Gauge-Field Chiral Lagrangian

The SU(3)×SU(3) chiral Lagrangian with gauge fields is discussed, including a consideration of SU(3)-symmetry breaking. In addition to details of the formulation, applications to π-N scattering lengths, K⁺-N scattering lengths, and semileptonic decays are treated. The S-wave π-N scattering lengths are found to be independent of the vector-meson-dominance assumption. A possible "improvement" of the calculation by adding the N* particle is also discussed. The K⁺-N S-wave scattering lengths can be calculated in good agreement with experiment when all symmetry breaking (including ω-φ mixing) is put into the mass terms of the physical particles and it is assumed that the physical φ particle decouples from the nucleons. Alternative SU(3)-breaking schemes are investigated and, for a modified mass-term mixing model, the renormalizations to the Cabibbo theory for all semileptonic decays can be correlated in terms of one (known) parameter.