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Charm Production from STAR Experiment

W. Xie for STAR Collaboration (PURDUE University, West Lafayette). Charm Production from STAR Experiment. Outline : STAR Present Measurements J/ ψ Measurements in p+p , d+Au and Au+Au collisions Open Charm Measurement D meson direct reconstruction. Non-photonic electron

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Charm Production from STAR Experiment

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  1. W. Xie for STAR Collaboration (PURDUE University, West Lafayette) Charm Production from STAR Experiment • Outline: • STAR Present Measurements • J/ψ 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. Berkeley School 2012

  2. 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 reveals 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

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

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

  5. Important to Study Open Charm 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). • 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.

  6. The STAR Detector EMC barrel MTD MRPC ToF barrel EMC End Cap FMS BBC FPD TPC FHC PMD FTPC Completed DAQ1000 Ongoing R&D HFT FGT HLT 7

  7. The (major) STAR Detector for Charm Measurements • Time Projection Chamber: • , full azimuth • Tracking. • PID through dE/dx • Barrel Electromagnetic Calorimeter • , full azimuth • BTOW: • Tower: • p/E for electron ID • Fast online trigger • BSMD: • Double layer High spatial resolution MWPC. • e/h separation. • Time of Flight: • , full azimuth . • PID through TOF • Timing resolution: ~85 ps. 8

  8. |1/-1|<0.03 Particle Identification from TOF+dE/dx • Extend hadron PID to intermediate pT • Important for open charm measurements. • TOF/TPC allows electron PID down to very low momentum • Important for charmonia measurements.

  9. Electron Identification from TPC + BEMC 2.5 < pT<3.0 GeV/c 8.0< pT<10 GeV/c • High pT electron PID: • TPC+BTOW: • Associate TPC tracks with BTOW clusters. • cut p/E ~1.0 • Cut on number of BSMD strips per cluster: • Associate TPC tracks with BSMD clusters. • Higher for electron.

  10. Charm Signals Observed in STAR STAR Preliminary • STAR can measure charm • of all different kind • (J/ψ, D0, D*, electron …) • in broad pTrange. • at both mid and forward rapidity • in all collision species. STAR Preliminary D* p+p 200 GeV D0Au+Au 200 GeV forward J/ψ D* p+p 500 GeV J/ψ from χc enriched

  11. STAR Charmonia Measurements e-/- e+/+

  12. J/y Production in 200GeV p+p Collisions Zebo Tang, JPG 38, 124107 (2011) • 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 Model: • M. Bedjidian et al., hep-ph/0311048; R. Vogt private communication • Include feeddown from Xc and ψ’ • Agree with the data STAR: Phys. Rev. C80, 041902(R) (2009) Tsallis Blast-Wave model: ZBT et al., arXiv:1101.1912; JPG 37, 085104 (2010)

  13. J/y-hadron Azimuthal Correlation in 200GeV p+p Collisions Zebo Tang, JPG 38, 124107 (2011) • BJ/y: 10-20% of total J/y (pT > 4GeV/c) at RHIC • The ratio has no significant dependence on collisions energy. • 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

  14. Away side associated hadron pT spectra Consistent with hadron-hadron correlation away-side seems to come from gluon/light quark fragmentation Zebo Tang, JPG 38, 124107 (2011) STAR, PRL95, 152301 (2005) E. Braaten Phys. Rev. Lett. 71, 1673 (1993).

  15. J/y Polarization Helicity frame See Barbara Trzeciak’stalk for details. pT (J/psi: GeV/c) • On top of spectra, J/psi polarization provide additional discrimination power against models. • Results are consistent with the COM and NLO+ CSM prediction. • Much more statistics are needed.

  16. J/y Suppression/Enhancement in 200GeV d+A and A+A and Collisions d+Au Collisions: • Nice consistency 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 Phys.Rev.C80:041902,2009

  17. J/y spectra in 200GeV Au+Au collisions Zebo Tang, JPG 38, 124107 (2011) • Broad pT coverage from 0 to 10 GeV/c • J/y spectra significantly softer than the prediction from light hadrons • Much smaller radial flow? • Regeneration at low pT? Phys. Rev. Lett. 98, 232301 (2007) Tsallis Blast-Wave model: ZBT et al., arXiv:1101.1912; JPG 37, 085104 (2010)

  18. RAA vs. pT Zebo Tang, JPG 38, 124107 (2011) STAR CuCu: PRC80, 014922(R) PHENIX: PRL98, 232301 Yunpeng Liu, Zhen Qu, Nu Xu and Pengfei Zhuang, PLB 678:72 (2009) and private comminication Xingbo Zhao and Ralf Rapp, PRC 82,064905(2010) and private communication Increase from low pT to high pT Consistent with unity at high pT in (semi-) peripheral collisions More suppression in central than in peripheral even at high pT Zebo Tang, JPG 38, 124107 (2011)

  19. RAA vs. Npart Zebo Tang, JPG 38, 124107 (2011) Systematically higher at high pTin all centralities Suppression in central collisions at high pT System size dependence due to J/y formation time effect? Escaping at high pT (without jet quenching effect)? Yunpeng Liu, Zhen Qu, Nu Xu and Pengfei Zhuang, PLB 678:72 (2009) and private comminication Xingbo Zhao and Ralf Rapp, PRC 82,064905(2010) and private communication STAR Pion: Yichun Xu at QM2009

  20. J/ z y x Yan,Zhuang,Xu PRL 97, 232301 (2006) J/y flow: more discriminating power PHENIX NPE v2: arXiv:1005.1627v2 • 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.

  21. J/y elliptic flow v2 Zebo Tang, JPG 38, 124107 (2011) STAR Preliminary • V2 (hadron) > V2 (Φ) > v2 (J/ψ) ~0. • Is it completely due to mass ordering effect?

  22. J/y elliptic flow v2 Zebo Tang, JPG 38, 124107 (2011) Courtesy of HaoQiu STAR Preliminary [1] V. Greco, C.M. Ko, R. Rapp, PLB 595, 202. [2] L. Ravagli, R. Rapp, PLB 655, 126. [3] L. Yan, P. Zhuang, N. Xu, PRL 97, 232301. [4] X. Zhao, R. Rapp, 24th WWND, 2008. [5] Y. Liu, N. Xu, P. Zhuang, Nucl. Phy. A, 834, 317. [6] U. Heinz, C. Shen, priviate communication. disfavors the case that J/Ψ with pT > 2GeV/c is produced dominantly by coalescence from thermalized charm and anti-charm quarks.

  23. l STAR Open Charm Measurements K+ e-/- D0 K- + D0

  24. D0 signal in p+p 200 GeV arXiv:1204.4244. B.R. = 3.89% p+p minimum bias 105 M 4-s signal observed. Different methods reproduce combinatorial background. Consistent results from two background methods. 25

  25. D* signal in p+p 200 GeV arXiv:1204.4244. • Background recomstruction: • Wrong sign: • D0 and -, and + • Side band: • 1.72< M(K) < 1.80 or • 1.92 < M(K) < 2.0 GeV/c2 • Minimum bias 105M events in p+p 200 GeV collisions. • Two methods to reconstruct combinatorial background: wrong sign and side band. • 8-s signal observed. 26

  26. D0 and D* pT spectra in p+p 200 GeV D0 scaled by Ncc/ND0 = 1 / 0.56[1] D* scaled by Ncc/ND* = 1 / 0.22[1] Consistent with FONLL[2] upper limit. Xsec = dN/dy|ccy=0 × F × spp F = 4.7 ± 0.7 scale to full rapidity. spp(NSD) = 30 mb arXiv:1204.4244. [1] C. Amsler et al. (PDG), PLB 667 (2008) 1. [2] FONLL: M. Cacciari, PRL 95 (2005) 122001. • The charm cross section at mid-rapidity is: • The charm total cross section is extracted as: • b | 27

  27. D0 signal in Au+Au 200 GeV YiFei Zhang, JPG 38, 124142 (2011) • Year 2010 minimum bias 0-80% 280M Au+Au 200 GeV events. • 8-s signal observed. • Mass = 1863 ± 2 MeV (PDG value is 1864.5 ± 0.4 MeV) • Width = 12 ± 2 MeV 28

  28. Charm cross section vsNbin YiFei Zhang, JPG 38, 124142 (2011) arXiv:1204.4244. All of the measurements are consistent. Year 2003 d+Au : D0 + e Year 2009 p+p : D0 + D* Year 2010 Au+Au: D0 Assuming ND0 /Ncc = 0.56 does not change. Charm cross section in Au+Au 200 GeV: Mid-rapidity: 186 ± 22 (stat.) ± 30 (sys.) ± 18 (norm.) mb Total cross section: 876 ± 103 (stat.) ± 211 (sys.) mb [1] STAR d+Au: J. Adams, et al., PRL 94 (2005) 62301 [2] FONLL: M. Cacciari, PRL 95 (2005) 122001. [3] NLO:  R. Vogt, Eur.Phys.J.ST 155 (2008) 213    [4] PHENIX e: A. Adare, et al., PRL 97 (2006) 252002. Charm cross section follows number of binary collisions scaling => Charm quarks are mostly produced via initial hard scatterings. 29

  29. Charm cross section vs√sNN YiFei Zhang, JPG 38, 124142 (2011) Compared with other experiments, provide constraint for theories. 30

  30. D0 RAA compared with Alice result YiFei Zhang, JPG 38, 124142 (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, 124139 (2011) 31

  31. 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, 054902(2009). Ads/CFT: W. Horowitz Ph.D thesis. RL.+ Coll. J. Aichelin et al., SQM11 Charm dominate at pT<5 GeV/c STAR: PRL 106, 159902 (2011) PHENIX: arXiv:1005.1627v2 • Models with different or similar mechanisms can or can not describe the data • Which one is right and what are missing?

  32. Summary for the Present STAR Charmonia Measurements • In p+p collisions • J/y spectra measurements are extended to high pT • J/y polarization is consistent with COM and NLO+ CSM prediction • Large S/B ratio allows correlation study • B has sizeable (not dominant) contribution at high pT • High-pT J/y away side hadron production consistent with gluon / light quark fragmentation • In heavy-ion collisions • Observation of no suppression for J/y at high pT (5-10 GeV/c) at STAR in 200GeV Cu+Cu and peripheral Au+Au collisions, and suppression at high pT in central Au+Au collisions J/y suppression at high pT less than that at low pT • J/yv2 measurements are consistent with zero, disfavor production at pT > 2 GeV/c dominated by coalescence from thermalized charm quarks

  33. Summary for the Present STAR Open Charm Measurements • D0and D* are measured in p+p 200 GeV up topT = 6 GeV/c. • D0 is measured in Au+Au 200 GeV up topT = 5 GeV/c. • 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. • D0 nuclear modification factor RAA is measured. No obvious suppression observed at pT < 3 GeV/c. • Large suppression of high-pT non-photonic electron production is observed. • A real challenge to our understanding of energy loss mechanism. | | 34

  34. The sQGP is Complicated 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, 064906 (2006) • Almost no feeddown for Upsilon • Final state co-mover absorption is small. STAR Preliminary STAR Preliminary STAR Preliminary Anthony Kesich, WWnd2012

  35. A Quick Glimpse of STAR Upsilon Measurements • S. Digal, P. Petreczky, and H. Satz, • PhysRev. D 64,094015 (2001) Anthony Kesich, WWnd2012 0-10% Centrality STAR Preliminary • Consistent with the melting of all excited states.

  36. Questions to be addressed by STAR in the next Decade. (http://www.bnl.gov/npp/docs/STAR_Decadal_Plan_Final%5B1%5D.pdf)

  37. How to address these questions At both low pT and high pT

  38. Heavy Flavor Tracker (HFT) HFT SSD IST PXL Inner Field Cage • PIXEL • double layers • 18.4x18.4 m pixel pitch • 2 cm x 20 cm each ladder • 10 ladders, delivering ultimate pointing resolution. • new active pixel technology Magnet Return Iron FGT Outer Field Cage • SSD • existing single layer detector, double side strips (electronic upgrade) • IST • one layer of silicon strips along beam direction, guiding tracks from the SSD through PIXEL detector. - proven strip technology • Prototype for run2013 and complete for run2014 TPC Volume Solenoid EAST WEST

  39. Muon Telescope Detector (MTD) • Use the magnet steel as absorber and TPC for tracking. • covers thewhole iron bars and leave the gaps in-between uncovered. • Acceptance: ||<0.5 and 45% in azimuth • 118 modules, 1416 readout strips, 2832 readout channels • Long-MRPC detector technology, • HPTDCelectronics (same as STAR-TOF) ~43% for run2013 and Complete for run2014

  40. RHIC CAD Projections http://www.bnl.gov/npp/docs/pac0611/Fischer_Machine%20performance%20and%20projections.pdf

  41. Production and flow of Directly Reconstructed Charm RCP=a*N10%/N(60-80)% • Assuming D0Rcp distribution as charged hadron • Assuming D0 v2 distribution from quark coalescence. • 500M minbias events. • STAR duty factor: 50% (underestimated). • Efficiency of |Vz|<5cm: 20%. • 50 kHz collision rate at RHIC-II and 500 Hz bandwidth for minbias trigger

  42. Access Bottom Production via Electrons Curves:  H. van Hees et al. Eur. Phys. J. C 61 (2009) 799 • (Be) spectra obtained via the subtraction of charm decay electrons from inclusive NPEs: no model dependence • 500M minbias events for low pT • 500 µb-1 sampled Luminosity for high pT • corresponding to 5 nb-1 RHIC delivered luminosity

  43. BJ/ + X with HFT+TPC+MTD Prompt J/ J/ from B • Cleanest sample of B meson decays. • BJ/ψee suffer from low trigger efficiency. • A much better measurements: BJ/ψ->µµ • not limited by triggers • Less multiple scattering, leading to higher B meson ID efficiency. • One RHIC-II run, ~3000 counts in Au+Au and 200 counts in p+p

  44. Upsilon Mass Resolution with MTD Di-electrons without inner tracker. Di-muonsfrom any case Di-electrons with inner tracker • Before run013, • will provide us with the initial clue on Upsilon production. • After run013, • will tell us in detail how Upsilon is produced. • With detector upgrade and much more luminosity

  45. J/µµ J/µµ Projections on J/ψ Measurements (delivered) (delivered) Zebo Tang, JPG 38, 124107 (2011)

  46. Projections on Upsilon Measurements • Good accuracy in inclusive in each centrality. • Good accuracy in inclusive in each centrality. • Capable of separating 1S/(2S+3S) states.

  47. Charm Baryons • cpK Lowest mass charm baryons c = 60 m • c/D enhancement? • 0.11 (pp PYTHIA)  0.4-0.9 (Di-quark correlation in QGP) S.H. Lee etc. PRL 100 (2008) 222301 • Total charm yield in heavy ion collisions

  48. QGP Thermal Radiation with dileptons J. Zhao, JPG 38, 124134 (2011) L. Ruan et al., JPG 36 (2009) 095001 • QGP thermal radiations • dominated by the correlated pair from charm-decay electrons. Addressed by • e correlation with Muon Telescope Detector at STAR from ccbar: • S/B=2 (Meu>3 GeV/c2 and pT(e)<2 GeV/c) • S/B=8 with electron pairing and tofassociation • Accurate D meson measurements

  49. Summary • Precision measurements of J/ψ will continue to be one of the most important tasks in the field • Precision measurements of other heavy flavor probes are a necessary condition for a complete understanding of the interaction between heavy quarks and the Medium. • STAR HFT and MTD upgrades together with existing subsystems and RHIC II luminosities will provide us with the unprecedented opportunity to accomplish these tasks. • The accomplishment of these tasks will allow us to better understand the medium properties, which may leads to new discoveries.

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