Renormalizable gauges and radiative corrections in gauge theories

Abstract

Radiative corrections in gauge theories are used to study physical processes on the basis of the standard electroweak model. The concepts of gauge invariance and gauge dependence are investigated by considering the electromagnetic couplings of neutrinos using a generalized nonlinear renoI1nalizable gauge. Firstly, the charged weal, vector boson field is found to satisfy the naive Ward identity and in consequence the one-loop contributions give zero neutrino charge. The separate diagrams contributing to the photon self-energy are transverse and the divergent parts gauge independent. Secondly, in Cl spontaneously broken theory the one-loop contributions to the background field vacuum polarization are separately transverse. Kallosh's theorem .• is also verified in this 'case. The results of a massless limit of the broken theory are, however not those of the unbroken theory. The electromagnetic form factor of the neutrino is finally considered and shown to be a complicated function of the gauge parameter. The charge radius computed from the form factor is gauge dependent , It is then concluded that the neutrino charge radius has no physical meaning in the standard model