Soft-core meson-baryon interactions. II. pi N and K+ N scattering

The pi N potential includes the t-channel exchanges of the scalar mesons sigma and f(0), vector meson rho, tensor mesons f(2) and f(2)('), and the Pomeron as well as the s- and u-channel exchanges of the nucleon N and the resonances Delta, Roper, and S-11. These baryonic resonances are not generated dynamically. We consider them, at least partially, as genuine three-quark states, and we treat them in the same way as the nucleon. The Roper and S-11 resonances were needed to find the proper behavior of the phase shifts at higher energies in the corresponding partial waves. The soft-core pi N model gives an excellent fit to the empirical pi N S- and P-wave phase shifts up to T-lab=600 MeV. Also, the scattering lengths have been reproduced well, and the soft-pion theorems for low-energy pi N scattering are satisfied. The soft-core model for the K+N interaction is an SUf(3) extension of the soft-core pi N model. The K+N potential includes the t-channel exchanges of the scalar mesons a(0),sigma, and f(0), vector mesons rho,omega, and phi, tensor mesons a(2),f(2), and f(2)('), and the Pomeron as well as u-channel exchanges of the hyperons Lambda,Sigma,Sigma(1385), and Lambda(1405). The fit to the empirical K+N S-, P-, and D-wave phase shifts up to T-lab=600 MeV is reasonable and certainly reflects the present state of the art. Since the various K+N phase shift analyses are also not very consistent, scattering observables are also compared with the soft-core K+N model. A good agreement for the total and differential cross sections as well as the polarizations is found