E1+/M1+ AND S1+/M1+ AND THEIR Q2 DEPENDENCE IN GAMMA-NU N-]DELTA WITH RELATIVIZED QUARK-MODEL WAVE-FUNCTIONS

We calculate the multipole ratios E1+M1+ (electric quadrupole to magnetic dipole) and S1+M1+ (scalar quadrupole to magnetic dipole) for the reaction vN. We use the nonrelativistic transition operators but wave functions expanded in a large harmonic-oscillator basis which are the solutions of a "relativized" Hamiltonian (relativized wave functions), in order to test the dependence of the results on truncation of the wave-function basis. Our results show an M1+ multipole closer to the experimental data at the photon point, E1+(0)M1+(0)-0.2, and smaller values of these ratios than previous calculations at all Q2. The current-conservation condition between S1+ and L1+ (the longitudinal quadrupole multipole) is also satisfied to a better approximation with the relativized wave functions at values of Q2 where the model is believable. © 1990 The American Physical Society.