We analyze the constraint structure of the interaction of vector mesons with baryons using the classical Dirac constraint analysis. We show that the standard interaction in terms of two independent SU(3) structures is consistent at the classical level. We then require the self-consistency condition of the interacting system in terms of perturbative renormalizability to obtain relations for the renormalized coupling constants at the one-loop level. As a result we find a universal interaction with one coupling constant which is the same as in the massive Yang-Mills Lagrangian of the vector-meson sector.

We analyze the low-Q 2 behavior of the axial form factor G A (Q 2 ), the induced pseudoscalar form factor G P (Q 2 ), and the axial nucleon-to-delta transition form factors C A 5 (Q 2 ) and C A 6 (Q 2 ). Building on the results of chiral perturbation theory, we first discuss G A (Q 2 ) in a chiral effective-Lagrangian model including the a 1 meson and determine the relevant coupling parameters from a fit to experimental data. With this information, the form factor G P (Q 2 ) can be predicted. For the determination of the transition form factor C A 5 (Q 2 ), we make use of an SU(6) spin-flavor quarkmodel relation to fix two coupling constants such that only one free parameter is left. Finally, the transition form factor C A 6 (Q 2 ) can be predicted in terms of G P (Q 2 ), the mean-square axial radius r 2 A , and the mean-square axial nucleon-to-delta transition radius r 2 AN ∆ .

Using baryon chiral perturbation theory including vector mesons, we analyse various continuum contributions to the isoscalar electromagnetic spectral functions of the nucleon induced by the leading order couplings.