Towards a Simultaneous Measurement of the Top Quark Mass and Decay Width with Single Top Quark Events at CMS

We report a precise measurement of the mass of the top quark in the \( {t}\) -channel, which is the most dominant production process for single top quarks at the LHC. The final state comprises a top quark along with a light quark, giving rise to at least two jets, of which one arises from the hadronization of a b-quark, an isolated high-momentum lepton (electron or muon), and a large missing transverse momentum due to an escaping neutrino from the W boson decay. The study uses proton-proton collision data recorded by the CMS experiment during 2016 at \(\sqrt{s}=13\) TeV. Dominant standard model backgrounds are studied in complementary regions defined based on the number of b- and light-quark jets in the final state. A multivariate technique that relies on boosted decision tree and deep neural networks is deployed to separate signal from backgrounds. The top-quark mass is reconstructed using kinematic information from the W boson and the b jet. We obtain the top quark mass from a fit and investigating further to study a simultaneous measurement of mass and width.