TOP-11-009
A Search for Resonances in Semileptonic Top Pair Production

Abstract

We present the results of a search for massive neutral bosons decaying via a top- antitop quark pair. The analysis is carried out using 4.7 fb-1 of proton-proton collision data at a centre-of-mass energy of 7 TeV collected by the CMS detector at the LHC during 2011. From a combined analysis of the muon plus jets and electron plus jets decay modes no significant signal is observed, and upper limits on the production cross section as a function of the boson mass in several models are reported.

Public Document

The document CMS-PAS-TOP-11-009 published on the CERN document server will be linked here.

Figures

Reconstructed Mass Distributions in Electron Plus Jets Channel

Figure Caption
electron_mttbar_fit_chi2btags_3j1btags_max_perm.png Reconstructed top pair mass using leading 3 jets in 3-jet events with at least one b tag in the electron + jets channel. The background contributions are scaled according to a background only fit, and the expected signal distributions for narrow topcolor Z' models at a number of different masses are also shown. PDF version
electron_mttbar_fit_chi2btags_4j0btags_max_perm.png Reconstructed top pair mass in 4-jet events with no b tag in the electron + jets channel The background contributions are scaled according to a background only fit, and the expected signal distributions for narrow topcolor Z' models at a number of different masses are also shown.. PDF version
electron_mttbar_fit_chi2btags_4j1btags_max_perm.png Reconstructed top pair mass in 4-jet events with one b tag in the electron + jets channel The background contributions are scaled according to a background only fit, and the expected signal distributions for narrow topcolor Z' models at a number of different masses are also shown.. PDF version
electron_mttbar_fit_chi2btags_4j2btags_max_perm.png Reconstructed top pair mass in 4-jet events with two or more b tags in the electron + jets channel The background contributions are scaled according to a background only fit, and the expected signal distributions for narrow topcolor Z' models at a number of different masses are also shown.. PDF version

Reconstructed Mass Distributions in Muon Plus Jets Channel

Figure Caption
muon_mttbar_fit_chi2btags_3j1btags_max_perm.png Reconstructed top pair mass using leading 3 jets in 3-jet events with at least one b tag in the muon + jets channel. The background contributions are scaled according to a background only fit, and the expected signal distributions for narrow topcolor Z' models at a number of different masses are also shown.. PDF version
muon_mttbar_fit_chi2btags_4j0btags_max_perm.png Reconstructed top pair mass in 4-jet events with no b tag in the muon + jets channel The background contributions are scaled according to a background only fit, and the expected signal distributions for narrow topcolor Z' models at a number of different masses are also shown.. PDF version
muon_mttbar_fit_chi2btags_4j1btags_max_perm.png Reconstructed top pair mass in 4-jet events with one b tag in the muon + jets channel The background contributions are scaled according to a background only fit, and the expected signal distributions for narrow topcolor Z' models at a number of different masses are also shown.. PDF version
muon_mttbar_fit_chi2btags_4j2btags_max_perm.png Reconstructed top pair mass in 4-jet events with two b tags in the muon + jets channel The background contributions are scaled according to a background only fit, and the expected signal distributions for narrow topcolor Z' models at a number of different masses are also shown.. PDF version

Results

Figure Caption
limits_1_higgs.png Expected and observed limits from CLs for σ(pp→ Z')×BR(Z'→tt) for L = 4.7 fb-1 as a function of Z' mass using Z' models with Γ/mZ' = 1%, i.e. for Z' samples fulfilling the narrow-width approximation, including all considered systematic uncertainties. The light grey band indicates the ±1σ band of the expected limits, and the dark grey band the ±2σ band of expected limits. PDF version
limits_1_higgs_log.png Expected and observed limits from CLs for σ(pp→ Z')×BR(Z'→tt) for L = 4.7 fb-1 as a function of Z' mass using Z' models with Γ/mZ' = 1%, i.e. for Z' samples fulfilling the narrow-width approximation, including all considered systematic uncertainties (logarithmic scale). The light grey band indicates the ±1σ band of the expected limits, and the dark grey band the ±2σ band of expected limits. PDF version
limits_10_higgs.png Expected and observed limits from CLs for σ(pp→ Z')×BR(Z'→tt) for L = 4.7 fb-1 as a function of Z' mass using Z' models with Γ/mZ' = 10%, including all considered systematic uncertainties. The light grey band indicates the ±1σ band of the expected limits, and the dark grey band the ±2σ band of expected limits. PDF version
limits_10_higgs_log.png Expected and observed limits from CLs for σ(pp→ Z')×BR(Z'→tt) for L = 4.7 fb-1 as a function of Z' mass using Z' models with Γ/mZ' = 10%, including all considered systematic uncertainties (logarithmic scale). The light grey band indicates the ±1σ band of the expected limits, and the dark grey band the ±2σ band of expected limits. PDF version
limits_kk_higgs.png Expected and observed limits from CLs for σ(pp→ k')×BR(k'→tt) for L = 4.7 fb-1 as a function of KK gluon mass, including all considered systematic uncertainties. The light grey band indicates the ±1σ band of the expected limits, and the dark grey band the ±2σ band of expected limits. PDF version
limits_kk_higgs_log.png Expected and observed limits from CLs for σ(pp→ k')×BR(k'→tt) for L = 4.7 fb-1 as a function of KK gluon mass, including all considered systematic uncertainties (logarithmic scale). The light grey band indicates the ±1σ band of the expected limits, and the dark grey band the ±2σ band of expected limits. PDF version
Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf electron_mttbar_fit_chi2btags_3j1btags_max_perm.pdf r1 manage 21.7 K 2012-02-23 - 23:38 JoelGoldstein Electron + 3 jet 1 b tag (pdf)
PNGpng electron_mttbar_fit_chi2btags_3j1btags_max_perm.png r1 manage 26.0 K 2012-02-23 - 23:37 JoelGoldstein Electron + 3 jet 1 b tag
PDFpdf electron_mttbar_fit_chi2btags_4j0btags_max_perm.pdf r1 manage 21.4 K 2012-02-23 - 23:51 JoelGoldstein  
PNGpng electron_mttbar_fit_chi2btags_4j0btags_max_perm.png r1 manage 25.3 K 2012-02-23 - 23:51 JoelGoldstein  
PDFpdf electron_mttbar_fit_chi2btags_4j1btags_max_perm.pdf r2 r1 manage 22.3 K 2012-02-28 - 16:27 JoelGoldstein  
PNGpng electron_mttbar_fit_chi2btags_4j1btags_max_perm.png r2 r1 manage 24.2 K 2012-02-28 - 16:30 JoelGoldstein  
PDFpdf electron_mttbar_fit_chi2btags_4j2btags_max_perm.pdf r2 r1 manage 20.4 K 2012-02-28 - 16:30 JoelGoldstein  
PNGpng electron_mttbar_fit_chi2btags_4j2btags_max_perm.png r2 r1 manage 23.0 K 2012-02-28 - 16:31 JoelGoldstein  
PDFpdf limits_10_higgs.pdf r1 manage 15.0 K 2012-02-24 - 00:33 JoelGoldstein  
PNGpng limits_10_higgs.png r1 manage 149.0 K 2012-02-24 - 00:33 JoelGoldstein  
PDFpdf limits_10_higgs_log.pdf r1 manage 15.3 K 2012-02-24 - 00:32 JoelGoldstein  
PNGpng limits_10_higgs_log.png r1 manage 149.1 K 2012-02-24 - 00:32 JoelGoldstein  
PDFpdf limits_1_higgs.pdf r1 manage 15.4 K 2012-02-24 - 00:31 JoelGoldstein  
PNGpng limits_1_higgs.png r1 manage 150.8 K 2012-02-24 - 00:31 JoelGoldstein  
PDFpdf limits_1_higgs_log.pdf r1 manage 15.2 K 2012-02-24 - 00:30 JoelGoldstein  
PNGpng limits_1_higgs_log.png r1 manage 146.0 K 2012-02-24 - 00:31 JoelGoldstein  
PDFpdf limits_kk_higgs.pdf r1 manage 15.1 K 2012-02-24 - 00:38 JoelGoldstein  
PNGpng limits_kk_higgs.png r1 manage 140.1 K 2012-02-24 - 00:38 JoelGoldstein  
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PDFpdf muon_mttbar_fit_chi2btags_3j1btags_max_perm.pdf r1 manage 22.0 K 2012-02-23 - 23:54 JoelGoldstein  
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Topic revision: r8 - 2012-03-03 - RobertoTenchini
 
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