+ + inclusive search for susy with photons and etmiss final states helen hayward on behalf of the...
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Inclusive search for SUSY with photons and EtMiss final statesHelen Hayward on behalf of the SUSY-Pho group
Dan Damiani, Wolfgang Ehrenfeld, Helen Hayward,
Osamu Jinnouchi, Andy Kuhl, Jovan Mitrevski, Jason
Nielsen, Bruce Schumm, Peter Vankov, Martin Wildt, Helenka Przysiezniak Frey,
Francisco Alonso, Tere Dova
+Introduction
GMSB model: LSP is a gravitino minimal GMSB, should now be competitive Tevatron limits set on
SPS8 plane General Gauge Mediation (GGM)
Universal Extra Dimensions Single UED , R~1TeV-1
Lightest Kaluza-Klein particle γ* γ*->γG
We look for γγ+X+MET
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Search for diphoton events with large MET
Main Backgrounds QCD with instrumental MET W/ttbar events where electrons fake
photons
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+2010 : SUBMITTED !!!
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+Selection
Require two selected photons in the event.
Currently implemented cuts: EF_2g20_loose pT > 25 GeV – change comes from the trigger. PhotonTightAR |η| < 1.81 Pass the bad cluster OQ bits Etcone20_corrected < 5 GeV
Pt and NPV corrected official photon cleaning cuts
We use 10 ns cut for all photons (and electrons)
Updated 2011 egamma energy rescaling
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+Other Selections All other objects using the default SUSY
selections.
Lar hole We are currently using SUSY
nominal veto for jets with pT>40GeV inefficient for our signal
We will implement the “smart veto” Technical question of how to weight
MC for different periods. (if any unforeseen problems we will
stick to nominal veto)
GRL: data11_7TeV.periodAllYear_DetStatu
s-v18-pro08-04_CoolRunQuery-00-03-98_Susy_ph_met.xml (will update to -05)
Requires good photon and electron triggers
Requires good photons, leptons, jets,MET
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Overlap removal: Unchanged from last year. Selected photons kill electrons if
dR of the clusters < 0.01. Photon-jet overlap: like SUSY
standard for electrons.
Etmiss: MET_LocHadTopo + muon
corrections > 125 GeV. Unchanged from previous
analysis. Photon terms in MET_RefFinal
are working better, but we still see problems with most converted photons (get treated as jets) – hopefully to be fixed in future reprocessing.
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+Cut Optimization – Photon eta
2010 used photon eta 1.81 Egamma recommendation due to MC/data discrepancy for
forward regions.
Optimisation study demonstrates cut is still good for good for 2011 Optimise using best s2/b =>η<1.81
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γη QCD EWK Total UED: 1/R = 1300
GGM:900/200
GGM:900/800
Raw S2/B Raw S2/B Raw S2/B
2.37 2.59 2.16 4.75 2.7 1.53 3.32 2.32 5.47 6.3
1.81 1.79 1.79 3.69 2.51 1.71 3.02 2.47 5.00 6.78
1.37 1.28 1.28 3.06 2.28 1.7 2.76 2.49 4.49 6.59
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+Data Driven BG estimate I
Understanding the QCD control sample normalization issues
Understanding the QCD control sample shape issue (two-photon versus one-photon control sample)
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Estimate background from dijet,γ-jet, γγ
Model with QCD control sample: Define anti tight photon as a loose
isEM photon which fails some of the tight isEM requirements.
This control sample models the diphoton MET distribution very well at low MET
Development expected (~ 1-week):
Small study to understand if any W contamination in this control sample and how to remove if present
Small study to improve understanding of QCD control sample
+Data Driven BG estimate II To estimate BG from genuine
MET sources Electron-Photon control sample
Scale by electron->photon fake rate
Subtract QCD/Z->ee contamination by using QCD template (the blue histogram in figure) Difference is estimate of W
and Ttbar contributions
MC templates are scaled to data for 40<MET<125 GeV
Need to add Wgamma MC samples to this plot ~ few days
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2010:Cone20/Et<0.12011:EtCone20_cor<5GeV
+BG results
QCD template is normalised to the diphoton distribution for MET< 20 GeV W/ttbar entries in 1st bin are
artifact of this scaling.
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DiJet,PhoJet,PhoPho BG : Predicted background above 125 GeV = 2.73
+/- 0.86 (stat) +/-0.59(template shape) +/- 0.088(template scale)
GenuineMet BG : Predicted background above 125 GeV = 2.87
+/- 1.16(stat) +/- 0.28(MC extrapolation) +/- 0.017(template for Z/QCD) +/- 0.29(error on scale factor)
QCD+EWK = 5.6 +/- 1.3(stat) +/- 0.7(sys)
Zgg=0.12+/-0.014(stat)
Wgg=0.019+/-0.009(stat)
Total = 5.8+/-1.3(stat)+/-0.7(sys)
+Non collision BG
Cosmics: Use L1_EM3_EMPTY triggers to determine the rate of tight
diphotons per unit time per bunch in cosmic events. Assumed to pass the primary vertex cut by being overlaid
with a minbias event. Background demonstrated to negligible in 2010 Estimate for 2011 due < 1 week
Beam background Use unpaired bunches <2 weeks.
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+Systematic errors on signal MC
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Source of Uncertainty
Uncertainty
GGM UED
Lumi 3.7%
Trigger ...
10%...
Photon Identification
Photon Isolation
Pileup
MET 3.7%* 1.1%*
Signal MC stats
7.6%* 5.4%*
PDF and scale
10-48% -
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*2010 values still used. Updates expected within a week
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+List of Egamma Systematics I
Trigger Now have new systematics based on the bootstrap method.
An uncertainty of 0.6% is assigned based on the difference in the efficiency measured in data and MC
The efficiency measured in data is 100+0-0.38%. Because fakes also get triggered, an uncertainty of 0.6% is
assigned based on the 99.4% efficiency calculated for JF17 and JF35 samples that have offline photons. To be repeated on our MC samples.
Isolation use egamma prescribed systematics for the isolation:
apply shifts separately to pt and nPV corrections and treat the two uncertainties as uncorrelated. ETA: end of the week.
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+List of Egamma Systematics II
Identification Use official egamma fudge factors. These have two uncertainties: those
associated with the method itself, and those associated with imperfections in measuring the FFs, i.e. the background contamination. For the former, we reweigh the parametrized uncertainty that was given in the SM γγ note. For the background contamination we vary the FF sets. ETA: end of the week. Lastly, we might try extrapolation again, but that was negligible last year
Material Use same method as used for GGM in 2010 analysis: reweigh the
parametrized uncertainty that was given in the SM γγ note. ETA: end of the week
Pile up Expected systematic to be smaller than 2010 due to reweighting
technique Use method prescribed in H->γγ note
“Efficiency versus μ. The effect of the pile-up is estimated looking at the variation of the isEM tight efficiency as a function of μ (the average interactions per beam crossing) and a ±2% uncertainty is assigned per photon.”
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+Preliminary PDF and scale errors
values in Scale/PDF/SUM are relative value against the NLO sigma. e.g. at Mgl=1000GeV, the error is 38.9%.
Scale is estimated by changing the Factorization/Normalization scales by x1/2 and x2,
PDF errors (90% CL) are translated to 68% by dividing them by 1.645.
Scale/PDF are the average of the two calculations (i.e. a half and twice in scales for Scale, +/- error PDF sets for PDF.)
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Mgluino LO (pb) NLO (pb) K-factor Scale PDF SUM√(scale2+pdf2)
400 4.99 10 2 0.16 0.116 0.197
500 0.994 2.17 2.18 0.168 0.147 0.223
600 0.234 0.561 2.4 0.176 0.176 0.249
650 0.119 0.299 2.51 0.181 0.193 0.265
700 0.0614 0.163 2.65 0.181 0.207 0.275
800 0.01730 0.0512 2.96 0.192 0.247 0.313
900 0.00510 0.0171 3.35 0.199 0.288 0.350
1000 0.00156 0.00596 3.82 0.201 0.333 0.389
1100 0.00049 0.00214 4.39 0.203 0.384 0.434
1200 0.00016 0.00079 5.07 0.207 0.439 0.485
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Large k-factors due to poorly modelled LO numbers.
+Provisional 2011 Limits
LIMITS USING LAST WEEKS NUMBERS
WE NOW AGREE ON 5 OBSERVED EVENTS
Using: Observed events = 4 BG= 4.79 +/- 1.38(stat) +/-
0.68(sys)
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2010
+Signal Interpretation
GGM-2D Preliminary results presented
GGM-3D Points exist, but may not make it into immediate paper/note if time
short.
UED: MC ready, preliminary 2011 exclusion limits ~1 week.
SPS8 Not competitive with Tevatron in 2010, should be competitive in 2011. Herwig++ default of 500 GeV used for Graviton in error Currently no useable MC samples Bugfix SLHA files now available Discussing with SUSY MC experts about priorites and timescale for new
SPS8 full simulation samples.
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+Conclusions
We are mainly repeating 2010 analysis with some refinements
Had a first look at the 2011 data . Candidate events are present in the signal . Data appears to agree well with our background model.
We are aiming for a conference note for lepton-photon and to develop our signal interpretation for a paper for the end of the year.
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+Backup
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+Cut Optimization – Jet cut for LAr FEb cleaning
(use photon eta > 1.81)
Remove event if jet with pT> X GeV is pointing to Missing LAr Febs.
What should we use for 2011?
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Jet cutPt (GeV)
QCD EWK Total UED: 1/R = 1300
GGM:900/200
GGM:900/800
Raw S2/B Raw S2/B Raw S2/B
20 1.80 1.89 3.69 2.42 1.59 2.79 2.11 4.75 6.11
40 1.79 1.79 3.69 2.51 1.71 3.02 2.47 5.00 6.78
inf 1.91 2.01 3.92 2.83 2.04 3.97 4.02 5.22 6.95
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