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

The normalized differential cross section of top-quark pair production in association with jets in the semileptonic ($e,\mu+$jets) top-quark pair decay channel has been investigated as a function of the nverse of the invariant mass of the $t\bar{t}+1-$jet system. This process is sensitive to the top-quark mass since gluon radiation depends on the mass of the quarks. The analysis is based on proton-proton collision data at a center-of-mass energy of 7 TeV collected by the ATLAS experiment at the LHC, and corresponding to an integrated luminosity of 4.6 $fb^{-1}$. The result is compared to a theoretical prediction at next-to-leading order accuracy in quantum chromodynamics, allowing to uniquely define the mass scheme. In this novel method the extracted top-quark pole mass is: \[ m^{pole}_{t}=173.7 \pm 1.5 ~({\rm stat.}) \pm 1.4 ~({\rm syst.})~ ^{+ 1.0}_{-0.5} ~({\rm theo.})~{\rm GeV}. \] The statistical uncertainty (stat.) is the largest error in this analysis. The experimental uncertainty (syst.) accounts for the imperfections in the modeling of the detector response, the background yield and the signal modeling. The theoretical error (theo.) includes the uncertainty due to missing higher orders in the perturbative NLO calculation in addition to those due to the parton distribution functions (PDFs) and the value of $\alpha_{s}$ used in the calculations.