Anomalous t-c-g coupling: The connection between single top production   and top decay
  Continuing earlier work, we examine the constraint on an anomalous t-c-g coupling from top quark decay. We find that from current CDF measurements of the branching ratio $t \rightarrow W b$, the minimum scale at which new physics can strongly modify the t-c-g coupling is \Ltcg $\geq$ about 950 GeV. At the upgraded Tevatron, single top production can constrain \Ltcg $\geq$ 4.5 TeV. The connection between t-c production and the decay $t \rightarrow c g$ is examined, showing how constraints on one lead to a constraint on the other. 
Tim Tait and C.--P. Yuan