First Look at H→ WW → lepton + Ω Analysis Ajay Kumar...
Transcript of First Look at H→ WW → lepton + Ω Analysis Ajay Kumar...
First Look at H→ WW*→ lepton + h
Analysis
Ajay Kumar , Arun Kumar, Dr. Kirti Ranjan
University of Delhi
India CMS Meeting, 22-23 December 2011
@ University of Delhi, New Delhi 1
Overview
Motivation
Introduction
Samples and Software
Event Selection
Data/MC comparison
First Look at Boosted Decision Tree (BDT)
Summary and Future Plan
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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 115 -127GeV from H-> , H->WW->2l2 and H ->bbbar. Additionally, ATLAS has also seen 1.4 in H->WW->2l2nu at Mh=126 GeV.
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Decay modes & BR (2/3)
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2/3
1/3 Low Mass region Mh<130 GeV H , H , H bb are explored. Mass Region M->115-130GeV : needs to explored extensively now.
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Introduction (3/3)
Signal: 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
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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_160404-173692_7TeV_PromptReco_Collisions11_JSON.txt (~2.1 fb-1)
S/W : For Data : CMSSW_4_2_5 For MC : CMSSW_4_1_8
Physics Analysis Toolkit (PAT) objects used.
Spring 11 MC samples are used.
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MC samples (details)
Samples (σ) * (B.R) (pb) Processed Events
Skimmed
Events
Expected
Events** at
L = 2.036 fb-1
Scaling
factor at
L = 2.036 fb-1
ggH->WW->e+ 0.1029 1.1E+5 7.2E+4 138 0.00191
W+Jets 31314 (NNLO) 2.1E+6 7.8E+5 2.4E+7 30.67
TTJets 157.5(NLO &
NNLL) 1.1E+6 9.0E+5 27.0E+4 0.30
WW 43 (NNLO) 2.1E+6 1.2E+6 5.1E+4 0.04246
WZ 18.2 (NLO) 2.1E+6 1.1E+6 2.0E+4 0.01757
ZZ 5.9 (NLO) 2.1E+6 4.3E+5 2.5E+3 0.00570
Drell Yan 3048 (NNLO) 1.5E+6 7.2E+5 3.0E+6 4.14
** skimming: at least one electron and one tau in |h| < 2.5
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Event Selection (1/2) Trigger
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*
No Trigger in MC till now. Primary vertex
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
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Event Selection (2/2)
Electron Selection
|η| < 2.5 , pT > 20 GeV , 1.4442 < |h| < 1.566 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
Pile Up Interaction Distributions
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Red: MC Black: Data
Red: MC Black: Data
Without Pileup Reweighting With Pileup Reweighting
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 : https://twiki.cern.ch/twiki/bin/viewauth/CMS/PileupMCReweightingUtilities
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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 : Data
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DATA/MC Comparison Plots (2/3)
Tau PT Tau Eta Tau Phi
Red : W+Jets Violet : DYJets Cyan : TTJets Yellow : WW Blue : WZ Green : ZZ Black line : Signal (glu-glu) Black Dots : Data
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DATA/MC Comparison Plots (3/3)
Dphi (e,tau)
Dphi (e,MET) Dphi (tau,MET) Minimum Transverse Mass of W (GeV)
Projected MET (GeV) PF MET (GeV)
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Boosted Decision Tree (TMVA based)
Cuts Applied: Ele PT > 10 GeV ,Tau PT > 10 GeV, ProjMET >10GeV
Inclusive jets input variables Distribution
Blue - Signal Red – combined Background
Input variables
chosen for
training, testing
Ele PT
Min(MT)
of W Proj_MET
dPhi (e,)
Tau PT
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Zero jet One jet >one jet
Signal (S) .004 .015 .006
Total bkg (B) .043 .043 .603
S/B .089 .36 .010
S/sqrt(S+B) .018 .064 .007
Signal and Background
After putting BDT cut
No optimization done
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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.
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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
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Color scheme for overlapping plots :
Color scheme for stack plots:
S/B maximization in different jet bins
with different cuts
Note: Signal significance = s/sqrt(signal+background) extreme signal significance = signal/sqrt(background)
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(c) (b) (a)
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
S/B maximization for inclusive jets with
different cuts
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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)
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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)
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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)
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Maximum a b c
signal(s) .015 .006 .029
bkg(b) .12 .085 3.7
s/b .127 .067 .008
s/sqrt(s+b) .042 .019 .015
Tables for various jet-bins Inclusive Jets
Maximum a b c
signal(s) .004 .004 .006
bkg(b) .043 .043 .043
s/b .089 .089 .135
s/sqrt(s+b) .018 .018 .026
Zero Jets
Maximum a b c
signal(s) .015 .011 .002
bkg(b) .043 .361 .06
s/b .360 .032 .032
s/sqrt(s+b) .064 .019 .008
One Jet
Maximum a b c
signal(s) .006 .012 .010
bkg(b) .603 1.53 5.19
s/b .010 .008 .002
s/sqrt(s+b) .007 .009 .004
More than One Jets
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.
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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).
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ATLAS With current data set ATLAS has excluded 112.7-115.5GeV and 131-453GeV (except for 237-251GeV) 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)
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.
Current Status of higgs searches
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HLT_IsoMu12_LooseIsoPFTau10_v* HLT_IsoMu15_LooseIsoPFTau15_v*
For Muons+Tau:
|η| < 2.4, pT > 20GeV
Number of Hits > 10
Pixel hits >= 1
Matched stations >= 2
(PT)/PT < 0.1
2 < 10
Isolation(rho-corrected) < 0.15
Muon Selection:
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IsoECAL : The sum of electromagnetic transverse energy of the crystals lying in a cone of ΔR = 0.4, centred around the super-cluster 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.
Some definitions
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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
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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!
PAT