Transcript + + 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 Inclusive.

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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
Inclusive search for SUSY
with photons and EtMiss
final states
Helen Hayward on behalf of the SUSY-Pho
group
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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

Search for diphoton events with large
MET

Main Backgrounds
QCD with instrumental MET
W/ttbar events where electrons fake
photons


SUSY
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SUSY
2010 : SUBMITTED !!!
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Selection
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Require two selected photons in the event.

Currently implemented cuts:
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SUSY
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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
15/07/2011
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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)
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
SUSY
GRL:
 data11_7TeV.periodAllYear_DetStatusv18-pro08-04_CoolRunQuery-00-0398_Susy_ph_met.xml
 (will update to -05)
 Requires good photon and electron
triggers
 Requires good photons, leptons,
jets,MET

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

γη
Optimise using best s2/b =>η<1.81
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
SUSY
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Data Driven BG estimate I
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SUSY
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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

Understanding the QCD control
sample normalization issues
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Understanding the QCD control
sample shape issue (twophoton versus one-photon control
sample)
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SUSY
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Data Driven BG estimate II
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To estimate BG from genuine MET
sources Electron-Photon control
sample
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Scale by electron->photon fake
rate
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Subtract QCD/Z->ee
contamination by using QCD
template
 (the blue histogram in figure)
 Difference is estimate of W and
Ttbar contributions
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MC templates are scaled to data
for 40<MET<125 GeV
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Need to add Wgamma MC samples
to this plot
 ~ few days
2010:Cone20/Et<0.1
2011:EtCone20_cor<5GeV
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BG results

DiJet,PhoJet,PhoPho BG : Predicted
background above 125 GeV = 2.73
 +/- 0.86 (stat)
 +/-0.59(template shape)
 +/- 0.088(template scale)
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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)
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QCD+EWK = 5.6 +/- 1.3(stat) +/- 0.7(sys)
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Zgg=0.12+/-0.014(stat)
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Wgg=0.019+/-0.009(stat)
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Total = 5.8+/-1.3(stat)+/-0.7(sys)
SUSY
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QCD template is normalised to
the diphoton distribution for
MET< 20 GeV
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W/ttbar entries in 1st bin are
artifact of this scaling.
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Non collision BG
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 Cosmics:
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Use L1_EM3_EMPTY triggers to determine the rate of tight
diphotons per unit time per bunch in cosmic events.
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Assumed to pass the primary vertex cut by being overlaid with
a minbias event.
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Background demonstrated to negligible in 2010
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Estimate for 2011 due < 1 week
 Beam
SUSY
background
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Use unpaired bunches
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<2 weeks.
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Systematic errors on signal MC
Source of
Uncertainty
Uncertainty
GGM
UED
Lumi
3.7%
Trigger
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10%
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Photon
Identification
Photon
Isolation
Pileup
2010
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MET
3.7%*
1.1%*
Signal MC
stats
7.6%*
5.4%*
10-48%
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PDF and scale
SUSY
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*2010 values still used. Updates
expected within a week
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List of Egamma Systematics I
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Trigger
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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
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SUSY
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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
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Identification
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Material
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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
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
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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.”
Mgluino
LO (pb)
NLO (pb)
K-factor
Scale
PDF
SUM
√(scale2+p
df2)
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
SUSY
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values in Scale/PDF/SUM are relative value against
the NLO sigma.
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e.g. at Mgl=1000GeV, the error is 38.9%.
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Scale is estimated by changing the
Factorization/Normalization scales by x1/2 and x2,
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PDF errors (90% CL) are translated to 68% by
dividing them by 1.645.
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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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The SUM column is the error
used in the limit calculation
+ Preliminary PDF and scale errors
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Large k-factors due to poorly
modelled LO numbers.
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Provisional 2011 Limits
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LIMITS USING LAST WEEKS
NUMBERS
WE NOW AGREE ON 5 OBSERVED
EVENTS
Using:
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Observed events = 4
BG= 4.79 +/- 1.38(stat) +/- 0.68(sys)
2010
SUSY
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Signal Interpretation
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GGM-2D
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MC ready, preliminary 2011 exclusion limits ~1 week.
SPS8
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SUSY
Points exist, but may not make it into immediate paper/note if time short.
UED:
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Preliminary results presented
GGM-3D
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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.
15/07/2011
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Conclusions
 We
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are mainly repeating 2010 analysis with some refinements
 Had
a first look at the 2011 data .

Candidate events are present in the signal .
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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.
SUSY
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SUSY
Backup
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Cut Optimization – Jet cut for LAr
FEb cleaning
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(use photon eta > 1.81)
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Remove event if jet with pT> X GeV is pointing to Missing LAr Febs.
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What should we use for 2011?
Jet
QCD EWK Total UED:
cut
1/R = 1300
Pt
Raw S2/B
(GeV)
GGM:
900/200
GGM:
900/800
Raw
S2/B
Raw
S2/B
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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
SUSY
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15/07/2011