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Outline

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. Outline. Introduction to Peking University (PKU) CMS group Motivation to study the heavy quarkonium production and polarization Color-Octet quarkonium generation

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Outline

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  1. 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. 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/y cross-section plots for 10 or 5pb-1 • Summary and prospective 钱思进 CMS重夸克偶素的产生截面和极化

  3. 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 钱思进 CMS重夸克偶素的产生截面和极化

  4. 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/ym+m- Reconstruction in CMS" • CMS Analysis Note AN-2007/023 "Measurement of Heavy Quarkonium Production and Polarization in CMS" 钱思进 CMS重夸克偶素的产生截面和极化

  5. Two CMS Publications 钱思进 CMS重夸克偶素的产生截面和极化

  6. Motivation(1) Two motivations to study the heavy quarkonium production and polarization: • 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. Prompt charmonium production Bottomonium production black dot: CDF experiment dashed line: color-singlet solid line : NRQCD COM fit J/Y：PRL, 79 (1997) 572 ： PRL, 88 (2001) 161802 钱思进 CMS重夸克偶素的产生截面和极化

  7. m+ m+ direction in J/Y rest frame q m- J/Y direction in lab frame Motivation(2) 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. NRQCD prediction CDF run 1 PRL, 87 (2001) 022002 CDF run 2 a=+1: transversely polarized a=-1: longitudinally polarized 钱思进 CMS重夸克偶素的产生截面和极化 arXiv:0704.0638v1 (2007)

  8. New theoretical development at NNLO From Aafke Kraan of Pisa PRL, 87 (2001) 022002 钱思进 CMS重夸克偶素的产生截面和极化

  9. 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 钱思进 CMS重夸克偶素的产生截面和极化

  10. Event generation (2) • Prediction of the differential cross-section of prompt J/y and B decayed J/y at LHC, 14TeV Prompt J/y: Use the tuned parameters and increase energy to 14TeV B decayed J/y: MSEL=1, QCD processes 钱思进 CMS重夸克偶素的产生截面和极化

  11. 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 PT(GeV/c) MC simulation to fit Upsilon differential cross section at CDF 钱思进 CMS重夸克偶素的产生截面和极化

  12. Muon reconstruction Bottom: Muon acceptance Right: Muon reconstruction efficiency vs pT and h Eff vs pT We required 2 muon’s pT>3GeV at generator level. Eff vs h 钱思进 CMS重夸克偶素的产生截面和极化

  13. J/y Mass Fit • To determine the number of J/y candidates, in each J/y 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). 钱思进 CMS重夸克偶素的产生截面和极化

  14. Dimuon (J/y) reconstruction Bottom: Dimuon pT and h distribution Right: Dimuon reconstruction efficiency vs pTand h Eff vs pT Eff vs h 钱思进 CMS重夸克偶素的产生截面和极化

  15. Performance of Upsilon reconstruction in CMS Single Gaussian fitDouble Gaussian fit 钱思进 CMS重夸克偶素的产生截面和极化

  16. Dimuon (Upsilon) reconstruction efficiency vs. pT and h 钱思进 CMS重夸克偶素的产生截面和极化

  17. Measurement of Cross-section The inclusive J/y cross-section is calculated by • : the integral luminosity • DPT : the size of the pT bin. • Nsig: the number of reconstructed J/y signals • A, A’ : the acceptance and relative acceptance • etrigger :trigger efficiency • eoffreco :off-line reconstruction efficiency 钱思进 CMS重夸克偶素的产生截面和极化

  18. 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. 钱思进 CMS重夸克偶素的产生截面和极化

  19. Muon efficiency • Muon efficiencies can be measured from data by Tag&probe method. It strongly depends on the cuts (DpT & DR). • Tag&probe can be used both on MC events or real data. Thus the correction factor is: is ideal to be 1. 钱思进 CMS重夸克偶素的产生截面和极化

  20. J/y Efficiencies • The offline J/psi reconstruction efficiency is a function of J/y’s pT, eta and polarization angle. Here: Pm(pT,h)is the probability density function of muons from J/y decays, can be extracted by Monte Carlo. lm(pT,h) is the correction factor of muon offline reconstruction efficiency. 钱思进 CMS重夸克偶素的产生截面和极化

  21. B fraction (1) The B fraction can be extracted by fitting the pseudo-proper decay length distribution of the J/y: is the J/psi transverse proper decay length. • Prompt J/y starts to decay immediately. • B-hadrons have some long lifetimes. 钱思进 CMS重夸克偶素的产生截面和极化

  22. B fraction (2) Constrain the two Gaussian with the same mean value 钱思进 CMS重夸克偶素的产生截面和极化

  23. B fraction (3) 钱思进 CMS重夸克偶素的产生截面和极化

  24. B fraction (4) B fraction from fit comparing to the MC truth. 钱思进 CMS重夸克偶素的产生截面和极化

  25. a = -1 generation a = +1 generation m+ m+ direction in J/Y rest frame q a=-1 reco template a=+1reco template m- J/Y direction in lab frame 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 钱思进 CMS重夸克偶素的产生截面和极化

  26. Methods toextract polarization parameter a • Template fit • Find thecos(q) distribution of signalevents • Produce templates by weighting MC events with a=+1 and a=-1 • Fit the data to the combinations of longitudinally and transversely polarized MC templates • Iterative fit • ANN (Artificial Neural Network) 钱思进 CMS重夸克偶素的产生截面和极化

  27. 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 a1, and use a1 to calculate Fnorm(a=a1). And then use Fnorm(a=a1) as input to fit a2…etc. • The fitting result converges quickly, and becomes stable after tens of step. transversely polarized longitudinally polarized 钱思进 CMS重夸克偶素的产生截面和极化

  28. Method (3): ArtificialNeuralNetwork cosq 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 cosq distribution is used. 钱思进 CMS重夸克偶素的产生截面和极化

  29. Compare the 3 methods • These three methods all describe the right trend in transverse and longitudinal samples. • The first two methods need a precise measurement of the J/psi efficiencies, while ANN doesn’t depends on the efficiencies. • ANN also has a disadvantage that it needs a large amount of events both in signals and templates. 钱思进 CMS重夸克偶素的产生截面和极化

  30. HLT trigger 钱思进 CMS重夸克偶素的产生截面和极化

  31. L2 muon reconstruction L2 J/y Filter L3 muon reconstruction L3 J/y 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. HLT J/y (or Upsilon) trigger L1 mm Filter MaxEta = 2.5 MinNhits = 0 MaxDr = 0.02 MaxDz = 9999. ChargeOpt = 0 MinPt = 3. MinInvMass = 2.8 MaxInvMass = 3.4 NSigmaPt = 0. 钱思进 CMS重夸克偶素的产生截面和极化

  32. J/psi L2 and L3 dimuons L2 dimuons L3 dimuons 15 2.83.4 These windows should be large enough since sideband events are very important in physics analysis 钱思进 CMS重夸克偶素的产生截面和极化

  33. Upsilon mass windows for L2 and L3 钱思进 CMS重夸克偶素的产生截面和极化

  34. 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. 钱思进 CMS重夸克偶素的产生截面和极化

  35. 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. 钱思进 CMS重夸克偶素的产生截面和极化

  36. Statistics • At an integral luminosity of 10pb-1, 100pb-1or 1000pb-1, with HLT J/y or Upsilon triggers, we shall have: • With 40pb-1, CMS may have 572K prompt J/y 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. 钱思进 CMS重夸克偶素的产生截面和极化

  37. 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. 钱思进 CMS重夸克偶素的产生截面和极化

  38. 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 钱思进 CMS重夸克偶素的产生截面和极化

  39. J/y Differential Cross Section • For 5pb-1 Only statistic errors 钱思进 CMS重夸克偶素的产生截面和极化

  40. B-physics group summary in CMS physics plenary a week ago (1) Among total 21 pages, 6 pages are related with PKU 钱思进 CMS重夸克偶素的产生截面和极化

  41. B-physics group summary in CMS physics plenary a week ago (2) P. 5 钱思进 CMS重夸克偶素的产生截面和极化

  42. B-physics group summary in CMS physics plenary a week ago (3) P.11 钱思进 CMS重夸克偶素的产生截面和极化

  43. B-physics group summary in CMS physics plenary a week ago (4) P.12 钱思进 CMS重夸克偶素的产生截面和极化

  44. B-physics group summary in CMS physics plenary a week ago (6) P.13 钱思进 CMS重夸克偶素的产生截面和极化

  45. B-physics group summary in CMS physics plenary a week ago (5) P.14 钱思进 CMS重夸克偶素的产生截面和极化

  46. B-physics group summary in CMS physics plenary a week ago (6) P.21 PKU’s work 钱思进 CMS重夸克偶素的产生截面和极化

  47. 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. 钱思进 CMS重夸克偶素的产生截面和极化

  48. Thank you ! 钱思进 CMS重夸克偶素的产生截面和极化

  49. Backup 钱思进 CMS重夸克偶素的产生截面和极化

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