Hard meson corrections to the amplitude for radiative muon capture and the elementary particle method

Hard meson corrections to the amplitude of radiative muon capture on the proton are derived within the framework of vector meson dominance in the tree approximation. The weak form factors are mediated by π, ρ and A₁ mesons which may radiate. The model reproduces the terms in the amplitude of lower order in the momentum transfers as derived from low-energy theorems and determines higher-order terms which are otherwise ambiguous or undetermined. Arguments are given why a similar approach to radiative muon capture in nuclei in an elementary particle method is expected to fail.