Inclusive search for supersymmetry using the razor variables in pp collisions at √s = 7 TeV

Paper Abstract (submitted to PRL, [arXiv link])

An inclusive search is presented for new heavy particle pairs produced in √s = 7 TeV proton-proton collisions at the LHC using 4.7 +/- 0.1 fb−1 of integrated luminosity. The selected events are analyzed in the 2D razor space of MR, an event-by-event indicator of the heavy particle mass scale, and R, a dimensionless variable related to the missing transverse energy. The third-generation sector is probed using the event heavy-flavor content. The search is sensitive to generic supersymmetry models with minimal assumptions about the superpartner decay chains. No excess is observed in the number of events beyond that predicted by the standard model. Exclusion limits are derived in the CMSSM framework as well as for simplified models. Within the CMSSM parameter space considered, gluino masses up to 800 GeV and squark masses up to 1.35 TeV are excluded at 95% confidence level depending on the model parameters. The direct production of pairs of stop or sbottom quarks is excluded for masses as high as 400 GeV.

Paper Figures

pdf pdf
Projection of the 2D fit result on MR (left) and R2 (right) for the HAD box. The blue histogram is the total standard model prediction as obtained from a single pseudo-experiment based on the 2D fit. The red and green histograms represent a steep-slope component denoted as V + jets first component, and a component that encapsulates the steep-slope first component in tt + jets and the effective second component, which is indistinguishable for the different SM background processes. The fit is performed in the R2-M fit region and projected into the full analysis region. Only the statistical uncertainty band on the background predictions is drawn in these projections.

pdf pdf
The p-values corresponding to the observed number of events in the HAD box signal regions (SRi). The green region indicates the fit region (FR) in the HAD box. Similar results are obtained for the other boxes.

pdf
Observed (solid blue curve) and median-expected (dashed curve, shown with its 1 standard deviation uncertainty band) 95% CL limits in the (m0 , m1/2) CMSSM plane with tan β = 10, A = 0 GeV, and sgn(μ) = +1. Shown separately are the observed HAD-only (solid crimson) and leptonic-only (solid green) 95%CLlimits.

pdf
Summary of the 95% CL excluded largest parent mass as a function of the LSP mass in each of the simplified models studied. Results from the inclusive razor analysis (upper bars) and the b-jet razor analysis (lower bars) are shown.

SUS-11-024: Search for supersymmetry in final states with b-jets using the razor variables at √s = 7 TeV

Physics Analysis Summary (PAS)

PAS-SUS-11-024

PAS Abstract

A search is performed for squarks and gluinos pairs produced in √s = 7 TeV proton-proton collisions with 4.7 fb−1 of data collected by the CMS experiment in 2011 at the CERN Large Hadron Collider. The search is sensitive to generic supersymmetry models provided superpartner particles are kinematically accessible and the final state is b-quark enriched, with minimal assumptions on properties of the lightest superpartner particle. The kinematic consistency of the selected events is tested against the hypothesis of heavy particle pair production using the dimensionless razor variable R, related to the missing transverse energy ETmiss. The new physics signal is characterized by a broad peak in the distribution of MR, an event-by-event indicator of the heavy particle mass scale. After background modeling based on data no significant deviation is observed from the Standard Model expectation. The results are interpreted in the context of b-enriched new physics simplified models.

Fit Result Projected on MR and R2: Dilepton Boxes




Projection of the 2D fit result on MR (left) and R2 (right) for the MU-MU, MU-ELE and ELE-ELE b-tagged boxes using the razor datasets.The blue histogram is the total Standard Model prediction as obtained from a single pseudo-experiment based on the 2D fit. The fit is performed in the R2-MR sideband and projected into the full region. Only the statistical error on the total SM background prediction is shown.




Fit Result Projected on MR and R2: Lepton and Had Boxes




Projection of the 2D fit result on MR (left) and R2 (right) for the MU (top), ELE (center), HAD (bottom) b-tagged boxes in the 2011 razor triggered dataset. The blue histogram is the total Standard Model prediction as obtained from a single pseudo-experiment based on the 2D fit. The green, red, and yellow histograms show the breakdown of the Standard Model prediction into separate components as returned by the fit; as verified in simulation, these correspond approximately to the contributions from W,Z + jets and tt ̄. The fit is performed in the R2-MR sideband and projected into the full region. Only the statistical error on the total SM background prediction is shown.




Data vs Background prediction: Dilepton Boxes


The p-values corresponding to the observed number of events in the MU-MU (top), MU-ELE (center), and ELE-ELE (bottom) b-tagged boxes signal regions defined for this anal- ysis. The green dotted lines indicate the fit regions. The p-values test the compatibility of the observed number of events in data with the SM expectation (obtained from the background parameterization).




Data vs Background prediction: Lepton and Had Boxes


The p-values corresponding to the observed number of events in the MU (top), ELE (middle), and HAD (bottom) b-tagged boxes signal regions defined for this analysis. The green dotted lines indicate the fit regions. The p-values test the compatibility of the observed number of events in data with the SM expectation (obtained from the background parameterization).



T1bbbb - Di-gluino production resulting in 4 b quarks + MET final states



Interpretation of inclusive b-tag razor analysis in T1bbbb SMS models. Color-scale (z-axis) indicates the observed cross-section upper limit for each model point, as a function of gluino and LSP mass. Solid black line indicates observed exclusion region, assuming nominal NLO+NLL di-gluino production cross section. Dotted black lines show observed exclusion taking +- 1 sigma theory errors around nominal cross section. Solid green line indicates median expected exclusion region, with dotted green lines indicating the expected exclusion with +- 1 sigma experimental uncertainties. The solid grey region indicates model points where the analysis was found to have dependence on ISR modeling in simulation of signal events above a pre-defined tolerance; no interpretation is presented for these model points. pdf ROOT file

pdf pdf pdf
Efficiencies of signal regions for T1bbbb SMS models, for different lepton-ID-based final states, as a function of gluino and LSP mass. ROOT file

T2bb - Di-sbottom production resulting in 2 b quarks + MET final states



Interpretation of inclusive b-tag razor analysis in T2bb SMS models. Color-scale (z-axis) indicates the observed cross-section upper limit for each model point, as a function of sbottom and LSP mass. Solid black line indicates observed exclusion region, assuming nominal NLO+NLL di-sbottom production cross section. Dotted black lines show observed exclusion taking +- 1 sigma theory errors around nominal cross section. Solid green line indicates median expected exclusion region, with dotted green lines indicating the expected exclusion with +- 1 sigma experimental uncertainties. The solid grey region indicates model points where the analysis was found to have dependence on ISR modeling in simulation of signal events above a pre-defined tolerance; no interpretation is presented for these model points. pdf ROOT file

pdf pdf pdf
Efficiencies of signal regions for T2bb SMS models, for different lepton-ID-based final states, as a function of sbottom and LSP mass. ROOT file

T1tttt - Di-gluino production resulting in 4 top quarks + MET final states



Interpretation of inclusive b-tag razor analysis in T1tttt SMS models. Color-scale (z-axis) indicates the observed cross-section upper limit for each model point, as a function of gluino and LSP mass. Solid black line indicates observed exclusion region, assuming nominal NLO+NLL di-gluino production cross section. Dotted black lines show observed exclusion taking +- 1 sigma theory errors around nominal cross section. Solid green line indicates median expected exclusion region, with dotted green lines indicating the expected exclusion with +- 1 sigma experimental uncertainties. pdf ROOT file

pdf pdf pdf
pdf pdf pdf
Efficiencies of signal regions for T1tttt SMS models, for different lepton-ID-based final states, as a function of gluino and LSP mass. ROOT file

T2tt - Di-stop production resulting in 2 top quarks + MET final states



Interpretation of inclusive b-tag razor analysis in T2tt SMS models. Color-scale (z-axis) indicates the observed cross-section upper limit for each model point, as a function of stop and LSP mass. Solid black line indicates observed exclusion region, assuming nominal NLO+NLL di-stop production cross section. Dotted black lines show observed exclusion taking +- 1 sigma theory errors around nominal cross section. Solid green line indicates median expected exclusion region, with dotted green lines indicating the expected exclusion with +- 1 sigma experimental uncertainties. The solid grey region indicates model points where the analysis was found to have dependence on ISR modeling in simulation of signal events above a pre-defined tolerance; no interpretation is presented for these model points. pdf ROOT file

pdf pdf pdf
pdf pdf pdf
Efficiencies of signal regions for T2tt SMS models, for different lepton-ID-based final states, as a function of stop and LSP mass. ROOT file

Using the razor analysis in phenomenology studies

We provide a how-to to guide to implement the razor analysis in phenomenology studies outside CMS.

-- ChristopherRogan - 27-Jun-2012

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf CMSSM_razor-inclusive.pdf r1 manage 61.5 K 2013-02-06 - 01:28 ChristopherRogan  
PNGpng CMSSM_razor-inclusive.png r1 manage 260.5 K 2013-02-06 - 01:27 ChristopherRogan  
PDFpdf HADBOX-MR.pdf r1 manage 138.8 K 2013-02-06 - 01:28 ChristopherRogan  
PNGpng HADBOX-MR.png r1 manage 75.8 K 2013-02-06 - 01:27 ChristopherRogan  
PDFpdf HADBOX-RSQ.pdf r1 manage 140.8 K 2013-02-06 - 01:27 ChristopherRogan  
PNGpng HADBOX-RSQ.png r1 manage 67.3 K 2013-02-06 - 01:27 ChristopherRogan  
PDFpdf RazB_EleEle_MR_FULL.pdf r1 manage 15.1 K 2012-07-02 - 11:11 MaurizioPierini  
PNGpng RazB_EleEle_MR_FULL.png r1 manage 73.2 K 2012-07-02 - 11:11 MaurizioPierini  
PDFpdf RazB_EleEle_Rsq_FULL.pdf r1 manage 16.0 K 2012-07-02 - 11:11 MaurizioPierini  
PNGpng RazB_EleEle_Rsq_FULL.png r1 manage 78.0 K 2012-07-02 - 11:11 MaurizioPierini  
PDFpdf RazB_Ele_MR_FULL.pdf r1 manage 18.5 K 2012-07-02 - 11:11 MaurizioPierini  
PNGpng RazB_Ele_MR_FULL.png r1 manage 103.2 K 2012-07-02 - 11:11 MaurizioPierini  
PDFpdf RazB_Ele_Rsq_FULL.pdf r1 manage 17.8 K 2012-07-02 - 11:11 MaurizioPierini  
PNGpng RazB_Ele_Rsq_FULL.png r1 manage 88.6 K 2012-07-02 - 11:11 MaurizioPierini  
PDFpdf RazB_Had_MR_FULL.pdf r1 manage 18.3 K 2012-07-02 - 11:11 MaurizioPierini  
PNGpng RazB_Had_MR_FULL.png r1 manage 103.4 K 2012-07-02 - 11:11 MaurizioPierini  
PDFpdf RazB_Had_Rsq_FULL.pdf r1 manage 18.0 K 2012-07-02 - 11:12 MaurizioPierini  
PNGpng RazB_Had_Rsq_FULL.png r1 manage 92.7 K 2012-07-02 - 11:12 MaurizioPierini  
PDFpdf RazB_MuEle_MR_FULL.pdf r1 manage 15.3 K 2012-07-02 - 11:18 MaurizioPierini  
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PDFpdf RazB_MuMu_MR_FULL.pdf r1 manage 16.0 K 2012-07-02 - 11:13 MaurizioPierini  
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PDFpdf RazB_Mu_MR_FULL.pdf r1 manage 17.8 K 2012-07-02 - 11:12 MaurizioPierini  
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PDFpdf RazB_Mu_Rsq_FULL.pdf r2 r1 manage 18.0 K 2012-07-02 - 17:08 MaurizioPierini  
PNGpng RazB_Mu_Rsq_FULL.png r2 r1 manage 90.5 K 2012-07-02 - 17:08 MaurizioPierini  
Unknown file formatroot Razor_btag_SMS_T1bbbb_eff.root r1 manage 18.8 K 2012-06-25 - 14:04 ChristopherRogan  
Unknown file formatroot Razor_btag_SMS_T1bbbb_sigma_UL.root r1 manage 35.3 K 2012-06-27 - 01:40 ChristopherRogan  
Unknown file formatroot Razor_btag_SMS_T1tttt_eff.root r1 manage 28.1 K 2012-06-25 - 14:04 ChristopherRogan  
Unknown file formatroot Razor_btag_SMS_T1tttt_sigma_UL.root r1 manage 21.9 K 2012-06-27 - 01:40 ChristopherRogan  
Unknown file formatroot Razor_btag_SMS_T2bb_eff.root r1 manage 17.8 K 2012-06-25 - 14:04 ChristopherRogan  
Unknown file formatroot Razor_btag_SMS_T2bb_sigma_UL.root r1 manage 35.7 K 2012-06-27 - 01:40 ChristopherRogan  
Unknown file formatroot Razor_btag_SMS_T2tt_eff.root r1 manage 40.0 K 2012-06-25 - 14:04 ChristopherRogan  
Unknown file formatroot Razor_btag_SMS_T2tt_sigma_UL.root r1 manage 31.3 K 2012-06-27 - 01:40 ChristopherRogan  
PDFpdf SMS_summary_razor.pdf r1 manage 166.4 K 2013-02-06 - 01:27 ChristopherRogan  
PNGpng SMS_summary_razor.png r1 manage 48.7 K 2013-02-06 - 01:27 ChristopherRogan  
JPEGjpg SR_EFF_ELE-ELE_T1tttt_btag.jpg r1 manage 212.9 K 2012-06-24 - 17:33 ChristopherRogan  
PDFpdf SR_EFF_ELE-ELE_T1tttt_btag.pdf r1 manage 24.4 K 2012-06-24 - 17:33 ChristopherRogan  
JPEGjpg SR_EFF_ELE-ELE_T2tt_btag.jpg r1 manage 201.8 K 2012-06-24 - 17:38 ChristopherRogan  
PDFpdf SR_EFF_ELE-ELE_T2tt_btag.pdf r1 manage 26.4 K 2012-06-24 - 17:38 ChristopherRogan  
JPEGjpg SR_EFF_ELE-MU_T1tttt_btag.jpg r1 manage 204.8 K 2012-06-24 - 17:36 ChristopherRogan  
PDFpdf SR_EFF_ELE-MU_T1tttt_btag.pdf r1 manage 24.3 K 2012-06-24 - 17:36 ChristopherRogan  
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PDFpdf SR_EFF_ELE-MU_T2tt_btag.pdf r1 manage 26.3 K 2012-06-24 - 17:38 ChristopherRogan  
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PDFpdf SR_EFF_ELE_T2tt_btag.pdf r1 manage 26.6 K 2012-06-24 - 17:38 ChristopherRogan  
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PDFpdf SR_EFF_HAD_T1bbbb.pdf r1 manage 43.0 K 2012-06-24 - 17:34 ChristopherRogan  
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