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Update on the Diphoton + MET Analysis

Update on the Diphoton + MET Analysis. Bruce Schumm, channeling Ben Auerbach (Argonne), Osamu Jinnouchi (Tokyo Tech), Susan Fowler (Penn) UC Santa Cruz / SCIPP 6 March 2014 SUSY General Analysis Meeting. Conference Note public in early January:

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Update on the Diphoton + MET Analysis

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  1. Update on the Diphoton + MET Analysis Bruce Schumm, channeling Ben Auerbach (Argonne), Osamu Jinnouchi (Tokyo Tech), Susan Fowler (Penn) UC Santa Cruz / SCIPP 6 March 2014 SUSY General Analysis Meeting

  2. Conference Note public in early January: Search for Supersymmetry in Diphoton Events with Large Missing Transverse Momentum in 8 TeV pp Collision Data with the ATLAS Detector ATLAS-CONF-2014-001 List of Tasks generated to move from note to paper…

  3. Analysis Strategy (lower reach of Wino-Bino limits) Also: require ET > 75 GeV for each of the two photons • Low-mass winos lead to limited • Photon ET • MET • Overall energy scale • -MET • Efficiency falls off faster than cross section rises and there is a likely lower limit on the wino mass scale • Appears to be below 300 GeV (lowest mass simulated) • We are evaluating this now for the 2012 selection

  4. WP2 observed #event UL = 8.3

  5. WP2 observed #event UL = 8.3

  6. Analysis Strategy Continued 5 fb-1 analysis required ET > 50 GeV and Not good • 1 fb-1 analysis required • ET > 25 GeV • MET > 125 GeV • These will likely place lower limits on the wino mass than those of the 8 TeV analysis (which are still being determined) • Estimate of lower wino limit for 1 fb-1 analysis underway… but can we really include that in a paper? DISCUSS

  7. MC Generation/Simulation Tasks • There were several issues to address that required more MC • Low mass wino  Extend grid from 300 GeV down to 100 GeV •  This is high cross-section/low-efficiency regime; need to work out filtering mechanism • Low mass bino  Extend explored bino mass reach down from 50 GeV to 10 GeV for all gluino, squark, and wino masses  Requires care to avoid metastable states, direct gravitino decays (our model requires decay through bino) • Nearly degenerate case for EW production (M_bino close to M_wino)  Add points with m of 25 and 10 GeV Again need to watch for pathologies • SLHA files generated; squark and gluino points submitted, wino points hopefully ready for submission soon.

  8. Analysis Tasks • Increase jet ET cut from 20 to 40 GeV (M_eff reconstruction)  very little change to anything • Evaluate pT dependence of e   fake rate •  play role in determination of EW background •  evaluated with “tag and probe” method •  No significant pTdependence observed • Check grids developed for other signatures •  DISCUSS

  9. Background Studies • Estimate H   background •  Use existing H   MC sample •  Pass through all 5 analysese •  Contributions at 10-2 level or less • Re-evaluate jet-MET uncertainty •  Inclusion of overflow bin made diphoton and control distributions much more similar •  Reduce uncertainty accordingly (small change in overall background uncertainty • Re-examine QCD/EW background overlap uncertainty •  25% of EW backgrounds do not involve an e fake •  MC truth enumeration of processes suggested they might instead be included in QCD background •  ± 25% uncertainty adopted •  Do more explicit study to determine overlap; perhaps reduce 25% uncertainty (UNDERWAY)

  10. Signal Sytematics • Include photon ID systematics correlations  Done! • Explore differences between ATLFAST and full sim •  Several point in EW have both •  differences at few percent level •  No action taken; new points in full sim but we intend to use either with impunity

  11. Signal Systematics • Include photon ID systematics correlations  Done! • Explore differences between ATLFAST and full sim •  Several point in EW have both •  differences at few percent level •  No action taken; new points in full sim but we intend to use either with impunity

  12. Interpretation/Limits • Redo gluino/bino contour (changes very slight, except extension to Mbino < 50 • Set limit in squark/bino plane, including low bino mass • Set limits in wino/bino plane, including lower limits (additional MC needed; hope to submit soon • Set limits in constrained SPS8 model (signal MC already in place) • All need to be done; awaiting completion of other steps, especially, MC simulation.

  13. Wrap-Up • Most of proposed work towards paper completed • Major focus for paper now is MC generation (low-mass bino; lower limits on wino mass • Probably will be a gap between LHC and LEP wino mass limits  can this be filled with re-consideration of 1 fb-1 analysis? • QCD/EW background overlap refinement underway (necessary?) • Look at other signal grids with our analysis? • Most of changes documented in new backup note; not yet in SVN or CDS.

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