Search for single top tW associated production in the dilepton decay channel in pp collisions at √s=7 TeV

Main document TOP-11-022

Abstract

This paper describes the first study of the single top W-associated production (tW) carried out with the CMS experiment in 7 TeV proton-proton collisions using an in- tegrated luminosity of 2.1 fb−1, recorded during the first data-taking period of 2011. The search is performed in the dileptonic final states with a selection based on kinematical properties and b-tag information. The contribution of the Z+jets processes to the background is estimated with a data driven method. Two ttbar dominated control regions are defined to constrain the ttbar normalization in the signal region. An excess of events over the expected background is observed with a significance of is observed with a significance of 2.7σ, while the expected significance of the tW signal is 1.8 +- 0.9 σ. Assigning the excess to events from tW production the extracted cross section, 22 +9 -7(stat.+sys.) pb, is in agreement with the standard model expectation.

Approved plots from TOP-11-022 ( click on plot to get .pdf )

general caption
fgSTtWfirst.pdf fgSTtWfirst.pdf Figure 1 : Feynman diagrams at Leading Order (LO) for single top production in the tW mode.
Wt-production_glubox.pdf Wt-production_glufus.pdfWt-production_qqbar.pdf Figure 2 : Feynman diagrams at Next-to-Leading Order (NLO) for single top production in the tW mode that mix with tt and that are removed from the signal definition in the DR simulation scheme.
norm_0_ptsys_bf.pdf norm_0_ht_bf.pdf Figure 3 : Kinematic distributions normalized to the same area in the eμ final state for simulated tW signal, tt background and the sum of other backgrounds after lepton selection and lepton veto, in events with exactly one jet.
plot_0_ptsys.pdf plot_1_ptsys.pdf plot_2_ptsys.pdf plot_3_ptsys.pdf Figure 4 : PTsystem distributions in data and simulation after full selection minus the requirements on these two variables, in the ee, eμ and μμ final states, separately and all together.
plot_0_ht.pdf plot_1_ht.pdf plot_2_ht.pdf plot_3_ht.pdf Figure 5 : HT distributions in data and simulation after full selection minus the requirements on these two variables, in the ee, eμ and μμ final states, separately and all together.
controlttdytt_0_R.pdf controlttdytt_1_R.pdf controlttdytt_2_R.pdf controlttdytt_3_R.pdf Figure 6 : Event yields in data and simulation in the signal region (1 jet, 1 tag) and the two tt-enriched control regions for the three final states. The Drell-Yan contribution to the signal region is estimated from data and the tt contribution is scaled to the outcome of the statistical fit.

Event Displays from 2011 Data

Figure Caption
Single top tW channel candidate di-muon + b-jet + MET PDF
Single top tW channel candidate di-electron + b-jet + MET PDF
Single top tW channel candidate electron + muon + b-jet + MET PDF

-- RebecaGonzalezSuarez - 22-Sep-2011

Topic attachments
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PDFpdf Wt-production_glubox.pdf r1 manage 11.6 K 2011-09-23 - 15:22 RebecaGonzalezSuarez  
PNGpng Wt-production_glubox.png r1 manage 4.8 K 2011-09-23 - 15:23 RebecaGonzalezSuarez  
PDFpdf Wt-production_glufus.pdf r1 manage 11.7 K 2011-09-23 - 15:22 RebecaGonzalezSuarez  
PNGpng Wt-production_glufus.png r1 manage 5.1 K 2011-09-23 - 15:23 RebecaGonzalezSuarez  
PDFpdf Wt-production_qqbar.pdf r1 manage 9.4 K 2011-09-23 - 15:23 RebecaGonzalezSuarez  
PNGpng Wt-production_qqbar.png r1 manage 4.6 K 2011-09-23 - 15:23 RebecaGonzalezSuarez  
PDFpdf controlttdytt_0_R.pdf r1 manage 14.0 K 2011-09-23 - 15:31 RebecaGonzalezSuarez  
PNGpng controlttdytt_0_R.png r1 manage 13.0 K 2011-09-23 - 15:31 RebecaGonzalezSuarez  
PDFpdf controlttdytt_1_R.pdf r1 manage 14.1 K 2011-09-23 - 15:32 RebecaGonzalezSuarez  
PNGpng controlttdytt_1_R.png r1 manage 12.9 K 2011-09-23 - 15:32 RebecaGonzalezSuarez  
PDFpdf controlttdytt_2_R.pdf r1 manage 14.1 K 2011-09-23 - 15:33 RebecaGonzalezSuarez  
PNGpng controlttdytt_2_R.png r1 manage 13.5 K 2011-09-23 - 15:33 RebecaGonzalezSuarez  
PDFpdf controlttdytt_3_R.pdf r1 manage 13.8 K 2011-09-23 - 15:33 RebecaGonzalezSuarez  
PNGpng controlttdytt_3_R.png r1 manage 11.9 K 2011-09-23 - 15:33 RebecaGonzalezSuarez  
PDFpdf fgSTtWfirst.pdf r1 manage 6.6 K 2011-09-23 - 15:22 RebecaGonzalezSuarez  
PNGpng fgSTtWfirst.png r1 manage 2.7 K 2011-09-23 - 15:21 RebecaGonzalezSuarez  
PDFpdf fgSTtWsecond.pdf r1 manage 6.4 K 2011-09-23 - 15:22 RebecaGonzalezSuarez  
PNGpng fgSTtWsecond.png r1 manage 2.8 K 2011-09-23 - 15:22 RebecaGonzalezSuarez  
PDFpdf norm_0_ht_bf.pdf r1 manage 14.7 K 2011-09-23 - 15:25 RebecaGonzalezSuarez  
PNGpng norm_0_ht_bf.png r1 manage 14.8 K 2011-09-23 - 15:25 RebecaGonzalezSuarez  
PDFpdf norm_0_ptsys_bf.pdf r1 manage 14.6 K 2011-09-23 - 15:24 RebecaGonzalezSuarez  
PNGpng norm_0_ptsys_bf.png r1 manage 13.7 K 2011-09-23 - 15:24 RebecaGonzalezSuarez  
PDFpdf plot_0_ht.pdf r1 manage 15.7 K 2011-09-23 - 15:26 RebecaGonzalezSuarez  
PNGpng plot_0_ht.png r1 manage 16.4 K 2011-09-23 - 15:26 RebecaGonzalezSuarez  
PDFpdf plot_0_ptsys.pdf r1 manage 16.0 K 2011-09-23 - 15:26 RebecaGonzalezSuarez  
PNGpng plot_0_ptsys.png r1 manage 17.4 K 2011-09-23 - 15:27 RebecaGonzalezSuarez  
PDFpdf plot_1_ht.pdf r1 manage 15.7 K 2011-09-23 - 15:27 RebecaGonzalezSuarez  
PNGpng plot_1_ht.png r1 manage 16.1 K 2011-09-23 - 15:27 RebecaGonzalezSuarez  
PDFpdf plot_1_ptsys.pdf r1 manage 15.9 K 2011-09-23 - 15:28 RebecaGonzalezSuarez  
PNGpng plot_1_ptsys.png r1 manage 16.4 K 2011-09-23 - 15:28 RebecaGonzalezSuarez  
PDFpdf plot_2_ht.pdf r1 manage 15.7 K 2011-09-23 - 15:28 RebecaGonzalezSuarez  
PNGpng plot_2_ht.png r1 manage 16.4 K 2011-09-23 - 15:29 RebecaGonzalezSuarez  
PDFpdf plot_2_ptsys.pdf r1 manage 15.9 K 2011-09-23 - 15:29 RebecaGonzalezSuarez  
PNGpng plot_2_ptsys.png r1 manage 17.1 K 2011-09-23 - 15:29 RebecaGonzalezSuarez  
PDFpdf plot_3_ht.pdf r1 manage 15.8 K 2011-09-23 - 15:30 RebecaGonzalezSuarez  
PNGpng plot_3_ht.png r1 manage 13.6 K 2011-09-23 - 15:30 RebecaGonzalezSuarez  
PDFpdf plot_3_ptsys.pdf r1 manage 16.1 K 2011-09-23 - 15:30 RebecaGonzalezSuarez  
PNGpng plot_3_ptsys.png r1 manage 14.4 K 2011-09-23 - 15:30 RebecaGonzalezSuarez  
PDFpdf tWCandidates_eecandidate.pdf r1 manage 97.6 K 2011-11-28 - 12:06 RebecaGonzalezSuarez  
PNGpng tWCandidates_eecandidate.png r1 manage 1004.3 K 2011-11-28 - 12:05 RebecaGonzalezSuarez  
PDFpdf tWCandidates_emucandidate.pdf r1 manage 91.1 K 2011-11-28 - 12:06 RebecaGonzalezSuarez  
PNGpng tWCandidates_emucandidate.png r1 manage 868.9 K 2011-11-28 - 12:05 RebecaGonzalezSuarez  
PDFpdf tWCandidates_mumucandidate.pdf r1 manage 97.2 K 2011-11-28 - 12:05 RebecaGonzalezSuarez  
PNGpng tWCandidates_mumucandidate.png r1 manage 980.4 K 2011-11-28 - 12:04 RebecaGonzalezSuarez  
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