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, |Vtb|, 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 tt‾ final states used in traditional measurements of these properties. All measurements are found to be consistent with the standard model predictions.
Highlights
The top quark is the most massive particle known to date
All three production modes are sensitive to tWb-vertex and new physics
TW- or s-channel production is useful in W and charged Higgs searches and t-channel production can be used to look for flavor changing neutral currents (FCNCs)
Summary
The top quark is the most massive particle known to date. The top quark decays via the weak interaction and due to its high mass, it has a very short lifetime which is smaller than the hadronization time-scale, 1/ΛQCD. These measurements are sensitive to the tWb-vertex both in production and in decay. Using the fact that |Vtb| is much larger than |Vtd| and |Vts|, an anomalous coupling at the tWb-vertex can be parametrized by fVL and can be related to the measured (σt−ch.) and the theoretical (σtt−hecoh..) t-channel cross sections using the following equation. |V | tb Figure 3: Summary of |Vtb| measurements made by CMS
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