We calculate the typical size of loop corrections to electroweak observables arising from nonstandard Zt¯t and Wtb vertices. We use an effective Lagrangian formalism based on the electroweak gauge gorup SU(2${)}_{\mathit{L}}$×U(1${)}_{\mathit{Y}}$→U(1${)}_{\mathrm{EM}}$. Limits on the nonstandard model top quark couplings from electroweak observables are presented and compared with previously obtained limits. © 1996 The American Physical Society.

• Received 23 June 1995

DOI:https://doi.org/10.1103/PhysRevD.53.1721