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Hasty Overview of Photon + MET Studies in the Context of GMSB

Hasty Overview of Photon + MET Studies in the Context of GMSB. Bruce Schumm Joint SUSY/UED Meeting 23 November 2010. Significant Transition: MGM to GGM. Tevatron analysis based on “Snowmass Points and Slopes” trajectory that is essentially Minimal Gauge Mediation (MGM)

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Hasty Overview of Photon + MET Studies in the Context of GMSB

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  1. Hasty Overview of Photon + MET Studies in the Context of GMSB Bruce Schumm Joint SUSY/UED Meeting 23 November 2010

  2. Significant Transition: MGM to GGM • Tevatron analysis based on “Snowmass Points and Slopes” trajectory that is essentially Minimal Gauge Mediation (MGM) • MGM ties strong (gluino) and EW (neutralino) partner scales together, and leads to very massive gluino • Tevatron analyses exploited weak production (lot of data at low energy); sets limits on neutralino mass MGM not particularly well motivated  look at Generalized Gauge Mediation (GGM) which decouples strong, EW scales Re-cast in terms of limits in Mg-M plane for each of three possible neutralino species: Bino-, Wino-, Higgsino-like

  3. Thanks to Shih/Ruderman, ArXiv 0911.4130 Production cross-section (7TeV) Bino - like Neutralino: |M1| <<  and |M1| < |M2|; M of Neultralino NLSP ~ M1, Neultralino NLSP   + Gravitino (76%) MGM trajectory No visible jet activity when Mg ~ M For Bino-like neutralino, two photons + MET is most promising but lose coverage if hadronic activity is required (jets, HT, etc.)

  4. Wino - like Neutralino: |M2|<< and |M2| < |M1| Production cross-section (7TeV) Natural for photon+lepton channel Not shown: Higgsino, which has no photonic decay, but a partial admixture might show up in photon + jet(s)

  5. Analysis Details (largely a list of items without specifics; see sharepoint(?)… not optimized yet since signal MC just becoming available) • Trigger: • EF_g10_loose period E2 and before • EF_2g15_loose after period E2 • Data streams: various (AOD, Susy D2PD, SUSY D3PD) • SUSY Good-Run-List (GRL) • Photon • Defintion: RobustTight • || < 2.37 and not in crack region • Isolation: EtCone20/Et < 0.1(see next slide) • Require two photons: E1 > 30 GeV; E2 > 20 GeV • Overlap removal • Jet cleaning, OTX, good primary vertex…

  6. Photon Isolation Requirement Fake photons (jet) Real photons (signal, QCD direct-) Fairly strong preference for ETCone/ET. Since jet backgrounds not expected to dominate, choose loose cut ETCone/ET < 0.1.

  7. MET SUSY “standard” is SimpRefFinal, but this contains no explicit photon term We will use RefFinal MET cut not yet chosen; typically would be ~100 GeV (or: use no MET cut?)

  8. BACKGROUNDS – ROUGH OUTLINE • Basic Idea: Use control samples to constrain MET shapes of various background processes. Normalize to data in control regions. • Backgrounds without instrinsic MET • Two real photons: • MET from Z  ee • One photons, one jet  photon • MET from tight/loose photon control sample • Two jet  photon • MET from loose/loose control sample? • Fit region MET < 30 GeV (?) to normalize separate contributions

  9. Composition of Photon-Loose Control Sample (Single photon)

  10. Single-photon control sample: Data vs. MC We know there are K-factor uncertainties, but we can see that jet   fakes are not horribly out of whack. Next up: di-photon control sample

  11. Backgrounds with intrinsic MET • Assumption that this is dominated by e   fakes in W, ttbar, etc. • MC suggests 85-90% of background is e  ; remainder is jet   • Control sample is e (veto if second ) • Have started with tight photon + medium electron, but are wondering if tight/tight is better (future triggers a consideration) • Derive  fake content by applying e rate measure via Z sample tag-and-probe • Still need to separate out component with intrinsic MET from that (such as Ze) without, since the Z fakes will be accounted for in the no-MET control sample

  12. e Control Sample Composition (helps to reject events with second hard photon)

  13. Electroweak contribution to the e control sample • Dominated by Z at low MET • Use to estimate background for MET about ~100 GeV Comparison of “signal” (two photons) to “control” (one electron/one photon; reject if second photon)

  14. Systematics to Consider • Event Selection Systematics • Trigger (and skim if used) • Photon identification and selection • Et scale (Et cut) • MET response (MET cut) • Isolation cut (Model dependence) • Object quality (OTX cut) • Pileup effects • Cross Section Uncertainties • Parton distributions • K Factors

  15. More Systematics to Consider • Background Systematics • Control sample statistics • low MeT normalization of QCD background • e sample • e   rate determination • Relative amount of jet   vs. direct photon in QCD background • Non e backgrounds with intrinsic MET • Luminosity Uncertainty

  16. Additional needs/opportunities • Photon efficiency from Zee? • Limit formalism (fit to MET spectrum?) • Trigger studies • Strong ISR • Other discriminating varilables (HT, , M, …) • Non-pointing photons • Wino/Higgsino-like analyses (single-photon + XXX?) • Work on reducing e rate (extra hits, B-layer outliers…) • Other ideas…

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