== electron mis-charge rate measurement of www analysis cristinel diaconu, yanwen liu, emmanuel...

= =Electron Mis-Charge Rate Measurement of WWW

AnalysisCristinel Diaconu, Yanwen Liu, Emmanuel Monnier,Ruiqi Zhang

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Introduction

To estimate the background with electron charge mis-identification, we need to measure the charge mis-identification rate. The muon mis-charge rate is negligible.

Rates are measured using Z->ee events selected from data with likelihood method. Truth method using Z->ee MC as cross check.

Use template method to subtract the background contribution in the rates and treat it as systematic. Compare the truth rates measured with Zee MC and WZ MC.

Requested by the SM convener.

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Likelihood and Truth Methods

• Electrons are divided into different eta/pT bins since mis-charge rates are related to their eta/pT.• Etbins:{15.,30.,40.,50.,60.,80.,120.,1000.} GeV• Etabins:{0.,0.8,1.15,1.60,1.80,2.0,2.2,2.3,2.4,2.5}

• Likelihood Method• Use Tminuit to calculate, Ntot and Nss(events with a pair of same sign electrons) are input.

• Truth Method• Compare the electrons’ charge with truth charge of coresponded true electron.• Two cluster electron A,B and two true electrons decayed from Z in Z->ee MC.• Calculate deltaR of any possible combination.• If dR[A,C]+dR[B,D] > dR[A,D]+dR[B,C], A matched with D and B matched with C.• Else A matched with C and B matched with D.

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Event and Electron Selection

• Event Selection• Trigger : EF_e24vhi_medium1 or EF_e60_medium1• Exactly 2 electrons passing electrons selection.• Trigger Match, |InvMee-Zmass|<10 GeV.

• Electron Selection• Author 1 or 3 and OQ.• Fabs(eta)<2.47 and crack region removed.• pT>15 GeV• TightPP• Etcone20/pT<0.10 for pT>20 GeV and Etcone20<0.07 for pT<20 GeV• Ptcone20/pT<0.04• |d0/sigmad0|<3.0• |z0*sin(theta)|<0.5• Elec/elec and elec/muon overlap removal.

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Likelihood & Truth Rates from MC

Rates here are measured from Z->ee MC samples.LL Rates agree well with truth rates considering their stat errs except two bins(the first one whose LL rate is extremely small and the second one is Etabin1,Etbin0)

Likelihood method is ok through this comparison.

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LL Rates from data with stat errors

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Background Subtraction

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Method

• In Tminuit, Ntot and Nss(with a pair of same sign electrons) are input.• Use Template fit to get the background amount in Ntot and Nss which are input for Tminuit.

• Need background and signal InvMee shapes as templates• Use Z->ee MC and the WWW electron selection to get the signal template.• Use polynomial fit to get the background template.

• Need signal and background InvMee passing background selection from data.• Because events are divided into many bins according to eta/et of their electrons.

• Have to merge the bins to get more statictic to do fit.• Will show the results with etbins merged.

• Events will be divided into 9*9 etabins.• Will show the background subtraction of [etabin0,etabin2] in detail.

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InvMee Selections• Signal

• Event Selection• Trigger : EF_e24vhi_medium1 or EF_e60_medium1• Exactly 2 electrons passing electrons selection.• Trigger Match, |InvMee-Zmass|<10 GeV.

• Electron selection• WWW electrons selection except z0 and pT.

• Z0 is 0.5mm and pT is 15GeV.• Background

• Event Selection• Trigger : EF_e24vhi_medium1 or EF_e60_medium1• Choose the leading and subleading electrons and at least one of these 2 electrons stastified the

background electron selection and use those 2 electrons to calculate the InvMee.• Electron Selection

• Pass author,pT,eta,OQ and fail isolation and TightPP.

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InvMee Hists

Background Mee from Egamma Zee passing Bkg selection This is the Mee in [etabin0,etabin2] of Ntot

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Polynomial Fit Use 4th order polynomial function and Zee passing bkg selection to fit the "Bkg" hist measured from Egamma samples. Show polynomial fit of [etabin0,etabin2].

Blue is fit.Red is Signal.Orange is polynomial function.Black is "Bkg" from data.

More plots of polynomial fit at：/afs/cern.ch/user/r/ruzhang/public/Plots/z005/polynomial

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Template Fit

Use Mee from Zee MC as signal template and the polynomial function fitted before as bkg to fit Mee from Egamma. Show the fit of [etabin0,etabin2].

Blue is fit.Red is Signal.Orange is polynomial function.Black data.

More plots of polynomial fit at：/afs/cern.ch/user/r/ruzhang/public/Plots/z005/template

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fSig and its error of Ntot

Two tables here show the fSig measured with template fit and its statistic errors for Ntot.

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fSig of NssBecause the statistic of Nss events is not enough to do fine fit. So we get the global fSig of Nss and Nos. And define SF = global_fSig_Nss/global_fSig_Nos.

Left is Polynomial fit for Bkg.Right is Template fit for data.Orange is Bkg, Red is Zee and black is data. Blue is fit.fSig is 0.9372Err is 0.00415

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fSig of Nss(2)Global fSig of Nos is 0.9921, global fSig of Nss is 0.9372, so reweight fSigs of Nos with this SF, then we can get the fSigs of Nss in different bins. Left is Nss and right is Nos.

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Background systematic

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Comparison with WZ rates

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Introduction

• Apply the truth method to Z->ee and WZ MC samples. • mc12_8TeV.129880.PowhegPythia8_AU2CT10_WZ_Wm13Z11_mll5p0d0_mll30GeV.merge.NTUP_SMWZ.e1524_s1499_s1504_r3658_r3549_p1328• mc12_8TeV.129889.PowhegPythia8_AU2CT10_WZ_W13Z11_mll5p0d0_mll30GeV.merge.NTUP_SMWZ.e1524_s1499_s1504_r3658_r3549_p1328

• For lacking of statistic, set fewer bins here.• Etabin : 0.,1.15,1.80,2.2,2.5• Etbin : 0.,60.,100.,1000. GeV

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Truth Rate Comparison

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Summary

• The electron mis-charge rate measurement of WWW analysis is presented.• Use the rates measured from Z->ee events selected from data with LL method.• Rates with truth method as cross check.

• Background subtracted and treated as systematic.• Comparison with WZ truth rates done.• Compatible between Z->ee MC and WZ MC.