1. 1 Zhangbu Xu (for the STAR Collaboration) Brookhaven National Laboratory High-p T J/ at  STAR Outline: Introduction J/ yields and suppression J/ -h correlation Outlook (+MTD)

2. Quarkonia in sQGP Color screening effect 1) Recombination 2) Gluon energy loss 3) Heavy quark energy loss 3) Decay feed-down (comover, cold matter effect) at (hadronic phase, initial stage) 2 1) T. Matsui and H. Satz, Phys. Lett. B178, 416 (1986) 2) R. L. Thews and M. L. Mangano, Phys. Rev. C73, 014904 (2006) 3) M. B. Johnson et al., Phys. Rev. Lett. 86, 4483 (2001) and R. Baier et al., Ann. Rev. Nucl. Part. Sci. 50, 37 (2000) How do the quarkonium behave in the presence of sQGP?

3. High p T J/  in heavy ion collisions 3 J/  H. Satz, Nucl. Phys. A (783):249-260(2007) J/  suppression at low p T could be from suppressed excited states (  ’,  c ) F. Karsch, D. Kharzeev and H. Satz, PLB 637, 75 (2006) High p T direct J/  suppression  related to hot wind dissociation? Hot wind dissociation H. Liu, K. Rajagopal and U.A. Wiedemann PRL 98, 182301(2007) and hep-ph/0607062 2-component approach Predicted decrease R AA X. Zhao and R. Rapp, hep-ph/07122407 Color singlet model predicted an increase R AA (formed outside of medium) K. Farsch and R. Petronzio, PLB 193(1987), 105 J.P. Blaizot and J.Y. Ollitrault, PLB 199(1987),499 T. Gunji, QM08

4. The STAR Detector Zebo Tang, USTC/BNL4 MagnetCoilsCentralTriggerBarrel(CTB)ZCalTimeProjectionChamber(TPC) Year 2000 Barrel EM Cal (BEMC) Silicon Vertex Tracker (SVT) Silicon Strip Detector (SSD) FTPC Endcap EM Cal FPD TOFp, TOFr PMD Year 2001+ Large acceptance: 2  coverage at mid-rapidity Future upgrade: Time of Flight, DAQ1000, Heavy Flavor Tracker, Muon Telescope Detector

5. 5 Low p T J/  in p+p at 200 GeV J/  trigger 0 < p T < 5.5 GeV/c MC describes position and width p+p 200 GeV STAR has J/  capabilities at low p T Mass and width consistent with MC simulation, low mass tail from electron bremsstrahlung Integrated p+p luminosity at 200 GeV: 0.4 (pb) -1

6. High p T J/  in p+p at 200 GeV 6 J/  p T EMC+TPC electrons:  1, p T >2.5 GeV/c TPC only electrons:  1, p T >1.2 GeV/c EMC+TPC electrons:  1, p T >4.0 GeV/c TPC only electrons:  1, p T >1.2 GeV/c No background at p T >5GeV/c Reach higher p T (~14GeV/c) p+p 2005 p+p 2006 (S+B)/B: 24/2 (S+B)/B: 54/14 EMC trigger 3 pb -1 11 pb -1

7. 7 J/  spectra in p+p at 200 GeV Significantly extend p T range of previous measurements in p+p at RHIC to 14 GeV/c Agreement of charm measurements between STAR and PHENIX Consistent with Color Evaporation calculations (R. Vogt, Private communication)

8. J/  in Cu+Cu Signal with good S/B ratio p T range overlaps with p+p data Luminosity: 0.9 nb -1

9. Nuclear modification factor R AA 9 Double the p T range to 10GeV/c Consistent with no suppression at high p T : R AA (p T >5 GeV/c) = 0.9±0.2 2  above low-p T data Indicates R AA increase from low p T to high p T Doesn’t agree with AdS/CFT prediction Formed out of medium? Affect by heavy quark/gluon energy loss Decay from other particles? 2-component Approach predicted slightly increase R AA after more consideration X. Zhao, WWND2008

10. R AA Comparison to NA60 10 RHIC: Cu+Cu, consistent with no suppression at p T > 5 GeV SPS: In+In,, consistent with no suppression at p T > 1.8 GeV Cronin pA  pp Thermal fit R. Arnaldi (NA60) QM08 Important to understand production mechanism 

11. Quarkonium production mechanism Color singlet model (CSM) 1)  pQCD Color octet model (COM) 2)  NRQCD Color evaporation model (CEM) 3) … Gluon fusion Heavy quark fragmentation 4) Gluon fragmentation 5) Decay feed-down … 11 1) R. Baier et al., PLB 102, 364 (1981) 2) M. Kramer, Progress in Particle and Nuclear Physics 47, 141 (2001) 3) H. Fritzsch, PLB 67, 217 (1977) 4) Cong-Feng Qiao, hep-ph/0202227 5) K. Hagiwara et al., hep-ph/0705.0803 NRQCD What’s the production mechanism at RHIC energy?

12. CSM with k t -factorization 12 CSM can also describe the data with some improvement like the k t -factorization approach PHENIX, PRL 92, 05180 (2004) S.P. Baranov and A. Szczurek arXiv:0710.1792 d  /dp T [nb/(GeV/c)] p T (GeV/c) Color singlet LHC 14 TeV Tevatron 1.96 TeV LO NLO PRL98, 252002(2007)

13. x T scaling 13 n is related to the number of point-like constituents taking an active role in the interaction n=8: diquark scattering n=4: QED-like scattering x T scaling:  and proton: n=6.5±0.8 PLB 637, 161(2006) J/  : n=5.6±0.2 J/  production: closer to 2  2 scattering

14. (B  J/  )/(inclusive J/  ) 14 1)Generated B spectrum is from pQCD M. Cacciari, P. Nason and R. Vogt PRL 95(2005),122001 2)Decay B  J/ , kinematics and branch ratio are from CLEO measurements CLEO collaboration PRL 89(2002),282001 B  J/  contributes significantly to the inclusive J/  yields at high p T (>5 GeV/c) Assuming B production from pQCD (no experimental B spectra at RHIC yet) Can be used to constrain B production

15. More J/  production puzzles 15 Belle, PRL 89, 142001(2002) e + e -, 10.6 GeV 0.82 ±0.15 ± 0.14 from new analysis. While CEM predict 0.049 D. Kang, et al., PRD 71, 094019 and hep-ph/0412381 T. Uglov, EPS 2003 What happens?: In p+p collisions; At higher energy (200 GeV) (e + e -  J/  +cc)/(e + e -  J/  + X) = 0.59 +0.15 -0.13 ±0.12 NRQCD predict ~0.1 K. Liu and Z. He, PRD 68, 031501 (2003) B.L. Loffe and D.E. Kharzeev PRD 69, 014016 (2004)

16. J/  -hadron correlation RBRC Workshop, BNL, April 23-25, 2008 16 (S+B)/B: 54/14 Heavy quark fragmentation Near side correlation Good S/B ratio makes this measurement possible

17. Disentangle contributions via Correlations 17 J/  -hadron correlation can also shed light on different source contribution to J/  production May be used to distinct CSM and COM 1) no near side correlation 2) strong near side correlation PLB 200, 380(1988) and PLB 256,112(1991)

18. J/  hadron correlation in p+p 18 PRL 95,152301(2005) h-h correlation No significant near side J/  -hadron azimuthal angle correlation Constrain B meson’s contribution to J/  yield Hints of CSM?

19. Yields in near/away side 19 Associated hadron spectra with leading J/  : Away side: Consistent with leading charged hadron correlation measurement (h-h)  away-side from gluon or light quark fragmentation Near side: Consistent with no associated hadron production B  J/  not a dominant contributor to inclusive J/  constrain J/  production mechanism

20. Constrain Bottom yields pQCD predicts significant B  J/ Correlations shows low B contribution can used to further constrain B yields PYTHIA productions all show strong near-side correlation  higher order production mechanism?

21. 21 Future dramatic improvement of J /  at low p T EMC+TOF (large acceptance): J /  production Different states predicted to melt at different T in color medium Charmonia(J/  ), bottonia (  ) Quarkonium dissociation temperatures – Digal, Karsch, Satz pT (e)>1.5 GeV/c PHENIX Acceptance: ||<0.35,=2*/2 STAR TOF-Upgrade Acceptance: ||<0.9,=2* J /  yields from 10 9 minbias Au+Au events: 43.8x10 -9 /0.040x10 9 *292*0.5*1.8*0.5= 144,000  0.3% v 2 error  J/  pp N N bin  y R AA dE/dx after TOF cut

22. High luminosity for Υ & high-p T J/  RHIC II + DAQ1000: Time-Of-Flight: Electron identification Enhance statistics

23. Longer term: Quarkonia in STAR Heavy Flavor Tracker: Muon Telescope Detector:   e + e - rejection Topologically reconstruct J/ from B decay Rejection power: ~16  +  - simulation Muon identification

24. 24 A novel and compact muon telescope detector for QCDLab A large area of muon telescope detector (MTD) at mid-rapidity, allows for the detection of di-muon pairs from QGP thermal radiation, quarkonia, light vector mesons, possible correlations of quarks and gluons as resonances in QGP, and Drell-Yan production single muons from their semi- leptonic decays of heavy flavor hadrons advantages over electrons: no  conversion, much less Dalitz decay contribution, less affected by radiative losses in the detector materials +- BNL LDRD 07—007 project

25. 25 Concept of Design A pseudo detector with scintillator covering the whole iron bars and left the gaps in-between uncovered. 1.muon efficiency: 35-45%, pion efficiency: 0.5-1% 2.muon-to-pion enhancement factor: 50-100 3.muon-to-hadron enhancement factor: 100-1000 including track matching, tof and dE/dx 4.dimuon trigger enhancement factor from online trigger: 10-50 Detection efficiency p T (GeV) pion muon  This together with DAQ1000 will greatly enhance our capability of J/ and other dilepton program in RHIC II and future QCD Lab

26. Cosmic Ray Results: Long-Strip Multi-gap Resistive Plate Chamber Technology Long MRPC Technology with double-end readout HV:  6.3 KV gas mixture: 95% Freon + 5% isobutane time resolution: ~60 ps spatial resolution: ~1cm efficiency: >95% 950 mm 256 mm 25 mm Y. Sun et al., nucl-ex/0805.2459

27. 27 HV: 6.3 KV gas mixture: 95% Freon + 5% isobutane time resolution: ~60-70 ps spatial resolution: ~0.6-1cm efficiency: >95% consistent with cosmic test results Tsinghua module as trigger Scintillator as trigger USTC Y. Sun et al., nucl-ex/0805.2459 Fermi Lab Beam Test Results (T963 May 2-15 2007)

28. 28 STAR-MTD in Year 2007 iron bars as hadron absorber; two scintillator trays as our trigger 403 cm away from TPC center, ||<0.25 gas: 95% Freon and 5% iso-butane; HV: 6.3 KV MTD Triggered events: 380 K Au+Au events were taken 1.7 M d+Au and 700 K p+p events taken in run 8

29. 29 Performance at STAR MTD hits: matched with real high p T tracks z distribution has two components: narrow (muon) and broad (hadron) ones spatial resolution (narrow Gaussian) is ~10 cm at p T >2 GeV; hadron rejection: 200-300 time resolution: 300 ps  Improve our electronics with full scale detector STAR Preliminary p T >2 GeV/c STAR Preliminary

30. 30 Compared to Simulation from data: p T >2 GeV/c, (z) of muon: ~10 cm from simulation: p T =2.5 GeV/c, (z) of muon: ~9 cm Data and simulation show consistent results p T (GeV/c) z (cm) muonspions muons

31. Are they prompt muons? MTD hit distribution dE/dx (    Time of flight (  ) Ks   - Kaon dE/dx n  <-1 n  >0 p T >2 GeV/c STAR Preliminary p T >2 GeV/c

32. Nu Xu RHIC Science and Technology Review, July 7-9, 2008 32/30 A complete MTD at STARMRPC ToF barrel Ready for run 10 RPSD PMD FPD FMSFMS EMC barrel EMC End Cap DAQ1000 Ready for run 9 FGT Complete Ongoing MTD R&D HFT TPC To install another tray with TOF electronics in run9 Collaborators for a proposal of full scale detector: 56.6% in azimuth, |eta|<0.88; current tray design: 360 modules, 2160 read-out strips, 4320 channels. (TOF: 23 K readout channels).

33. Summary (J/  ) 33 J/  spectra in 200 GeV p+p collisions at STAR 1.Extend the p T range up to ~14 GeV/c 2.Spectra can be described by CEM and CSM. 3.High p T J/  follows x T scaling with n=5.6 4.Spectra at high p T can be used to constrain B production J  hadron azimuthal correlation in p+p 1.no significant near side correlation Expect strong near-side correlation from B  J/  +X Can be used to constrain J/  production mechanism 2.Away-side spectra consistent with h-h correlation indicates gluon or light quark fragmentation J/  R AA from 200 GeV Cu+Cu collisions at STAR 1.Extend R AA from p T = 5 GeV/c to 10 GeV/c 2.Indication of R AA increasing at high p T

34. Future 34 J/  results from Run 7 Au+Au, data is still under production Upsilon R AA Run 8 (d+Au) just finished, Cold Nuclear Modification Run9—10, Au+Au and p+p runs with TOF and DAQ1000 Longer term: HFT, MTD

35. Backup slides 35

36. 36 Datasets p+p data sample:  1. EMC triggered events in year 2005 E T >3.5 GeV Integrated luminosity: 3 (pb) -1  2. EMC triggered events in year 2006 E T >5.4 GeV Integrated luminosity: 11 (pb) -1 Cu+Cu data sample:  1. EMC triggered events in year 2005 E T >3.75 GeV Integrated luminosity: 0.9 (nb) -1 pp-equivalent: 3 (pb) -1 High-p T J/  p+p data sample: 1. J/ψ triggered events in year 2006 Integrated luminosity: 377 (nb) -1 2. Υ triggered events in year 2006 Integrated luminosity: 9(pb) -1 Au+Au data sample: 1. Υ triggered events in year 2007 Integrated luminosity: 300(μb) -1 pp-equivalent: 12(pb) -1 Triggered data

37. 06/17/2008Lijuan Ruan (UC Davis Collboration Meeting) 37 Muon Identification: dE/dx Effect STAR Preliminary n  <-1 STAR Preliminary n  >0 the narrow Gaussian distribution: dominated by muons STAR Preliminary |z|<20

38. 06/17/2008 Lijuan Ruan (UC Davis Collboration Meeting) 38 How do I know dE/dx is right? dE/dx: by selecting pions from K S daughter nsigmapion for pion: -1.16 (mean), 1.14 (sigma)

39. 06/17/2008Lijuan Ruan (UC Davis Collboration Meeting) 39 the narrow Gaussian distribution: dominated by muons Muon Identification: Cut on High Velocity STAR Preliminary 1/ trackhits - 1/ rawhits >0 n  >0 STAR Preliminary

40. 06/17/2008 Lijuan Ruan (UC Davis Collboration Meeting) 40 Muons from Pion Decay? Primary tracks Other sector: 4.65e05 p T > 2 GeV/c tracks, 2236 K S reconstructed. MTD matched tracks: 2619 tracks, 3.35.8 K S obsverd. If all muons are from pion decay, 13 K S expected. Consistent with no secondary muon contribution to narrow Gaussian from pion decay.

41. 06/17/2008 Lijuan Ruan (UC Davis Collboration Meeting) 41 Muons from Kaon Decay? Left plot: no dE/dx cut Right plot: -5<n  <-2.6, Pion(-1.2) Muon(-0.6) Kaon(-2.6), then Muon: 4.8%, Kaon: 48%. I observed 99-1624*4.8%=22 muons. Muons from kaon decay: 22/48%/1624=2.8%. Secondary muons contribution to narrow Gaussian is small from kaon decay. p T >2 GeV/c STAR Preliminary