ATLAS collaboration (2826 authors)Aguilar-Saavedra, Juan AntonioAmor Dos Santos, Susana PatriciaAnjos, NunoAraque, Juan PedroCantrill, RobertCarvalho, JoãoCastro, Nuno FilipeConde Muiño, PatriciaDa Cunha Sargedas De Sousa, Mario JoseFiolhais, MiguelGalhardo, BrunoGomes, AgostinhoGonçalo, RicardoJorge, PedroLopes, LourencoMachado Miguens, JoanaMaio, AméliaManeira, JoséOnofre, AntónioPalma, AlbertoPedro, RutePina, João AntonioPinto, BelmiroSantos, HelenaSaraiva, JoãoSilva, JoséTavares Delgado, AdemarVeloso, FilipeWolters, Helmut2019-02-042019-02-042015-07-17http://dx.doi.org/10.1140/epjc/s10052-015-3544-0http://hdl.handle.net/10400.26/26806The top quark mass was measured in the channels $t\bar{t} \to \mathrm{lepton+jets}$ and $t\bar{t} \to \mathrm{dilepton}$ (lepton=$e, \mu$) based on ATLAS data recorded in 2011. The data were taken at the LHC with a proton--proton centre-of-mass energy of $\sqrt{s}=7$ TeV and correspond to an integrated luminosity of 4.6fb$^{-1}$. The $t\bar{t} \to \mathrm{lepton+jets}$ analysis uses a three-dimensional template technique which determines the top quark mass together with a global jet energy scale factor (JSF), and a relative $b$-to-light-jet energy scale factor (bJSF), where the terms $b$-jets and light-jets refer to jets originating from $b$-quarks and $u, d, c, s$-quarks or gluons, respectively. The analysis of the $t\bar{t} \to \mathrm{dilepton}$ channel exploits a one-dimensional template method using the $m_{\ell b}$ observable, defined as the average invariant mass of the two lepton+$b$-jet pairs in each event. The top quark mass is measured to be $172.33\pm 0.75(\rm {stat}) \pm 1.02(\rm {syst})$ GeV, and $173.79 \pm 0.54({\rm stat}) \pm 1.30({\rm syst})$ GeV in the $t\bar{t} \to lepton+jets$ and $t\bar{t} \to dilepton$ channels, respectively. The combination of the two results yields $m_{\mathrm top} = 172.99 \pm 0.48({\rm stat}) \pm 0.78({\rm syst})$ GeV, with a total uncertainty of $0.91$ GeV.engjournal article2019-02-04