Performance of Methods for Data-Driven Background Estimation in SUSY Searches

Abstract

Searches for supersymmetry (SUSY) involve a broad range of signatures with jets, leptons, photons, and missing transverse energy (MET). These searches require careful control over backgrounds from standard model processes. Several methods for data-driven background determinations were developed and tested on early LHC pp collision data collected by the CMS experiment at √s=7 TeV. These data allow us to study QCD backgrounds, to evaluate methods to control jet-energy mis-measurement, to validate data-driven methods for predicting the background MET distribution, and to measure background contributions from processes producing non-prompt leptons or hadrons misidentified as leptons.

Approved Plots from SUS-10-001 ( click on plot to get .pdf )

Figure Abbreviated Caption
Figure_001-a.gif Plots of the αT distribution made with calorimeter-based jets.
Figure_001-b.gif Plots of the αT distribution made with calorimeter-based jets.
Figure_001-c.gif Plots of the αT distribution made with calorimeter-based jets.
Figure_001-d.gif Plots of the αT distribution made with calorimeter-based jets.
Figure_002-a.gif Fraction of events passing an αT > 0.55 cut as a function of HT. Di-jet and γ + 1 jet samples. The effects of jet loss and jet smearing are also shown.
Figure_002-b.gif Fraction of events passing an αT > 0.55 cut as a function of HT. ≥ 3 jets and γ+ ≥ 2 jets samples. The effects of jet loss and jet smearing are also shown.
Figure_003.gif Fraction of events in data and minimum bias MC passing an αT > 0.55 cut as a function of η of the leading jet.
Figure_004-a.gif The αT distribution for events with selected (points with error bars) and anti-selected electrons (histogram).
Figure_004-b.gif The αT distribution for events with selected (points with error bars) and anti-selected electrons (histogram). Events with MET< 20 GeV, which suppresses W contamination.
Figure_005-a.gif Distributions of ∆φ for a di-jet sample under various con- ditions.
Figure_005-b.gif Distributions of ∆φ for a multi-jet sample under various con- ditions.
Figure_006.gif ∆φ(MPT, MHT) distribution in multi-jet events and in events with real MHT emulated by removal of one jet.
Figure_007.gif ∆φ(MPT, MHT) distribution from multi-jet data with hadronic and electromagnetic calorimeter noise.
Figure_008.gif Templates from data describing MET from jet resolution and mismeasurement effects. The data are shown by points with error bars and the Pythia6 QCD MC by the histograms. Each template corresponds to a sample with a specific number of jets (rows) and a range in HT (columns).
Figure_009.gif MET predictions, based on templates, compared to the observed MET in γ+ ≥ 3 jet events. The data are shown by points with error bars and the predictions are shown by histograms. Particle-flow reconstruction is used.
Figure_010.gif Comparisonofthedi-photonMETdistributionwiththepredictionobtainedfrom a sample with two non-isolated photon candidates.
Figure_011-a.gif Fit to the distribution of relative isolation of electrons for pT > 10 GeV sample.
Figure_011-b.gif Fit to the distribution of relative isolation of electrons for pT > 10 GeV sample, with MET < 20 GeV to suppress W events.
Figure_012-a.gif Predicted vs. measured number of isolated electrons (relative isolation<0.3) from background sources as a function of HT.
Figure_012-b.gif Predicted vs. measured number of isolated electrons (relative isolation<0.3) from background sources as a function of HT for events with low MET, which suppresses W → eν to obtain a background dominated sample.
Figure_013-a.gif Isolation distribution for muons with fitted contributions from prompt and non-prompt muons for all selected events with MET > 20 GeV.
Figure_013-b.gif Isolation distribution for muons with fitted contributions from prompt and non-prompt muons for background dominated events selected with MET < 20 GeV and HT > 20 GeV.
Figure_014.gif Jet multiplicity distribution (left) and the muon pT distribution (right) for data and a muon enriched QCD Monte Carlo sample. The ttbar shape is also shown, with a separate normalization defined by the right-hand scale. The last bins include overflow entries.
Figure_015-a.gif Measured muon isolation distributions using the tag-and-probe method in data (black markers) and in a muon enriched QCD MC (blue shaded curve). The last bins include overflow entries.
Figure_015-b.gif Measured muon isolation distributions using the tag-and-probe method in data (black markers) and in a muon enriched QCD MC (blue shaded curve). The last bins include overflow entries.
Figure_016.gif The measured muon isolation distribution after re-weighting for pT(μ) and jet multiplicity using MC events. The distributions are normalized to unity and overflow entries are added to the last bin.
Figure_017.gif Efficiency as a function of the muon isolation cut in loosely selected same-sign di-muon data.
Figure_018-a.gif Tight-to-Loose (TL) ratios for electrons as a function of pT measured in different jet samples.
Figure_018-b.gif Tight-to-Loose (TL) ratios for muons as a function of pT measured in different jet samples.
Figure_019-a.gif Plots of the αT distribution made with the Jet-plus-tracks algorithm.
Figure_019-b.gif Plots of the αT distribution made with the Jet-plus-tracks algorithm.
Figure_019-c.gif Plots of the αT distribution made with the Jet-plus-tracks algorithm.
Figure_019-d.gif Plots of the αT distribution made with the Jet-plus-tracks algorithm.
Figure_020-a.gif Plots of the αT distribution made with the Particle Flow algorithm.
Figure_020-b.gif Plots of the αT distribution made with the Particle Flow algorithm.
Figure_020-c.gif Plots of the αT distribution made with the Particle Flow algorithm.
Figure_020-d.gif Plots of the αT distribution made with the Particle Flow algorithm.

Link to SUS-10-001 PAS in CDS

Topic attachments
I Attachment History Action Size Date Who Comment
GIFgif Figure_001-a.gif r1 manage 54.3 K 2010-08-06 - 17:30 AlexTapper  
GIFgif Figure_001-b.gif r1 manage 49.7 K 2010-08-06 - 17:31 AlexTapper  
GIFgif Figure_001-c.gif r1 manage 42.7 K 2010-08-06 - 17:31 AlexTapper  
GIFgif Figure_001-d.gif r1 manage 43.9 K 2010-08-06 - 17:31 AlexTapper  
GIFgif Figure_002-a.gif r1 manage 47.6 K 2010-08-06 - 17:31 AlexTapper  
GIFgif Figure_002-b.gif r1 manage 56.2 K 2010-08-06 - 17:32 AlexTapper  
GIFgif Figure_003.gif r1 manage 29.9 K 2010-08-06 - 17:34 AlexTapper  
GIFgif Figure_004-a.gif r1 manage 57.8 K 2010-08-06 - 17:34 AlexTapper  
GIFgif Figure_004-b.gif r1 manage 60.2 K 2010-08-06 - 17:34 AlexTapper  
GIFgif Figure_005-a.gif r1 manage 63.4 K 2010-08-06 - 17:35 AlexTapper  
GIFgif Figure_005-b.gif r1 manage 59.6 K 2010-08-06 - 17:35 AlexTapper  
GIFgif Figure_006.gif r1 manage 95.9 K 2010-08-06 - 17:35 AlexTapper  
GIFgif Figure_007.gif r1 manage 54.3 K 2010-08-06 - 17:35 AlexTapper  
GIFgif Figure_008.gif r1 manage 72.6 K 2010-08-06 - 17:36 AlexTapper  
GIFgif Figure_009.gif r1 manage 33.1 K 2010-08-06 - 17:37 AlexTapper  
GIFgif Figure_010.gif r1 manage 37.0 K 2010-08-06 - 17:37 AlexTapper  
GIFgif Figure_011-a.gif r1 manage 142.8 K 2010-08-06 - 17:37 AlexTapper  
GIFgif Figure_011-b.gif r1 manage 145.6 K 2010-08-06 - 17:38 AlexTapper  
GIFgif Figure_012-a.gif r1 manage 71.0 K 2010-08-06 - 17:38 AlexTapper  
GIFgif Figure_012-b.gif r1 manage 74.1 K 2010-08-06 - 17:38 AlexTapper  
GIFgif Figure_013-a.gif r1 manage 65.7 K 2010-08-06 - 17:40 AlexTapper  
GIFgif Figure_013-b.gif r1 manage 77.3 K 2010-08-06 - 17:40 AlexTapper  
GIFgif Figure_014.gif r1 manage 40.9 K 2010-08-06 - 17:40 AlexTapper  
GIFgif Figure_015-a.gif r1 manage 34.9 K 2010-08-06 - 17:40 AlexTapper  
GIFgif Figure_015-b.gif r1 manage 35.4 K 2010-08-06 - 17:41 AlexTapper  
GIFgif Figure_016.gif r1 manage 40.9 K 2010-08-06 - 17:41 AlexTapper  
GIFgif Figure_017.gif r1 manage 62.4 K 2010-08-06 - 17:41 AlexTapper  
GIFgif Figure_018-a.gif r1 manage 35.6 K 2010-08-06 - 17:42 AlexTapper  
GIFgif Figure_018-b.gif r1 manage 33.1 K 2010-08-06 - 17:42 AlexTapper  
GIFgif Figure_019-a.gif r1 manage 47.6 K 2010-08-06 - 17:42 AlexTapper  
GIFgif Figure_019-b.gif r1 manage 44.4 K 2010-08-06 - 17:43 AlexTapper  
GIFgif Figure_019-c.gif r1 manage 41.6 K 2010-08-06 - 17:43 AlexTapper  
GIFgif Figure_019-d.gif r1 manage 42.7 K 2010-08-06 - 17:43 AlexTapper  
GIFgif Figure_020-a.gif r1 manage 49.0 K 2010-08-06 - 17:44 AlexTapper  
GIFgif Figure_020-b.gif r1 manage 45.6 K 2010-08-06 - 17:44 AlexTapper  
GIFgif Figure_020-c.gif r1 manage 42.7 K 2010-08-06 - 17:44 AlexTapper  
GIFgif Figure_020-d.gif r1 manage 42.5 K 2010-08-06 - 17:45 AlexTapper  
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Topic revision: r5 - 2011-05-27 - MarcoAndreaBuchmann
 
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