(Di-)Photon + MET Status and Plans for 5 fb -1 Analysis Who plans to contribute? DESY (Ehrenfeld, Wildt, Vankov) Annecy (Przysiezniak-Frey) Penn (Williams, Bradmiller-Feld) Santa Cruz (Damiani, Kim, Nielsen, Schumm) La Plata (Dova, Alonso) Tokyo (Jinnouchi) Bruce Schumm 3 Nov 2011

1 fb -1 Analysis: Thumbnail Sketch (First-order) signal selection straightforward:  2 tight isolated photons with E T  25 GeV E T miss  125 GeV  Optimization based only on E T miss cut value. Compare to CMS analysis: At least 2 isolated photons withE T  45,30 GeV E T miss  100 GeV At least one jet with E T  30 GeV

ATLASCMS # obs (exp)5 (4.1)0 (1.5) Lum (fb -1 ) Obs limit (fb)2627 Exp limit (fb)2333 Much time spent in deconstructing this difference, but at the end of the day, it all comes down to expected limit. How could these numbers be consistent?

The answer to the conundrum lies in the acceptance*efficiency: e.g. at (m g,m B,m q ) = (880,375,1520) ATLAS 27% CMS 12% But let’s look at backgrounds… “Instrumental” “Genuine”

But CMS made their cut at 100 GeV; for that cut backgroundsCMSATLAS Instrumental Genuine TOTAL Our estimated backgrounds:  CMS significantly reduced the “genuine” component (jet requirement? e  gamma fake rate?) at expense of efficiency.

In addition, examination of our high-P T events suggested e   fakes do indeed dominate alignment of E T Miss with photon This motivates Studies to reduce backgrounds Use of additional discriminating variables Since we have a little time, we’ve tried to open things up a bit (but we are now beginning to refocus on optimization for final event selection)

Penn: Look at isolation, conversion category, pixel hits

0 conversion 2 conversions 1 conversion 0 conversion 1 conversion 2 conversions

So where do we go from here? Penn/La Plata: Explore isolation w/ W sample; devise pragmatic suggestion for optimization: E T Cone_20,30,40? Cut energy? Energy-dependent cuts? Leading vs. sub-leading? La Plata/UCSC: Discrimination of other observables: Separate conversions categories, pixel hits for conversions, E T Miss (scaled?), Photon-E T Miss , Photon E T, Photon-ETMiss transverse mass, M eff /H T, jet activity DESY: Contamination in QCD control sample (W, signal…)

6 Oct 2011SUSY Photon Meeting11 Bino-Like Grid Points 2-d Gluino vs Bino grid – Gluino masses: 800, 850, 900, 950, 1000, 1050, 1100, 1200 – Bino masses: 50, 100, 150, 300, 450, …, mgl – 20, mgl – points total – 5000 events per point 2-d Squark vs Bino grid – Mainly care about this grid to measure acceptance differences with respect to the gluino-bino grid. – Same basic structure of points as above. Status: Submitted; awaiting processing.

Rough Calendar (Feedback?) Preliminary studies (isolation, discriminating variables, QCD control sample) finish this week Optimization over next two weeks (next week through 21-Nov?) Un-blind (Through 1-Dec?) Systematics (Through 15-Dec?) What should target for support note be?

Photon + X + E T Miss Starting to ask: what should “X” be? CMS: X = 3 jets above 30 GeV Have started to look at signal, background for single tight photon selection (MC; no trigger selection yet) Signal: 800 GeV gluino, 400 GeV Bino, all else at ~ 

250 fb -1 of signal

1.8 fb -1 of W 

6.8x10 -5 fb -1 of QCD_J2

1.2 fb -1 of QCD_J5

Photon + X + E T Miss Next Steps Look at full 1 fb -1 (5fb -1 ?) loose-tight E T Miss distributions to gauge QCD backgrounds from data. Look at W+jets and ttbar for other possible contributions To me, backgrounds look a little less daunting than I had feared (but this is all MC, and only a partial sampling so far)