Status of GMSB photons analysis
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Transcript of Status of GMSB photons analysis
Status of GMSB photons analysis
Shilei Zang([email protected])
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!