Photon(s) + MET Analyses

1. Photon(s) + MET Analyses Bruce Schumm UC Santa Cruz / SCIPP 16 April 2013 ATLAS SUSY Workshop Amsterdam, NE

2. Motivation: GMSB and the Neutralino NLSP • GMSB breaks SUSY via intermediate-scale messenger interactions • Naturally protects SM flavor symmetry • LSP is gravitino “Minimal” GMSB • Over much of parameter space NLSP is short-lived neutralino • If NLSP is bino admixture, 10  G likely • Pure bino  B(10 G)  cos2W  78% • Prompt diphoton + ETmiss signature • Prompt photon + Njets + ETmiss signature

3. Prior Analysis: Diphoton + MET A: Strong production, heavy bino B: Strong production, light bino C: Electroweak production For strong production, high total-energy cut gives ~background-free analysis EW production Strong production

4. 8 TeV Analysis: Diphoton + MET For 2012 (8 TeV) Data: Augment “constrained” weak production SPS8 model with wino/bino grid Bino = 10 Wino = degenerate triplet 1 and 20 Production through 1 20 and 1+ 1- “SPS8” Trajectory Resulting signal regions Signal region optimization points “Model-independent” selection  MET cut for which QCD, EW background are about the same. Low-mass, high-mass bino for Strong and EW production

5. Issue for Photon(s) + MET Analyses: What MET? • Significant changes for p1328 relative to p1181 • Use gamma-gamma MC as proxy for signal (can look at high MET) • EG10NoTauPhotonLoose designed for photon analyses; performs worse in p1328 • “Vanilla” MetRefFinal does well

6. Control samples for MetRefFinal “g” is control photon (loose but not tight); can be isolated or not “t” is isolated tight photon “QCDtg” is nominal diphoton control sample  Good agreement w/ signal MET, especially QCDtg

7. Challenges: “Irreducible” W Background • Sizeable for EW production and “model independent” selections • Constrain with data looking at (e,) events 125 < MET < 250 Expect: ~1.5 Observe: 0 Constrains K-factor (currently assumed to be 33) 50 < MET < 125 Expected signal (MC) 125 < MET < 250

8. CMS diphoton+MET with 4 fb-1 at 8 TeV • CMS diphoton analysis: • Employs no “overall energy scale” observable (HT, Meff) • Single analysis similar to ATLAS “MIS” signal region • Look at strong production only

9. Single Photon + MET Analysis • Motivation: Diphoton analysis may not be sensitive if • Neutralino is not NLSP (no photons; not for this session!) • Neutralino is the NLSP but is not purely bino • GMSB Neutralino NLSP Phenomenology • Bino-like  diphoton final state • Wino-like admixture  photon + lepton • Higgsino-like admixture, <0  photon + bjets • Higgsino-like admixture, >0  photon + jets Single Photon + MET analysis covers this final, missing signature

10. Single-Photon + MET Signal Regions • Minimize model dependence by minimizing Njet requirement • RT2 is fraction of total visible energy in two leading jets • CMS single- analysis • Photon ET > 80 GeV • 2 jets with pT > 30 GeV • HT > 450 GeV • MET in bins, but sensitivity arises for MET > 250 • Set limit of mgluino > 1125 GeV for bino-like neutralino (4 fb-1 at 8 TeV)

11. Photon + MET Challenges / Next Steps Devising grid was significant development (tune gluino, neutralino BFs and lifetimes) but is now being submitted for generation. Next steps: understand backgrounds challenges, e.g.

12. Conclusions and Outlook • For 8 TeV data, significant new model space has been introduced • Weak production (decoupled strong partners) limits with diphoton analysis (bino-like neutralino) • GMSB scenario with photon + jet signature • Plan is summary paper with all four photon(s) + MET analysis, covering full range of neutralino NLSP possibilities, plus electroweak production for bino- and wino-like NLSP • Distinction between pointing, non-pointing signatures is somewhat arbitrary and artificial  Combine into unified analysis for 2015 data?