Measurements of Electron Charge Mis-identification Rate and Electron Efficiency within SUSY analysis framework Zhichao Zhan SDU Shan Jin IHEP Xueyao Zhang SDU Emmanuel Monnier CPPM FCPPL April 7, 2011 Jinan,China

outline Introduction Tag-and-Probe Method Electron Charge Misidentification Rate Electron Reconstruction Efficiency Conclusion and Prospect

Introduction ATLAS SUSY group has published 2 paper 0lepton channel and 2 lepton channel. Charge mis-identification is the very important part for SUSY 2 same sign lepton final states analysis, which is also an important issue for the physics channel that has lepton charge requirement (SS/OS). Several constituents for charge misidentification Bremsstrahlung;Conversion events;fake electron from jet We try to get a precise charge misidentification rate.

Tag-and-probe Method 1.Good Events(pls see the Appendix) 2. 2 good electrons, one tight tag electron; one probe electron. 3.MissingEt<20GeV 4.dphi(e1,e2)>pi*3/4 Data control sample is fitted by Breit Weigner function convoluted with Gaussian distribution function (Line shape); The background is fitted by Chebyshev polynomials. Definition: Working progress Line shape 4

Object and Bakground check: Electron:Author=1||3; pt>20GeV fabs(ηcalo)<2.47; etcone20<10GeV;ptcone30/pt<0.2 RubustMedium; Electron eta There is no significant discrepancy between MC and data. Electron pt Working progress Data and MC check Electron phi

Electron charge mis-ID rate data~34.3pb-1 @7TeV RobustMedium DATA RobusterTight Left: opposite sign events fitted by line shape right: same sign events fitted by line shape 6

MC RobustMedium RobusterTight Apply the same fit process to MC Zee sample 7

Electron charge mis-ID rate summary RobustMedium RobusterTight |DATA-MC|(%) 0.09±0.24 0.33±0.18 8

Electron efficiency using the same technique RobustLoose RobustMedium RobusterTight Left: the probe electron fulfill three level selection criteria Left: the probe electron fulfill three level selection criteria Right: the probe electron does not pass three level selection criteria 9

Working progress Working progress 10

Left: the probe positron fulfill three level selection criteria Positron efficiency RobustLoose RobustMedium RobusterTight Left: the probe positron fulfill three level selection criteria Right: the probe positron does not fulfill three level selection criteria 11

No difference between positron and electron efficiency Working progress Working progress No difference between positron and electron efficiency 12

Thanks a lot! Merci ~ Conclusion&Prospect Electron charge misidentification rate and electron reconstruction efficiency from Tag-and-Probe method sounds reasonable. Using Tag-and-probe method, we can get a charge mis-identification rate with respect to bin-by-bin pt distribution, when we have enough data statistics. The discrepancy of electron charge misID rate between real data and MC is under investigation Thanks a lot! Merci ~

Lepton Jet&MET Electron : Author=1||3; pt>20GeV Appendix I Electron : Author=1||3; pt>20GeV fabs(η2calo)<2.47;  etcone20<10 GeV;ptcone30/pt<0.2 RubustMedium&&ExpectHitBLayer; Muon: Staco combined; 0<=matchChi2<=100 fabs(η)<2.5; pt>20GeV; etcone20<10 GeV; Jet&MET Jet: AntiKt4Topo; EMJES calibration;  pT>20 GeV, fabs(η)<2.5 MET: MET_LocHadTopo

emf>0.95 && fabs(quality)>0.8 n90<=5 && hecF>0.8 Jet Cleaning: remove events with any jes with pt(EM)>10GeV,satifying: emf>0.95 && fabs(quality)>0.8 n90<=5 && hecF>0.8 |t|>=50ns hecF >= 1 - fabs(quality) Step1:GRL Step2:Trigger Step3:Jet Cleaning Step4:Vertex requirment(Ntrack>4) Step5:Veto events with crack electrons Step7:OR for jets/electrons(remove jets within dR=0.2 of an electron) Step8:Veto events with electron in bad OTX regions Step9:Veto events with muon having|Z0-Zpv|>10mm Step10:Remove electrons/muons within dR=0.4 of a jet Note: use electron cluster(eta,phi)for OTX veto use electron object(eta,phi)for OTX veto

Appendix II 16

Appendix III RobustMedium

tight

Truth tag mis-charge rate. Strategy： Selecte an Electron,which fulfill with pt >20GeV,|eta|<2.47,isEM_tight, author==1||author==3 Tag a truth Electron fufill match(dR<0.1) Calculate its mischarge rate. Working progress Working progress Working progress The charge mis-identification rate from reconstruction is around 0.8%,in the truth tag method measurement 19 19