2} of electrons from other sources such as photon conversions, Dalitz decay etc.Comment: 4 pages, 4 figures, proceeding (poster) of the 18th International Conference on Nucleus-Nucleus Collisions (QM2005), Aug.4-9, Budapest, Hungar

The PHENIX measurement of Heavy Flavor via Single Electrons in pp, d-Au, and Au-Au collisions at sqrt(s_NN)=200 GeV

The PHENIX experiment at RHIC has measured single electron spectra in proton-proton, deuteron-gold and gold-gold collisions at sqrt(s_NN)=200 GeV. The photonic contribution (photon conversions and Daltiz decays) is subtracted from the inclusive spectra resulting in non-photonic electron spectra. The principal source of non-photonic electrons is the semi-leptonic decay of charm and bottom mesons. The implications for heavy flavor production in hot and cold nuclear systems are discussed.Comment: 4 pages, 4 figures, contribution to the proceedings of the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter 2004

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

Evolution of the Away-Side Jet Shapes in pi0-h Correlations in 200 GeV Au+Au Collisions with RHIC-PHENIX

Two-particle azimuthal correlations have allowed detailed study of the modification to di-jets in the hot, dense medium created in RHIC collisions. Light can be shed by such correlations on many novel effects discovered at RHIC such as the enhanced p/pi ratio and conical structure of events with energy loss. Using pi0 triggers to reduce the effect of recombination we utilize high-pT correlations to explore the away-side structure.Comment: 5 pages, 3 figures, poster presented at the 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (QM2006

Probing gluon polarization with pi0's in longitudinally polarized proton collisions at the RHIC-PHENIX experiment

This report presents double helicity asymmetry in inclusive $\pi^0$ production in polarized proton-proton collisions at a center-of-mass energy ($\sqrt{s}$) of 200 GeV. The data were collected with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC) during the 2004 run. The data are compared to a next-to-leading order perturbative quantum chromodynamic (NLO pQCD) calculation.Comment: 4pp. To appear in the proceedings of 16th International Spin Physics Symposium (SPIN 2004), Trieste, Italy, 10-16 Oct 200

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