Article,
Search for anomalous Wtb couplings and flavour-changing neutral currents in t-channel single top quark production in pp collisions at sqrt(s) = 7 and 8 TeV
(2016)cite arxiv:1610.03545Comment: Submitted to J. High Energy Phys. All figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-14-007/index.html.
Abstract
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 sqrt(s) = 7 and 8 TeV correspond to integrated
luminosities of 5.0 and 19.7 inverse-femtobarns, respectively. The analysis is
performed using events with one muon and two or three jets. A Bayesian neural
network technique, used to discriminate between the signal and backgrounds, is
found 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 |fV^R| < 0.16, |fT^L|
< 0.057, and -0.049 < fT^R < 0.048, respectively. For the FCNC couplings
kappatug and kappatcg, the 95% CL upper limits on coupling strengths are
|kappatug|/Lambda < 4.1E-3 TeV-1 and |kappatcg|/Lambda < 1.8E-2 TeV-1,
where Lambda is the scale for new physics, and correspond to upper limits on
the branching fractions of 2.0E-5 and 4.1E-4 for the decays t to ug and t to
cg, respectively.
