Single top quark events produced in the t channel are used to set limits on anomalous Wtb couplings and to search for top quark flavour-changing neutral current (FCNC) interactions. The data taken with the CMS detector at the LHC in proton-proton collisions at √s = 7 and 8TeV correspond to integrated luminosities of 5.0 and 19.7 fb-1, respectively. The analysis is performed using events with one muon and two or three jets. A Bayesian neural network technique is used to discriminate between the signal and backgrounds, which are observed to be consistent with the standard model prediction. The 95% confidence level (CL) exclusion limits on anomalous right-handed vector, and left- and righthanded tensor Wtb couplings are measured to be |fRV| < 0.16, |fLT| < 0.057, and -0.049 < fRT < 0.048, respectively. For the FCNC couplings κtug and κtcg, the 95% CL upper limits on coupling strengths are |κtug|/Λ < 4.1 x 10-3 TeV-1 and |κtcg|/Λ < 1.8 x 10-2 TeV-1, where Λ is the scale for new physics, and correspond to upper limits on the branching fractions of 2.0 x 10-5 and 4.1 x 10-4 for the decays t → ug and t → cg, respectively.
- Flavour Changing Neutral Currents
- Hadron-Hadron scattering (experiments)
- Top physics