Dynamical test of constituent quark models with πN reactions -: art. no. 065203

A dynamical approach is developed to predict the pi N scattering amplitudes starting with the constituent quark models. The first step is to apply a variational method to solve the three-quark bound state problem. The resulting wave functions are used to calculate the N*-->pi N, pi N, pi Delta vertex functions by assuming that the pi and eta mesons couple directly to quarks. These vertex functions and the predicted baryon bare masses then define a Hamiltonian for pi N reactions. We apply a unitary transformation method to derive from the constructed Hamiltonian a multichannel and multiresonance reaction model for predicting: the pi N scattering amplitudes up to W = 2 GeV. With the parameters constrained by the Delta(1232) excitation; we have examined the extent to which the pi N scattering in the S-11 channel can be described by constituent quark models based on one-gluon-exchange or one-meson exchange mechanisms. It is found that the data seem to favor the spin-spin interaction due to one-meson exchange and the tensor interaction due to one-gluon exchange. A phenomenological quark-quark potential has been constructed to reproduce the S-11 amplitude.