Search for anomalous Wtb couplings and top FCNC in t-channel single-top-quark events

Collaboration
2014
20 pages
Report number:
  • CMS-PAS-TOP-14-007
Experiments:

Citations per year

201420152016201720188101
Abstract:
Single-top-quark events in the tt-channel are used to probe Wtb anomalous couplings and to search for top quark Flavor Changing Neutral Current (FCNC) interactions in proton-proton collisions at s=7\sqrt{s}=7 TeV. The analyzed data correspond to an integrated luminosity of 5~fb1^{-1}. Events with the top quark decaying into a muon, neutrino and b-quark are selected. A Bayesian neural network is used to discriminate between signal and backgrounds. The observed event yields are consistent with SM prediction, and exclusion limits at 95\% C.L. are determined. The exclusion limits on anomalous right vector and left tensor couplings of the Wtb vertex are found to be fVR<0.34|f_{V}^{R}|< 0.34 and fTL<0.09|f_{T}^{L}|<0.09. In the scenarios with FCNC tcg and tug couplings, limits on the coupling strengths are found to be κtug/Λ<1.8102 TeV1, κtcg/Λ<5.6102 TeV1\kappa_{tug}/\Lambda < 1.8 \cdot 10^{-2}~ \mathrm{TeV^{-1}},\ \kappa_{tcg}/\Lambda < 5.6 \cdot 10^{-2} ~ \mathrm{TeV^{-1}} which corresponds to limits on the branching ratios Br(t  u+g) < 3.55×104, Br(t  c+g) < 3.44×103Br(t~\rightarrow~u+g)~<~3.55\times10^{-4},\ Br(t~\rightarrow~c+g)~<~3.44\times10^{-3}.
Note:
  • Preliminary results
  • Data
  • neutral current: flavor changing
  • coupling: (top W bottom)
  • coupling: tensor
  • coupling: vector
  • neural network: Bayesian
  • p p: scattering
  • top: branching ratio: upper limit
  • background
  • muon: final state