Measurement of the top-quark pair-production cross section in the lepton+jets channel with the use of b-tagging

Abstract

We present a new measurement of the production cross section for pp → ttbar, at a center-of-mass energy of 7 TeV using data collected by the CMS detector at the Large Hadron Collider. The analysis uses an integrated luminosity of 36 pb−1 of data, and is based on the final state with one isolated, high transverse momentum muon or electron, missing transverse energy and hadronic jets. The ttbar content of the data has been enhanced by requiring the presence of at least one jet consistent with originating from b-quark production. The measured cross section is 150 ± 9 (stat.) ± 17 (syst.) ± 6 (lumi.) pb.

Approved Results from TOP-10-003 ( click on result to get .jpeg )

Result	Channel
	Fitted ttbar cross section for the electron+jets channel
	Fitted ttbar cross section for the muon+jets channel
	Fitted ttbar cross section for the combined electron+jets and muon+jets channel

Approved Plots from TOP-10-003 ( click on plot to get .pdf )

Figure	Abbreviated Caption
	Secondary vertex mass templates used in profile likelihood fit. PNG
	Legend for profile likelihood fit plots. PNG
	Fitted vertex mass in 1-tag events in the muon channel. PNG
	Fitted vertex mass in 1-tag events in the electron channel. PNG
	Fitted vertex mass in 2-tag events in the muon channel. PNG
	Fitted vertex mass in 2-tag events in the electron channel. PNG
	Scalar sum of transverse energies in the muon channel. PNG
	Scalar sum of transverse energies in the electron channel. PNG
	W transverse mass in the muon channel. PNG
	W transverse mass in the electron channel. PNG
	Missing transverse energy in the muon channel. PNG
	Missing transverse energy in the electron channel. PNG
	Fit results of the muon-only fit. PNG
	Uncertainties of the muon-only fit. PNG
	Fit results of the electron-only fit. PNG
	Uncertainties of the electron-only fit. PNG
	Correlation matrix of the combined muon/electron fit. PNG
	Uncertainties of the combined muon/electron fit. PNG

Cross Check Analysis -- Muon Channel with muon-in-jet tagging	Abbreviated Caption
	Jet multiplicity in muon channel with at least one muon-in-jet. The measured cross section is 163 +/-21 (stat.) +/-35 (syst.) +/-7 (lumi.) pb PNG

Cross Check Analysis -- Neural Net	Abbreviated Caption
	Fit result of neural net cross-check analysis. The measured cross section is 151 +/-15 (stat.) +35-28 (syst.) +/-6 (lumi.) pb PNG

Cross Check Analysis -- Electron Channel	Abbreviated Caption
	B-tag multiplicity in the electron channel. The measured cross section is 169 +/-13 (stat.) +39-32 (syst.) +/-7 (lumi.) pb PNG

-- SalvatoreRoccoRappoccio - 14-Mar-2011