Low-energy theorems for strongly interactingW’s andZ’s

Abstract

Low-energy theorems are proved for the scattering of longitudinally polarized W and Z bosons that hold at a scale intermediate between $M_W$ and the characteristic mass scale of the symmetry-breaking sector. The theorems are proved without assuming a custodial SU(2) symmetry. Three methods are used: a perturbative power-counting analysis in the unitary gauge, a current-algebra derivation in renormalizable gauges, and a nonlinear chiral Lagrangian that is relevant in unitary or renormalizable gauges.