Neutral-current results without gauge theories

Abstract

Low-energy weak interactions are phenomenologically described in terms of an intrinsic part possessing a global SU(2) symmetry plus an additional electromagnetic correction. This description reconstructs the Weinberg-Salam SU(2) ⊗ U(1) gauge-theory effective Lagrangian. Use of dispersion relations and Schwarz inequalities provides a lower bound on the range of the charged-current weak force, comparable to that obtained from gauge theories. The connection with the usual gauge-theory approach, especially the work of Georgi and Weinberg based on the group $\mathrm{SU}\mathrm{}\left(2\right)\mathrm{}\otimes \mathrm{U}\mathrm{}\left(1\right)\mathrm{}\otimes G$, is elucidated.