Interpolating fields for spin-1 mesons

Three commonly used types of effective theories for vector mesons are shown to correspond to different choices of interpolating field for spin-1 particles and the rules for transforming between them are described. The choice of fields that transform homogeneously under the nonlinear realisation of chiral symmetry imposes no preconceptions about the types of coupling for the mesons, and so this representation is particularly useful for comparing different theories. By converting them into this form, hidden-gauge theories are shown to contain an adjustable parameter, the gauge coupling. The normal choice for this is seen to be one that reduces the momentum dependence of the effective $\rho\pi\pi$ coupling, explaining the success of the ``low-energy theorem" of that approach.