1. Sijin QIAN On behalf of Peking University CMS Group 钱思进 （北京大学 物理学院） 第十届全国粒子物理学术会议，南京， 27-4-2008 To Measure Production Cross-section and Polarization of Heavy Quarkonium in CMS on LHC 大型强子对撞机上 CMS 实验对 重夸克偶素的产生截面和极化的测量

2. 2 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Outline Introduction to Peking University (PKU) CMS group Motivation to study the heavy quarkonium production and polarization Color-Octet quarkonium generation Muon and di-muon reconstruction Production cross-section measurement Polarization extraction HLT trigger J/  cross-section plots for 10 or 5pb -1 Summary and prospective

3. 3 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 PKU CMS group 4 Professors: (1) Yanlin YE, (2) Yong BAN, (3) Yajun MAO and (4) Sijin QIAN 1 Lecturer: Siguang WANG 6 Graduate Students: Haiyun TENG [2], Bo ZHU [3], Zongchang YANG [4], Lie LIU [4], Shuang GUO [4], Zhen HU [4] Some engineers, technicians and undergraduate students. Hardware contribution to CMS: 144 (i.e. 1/3 of all) Endcap PRCs in CMS Muon system  see Prof. BAN’s presentation in this afternoon Physics analysis topics planned: (a) Heavy quarkonium and NRQCD  this report (b) Polarization of top quark and parity violation (c) Large missing pT of charged leptons and invisible Higgs

4. 4 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Heavy Quarkonium Study Suggested by Prof. Guangda ZHAO in 2003 Have made the presentations in various CMS physics analysis meetings at CERN for 31 times since 2005/7 (21 times since 2007/3) Have published (or submitted) two CMS relevant Notes: –CMS Note 2007/017 "J/    Reconstruction in CMS" –CMS Analysis Note AN-2007/023 "Measurement of Heavy Quarkonium Production and Polarization in CMS"

5. 5 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Two CMS Publications

6. 6 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Prompt charmonium production Bottomonium production black dot: CDF experiment dashed line: color-singlet solid line : NRQCD COM fit J/  ： PRL, 79 (1997) 572  ： PRL, 88 (2001) 161802 Two motivations to study the heavy quarkonium production and polarization: 1.Measure the cross section of J/psi at 14TeV. CSM (Color Singlet Model) : LO, NLO, NNLO COM (Color Octet Mechanism) : NRQCD The measured cross section in CDF experiment is much larger than the calculation from CSM, while COM can fit the curve. Motivation (1)

7. 7 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化  =+1: transversely polarized  =  1: longitudinally polarized CDF run 1    J/  direction in lab frame   direction in J/  rest frame PRL, 87 (2001) 022002 2. The polarization puzzle. COM also predicts an increasingly transverse polarizations as pT increases. But both RUN I and II both didn’t show such a trend. arXiv:0704.0638v1 (2007) Motivation (2) NRQCD prediction CDF run 2

8. 8 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 PRL, 87 (2001) 022002 New theoretical development at NNLO From Aafke Kraan of Pisa

9. 9 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Event generation (1) Use PYTHIA6.4.09 and tune the parameters to fit with CDF data CDF RUN I CDF RUN II Use the values of NRQCD matrix elements in hep-ph/0106120 Use the DWT tunings in most of the CMS production

10. 10 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Event generation (2) Prediction of the differential cross-section of prompt J/  and B decayed J/  at LHC, 14TeV Prompt J/  : Use the tuned parameters and increase energy to 14TeV B decayed J/  : MSEL=1, QCD processes

11. 11 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 MC simulation to fit Upsilon differential cross section at CDF P T (GeV/c) NRQCD Parameters: –PARP(146)=9.28 –PARP(147)=0.15 –PARP(148)=0.02 –PARP(149)=0.02 –PARP(150)=0.09 Reweight routine was performed

12. 12 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Muon reconstruction Bottom: Muon acceptance Right: Muon reconstruction efficiency vs p T and  Eff vs p T Eff vs  We required 2 muon’s p T >3GeV at generator level.

13. 13 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 J/  Mass Fit To determine the number of J/  candidates, in each J/  pT bin, the di- muon invariant mass distributions are fitted with a signal peak and a linear background. Mass distribution fit with linear background and signal peak of a simple Gaussian (left) or a double Gaussian (right).

14. 14 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Dimuon (J/  ) reconstruction Bottom: Dimuon pT and  distribution Right: Dimuon reconstruction efficiency vs pT and  Eff vs p T Eff vs 

15. 15 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Performance of Upsilon reconstruction in CMS Single Gaussian fit Double Gaussian fit

16. 16 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Dimuon (Upsilon) reconstruction efficiency vs. pT and 

17. 17 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Measurement of Cross-section 1. : the integral luminosity 2.  P T : the size of the pT bin. 3. N sig : the number of reconstructed J/  signals 4. A, A’ : the acceptance and relative acceptance 5.  trigger : trigger efficiency 6.  offreco : off-line reconstruction efficiency The inclusive J/  cross-section is calculated by

18. 18 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Acceptances and efficiencies To calculate the acceptances, we may combine the –Geometrical acceptance, –MC trigger efficiency and –MC offline reconstruction efficiency as The trigger and offline efficiencies from data are considered as a correction factor.

19. 19 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Muon efficiency Muon efficiencies can be measured from data by Tag&probe method. It strongly depends on the cuts (  p T &  R). Tag&probe can be used both on MC events or real data. Thus the correction factor is: is ideal to be 1.

20. 20 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 J/  Efficiencies The offline J/psi reconstruction efficiency is a function of J/  ’s pT, eta and polarization angle. Here: P  (p T,  ) is the probability density function of muons from J/  decays, can be extracted by Monte Carlo.  (p T,  ) is the correction factor of muon offline reconstruction efficiency.

21. 21 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B fraction (1) The B fraction can be extracted by fitting the pseudo-proper decay length distribution of the J/  : is the J/psi transverse proper decay length  1.Prompt J/  starts to decay immediately. 2.B-hadrons have some long lifetimes.

22. 22 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B fraction (2) Constrain the two Gaussian with the same mean value

23. 23 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B fraction (3) mean_core = mean_tail PromptNonPromptCombined fra_tail9.44831e-024.18656e-021.18763e-01 mean_core8.05345e-06-8.32907e-04-3.10517e-05 mean_tail=mean_core sigma_core3.72622e-033.89145e-033.46209e-03 sigma_tail2.55135e-025.44455e-022.21717e-02 frac_Bdecay2.97188e-01 tau4.17653e-024.14621e-02

24. 24 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B fraction (4) B fraction from fit comparing to the MC truth.

25. 25 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Polarization measurement CDF used a method called Template fit – to fit the data to a weighted sum of two MC templates: - transverse polarization template - longitudinal polarization template    J/  direction in lab frame   direction in J/  rest frame  = -1 generation  = +1 generation  =-1 reco template  =+1reco template

26. 26 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Methods to extract polarization parameter  1.Template fit –Find the cos(  ) distribution of signal events –Produce templates by weighting MC events with  and  –Fit the data to the combinations of longitudinally and transversely polarized MC templates 2.Iterative fit 3.ANN (Artificial Neural Network)

27. 27 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Method (2): Iterative method Iterative method is almost the same as the previous one. The difference is that we input a normalization parameter at the beginning by: Then fit a value  1, and use  1 to calculate F norm (  =  1 ). And then use F norm (  =  1 ) as input to fit  2 …etc. The fitting result converges quickly, and becomes stable after tens of step. transversely polarized longitudinally polarized

28. 28 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Method (3): A rtificial N eural N etwork cos  distributions can be normalized to be the pdfs (probability density function). ANN (Artificial Neural Network) can learn these pdfs and fit the data distribution function. Here only the shape of cos  distribution is used.

29. 29 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Compare the 3 methods 1.These three methods all describe the right trend in transverse and longitudinal samples. 2.The first two methods need a precise measurement of the J/psi efficiencies, while ANN doesn’t depends on the efficiencies. 3.ANN also has a disadvantage that it needs a large amount of events both in signals and templates.

30. 30 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 HLT trigger

31. 31 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 HLT J/  (or Upsilon) trigger L2 muon reconstru ction L2 J/  Filter L3 muon reconstru ction L3 J/  Filter L1_DoubleMu3: true MaxEta = 2.5 MinPt = 0 MinQuality = -1 MinN = 2 MaxEta = 2.5 MinNhits = 0 MaxDr = 100. MaxDz = 9999. ChargeOpt = 0 MinPt = 3. MinInvMass = 1.0 MaxInvMass = 5.0 NSigmaPt = 0. MaxEta = 2.5 MinNhits = 0 MaxDr = 0.02 MaxDz = 9999. ChargeOpt = 0 MinPt = 3. MinInvMass = 2.8 MaxInvMass = 3.4 NSigmaPt = 0. L1  Filte r

32. 32 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 J/psi L2 and L3 dimuons L2 dimuons L3 dimuons These windows should be large enough since sideband events are very important in physics analysis 1 5 2.8 3.4

33. 33 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Upsilon mass windows for L2 and L3

34. 34 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 L1 and HLT efficiencies L1 and HLT trigger efficiencies of different HLT paths. The L1/HLT efficiency is that the efficiency of an offline reconstructed and selected J/psi passes L1/HLT trigger.

35. 35 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Trigger efficiency from data The dimuon trigger efficiencies can be expressed as The L1/L2/L3 muon trigger efficiency is defined as the probability of an offline reconstructed muon to pass the L1/L2/L3 trigger criterias. corresponds to the dimuon correlation effects which is assumed to be 1. Then we use tag&probe method on the single muon trigger efficiencies.

36. 36 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Statistics At an integral luminosity of 10pb -1, 100pb -1 or 1000pb -1, with HLT J/  or Upsilon triggers, we shall have: With 40pb -1, CMS may have 572K prompt J/  which are as twice many as CDF had. With 70pb -1, CMS may have 79K prompt Y(1s) which are about an order of magnitude higher than CDF had. 10pb -1 100pb -1 1000pb -1 CDF Statistics J/psi Prompt J/psi signals143K1.43M14.3M300K (40pb -1 ) Nom-prompt signals74K740K7.4M- Backgrounds33K330K3.3M- Y(1s) Signals11.3K113K1.13M6K (70pb -1 ) Backgrounds10.4K104K1.04M-

37. 37 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Misalignment J/psi mass distribution in different misalignment scenarios. The efficiency is much lower at 10pb-1 misalignment. The resolution improves with long term alignment. scenariosMass resolution 10pb-1 34.4MeV 100pb-1 31.2MeV Long term 30.9MeV

38. 38 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 For 10 pb -1 data In 10pb-1, the invariant mass peak of two global muons pass the HLT trigger and offline selection: dimuon pT>3GeV/c |eta|<2.4

39. 39 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 J/  Differential Cross Section For 5pb -1 Only statistic errors

40. 40 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B-physics group summary in CMS physics plenary a week ago (1) Among total 21 pages, 6 pages are related with PKU

41. 41 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B-physics group summary in CMS physics plenary a week ago (2) P. 5

42. 42 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B-physics group summary in CMS physics plenary a week ago (3) P.11

43. 43 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B-physics group summary in CMS physics plenary a week ago (4) P.12

44. 44 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B-physics group summary in CMS physics plenary a week ago (6) P.13

45. 45 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B-physics group summary in CMS physics plenary a week ago (5) P.14

46. 46 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 B-physics group summary in CMS physics plenary a week ago (6) P.21 PKU’s work

47. 47 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Summary/Prespective The solid ways to measure the heavy quarkonium production and polarization have been developed in PKU. Our work has been well recognized and encouraged by CMS; hopefully it can lead to one of the first CMS physics publications after LHC’s proton collision. With more CMS data to come in next couple of years, we hope that this work can provide more clues for theorists to verify various models in NRQCD. To make more precise measurement, we have to understand the detector and CMSSW performances better; therefore, more hard works and challenges ahead us, we are delight to have this unusual opportunity and shall do our best for it.

48. 48 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Thank you !

49. 49 第十届全国粒子物理学术会议，南京， 27-4-2008 钱思进 CMS 重夸克偶素的产生截面和极化 Backup