1. LHCb: Xmas 2010 Tara Shears, On behalf of the LHCb group

2. 1. Introduction 2. Electroweak physics 3. Other work 4. Conclusions Xmas09 and 2010 LHCb overview LHCb kinematic plane Motivation of ewk measurements Introduction Electroweak: Z, W, ratios Other work: other Z channels, exclusive dimuons, A FB Conclusions

3. Data: looking forward to studying high momentum muons with LHCb. W, Z, DY selection studies estimate a statistical precision < 1% with ~100 pb -1 of data (2010). Systematic errors dominated by luminosity uncertainty. Systematic errors for low mass DY need to be studied. Exclusive J/psi have similar yield. Plan: by end 2010 First paper on W, Z production Work towards paper on low mass DY production Work towards another on exclusive states. Plus continue rest of group programme. 1. Introduction 2. Status of studies 3. Reach with 100 pb -1 4. Conclusions XMAS09 - reminder

4. Achievements/ hardware plans: VELO operations VELO replacement build Upgrade plans (more build) Thanks to all the workshop & downstairs crew.

5. Physics: VELO performance and tracking Themis, David, Kurt, Karol, Abdi, James, Emma, Henry Electroweak Tara, Themis, Kurt, Karol, Stephanie, Emma, Myfanwy, Henry B physics Themis, David, James

6. Why? W/Z provide high p track samples: Tracking performance, track stability, errors, ip Extends ewk: W, tau etc. Optimal tracking needed for B physics Ewk / B can be extended in NP searches in future. Long lived massive particles Boson + heavy flavour

7. BsDsDsBsDsDs + tracking work to optimise lifetime distribution Plots courtesy of James

8. High p T tracking studies Errors, ghosts, preselection, efficiency Muon studies Trigger, identification, backgrounds Electron studies Trigger, identification, backgrounds Theory studies Production studies: Z , W , Z , Z  ee Z  + jet  * ,  *  ee pp  pp+  (luminosity), excl. J/ ,  ' PDF sensitivity studies Underlying event studies A FB *(Liverpool contributions) Electroweak working group + MSTW/NNPDF collaboration (PDFs) + Stirling/Harland- Lang/Khoze (exclusives) + LHC ewk WG (Mangano et al) 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview LHCb kinematic region Predictions of W, Z production Measurement definitions

9. Beam MuonCalo Interaction point Tracking Vertex detector 300mrad Fully instrumented within 1.9 ≤  ≤ 4.9 Trigger: p  > 3 GeV, pt  > 0.5 GeV, m  > 2.5 GeV 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview W, Z production Measurement definitions

10. 2010: 37.7 pb -1 data recorded 16.5 ± 1.7 pb -1 used 2011: hope for 1-2 fb -1 of data 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview W, Z production Measurement definitions

11. 8% of Z within LHCb acceptance 17% (16%) of W + (W - ) within LHCb acceptance 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview W, Z production Measurement definitions

12.   1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview W, Z production Measurement definitions

13. X, Q 2 explored by previous experimental data 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview W, Z production Measurement definitions

14. X, Q 2 explored by LHCb. Z, W: x of 10 -4, 10 -1 (low mass  *  10 -6 ) 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview W, Z production Measurement definitions

15. Cross-sections known to NNLO PDF uncertainty dominates Known to ~1% at y ~1.5-2, 6-8% at y~5 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview W, Z production Measurement definitions

16. Cancel or highlight PDF uncertainties with ratios R + tests d V /u V ratio A W tests difference between u V and d V R WZ almost insensitive to PDFs LHCb 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview W, Z production Measurement definitions

17. 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Overview W, Z production Measurement definitions Definition of measured cross-sections: (as function of Z rapidity) (as function of muon pseudorapidity)

18. Z selection Z background estimation 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

19. Trigger: Single , p T > 10 GeV Muon: Good track quality (  p /p,  2 probability) p T > 20 GeV 2.0 <  < 4.5 Z: 81 < m(  ) < 101 GeV  Z =1.00 (by definition to compare with theory) 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

20. N Z = 833 Backgrounds: Z  ( ~ 0.2 ) Heavy flavour ( ~ 1) K/  ( < 0.03) N bkg = 1.2 ± 1.2 LHCb preliminary Data, simulation 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

21. W selection W background estimation 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

22. Trigger: Single , p T > 10 GeV Muon: Good track quality (  p /p,  2 probability) p T > 20 GeV 2.0 <  < 4.5 Impact parameter significance < 2  p T in R=  (  2 +  2 )=0.5 cone around  < 2 GeV Rest of event: Mass < 20 GeV  p T < 10 GeV  W = 55.0  1.0% (data driven, using Z events) 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

23. LHCb preliminary 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

24. N W+ = 7624 N W - = 5732 Background sources: Z   (1  in acceptance) Z   W   Hadronic events Data Simulation Data + simulation Fit muon p T spectrum in data to expected shapes for signal and background, extract N bkg+, N bkg- 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

25. N bkg+ = 2194 ± 150 N bkg- = 1654 ± 150 Z (fixed with sim)  (fixed and scaled to W) QCD: fit fraction. (shape from data) W+/-: fit fraction (shape from MC) LHCb preliminary ++ -- Perform fit in  bins for differential results 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

26. Measurements made in kinematic acceptance A Z, A W = 1 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

27. Determine from data (Z sample) Tag: 1 identified muon having fired single muon trigger Probe: 1 identified muon 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

28. Efficiency is flat in , p T. No evidence for charge bias  W =72  1%  Z =86  1% LHCb preliminary -- ++   pTpT  1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

29. LHCb preliminary Determine from data (Z sample) Tag: 1 identified muon Probe: 1 muon stub + TT hit (TT not used in tracking) 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

30. Efficiency flat in , p T Two regions considered in   W+ = 73  3%  W - = 78  3%  Z = 83  3% LHCb preliminary (+, - different average efficiency due to different  distribution)  1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

31. Determine from data (Z sample) Tag: 1 identified muon Probe:1 identified track 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

32. Efficiency flat in , p T No evidence of charge bias  W = 98.2  0.5%  Z = 96.5  0.7% LHCb preliminary   data simulation truth level 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

33. Found before: Z: (simulation) 1.00 W: (data driven, using Z events) 55.0  1.0% 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

34. LHCb preliminary MCFM NLO+MSTW08 16.5 pb -1  s=7 TeV Z cross-section 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

35. W cross-section, asymmetry 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

36. LHCb preliminary 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions N Z, N bkg N W, N bkg Efficiencies Results

37. 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Other Z decay channels Exclusive  A FB Other work (briefly): Other Z decay channels Exclusive  A FB

38. … and other channels e.g. Z  ee 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Other Z decay channels Exclusive  A FB

39. … and other channels e.g. Z  1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Other Z decay channels Exclusive  A FB

40. Exclusive  production Two muons: dca<0.15 mm; M  >1 GeV; P T  < 0.9 GeV; SPD multiplicity<5; 0 extra tracks. Exclusive = no charged+neutral activity 1.9<  <4.9 No charged tracks -4<  <-2 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Other Z decay channels Exclusive  A FB

41. 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Other Z decay channels Exclusive  A FB

42. A FB sensitive to sin 2  W Uncertainties from : Forward (quark) direction PDF knowledge of sea LHCb: predominately valence - sea collisions ss contribution reduced Pythia: generator study LHCb 94% correct 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Other Z decay channels Exclusive  A FB

43. Statistical errors only: 1 fb -1 implies 4% statistical precision on A FB implies 0.15% statistical precision on sin 2  W (cf. 0.07% world average) Studies ongoing: PDF uncertainties (estimated at 0.04%) Needs theoretical prediction of comparable precision 1. Introduction 2. Cross-sections 3. Other work 4. Conclusions Other Z decay channels Exclusive  A FB

44. 1. Introduction 2. Cross-sections 3. Oher work 4. Conclusions 2010: Good year for electroweak physics Tested electroweak sector to 6% at LHC First signs of exclusive dimuons 2011: Papers coming More stringent tests of the SM PDF constraints First A FB measurement First B measurements Tracking work allows extension to taus, B and beyond.