Forests, Groves and Higgs Bosons: Gauge Invariance Classes in Spontaneously Broken Gauge Theories

Abstract

We determine the gauge invariance classes of tree level Feynman diagrams in spontaneously broken gauge theories, providing a proof for the formalism of gauge and flavor flips. We find new gauge invariance classes in theories with a nonlinearly realized scalar sector. In unitarity gauge, the same gauge invariance classes correspond to a decomposition of the scattering amplitude into pieces that satisfy the relevant Ward Identities individually. In theories with a linear realized scalar sector in R_\xi gauge, no additional nontrivial gauge invariance classes exist compared to the unbroken case.

Comments: LaTeX2e, 16 pages, 215 feynmp figures and style included, published version