1 / 16

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)

gerard
Télécharger la présentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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…

More Related