Measurement of Top Quark Properties in Single Top Quark Production at CMS

TL;DR

This paper reports on measurements of top quark properties in single top-quark production, including CKM matrix element, anomalous couplings, polarization, and W-helicity fractions, all consistent with the Standard Model.

Contribution

It presents new measurements of top quark properties in single top production using advanced analysis techniques, including Bayesian neural networks and phase space optimization.

Findings

Measured |Vtb| consistent with the Standard Model

No evidence of anomalous top couplings found

Confirmed the V-A structure of the top quark decay

Abstract

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 analysis, 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 $t\overline{t}$ final states used in traditional measurements of these properties. All measurements are found to be consistent with the standard model predictions.