Measurements of normalized differential cross sections for t ¯ t production in p p collisions at √ ( s ) = 7 TeV using the ATLAS detector

Abstract

Measurements of normalized differential cross-sections for top-quark pair production are presentedas a function of the top-quark transverse momentum, and of the mass, transverse momentum, and√rapidity of the t t ̄ system, in proton?proton collisions at a center-of-mass energy of s = 7 TeV . Thedataset corresponds to an integrated luminosity of 4.6 fb −1 , recorded in 2011 with the ATLAS detectorat the CERN Large Hadron Collider. Events are selected in the lepton+jets channel, requiring exactlyone lepton and at least four jets with at least one of the jets tagged as originating from a b -quark.The measured spectra are corrected for detector efficiency and resolution effects and are comparedto several Monte Carlo simulations and theory calculations. The results are in fair agreement withthe predictions in a wide kinematic range. Nevertheless, data distributions are softer than predictedfor higher values of the mass of the t t ̄ system and of the top-quark transverse momentum. Themeasurements can also discriminate among different sets of parton distribution functions.