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Study of Z+Jets background Study of Z+Jets background

to SUSY LM1 Pointto SUSY LM1 Point Huseyin TopakliHuseyin Topakli

University of University of ÇÇukurovaukurova

Anwar BhattiAnwar BhattiUniversity of RockefellerUniversity of Rockefeller

Gheorghe Lungu Gheorghe Lungu University of RockefellerUniversity of Rockefeller

12-02-0812-02-08JetMet Topology Group MeetingJetMet Topology Group Meeting

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INTRODUCTIONINTRODUCTION• The Minimal Supersymmetry Model (MSSM) is the minimal

extension of the Standard Model (SM) particle content. Its gauge sector is fully determined by Supersymmetry. The mSUGRA model of supersymmetry is determined by 5 free parameters defined at the Grand Unification (GUT) scale. The free parameters are

In the SUSY signal sample the large MET is resulting from

the two lightest neutralinos in the final states. The missing transverse energy plus multi-jets final state has been a canonical signature for SUSY searches.

parametermixinghiggsnotheofsignthesign

valuesectationvacuumHiggstheofratiothe

couplingtrilinearcommontheA

massgauginocommonthem

scaleGUTtheatmassscalarcommonthem

:)(

exp:tan

"

"

:0

:2/1

:0

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Susy LM1 PointSusy LM1 Point

Low mass test points were chosen to evaluate the sensitivity to SUSY signals in the early period of the LHCbut above the Tevatron reach.

%36)~~(

%46)~~(

%2.11)~~(

~~),~(~

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1

0

2

0

2

lB

B

llB

domiantisqqghenceqmgm

l

R

60

250

Mgluino ~600 GeV Msquark ~ 550 GeV Xsec ~42 pb

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Decays.Decays.

In the SUSY signal sample The large MET is resulting fromThe two lightest neutralinos in thefinal states.

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Estimation of Z->nunu+Jets using Estimation of Z->nunu+Jets using Z->mumu+Jets.Z->mumu+Jets.

• The ratio will be use to

normalize the Z+Jets Monte Carlo predictions.• When we collect real data, the normalization procedure will be

credible if the MEt shape in the simulation for Z->nunu+2Jets is in good agrement with the MEt shape in the Z->mumu+2Jets data.

(a) (b)

))((

))((

JetsZpp

JetsZpp

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Elektroweak Background Elektroweak Background Component (Z+Jets)Component (Z+Jets)

• Major Background: QCD, ttbr,

• Events with large and 3 jets in the final state are expected from

(3. jet originating from the hadronik decay) process.

TE JetsZ 3)(

JetsZ )(

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HT,MHT, HT+MHT Distributions for HT,MHT, HT+MHT Distributions for QCD, LM1 and Z->NuNu Samples.QCD, LM1 and Z->NuNu Samples.

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Analysis Setup.Analysis Setup.• CMSSW_1_6_7 was used

• and samples are CSA07 samples.

• 11 pt bins were used for (0-1TeV) (Pt=20-30,80-120,120-170 were not able to run)

• 13 pt bins were used for (0-1TeV) (Pt=50-80 is not available)

• LM1 Susy Sample was generated by Gheorghe Lungu with

CMSSW_1_5_2

JetsZ )( JetsZ )(

JetsZ )(

JetsZ )(

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Muon Cuts.(Z->mumu+Jets Pt=30-Muon Cuts.(Z->mumu+Jets Pt=30-50GeV)50GeV)

•Pt and Eta cuts applied to each reconstructed muons in order to efficently select the signal and reject the background effects.

Pt>7GeV

|Eta|<2.4

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Z From Muon Pairs(Pt=30-50GeV).Z From Muon Pairs(Pt=30-50GeV).

Z mass cut is |ZMass-91.2|<10GeV

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Pt and Eta distributions of CaloJets Pt and Eta distributions of CaloJets and CorrCaloJets.(Pt=30-50GeV)and CorrCaloJets.(Pt=30-50GeV)

• Eta and Phi cuts were applied to calojets. Pt>14GeV and |Eta|<3.

|JetEta|<3

JetsZ

JetsZ

“CorrJets”“rawJets”

Pt Mean is ~24.5 GeV before corrections, after the correctionsPt mean is ~28.5GeV. Pt is increased ~17% due to corrections.

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Pt of Leading (Cor)CaloJets.Pt of Leading (Cor)CaloJets.

•The blue curve is indicated that Pt is calculated from Zmass window.

No Zmass cut

Zmass Window

)5030()( GeVPtJetsZ

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Pt of Second (Cor)CaloJets.Pt of Second (Cor)CaloJets.)5030()( GeVPtJetsZ

No Zmass Cut

Zmass wind

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Pt of Third (Cor)CaloJets.Pt of Third (Cor)CaloJets.)5030()( GeVPtJetsZ

No Zmass

Zmass Wind

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HT of (Cor)CaloJets.HT of (Cor)CaloJets.)5030()( GeVPtJetsZ

No Zmass Cut

Zmass Win

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MHT of (Cor)CaloJets..MHT of (Cor)CaloJets..)5030()( GeVPtJetsZ

From Met Object

Red curves indicates that No Zmass cut. Blue curves indicates that from Z mass window.

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Xsec_Vs_Lead(Cor)CaloJetPtXsec_Vs_Lead(Cor)CaloJetPt

Due to missing Pt range (80-120,120-170GeV)

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XSec_Vs_Second(Cor)CaloJetPtXSec_Vs_Second(Cor)CaloJetPt..

XSec_Vs_Thrd(Cor)CaloJetPtXSec_Vs_Thrd(Cor)CaloJetPt..

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XSec_Vs_HT(Cor)CalJetsXSec_Vs_HT(Cor)CalJets

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XSec_Vs_MHT(Cor)CalJetsXSec_Vs_MHT(Cor)CalJets

If JetsSize>=2 and MHT>100GeV

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missEt From CaloMet Obj.missEt From CaloMet Obj.

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Next Things.Next Things.

• Use corrected muons • Use the Type-I Met correction• Use Z->ee+Jets samples.