SUS-11-017 : Search for New Physics in Events with a Z Boson and Missing Transverse Energy

Link to Physics Analysis Summary (PAS)

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Abstract

We search for new physics in the dilepton final state of Z plus two or more jets plus missing transverse energy (MET). The search is performed using LHC data at a center of mass energy √s=7 TeV recorded by the CMS detector corresponding to an integrated luminosity of 0.98 / fb The Z boson is reconstructed in its decay to e+e- or mu+mu-, and the signal regions are defined using requirements of large MET. We use data driven techniques to predict the standard model backgrounds. No evidence for an excess in the signal regions is observed, and the results are used to place upper limits on the non-SM contributions to the yields in the signal regions and to make model dependent limits on benchmark new physics scenarios. Additional information is provided to allow testing whether specific models of new physics are excluded by these results.

Approved Plots from SUS-11-017

Figure Abbreviated Caption
hdilmass_ee_allj.png Dilepton mass distribution for e-e events passing the preselection.
hdilmass_em_allj.png Dilepton mass distribution for e-mu events passing the preselection.
hdilmass_mm_allj.png Dilepton mass distribution for mu-mu events passing the preselection.
hdilmass_pfmet100_ee_allj.png Dilepton mass distribution for e-e events passing the preselection and MET > 100.
hdilmass_pfmet100_em_allj.png Dilepton mass distribution for e-mu events passing the preselection and MET > 100.
hdilmass_pfmet100_mm_allj.png Dilepton mass distribution for mu-mu events passing the preselection and MET > 100.
hdilmet_em_allj.png MET distribution for the e-mu final state passing preselection.
lep_metPredicted.png The observed MET distribution for data (black points), predicted t-tbar MET distribution (red line), and the sum of predicted t-tbar MET distribution and Z MET distribution (blue line) for all events.
lep_metPredicted_ee.png The observed MET distribution for data (black points), predicted t-tbar MET distribution (red line), and the sum of predicted t-tbar MET distribution and Z MET distribution (blue line) for e-e events.
lep_metPredicted_mm.png The observed MET distribution for data (black points), predicted t-tbar MET distribution (red line), and the sum of predicted t-tbar MET distribution and Z MET distribution (blue line) for mu-mu events.
mcclosure.png The MET distribution in Z plus jets MC (black) and prediction (blue) for Njet >= 2.
phoqcd_predcomp_all_nodata.png The predicted MET distribution from QCD templates (blue) and photon plus jets templates (red).

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: T5zz_met.root . Signal contamination in control regions has not been taken into account when computing the upper limits on the production cross sections.

Figure Abbreviated Caption
Simplified model topology "T5zz". m(chi20)=0.5*(mGL+MLSP). The Z decays "naturally".
Signal efficiencies for T5zz, for the "low MET" selection. Efficiency normalized to events that contain at least one Z to leptons.
Signal efficiencies for T5zz, for the "high MET" selection. Efficiency normalized to events that contain at least one Z to leptons.
Upper limit on production cross section, for T5zz, assuming a branching ratio of 1. For each point, the result of the "best" selection (i.e. the minimal value for the upper limit) is taken. Superimposed are 95% CL exclusion contours, assuming a "reference SUSY cross section", for decoupled squarks: m(~q)>>m(~g).

-- WarrenAndrews - 22-Jul-2011

Topic attachments
I Attachment History Action Size Date Who Comment
Unknown file formatroot T5zz_met.root r1 manage 19.4 K 2011-09-13 - 14:11 MariarosariaDalfonso  
PDFpdf comparison_T5zz_warren_xSec.pdf r1 manage 15.7 K 2011-09-30 - 12:35 Walten  
PNGpng comparison_T5zz_warren_xSec.png r1 manage 42.9 K 2011-09-30 - 12:35 Walten  
PDFpdf h_eff_T5zz_warren_100.pdf r1 manage 15.0 K 2011-09-30 - 12:34 Walten  
PNGpng h_eff_T5zz_warren_100.png r1 manage 11.1 K 2011-09-30 - 12:34 Walten  
PDFpdf h_eff_T5zz_warren_200.pdf r1 manage 14.9 K 2011-09-30 - 12:35 Walten  
PNGpng h_eff_T5zz_warren_200.png r1 manage 11.1 K 2011-09-30 - 12:35 Walten  
PDFpdf hdilmass_ee_allj.pdf r1 manage 14.5 K 2011-07-22 - 16:32 UnknownUser  
PNGpng hdilmass_ee_allj.png r1 manage 15.4 K 2011-07-22 - 16:33 UnknownUser  
PDFpdf hdilmass_em_allj.pdf r1 manage 9.0 K 2011-07-22 - 16:34 UnknownUser  
PNGpng hdilmass_em_allj.png r1 manage 14.2 K 2011-07-22 - 16:34 UnknownUser  
PDFpdf hdilmass_mm_allj.pdf r1 manage 20.8 K 2011-07-22 - 16:34 UnknownUser  
PNGpng hdilmass_mm_allj.png r1 manage 15.1 K 2011-07-22 - 16:35 UnknownUser  
PDFpdf hdilmass_pfmet100_ee_allj.pdf r1 manage 6.8 K 2011-07-22 - 16:35 UnknownUser  
PNGpng hdilmass_pfmet100_ee_allj.png r1 manage 13.1 K 2011-07-22 - 16:35 UnknownUser  
PDFpdf hdilmass_pfmet100_em_allj.pdf r1 manage 7.1 K 2011-07-22 - 16:35 UnknownUser  
PNGpng hdilmass_pfmet100_em_allj.png r1 manage 14.6 K 2011-07-22 - 16:35 UnknownUser  
PDFpdf hdilmass_pfmet100_mm_allj.pdf r1 manage 6.9 K 2011-07-22 - 16:36 UnknownUser  
PNGpng hdilmass_pfmet100_mm_allj.png r1 manage 13.2 K 2011-07-22 - 16:36 UnknownUser  
PDFpdf hdilmet_em_allj.pdf r1 manage 6.7 K 2011-07-22 - 16:36 UnknownUser  
PNGpng hdilmet_em_allj.png r1 manage 13.9 K 2011-07-22 - 16:36 UnknownUser  
PDFpdf lep_metPredicted.pdf r1 manage 10.4 K 2011-07-22 - 16:37 UnknownUser  
PNGpng lep_metPredicted.png r1 manage 15.5 K 2011-07-22 - 16:37 UnknownUser  
PDFpdf lep_metPredicted_ee.pdf r1 manage 9.4 K 2011-07-22 - 16:37 UnknownUser  
PNGpng lep_metPredicted_ee.png r1 manage 15.1 K 2011-07-22 - 16:37 UnknownUser  
PDFpdf lep_metPredicted_mm.pdf r1 manage 10.1 K 2011-07-22 - 16:38 UnknownUser  
PNGpng lep_metPredicted_mm.png r1 manage 15.3 K 2011-07-22 - 16:38 UnknownUser  
PDFpdf mcclosure.pdf r1 manage 11.6 K 2011-07-22 - 16:38 UnknownUser  
PNGpng mcclosure.png r1 manage 10.2 K 2011-07-22 - 16:38 UnknownUser  
PDFpdf phoqcd_predcomp_all_nodata.pdf r1 manage 14.2 K 2011-07-22 - 16:39 UnknownUser  
PNGpng phoqcd_predcomp_all_nodata.png r1 manage 11.3 K 2011-07-22 - 16:39 UnknownUser  
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Topic revision: r6 - 2011-09-30 - Walten
 
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