Precise measurement of the top-quark mass at the CMS experiment using the ideogram method

The mass of the top quark is measured using a sample of t anti t candidate events with one electron or muon and at least four jets in the final state, collected by CMS in proton-proton collisions at √(s)=8 TeV at the LHC. The candidate events are selected from data corresponding to an integrated luminosity of 19.7 fb^-1. For each event the top-quark mass is reconstructed from a kinematic fit of the decay products to a t anti t hypothesis. In order to minimize the uncertainties from jet energy corrections, the top-quark mass is determined simultaneously with a jet energy scale factor (JSF), constrained by the known mass of the W boson decaying to quark-antiquark pairs. A joint likelihood fit taking into account multiple interpretations per event - the ideogram method - is used. From the simultaneous fit, a top-quark mass of 172.15±0.19(stat.+JSF)±0.61(syst.) GeV is obtained. Using an additional constraint from the determination of the jet energy scale in γ/Z+jet events yields m_t=172.38±0.16(stat.+JSF)±0.49(syst.) GeV. The results are discussed in the context of different event generator implementations. Possible kinematic biases are studied by performing the measurement in different regions of the phase space.