Determination of the top-quark pole mass using $t \bar{t}+1$-jet events collected with the ATLAS experiment in 7 TeV $pp$ collisions

TL;DR

This paper presents a precise measurement of the top-quark pole mass using the differential cross section of top-quark pair plus one jet events at 7 TeV LHC data, employing next-to-leading-order QCD predictions.

Contribution

It introduces a novel method to determine the top-quark pole mass from the $t\bar{t}+1$-jet system's invariant mass distribution, achieving the most precise measurement to date.

Findings

Measured top-quark pole mass: 173.7 GeV with uncertainties.

Achieved the most precise top-quark pole mass measurement.

Validated the method with NLO QCD predictions.

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 $t \bar{t}+1$-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, $m_t^{\rm pole}$, is: $m_t^{\rm pole}$ =173.7 $\pm$ 1.5 (stat.) $\pm$ 1.4 (syst.) $^{+ 1.0}_{-0.5}$ (theory) GeV. This result represents the most precise measurement of the top-quark pole mass to date.