Heavy Flavor Physics at RHIC Matthias Grosse Perdekamp U of Illinois and RIKEN BNL o Overview Selected results from RHIC “light quark” jet quenching and elliptic flow Energy loss of heavy quarks in media as tool to study nuclear media formed in heavy ion collisions.

Heavy Flavor Physics at RHIC: Overview open heavy flavor production spectroscopy: 1) Energy loss in dense and hot nuclear matter 2) Tomography of DHNM 3) Reference data for quarkonia Quarkonia as “Thermometer”: color screening depends on T Matsui and Satz, Phy.Lett. B 178 (1986)416 QGP? A-A PDF(A) p/d-A Modification of PDFs in nuclear environment (anti-) shadowing vs new state of matter (color glass condensate) 2) Reference data for initial state in A-A QCD p-p, d-A, A-A 1) Cross sections vs rapidity and √s 2) Vacuum energy loss vs media 3) Reference data 1) Hadronization mechanism 2) Reference data for quarkonia Polarized PDFs p-p measure formation process?

Polarized pp: ΔG from charm production Double spin asymmetry electron asymmetry for charm production (I. Bojak and M. Stratmann, hep-ph/0112276) Scale dependence reduced at NLO: LO NLO

Relativistic Heavy Ion Collider Design Parameters: Performance Au + Au p+p snn 200 GeV 500 GeV L [cm-2 s -1 ] 2 x 1026 2 x 1032 Cross-section 7 barns 60 mbarn Interaction rates 14 kHz 12 MHz RHIC Capabilities Au + Au collisions at 200 GeV/u p + p collisions up to 500 GeV spin polarized protons (70%) lots of combinations in species and energy in between

RHIC Running 2 x design Luminosity! Delivered 1196 (mb)-1 to Phenix [week ago : 1060] 136 (mb)-1 last week [best week: 158] 2 x design Luminosity! maximum projection physics target minimum projection

Charm and J/ψ Data from RHIC Run I, 2001 Au-Au beams at s=130 GeV Open charm from PHENIX Run II, 2002 Au-Au beams and p-p at s=200 GeV Open charm and J/Y from PHENIX Run III, 2003 d-Au, p-p at s=200 GeV Open charm from PHENIX and STAR, J/Y from PHENIX Run IV, 2004 Au-Au, s=200 GeV More measurements to come

STAR: Large acceptance TPC+EMC

Au-Au Event in STAR Das man in diesen Kollisionen ueberhaupt irgentetwas lehren kann ist ein Wunder in sich. Hier ist eine Au-Au kollision aufgezeichnet mit STAR experiment am RHIC. Sie sehen tausende von Teilchen in der Spurkammer von STAR. Und daraus gilt es nun was zu lernen. Und mit vielen Jahren Erfahrung ist dies tatsachlich moeglich!

PHENIX Physics Capabilities designed to measure rare probes: + high rate capability & granularity + good mass resolution and particle ID - limited acceptance Au-Au & p-p spin 2 central arms: electrons, photons, hadrons charmonium J/, ’ -> e+e- vector meson r, w,  -> e+e- high pT po, p+, p- direct photons open charm hadron physics 2 muon arms: muons “onium” J/, ’,  -> m+m- vector meson  -> m+m- combined central and muon arms: charm production DD -> em global detectors forward energy and multiplicity event characterization

Au-Au and d-Au events in the PHENIX Central Arms

Open charm in pp: Single electrons d + Au STAR Preliminary charm cross sections (barely) agree! PHENIX PRELIMINARY =1.36 ± 0.20 ± 0.39 mb PHENIX: three methods to subtract photonic background STAR: three methods to identify electrons

Consistency between electron data sets STAR slightly above PHENIX

Does the PYTHIA “extrapolation” work? PYTHIA tuned to available data (sNN < 63 GeV) prior to RHIC results 1Phys. Rev. Lett. 88, 192303 (2002) PHENIX PRELIMINARY STAR preliminary spectra are harder than PYTHIA extrapolation from low energies Use parametrization for Au-Au reference Use rapidity dependence from PYTHIA to extract cross section

STAR preliminary Reconstruction of D mesons in dAu Collisions D0+D0 0 < pT < 3 GeV/c, |y| < 1.0 d+Au minbias = 1.12 ± 0.20 ± 0.37 mb from D data (1.36 ± 0.20 ± 0.39 mb with electrons)

Collision Geometry -- “Centrality” Spectators Participants For a given b, Glauber model predicts Npart (No. participants) and Nbinary (No. binary collisions) 15 fm b 0 fm 0 Npart 394 0 Nbinary 1200

Experimental Determination of Centrality BBC Au ZDC ZDC ZDC: zero degree calorimeter BBC: beam-beam counter

Selected Results: Elliptic Flow Origin: spatial anisotropy of the system when created, followed by multiple scattering of particles in the evolving system spatial anisotropy  momentum anisotropy v2: 2nd harmonic Fourier coefficient in azimuthal distribution of particles with respect to the reaction plane Almond shape overlap region in coordinate space Outgoing particle

E. Shuryak

STAR v2 for charged particles Large v2 STAR v2 for charged particles Hydrodynamic limit exhausted at RHIC for low pT particles. Large magnitude of v2 suggests highly viscous “liquid”: strongly interacting nuclear medium has been formed! Adler et al., nucl-ex/0206006

Probing the nuclear medium formed: Jet Suppression charm/bottom dynamics J/Y & U direct photons CONTROL

Light qs and g jets as probe of the medium hadrons q leading particle leading particle schematic view of jet production Jets from hard scattered quarks observed via fast leading particles or azimuthal correlations between the leading particles However, before they create jets, the scattered quarks radiate energy (~ GeV/fm) in the colored medium Decreases their momentum (fewer high pT particles) Eliminates jet partner on other side Jet Quenching

Quantify Nuclear Modification of Hadron Spectra 1. Compare Au+Au to nucleon-nucleon cross sections 2. Compare Au+Au central/peripheral Nuclear Modification Factor: nucleon-nucleon cross section <Nbinary>/sinelp+p AA AA If no “effects”: R < 1 in regime of soft physics R = 1 at high-pT where hard scattering dominates Suppression: R < 1 at high-pT AA AA AA AA

Quantitative Agreement across Experiments Effect is real…Final or Initial State Effect?

Centrality Dependence Au-Au vs d-Au Au + Au Experiment d + Au Control Experiment Final Data Preliminary Data Significantly different and opposite centrality evolution of Au+Au experiment from d+Au control. Jet Suppression is clearly a final state effect.

Heavy Quark Energy Loss in Media Shuryak proposed that charm quarks may suffer a large energy loss when propagating through a high opacity plasma, leading to large suppression of D mesons. (E. V. Shuryak, Phys. Rev. C 55, 961 (1997) Dokshitzer and Kharzeev propose the “dead cone” effect: Reduced gluon emission at small angles in media for heavy quarks may lead to enhancement in D meson production. Y.L. Dokshitzer and D. E. Kharzeev, Phys. Lett. B 519, 199 (2001) 2003 Djordjevic and Gyulassy: detailed quantitative treatment of heavy quark energy loss in strongly interacting media. Predict slight suppression: 0.6-0.8! M. Djordjevic and M. Gyulassy, nucl-th/0310076

Radiative heavy quark energy loss from Magdalena Djordjevic at QM 2004 There are three important medium effects that control the radiative energy loss at RHIC Ter-Mikayelian effect (Djordjevic-Gyulassy Phys.Rev.C68:034914,2003) Transition rediation (Zakharov) Energy loss due to the interaction with the medium Ter-Mikayelian: QCD analog to dielectric effect in electrodynamics 1) 2) 3)

Centrality dependence in AuAu 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] pp reference pp reference 1/TAA 1/TAA 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] 1/TABEdN/dp3 [mb GeV-2] 1/TAA 1/TAA 1/TABEdN/dp3 [mb GeV-2] 1/TAA pp reference pp reference pp reference No deviations from binary scaling within uncertainties. Consistent with Djordjevic and Gyulassy: 10 x more data from Run 2004!

Centrality dependence in dAu PHENIX PRELIMINARY 1/TAB 1/TABEdN/dp3 [mb GeV-2] PHENIX PRELIMINARY 1/TABEdN/dp3 [mb GeV-2] Single electron spectra in dAu are in good agreement with the proton reference.

Charm flow? is partonic flow realized? PHENIX PRELIMINARY is partonic flow realized? v2 of non-photonic electrons indicates non-zero charm flow in AuAu collisions uncertainties are large definite answer: RUN-04 AuAu data sample!

J/Y: Does colored medium screen cc ? 40-90% most central Ncoll=45 20-40% most central Ncoll=296 0-20% most central Ncoll=779 Statistics limited: Run 2004! R.L. Thews, M. Schroedter, J. Rafelski Phys. Rev. C63 054905 (2001): Plasma coalesence model for T=400MeV and ycharm=1.0,2.0, 3.0 and 4.0. L. Grandchamp, R. Rapp Nucl. Phys. A&09, 415 (2002) and Phys. Lett. B 523, 50 (2001): Nuclear Absorption+ absoption in a high temperature quark gluon plasma A. Andronic et. Al. Nucl-th/0303036 Proton

Summary The final state produced in central Au-Au collisions at RHIC is dense and opaque and appears to have the properties of a strongly interaction liquid. The energy loss of heavy quarks in nuclear media is an important tool to further characterize the nature of the medium produced at RHIC. Heavy flavor production will play an important role in studying nucleon structure in d-A and polarized p-p collisions at RHIC. The experimental possibilities will be greatly enhanced by silicon vertex detector upgrades for PHENIX and STAR. We expect a significant qualitative and quantitative advance from run 2004 in understanding the nature of the matter formed in central collisions at RHIC.

PHENIX: J/Ye+e- and m+m- from pp s= 3.99 +/- 0.61(stat) +/- 0.58(sys) +/- 0.40(abs) mb (BR*stot = 239 nb) Central and forward rapidity measurements from Central and Muon Arms: Rapidity shape consistent with various PDFs √s dependence consistent with various PDFs with factorization and renormalization scales chosen to match data Higher statistics needed to constrain PDFs

PHENIX: J/Ye+e- and m+m- from pp pT shape consistent with COM over our pT range Higher statistics needed to constrain models at high pT Polarization measurement limited