It is shown that within the framework of a non-relativistic quark model with string-like confinement and an instanton induced residual quark-quark interaction it is possible to account simultaneously for the baryon and the meson spectra, including the 7r-q-t/' splitting for pseudoscalar mesons, up to energies of roughly 2 GeV.

Dedicated to Professor Theo Mayer-Kuckuk on the occasion of his 60th birthdayWithin the framework of the non-relativistic quark model (NRQM) we discuss the influence of the coupling between baryonic excitations and meson fields. This leads to the interpretation of the baryon resonances as bound (q)3-configurations embedded in the corresponding meson-baryon continua. This concept is formulated analytically and applied to the description of the low-lying (N = 0)-and (N = 1)-multiplets with strangeness (S=0) and (S=-1). It turns out that the effects of this coupling are comparable in size to the effects induced by the hypcrfine interaction. In particular, a remarkable cancellation of the spin-orbit forces of the qq-interaction and the meson-baryon interaction is observed. The implications of the strong baryon-meson coupling on the baryon-baryon interaction and on the formulation of the Hamiltonian for a multibaryon system are briefly discussed.

Within the framework of the constituent quark model we discuss the effects of different types of meson-baryonbaryon vertex operators on the form factors and the coupling strengths of the lowest-lying positive and negative parity non-strange baryons. We compare the quark pair creation model (3po-model) with the SU(6)-model in which mesons are treated as elementary fields that directly couple to the quarks. The latter model is employed both in the so-called static limit and in a modification motivated by Galilei invariance. It is demonstrated that the inclusion of non-static effects simulates some features of the 3Po vertex. Especially the reaction nN~nnN is found to be very sensitive to the different assumptions on the dynamics of the q~ pair creation process. More indirect hints for the internal structure of the mesons might be obtained from the predicted asymmetry for the two form factors of N ~ A + 7~ and A ~ N + n, which occurs in the 3po-model, only.

It is pointed out that the existence of similar collective band structure fostered on the excited J = 112 states is a systematic feature of the nonstrange and strange baryon resonances.The purpose of this note is to point out that the available data concerning the baryon resonances in the X, A, A and sector suggest strongly the existence of collective bands based on the first-excited J" = 1/2* states. Further, collective bands in these baryons are found to be similar-they are characterized by a single, flavour-independent parameter governing the intraband excitations.The constituent-quark model (CQM) has enjoyed considerable phenomenological success vis-&vis a unified interpretation of baryon resonances in the past [l-141. However, despite its impressive overall efficacy, the model has not been able to provide satisfactory description as pure states of some specific resonances such as the Roper resonance as well as its counterparts in the A, A and E spectra. This apparent failure of the CQM prompted alternative descriptions of these resonances in terms of the collective degrees of freedom characterizing the underlying system. In the MIT bag model the Roper resonancewas sought to be described as a breathing mode of the bag [15]. Although the bad description highlighted the inherently collective nature of these resonances, it is not easily amenable to extension to cover higher excitations.An attempt was also made to rationalize the anomalous occurrence of the first-excited J" = 1/2+ states by invoking spatially deformed mean fields [16-201 which where postulated to exist in addition to the interquark interactions operating in the (q)s configuration. The occurrence of collective bands discussed here-and these seem to coexist with the states arising from the usual configurations-may be viewed as an essential implication of the existence of the mean fields embodying collective features through which one earlier