1. Lei Zhang on behalf of HSG5 1 st July 2013 Unblinding approval for VH(bb) 1

2. Outline of this talk Brief overview of the analysis strategy: – Event selection – Background modeling – Statistical interpretation Questions from the last unblinding talk Conclusion 2

3. Trigger and Event Selection Zero lepton: MET triggerOne lepton: 1-Lepton trigger + MET trigger (for muon channel) Two lepton: 1-Lepton trigger + 2-lepton trigger Common selection: – At least 2 jets in |eta|<2.5 Pt1>45GeV, Pt2>20GeV – Veto forward jets with Pt>30GeV (0/1 lepton) – Lepton: Loose (Pt>10GeV) and Tight/Medium (Pt>25GeV) – 2 b-tagged jets (MV1@70%) PtV (GeV)0-9090-120120-160160-200>200 dR(jet,jet)0.7-3.40.7-3.00.7-2.30.7-1.8<1.4 0 lepton: – No loose leptons and Etmiss (PtZ)>120 GeV QCD rejection cuts: – Δφ(Et miss, jets) > 1.5 – Δφ(Et miss, Pt miss )< π/2 – Δφ(Et miss, bb) > 2.8 1 lepton: – 1 tight leptons and No additional lepton QCD rejection cuts: – Pt W 40GeV – Pt W >200, Et miss >50GeV 2 lepton: – 1 medium + 1 loose lepton – No additional lepton – 81GeV < M ll < 99GeV – Et miss <60GeV – QCD negligible 3

4. Dataset and background modeling background modeling: Diboson: – Using MCFM(NLO) generator level study – 5-60% uncertainty has been applied according to the process and Vpt – Additional 2 jet /3 jet ratio uncertainty has been implemented – Systematics depends on njets as wel (the bulk of the difference comes in the 3-jet channel) Single top Pt top : – Compare different MC and shower tunes : 1-4% uncertainty Ttbar Pt top reweighting: – Using ATLAS 7TeV unfolded measurement to correct the top pt before showering. – Apply 50% of the correction as systematics V+jets dPhi modeling: – Correction on V+jets dPhi improves aggreement in other varialbes, e.g. Vpt – Apply 50% of the correction as systematics – Generator level study has been performed to understand the source of dPhi mis-modeling Mbb systematics: – Compare different shower model and generators to estimate the Mbb systematics MC sample:WH/ZHMulti-jetttbarSingle topW+jetsZ+jetsDi-boson 2011 / 2012Pythia8Data-drivenPowheg + PythiaPowheg + AcerMCSherpa Pythia / Herwig Full Run-1 data: 5fb -1 @7TeV and 21fb -1 @8TeV 4

5. Top p T reweighting and systematic https://cds.cern.ch/record/1470588 Used Powheg-Pythia with Perugia tune Very small difference. Top p T mean shifted by 1.85% ‣ ttbar events: reweight truth top p T to unfolded 7TeV data ‣ applied to both 7 and 8 TeV => checked absence of bias ‣ alters mass as well as p T 5

6. W+jets dPhi modeling correction W+jets Wjets Wp T @8TeV Before reweighting After reweighting and dR cut Still some residual mismodeling at high Vp T => add a systematic of 2% and 4% in the last two bins Correction of V+jets dPhi to data improves agreement in other variables, like V p T Apply a systematic of 50% the correction Decorrelated in flavor and jet multiplicity => 12 parameters Z+jets case could be found in backup. 6

7. dPhi generator level studies on Wbb ‣ Cross checked if Sherpa vs aMCatNLO discrepancy can be covered by physics motivation ‣ No big effect on dPhi from pdf, renormalisation and factorisation scale variations in aMCatNLO aMC@NLO vs Powheg vs Sherpa Renormalization Scale PDF sets Factorization Scale ‣ Generator studies of Wbb dPhi(b,b) distribution => help understand dPhi mismodeling in Sherpa ‣ Clear slope in comparison between NLO MCs and Sherpa (multileg) 7

8. Vpt shapes: 1-lepton Pt binning is: 0-90, 90-120, 120-160, 160-200, 200- The Wl normalization is float. 8

9. Fitting model 2jets, 1-tags3jets, 1-tags2jets, 2-tags3jets, 2-tagsTop emu CR 0-leptonNorm Shape - 1-leptonNorm Shape - 2-leptonNorm Shape Norm Flavor composition treatment: –Correlate: Wcc, Wbb and Wbl with 30% relative uncertainty; –Keep separate Wcl ; –Fix Wl with 10% uncertainty. –Analogous splitting for Z+jets 9

10. Constraining Systematics Uncertainties Theory/Modeling: – Mbb shape – Vpt and Top pt – Jet multiplicity Migration between channels through lepton sysetmatics Experimental: – JER/JES – B-tagging – Lepton ID – MET For each channel For each bin For each P T V bin 10

11. 2011 and 2012 Fitting parameter correlation (I) 11

12. Samplem BB NP Wt ISR/FSR Hadronization DR vs DS : corr. s-chan t-chan ttbarPowheg : corr Wbb Sherpa/aMC@NLO : corr Wbl Wcc Wcl Sherpa/aMC@NLO : corr Wl Zbb Data/MC comparison in 0Tag : corr Zbl Zcc Zcl Zl MJ template changes : un-corr 12 dPhi: uncorr dPhi 3Jet/2jet ratio: uncorr 3 jet / 2 jet ratio: uncorr 2011 and 2012 Fitting parameter correlation(II)

13. To do list from last talk Understand precisely the origin of the constraint on the JER. Is its modeling sufficient? Investigate all its correlations. Clarify all correlations of the nuisance parameters in Chiara's list. –Top pT, 3/2 ratio –MJ normalisation –DPhi –BTagC5Effic, BTagB2Effic –JES constraints (1-lepton, fluctuation ) –Jet Flav composition (David) –MET Trigger systematic ( sys itself is small ) Add the multijet (in the 1 lepton analysis) to Chiara's list of parameters to be investigated. Perform a complete comparison of the NPs between 7 TeV and 8 TeV. Give the diboson results for 7 TeV. Thanks Eilam and Marumi 13

14. NP check on 7TeV fit Top Ten Impact on mu 14 To be updated

15. NP check on 8TeV fit 8TeV 15 Top Ten Impact on muhat 15 To be updated

16. B-tag NPs check 8TeVB-tag 16 7TeV

17. B-tagging check Eigen state scale factor variation at the jet pt base. 17

18. Unfolded b-tagging efficiency 8TeV7TeV 18

19. JES NPs check 8TeV 19 7TeV

20. MET trigger Trigger scale factor: – Using leptonic trigger to select Wmunu events – Taking the fraction of the events passing MET trigger as efficiency. – Scale factor = Eff data /Eff MC Statistical uncertainty: due to statistical error from the fit Process and generator: comparison between W+jet, Z+jets and ttbar. 20

21. The Jet resolution uncertainty we are using could be too conservative, which could cause the constraining in fitting. 21 Jet resolution

22. JES fluctuation and constrain 22 Fluctuation in the Mbb shape Remaining effect after smoothing procedure.

23. Smooth model Smoothing can reduce the constrains a lot. Re-bining the histograms until the stat. uncertainty of the ratio nominal/syst. less than 5%. After smoothing, it still leaves large variations in some bins (maybe why some are still constrained) 23

24. Dphi NPs check 8TeV 24 7TeV WDPhiWDPhi_3jetZbDPhi

25. Dphi sys check 8TeV fit: 8TeV fit: combined 25

26. 26 Separate fit in each lepton channels

27. Scale factor 8TeV 27 7TeV

28. 8TeV 28 7TeV Normalization NP check

29. Top Pt NP check Top Pt 8TeV 29 7TeV

30. Top Pt and 3jet/2jet ratio check Top pT, 3jet / 2jet ratio: Several tests have been done: – Split NP for each N Jet, M btag bin (as the bottom plot). – Split NP for High and Low Vpt Mbb. –3jet / 2jet of ttbar: increase error by factor of 10 More detailed study can be found: –https://indico.cern.ch/getFile.py/access?contribId=1&resId=1&materialId=slides&confId=260550https://indico.cern.ch/getFile.py/access?contribId=1&resId=1&materialId=slides&confId=260550 –Proposal: de-correlated the normalization effect and Mbb shape effect. 30

31. Mbb NP check Top Mbb Mbb Zbb Mbb 8TeV Mbb 31

32. m bb shape systematics Samplem BB NP Wt ISR/FSR Hadronization DR vs DS s-chan t-chan ttbarPowheg Wbb Sherpa/aMC @NLO Wbl Wcc Wcl Sherpa/aMC @NLO Wl Zbb Data/MC comparison in 0Tag Zbl Zcc Zcl Zl MJ template changes 32

33. Summary of problematic NPs 8TeV 33 MJ normalization: 7TeV

34. NP check (need plots!!) –MJ normalization: –Anti-correlated with Whf –Add ranking later 34 To be updated

35. 35

36. 36 Correlation check: 7TeV

37. High correlation NPs 37 Correlation check: 7TeV

38. 38 B-tag

39. 39 JES

40. 40 Modeling

41. 41 Mbb NP

42. 42 Norm

43. 43 Scale factor

44. Correlation check: 8TeV 44

45. 45 Correlation check: 8TeV High correlation NPs

46. 46 B-tag

47. 47 JES

48. 48 Modeling

49. 49 Mbb

50. 50 Norm

51. 51 Scale factor

52. 7-8 TeV combined NP check Problematic NPs 52

53. Correlation 53

54. To be updated 54 Recap of the correlation check

55. B-tag: C5 has been pulled due to the large fraction of the charm composition of top background in the high Vpt bins. JER: due to the conservative JER uncertainty we are using. JES: some of them may come from the fluctuation. MET trigger NP has been pulled, but considering its small uncertainty, the overall impact should be small. Dphi Top Pt/Mbb : To be updated 3jet/2jet ratio: 55 Recap of NP check

56. Scale factor and summary of muhat value Scale factors: Summary of muhat values for diboson 56

57. Post-fit: M JJ in 0-lepton 57 MET>200 GeV 2 tag 2 jetMET>200 GeV 2 tag 3 jet In clusive MET, 1 tag 2 jetIn clusive MET, 1 tag 3 jet

58. Post-fit: M JJ in 1 lepton 58 Vpt>200 GeV 2 tag 2 jetVpt>200 GeV 2 tag 3 jet In clusive Vpt, 1 tag 2 jetIn clusive Vpt, 1 tag 3 jet

59. Post-fit: M JJ in 2 lepton 59 In clusive Vpt, 1 tag 2 jetIn clusive Vpt, 1 tag 3 jet Vpt>200 GeV 2 tag 2 jetVpt>200 GeV 2 tag 3 jet

60. Expected limit (later) Combined 0+1+2 : 1.19 +1.66 -0.86 0-lepton : 1.91 + 2.65 -1.37 1-lepton : 1.94 +2.70 -1.40 2-lepton: 3.10 + 4.32 -2.24 7TeV expected limit and p0 Combined expected limit and p0 60

61. Conclusion Ready for approval 61

62. backup 62