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Search for anomalous Wtb couplings and avour-changing neutral currents in t-channel single top quark production in pp collisions at p s = 7 and 8 TeV
CMS Collaboration
CMS Collaboration
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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 s√=7 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 |f V R | < 0.16, |f T L | < 0.057, and − 0.049 < f T R < 0.048, respectively. For the FCNC couplings κ tug and κ tcg, the 95% CL upper limits on coupling strengths are |κ tug|/Λ < 4.1 × 10− 3 TeV−1 and |κ tcg|/Λ < 1.8 × 10− 2 TeV−1, where Λ is the scale for new physics, and correspond to upper limits on the branching fractions of 2.0 × 10−5 and 4.1 × 10−4 for the decays t → ug and t → cg, respectively.
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Date
2017-02
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Springer Verlag
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Keywords
Flavour Changing Neutral Currents, Hadron-Hadron scattering (experiments), Top physics
Citation
The CMS collaboration, Khachatryan, V., Sirunyan, A.M. et al. J. High Energ. Phys. (2017) 2017: 28. https://doi.org/10.1007/JHEP02(2017)028