The Equivalence theorem and its radiative correction - free formulation for all R(xi) gauges

The electroweak equivalence theorem quantitatively connects the physical amplitudes of longitudinal massive gauge bosons to those of the corresponding {ital unphysical} would-be Goldstone bosons. Its precise form depends on both the gauge-fixing condition and the renormalization scheme. Our previous modification-free schemes have applied to a broad class of R{sub {xi}} gauges including the `t Hooft{endash}Feynman gauge but excluding the Landau gauge. In this paper we construct a new renormalization scheme in which the radiative modification factor C{sub mod}{sup a} is equal to unity for all R{sub {xi}} gauges, including both `t Hooft{endash}Feynman and Landau gauges. This scheme makes C{sub mod}{sup a} equal to unity by specifying a convenient subtraction condition for the would-be Goldstone boson wave function renormalization constant Z{sub {phi}{sup a}}. We build the new scheme for both the standard model and the effective Lagrangian formulated electroweak theories (with either linearly or nonlinearly realized symmetry-breaking sector). Based upon these, a new prescription, called the {open_quotes}divided equivalence theorem,{close_quotes} is further proposed for extending the high energy region applicable to the equivalence theorem. {copyright} {ital 1997} {ital The American Physical Society}