1. Observation and measurement of HW+W-

2. Part 1: INTRODUCTION

3. Contents Introduction Analysis overview
Data samples and reconstruction
Event selection
Signal processes
Background processes
Fit procedure and uncertainties
Yields and distributions
Results and interpretations
Part 1
Part 2
Part 3
Part 4
Part 5
This is a paper of 73 pages/~90 editors!

4. Introduction Motivation of the work Review of current status
Production channels
Overview of the results
Paper structure

5. Analysis Overview : major background

6. Analysis Strategy: Categorization
Discriminating variables (BDT for VBF, MT for ggF)

7. Part 2: Detector and samples

8. 大型强子对撞机（LHC） 位于欧洲核子研究中心（CERN） 周长27km，跨越瑞士法国国境，总投资40亿美元
日内瓦湖
Large Hadron Collider 机场
CMS
ATLAS
LHCb
ALICE
大型强子对撞机（LHC）
位于欧洲核子研究中心（CERN）
LHC time line :
1992 : expressions of interest
: LHC TDR published
: first pp collisons at CME=900 GeV
2010.2: first pp collisions at CME=7 TeV
2011: CMS and ATLAS recorded ~5/fb of data
2012: CMS and ATLAS ~20/fb at CME=8 TeV
2015 – 2018 data-taking at CME = 13 TeV m
周长27km，跨越瑞士法国国境，总投资40亿美元
世界能量最高最大的加速器，设计质心系能量14TeV(14x1012eV) 8 8 8

9. Length: ~ 46 m Radius : ~ 12 m Weight : ~ 7000 tons Channels: ~ 108
Muon spectrometer
air-core toroids,
MDT+RPC+TGC+CSC
s/pT ~ 2-7 %
|h| < 2.7, |h|<2.5 ( precision
phys.)
Length: ~ 46 m
Radius : ~ 12 m
Weight : ~ 7000 tons
Channels: ~ 108
Lcable: ~ 3000 km
Cost: 541M CHF
EM Calorimetry
Pb-LAr
s/E ~ 10%/√E(GeV)1%
|h|<3.2, |h| < 2.5 (fine granularity)
Inner detector (B=2 T)
Si pixels and strips
Transition Radiation Detector
(e/ separation)
s/pT ~ 0.05% pT(GeV)0.1%;
|h| < 2.5, B=2 T(central solenoid)
Hadron Calorimeter
Fe/scintillator (central), Cu/W-LAr (fwd)
s/E ~ 50%/√E(GeV)3%
||<3

10. ATLAS TDAQ

11. Detector and data samples
Coordinate system
Trigger
Data: 2011, 7 TeV 4.5fb-1, 2012, 8 TeV, 20.3 fb-1
Reconstruction
Vertex / Electron/ Muon /lepton isolation/ Jet / b- tagging / MET (METrel) pTMiss, pTMiss(track)

12. MC simulations

13. Part 3: Event selection

14. Event selection : Initial sample
Initial sample: pT1>22 GeV, pT2>10 GeV, Opposite charge, no 3rd lepton(with pT>10 GeV), vertex, trigger.
𝑒𝜇 channel: 1.33*105 events, expect 800 signal events) , sqrt(1.33E+5) = 365.
𝑒𝑒/𝜇𝜇 channel: 1.6*107 events

15. DISCUSSION Mar 23 Why 𝑠/ 𝐵 , not 𝑠/√(𝑆+𝐵) ? (see page 14)
Definition of METrel

16. JVF

17. Event selection

18. Distributions after preselection

19. Discriminating variables of nj=0

20. Discriminating variables for nj=1

21. Discriminant variable for nj=2(VBF)

22. nj=2, ggF

23. Cut-flow : nj=0

24. Cut flow: nj = 1

25. Cut-flow(nj>=2, VBF)

26. BDT analysis for VBF

27. Cut-flow nj>=2, ggF

28. mT : fitting variable

29. BDT output: fitting variable

30. Kinematics in Signal regions(1)

31. Kinematics in Signal region(2)

32. Event display

33. Are we done yet?

34. Part 4: Signal and Background

35. Signal processes Theory
Cross sections at NNLO in QCD, NLO in EWK. (10% uncert)
ggF: resummation to NNLL.
BR(HW+W- ) =22% (4.2% relative uncertainty)

36. Signal processes Theory
Cross sections at NNLO in QCD, NLO in EWK. (10% uncert)
ggF: resummation to NNLL.
BR(HW+W- ) =22% (4.2% relative uncertainty)

37. Background processes WW Top Mis-identified leptons (Wj + jj)
Other dibosons
Example: nj=0 SR 𝑀 𝑙𝑙 <55 GeV , ∆𝜑(𝑙𝑙) < 1.8
WW CR 55< 𝑀 𝑙𝑙 <110 GeV, ∆𝜑(𝑙𝑙) < 2.6

39. WW CR  SR (nj <= 1) nj<=1 : CR – SR 𝑀 𝑙𝑙 extrapolation
Selected with 𝑒𝜇 events
𝑝 𝑇 𝑙2 >15 GeV
nj=0: 𝑝 𝑇 𝑙𝑙 >30 GeV, ∆𝜑 𝑙𝑙 >2.6, 55< 𝑀 𝑙𝑙 <110 GeV
nj=1: 𝑚 𝑇 𝑙 >50 GeV, 𝑀 𝑙𝑙 > 80 GeV

40. Systematic uncertainties
WW CR  SR (nj <= 1)
Systematic uncertainties
nj<=1 : CR  SR 𝑀 𝑙𝑙 extrapolation

41. WW MC (nj>=2)
nj>=2: SHERPA MC, normalized with MCFM(large top-quark contribution, CR difficult to define for WW)
Validation region: MT>100 GeV, MT2>160 GeV
Data/MC ratio in validation region:

42. Top quarks (nj=0)
nj=0: CR= preselection, 𝑒𝜇 channel, ∆𝜑(𝑙𝑙) <2.8, any nj
Purity : 74%
Correction to the “extrapolation factor” alpha determined with 1 b-tag CR:1.006
Total uncertainty: 8%

43. Top quarks (nj=1)
CR: preselection, 𝑒𝜇 channel only, exactly 1 jet (b- tagged) MTl > 50 GeV
Extrapolating from 1-btag to 0-btag
Total uncertainty: 5%

44. Top quarks (VBF: nj >=2 )
CR: exactly 1 b-tag.
BDT analysis, ttbar MC modeling systematics

45. Top quarks (ggF, njet>=2)
Defined with 𝑀 𝑙𝑙 >80 GeV (70% purity)
Uncertainty on the extrapolation factor < 4%

46. Fake lepton: W+j CR: one lepton “anti-identified”.
Extrapolation factor: measured from Z+jets
Background famine in “identified lepton” at high pT

47. Misid extrapolation factor

48. Multi-jet CR: two anti-identified leptons
Fake factor measured with multi-jet sample, applied twice. ARE WE DOULE COUNTING multi-jet?

49. Other dibosons
𝑊𝛾,𝑊𝑍/ 𝛾 ∗ , 𝑍𝑍 (10% of total background, same magnitude as the signal)
𝑒𝜇 channel: same sign CR for normalization
𝑒𝑒/𝜇𝜇: MC for both normalization and shape
Validation : Electron with no b-layer hit to catch 𝑊𝛾(photon conversion also studied with 𝑍→𝜇𝜇𝛾)
𝑊𝑍/ 𝛾 ∗ Validation : 𝑒𝜐𝜇𝜇, 𝑀 𝜇𝜇 < 7 GeV, pTmiss > 20 GeV

50. Same sign CR

51. 𝑊𝛾,𝑊𝑍/ 𝛾 ∗ validation

52. Drell Yan : Z𝜏𝜏 CRs nj=0: 𝑀 𝑙𝑙 <90 GeV, ∆𝜑(𝑙𝑙) >2.8, purity:91%
nj=1: 𝑀 𝑙𝑙 <80 GeV, 𝑀 𝜏𝜏 > (mZ-25 GeV) (collinear approximation), purity: 80%
nj>=2 ggF: 𝑀 𝑙𝑙 <70 GeV, ∆𝜑(𝑙𝑙) >2.8 purity 74%
nj>=2 VBF: 𝑀 𝑙𝑙 <80 GeV (75 for 𝑒𝑒/𝜇𝜇 ) , | 𝑀 𝜏𝜏 – mZ|<25 GeV

53. Drell Yan CR

54. DY 𝑒𝑒/𝜇𝜇 in nj<=1
Matrix method using frecoil cut : uncertainty ~ 50%

55. DY 𝑒𝑒/𝜇𝜇in nj>=2 VBF
ABCD method using pTmiss and 𝑀 𝑙𝑙

56. Summary of CRs

57. Summary of corrections from CR
Are we done yet?

58. Part 5: Fit and results

59. Fit regions : SR

62. Likelihood function, and LLR

63. Uncertainty on signal

64. Uncertainty on background

65. Post-fit uncertainties (%)

66. Checks of the fit (ranking plot)

67. Post-fit yields

68. Post-fit MT (nj=0/1 𝑒𝜇 )

69. Post-fit MT nj=0,1 𝑒𝑒/𝜇𝜇

70. Post-fit MT (nj>=2 ggF VBF Cross-Check)

71. VBF (BDT analysis)

72. Observation!

73. Signal strength

74. Mass and signal strength

75. Ratio of VBF/ggF signal strengths

76. Signal strengths

77. Uncertainties

78. “Exclusion plot”