1 / 46

Quarkonia Measurements by the CMS Experiment in pp and PbPb Collisions

Quarkonia Measurements by the CMS Experiment in pp and PbPb Collisions . Catherine Silvestre Tello for the CMS Collaboration. Quarkonia in Heavy Ion Collisions. Good candidates to probe the QGP in HIC

ginger
Télécharger la présentation

Quarkonia Measurements by the CMS Experiment in pp and PbPb Collisions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Quarkonia Measurements by the CMS Experiment in pp and PbPb Collisions Catherine Silvestre Tello for the CMS Collaboration

  2. Quarkonia in Heavy Ion Collisions • Good candidates to probe the QGP in HIC • Large masses and (dominantly) produced at the early stage of the collision via hard-scattering of gluons • Strongly bound resonances → decreasing binding energy • The start : quarkonia should melt in the QGP • T. Matsui & H. Satz PLB178, 416 (1986) • Color Screening catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  3. A Complex Production • Production mechanism not completely understood • Many effects altering production in nuclear reactions • In pA, cold nuclear matter (CNM) effects • Extensively studied at the SPS and RHIC • But different at the LHC ? • In AA, hot medium effects J-P Lansberg (Tues) The NNLO* is not a complete NNLO → possibility of (large) uncanceled logs ! If NNLO* ≈ NLO, problem with polarization catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  4. RHIC J/y Suppression Puzzles • No increase of the suppression with local density RAA (|y|<0.35) > RAA (1.2<|y|<2.2) • Similar suppression at SPS and RHIC energies RAA (RHIC, |y|<0.35) ≈ RAA (SPS) • Possible ingredients • Suppression (gluon diss.) • Sequential melting • Gluon saturation / shadowing • Regeneration • Some combination of all J/y catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  5. SOLENOID 3.8 T B-field Cathode Strip Chambers (CSC) Resistive Plate Chambers (RPC) Drift Tube (DT) Resistive Plate Chambers (RPC) Compact Muon Solenoid MUON ENDCAPS TRACKER Add castor MUON BARREL Silicon Strips Pixels catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  6. Quarkonia in CMS • Precision quarkonia physics • High statistics run pp√s=7 TeV Lint=40 pb-1 • Nuclear modification factor • PbPb √sNN=2.76 TeVLint=7.28 mb-1 • pp√s=2.76 TeVLint=225 nb-1 • Similar hard probes statistics • Good reference • Same reconstruction algorithm PbPb catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  7. pp√s=7 TeV catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  8. Di-muons from CMS pp √s=7 TeV catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  9. Inclusive J/y pp √s=7 TeV Lint=40 pb-1 |y|<0.5 J/y |yJ/y|<0.5 s=20 MeV/c2 y’ N J/y (120.5 ± 0.8)⋅103 • b-quark physics • Quarkonia physics catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  10. B → J/y pp √s=7 TeV • Reconstruct µ+µ− vertex • Simultaneous fit • Invariant mass • Pseudo-proper decay length EPJC 71:1515 (2011) Torsten Dahms (Tues. 15h) Mihee Jo (poster 458) FLASH TALK ! 1.6<|y|<2.4 catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  11. J/y Cross Section pp √s=7 TeV PROMPT NON PROMPT • Prompt J/y production not well reproduced • Models describe non-prompt J/y production better EPJC 71:1515 (2011) catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  12.  States pp √s=7 TeV • Very good dimuon mass resolution → separation of the 3  states |hm| < 2.4 s= 100 MeV/c2 |hm| < 1 s = 67 MeV/c2 1S 1S 2S 2S 3S 3S catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  13.  Cross Section pp √s=7 TeV • Pythia (LO / CSM+COM) • Reasonable agreement in shape • But not in normalization (overestimated by about a factor 2) (1S) arXiv : 1012.5545 accepted by PRD catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  14. Quarkonia in pp • Summary of the 7 TeV run • Differential charmonia and bottomonia • Constrain production mechanisms • In progress • cc, y’, quarkonium polarization • Heavy ion reference run √s=2.76 TeV pTJ/y> 6.5 GeV/c 101±12  s = 36 MeV/c2 1026 ± 35 J/y pT m > 4 GeV/c catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  15. PbPb collisions catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  16. Di-muons by CMS in PbPb Jorge Robles Thursday 15h00 Zhen Hu Monday 19h10 Torsten Dahms Tuesday 15h00 PAS CMS HIN-10-006 catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  17. Inclusive J/y PbPb √sNN=2.76 TeV Similar resolution as in pp 734 ± 54 J/y Torsten Dahms (Tues. 15h) catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  18. First Non-Prompt J/y PbPb √sNN=2.76 TeV 90 ± 13 B → J/y b-quark physics pTJ/y> 6.5 GeV/c Torsten Dahms (Tues. 15h) Mihee Jo (poster 458) FLASH TALK ! catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  19. Corrections PbPb √sNN=2.76 TeV Acceptance from MC Efficiency : centrality dependence ~17% • Efficiency from MC, checked with data :14% systematics Hyunchul Kim (poster 460, 67) Dongho Moon (poster 459, 66) catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  20. Prompt J/y RAA vs. pT PbPb √sNN=2.76 TeV Minimum bias RAA = 0.30 ± 0.02 ± 0.02 PAS CMS HIN-10-006 pTJ/y> 6.5 GeV/c catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  21. J/y RAA vs. pT : Comparison High pTJ/y’s tendency to survive at RHIC (and SPS) is not seen at the LHC CMS pTJ/y> 6.5 GeV/c STAR pTJ/y< 8 GeV/c PHENIX lower pT catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  22. Prompt J/y RAA vs. y PbPb √sNN=2.76 TeV • Less suppression at forward rapidity for high pT • Anti-shadowing ? • CMS@pT=10 up to x2~0.02 (x1~5.10-4) CMS Q2=10 GeV2 EPS09 NLO nDSg NLO catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  23. J/y RAA vs. y : Comparison CMS for pT>3 GeV/c 1.6<y<2.4 RAA= 0.39±0.06±0.03 ALICE Low pTJ/y RAA= 0.49±0.03±0.11 • CMS : opposite trend than PHENIX but different pT • Increasing RAA going towards ALICE y range CMS pTJ/y> 6.5 GeV/c PHENIX lower pTJ/y P. Pillot (Tues.) ALICE CMS M. Wysocki (Poster) Q2=10 GeV2 EPS09 NLO nDSg NLO • CMS@pT=10 up to x2~0.02 (x1~5.10-4) • ALICE@pT=0 up to x2~0.06 (x1~2.10-5) • Watch out for anti-shadowing : catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  24. Prompt J/y RAA PbPb √sNN=2.76 TeV Central 0-10% RAA= 0.20 ± 0.03 ± 0.01 Peripheral 50-100% RAA= 0.59 ± 0.12 ± 0.10 CMS pTJ/y> 6.5 GeV/c Factor 5 suppression catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  25. J/y RAA vs. Npart Comparison STAR √s=200 GeV, J/y 5 < pT< 8 GeV/c Stronger suppression seen in CMS than at STAR 40-80% Compatible with ATLAS Rcp= 0.5 ± 0.2 CMS pTJ/y> 6.5 GeV/c STAR 5<pTJ/y<8 GeV/c Phys.Lett.B697: 294-312,2011 P. Steinberg (Mon.) R. Sandstrom (Thur.) Z. Tang (Mon.) catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  26. (parenthesis from quarkonia : b-quark energy loss) catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  27. First B → J/y RAA PbPb √sNN=2.76 TeV Minimum bias RAA = 0.37 ± 0.07 ± 0.03 Central 0-20% RAA= 0.36 ± 0.08 ± 0.03 pT J/y > 6.5 GeV/c b quark energy loss ? 20-100% catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  28. High pT Suppression PbPb √sNN=2.76 TeV B→J/y at the pT of the J/y Same level of suppression as hadrons Yen-Jie Lee(Wed. 9h) catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  29. Back to quarkonia :bottomonia catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  30.  States PbPb √sNN=2.76 TeV 86 ± 12 (1S) pT m > 4 GeV/c Zhen Hu (Mon. 19h10) catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  31. (1S) RAA PbPb √sNN=2.76 TeV • Minimum bias RAA= 0.62 ± 0.11 ± 0.10 • High pT not as suppressed ? • Need more statistics catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  32. (1S) RAA PbPb √sNN=2.76 TeV • Comparison with STAR • CMS (1S) RAA(0-100) = 0.62 ± 0.11 ± 0.10 • STAR (1+2+3S) RAA(0-60) = 0.56 ± 0.11 +0.02-0.10 R. Reed (poster) catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  33. (2S+3S) Suppression PbPb √sNN=2.76 TeV • (2S+3S) production relative to (1S) in pp and PbPb • Compare pp and PbPb through a simultaneous fit pp PbPb pT m > 4 GeV/c arXiv : 1105.4894 Submitted to PRL catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  34. (2S+3S) Suppression PbPb √sNN=2.76 TeV • Pros of a double ratio • Acceptance cancels • Efficiency cancels • Potential differences • Remaining systematics 9%, from line shapes PbPb arXiv : 1105.4894 Submitted to PRL Hypothesis: no suppression ⇒ p-value 1% Significance of the suppression 2.4 s catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  35.  Suppression PbPb √sNN=2.76 TeV • Large fraction of (1S) come from excited states • Feed down ~50% from χb for pT() >8 GeV/c • 40% suppression of (1S) • Relative suppression of (2S+3S) vs. (1S) • Observation consistent with melting of the excited states only ? • What about cold nuclear matter effects ? • Smaller σabs than at lower energy and for J/y (smaller size) • Shadowing cancelling in the (2S+3S)/(1S) ratio • pA run ? CDF: PRL84 (2000) 2094 R. Vogt, hep-ph/1003.3497 catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011 Make the plots vsNpart upsilon 1S CMS and inclusive Star

  36. Quarkonia Production with CMS • Firstnon-prompt J/y in HI • b-quark energy loss • Prompt J/y significantly suppressed • (2S)+(3S) excited states suppressed • Consistent with 40% (1S) suppression  no pT cut pTJ/y>6.5 GeV/c PAS CMS HIN-10-006 arXiv : 1105.4894 Submitted to PRL Sequential melting accessible with CMS resolution catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  37. Backup catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  38. →e+e- @ RHIC • PHENIX • Au+Au collisions • High mass correlated di-electrons are suppressed • STAR • Au+Au collisions 0-60% • 93 (1,2,3S) Nucl.Phys.A855:440-443,2011 arXiv:0907.4787 catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  39. Pseudo-proper decay length catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  40. Quarkonia Acceptance catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  41. B → J/y Fraction in PbPb and pp catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  42. B → J/y Fraction pp √s=7 TeV arxiv 1104.3038 EPJC 71:1515 (2011) catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  43. Range of predictions • Less suppression • Zhao, Rapp: Due to finite J/ψ formation time, B feed down and Cronin effect • Stronger suppression • « Hot wind » model – cc pair in motion w.r.t. hot medium ⇒ decrease of screening length. _ RAA J/y vs. pT Predictions catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  44. pp Comparison • Same pp reconstruction, including low pT J/y • Agreement of the (2S+3S)/(1S) ratio • pp 2.76 TeV • pp 7 TeV catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

  45. p-value • Generate pseudo-experiments following the null-hypothesis (i.e. no suppression) • Fit pseudo-data samples with nominal fit • Count fraction of occurrences for which the ratio (taken as test statistic) is same or lower than observed: • p-value: 0.9% • 2.4σ (1-sided Gaussian test) Could background fluctuation produce a result as extreme as observed in data? • 0.31 Zhen Hu (Purdue) Quark Matter 2011, Annecy, May 23-29 2011

  46. J/y RAA Comparison PbPb √sNN=2.76 TeV • PHENIX √s=200 GeV, inclusive J/y, pTJ/y<5 GeV/c • SPS, PHENIX, LHC: similar centrality dependence • But different pT, systems and energies CMS pT J/y>6.5 GeV/c catherine.silvestre@cern.ch (LPSC) Quarkonia CMS - Quark Matter 2011

More Related