A 3-BODY FORCE MODEL FOR THE ELECTROMAGNETIC-EXCITATION OF THE NUCLEON

We have performed a calculation of the helicity amplitudes for the ele ctromagnetic excitation of nucleon resonances based on a three-body fo rce model for baryon structure. All parameters have been previously fi xed studying the baryon spectrum and therefore this is a parameter fre e calculation. We have taken into account the hyperfine mixing in all the baryon states and we present our results in comparison with those given by other approaches proposed in the literature. A brief discussi on on open problems is also given.