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Progress and Plans for Diphoton + MET Analysis

This update discusses the progress and plans for the analysis of events with diphoton signatures and missing transverse energy (MET). Topics include optimization and control region studies, background estimation and systematics evaluation, signal and background theory systematics, and validation regions. Additionally, progress on the analysis of the signal and backgrounds is reported, including signal grid optimization, estimation of fake rates for electrons and jets, and background estimation using the ABCD method. Plans for future work, such as validation studies and unblinding, are also outlined.

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Progress and Plans for Diphoton + MET Analysis

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  1. Diphoton+MET: Update on Plans and Progress Bruce Schumm SCIPP On Behalf of the Photon+X Working Group La Plata, LPNHE Paris, Milano, Tokyo Tech, UCSC 21 January 2016

  2. But First: Photon + jets: status and next steps • Optimization and Control Regions studies (including fits and normalization factors) are done and results are documented in the backup note. • Data driven background estimates for jets faking photon will be based on the proposed ABCD method, but need to be adapted to the photon+jets scenario with the corresponding selection (contribution is very small in SR anyways). • Systematics • Tools for systematics concerning object identification and calibration are in place in SUSYTools but the corresponding uncertainties still need to be evaluated. • Signal theory systematics are already evaluated. • Background theory systematics need to be evaluated. • Validation Regions are in place, need to run and have a preliminary look at the distributions (MC based backgrounds and no systematics yet). Back to Diphotons… 2

  3. Recent Progress to be Reported Signal Grid Optimization EW (e  ) background • e   fake rate estimation QCD ( and j  ) backgrounds Irreducible backgrounds • W control sample • Z cross section scale factor Plans

  4. Comparison of kinematics between old and new (1300,1290) point checks out Resubmit 12 failed points very soon…

  5. New: minimum background uncertainty of b = 0.2 events

  6. Optimization: (mgluino,mbino) = (1500,100)

  7. Optimization: (mgluino,mbino) = (1500,1300)

  8. Optimization Results Results suggest single SR with the following selection cuts: • pT > 75 GeV • (jet,MET) > 0.5 • Etmiss > 175 GeV • Meff > 1500 GeV Relative to the 8 TeV analysis, we have • Introduced background uncertainty in the optimization • Have x10 less luminosity This seems to lessen emphasis on ultra-low background, lead to optimization point that is very inclusive of the signal, de-emphasizing the differences between the two focus points.

  9. Background Estimation • EW (e  ) Background • e   fake rate estimation • QCD (jet  ) Background • Irreducible Background • Wgg (via control sample) • Zgg (via Sherpa normalized to Bozzi et al)

  10. e   Fake Rate Slightly new approach: no distinction between “tag” and “probe”; instead, just look at ee and e pairs within the Z mass region Consider both electron and photon objects down to 25 GeV ee e

  11. e   Fake Rate Continued • Form 2D grids in , pT • Two entries for ee events; only photon for e events • Ratio of grids gives fake rate as a function of , pT • Have required e+e- to be back-to-back; may limit pT reach of study • Are looking into removing this requirement

  12. QCD Background Estimate • Old approach: • “Data” in above plot is pseudophoton control sample •  is from MC • Use MET shape of pseudophoton sample, after subtracting off  contribution, to estimate QCD background

  13. New Approach: “ABCD” Method • Real diphoton background from  MC • Jet   contribution from date-driven fake factor via “ABCD” method • Combination normalized in low-MET region Pseudo-photon selection from monophoton analysis Fake factor definitions

  14. Jet   Fake Factor Fake-factor give by ratio of isolated to anti-isolated pseudo-photons In Progress

  15. W Control Sample

  16. W Control Sample

  17. Z Background

  18. Z Background

  19. Summary/Outlook Signal Grid, optimization essentially done  Single SR for the 2015 analysis EW (e  ) background: Almost done; e   fake rate measurement being refined QCD ( and j  ) backgrounds: Objects defined and final studies underway Irreducible backgrounds • W control sample defined • Z cross section scale factor determination almost complete Still Needed: Validation study (e.g. 100 < Etmiss < 150) Then UNBLINDING (backup note being developed in parallel with analysis)

  20. Monophoton Pseudophoton Def’n

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