++

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

2+

15/07/2011SUSY

Search for diphoton events with large MET

Main Backgrounds QCD with instrumental MET W/ttbar events where electrons fake

photons

2

+2010 : SUBMITTED !!!

3

15/07/2011SUSY

+ 3

+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

4

15/07/2011SUSY

+ 4

+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

5+

15/07/2011SUSY

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.

5

+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

6+

15/07/2011SUSY

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

6

+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)

7+

15/07/2011SUSY

7

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

8+

15/07/2011SUSY

8

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.

9+

15/07/2011SUSY

9

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.

10

15/07/2011SUSY

+ 10

+Systematic errors on signal MC

11+

15/07/2011SUSY

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% -

11

*2010 values still used. Updates expected within a week

201

0

+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.

12

15/07/2011SUSY

+ 12

+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.”

13

+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.)

14+

15/07/2011SUSY

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

14

Th

e S

UM

colu

mn is

the

err

or

use

d in t

he lim

it

calc

ula

tion

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)

15+

15/07/2011SUSY

15

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.

16

15/07/2011SUSY

+ 16

+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.

17

15/07/2011SUSY

+ 17

+Backup

18

15/07/2011SUSY

+ 18

+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?

19+

15/07/2011SUSY

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

19