Ghent University Academic Bibliography


Search for anomalous Wtb couplings and flavour-changing neutral currents in t-channel single top quark production in pp collisions at root s=7 and 8 TeV

V. Khachatryan, A. M. Sirunyan, A. Tumasyan, W. Adam, E. Asilar, T. Bergauer, J. Brandstetter, E. Brondolin, M. Dragicevic, J. Eroe, et al. (2017) JOURNAL OF HIGH ENERGY PHYSICS.
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 and 8 TeV 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 right-handed tensor Wtb couplings are measured to be vertical bar f (V) (R) vertical bar < 0.16,aEuro,vertical bar f (T) (L) vertical bar < 0.057, and - 0.049 < f (T) (R) < 0.048, respectively. For the FCNC couplings kappa (tug) and kappa (tcg), the 95% CL upper limits on coupling strengths are vertical bar kappa (tug)vertical bar/I > < 4.1 x 10(- 3) TeV-1 and vertical bar kappa (tcg)vertical bar/Lambda < 1.8 x 10(- 2) TeV-1, where I > 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.
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