Chiral perturbation theory for vector mesons.

The interactions of , K , and ! vector-mesons with low-momentum , K and pseudoscalar mesons are constrained by chiral symmetry. We derive a heavy vector-meson chiral Lagrangian in which the vector mesons are treated as heavy static matter elds. The unknown couplings of the chiral Lagrangian are further related using the 1=Nc expansion. Chiral perturbation theory is applied to the vector-meson mass matrix. At one-loop there are large corrections to the individual vector meson masses, but the singlet-octet mixing angle remains almost unchanged. The parity-violating s-wave ! weak decay amplitude is derived in the combined chiral and large Nc limits. Rare decays provide a sensitive test of non-leptonic neutral current structure.