Measurement of the top pair production cross-section in 8 TeV proton-proton collisions using kinematic information in the lepton+jets final state with ATLAS

TL;DR

This paper reports a measurement of the top-antitop quark pair production cross-section at 8 TeV using ATLAS data, employing kinematic analysis and b-jet identification to improve accuracy, and finds results consistent with theoretical predictions.

Contribution

First measurement of the $tar{t}$ cross-section at 8 TeV in the lepton+jets channel using a likelihood fit and b-jet tagging with ATLAS data.

Findings

Measured cross-section: 260 ± 1 (stat) +22/-23 (syst) ± 8 (lumi) ± 4 (beam) pb.

Results agree with the theoretical prediction of approximately 253 pb.

Analysis techniques improve signal-to-background discrimination.

Abstract

A measurement is presented of the $t\bar{t}$ inclusive production cross-section in $pp$ collisions at a center-of-mass energy of $\sqrt{s}=8$ TeV using data collected by the ATLAS detector at the CERN Large Hadron Collider. The measurement was performed in the lepton+jets final state using a data set corresponding to an integrated luminosity of 20.3 fb$^{-1}$. The cross-section was obtained using a likelihood discriminant fit and $b$-jet identification was used to improve the signal-to-background ratio. The inclusive $t\bar{t}$ production cross-section was measured to be $260\pm 1{\textrm{(stat.)}} ^{+22}_{-23} {\textrm{(syst.)}}\pm 8{\textrm{(lumi.)}}\pm 4{\mathrm{(beam)}}$ pb assuming a top-quark mass of 172.5 GeV, in good agreement with the theoretical prediction of $253^{+13}_{-15}$ pb. The $t\bar{t}\to (e,\mu)+{\mathrm{jets}}$ production cross-section in the fiducial region determined by the detector acceptance is also reported.