Optimal-observable analysis of possible non-standard top-quark couplings in pp→tt¯X→ℓ+X′

Possible non-standard top-quark interactions with the gluon and the W boson induced by SU(3)×SU(2)×U(1) gauge-invariant dimension-6 effective operators are studied for hadron-collider experiments. Current limits on top-gluon couplings are presented by using the latest experimental data of tt¯ productions at the Tevatron and the Large Hadron Collider (LHC). The optimal-observable procedure is applied to the charged-lepton distributions in pp→tt¯X→ℓ+X′ (ℓ=e or μ) at the LHC in order to estimate the expected statistical uncertainties in measurements of those non-standard top-gluon and top-W couplings that contribute to this process in the leading order.