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Dilepton/Diphoton CSC activities

This paper discusses the investigation of exotic models and the Standard Model side of dilepton and diphoton events with high masses. It covers uncertainties, backgrounds, and the search for new physics. The contents include performances, trigger, electron and muon reconstruction efficiencies, alignment, photon performances, tau reconstruction, and muon trigger.

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Dilepton/Diphoton CSC activities

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  1. Dilepton/Diphoton CSC activities Samir Ferrag University of Glasgow ATLAS UK physics meeting, Durham, 9-11/01/2008

  2. Introduction • Big number of the Exotic Models • Exotic CSC notes: Encompassing all final state topologies to maximise the number of Exotic models to be tested simultaneously. 5 notes investigated • We want it to be one of the first ATLAS Publications: ”Dileptons & Diphotons at high mass” • 2 sides: Understand the Standard Model before looking for BSM • Standard Model side: “Drell-Yan” • Uncertainties from theory PDF,mfact,mren • Corrections: K Factors, EW corrections… . Backgrounds: WW, tt, tt, ECal linearity, charge mis-id, W+jet, g-conversion • Draw the uncertainty band of SM prediction and any deviation of this band signs new physics • Exotic side • S-channel resonances: Z’ ZH,ZKK G • Virtual exchange of gravitons • Leptoquarks, Leptogluons, Heavy scalars (Graviscalar, radion, heavy higgs..) • If the first year collected luminosity will not be enough to discover new physics • Limits on the different models will be included • Wiki page: https://twiki.cern.ch/twiki/bin/view/Atlas/DilepDiphotonResCSCNote…completely outdated

  3. Status of the CSC note • CSC note written • Strategy: • Detector  Standard Model New Physics • Specificities. • High energy performance and trigger investigated regarding the note and there is no reference notes for all of them (electrons, muons, taus and photons) • Special exercise: grouping many new physics: G*, Technicolor and Z’… • Post-note activities: • Refine the CSC note • Still lot of analysis tasks to do (long list) • Many updates has been shown since we froze the draft

  4. Contents of the CSC note

  5. Post CSC… • Uncertainties:first attempt but need more investigations & agreement with others: • Higher order corrections (EW, QCD, N**LL) • Linearity • Alignment • Efficiencies • Luminosity • Backgrounds: • Top, WW, W+jet, tautau, gamma conversion • Fake rate: jet jet, gamma+jet • Exotics: • Statistical methods for resonances: S>>B • ee: • Z’, G*, ADD graviton,heavy scalars, LQ, LG, technicolor • mumu: • Z’, G*, heavy scalars, LQ, LG, technicolor • Tautau: • Z’, G*, heavy scalars, LQ, LG, technicolor • Photon-photon: • G*, heavy scalars, Excited quarks. • Disentangling the underlying models • Electrons: • Contamination: • Jet electron, photonelectron • Lack of efficiencies at high energy • Reported in the note and meeting • Need to develop the eID at high pt • Linearity: • Efficiency measurement from data • Photons: • Efficiency measurement from data • Electron  Photo contamination • Linearity: • Muons: • Efficiency measurement from data • Contamination • Linearity • Trigger: • Menu and rates for L=1033, • What should we use to tag dileptons ? • 2e15i, combined e60+ simply high deposit ?… • What are the trigger rates on s,b • Improve the trigger menu (or slice): • Is it e60 or something else (High Pt deposit).. • Efficiency measurement from data

  6. Note Contents:Performances and Trigger(briefly!)

  7. Electrons reconstruction J. Morel, F. Ledroit

  8. Muon reconstruction efficiencies • Performances: • MC based method • data based (TP ) extrapolated at high Pt • Charge MisID • Effect at high Pt: • Radiation effects more important than minimum ionization effects E. Thompson, J. Love, S. Willocq & J. Butler

  9. Alignment in muon reconstruction • 6 degrees of freedom x,y,z, • 8 configurations are investigated. Each one obtained by performing a random translation on the 6 variables using a gaussian of : 40,100,…,1000 • Nominal configuration corresponds to 40  C. Helsens & CEA

  10. Performances: photons • High energy photons from Gravitons in RS model • Contamination from jets < 10-3 H. Hadvand, B. Kahoe, K. Dinda

  11.  • High Pt  from Z’ decay • Efficiencies after removing the overlaping electrons and muons • Hadronic taus T. Vickey, Z. Czyczula

  12. Trigger: egamma M. Tamsett, A. De Santo X. del Popolo, M. T. Dova Matthew’s talk

  13. Trigger: muons K. Black • L1 trigger: • Barrel: incomplete trigger coverage regarding high precision chambers () • Structure and Feet ()

  14. Trigger:  T. Vickey, Z. Czyczula

  15. Note Contents:Uncertainties on the Standard Model

  16. Limits of the Standard Model • PDF uncertainties: • CTEQ6 40+1 PDF sets • Generator and Reconstructed level • mll,,*… • QCD NLO…K-Factor • Factorisation and QCD renormalisation scale • To be completed by the work presented this morning F. Heinmann, S. Ferrag

  17. Uncertainties: summary

  18. Note Contents:Search of New Physics

  19. Z’ee • Exotic physics probed: • Higher gauge groups, Extra-Dimensions, Dynamic breaking symmetry (Little Higgs) • fit based approach • Same parameterization for ee and signals • BW(m,1)*Landau(m,2) • Parameterization works for both e and  • CLs method used for sensitivity estimation • Combining e and m channels to be done L. Flores

  20. G* ee N. Zhou • Exotic: Extra-dimensions in • Randall-Sundrum geometry • Non parameterized CLs method • (mclimit code by T. Junk)

  21. Z’tt T. Vickey, Z. Czyczula • Complete analysis including Drell-Yan, Di-jets, tt, Z+jets, W+jets, but only Z’ tt@ 600 GeV • In the CSC note: • Only lep-had was investigated • MET Object-Based • Updates: • lep-lep and had-had investigated @ 1 fb-1 • Combined sensitivity • MET RefFinal used • lep-lep: • b-tagging required to lower the tt background • Only visible mass is reconstructed (low stat at 1fb-1)

  22. Z’tt II T. Vickey, Z. Czyczula • Had-had channel: • Promising channel • Sensitivity @ 1fb-1 using visible mass only • Event counting: S/sqrt(B) • Low statistics in full simulation for all backgrounds  difficult to estimate systematics

  23. Exotics: G* • Exotic physics: ExtraDimensions in • Randall-Sundrum geometry • Sensitivity using Event counting: • S=2(Sqrt(S+B)-Sqrt(B)) H. Hadvand, B. Kahoe, K. Dinda

  24. Technicolor in  J. Butler, J. Love • Probed Exotics: Technicolor Snow Mass Models • T,T,T • Statistics: • Event Counting • Non parameterized CLs • Bayesian methods (D0)

  25. Conclusion • Dilepton/Diphoton CSC: • Big number of Exotic models to be tested (or excluded!) simultaneously. • We want it to be one of the first ATLAS Publications: ”Dileptons & Diphotons at high mass” • Draft of the CSC note written: • Detector performances, Standard Model and search of Exotics • All the works inside has been developed for the CSC note • Post-note activities: • Still lot of analysis tasks to do (long list) • Many updates has been shown the last meeting • UK contribution

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