Diphoton + MET Analysis Update

1. Diphoton + MET Analysis Update Bruce Schumm UC Santa Cruz / SCIPP 03 July 2013 Editorial Board Meeting

2. [From Philip’s 17 June email summarizing the 14 June Ed Board meeting]:  • Still missing: test uniformity of acceptance of the chosen cuts by fixing the optimized cuts, and then plotting eff and A over all grids. Conclusion on optimization: If there are no artificial features visible in the abovementioned plots, we treat the optimization as final. • FOLLOW UP: Plots had been made some time ago; shown in 28 June Ed Board meeting. • Response from Ed Board: • Questions to look at: • convince yourselves that even for the lowest acceptance you still have sensitivity in at least one of the signal regions (based on modified asimov, or real limit machine, or whatever) • Will happen as we study expected limits over parameter space • add a few explanatory plots to the note showing what exactly reduces your acceptance for low bino mass in SP, and low Wino mass in WP • Still need to do • make sure that the artificial effects in the grid, like the missing triangle for mbino=450 to 600 in the WP grid, does not cause a gap in the exclusion • Again, should become clear as we study expected limits over parameter space

3. [From Philip’s 17 June email summarizing the 14 June Ed Board meeting]:     Question: Is it OK to leave DeltaPhi^jet_min = 0.0 ? Looks like, is included in BG control Conclusion: Look at DeltaPhi plot in QCD control region whether this is well described, explain how it is controlled in the control regions, if no strange features: OK FOLLOW UP: Plots made; agreement not so good for  between MET and jet. • Response from Ed Board • make sure that the bin at deltaPhi=100 is included in the normalization • Needs to be done • study the effect of making the cut.not making the cut on the BG estimate, assign systematics if necessary (show that again, I guess) • Removing jetMET cut, WP2 QCD background estimate increases from 0.90 to 1.70 (1.52 for LocHadTopo). But note that some increase is expected since a cut is removed

4. [From 7 June email]      • Why document QCDg if not usebale acc. to page 3 with MetRefFinal? Conclusion: streamine the way it is presented in the note. Include QCDg everywhere in the plots examining the MET performance, but *just* remove the QCDg samples from the BG control tables which are argued to be unusable based on the first set of plots. With clear arguments of what to use and what not, based on the MET performance plots • Note updated. • [Ed Board should] Review the argument concerning the QCD background estimates in the note. Led to Ed-board follow up: • add a very conservative systematics on the final QCD estimate in the following way: • shape: relative difference between g+Iso and tg in the signal region • normalizaton: largest relative difference between g+Iso and tg or gg and QCDtg (whatever is larger) in the control region (MET<100) • Some further discussion (next pages…)

5. add a very conservative systematics on the final QCD estimate in the following way: • shape: relative difference between g+Iso and tg in the signal region • normalizaton: largest relative difference between g+Iso and tg or gg and QCDtg (whatever is larger) in the control region (MET<100) Ratios relative to QCDtg+iso • Some thoughts: • QCDg+iso doesn’t have enough stats. Only QCDg does but it overestimates • “Shape” uncertainty (constraining the MET tail) from LocHadTopo • Both QCDtg and QCDg good estimators • Actual background slightly higher • Stringent upper bound • Not sure how to derive “normalization” uncertainty from studying other control samples • Could instead look at normalization vs. control region bounds (likely small)

6. More plots: QCDxx/gg for MET < 100 ~50% changes in ratios as control region is chosen (any slice of MET as long as MET < 100)

7. [From Philip’s summary of the 26 June Ed Board meeting] • sideband studies: Very important study, I think! • the high-HT region generally looks fine. Maybe have a closer look at the one single event at HT>1800 on page 22, where you would expect none. • Not yet done. • For MetRefFinal, the chosen MET estimator, the low HT region looks strange. This is probably highly correlated with the overshoot at low MET in the plot on page 4. Since the plot on page 4 clearly shows that the MET agreement for the QCD estimate gets better above the region of 60<MET<100 shown here, this is probably nothing to worry about too much. But we should see the sideband study including MET systematics to be sure (see 'Ratio plots on QCD estimators' above). • Need to re-do sideband study with QCDg+iso (statistics)? • It also could be that the QCD estimate from data is polluted by EWK in this very low MET area (not expected at higher MET in the signal region). Try to roughly estimate that (from MC?) and put it in the sideband estimate. Including these updates, if the sideband comparison loks good, I would have a lot of faith in the total BG estimate. • Probably OK – EWK component is included and is estimated from data, which should be more reliable than MC

10. Explain calculation of the 'observed' K factor and its                uncertainty in the note and check the result with SM                group and their Wgg analysis Had already been done. SM analysis apparently not yet mature. Separate limit for ttbar? Simplified models?                The suggestion is to take the GMSB inspired signal MC                grid and separate the MC at each point into pure qq, qt                and tt samples, then make simplified model limit result                plots using exactly the same selections, BG systematics                and BG estimation as for the combined result. - Other Action items:     - answer all remaining question on CDS     - upload new version of the note     - ratio plots for plots on page 3 and 4 (Done)    - check ctau reach of the analysis?     - look into MET>100 pure MI selection?     - look into SPS8 point Other than the ratio plots, none of these has been attacked.