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Measurement of Heavy Flavor Production in STAR Experiment at RHIC. W. Xie for STAR Collaboration (Purdue University, West Lafayette). l. Motivation for Studying Heavy Quarks. Heavy quark mass are external parameter to QCD. Sensitive to initial gluon density and gluon distribution.
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Measurement of Heavy Flavor Production in STAR Experiment at RHIC W. Xie for STAR Collaboration (Purdue University, West Lafayette) Strong Interaction In The 21st Century, TIFR, 2010
l Motivation for Studying Heavy Quarks • Heavy quark mass are external parameter to QCD. • Sensitive to initial gluon density and gluon distribution. • Interact with the medium differently from light quarks. • Suppression or enhancement pattern of heavy quarkonium production reveal critical features of the medium. • Cold Nuclear effect (CNM): • Different scaling properties in central and forward rapidity region CGC. • Gluon shadowing, etc K+ e-/- K- Non-photonic electron D0 Open heavy flavor e-/- e+/+ Heavy quarkonia
The larger the energy loss The smaller the RAA Some Variables to quantify the medium effect RAA ( or RdA) “no effect” No medium effect 5 N+N coll. in 1 A+A coll. • Heavy quarks are from Hard collision: • Each collision is separated clearly. • In the absence of any nuclear effect, • Yield(A+A) = yield(p+p)*N(collisions), i.e. scale with number of collisions (Ncoll)
The STAR Detector MTD EMC barrel MRPC ToF barrel EMC End Cap FMS BBC FPD TPC FHC PMD Completed DAQ1000 HLT Ongoing R&D HFT FGT
STAR hadrons pT> 6 GeV/c Measurements on Non-photonic Electron RAA • large suppression of heavy quark production is observed
u u u light K+ c l l l D0 K+ Hot/Dense Medium c quark e-/- c D0 D0 meson energy loss Ivan, et al The Large Suppression was a Surprise K+ Hot/Dense Medium “dead cone effect”: gluon radiation suppressed at q< mQ/EQ c quark e-/- c D0 radiative energy loss (D. kharzeev, M.Djordjevicet al. ) Hot/Dense Medium c quark e-/- collision energy loss (Teany, Ralf, Denes et al.)
Do we Understand the Result? PHENIX nucl-ex/0611018 STAR nucl-ex/0607012 • Radiative Energy Loss with reasonable gluon densities do not explain the observed suppression • Djordjevic, PLB632 81 (2006) • Armesto, PLB637 362 (2006) • Collisional EL may be significant for heavy quarks • Wicks, nucl-th/0512076 • Van Hess, PRC 73 034913 (2006) • Van Hess PRL 100, 192301(2008). • heavy quarks fragment inside the medium and are suppressed by dissociation? • Adil and Vitev, hep-ph/0611109 • Similar suppression for B and D at high-pT Possible Key to the solution: Separate charm and bottom measurements
Disentangle Charm and Bottom Production B • wider φ distribution for B meson because of the larger mass. • Combined fit on data to obtain the B meson contribution to non-photonic electron. D X.Y. Lin, hep-ph/0602067
Disentangle Charm and Bottom Production STAR preliminary JPG35(2008)104117 JPG35(2008)104117 • near side: mostly from B mesons • Away side: charm (~75%), Bottom (~25%)
B Quark contribution is Significant Star preliminary Nuclear Physics A830 (2009)849c ~30-60% of non-photonic electron come from B meson decay.
Disentangle Charm and Bottom Quark Energy Loss S. Sakai : SQM08 pT > 5 GeV/c I: Djordjevic et al, PLB 632 (2006) 81; dNg/dy = 1000 II: Adil et al, PLB 649 (2007) 139 III: Hees et al, PRL. 100 (2008) 192301
c c d Quarkonia Suppression: “smoking gun” for QGP Physics Letter B Vol.178, no.4 1986 • Low temperature • Vacuum J/y • High temperature • High density • (screening effect take place) d D- D+ The melting sequence: cc -> Y’ -> J/y -> Upsilon
c c c The life of Quarkonia in the medium can be complicated • Observed J/y is a mixture of direct production+feeddown. • All J/y ~ 0.6J/y(Direct) + ~0.3 cc + ~0.1y’ • Important to disentangle different component • Suppression and enhancement in the “cold” nuclear medium • Nuclear Absorption, Gluon shadowing, initial state energy loss, Cronin effect and gluon saturation (CGC) • Hot/dense medium effect • J/y, dissociation, i.e. suppression • Recombination from uncorrelated charm pairs • Survival (or not) in the hot/dense medium from lattice calculation J/y D+
Quarkonia Signals in STAR arXiv:1001.2745 STAR Preliminary STAR Preliminary STAR Preliminary STAR Preliminary STAR Preliminary • STAR can measure Quarkonia • of all different kind (,J/ψ, χc, …) • in all pT range. • at both mid and forward rapidity • in all collision species. forward J/ψ J/ψ from χc enriched
J/y Production in 200GeV p+p collisions • Color singlet model (NNLO*CS): • P. Artoisenet et al., PRL. 101, 152001 (2008), and J.P. Lansberg private communication. • Include no feeddown from higher mass state. • LO CS+ color octet (CO): • G. C. Nayak et al., PRD 68, 034003 (2003), and private communication. • Include no feeddown from higher mass state. • Agree with the data • Color Evaporation Mode: • M. Bedjidian et al., hep-ph/0311048; R. Vogt private communication • Include feeddown from Xc and ψ’ • Agree with the data Phys.Rev.C80:041902,2009
J/y-hadron Azimuthal Correlation in 200GeV p+p Collisions Phys.Rev.C80:041902,2009 • Constrain B meson yield through BJ/y: (13 ± 5) % of total J/y (pT>5GeV/c) • Constrain J/y Production mechanisms in p+p: • J/y+c, J/y+D or J/y+e • S. Brodsky, J.-P. Lansberg, arXiv:0908.0754
J/y Suppression/enhancement in 200GeV A+A Collisions Au+Au Collisions: • Nice agreement with PHENIX Cu+Cu Collisions: • RAA(p>5 GeV/c) = 1.4± 0.4±0.2 • RAA seems larger at higher pT. • Model favored by data: • 2-component: nucl-th/0806.1239 • Incl. color screening, hadron phase dissociation, coalescence, B feeddown. • Model unfavored by the data: • AdS/CFT+Hydro: JPG35,104137(2008) • Comparison with open charm: • Charm quark & Heavy resonance : NPA784, 426(2007); PLB649, 139 (2007), and private communication Star preliminary Au+Au: 0-80% Phys.Rev.C80:041902,2009
Production in 200GeV p+p Collisions arXiv:1001.2745 arXiv:1001.2745 arXiv:1001.2745 pb
RdAu ( ) in 200GeV d+Au Collisions NPA830(2009)235c NPA830(2009)235c nb
Future of Heavy Flavor Measurement at STAR MTD (MRPC) Courtesy of T. Ullirich
Summary and Perspective • Heavy flavor Studies at RHIC is at its early stage • Expecting exciting results in the coming years with upgraded detectors and luminosity.
Non-photonic e-h correlations in Au+Au 200 GeV STAR Preliminary Au+Au: 0-20% 3 < pTtrig< 6 GeV/c && 0.15 < pTasso< 1.0 GeV/c
Discrepancy between STAR and PHENIX • A factor of two difference between STAR and PHENIX • In high pT yield • Total cross section • in all collision species. • STAR New Measurements in p+p collision will come out soon.
Forward Meson Spectrometer (FMS) • 20x more acceptance than previous forward detectors at STAR • Full azimuthal coverage for 2.5 < η < 4 FPD FMS • Increased acceptance not only increases pion yields and kinematic range but also gives much higher geometric efficiency for high-xF J/ψ Geometric Efficiency: J/ψ xF Chris Perkins
J/y Suppression in Au+Au collisions CNM: sabs = 1-3 mb 1 RAA Bar: uncorrelated error Bracket : correlated error 0 1 RAA (1.2<|y|<2.2)/RAA (|y|<0.35) 0 • Larger suppression in forward rapidity comparing to midrapidity. • CNM suppression can not explain the results in Au+Au collisions
NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) PHENIX at RHIC (1.2<|y|<2.2) NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) PHENIX at RHIC (1.2<|y|<2.2) NA50 at SPS (0<y<1) PHENIX at RHIC (|y|<0.35) NA50 at SPS (0<y<1) NA50 (0<y<1) NA50 (0<y<1) NA50 (0<y<1) Bar: uncorrelated error Bracket : correlated error Global error = 12% and Global error = 7% are not shown Bar: uncorrelated error Bracket : correlated error Global error = 12% is not shown Normalized by NA51 p+p data with correction based on Eur. Phys. J. C39 (2005) : 355 Comparing RHIC to SPS Suppression results • After removing the CNM effect, differences start to show-up. • suppression at SPS consistent with the melting of psi’ and chi_c? • Need more precise d+Au measurements • Suppression pattern similar in RHIC and SPS. • CNM effect not removed yet.
Do we understand J/y results Rapp direct Rapp direct Capella 1mb Capella 1mb Capella 3mb Capella 3mb Satz (w/ CNM) • Models that include only anomalous suppression predict too much suppression for RHIC mid-rapidity • Satz - color screening in QGP with CNM added (EKS shadowing + 1 mb) • Capella – comovers with normal absorption and shadowing • Rapp – direct production with CNM effects (without regeneration) • Models including both suppression and recombination match data better • R. Rapp(for y=0) PRL 92, 212301 (2004) • Thews (for y=0) Eur. Phys. J C43, 97 (2005) • Nu Xu et al. (for y=0) nucl-th/0608010 • Bratkovskaya et al. (for y=0) PRC 69, 054903 (2004) • A. Andronic et al. (for y=0) nucl-th/0611023 • All seems to be somewhat more consistent with the data. • Other sensitive comparisons are needed
Flow of electrons from Charm and Bottom meson decay [Phys.Lett. B595 202-208 ] [PRC72,024906] [PRC73,034913] [PRB637,362] • Strong elliptic flow for non-photonic electron • Main source is D meson -> indicate non-zero D v2 • Charm v2 also non-zero ? • Bottom sneak in here?
LO NLO NNLO PRL 101, 152001