Search for Physics Beyond the Standard Model in Opposite-Sign Dilepton Events in pp Collisions at sqrt(s) = 7 TeV

Abstract

We present results of a search for physics beyond the Standard Model (SM) in final states with opposite-sign isolated lepton pairs accompanied by hadronic jets and missing transverse energy. We use a data sample of 7 TeV proton-proton collisions corresponding to an integrated luminosity of 34 pb-1 collected with the CMS detector at the Large Hadron Collider in 2010. The search is based on a data sample selected with high pT lepton triggers and an independent sample based on large hadronic activity triggers. Backgrounds are estimated from different data control samples and compared with SM Monte Carlo simulation. We find no evidence for anomalous event yield beyond SM expectations and place an upper limit on the non-SM contribution to our chosen signal region. We interpret the limit in the context of the CMSSM parameter space and find that the region excluded by our results exceeds those previously set by the Tevatron and LEP experiments. We also provide information to test whether specific models of physics beyond the SM are excluded by our results.

Supplementary Material

Additional plots and tables for use by CMS members in talks can be found here (protected).

Plots/Tables from the Paper (click on plot to get .pdf, all plots also available at https://sus-10-007.web.cern.ch/SUS-10-007/ )

Figure Abbreviated Caption
datamc_LM1.png Figure 1: Distributions of (a) scalar sum of jet transverse energies HT, (b) y = MET/sqrt(HT), (c) dilepton invariant mass M(ll), and (d) dilepton transverse momentum pT(ll) for SM MC and data after preselection. The last bin contains the overflow. Here tt -> l+l- corresponds to dilepton tt, including t -> W -> tau -> l, tt->other includes all other tt decay modes, and VV indicates the sum of WW, WZ, and ZZ. The MC distributions for the LM1 benchmark points are also stacked.
abcd.png Figure 2: Distributions of y vs. HT for SM MC (2-dimensional histogram) and data (scatter plot). Here we also show our choice of ABCD regions
victory_signal.png Figure 3a: Distributions of y (observed) and pT(ll)/sqrt(HT) scaled by the correction factor K50 (predicted) for (a) the signal region and (b) the control region A, for both MC and data. The vertical dashed line indicates the signal region requirement y > 8.5 sqrt(GeV). The deficit at low y is due to the MET > 50 GeV preselection requirement.
victory_control.png Figure 3b: Distributions of y (observed) and pT(ll)/sqrt(HT) scaled by the correction factor K50 (predicted) for (a) the signal region and (b) the control region A, for both MC and data. The vertical dashed line indicates the signal region requirement y > 8.5 sqrt(GeV). The deficit at low y is due to the MET > 50 GeV preselection requirement.
RA6_ExclusionLimit_tanb3_LO.png Figure 4: The observed 95% CL exclusion contour at LO (blue dashed line) and NLO (solid red line) in the CMSSM (m0,m1/2) plane for tan(beta)=3, A0 = 0 and sign of mu > 0. The measured LO exclusion contour is shown as well (dashed blue line). The area below the curve is excluded by this measurement. Exclusion limits obtained from previous experiments are presented as filled areas in the plot. Grey lines correspond to constant squark and gluino masses.
table1.png Table 1: Data yields and MC predictions after preselection, assuming the quoted NLO production cross sections (sigma). The tt -> l+l- corresponds to dilepton tt, including t -> W -> tau -> l, tt -> other includes all other tt decay modes. The samples of MC tt, W + jets, and single-top events were generated with MADGRAPH. The Drell Yan sample (which includes events with invariant masses as low as 10 GeV) was generated using a mixture of MADGRAPH and PYTHIA. All other samples were generated with PYTHIA. The LM0 and LM1 benchmark scenarios are defined in the text. Uncertainties are statistical only.
table2.png Table 2: Data yields in the four regions of Fig. 2, as well as the predicted yield in region D given by NA X NC / NB. We also show the SM and BSM MC expectations. The quoted uncertainties are statistical only.
table3.png Table 3: Number of predicted and observed ee and mumu events in the control region, defined as: 100 < HT < 350 GeV and MET > 80 GeV. "SM MC'' indicates the sum of all MC samples (tt, DY, W+jets, and WW/WZ/ZZ) and includes statistical uncertainties only.
table4.png Table 4: Number of predicted and observed events in the signal region, defined as: HT > 350 GeV and MET> 150 GeV. "SM MC'' indicates the sum of all MC samples (tt, DY, W+jets, and WW/WZ/ZZ) and includes statistical uncertainties only.

-- BenHooberman - 16-Feb-2011

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf HTTrigger.pdf r1 manage 21.0 K 2011-02-22 - 14:27 NiklasMohr  
PNGpng HTTrigger.png r1 manage 15.6 K 2011-02-22 - 14:27 NiklasMohr  
PDFpdf RA6_ExclusionLimit_tanb10.pdf r1 manage 20.8 K 2011-02-16 - 17:12 BenHooberman Exclusion contour in CMSSM parameter space (tanbeta=10)
PNGpng RA6_ExclusionLimit_tanb10.png r1 manage 27.7 K 2011-02-17 - 13:07 BenHooberman Exclusion contour in CMSSM parameter space (tanbeta=10)
PDFpdf RA6_ExclusionLimit_tanb3_LO.pdf r1 manage 22.9 K 2011-02-16 - 17:01 BenHooberman Exclusion contour in CMSSM parameter space
PNGpng RA6_ExclusionLimit_tanb3_LO.png r1 manage 29.7 K 2011-02-17 - 13:05 BenHooberman Exclusion contour in CMSSM parameter space (tanbeta=3)
PDFpdf Scan_OFOSTanBeta10_Pretty.pdf r1 manage 25.3 K 2011-02-21 - 11:11 NiklasMohr  
PNGpng Scan_OFOSTanBeta10_Pretty.png r1 manage 32.1 K 2011-02-21 - 11:12 NiklasMohr  
PDFpdf Scan_OFOSTanBeta3_Pretty.pdf r1 manage 24.9 K 2011-02-21 - 11:10 NiklasMohr  
PNGpng Scan_OFOSTanBeta3_Pretty.png r1 manage 32.7 K 2011-02-21 - 11:11 NiklasMohr  
PDFpdf datamc.pdf r1 manage 282.5 K 2011-02-17 - 13:02 BenHooberman Data/MC comparisons
PDFpdf table_control.pdf r1 manage 47.2 K 2011-02-21 - 11:19 NiklasMohr  
PDFpdf table_signal.pdf r1 manage 72.7 K 2011-02-21 - 11:19 NiklasMohr  
Edit | Attach | Watch | Print version | History: r17 < r16 < r15 < r14 < r13 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r17 - 2011-03-09 - BenHooberman
 
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    CMSPublic All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright & 2008-2019 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback