1. Update from the Photons + MET Group Bruce Schumm UC Santa Cruz / SCIPP 11 March 2010

2. 2 Background Info Since the SUSY/ETMiss Kick-Off, group has expanded a bit Photon(s) + leptons (U. Michigan) Constraining MET with data (U. Victoria) Plus prior Photons + MET (GMSB) group DESY Liverpool Santa Cruz

3. 11 March 20103 100 pb -1 Analyses Plan to have two baseline analyses, both GMSB-inspired, but concerned about model indpendence Photon(s) plus MET –Subject of this presentation Photons(s) plus leptons plus MET –Subject of later presentation by U Michigan

4. 11 March 20104 Photons plus MET Analysis We’ve been asked to think about Baseline analysis –Possible hard/medium/soft scenario What we can do with 10 pb -1 for summer conferences –Should support progress towards baseline 100 fb -1 analysis

5. 11 March 20105 Prior Studies 10 TeV / 200 pb -1 analysis with Two photons and hard (160 GeV) MET cut (SCIPP) Two photons and NJET cut; soft MET cut (DESY) e.g. Two Photon plus MET Result

6. 11 March 20106 New Thinking I: Production and Decay Scales Very roughly, two scales in problem Production scale; heavier mass SUSY partner sets overall Pt scale of event Decay scale: NLSP (  0 ) sets scale for MET So: use two independent discriminating variables: MET HT (sum of ET of all objects in event, excluding MET) (But how independent are these really?) Production Decay

7. 11 March 20107 Baseline Analysis Proposal for Baseline Analysis Require two photons (powerful background suppression) Optimize cuts on MET and HT based on SPS8 trajectory (“analytic continuation” of GMSB1 to higher neutralino mass) Is underway and should be available soon.

8. 11 March 20108 Further Thinking II: Strong vs. Electroweak Production Initial production can be “strong” (two squarks/gluinos), “electroweak” (two gaugino), or mixed (one of each) Still two photons from final decay, but signature quite different otherwise Electroweak production dominates at 2 TeV (Tevatron)

9. 11 March 20109 Relative Percentages of the Types Breakdowns for 10k points Key: –Bin 0 = Weak –Bin 1 = Mixed –Bin 2 = Strong About ~30% for Λ=90 TeV and ~10% Λ=120 TeV Total production cross sections: –Λ=90 TeV : 0.51pb –Λ=100 TeV : 0.29 pb –Λ=110 TeV : 0.17 pb –Λ=120 TeV : 0.11 pb Strong production has effective x-section of ~11 fb for Λ=120 7 TeV SPS8 rates Weak Strong

10. 11 March 201010 HT (sum of all ET except MET) vs. MET for full GMSB Sample

11. 11 March 201011 HT (sum of all ET except MET) vs. MET for “Strong” GMSB Sample Optimal cut from MET analysis

12. 11 March 201012 HT (sum of all ET except MET) vs. MET for “Weak” GMSB Sample Optimal cut from MET analysis

13. 11 March 201013 HT vs. MET for ttbar (e  background; require one SL decay)

14. 11 March 201014 HT vs. MET for QCD (JF17, 7 TeV MC09)

15. 11 March 201015 Baseline Analysis and Strong vs. Electroweak Producion Possibility: “Hard” analysis selects strong component with low backgrounds; “Soft” analysis sensitive to weak component but with higher backgrounds Note that production was almost exclusively weak at Tevatron But: weak-sensitive is more sophisticated analysis, perhaps not for first pass…? Proposal is to start with single, “hard” analysis.

16. 11 March 201016 10 pb -1 Plans Unlikely to set new limits or discover GMSB SUSY (although strong channel is turning on, with clear signature)

17. 11 March 201017 Can we

18. 11 March 201018 Three Categories of Events Seems to be three main categories of events classified by the sparticles coming out of the hard scatter –Weak production Events with two: neutralinos, charginos, sleptons –Strong production Events with two: sqaurks or gluinos –Mixed Take one particle each from the two other categories All three types of events have different characteristics The ‘mixed’ type are basically intermediary of the two Used 7 TeV SPS8 atlfastII sample

19. 11 March 201019 Effect of Photon Selection Using the normal selection cuts for photons from past analysis (pt, isolation, etc) Looking at weak versus strong, the weak production events seem to have greater proportion of events with 2 photons Photons being lost because the strong prod. events are busier? This plus all remaining plots are using Λ=90TeV

20. 11 March 201020 Photon P T Spectrum Pt spectrum seems to have longer tail for the strong prod events –Seems to be a lot of the tail (plot needs better zoom) Though current pt cuts (or slightly higher even) shouldn’t bias us against one or the other prod mechanism

21. 11 March 201021 Missing Et Spectrum Definitely different shapes as we thought Strong production is most of the tail MET > 160 GeV cut - definitely cut out most of the weak production as was speculated

22. 11 March 201022 Number of Jets Jets (sorta random): –Et > 20 GeV –Eta < 2.5 –Removed overlap with photons + electrons (deltaR cut) Strong and weak production fairly different in terms of number of jets Mixed typed are intermediary

23. 11 March 201023 “M eff ” – no Missing Et Sum of the et of the four highest et selected jets (that weren’t removed by overlap) Double structure indeed comes from what we though it did Strong production peak is already pretty small at Λ=90 for 7 TeV

24. 11 March 201024 “M eff ” – w/ Missing Et Shifts spectrum to the right Strong production peak moves further – though that’s expected from the met distributions

25. 11 March 201025 HTHT Everything added together – nothing surprising here

26. 11 March 201026 Summary The strong and weak production mechanisms contribute as we had come to suspect There is a third intermediary type of events, but its cross section is very small Strong production component is already pretty small at Λ=90 for 7 TeV and drops off quite quickly from there No real revelations here but at least it conforms what we had suspected was going on