Single top-quark t-channel production is exploited for studies of top quark properties. The analyses include the measurement of the CKM matrix element, $|V_{tb}|$, search for anomalous couplings of the top quark using a Bayesian neural network analys
is, measurement of single top-quark polarization which directly confirms the V-A nature of the $tWb$ production vertex, and the measurement of W-helicity fractions in the phase space sampled by a selection optimized for t-channel single top-quark production, orthogonal to the $toverline{t}$ final states used in traditional measurements of these properties. All measurements are found to be consistent with the standard model predictions.
Measurements involving top quarks provide important tests of QCD. A selected set of top quark measurements in CMS including the strong coupling constant, top quark pole mass, constraints on parton distribution functions, top quark pair differential c
ross sections, ttbar+0 and >0 jet events, top quark mass studied using various kinematic variables in different phase-space regions, and alternative top quark mass measurements is presented. The evolution of expected uncertainties in future LHC runs for the standard and alternative top quark mass measurements is also presented.
Top quark flavor changing neutral current (FCNC) interactions are highly suppressed in the Standard Model. Therefore, any large signal of FCNCs will indicate the existence of new interactions. In this paper, searches for FCNC interactions in top quar
k production and decay at the Tevatron and LHC are presented. FCNC searches in $trightarrow qZ$ and $trightarrow Hq$ decays, and in top quark production in $pprightarrow t+j$, $pprightarrow t+Z$ are summarized. Effect of top quark FCNCs on single top quark cross-section, and the searches for same-sign top quark pair production through FCNCs are also described. None of the searches yielded positive results and exclusion limits on branching rations, coupling strengths and cross-sections are obtained. Future prospects of FCNC searches are also briefly discussed.
Measurements of several top-quark properties, obtained from the CMS data collected in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV are presented. The results include measurements of the top pair charge asymmetry, the W helicity in top quar
k decays and the search for anomalous couplings, the top quark charge, and of the ttbar spin correlation. The fraction of top quarks decaying into a W-boson and a b-quark relative to all top quark decays, R=Br(t->Wb)/Br(t->Wq), as well as, the cross sections of ttbar events produced in association with a photon or a W or a Z boson are also presented.
