Status of GMSB photons analysis

Shilei Zang(slzang@pizero.colorado.edu)

Bernadette Heyburn, Uriel NauenbergUniversity of Colorado, Boulder

SUSYBSM WG3/WG4 meeting, 24 Aug. 2007

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Outline

• Photonic GMSB sample• Generator studies for signal events, and

comparison with ORCA results• Reconstructed objects• Signal efficiency and background study• Summary and next to do

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Photonic GMSB Sample• Bob Hirosky’s GMSB sample (prompt photon).

Gen-Sim: CMSSW_1_4_6;

Dig-Rec: CMSSW_1_5_3.

About 8250 events (I used 7999 evts for this report) .• Lmd=100TeV; M_mess=2Lmd; N=1; tanBeta=15; sig(mu)=+1; M_top=

175GeV; C_grav=1. (ctau=0.115mm, or ctau=0?)• MSEL=0 and MSUB(244)=1, only gg~g~g generated. (xSection~0.4

92pb)

Francesco’s GMSB sample (prompt photon).

CMKINOSCARORCA Same GMSB parameters as above Bob’s. MSEL=39, all SUSY processes included.

xSection(total SUSY)~0.439pb; xSection(gg~g~g)~0.05pb. All the plots on Francesco’s sample are provided by Francesco.

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GMSB photons

• high pT photons• large MET due to gr

avitinos• multi-jets

Experimental signature

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Generator studies for signal events

• Number of generator photons

• PT and Eta of generator photons

• MET from gravitinos and from gen• Quarks from SUSY particle• Neutralino’s vertex and flight distance

Start from generator level in order to check the GMSB sample, compare with ORCA results, and define the selection criteria for the future analysis.

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Number of generator photons

• Photons from neutralino decay:• BR of neutralino from Isajet:

2 photons~90.14%

1 photon~9.58%0 photon

~0.29%

• BR(LSP+photon)~95%

• BR(LSP+Z0)~3%

• BR(LSP+ e+e-)~2%

• BR(LSP+H0)~10-4%

• 95%*95%=90.25%

• 2*5%*95%=9.5%

• 5%*5%=0.25%

Number of photons from NLSP decay per event

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PT of generator photons

PT(peak)~100GeV PT(peak)~40GeV

1st photon CMSSW

2nd photon CMSSW

71.7% PT>90GeV 79.5% PT>30GeV

1st photon ORCA

2nd photon ORCA

PT PT

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Eta of generator photons

~89% in barrel

~78% in barrel

Barrel: |eta|<1.479

1st photon CMSSW

2nd photon CMSSW

1st photon ORCA

2nd photon ORCA

Eta

Eta Eta

Eta

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MET from gravitinos and from gen

MET from neutrinos and gravitinos.

peak~100GeV peak~140GeV

CMSSW CMSSW

ORCA ORCA

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MET from gravitinos vs from gen

CMSSW

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Quarks from SUSY particle• Mother of selected quarks is a SUSY particle.• Sample includes only gg~g~g process,

and BR(~gSUSY+qqbar)~98.6%, and 98.6%*98.6%=97.2%. quarks(4,6,8,10)~97%

Number of quarks from SUSY decay Type of quarks (pid)

du

sc

b

4 quarks~91.7%

2 quarks~3.1%

0 quark~0.025%

6 quarks~4.5%

8 quarks~0.64%

qbar

10 quarks~0.038%

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Number of quarks per event

• CMSSW result: Sample includes only gg~g~g process• ORCA result: Sample includes all SUSY processes

CMSSW ORCA

Number of quarks from SUSY particle

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PT and Eta of quarks

PT(peak)~160GeV

CMSSW

CMSSW

Eta

PT

87.9% PT>100GeV

ORCA ORCA

PT

PT

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Neutralino’s Vertex

Vetex smeared with Gauss (sigX=sigY=0.0015cm, sigZ=5.3cm)

Gravitino’s vetex minus Neutralino’s vetex equals exactly zero. So ctau=0 exactly? (ctau should equal 0.1144mm?)

Vx Vy

Vz

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Reconstructed objects

• Use SusyAnalyzer under CMSSW_1_5_3• The reconstructed objects are filtered, cleaned, a

nd driven by SusyAnalyzer. • SusyAnalyzer’s default parameters (cuts) are use

d: photonEtaMax=2.5; photonPtMin=20GeV; jetPtMin=30GeV.

• Multiplicity of jets and photons

• PT and eta of jets and photons

• MET from Calorimeter and Recoil

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Multiplicity of jets/photons and Pt of jets

Number of jets

Number of photons

62.9% >=2 phorons

PT of the1st jet

PT of the 2nd jet

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PT and Eta of photons

PT(peak)~100GeV PT(peak)~45GeV

1st photon

1st photon

2nd photon

2nd photon

PT PT

Eta Eta

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MET from Calorimeter, Recoil, and Gen

MetCalo MetRecoil

MetRecoil/MetCalo MetRecoil/MetGen

peak~110GeV peak~120GeV

mean~1.02 mean~0.81

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Signal efficiency

• Francesco’s 2 gamma selection:

• PT(1st gamma)>90GeV

• PT(2nd gamma)>30GeV

• Abs(eta)<1.479 for both of the gamma (barrel).

• 3022 events selected with Francesco’s 2 gamma selection.• Further require MetRecoil>130GeV 1796 events.• Signal efficiency= 1796/7210 =24.9%

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MET distribution after Francesco’s 2 gamma selection

Final MET of signal sample

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Background study

• QCD:

1) qcd jets (0<pT_hat<4000GeV)

2) gamma jet (pT_hat>40GeV)

• EW background

1) W+jets and Z+jets (0<pT_hat<2200GeV)

2) ttbar inclusive

• Others

1) W+gamma

2) Z+gamma

3) WW, ZZ, WZ

Francesco listed the following bkg need to analyze:

First test with 100000 PhotonJets_Pt_300_500. xSection(bkg)=8.2pb.

xSection(GMSB)=0.492pb. Scale factor: 7999/(100000*0.492/8.2)=1.33

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MET of GMSB and Bkg

MET of PhotonJets_Pt_300_500 (scaled)

MET of GMSB

• Further require MetRecoil>130GeV • Signal efficiency=24.9%;• Bkg(PhotonJets) efficiency = 0.189%

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Summary and next to do

• Generator signal events studied to test the sample and compare with ORCA results. CMSSW results are similar as ORCA’s.

• Reconstructed objects simply analyzed to understand them and SusyAnalyzer

• Tried a background analysis• With Francesco’s cuts, give the efficiency of the signal and of the back

ground sample.

Summary

Next to do

• Further analyze the reconstructed objects after matching with generator particles.

• Find a set of analysis variables to select 2 gamma, and determine the cuts

• Generate some GMSB second vertex (not prompt) photons samples.

• Establish our analysis strategy for GMSB second vertex photons analysis.

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Thank you!