Study of Z+Jet in CMS

Transcription

1 Study of Z+Jet in CMS Bibhuti Parida Gagan Mohanty, Tariq Aziz DHEP, TIFR India-CMS collaboration meeting December 2011 at University of Delhi 1

2 Outline Introduction Feynman Diagram Dataset and MC used Pre-selections Kinematic distributions Summary and plan India-CMS collaboration meeting December 2011 at University of Delhi 2

3 Introduction One of the primary goals for the LHC experiments is to find the Holy Grail of electroweak symmetry breaking by discovering the Higgs boson or disproving its existence A potential Higgs discovery channel is the vector boson fusion (VBF) process in which two W or Z bosons are fused together to produce the Higgs (VV H) Two forward jets, separated by a large rapidity gap, accompany the Higgs boson in this process The Z+jet final state constitutes a stepping stone toward the VBF study India-CMS collaboration meeting December 2011 at University of Delhi 3

4 Channel under Study The leading order Feynman diagrams for the Z+jet process are shown below. Here the final state consists of two oppositely charged leptons and either a quark or a gluon jet India-CMS collaboration meeting December 2011 at University of Delhi 4

5 What we want to do? Want to measure the transverse momentum balance of the Z-boson and the accompanying jet. Compute calibration coefficients from the quark jets using the formula C( E j j T, raw, ) P j E Z T T, raw cq k q q g q Where q and are the ratios of Z g q and Z g cross sections to the total Z + jet cross section evaluated from theory. We will then compare the performance between Calo, Jpt and Pf jets India-CMS collaboration meeting December 2011 at University of Delhi 5

6 Dataset and MC used Data: /DoubleMu/Run2011A-May10ReReco-V1/AOD /DoubleMu/Run2011A-PromptReco-v4/AOD MC: /DYJetsToLL_TuneZ2_M-50_7TeV-madgraph-tauola/Summer11- PU_S4_START42_V11-v1/AODSIM CMSSW version: CMSSW_4_2_5 Global tags: GR_R_42_V12 for Data START42_V12 for MC Corrections: L1Offset, L2Relative and L3Absolute are applied for both data and MC samples Event selection relies on identifying a Z boson and a back-to-back jet in the transverse plane, where the Z is reconstructed out of the two isolated leptons For this analysis the e + e and µ + µ final states are considered India-CMS collaboration meeting December 2011 at University of Delhi 6

7 Pre-selections The muon selection cuts used are described below : 1. Muons to be identified as a global muon candidates found in the muon system are extrapolated back into the tracker as this extrapolation provides a more precise measurement of muons 2. Two oppositely-charged high Pt muons (Pt > 20 GeV/c) 3. Global track-fit chi square < Muon d0 < Muon Relative Isolation < 0.2, where Relative Isolation = (Muon Track Isolation + Muon Calo. Isolation)/ Muon Pt 6. ΔR(muon, jet) > The di-muon invariant mass between 85 and 97 GeV/c 2 8. η < 2.4 for the di-muon system 9. ΔΦ between the Z and the most-energetic jet > 2.97 rad India-CMS collaboration meeting December 2011 at University of Delhi 7

8 The electron selection cuts used are below: 1. Electrons are identified by combining a supercluster in the ECAL with a matched track in the TRACKER 2. Two oppositely-charged high Pt electrons (Pt > 20 GeV/c) 3. Track-fit χ 2 < Electron loose Id > 0 5. Electron Relative Isolation < 0.1 where, Relative Isolation = (Electron Track Isolation + Electron Calo Isolation)/ElectronPt 6. ΔR(electron, jet) > The di-electron invariant mass between 85 and 97 GeV/c 2 8. η < 2.4 for the di-electron system 9. ΔΦ between Z and the most-energetic jet is > 2.97 rad India-CMS collaboration meeting December 2011 at University of Delhi 8

9 Kinematic Distributions(Muon Properties) for Data: Number of good muons 1 st Muon Charge 2 nd muon charge India-CMS collaboration meeting December 2011 at University of Delhi 9

10 Kinematic Distributions(Muon Properties) for Data(Contd..) Transverse momentum distribution of reconstructed 1 st muon candidates with Pt > 20 Gev/c Transverse momentum distribution of reconstructed 2nd muon candidates with Pt > 20 Gev/c Pseudo-Rapidity distribution of 1 st muon candidates without any eta cut. Pseudo-Rapidity distribution of 2 nd muon candidates without any eta cut India-CMS collaboration meeting December 2011 at University of Delhi 10

11 Kinematic Distributions(Muon Properties) for Data (Contd...) Phi distribution of 1 st muon candidates Phi distribution of 2 nd muon candidates Track Isolation of 1 st muon candidates Track Isolation of 2 nd muon candidates India-CMS collaboration meeting December 2011 at University of Delhi 11

12 Kinematic Distributions(Muon Properties) for MC Number of good muons 1 st Muon Charge 2 nd Muon Charge India-CMS collaboration meeting December 2011 at University of Delhi 12

13 Kinematic Distributions(Muon Properties) for MC (Contd..) Transverse momentum distribution of reconstructed 1 st muon candidates with Pt > 20 Gev/c Transverse momentum distribution of reconstructed 2 nd muon candidates with Pt > 20 Gev/c Pseudo-Rapidity distribution of 1 st muon candidates without any eta cut. Pseudo-Rapidity distribution of 2 nd muon candidates without any eta cut India-CMS collaboration meeting December 2011 at University of Delhi 13

14 Kinematic Distributions (Muon Properties) for MC (Contd..) Track Isolation of 1 st muon candidates Track Isolation of 1 st muon candidates India-CMS collaboration meeting December 2011 at University of Delhi 14

15 Kinematic distributions(jet Properties) for Data Calo Jet, Jpt Jet and PF Jet Multiplicities with Pt > 20Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 15

16 Kinematic distributions(jet Properties) for Data (Contd..) Transverse momentum distribution of 1 st energetic Calo Jet, Jpt Jet and Pf Jets with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 16

17 Kinematic distributions(jet Properties) for Data (Contd..) Pseudo-rapidity distribution of 1 st energetic Calo Jet, Jpt Jet and Pf Jets with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 17

18 Kinematic distributions(jet Properties) for Data (Contd..) Phi distribution of 1 st energetic Calo Jet, Jpt Jet and Pf Jets with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 18

19 Kinematic Distributions (Jet Properties) for MC sample : Jet multiplicity distributions for Calo, Jpt and PF jets respectively 03/01/2012 India-CMS collaboration meeting December 2011 at University of Delhi 19

20 Kinematic distributions (Jet Properties) for MC sample (Contd ) : Transverse momentum distributions of 1 st energetic Calo Jet, Jpt Jet and Pf Jet with Pt > 20 Gev/c 03/01/2012 India-CMS collaboration meeting December 2011 at University of Delhi 20

21 Kinematic Distributions (Jet Properties) for MC sample (Contd..) Pseudo-rapidity distributions of 1 st energetic Calo Jet, Jpt Jet and Pf Jet with Pt > 20 Gev/c 03/01/2012 India-CMS collaboration meeting December 2011 at University of Delhi 21

22 Kinematic distributions (Jet Properties) for MC sample (Contd..) Phi distributions of 1 st energetic Calo jet, Jpt Jet and Pf Jet with Pt > 20 Gev/c 03/01/2012 India-CMS collaboration meeting December 2011 at University of Delhi 22

23 Kinematic Distributions ( Di-muon properties) for Data Transverse momentum distribution of the Z boson reconstructed from di-muons without any Pt cut Transverse momentum distribution of Z boson reconstructed from dimuons without any Pt cut and in the range 85 GeV/c 2 < Mµ + µ - < 97 Gev/c 2 Pseudo rapidity distribution of the Z boson reconstructed from di-muons without any Eta cut Pseudo rapidity distribution of the Z boson reconstructed from di-muons with η < India-CMS collaboration meeting December 2011 at University of Delhi 23

24 Kinematic Distributions (Di-muon properties) for Data(Contd ) Phi distribution of Z boson reconstructed from dimuons Phi distribution of Z boson reconstructed from dimuons within the mass window 85 GeV/c 2 < Mµ + µ - < 97 Gev/c 2 Mass of the Z boson reconstructed from muons without any cut. Mass of Z boson reconstructed from muons in the window 85 GeV/c 2 < Mµ + µ - < 97 Gev/c 2 and 2.4 < η < India-CMS collaboration meeting December 2011 at University of Delhi 24

25 Kinematic Distributions (Delta phi between Z and jet) for Data(Contd ) Angular separation of Z boson and highest Pt jets. Z and jet are considered to be back-to-back if ΔΦ > India-CMS collaboration meeting December 2011 at University of Delhi 25

26 Kinematic Distributions (Ratio of (Z Pt - Jet Pt )/Z Pt ) for Data(Contd ) India-CMS collaboration meeting December 2011 at University of Delhi 26

27 Kinematic Distributions (Di-muon properties) for MC Transverse momentum distribution of Z boson reconstructed from dimuons without any Pt cut Transverse momentum distribution of Z boson without any Pt cut and in the range 85 GeV/c 2 < Mµ + µ - < 97 Gev/c 2 Pseudo rapidity distribution of Z boson reconstructed from di-muons without any Eta cut. Pseudo rapidity distribution of Z boson reconstructed from di-muons with -2.4< η< India-CMS collaboration meeting December 2011 at University of Delhi 27

28 Kinematic Distributions (Di-muon properties) for MC (Contd ) Phi distribution of Z boson reconstructed from dimuons Phi distribution of Z boson reconstructed from dimuons in the range 85 GeV/c 2 < Mµ + µ - < 97 Gev/c 2 Z boson mass reconstructed from dimuons Z boson mass reconstructed from dimuons within the mass window 85 GeV/c 2 < Mµ + µ - < 97 Gev/c 2 and -2.4< η< India-CMS collaboration meeting December 2011 at University of Delhi 28

29 Kinematic Distributions ( Electron properties) for MC Number of good isolated electrons 1 st Electron Track Isolation 2 nd Electron Track Isolation India-CMS collaboration meeting December 2011 at University of Delhi 29

30 Kinematic Distributions ( Electron properties) for MC Transverse momentum of 1 st electron candidates reconstructing Z mass with Pt> 20 Gev/c Transverse momentum of 2 nd electron candidates recunstructing Z mass with Pt > 20 Gev/c Psudo rapidity distribution of 1 st electron candidates reconstructing Z mass with Pt> 20 Gev/c Psudo rapidity distribution of 2 nd electron candidates reconstructing Z mass with Pt> 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 30

31 Kinematic Distributions ( Electron properties) for MC (Contd..) Phi distribution of 1 st electron candidates reconstructing Z mass with Pt> 20 Gev/c Phi distribution of 2 nd electron candidates reconstructing Z mass with Pt> 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 31

32 Kinematic Distributions (di-electron properties) for MC (Contd ) Transverse momentum distribution of Z boson reconstructed from di-electrons without any Pt cut Transverse momentum distribution of Z boson reconstructed from di-electrons without any Pt cut in the range 85 GeV/c 2 < Mµ + µ - < 97 Gev/c 2 and -2.4< η< 2.4 Pseudo rapidity distribution of Z boson reconstructed Pseudo rapidity distribution of Z boson reconstructed from di-electrons with 85 GeV/c from di-electrons without any Eta cut. 2 < Mµ + µ - < 97 and - 2.4< η< India-CMS collaboration meeting December 2011 at University of Delhi 32

33 Kinematic Distributions (di-electron properties) for MC (Contd ) Phi distribution of Z boson reconstructed from di electrons Phi distribution of Z boson reconstructed from dielectrons with 85 GeV/c 2 < Mµ + µ - < 97 and -2.4< η< 2.4. Mass of Z boson reconstructed from identified and isolated electrons Mass of Z boson reconstructed from identifies and isolated electrons in the window 85 GeV/c 2 < Me + e - < 97 Gev/c 2 and with -2.4 < η < India-CMS collaboration meeting December 2011 at University of Delhi 33

34 Summary and Plan: The proposed method utilizes clean Z+ Jet events as these are almost background free apart from a negligible background from QCD. The preliminary study of Z+ jet with different kinematic distributions of leptons and jets are presented Smaller data and MC samples are used, need to study higher statistics with better understanding of the background contribution, normalization and uncertainties and theoretical interpretation of results In VBF process, two forward jets are produced and these tagging jets are separated by a large rapidity gap. Jet energy correction of the tagging quarks in the Vector Boson Fusion production of Higgs boson is required to be analyzed India-CMS collaboration meeting December 2011 at University of Delhi 34

35 India-CMS collaboration meeting December 2011 at University of Delhi 35

36 Backup India-CMS collaboration meeting December 2011 at University of Delhi 36

37 Kinematic distributions for Data (Contd..) B tag discriminator distributions of 1 st, 2 nd and 3 rd energetic Pf jets with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 37

38 Kinematic distributions for MC sample (Contd..) B tag discriminator distributions of 1 st, 2 nd and 3 rd energetic Pf jets with Pt > 20 Gev/c 03/01/2012 India-CMS collaboration meeting December 2011 at University of Delhi 38

39 Rapidity distribution of 1 st muon candidates without any eta cut. Rapidity distribution of 1 st muon candidates with 85 GeV/c 2 < Mµ + µ - < 97 Gev/c 2 and 2.4 < η < 2. 4 Rapidity distribution of 2 nd muon candidates without any eta cut. Rapidity distribution of 2 nd muon candidates with 85 GeV/c 2 < Mµ + µ - < 97 Gev/c 2 and 2.4 < η < India-CMS collaboration meeting December 2011 at University of Delhi 39

40 Transverse Momentum distribution of 2 nd energetic Calo Jet, Jpt Jet and Pf Jets with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 40

41 Pseudo rapidity distribution of 2 nd energetic Calo Jet, Jpt Jet and Pf Jets with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 41

42 . Phi distribution of 2 nd energetic Calo Jet, Jpt Jet and Pf Jets with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 42

43 Kinematic Distributions (Jet properties) for MC Jet multiplicity distributions for Calo, Jpt and PF jets respectively India-CMS collaboration meeting December 2011 at University of Delhi 43

44 Kinematic Distributions (Jet properties) for MC(Contd..) Transverse momentum distributions of 1 st energetic Calo Jet, Jpt Jet and Pf Jet with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 44

45 Kinematic Distributions (Jet properties) for MC(Contd..) Pseudo-rapidity distributions of 1 st energetic Calo Jet, Jpt Jet and Pf Jet with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 45

46 Kinematic Distributions (Jet properties) for MC(Contd..) Phi distributions of 1 st energetic Calo jet, Jpt Jet and Pf Jet with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 46

47 Kinematic Distributions (Jet properties) for MC(Contd..) Pt distribution of 2 nd energetic Calo Jet, Jpt Jet and Pf Jet with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 47

48 Kinematic Distributions (Jet properties) for MC(Contd..) Eta distribution of 2 nd energetic Calo jet, Jpt Jet and Pf jet with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 48

49 Kinematic Distributions (Jet properties) for MC(Contd..) Phi distributions of 2 nd energetic Calo jet, Jpt Jet and Pf jet with Pt > 20 Gev/c India-CMS collaboration meeting December 2011 at University of Delhi 49