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Progress of GMSB with photons

Progress of GMSB with photons. Shilei Zang University of Colorado, Boulder. F.Santanastasio , D.del Re, S.Rahatlou , B.Hirosky , B.Cox , M.Balazs , J. Jones, R.Stringer , B.Heyburn , U.Nauenberg , Y.Gershtein , A.Askew. Exotica Meeting, 13 June 2008. People Involved.

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Progress of GMSB with photons

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  1. Progress of GMSB with photons ShileiZang University of Colorado, Boulder F.Santanastasio, D.del Re, S.Rahatlou, B.Hirosky, B.Cox, M.Balazs, J. Jones, R.Stringer, B.Heyburn, U.Nauenberg, Y.Gershtein, A.Askew Exotica Meeting, 13 June 2008

  2. People Involved Colorado: Bernadette:Skims, Fastsim validation; EW bkg Shilei: trigger studies; QCD bkg; analysis variable Florida: Andrew: QCD bkg; common code Yuri: All backgrounds Maryland: Francesco: Photon selection (ORCA); EW bkg (ORCA); common code; signal extraction Riverside: Robert: common code; EW bkg Rome: Daniele, Shahram: EW bkg (ORCA); Skims; All analysis Virginia: Brad, Michael, Bob, John: MC generation; improved analysis; photon selection; beam halo

  3. Photon ID Francesco Santanastasio Optimized selections in ORCA (standard cuts): • HLT: S, RS, D, RD (PDPhoton) • Offline Isolation: trkIso<9GeV; H/E<0.1 • Others: Pt1>90GeV; Pt2>30GeV; Eta<1.479 trkIso: total Pt of tracks inside the cone of ΔR<0.3 H/E: Hcal tower energy within ΔR<0.3over Ecal energy. trkIso<9GeV implies “track un-match” for photons Next: • Better track match for electrons; otherwise (un-match) for photons • Update photon ID from Virginia, cluster shape etc.

  4. Photon ID B. Cox, M. Balazs, J. Jones • Photon selection improvements • Additional use of cluster shape • Work in progress (presented at photon+X LPC) • Beam halo rejection GM1e Beam halo • Ecal timing distribution for GMSB and Beam Halo

  5. Trigger Studies Shilei Zang • Improve trigger efficiency for GMSB (see CMS IN-2008/016) • Trigger inefficiency from isolation. • Suggested two triggers: p-EMHighEt (pH): Et>80GeV; Itrack<4 (1.39Hz); (drop Ecal and Hcal isolation; default rate~ 0.63Hz) p-EMVeryHighEt (pVH): Et>160GeV (0.36Hz); (default one: Et>200GeV; 0.13Hz) Rate increase about 1Hz. Trigger efficiency (D, H, VH) from 86% to ~92%. • Suggest to use 3 triggers (D, pH, pVH)(2.0Hz; 92%) • Or 4 triggers (RS, D, H, VH) (3.7Hz; 90%); or (RS, H, VH). ! Now (CSA07): PDPhoton: S, RS, D, RD; Next (CSA08?): PDPhoton: S, RS, D, RD, H, VH? 5

  6. Fastsim Validation Bernadette Heyburn • 7000 GMSB events for both Fastsim and Fullsim • Agree well for all variables, except that photon energy (or Pt), which is a common problem for all Fastsim validation. Reco MET Gen-Reco Pt Gen-Reco E

  7. Strategy for background studies • Fake MET: QCD with direct photons or jets misidentified as photons. (qcd+jets; photon+jets) • Real MET: Electron-photon mis-identification: W(enu)+gamma; W(enu)+jet (jet mis-identified as a photon); Z(ee); ttbar; WW; ZZ;WZ etc. • Non-collision events: Beam halo, and cosmic rays. • QCD: shower shape & isolations to get the control sample of di-photons; Use low MET region to predict bkgs in high MET region. • EW: e+gamma events (and e+gamma control sample for QCD contribution) scaled with the electron faking photon ratio (Zee for this ratio). • Beam halo, and cosmic rays: beam halo events; out-of-time events.

  8. Control Sample: QCD bkg Preliminary Shilei Zang • All MET<80GeV is contributed from QCD. • Enough QCD control events with isolations. • The MET shapes are different in low MET regionand roughly same in high MET region. • Control Sample: Both photons pass loose cuts and at least one photon fails the standard cuts. Compare shapes; control sample:(trkIso<infinite) Di-photons; 1/fb (trkIso<9GeV) 8

  9. Control Sample: QCD bkg Andrew Askew Bkg (red); Signal (blue) • Control Sample: both photon fails the standard cuts. (i.e. trkIso>9GeV for both photons) • Same conclusions as the previous slide? • Studying cluster shape for the control sample.

  10. Control Sample: EW bkg R. Stinger, B. Heyburn N2 N1 • Chowder • Track match for electron • Track un-match for photon: trkIso<5GeV (for the moment). • track match efficiency  ratio=(1-eff)/eff

  11. Control Sample: EW bkg F. Santanastasio, D. del Re, S. Rahatlou

  12. Mass variable (lower priority) Shilei Zang default a=1. mass MET mass Pt1>90; Pt2>30 Met>130 Pt1>90; Pt2>30 Pt1>90; Pt2>30 12

  13. Preliminary • Pt1>90; Pt2>30; Met>120 • 1/fb • GMSB: 57.7events (12535) • Gumbo: 5.3 events (39) • Chowder: 2.2 events (7) • Need more bkg events for bkg studies (Fastsim?)

  14. Summary • Standard cuts of di-photons can be used. • HLT validation, and Fastsim validation are finished. • Common code (Rtuple) is available. • Studies of QCD control sample and EW control sample have a good shape, and are in progress. • Improvement of photon ID is in progress. • Signal extraction, multidimensional fit, and reduction of the systematic are in progress. • Lower priority now: Beam halo studies; Mass variable; non-pointing neutralino (lifetime); … Thank you!

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