  Focusing attention on top-quark pair production and its decay processes at
the LHC, non-standard top-quark couplings are studied based on the effective
Lagrangian constructed with SU(3)X SU(2)X U(1) invariant dimension-6 operators.
The optimal-observable analysis is carried out for the charged-lepton
distributions in pp -> t t-bar X -> l^+ X' (l=e or mu) in order to estimate the
expected statistical uncertainties in measurements of those non-standard t
t-bar g and tbW couplings that contribute to this process in the leading order.
