susy searches with one photon at cms
DESCRIPTION
FSP-CMS Meeting 1-2 October 2012 DESY Zeuthen. SUSY Searches with One Photon at CMS. Valentina Sola ( Universität Hamburg ). GMSB and GGM Photon S earches at CMS Results and Limits. GMSB and GGM. Gauge-Mediated SUSY Breaking (GMSB) - PowerPoint PPT PresentationTRANSCRIPT
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SUSY Searches with One Photon at CMS
Valentina Sola(Universität Hamburg)
GMSB and GGM Photon Searches at CMS Results and Limits
FSP-CMS Meeting1-2 October 2012DESY Zeuthen
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LHC Physics Discussion - 10/9/2012 2
GMSB and GGM Gauge-Mediated SUSY Breaking (GMSB) [ G. Giudice and R. Rattazzi, arXiv:hep-ph/9801271 ] = SUSY couples to normal matter through gauge interactions = Gravitino: LSP
General Gauge Mediation (GGM) [ P. Meade, N. Seiberg, D. Shih, arXiv:0801.3278 ] = neutralino NLSP a mixture of Bino, Wino and Higgsino = photon/Z+Gravitino or W+Gravitino final states -> one (or two) photon(s) + MET = focus on strong production: many jets
V. Sola
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LHC Physics Discussion - 10/9/2012 3
GGM Phenomenology @ the LHC
V. Sola
Neutralino NLSP mixture of Bino, Wino and Higgsino Bino-like NLSP:
Wino-like (co-)NLSP:
Bino-Higgsino-like NLSP:
R-parity is conserved -> 2 LSPs per event ★ MET is defining signature
[ J. Ruderman, D. Shih, arXiv:1103.6083 ]
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LHC Physics Discussion - 10/9/2012 4
GGM with One Photon at CMS
V. Sola
Final states with at least one photon γ + Jets + METIt includes the case ofBino-Higgsino-like NSLPγ + h + MET
Results presented in ICHEP 2012 ∫ L dt = 4.04 fb-1 2012 Data @ √s = 8 TeV [ CMS Collaboration, PAS-12-018; AN-2012-154 ]
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LHC Physics Discussion - 10/9/2012 5
Trigger Efficiency
V. Sola
Analysis trigger: HLT_Photon70_CaloIdXL_PFHT400Baseline triggers: HLT_Photon50_CaloIdVL (prescale = 900) HLT_Photon75_CaloIdVL (prescale = 150) HLT_PFHT350 (prescale = 1000)
Trigger is fully efficient within an uncertainty of 4%
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LHC Physics Discussion - 10/9/2012 6
Event Selection
V. Sola
Jets = particle flow jets, anti-kT (R=0.5), photon rejectedHT = scalar sum of pT of all jets with pT>40 GeV and |η|<3, no photon rejection
Photons ≥ 1ET > 80 GeVEiso
(∆R<0.3) < 6 GeV|η| < 1.442Jets ≥ 2pT > 30 GeV|η| < 2.6HT > 450 GeVMET > 100 GeV
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LHC Physics Discussion - 10/9/2012 7
Standard Model Backgrounds
V. Sola
Fake photons -QCD (jets)
Fake photons –EWK (electrons)
Irreducible(photons)
γ + Jetj → γ
Dominant Background
Data - Driven
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LHC Physics Discussion - 10/9/2012 8
QCD Background
V. Sola
Mis-measurement of MET in QCD processes-> direct di-photon, photon+jets, and multijet production with jets mimicking photons ✓ looser γ isolation requirements (γjet) orthogonal to signal selection ✓ pT spectra reweighted in low MET region (MET<100 GeV) ✓ systematic uncertainty of 10% assigned
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LHC Physics Discussion - 10/9/2012 9
Standard Model Backgrounds
V. Sola
Fake photons -QCD (jets)
Fake photons –EWK (electrons)
Irreducible(photons)
γ + Jetj → γ
W, tope →γ
Dominant Background
Sub-dominantBackground
Data - Driven Data - Driven
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LHC Physics Discussion - 10/9/2012 10
EWK Background
V. Sola
Events with true MET and an electron misidentified as a photon-> compare Z→ee events to Z→eγ to obtain e→γ fake rate
Ratio of signal used to estimate fake rate fe→γ
pT > 80 GeV: fe→γ = 0.011 ± 0.002 (stat) ± 0.001 (syst)Inclusive electron spectrum scaled by fe→γ to obtain EWK bkg
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LHC Physics Discussion - 10/9/2012 11
Standard Model Backgrounds
V. Sola
Fake photons -QCD (jets)
Fake photons –EWK (electrons)
Irreducible(photons)
γ + Jetj → γ
W, tope →γ
ISR/FSRZ/W/top + γ
Dominant Background
Sub-dominantBackground
Sub-dominantBackground
Data - Driven Data - Driven Simulation
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LHC Physics Discussion - 10/9/2012 12
Standard Model Backgrounds
V. Sola
MadGraph50% uncertainty
on the Xsec
Fake photons -QCD (jets)
Fake photons –EWK (electrons)
Irreducible(photons)
γ + Jetj → γ
W, tope →γ
ISR/FSRZ/W/top + γ
Dominant Background
Sub-dominantBackground
Sub-dominantBackground
Data - Driven Data - Driven Simulation
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LHC Physics Discussion - 10/9/2012 13
Single Photon MET Spectrum
No excess observed over SM expectations
Six bins in MET > 100 GeV used to set limits [100, 120, 160, 200, 270, 350, ∞)
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LHC Physics Discussion - 10/9/2012 14
Single Photon Event Display
V. Sola
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LHC Physics Discussion - 10/9/2012 15
Limit Calculation
V. Sola
Systematic errors
= Uncertainty on trigger efficiency 4% = Theory errors: scale and PDF errors combined at each point and cross section varied by 1σ Limit calculation = CLS method with likelihood-ratio test statistics at 95% = full propagation of errors = GGM Signal Monte Carlo (grid scan) Prospino used for NLO cross section
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LHC Physics Discussion - 10/9/2012 16
Interpretation: Bino-like NLSP
V. Sola
Bino-like GGM scanmχ0 = 375 GeV, msquark,gluino = 400-2000 GeV (step 80 GeV)sleptons and all gauginos except NLSP @ 3.5 TeV
γ + ≥2 jets + MET γ + ≥2 jets + MET
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LHC Physics Discussion - 10/9/2012 17
Interpretation: Wino-like NLSP
V. Sola
Wino-like GGM scanmχ0 = 375 GeV, msquark,gluino = 400-2000 GeV (step 80 GeV)sleptons and all gauginos except NLSP @ 3.5 TeV
γ + ≥2 jets + MET γ + ≥2 jets + MET
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LHC Physics Discussion - 10/9/2012 18
Updated MET Spectrum
V. Sola
Json: 27Aug ∫L dt = 9.4 fb-1
CMSSW: 532patch1
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LHC Physics Discussion - 10/9/2012 19
Summary and Outlook
V. Sola
CMS analysis designed to cover a broad range of final state SUSY GMSB scenarios = Preliminary results with 4 fb-1 of 8 TeV data collected in 2012 = data-driven background estimate for QCD/EWK sources = no excesses seen over SM predictions
Exclusion limits set in bino- and wino-like neutralino NLSP = Bino like: msquark < 1.2 TeV, mgluino < 1.1 TeV excluded = Wino like: msquark < 900 GeV, mgluino < 800 GeV excluded
Results with full 2012 statistics foreseen in Moriond2013 = increased statistics = optimised analysis = b-tagging and angle variable investigation will be included