Search for physics beyond the standard model in events with a Z boson, jets and missing transverse energy

Link to online version

The paper has been published in Physics Letters B, Volume 716, Issue 2, 19 September 2012, Pages 260-284. It is available on this sciencedirect page.

Abstract

A search is presented for physics beyond the standard model (BSM) in events with a Z boson, jets, and missing transverse energy (ETmiss). This signature is motivated by BSM physics scenarios, including supersymmetry. The study is performed using a sample of proton-proton collision data collected at √s = 7 TeV with the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.98 fb−1. The contributions from the dominant standard model backgrounds are estimated from data using two complementary strategies, the jet-Z balance technique and a method based on modeling ETmiss with data control samples. In the absence of evidence for BSM physics, we set limits on the non-standard-model contributions to event yields in the signal regions and interpret the results in the context of simplified model spectra. Additional information is provided to facilitate tests of other BSM physics models.

Approved Plots ( click on plot to get .pdf )

Figure Abbreviated Caption
click on it to get it Di-electron mass distribution for events passing the pre-selection (2 jets, 2 same-flavor opposite-sign leptons). Backgrounds from single top and W +jets are omitted since they are negligible.
This plot compares distributions in data and Monte Carlo simulation; observed discrepancies arise due to incomplete modeling of resolutions, e.g., due to pile-up interactions. The backgrounds for the search are predicted from data as shown in other figures.
click on it to get it Di-muon mass distribution for events passing the pre-selection (2 jets, 2 same-flavor opposite-sign leptons). Backgrounds from single top and W +jets are omitted since they are negligible.
This plot compares distributions in data and Monte Carlo simulation; observed discrepancies arise due to incomplete modeling of resolutions, e.g., due to pile-up interactions. The backgrounds for the search are predicted from data as shown in other figures.
click on it to get it Data and Monte Carlo yields for the di-lepton preselection with Njets ≥ 2.
click on it to get it Data and Monte Carlo yields for the di-lepton preselection with Njets ≥ 3.
click on it to get it Comparison between true and predicted JZB distributions in simulated samples for the background-only hypothesis. The lower plots show the ratio between true and predicted distributions.
click on it to get it Comparison between true and predicted JZB distributions in simulated samples for the LM4-plus-background hypothesis. "MC B" and "MC S" denote the background and signal contributions to the true distribution, respectively. The lower plots show the ratio between true and predicted distributions.
click on it to get it Comparison between true and predicted JZB event yields in SM MC simulation for the various search regions. Uncertainties on the true MC yields reflect the limited MC statistics. The first (second) uncertainty in the MC component.
click on it to get it Comparison between the measured JZB distribution in the JZB > 0 region and that predicted from data control samples. The distribution from the LM4 MC is overlaid. The bottom plot shows the ratio between the observed and predicted distributions. The error bars indicate the statistical uncertainties in data only.
click on it to get it Total number of events observed in the JZB search regions and corresponding background predictions. The first uncertainty is statistical and the second systematic. For the observed yield, the first (second) number in parentheses is the yield in the e+e-+μ-) final state. The 95% CL upper limit (UL) on non-SM yield and the NLO yields for the LM4 and LM8 benchmark SUSY scenarios are also indicated. The contribution of LM4 and LM8 to the background control regions is taken into account in these yields.
click on it to get it The observed missing ET distribution for events with Njets ≥ 2 for data (black points), predicted opposite-flavor background from MC normalized to the eμ yield in data (solid green histogram), WZ + ZZ background (solid purple histogram) and total background including the Z + jets predicted from γ + jets (red line) and QCD (blue line) missing ET templates. The ratio of observed yield to predicted background (data/pred) is indicated using the total background predicted from γ + jets Emiss templates, and the error bars indicate the statistical uncertainty in data only.
click on it to get it Summary of results in the regions missing ET > 30, 60, 100, 200 and 300 GeV, for Njets ≥ 2. The total predicted background (total bkg) is the sum of the Z + jets background predicted from the γ + jets missing ET templates method (Z bkg), the flavor-symmetric background predicted from opposite-flavor events (OF bkg), and the WZ + ZZ background predicted from MC (VZ bkg). The uncertainties include both the statistical and systematic contributions. For the observed yield (data), the first (second) number in parentheses is the yield in the ee (μμ) final state. The 95% CL upper limit on the non-SM yield is indicated, using the average of the background predictions from the QCD and γ + jets templates methods and assessing half the difference between the 2 methods as an additional systematic uncertainty. The expected NLO yields for the LM4 and LM8 benchmark SUSY scenarios are indicated, including the uncertainties from lepton identification and isolation efficiency, trigger efficiency, hadronic energy scale, integrated luminosity, and MC statistics. These LM4 and LM8 yields have been corrected for the impact of signal contamination.
click on it to get it The observed missing ET distribution for events with Njets ≥ 3 for data (black points), predicted opposite-flavor background from MC normalized to the eμ yield in data (solid green histogram), WZ + ZZ background (solid purple histogram) and total background including the Z + jets predicted from γ + jets (red line) and QCD (blue line) missing ET templates. The ratio of observed yield to predicted background (data/pred) is indicated using the average of the two total background predictions from γ + jets and QCD Emiss templates, and the error bars indicate the statistical uncertainty in data only.
click on it to get it Summary of results in the regions missing ET > 30, 60, 100, 200 and 300 GeV, for Njets ≥ 3. The total predicted background (total bkg) is the sum of the Z + jets background predicted from the missing ET templates method (Z bkg), the flavor-symmetric background predicted from opposite-flavor events (OF bkg), and the WZ + ZZ background predicted from MC (VZ bkg). The Z + jets and total background predictions are quoted separately for the QCD and γ + jets missing ET templates. The uncertainties include both the statistical and systematic contributions. For the observed yield (data), the first (second) number in parentheses is the yield in the ee (μμ) final state. The 95% CL upper limit on the non-SM yield is indicated, using the average of the background predictions from the QCD and γ + jets templates methods. The expected NLO yields for the LM4 and LM8 benchmark SUSY scenarios are indicated, including the uncertain- ties from lepton identification and isolation efficiency, trigger efficiency, hadronic energy scale, integrated luminosity, and MC statistics.
click on it to get it Summary of results in the exclusive missing ET bins 100-200, 200-300 GeV, and >300 GeV for Njets ≥ 2 used for the SMS exclusions. The total predicted background (total bkg) is the sum of the Z + jets background predicted from the γ + jets missing ET templates method (Z bkg), the flavor-symmetric background predicted from opposite-flavor events (OF bkg), and the WZ + ZZ background predicted from MC (VZ bkg). The uncertainties include both the statistical and systematic contributions. For the observed yield (data), the first (second) number in parentheses is the yield in the ee (μμ) final state.
click on it to get it JZB distribution in Z+jets, top-antitop and signal MC simulation.
click on it to get it Simplified model for the production of two gluinos decaying into a Z boson, neutralino and jets.
click on it to get it click on it to get it Limits on a neutralino LSP scenario with the JZB method: (left) signal efficiency, including acceptance, in the (mgluino,mneutralino) parameter space for the JZB>150 GeV region, normalized to the number of events with at least one leptonically decaying Z; (right) 95% CL upper limits on the cross section of the inclusive Z boson decay mode. The contribution from signal to the control regions is taken into account.
click on it to get it Parameters of the JZB (top) and missing ET (bottom) response function. The parameter σ is the resolution, xthresh is the JZB or missing ET value at the centre of the efficiency curve and εplateau is the efficiency on the plateau.
click on it to get it Limits on a neutralino LSP scenario with the MET method: (left) signal efficiency, including acceptance, in the (mgluino,mneutralino) parameter space for the MET>100 GeV region, normalized to the number of events with at least one leptonically decaying Z; (right) 95% CL upper limits on the cross section of the inclusive Z boson decay mode. The contribution from signal to the control regions is negligible.
click on it to get it Reconstructed JZB selection efficiency as a function of the generator-level quantity, for the different search regions in LM4 simulation.
click on it to get it Reconstructed MET selection efficiency as a function of the generator-level quantity, for the different search regions in LM4 simulation.
click on it to get itclick on it to get it Limits on a neutralino LSP scenario (x=0.75) with the JZB method: (left) signal efficiency, including acceptance, in the (mgluino,mneutralino) parameter space for the JZB>150 GeV region, normalized to the number of events with at least one leptonically decaying Z; (right) 95% CL upper limits on the cross section of the inclusive Z boson decay mode. The contribution from signal to the control regions is taken into account.
click on it to get it Limits on a neutralino LSP scenario (x=0.25) with the MET method: (left) signal efficiency, including acceptance, in the (mgluino,mneutralino) parameter space for the MET>100 GeV region, normalized to the number of events with at least one leptonically decaying Z; (right) 95% CL upper limits on the cross section of the inclusive Z boson decay mode. The contribution from signal to the control regions is negligible.
click on it to get itclick on it to get it Limits on a neutralino LSP scenario (x=0.25) with the JZB method: (left) signal efficiency, including acceptance, in the (mgluino,mneutralino) parameter space for the JZB>150 GeV region, normalized to the number of events with at least one leptonically decaying Z; (right) 95% CL upper limits on the cross section of the inclusive Z boson decay mode. The contribution from signal to the control regions is taken into account.
click on it to get it Limits on a neutralino LSP scenario (x=0.75) with the MET method: (left) signal efficiency, including acceptance, in the (mgluino,mneutralino) parameter space for the MET>100 GeV region, normalized to the number of events with at least one leptonically decaying Z; (right) 95% CL upper limits on the cross section of the inclusive Z boson decay mode. The contribution from signal to the control regions is negligible.
click on it to get itclick on it to get it Limits on a gravitino LSP scenario with the JZB method: (left) signal efficiency, including acceptance, in the (mgluino,mneutralino) parameter space for the JZB>150 GeV region, normalized to the number of events with at least one leptonically decaying Z; (right) 95% CL upper limits on the cross section of the inclusive Z boson decay mode. The contribution from signal to the control regions is taken into account.
click on it to get it Limits on a gravitino LSP scenario with the MET method: (left) signal efficiency, including acceptance, in the (mgluino,mneutralino) parameter space for the MET>100 GeV region, normalized to the number of events with at least one leptonically decaying Z ; (right) 95% CL upper limits on the cross section of the inclusive Z boson decay mode. The contribution from signal to the control regions is negligible.
click on it to get it Limits on a gravitino LSP scenario with the MET method. The upper limits on the cross section vs. gluino mass are plotted for three choices for the mass of the lightest neutralino, and compared to the predicted cross section computed at NLO. This plot contains the same information as the above MET templates gravitino LSP exclusion in the (mgluino,mneutralino) parameter space; here, the results are projected onto the mgluino axis

Links to documentation in CDS

-- FredericRonga - 30-Jan-2012

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf SMS_T5zz_2jets.pdf r4 r3 r2 r1 manage 40.6 K 2012-05-03 - 14:34 BenHooberman  
PNGpng SMS_T5zz_2jets.png r7 r6 r5 r4 r3 manage 164.8 K 2012-05-03 - 14:34 BenHooberman  
PDFpdf SMS_T5zzgmsb_2jets.pdf r6 r5 r4 r3 r2 manage 40.4 K 2012-05-03 - 14:34 BenHooberman  
PNGpng SMS_T5zzgmsb_2jets.png r6 r5 r4 r3 r2 manage 169.2 K 2012-05-03 - 14:35 BenHooberman  
PDFpdf SMS_T5zzh.pdf r1 manage 40.2 K 2012-05-03 - 14:40 BenHooberman  
PNGpng SMS_T5zzh.png r2 r1 manage 161.6 K 2012-05-03 - 14:40 BenHooberman  
PDFpdf SMS_T5zzl_2jets.pdf r6 r5 r4 r3 r2 manage 40.3 K 2012-05-03 - 14:35 BenHooberman  
PNGpng SMS_T5zzl_2jets.png r6 r5 r4 r3 r2 manage 166.9 K 2012-05-03 - 14:36 BenHooberman  
PDFpdf T5zz.pdf r2 r1 manage 42.8 K 2012-03-09 - 20:49 BenHooberman  
PNGpng T5zz.png r3 r2 r1 manage 43.7 K 2012-03-09 - 20:50 BenHooberman  
PDFpdf final_exclusion_T5zzh.pdf r1 manage 27.7 K 2012-05-03 - 14:53 MariarosariaDalfonso  
PNGpng final_exclusion_T5zzh.png r1 manage 428.1 K 2012-05-03 - 14:32 MariarosariaDalfonso  
PDFpdf hdilmass_ee_allj.pdf r3 r2 r1 manage 12.0 K 2012-05-04 - 21:55 UnknownUser  
PNGpng hdilmass_ee_allj.png r3 r2 r1 manage 14.0 K 2012-05-04 - 21:56 UnknownUser  
PDFpdf hdilmass_mm_allj.pdf r3 r2 r1 manage 12.0 K 2012-05-04 - 21:56 UnknownUser  
PNGpng hdilmass_mm_allj.png r3 r2 r1 manage 13.9 K 2012-05-04 - 21:56 UnknownUser  
PDFpdf jzb_Bpred_Data_Composition_withratio.pdf r2 r1 manage 19.5 K 2012-04-30 - 16:35 FredericRonga  
PNGpng jzb_Bpred_Data_Composition_withratio.png r2 r1 manage 122.6 K 2012-04-30 - 16:36 FredericRonga  
PDFpdf jzb_Bpred_MC_withratio.pdf r2 r1 manage 17.8 K 2012-04-30 - 16:44 FredericRonga  
PNGpng jzb_Bpred_MC_withratio.png r3 r2 r1 manage 107.4 K 2012-04-30 - 16:45 FredericRonga  
PDFpdf jzb_Bpred_MCwithS__plus_withratio.pdf r2 r1 manage 20.7 K 2012-04-30 - 17:17 FredericRonga  
PNGpng jzb_Bpred_MCwithS__plus_withratio.png r3 r2 r1 manage 142.0 K 2012-04-30 - 17:17 FredericRonga  
PDFpdf jzb_SMS_efficiencymap150_025.pdf r1 manage 28.5 K 2012-05-03 - 14:27 MariarosariaDalfonso  
PNGpng jzb_SMS_efficiencymap150_025.png r1 manage 355.2 K 2012-05-03 - 14:27 MariarosariaDalfonso  
PDFpdf jzb_SMS_efficiencymap150_05.pdf r3 r2 r1 manage 28.3 K 2012-04-30 - 17:24 FredericRonga  
PNGpng jzb_SMS_efficiencymap150_05.png r4 r3 r2 r1 manage 140.8 K 2012-04-30 - 17:24 FredericRonga  
PDFpdf jzb_SMS_efficiencymap150_075.pdf r3 r2 r1 manage 28.4 K 2012-04-30 - 17:24 FredericRonga  
PNGpng jzb_SMS_efficiencymap150_075.png r3 r2 r1 manage 144.9 K 2012-04-30 - 17:25 FredericRonga  
PDFpdf jzb_SMS_efficiencymap150_gmsb.pdf r4 r3 r2 r1 manage 28.6 K 2012-04-30 - 17:25 FredericRonga  
PNGpng jzb_SMS_efficiencymap150_gmsb.png r3 r2 r1 manage 187.7 K 2012-04-30 - 17:25 FredericRonga  
PDFpdf jzb_bg_vs_signal_distribution.pdf r2 r1 manage 16.6 K 2012-04-30 - 17:42 FredericRonga  
PNGpng jzb_bg_vs_signal_distribution.png r2 r1 manage 99.1 K 2012-04-30 - 17:42 FredericRonga  
PDFpdf jzb_efficiency_curveLM4.pdf r2 r1 manage 20.4 K 2012-04-30 - 17:26 FredericRonga  
PNGpng jzb_efficiency_curveLM4.png r3 r2 r1 manage 170.8 K 2012-04-30 - 17:26 FredericRonga  
PDFpdf jzb_final_exclusion__bestlimits_05.pdf r4 r3 r2 r1 manage 27.4 K 2012-04-30 - 17:27 FredericRonga  
PNGpng jzb_final_exclusion__bestlimits_05.png r5 r4 r3 r2 r1 manage 172.3 K 2012-04-30 - 17:27 FredericRonga  
PDFpdf jzb_final_exclusion__bestlimits_075.pdf r4 r3 r2 r1 manage 28.1 K 2012-04-30 - 17:28 FredericRonga  
PNGpng jzb_final_exclusion__bestlimits_075.png r4 r3 r2 r1 manage 178.1 K 2012-04-30 - 17:28 FredericRonga  
PDFpdf jzb_final_exclusion__bestlimits_gmsb.pdf r3 r2 r1 manage 28.6 K 2012-04-30 - 17:28 FredericRonga  
PNGpng jzb_final_exclusion__bestlimits_gmsb.png r4 r3 r2 r1 manage 187.7 K 2012-04-30 - 17:28 FredericRonga  
PDFpdf makePlot.pdf r3 r2 r1 manage 17.1 K 2012-05-03 - 15:03 BenHooberman GMSB exclusion vs. gluino mass for MET templates analysis
PNGpng makePlot.png r3 r2 r1 manage 199.5 K 2012-05-03 - 15:03 BenHooberman  
PDFpdf met_turnon_LM4.pdf r1 manage 20.2 K 2012-01-30 - 11:10 FredericRonga  
PNGpng met_turnon_LM4.png r2 r1 manage 174.8 K 2012-01-30 - 11:32 FredericRonga  
PDFpdf metplot_2jets.pdf r7 r6 r5 r4 r3 manage 26.9 K 2012-05-01 - 23:58 BenHooberman  
PNGpng metplot_2jets.png r8 r7 r6 r5 r4 manage 124.2 K 2012-05-01 - 23:58 BenHooberman  
PDFpdf metplot_3jets.pdf r6 r5 r4 r3 r2 manage 26.8 K 2012-05-03 - 14:32 BenHooberman  
PNGpng metplot_3jets.png r7 r6 r5 r4 r3 manage 131.6 K 2012-05-03 - 14:33 BenHooberman  
PDFpdf table0.pdf r2 r1 manage 89.4 K 2012-04-30 - 17:47 FredericRonga  
PNGpng table0.png r2 r1 manage 29.3 K 2012-04-30 - 17:47 FredericRonga  
PDFpdf table1.pdf r2 r1 manage 91.3 K 2012-04-30 - 17:48 FredericRonga  
PNGpng table1.png r2 r1 manage 48.8 K 2012-04-30 - 17:47 FredericRonga  
PDFpdf table2.pdf r4 r3 r2 r1 manage 72.1 K 2012-05-03 - 14:44 BenHooberman  
PNGpng table2.png r4 r3 r2 r1 manage 72.8 K 2012-05-03 - 14:45 BenHooberman  
PDFpdf table3.pdf r4 r3 r2 r1 manage 95.3 K 2012-05-03 - 14:46 BenHooberman  
PNGpng table3.png r4 r3 r2 r1 manage 98.8 K 2012-05-03 - 14:46 BenHooberman  
PDFpdf table4.pdf r4 r3 r2 r1 manage 39.1 K 2012-05-03 - 14:46 BenHooberman  
PNGpng table4.png r4 r3 r2 r1 manage 38.8 K 2012-05-03 - 14:46 BenHooberman  
PDFpdf table5.pdf r2 r1 manage 131.9 K 2012-04-30 - 17:48 FredericRonga  
PNGpng table5.png r2 r1 manage 40.8 K 2012-04-30 - 17:48 FredericRonga  
PDFpdf table6.pdf r2 r1 manage 42.8 K 2012-05-04 - 22:14 UnknownUser  
PNGpng table6.png r2 r1 manage 87.1 K 2012-05-04 - 22:15 UnknownUser  
PDFpdf table7.pdf r2 r1 manage 42.9 K 2012-05-04 - 22:15 UnknownUser  
PNGpng table7.png r2 r1 manage 78.1 K 2012-05-04 - 22:16 UnknownUser  
Edit | Attach | Watch | Print version | History: r26 < r25 < r24 < r23 < r22 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r26 - 2012-09-13 - FredericRonga
 
    • 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