DiPhoton + MET: Towards Unblinding of the 5 fb-1 Analysis Bruce Schumm 20 Feb 2012 Reminder about 1 fb-1 analysis New strategy: A B C analyses Optimization MET Blues Background estimates Request for unblinding of A, B analyses only

1 fb-1 Analysis: Thumbnail Sketch (First-order) signal selection straightforward:  2 tight isolated photons with ET  25 GeV ETmiss  125 GeV Optimization based only on ETmiss cut value Optimization geared towards high-mass Gluino for broad range of bino masses (50 GeV to Mgluino)

Also: Limit of  > 145 TeV set on SPS8 SUSY Breaking scale Analysis background-limited; sparticle cross section goes as ~M-9  reoptimize!

Analysis Improvements Overlap Criteria - Reverse /e overlap criterion (have medium e kill ) - e  fake rate goes from 0.049-0.168 to 0.025-0.075 - 13% signal efficiency loss Conversion pixel requirements - Conversion tracks can have no pixel hits - e  backgrounds reduced by 43% (42% for events with one conversion; 61% for events with two conversions) Conversion categories - Division into three conversion categories suggested - No benefit if background is ~0

Optimization: General Principles Two scales characterize GMSB production/decay Missing energy (mostly bino mass; also bino boost)  MET Total energy, including photons (sparticle mass)  HT Analysis A: High-mass sparticle, high-mass bino Large MET, moderate HT Analysis B: High-mass sparticle, low-mass bino Moderate MET, large HT Analysis C: SPS8 (direct gaugino production; sparticles too heavy) Moderate-to-large MET; NO HT (most like 1 fb-1 analysis) Also: 1 fb-1 backgrounds observed to have photons close to MET   (photon to MET) cut explored for A,B,C analsyes

Photon Et Optimization (1 fb-1 Analysis) Helenka Choose Cut of 50/50

Full Optimization of A, B, C Points Dan Optimization strategies: All use photon ET > 50 GeV. A: ETmiss, HT, and  Use GGM (Mg,MB) = (900,800) B: ETmiss, HT (signal  too small) Use GGM (900,50) C: ETmiss,  (low mass scale in production so no HT) Use SPS8; =170 TeV

C

Optimization of A, B, C Points: Results Optimization results: All use photon ET > 50 GeV. Figure of merit rather flat in   use either 0.5 or no cut Drop unjustified significant digits Target Model ETmiss HT  A (900,800) 200 600 0.5 B (900,50) 100 1100 --- C SPS8 170 125

MET Issues ETmiss Glossary: Martin, Dan, Helenka MET_LocHadTopo Local Hadronic calibration applied to all topo clusters MET_RefFinal Based off of objects Local Hadronic calibration used for jet objects MET_SimplifiedRefFinal Based off of objects (Tight photons w/ pT>20 GeV used) EMJES calibration used for jet object Modified version of SimpRefFinal Based off of objects (Loose photons w/ pT>20 GeV used) EMJES calibration used for jet objects Doesn’t exist on D3PD ETmiss Glossary: LocHadTopo: Used for prior diphoton+MET analyses; not directly ATLAS-supported Simplified MetRefFinal: SUSY-group recommended (reconstruct ETmiss from separately-treated objects) MetRefFinal: ATLAS (but non SUSY) supported; available on SUSY D3PDs though. (Use jets with local hadronic calibration) _ Not usable for 5fb-1 analysis; explore for future.

SimpMetRefFinal: Initial “Photon Fix”

Sample used: +jet MC

Background: Definition of “QCD” Control Samples We model the ETmiss distribution of selected events with no intrinsic missing energy via two control samples: QCDg and QCDgg. A “control photon” satisfies the loose, but not the tight, selection requirement for two shower quantities: the shower shape in the shower core {fracs1} and the shower width {weta1} in the first sampling of the electromagnetic calorimeter. QCDg has one such control photon; QCDgg has two.

LocHadTopo

!!  Must also correct loose photons! Simplified MetRefFinal !!  Must also correct loose photons!

QCDg, QCDgg, and gg – MET_SimpRefFinal No resemblance of control sample eTmiss shape to that of the signal 2/16/2012 20

QCDg, QCDgg, and gg – MET_LocHadTopo N.B.: Studies with +Njets MC suggest high-ETmiss tails a bit larger for SimpMetRefFinal  Propose to use LocHadTopo for ETmiss 2/16/2012 21

BACKGROUNDS E- Control Sample QCDg Control Sample (DESY) (Penn) Overlap ? (DESY) Missed? (SCIPP)

EW Background from e- control sample Brig, Jack N.B.: “Signal” is e-

Scale factors from Ze/Zee Multiply these by “signal” numbers on previous page

Pseudo-photon control sample (Peter, Martin) SIGNAL BLINDED FOR MET > 100 GEV QCDg distribution provides shape and tails scale to signal (gamma-gamma) in low-MET region (ETmiss<20 GeV) SIGNAL BLINDED FOR MET > 100 GEV SIGNAL BLINDED FOR MET > 100 GEV

Cross-check with MET distribution from Zee (background real ?)

No QCDg above 100 GeV  Less than 1 event at 95% CL

Overlap Between QCDg and EW backgrounds Martin

Missed Backgrounds (?) Dan Since our “QCD” backgrounds are estimated by normalizing control samples (QCDg, Zee) to low-MET signal, they should be comprehensively accounted for “EW” (W,top) backgrounds estimated via e- control sample  Assumes all W,top contributions have at least one e fake Is this true? If not, what is character of the “missed” component? Might the “missed” component in fact be incorporated into the QCD control sample (pseudo-photon) estimate?

According to MC, what fraction of EW background is due to e fakes?

Of the 25% that is “missed” No e With e  +  18.9 0.0  + jet 47.5 5.0  +  3.0 2.9  + W l 22.9 18.9% + 47.5% = 66.4%  2/3 is expected to be reflected in the pseudo-photon sample This 2/3 may well be the source of the “EW-contamination” in the pseudo-photon sample (cross-check underway This component is neither missed nor double-counted!  Add “QCD” and “EW” backgrounds linearly (values and errors)

Background Summary QCD EW TOT A 0.10  0.10 0.03  0.03 0.13  0.13 B 0+0.38-0.0 0.03+0.41-0.03 C 0.7  ? 1.2  ? 1.9  ? 1 fb-1 0.8  0.7 3.1  1.5 4.1  1.7* *Includes a 0.2 event contribution from “irreducible” backgrounds (two real photons) that are negligible in A and B regions; needs to be check for C

A word on the 5 fb-1 reach (not fully-optimal analyses) ggm_900_800   -> LL: 142.4, sig: 16.9, #S: 21.3, #B 0.01 ggm_1000_800 -> LL: 39.8, sig: 8.9, #S: 7.1, #B 0.01 ggm_1100_800 -> LL: 10.8, sig: 4.7, #S: 2.4, #B 0.01 ggm_1200_800 -> LL: 3.4, sig: 2.6, #S: 0.9, #B 0.01 C: sps8_170 -> LL: 22.2, sig: 6.7, #S: 11.9, #B 0.9 sps8_180 -> LL: 14.5, sig: 5.4, #S: 8.9, #B 0.9 sps8_200 -> LL: 6.6, sig: 3.6, #S: 5.3, #B 0.9 sps8_220 -> LL: 2.7, sig: 2.3, #S: 3.0, #B 0.9 sps8_240 -> LL: 1.2, sig: 1.5, #S: 1.8, #B 0.9 B: ggm_900_50   -> LL: 45.1, sig: 9.5, #S: 10.3, #B 0.05 ggm_1000_50 -> LL: 13.6, sig: 5.2, #S: 4.0, #B 0.05 ggm_1100_50 -> LL: 2.7, sig: 2.3, #S: 1.2, #B 0.05 ggm_1200_50 -> LL: 0.4, sig: 0.85, #S: 0.3, #B 0.05 Limits for 1 fb-1 about 820 GeV for analysis-A-like scenario and ~145 TeV for SPS8 trajectory

Fire and Brimstone Verbatim 2011 analysis  150-200 GeV increase in limits 2012 analysis improvements  250-400 GeV increase CMS did better than ATLAS with 1 fb-1 because of More favorable interpretation of GGM model Luck but per fb-1, our analysis was more sensitive Dark matter, light Higgs(?)  SUSY (??) Possibility never greater; if something is there, don’t want to miss it! Critical to unblind right away.

BACKUP

Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP GamNp1 diphoton sel LocHadTopo One extra event for MET>100GeV MeanRefFinal  MeanLocHadTopo RefFinalSimpSUSY Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP 42

Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP GamNp2 diphoton sel LocHadTopo One extra event for MET>90GeV MeanRefFinal  MeanLocHadTopo RefFinalSimpSUSY Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP 43

Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP GamNp3 diphoton sel LocHadTopo One extra event for MET110 GeV MeanRefFinal  MeanLocHadTopo RefFinalSimpSUSY Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP 44

Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP GamNp4 diphoton sel LocHadTopo MeanLocHadTopo  MeanRefFinal Both have event for MET200GeV RefFinalSimpSUSY Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP 45

Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP GamNp5 diphoton sel MeanLocHadTopo  MeanRefFinal LocHadTopo Few extra events for MET80GeV RefFinalSimpSUSY Diphoton+MET meeting - 09.02.2012 - Helenka Przysiezniak / LAPP 46

QCDg, QCDgg, and gg – MET_RefFinal 2/16/2012 47