1. 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

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

3. 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.

4. 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

5. 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

6. Electron charge mis-ID rate
RobustMedium
DATA
RobusterTight
Left: opposite sign events fitted by line shape
right: same sign events fitted by line shape 6

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

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

9. 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

10. Working progress
Working progress 10

11. 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

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

13. 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 ~

14. 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

15. 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

16. Appendix II 16

17. Appendix III
RobustMedium

18. tight

19. 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