STAR Heavy Flavor Measurements in Heavy- ion Collisions 1 Outline :  Quarkonia Measurements in  p+p, d+Au and Au+Au collisions  Open Charm Measurement  D meson direct reconstruction.  Non-photonic electron  Summary of the Present Results.  Future STAR Heavy Flavor Program. 06/18/2012UIC HF Workshop 2012 W. Xie for STAR Collaboration (PURDUE University, West Lafayette)

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Quarkonia Suppression: “Smoking Gun” for QGP 3 cc J/  D+D+ d Low temperature Vacuum High temperature High density (screening effect take place) Sequential melting  a QGP thermometer H. Satz, NPA 783 (2007) 249c. d D-D-

The life of Quarkonia in the Medium can be Complicated 4 Observed J/  is a mixture of direct production+feeddown ( R. Vogt: Phys. Rep. 310, 197 (1999)). – All J/  ~ 0.6J/  (Direct) + ~0.3  c + ~0.1  ’ –B meson feed down. 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/   dissociation, i.e. suppression – Recombination from uncorrelated charm pairs D+D+ cc c J/ 

Important to Study Open Heavy Flavor Production A good reference to J/Ψ suppression or enhancement. – Same or similar initial state effect. CGC, Shadowing, initial state energy loss, etc. – Large cross section (compared to J/ψ). Probability for recombination. Accurate reference measurements. One of the important probes complimentary to J/ψ measurements – Interactions between heavy quark and medium are quite different from the ones for light quarks gluon radiation, collisional energy loss, collisional disassociation, etc – allow further understanding of the medium properties. 5

6 The STAR Detector 6 MRPC ToF barrel BBC PMD FPD FMSFMS EMC barrel EMC End Cap DAQ1000 Completed TPC FTPC FGT Ongoing R&D FHC HLT HFT MTD

Signals Observed in STAR 7 STAR can measure heavy flavor of all different kind (J/ψ, D0, D*, electron …) in broad pT range. at both mid and forward rapidity in all collision species. forward J/ψ D 0 Au+Au 200 GeV D* p+p 200 GeV D* p+p 500 GeV

STAR Charmonia Measurements 8 e-/-e-/- e+/+e+/+

J/  Suppression/Enhancement in 200GeV d+A and A+A and Collisions d+Au Collisions: Nice consistency with PHENIX Cu+Cu Collisions:  R AA (p  >5 GeV/c) = 1.4± 0.4±0.2  R AA seems larger at higher pT.  Model favored by data:  2-component: nucl-th/  Incl. color screening, hadron phase dissociation, coalescence, B feeddown.  Model unfavored by the data:  AdS/CFT+Hydro: JPG35,104137(2008) 9 Phys.Rev.C80:041902,2009

R AA vs. p T vs. Npart 10  Consistent with unity at high p T in (semi-) peripheral collisions  Systematically higher at high p T in all centralities  Suppression in central collisions at high p T  System size dependence due to J/  formation time effect?  Escaping at high p T ? See Hao Qiu’s talk this afternoon for details

11 J/ flow: more discriminating power  If charm quark flows. J/Psi from recombination also flow.  If the observation is consistent with zero flow, it could mean  J/psi does not flow OR  Flow is small due to mass ordering effect OR  Recombination is not a dominant process. Yan,Zhuang,Xu PRL 97, (2006) J/  PHENIX NPE v2: arXiv: v2 x y z

J/  spectra in 200GeV Au+Au collisions 12 Broad pT coverage from 0 to 10 GeV/c J/  spectra significantly softer than the prediction from light hadrons  Much smaller radial flow because it’s too heavy?  Regeneration at low p T ? Phys. Rev. Lett. 98, (2007) See Hao Qiu’s talk this afternoon for details

STAR Preliminary J/  elliptic flow v 2 13 disfavors the case that J/Ψ with pT > 2GeV/c is produced dominantly by coalescence from thermalized charm and anti-charm quarks. See Hao Qiu’s talk this afternoon for details

STAR Preliminary The sQGP is Complicated 14 We thus need more probes, other than charms, to have a more complete picture of its properties, e.g. Upslions. Cleaner Probes compared to J/psi:  recombination can be neglected at RHIC Grandchamp, Sun, Van Hess, Rapp, PRC 73, (2006)  Final state co-mover absorption is small. See A. Kesich’s talk for details

A Quick Glimpse of STAR Upsilon Measurements 15  Consistent with the melting of all excited states. Models from M. Strickland and D. Bazow, arXiv: v4 See A. Kesich’s talk for details

STAR Open Charm Measurements 16 D0D0 K+K+  l K-K- e-/-e-/- D0D0

17 D 0 and D* p T spectra in p+p 200 GeV [1] C. Amsler et al. (PDG), PLB 667 (2008) 1. [2] FONLL: M. Cacciari, PRL 95 (2005) arXiv: D 0 scaled by N cc / N D0 = 1 / 0.56 [1] D* scaled by N cc / N D* = 1 / 0.22 [1] Consistent with FONLL [2] upper limit. Xsec = dN/dy| cc y=0 × F ×  pp F = 4.7 ± 0.7 scale to full rapidity.  pp (NSD) = 30 mb

18 D 0 signal in Au+Au 200 GeV  Year 2010 minimum bias 0-80% 280M Au+Au 200 GeV events.  8- signal observed.  Mass = 1863 ± 2 MeV (PDG value is ± 0.4 MeV)  Width = 12 ± 2 MeV YiFei Zhang, JPG 38, (2011)

19 Charm cross section vs N bin Charm cross section follows number of binary collisions scaling => Charm quarks are mostly produced via initial hard scatterings. All of the measurements are consistent. Year 2003 d+Au : D 0 + e Year 2009 p+p : D 0 + D* Year 2010 Au+Au: D 0 Assuming N D0 / N cc = 0.56 does not change. Charm cross section in Au+Au 200 GeV: Mid-rapidity: 186 ± 22 (stat.) ± 30 (sys.) ± 18 (norm.) b Total cross section: 876 ± 103 (stat.) ± 211 (sys.) b [1] STAR d+Au: J. Adams, et al., PRL 94 (2005) [2] FONLL: M. Cacciari, PRL 95 (2005) [3] NLO: R. Vogt, Eur.Phys.J.ST 155 (2008) 213 [4] PHENIX e: A. Adare, et al., PRL 97 (2006) YiFei Zhang, JPG 38, (2011) arXiv:

20 D 0 R AA compared with Alice result YiFei Zhang, JPG 38, (2011)  ALICE results shows D meson is suppressed at high pT.  More luminosity and detector upgrade are needed from STAR to reach high pT.  At present, NPE is the key to study high pT charm and bottom production. A. Rossi, JPG 38, (2011)

Non-photonic Electron Measurements DGLV: Djordjevic, PLB632, 81 (2006) BDMPS: Armesto, et al.,PLB637, 362 (2006) T-Matrix: Van Hees et al., PRL100,192301(2008). Coll. Dissoc. R. Sharma et al., PRC 80, (2009). Ads/CFT: W. Horowitz Ph.D thesis. RL.+ Coll. J. Aichelin et al., SQM11 21  See M. Mustafa talk in the afternoon. STAR: PRL 106, (2011) PHENIX: arXiv: v2

Summary for the STAR Measurements 22  No suppression for J/psi at high p T (5-10 GeV/c) in 200GeV Cu+Cu and peripheral Au+Au collisions,  suppression at high p T in central Au+Au collisions  J/psi suppression at high p T less than that at low p T  J/psi v 2 measurements are consistent with zero, disfavor production at pT > 2 GeV/c dominated by coalescence from thermalized charm quarks  Upsilon measurement are consistent with 2S and 3S state melting.

23  The charm cross section per nucleon-nucleon 200 GeV collision at mid-rapidity  Charm cross sections at mid-rapidity follow number of binary collisions scaling, which indicates charm quarks are mostly produced via initial hard scatterings.  D 0 nuclear modification factor R AA is measured. No obvious suppression observed at p T < 3 GeV/c.  Large suppression of high-pT non-photonic electron production is observed. A real challenge to our understanding of energy loss mechanism. Summary for the STAR Measurements

24 Future of Heavy Flavor Measurement at STAR MTD (MRPC)  See details in Yifei Zhang’s talk next

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26 D 0 signal in p+p 200 GeV B.R. = 3.89% p+p minimum bias 105 M 4- signal observed. Different methods reproduce combinatorial background. Consistent results from two background methods. arXiv:

27 D* signal in p+p 200 GeV Minimum bias 105M events in p+p 200 GeV collisions. Two methods to reconstruct combinatorial background: wrong sign and side band. 8- signal observed. arXiv: