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03/02/2010 Physics & Computing in ATLAS

A photon selection from Z->ee g decay for the calibration of the LAr calorimeter with photons. Evgeny Yu Soldatov , Anatoli Romaniouk Moscow Engineering Physics Institute. 03/02/2010 Physics & Computing in ATLAS. The goal.

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03/02/2010 Physics & Computing in ATLAS

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  1. A photon selection from Z->eegdecay for the calibration of the LAr calorimeter with photons. Evgeny Yu Soldatov, Anatoli Romaniouk Moscow Engineering Physics Institute 03/02/2010 Physics & Computing in ATLAS

  2. The goal Identification of the photos from this process and optimization of the signal/background ratio 03/02/2010 Physics & Computing in ATLAS

  3. Signal and backgrounds (truth level) 03/02/2010 Physics & Computing in ATLAS

  4. DeltaR distribution between photon (jet) and closest electron Final State Radiation – our Signal Initial State Radiation Brem in material Truth Jets as a photons 03/02/2010 Physics & Computing in ATLAS

  5. DR cut selection. Overall signal statistics loss & efficiency of photon reconstruction VS DR cut. Efficiency Statistics loss DR>0.2 always used further 03/02/2010 Physics & Computing in ATLAS

  6. ETdistribution of truth photons from FSR (signal), ISR and Brem in material • - FSR • - ISR • Brem in material • Jets are not shown 03/02/2010 Physics & Computing in ATLAS

  7. distribution of truth photons from FSR, ISR and Brem in material - FSR - ISR - Brem in material Bream in material is a tiny fraction of the background. 03/02/2010 Physics & Computing in ATLAS

  8. ETanddistributions for truth jets ET  Some fraction of these truth jets will be reconstructed as a photons and this is the most significant background for the signal. 03/02/2010 Physics & Computing in ATLAS

  9. Distribution of truth invariant mass for FSR, ISR and Jets FSR ISR Truth Jets 03/02/2010 Physics & Computing in ATLAS

  10. Reconstruction/truth comparison 03/02/2010 Physics & Computing in ATLAS

  11. ETanddistributions of the reconstructed FSR photons (signal) matched with truth and the reconstruction efficiency. • without tight cut • - with tight cut Efficiency Et (MeV) Et (MeV) Efficiency   03/02/2010 Physics & Computing in ATLAS

  12. ETanddistributions for reconstructed ISR photons (background) matched with truth and reconstruction efficiency ET Efficiency • without tight cut • - with tight cut  Efficiency 03/02/2010 Physics & Computing in ATLAS

  13. Residual distribution for the reconstructed invariant mass of the signal and truth. 03/02/2010 Physics & Computing in ATLAS

  14. Reconstruction (all particles) 03/02/2010 Physics & Computing in ATLAS

  15. ET and  distributions of the all reconstructed photons (with and without tight cut) ET  ET  With tight cut With tight cut The peak around half Z-boson mass corresponds to an error in the reconstruction of the conversion photon from one of the Z-boson’s electron. 03/02/2010 Physics & Computing in ATLAS

  16. InvM distributions for all reconstructed photons All events Dataset 106050, statistics 4.8M events Signal Bkg 03/02/2010 Physics & Computing in ATLAS

  17. InvM distributions for all reconstructed photons with tight cut All events Here and on all next slides tight cut is always used Signal Bkg 03/02/2010 Physics & Computing in ATLAS

  18. Invariant Mass distributions of the signal statistics loss and s/b ratio (integral from 0) as a function of upper InvM threshold Statistics loss S/B ratio On the basis of these plots an upper three-particle invM limit was chosen as 96 GeV. 03/02/2010 Physics & Computing in ATLAS

  19. Invariant Mass distributions of the signal statistics loss and s/b ratio (integral for fixed upper limit of 96 GeV) as a function of bottom InvM threshold Statistics loss S/B ratio On the basis of these plots a bottom limit of the three-particle invM was chosen as 80 GeV. 03/02/2010 Physics & Computing in ATLAS

  20. Two electrons Invariant Mass distributions of the signal statistics loss and s/b ratio (integral from 0) as a function of upper InvM ee threshold Statistics loss S/B ratio On the basis of these plots an upper two-particle invMee limit was chosen as 80 GeV. 03/02/2010 Physics & Computing in ATLAS

  21. Two electrons Invariant Mass distributions of the signal statistics loss and s/b ratio (integral for fixed upper limit of 80 GeV) as a function of bottom InvM ee threshold S/B relation Statistics loss On the basis of these plots an bottom two-particle invMee limit was chosen as 50 GeV. 03/02/2010 Physics & Computing in ATLAS

  22. Dependence of the statistics loss, s/b relation from upper deltaR cut S/B relation Statistics loss 03/02/2010 Physics & Computing in ATLAS

  23. ET distributions of the signal statistics loss, s/b relation and efficiency as a function of down ET threshold Statistics loss Efficiency S/B relation 03/02/2010 Physics & Computing in ATLAS

  24. + dRup cut S/B 6.8 Statistics loss 59% No cuts + Et threshold 0.18 9 0% 66% Tight cut 0.45 26% + invM upper cut 3.08 32% + invM down cut 3.78 35% + invM ee upper cut 5.47 51% + invM ee down cut 6.10 54% Table of Statistics loss and S/B relation for all cuts

  25. Summary Optimization of the S/B for Z-boson decay process has been done. S/B ratio approximatelly 9. Other processes (for example Z->mumugamma) is in investigation now.

  26. Backup slides 03/02/2010 Physics & Computing in ATLAS

  27. Et andetadistribution of the truth and reconstructed (in photon container) jets and efficiency of reconstruction 03/02/2010 Physics & Computing in ATLAS

  28. Ratio of the truth Signal/Background as a function of invariant mass in window 03/02/2010 Physics & Computing in ATLAS

  29. InvM distributions for signal, background and s/b (with and without tight cut) 03/02/2010 Physics & Computing in ATLAS

  30. Two electron Invariant Mass distribution for signal, background and S/B relation (with and without tight cut) 03/02/2010 Physics & Computing in ATLAS

  31. Two electron Invariant Mass distribution for signal, background and S/B relation (with and without tight cut) in window 03/02/2010 Physics & Computing in ATLAS

  32. Et distributions of the signal, background, s/b and efficiency as a function of upper Et threshold 03/02/2010 Physics & Computing in ATLAS

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