Search for supersymmetry in all-hadronic events with αT

This analysis is published in Phys.Rev.Lett. 107 (2011) 221804 and is also available at arXiv:1109.2352.

Abstract

An update of the search for supersymmetry in events with jets and missing transverse energy, based on the analysis in Ref. [1], is presented. The results are based on a data sample of 1.1 fb -1 of integrated luminosity recorded at √s = 7 TeV. In this search, the variable αT is used as the main discriminator between events with real and fake missing transverse energy, and no excess of events over the Standard Model expectation is found. Given this agreement, exclusion limits in the parameter space of the constrained minimal supersymmetric model are set. Squark and gluino masses of 1.1 TeV are excluded for values of the common scalar mass at the GUT scale m0 < 0.5 TeV.

Approved Plots from SUS-11-003 ( click on plot to get .pdf )

Figure Abbreviated Caption
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/HT_all.png HT distribution for HT ≥ 375 GeV and MHT > 100 GeV.
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/JetMultiplicity_all.png Jet Multiplicity distribution for HT ≥ 375 GeV and MHT > 100 GeV.
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/AlphaT.png αT distribution for HT ≥ 375 GeV and full event selection (apart from αT > 0.55).
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/BiasedDeltaPhi_after_alphaT_55_all.png ΔΦ* distribution after αT selection
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/EffectiveMass_after_alphaT_55_all.png Effective Mass Meff = HT + MHT distribution after αT selection
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/JetMultiplicityAfterAlphaT_all.png Jet Multiplicity distribution after αT selection
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/Ratio_Multi2Incl_AlphaT55.png The dependence of RαT on HT
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/Syst_Multi2Incl_AlphaT55.png The dependence of RαT on HT varying the effective cross-section of the four major EWK background components individually by ± 15%.
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/spring11NoLogYaT_HMuonControl_beforeaT.png αT distribution for Muon Control selection before αT cut (HT > 375 GeV applied)
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/spring11NoLogYHTMuonControl_beforeaT.png HT distribution for Muon Control selection before αT cut (HT > 375 GeV applied)
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/spring11NoLogYHTMuonControl_afteraT.png HT distribution for Muon Control selection after αT cut (HT > 375 GeV applied)
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/spring11NoLogYMTMuonControl_afteraT.png MT distribution for Muon Control selection after αT cut (HT > 375 GeV applied)
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/375___xcak5JetAlphaTFewBinsPat.png αT distribution for Photon Control selection before αT cut (HT > 375 GeV applied)
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/375___xcak5JetIndicesPat.png Jet Multiplicity distribution for Photon Control selection before αT cut (HT > 375 GeV applied)

/twiki/pub/CMSPublic/PhysicsResultsSUS11003/HT-Spectrum.png HT distribution showing outcome of fit with respect to hadronic signal events
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/muon_control_fit_logy.png HT distribution showing outcome of fit with respect to muon control events
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/photon_control_fit_logy.png HT distribution showing outcome of fit with respect to photon control events
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/AlphaT-Ratio.png T as a function of HT as observed in data and the result of the fit.

/twiki/pub/CMSPublic/PhysicsResultsSUS11003/RA1_ExclusionLimit_tanb10.png Observed and expected 95% CL exclusion contours in the CMSSM (m0,m1/2) plane (tan β = 10, A0 = 0, μ > 0) using NLO signal cross sections using the CLs method. The expected limit is shown with its 68% CL range.
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/RA1_ExclusionLimit_tanb40.png Observed and expected 95% CL exclusion contours in the CMSSM (m0,m1/2) plane (tan β = 40, A0 = 0, μ > 0) using NLO signal cross sections using the CLs method. The expected limit is shown with its 68% CL range.
/twiki/pub/CMSPublic/PhysicsResultsSUS11003/RA1_ExclusionLimit_tanb10-vs-tanb40.png Comparison of observed and expected 95% CL exclusion contours in the CMSSM (m0,m1/2) plane for tan β = 10 and tan β = 40 (A0 = 0, μ > 0) using NLO signal cross sections and the CLs method.

Re-interpretation in terms of simplified models

The language of simplified models has been introduced recently (see e.g. here and here) to establish an efficient communication channel between the LHC experiments and the theory communities who have proposed a general set of simplified models with which LHC data can be interpreted. A similar approach has been taken before in the hadronic channel with 2010 data -- see here.

The above results have been re-interpreted in terms of the simplified models given in the following table. The signal efficiencies as a function of the mass parameters of the simplified model are also given below, together with upper limit plots on the production cross section. The data for these plots are also available as a ROOT file T1_alphaT.root, T2_alphaT.root T5zz_alphaT.root . The regions with small 
ΔΜ(gluino,LSP)
 and
 low gluino 
mass
 are 
excluded since they are
 dominated by 
statistical 
errors 
and
 signal 
modeling uncertainty. Signal contamination in control regions has not been taken into account when computing the upper limits on the production cross sections.

Simplified model topology name Simplified model topology Efficiency Limit Caption
"T1" T1.png h_eff_T1_alphaT.png h_limit_T1_alphaT.png Upper limit on production cross section, for T1, assuming a branching ratio of 1. Superimposed are 95% CL exclusion contours, assuming a "reference SUSY cross section", for decoupled squarks: m(~q)>>m(~g).
"T2" T2.png h_eff_T2_alphaT.png h_limit_T2_alphaT.png Upper limit on production cross section, for T2, assuming a branching ratio of 1. Superimposed are 95% CL exclusion contours, assuming a "reference SUSY cross section", for decoupled gluino: m(~g)>>m(~q).
"T5zz" T5zz.png h_eff_T5zz_alphaT_efficiency.png h_limit_T2_alphaT_limit.png Upper limit on production cross section, for T5zz, assuming a branching ratio of 1. Superimposed are 95% CL exclusion contours, assuming a "reference SUSY cross section", for decoupled squarks: m(~q)>>m(~g).

Link to SUS-11-003 PRL paper in CDS

Link to SUS-11-003 Physics Analysis Summary (PAS) in CDS

Link to code to calculate αT

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng 375___xcak5JetAlphaTFewBinsPat.png r1 manage 103.6 K 2011-07-27 - 11:02 UnknownUser  
PNGpng 375___xcak5JetIndicesPat.png r1 manage 115.3 K 2011-07-27 - 11:02 UnknownUser  
PDFpdf AlphaT-Ratio.pdf r1 manage 15.2 K 2012-01-10 - 18:47 HenningFlacher AlphaT-Ratio
PNGpng AlphaT-Ratio.png r1 manage 109.5 K 2012-01-10 - 18:47 HenningFlacher AlphaT-Ratio
PDFpdf AlphaT.pdf r1 manage 23.1 K 2012-01-10 - 18:47 HenningFlacher AlphaT
PNGpng AlphaT.png r1 manage 184.9 K 2012-01-10 - 18:48 HenningFlacher AlphaT
PNGpng BiasedDeltaPhi_after_alphaT_55_all.png r1 manage 195.7 K 2011-07-27 - 10:45 UnknownUser  
PNGpng EffectiveMass_after_alphaT_55_all.png r1 manage 138.2 K 2011-07-27 - 10:45 UnknownUser  
PDFpdf HT-Spectrum.pdf r1 manage 14.9 K 2012-01-10 - 18:48 HenningFlacher HT Spectrum
PNGpng HT-Spectrum.png r1 manage 94.8 K 2012-01-10 - 18:48 HenningFlacher HT Spectrum
PNGpng HT_all.png r1 manage 146.5 K 2011-07-27 - 10:48 UnknownUser  
PNGpng JetMultiplicityAfterAlphaT_all.png r1 manage 117.2 K 2011-07-27 - 10:44 UnknownUser  
PNGpng JetMultiplicity_all.png r1 manage 125.5 K 2011-07-27 - 10:47 UnknownUser  
PDFpdf RA1_ExclusionLimit_tanb10-vs-tanb40.pdf r1 manage 20.1 K 2012-01-10 - 18:49 HenningFlacher Limit 10 vs 40
PNGpng RA1_ExclusionLimit_tanb10-vs-tanb40.png r1 manage 177.6 K 2012-01-10 - 18:49 HenningFlacher Limit 10 vs 40
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PNGpng RA1_ExclusionLimit_tanb10.png r1 manage 214.3 K 2012-01-10 - 18:50 HenningFlacher Limit 10
PDFpdf RA1_ExclusionLimit_tanb40.pdf r1 manage 23.0 K 2012-01-10 - 18:50 HenningFlacher Limit 40
PNGpng RA1_ExclusionLimit_tanb40.png r1 manage 204.2 K 2012-01-10 - 18:50 HenningFlacher Limit 40
PNGpng Ratio_Multi2Incl_AlphaT55.png r1 manage 18.0 K 2011-07-26 - 16:42 UnknownUser  
PNGpng Syst_Multi2Incl_AlphaT55.png r1 manage 23.6 K 2011-07-26 - 16:43 UnknownUser  
PDFpdf T1.pdf r1 manage 8.0 K 2011-09-20 - 12:35 MariarosariaDalfonso  
PNGpng T1.png r1 manage 3.4 K 2011-09-20 - 12:35 MariarosariaDalfonso  
Unknown file formatroot T1_alphaT.root r1 manage 10.8 K 2011-09-13 - 13:09 MariarosariaDalfonso  
PDFpdf T2.pdf r1 manage 7.1 K 2011-09-20 - 12:34 MariarosariaDalfonso  
PNGpng T2.png r1 manage 2.5 K 2011-09-20 - 12:34 MariarosariaDalfonso  
Unknown file formatroot T2_alphaT.root r1 manage 10.7 K 2011-09-13 - 13:09 MariarosariaDalfonso  
PDFpdf T5zz.pdf r1 manage 10.2 K 2011-11-18 - 17:27 MariarosariaDalfonso  
PNGpng T5zz.png r1 manage 18.9 K 2011-11-18 - 17:27 MariarosariaDalfonso  
C source code filec alphaT.C r1 manage 1.0 K 2012-02-09 - 14:25 EdwardLaird  
PDFpdf h_eff_T1_alphaT.pdf r1 manage 13.1 K 2011-09-20 - 12:43 MariarosariaDalfonso  
PNGpng h_eff_T1_alphaT.png r1 manage 29.4 K 2011-09-20 - 12:43 MariarosariaDalfonso  
PDFpdf h_eff_T2_alphaT.pdf r1 manage 13.2 K 2011-09-20 - 12:42 MariarosariaDalfonso  
PNGpng h_eff_T2_alphaT.png r1 manage 30.1 K 2011-09-20 - 12:42 MariarosariaDalfonso  
PDFpdf h_eff_T5zz_alphaT_efficiency.pdf r1 manage 7.9 K 2011-11-18 - 17:19 MariarosariaDalfonso T5zz eff
PNGpng h_eff_T5zz_alphaT_efficiency.png r1 manage 106.3 K 2011-11-18 - 17:19 MariarosariaDalfonso T5zz eff png
PDFpdf h_limit_T1_alphaT.pdf r1 manage 14.7 K 2011-09-20 - 12:42 MariarosariaDalfonso  
PNGpng h_limit_T1_alphaT.png r1 manage 41.0 K 2011-09-20 - 12:41 MariarosariaDalfonso  
PDFpdf h_limit_T2_alphaT.pdf r2 r1 manage 8.9 K 2011-11-14 - 15:24 HenningFlacher  
PNGpng h_limit_T2_alphaT.png r3 r2 r1 manage 129.5 K 2011-11-18 - 17:29 MariarosariaDalfonso  
PDFpdf h_limit_T5zz_alphaT_limit.pdf r1 manage 9.1 K 2011-11-18 - 17:21 MariarosariaDalfonso T5zz
PNGpng h_limit_T5zz_alphaT_limit.png r1 manage 130.2 K 2011-11-18 - 17:18 MariarosariaDalfonso T5zz efficiency
PNGpng muon_control_fit_logy.png r1 manage 12.3 K 2011-07-27 - 10:55 UnknownUser  
PNGpng photon_control_fit_logy.png r1 manage 12.1 K 2011-07-27 - 10:55 UnknownUser  
PNGpng spring11NoLogYHTMuonControl_afteraT.png r1 manage 17.7 K 2011-07-27 - 09:45 UnknownUser  
PNGpng spring11NoLogYHTMuonControl_beforeaT.png r1 manage 16.1 K 2011-07-27 - 09:46 UnknownUser  
PNGpng spring11NoLogYMTMuonControl_afteraT.png r1 manage 16.0 K 2011-07-27 - 09:46 UnknownUser  
PNGpng spring11NoLogYaT_HMuonControl_beforeaT.png r1 manage 16.1 K 2011-07-27 - 09:45 UnknownUser  
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