First Look at H WW * lepton + h Analysis. University of Delhi. Ajay Kumar, Arun Kumar, Dr. Kirti Ranjan

Transcription

1 First Look at H WW * lepton + h Analysis Ajay Kumar, Arun Kumar, Dr. Kirti Ranjan University of Delhi India CMS Meeting, December University of Delhi, New Delhi 1

2 Overview Motivation Introduction Samples and Software Event Selection Data/MC comparison First Look at Boosted Decision Tree (BDT) Summary and Future Plan 2

3 Motivation *H WW * 2l2 is well explored channel at CMS in the final states ee,,e +MET in the mass range 110 to 600GeV. *Highest BR above higgs mass of 125GeV *Relatively good S/B Ratio * More sensitivity to di-leptonic channels by studying l+ h final state. * More challenging because of tau & MET in final state. * In addition to H-> & H-> ZZ->4l channels, CMS has seen modest excess of events in region GeV from H->, H->WW->2l2 and H ->bbbar. Additionally, ATLAS has also seen 1.4 in H->WW->2l2nu at M h =126 GeV. 3

4 Introduction: (1/3) Higgs Production at LHC 4

5 Decay modes & BR (2/3) 1/3 2/3 Low Mass region M h <130 GeV H, H, H bb are explored. Mass Region M-> GeV : needs to explored extensively now. 5

6 Signal: Introduction (3/3) H WW * l+ h where l is either e or µ and decays hadronically. At present, considered only electron with gluon-gluon fusion production at Higgs Mass of 160 GeV Muon, VBF mode will be added. whole mass range will be added. Backgrounds: W+Jets : Most dominant background,due to jet faking lepton TTJets : Second dominant Diboson a.) WW : Irreducible b.) WZ : when one lepton from Z is lost c.) ZZ : minimal contribution, lepton faking as tau Drell-Yan : fake MET 6

7 Samples and Software Data: /TauPlusX/Run2011A-May10ReReco-v1/AOD /TauPlusX/Run2011A-PromptReco-v4/AOD /TauPlusX/Run2011A-05Aug2011-v1/AOD /TauPlusX/Run2011A-PromptReco-v6/AOD JSON: Cert_ _7TeV_PromptReco_Collisions11_JSON.txt (~2.1 fb -1 ) Spring 11 MC samples are used. S/W : For Data : CMSSW_4_2_5 For MC : CMSSW_4_1_8 Physics Analysis Toolkit (PAT) objects used. 7

8 MC samples (details) Samples (σ) * (B.R) (pb) Processed Events Skimmed Events Expected Events** at L = fb-1 Scaling factor at L = fb-1 ggh->ww->e E+5 7.2E W+Jets (NNLO) 2.1E+6 7.8E+5 2.4E TTJets 157.5(NLO & NNLL) 1.1E+6 9.0E E WW 43 (NNLO) 2.1E+6 1.2E+6 5.1E WZ 18.2 (NLO) 2.1E+6 1.1E+6 2.0E ZZ 5.9 (NLO) 2.1E+6 4.3E+5 2.5E Drell Yan 3048 (NNLO) 1.5E+6 7.2E+5 3.0E ** skimming: at least one electron and one tau in h < 2.5 8

9 Trigger Event Selection (1/2) Lepton +Tau Lowest threshold unprescaled triggers have been used. Same as used in H analysis. HLT_Ele15_CaloIdVT_CaloIsoT_TrkIdT_TrkIsoT_LooseIsoPFTau15_v* HLT_Ele15_CaloIdVT_CaloIsoT_TrkIdT_TrkIsoT_LooseIsoPFTau20_v* HLT_Ele18_CaloIdVT_CaloIsoT_TrkIdT_TrkIsoT_LooseIsoPFTau20_v* HLT_Ele18_CaloIdVT_CaloIsoT_TrkIdT_TrkIsoT_MediumIsoPFTau20_v* HLT_Ele15_CaloIdVT_CaloIsoT_TrkIdT_TrkIsoT_TightIsoPFTau20_v* Primary vertex No Trigger in MC till now. Primary Vertices reconstructed with DA Algorithm. Ndof >= 4.0 && Rho < 2.0mm && abs(z) < 24cm Tau Selection PFTaus reconstructed with HPS algorithm has been used. All prong decays considered. η < 2.5 and pt > 20 GeV AgainstElectronTight (mva based discriminator) AgainstMuonLoose (tau lead track not matched to chamber hits) LooseIsolation 9

10 Event Selection (2/2) Electron Selection η < 2.5, pt > 20 GeV, < h < excluded Electron ID VBTF WP80 has been used (details in back up) Relative Combined Isolation < 0.1 (fast-jet corrected) Vertexing cuts : dz < 0.1cm and dxy <0.02cm Further cuts : Events having exactly 1 lepton + 1 tau has been selected after applying this selection on leptons and taus. R (e, tau) > 0.7, opposite charge PF Jets with L1 and L2 Corrections are selected with pt > 10GeV and dr from lepton and tau > 0.5 Projected MET > 20 GeV Pre-selection = Skimming + Tau Selection + Electron Selection + Further cuts 10

11 Pile Up Interaction Distributions Without Pileup Reweighting With Pileup Reweighting Red: MC Black: Data Red: MC Black: Data No. of PU interactions No. of PU interactions PU-Reweighting has been applied for in-time PU only using the official recipe mentioned on twiki : 11

12 DATA/MC Comparison Plots (1/3) Electron PT Electron Eta Electron Phi Red : W+Jets Violet : DYJets Cyan : TTJets Yellow : WW Blue : WZ Green : ZZ Black line : Signal (glu-glu) Black Dots 12 : Data

13 DATA/MC Comparison Plots (2/3) Tau Eta Tau Phi Tau PT Red : W+Jets Violet : DYJets Cyan : TTJets Yellow : WW Blue : WZ Green : ZZ Black line : Signal (glu-glu) Black Dots 13 : Data

14 DATA/MC Comparison Plots (3/3) Dphi (e,tau) Projected MET (GeV) PF MET (GeV) Minimum Transverse Mass of W (GeV) Dphi (e,met) Dphi (tau,met) 14

15 Boosted Decision Tree (TMVA based) Inclusive jets input variables Distribution Cuts Applied: Ele PT > 10 GeV,Tau PT > 10 GeV, ProjMET >10GeV Blue - Signal Red combined Background Ele PT Tau PT dphi (e, ) Min(M T ) of W Proj_MET Input variables chosen for training, testing 15

16 BDT output alljets = 0 jet = 1jet > 1 jet 16

17 Signal and Background After putting BDT cut Zero jet One jet >one jet Signal (S) Total bkg (B) S/B S/sqrt(S+B) No optimization done 17

18 Summary Had first look at H WW l+ analysis. Data/MC comparison plots are shown for various kinematic and other discriminating variables. No major discrepancy seen. TMVA BDT was applied on 5 input variables Future Plan 1. Try to optimize our selection. More variables will be added to BDT -- include more discriminating variables like b-tagging etc to reduce tt-jets contamination. 2. Include VBF signal and also Mu+tau to increase sensitivity. 3. For estimating backgrounds we will use data-driven techniques. 4. Need to switch to Summer 11 MC and ultimately to Fall 11 MC with whole 2011 data. 5. Volunteered for Trigger and DQM online shifts for 2012 Run. 18

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21 WP80 21

22 DATA/MC Comparison Plots (6/6) Invariant Mass of (e,tau) Transverse Mass of Higgs 22

23 TMVA (Toolkit for Multivariate Data Analysis) BDT (boosted decision tree) method chosen Pile UP Reweighted Signal to background ratio maximization Input variables chosen for training, testing Electron Transverse Momentum (PT) Tau Transverse Momentum Azimuthal angular separation of lepton and tau (dphi) Minimum Transverse Mass of W boson Projected Missing Transverse Energy Sensitivity study in following Jet bins: All jets Zero jet One jet More than one jets 23

24 BDT Working 24

25 S/B maximization in different jet bins with different cuts Color scheme for overlapping plots : Note: Signal significance = s/sqrt(signal+background) extreme signal significance = signal/sqrt(background) Color scheme for stack plots: 25

26 S/B maximization for inclusive jets with different cuts a.) Ele PT>10, Tau PT>10, ProjMET >10GeV b.) Ele PT>20, Tau PT>20, ProjMET >10GeV c.) Ele PT>20, Tau PT>20, ProjMET >20GeV (a) (b) (c) 26

27 S/B maximization for 0-jet with different cuts a.) Ele PT>10, Tau PT>10, ProjMET >10GeV b.) Ele PT>20, Tau PT>20, ProjMET >10GeV c.) Ele PT>20, Tau PT>20, ProjMET >20GeV (a) (b) (c) 27

28 S/B maximization for 1-jet with different cuts a.) Ele PT>10, Tau PT>10, ProjMET >10GeV b.) Ele PT>20, Tau PT>20, ProjMET >10GeV c.) Ele PT>20, Tau PT>20, ProjMET >20GeV (a) (b) (c) 28

29 S/B maximization with > 1- jet with different cuts a.) Ele PT>10, Tau PT>10, ProjMET >10GeV b.) Ele PT>20, Tau PT>20, ProjMET >10GeV c.) Ele PT>20, Tau PT>20, ProjMET >20GeV (a) (b) (c) 29

30 Tables for various jet-bins Inclusive Jets Zero Jets Maximum a b c signal(s) bkg(b) s/b s/sqrt(s+b) One Jet Maximum a b c signal(s) bkg(b) s/b s/sqrt(s+b) Maximum a b c signal(s) bkg(b) s/b s/sqrt(s+b) More than One Jets Maximum a b c signal(s) bkg(b) s/b s/sqrt(s+b)

31 Correlation Matrix

32 Correlation Matrix 32

33 Training and Testing Plot 33

34 BDT Training, Testing, Correlation scatter plots 34

35 BDT Control Plots 35

36 Anatomy of the excess Best fit / sm of the various channels 36

37 CMS New Limits to Higgs Mass The presence of the SM Higgs boson below 127GeV has not been excluded because of a modest excess of events in the region between 115 and 127GeV. The excess at low mass is produced by a broad excess driven by the low resolution channels (H2TT, H2WW, H2BB), modulated by the localized excesses seen by the high resolution channels (H2GG and H2ZZ). CMS has established a new 95% CL exclusion limits: 127GeV- 600GeV. The excess is most compatible with a SM Higgs hypothesis in the vicinity of 124 GeV and below, but the statistical significance (2.6σ local and 1.9σ global after correcting for the LEE in the low mass region) is not large enough to say anything conclusive. 37

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39 We cannot exclude the presence of the SM Higgs boson below 127GeV because of a modest excess of events in the region between 115 and 127GeV. The excess at low mass is produced by a broad excess driven by the low resolution channels (H2TT, H2WW, H2BB, center), modulated by the localized excesses seen by the high resolution channels (H2GG and H2ZZ, right). 39

40 Limits on / sm (CLs method) 95%CL: obs , exp: GeV 40

41 Current Status of higgs searches CMS CMS has established a new 95% CL exclusion limits: 127GeV- 600GeV. The excess is most compatible with a SM Higgs hypothesis in the vicinity of 124 GeV and below, but the statistical significance (2.6σ local and 1.9σ global after correcting for the LEE in the low mass region) is not large enough to say anything conclusive. ATLAS With current data set ATLAS has excluded GeV and GeV (except for GeV) ATLAS is now competing with LEP's low mass results! There is a large deviation in p0- values at 126GeV. 1.9e-4, or an excess of 3.6sigma (gamma gamma 2.8 has sigma, ZZ* has 2.1, WW* has 1.4sigma) 41

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43 Measure Background process Drell yan process W+Jets process ttbar process 43

44 Muon Selection: For Muons+Tau: HLT_IsoMu12_LooseIsoPFTau10_v* HLT_IsoMu15_LooseIsoPFTau15_v* η < 2.4, pt > 20GeV Number of Hits > 10 Pixel hits >= 1 Matched stations >= 2 (PT)/PT < < 10 Isolation(rho-corrected) <

45 CaloID_VT: H/E hh TrkId_T h CaloIso_T TrackIso_T EcaiIso/ET HcaiIso/ET TrkIso/ET 45

46 Some definitions IsoECAL : The sum of electromagnetic transverse energy of the crystals lying in a cone of ΔR = 0.4, centred around the supercluster with a veto cone (ΔRi = 3.5 crystals) and eta-slice (Δη = 2.5 crystals) should be less than the threshold value. IsoHCAL : The sum of hadronic transverse energy of all the particles in the HCAL towers in a hollow cone with an inner radius of ΔRi = 0.15 and an outer radius of ΔRo = 0.4 centred around the super-cluster should be less than a threshold value. IsoTrk : The sum of transverse momenta of all the tracks in a full cone (ΔR = 0.4) centered around line joining the primary vertex to the cluster should be less than a threshold value. H/E : - The fraction of hadronic energy to the total electromagnetic energy inside a cone. Σiηiη : - The transverse shape of the electromagnetic cluster. 46

47 PFTaus reconstructed with HPS algorithm has been used. All prong decays considered. η < 2.5 and pt > 20 GeV DecayMode Finding AgainstElectronTight: PFemva <-0.1, tau is not in ECAL crack and a.)if tau has no EM constituents H/P >0.08 B.)if tau has EM constituents fbrem<0.99ormt>0.55 AgainstMuonLoose LooseIsolation 47

48 PAT PAT summarizes information for you: The reco::candidate is a base class common to all kind of particles It has a lot of information from different subdetectors and reconstruction algorithms Facilitated Access to Event Information PAT objects summarize this information which is distributed over different collections When you are using PAT it is just calling a member function to get this information! 48