Measurement of the top quark mass in the $t\bar{t}$→ lepton+jets channel from $\sqrt{s}$=8 TeV ATLAS data

The top quark mass is measured using a template method in the $t\bar{t} \to$ lepton + jets channel (lepton = e, $\mu$) using ATLAS data recorded in the year 2012 at the LHC. The data were taken at a proton–proton centre-of-mass energy of $\sqrt{s}$=8 TeV and correspond to an integrated luminosity of 20.2 fb$^{−1}$ . The $t\bar{t} \to$ lepton + jets channel is characterised by the presence of a charged lepton, a neutrino and four jets, two of which originate from bottom quarks ($b$-jets). Exploiting a three-dimensional template technique, the top quark mass is determined together with a global jet energy scale factor and a relative $b$-to-light-jet energy scale factor. The mass of the top quark is measured to be $m_{\rm top}$ = 172.08 $\pm$ 0.39 (stat) $\pm$ 0.82 (syst) GeV, with a total uncertainty of 0.91 GeV. A combination with previous ATLAS $m_{\rm top}$ measurements is performed and results in $m_{\rm top}$ = 172.51 $\pm$ 0.27 (stat) $\pm$ 0.42 (syst) GeV, with a total uncertainty of 0.50 GeV.