EQUIVALENCE THEOREM AND ITS RADIATIVE-CORRECTION-FREE FORMULATION FORALL R(XI) GAUGES

The electroweak equivalence theorem quantitatively connects the physic al amplitudes of longitudinal massive gauge bosons to those of-the cor responding unphysical would-be Goldstone bosons. Its precise form depe nds on both the gauge-fixing condition and the renormalization scheme. Our previous modification-free schemes have applied to a broad class of R(xi) gauges including the 't Hooft-Feynman gauge but excluding the Landau gauge. In this paper we construct a new renormalization scheme ;in which the radiative modification factor C-mod(a) is equal to unity for all R(xi) gauges, including both 't Hooft-Feynman and Landau gaug es. This scheme makes C-mod(a) equal to unity by specifying a convenie nt subtraction condition for the would-be Goldstone boson wave functio n renormalization constant Z(phi)a. We build the new scheme for both t he standard model and the effective Lagrangian formulated electroweak theories (with either linearly or nonlinearly realized symmetry-breaki ng sector). Based upon these, a new prescription, called the ''divided equivalence theorem,'' is further proposed for extending the high ene rgy region applicable to the equivalence theorem.