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

A measurement is presented of the tt̅ inclusive production cross section in pp collisions at a center-of-mass energy of √s̅ = 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 tt̅ production cross section was measured to be 260 ± 1(stat) {-23}^{+22} (stat) ± 8(lumi) ± 4(beam) pb assuming a top-quark mass of 172.5 GeV, in good agreement with the theoretical prediction of 253{-15}^{+13} pb. The tt̅ → (e, μ) + jets production cross section in the fiducial region determined by the detector acceptance is also reported.