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

CMS Physics Analysis Summaries
Report number	CMS-PAS-TOP-14-007
Title	Search for anomalous Wtb couplings and top FCNC in t-channel single-top-quark events
Corporate author(s)	CMS Collaboration
Collaboration	CMS Collaboration
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; CMS
Abstract	Single-top-quark events in the $t$-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 $\sqrt{s}=7$ TeV. The analyzed data correspond to an integrated luminosity of 5~fb$^{-1}$. 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 $\|f_{V}^{R}\|< 0.34$ and $\|f_{T}^{L}\|<0.09$. In the scenarios with FCNC tcg and tug couplings, limits on the coupling strengths are found to be $\kappa_{tug}/\Lambda < 1.8 \cdot 10^{-2}~ \mathrm{TeV^{-1}},\ \kappa_{tcg}/\Lambda < 5.6 \cdot 10^{-2} ~ \mathrm{TeV^{-1}}$ which corresponds to limits on the branching ratios $Br(t~\rightarrow~u+g)~<~3.55\times10^{-4},\ Br(t~\rightarrow~c+g)~<~3.44\times10^{-3}$.
Other source	Inspire
Related	superseded by: CERN-EP-2016-207
Email contact: [email protected] Fulltext in PDF Figure_001-a Figure_001-b Figure_002-a Figure_002-b Figure_003-a Figure_003-b Figure_003-c Figure_003-d Figure_003-e Figure_004 Figure_005 Figure_006 Figure_007 Figure_008 Figure_009 Figure_010-a Figure_010-b Figure_011 Additional information for the analysis (restricted access)