Determination of the top-quark pole mass using tt¯ + 1-jet events collected with the ATLAS experiment in 7 TeV pp collisions

Abstract

The normalized differential cross section for top-quark pair production in association with at least one jet is studied as a function of the inverse of the invariant mass of the tt¯+1-jet system. This distribution can be used for a precise determination of the top-quark mass since gluon radiation depends on the mass of the quarks. The experimental analysis is based on proton– proton collision data collected by the ATLAS detector at the LHC with a centre-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.6 fb−1 . The selected events were identified using the lepton+jets top-quark-pair decay channel, where lepton refers to either an electron or a muon. The observed distribution is compared to a theoretical prediction at next-to-leading-order accuracy in quantum chromodynamics using the pole-mass scheme. With this method, the measured value of the top-quark pole mass, m pole t , is: m pole t = 173.7 ± 1.5 (stat.) ± 1.4 (syst.) +1.0 −0.5 (theory) GeV. This result represents the most precise measurement of the top-quark pole mass to date