A reasonable low-energy chiral Lagrangian of vectors and pseudoscalars involves three a priori unknown coefficients for terms proportional to the Levi-Civita symbol ${\epsilon }_{\mu \nu \alpha \beta }$. We argue that these cannot, from a theoretical standpoint, be reliably determined by consideration of electromagnetic processes. Hence we use purely strong-interaction processes which enable us to determine two out of three of these. We examine the nucleon as a soliton excitation in the model and find that adjustment of the third parameter does not greatly change the, in most respects accurate, description of the nucleon obtained in a previous treatment by Meissner, Kaiser, and Weise. The paper includes a new and careful formulation of the addition of electromagnetism to the full Lagrangian.

• Received 13 November 1987

DOI:https://doi.org/10.1103/PhysRevD.37.3252