Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China
Calculations of helicity amplitudes for the low-lying nucleon resonances are displayed based on a non-relativistic constituent quark model with a harmonic oscillator confinement. The explicit effect of quark confinement is shown. Our results show that the effect plays sizable role on some transition amplitudes of S-11(1535) and D-13(1520) resonances. The effect on the A(1232) transition amplitudes is less than 10%. However, the effect on the Roper resonance is remarkable but is inconclusive.