1 / 20

Update on Backgrounds to the Diphoton + MET Analysis

Update on Backgrounds to the Diphoton + MET Analysis. Bruce Schumm, for the group UC Santa Cruz / SCIPP 30 July 2013 Diphoton+MET Ed Board Meeting. Primary changes since last we met:

eliot
Télécharger la présentation

Update on Backgrounds to the Diphoton + MET Analysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Update on Backgrounds to the Diphoton + MET Analysis Bruce Schumm, for the group UC Santa Cruz / SCIPP 30 July 2013 Diphoton+MET Ed Board Meeting

  2. Primary changes since last we met: • Apply Δφjet to all five SRs (had just been model-independent and low-mass-bino weak production SRs). Recalculate all backgrounds • Irreducible background signal contamination systematic • Updated sideband studies • NOTE: • In version 1.1, everything is updated with Δφjet cut except • Control sample comparisons (slide coming…) • Extrapolation studies (but changes are miniscule) • Start with Electroweak Backgrounds…

  3. OLD (bold entries are signal regions) NEW No change to bold entries.

  4. Irreducible Background. As before look at lγγ events Expect 6.5 Wγγ events and 0.9 other Events (7.4 total) Observe 7 events. Wγγ K-factor assumption confirmed Stat error is sqrt(7)/(7-0.9) ~ 40%

  5. Proposed diphoton_MET Signal Regions

  6. But also looked at possible signal contamination in the Wγγ control region Adopt 3.0 as systematic uncertainty: 3.0/6.5 ~ 45%

  7. Irreducible backgrounds before Δφjet cut Irreducible backgrounds after Δφjet cut and including new signal contamination systematic

  8. QCD backgrounds: basis is ABCD method (this is for nominal “QCDtg-noiso” control sample A B C D A __ C * D = B

  9. As discussed, with or without Δφjet cut, QCDtg-noiso is control sample of choice for better or worse ETmiss

  10. Use ABCD method in MET sideband, as a function of HT. Also include EW and irreducible backgrounds so that we can compare with data Without Δφjet cut Overestimates observed tight-tight counts! With Δφjet cut Uncertainty from comparison with QCDtg+iso, statistics… in first three HT bins they are 4.3, 3.7, and 1.6 events; 7.1 events overall  1.9σ

  11. So what are the QCD background estimates and uncertainties? Direct estimates with statistical error Vary the normalization (A/B) region

  12. If you assume “gg” is actual background distribution, this Gives a ~50% uncertainty in the QCD background (conservative, but OK for now…?)

  13. SP1 Extrapolation

  14. SP1 QCD Background Estimate Direct: < 0.11 Extrapolations (ignoring upper limits in two highest HT bins): 0.00, 0.15 Both suggest background is very close to 0 and unlikely, at 68% CL, to be greater than 0.2 NQCDSP1 = 0.1 +- 0.1 Again, subsumes uncertainties from normalization range, Δφ

  15. SP2 Extrapolation Nominal (direct) estimate 68% CL

  16. SP2 QCD Background Estimate Direct: 0.33 +- 0.33 Extrapolations: 0.10, 0.17, 0.23 Direct result not so constraining, but extrapolations suggest background is close to 0 and unlikely, at 68% CL, to be greater than 0.3 NQCDSP1 = 0.15 +- 0.15 Again, subsumes uncertainties from normalization range, Δφ

  17. WP1 QCD Background Estimate Direct: 0.29 +- 0.21 Normalization region change: 45% Δφ uncertainty: 50% WP1 estimate: 0.29 +- 0.29 events Low HT issues from sidebands? Uncertainty is already 100%...

  18. WP2 QCD Background Estimate Direct: 0.89 +- 0.36 Normalization region change: 30% Δφ uncertainty: 50% WP2 estimate: 0.90 +- 0.60 events Low HT issues from sidebands? Again, uncertainty is already large (67%).

  19. MIS QCD Background Estimate Direct: 0.73 +- 0.28 Normalization region change: 35% Δφ uncertainty: 50% WP1 estimate: 0.73 +- 0.53 events Low HT issues from sidebands? Again, uncertainty is already large (73%).

  20. Signal Region Total Background Estimates

More Related