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We calculate the rates of the 16 O (0 + ⇄0 − ) 16 N axial transitions in the model of a relativistic nucleon bound in scalar and vector potentials. Compared with the usual Schrodinger description, we find an appreciable increase of these transition rates and, as a result, their use as test cases of exchange currents may be questionable.

We calculate the local space-like component of the relativistic nucleon-nucleus potential from nuclear matter results via a local density approximation. This component seems too small to remove the discrepancy between calculated and measured magnetic moments of nuclei.

We study the effect of the expansion on the cluster production rates inside the fireball, which is assumed to be formed during a high energy nucleus-nucleus collision. It is shown that the chemical abundances may be far from their equilibrium values, if the expansion is as fast as predicted by the intranuclear cascade calculations.

We show that the Nambu-Jona-Lasinio model can distinguish observables, such as the meson masses, the pion decay constant and the constituent quark mass, which have logarithmic divergences, from quadratically divergent quantities such as the quark condensate 〈yψ〉 or the current quark mass. The latter can be eliminated from the lagrangian which can then be regularized with a single subtraction involving a cut-off mass. The range of possible cut-offs is considerably enlarged when it is realized that the quadratically divergent current quark mass requires two subtractions and therefore two cut-off parameters.

We investigate in the case of nuclear matter the energy dependence of the various single-nucleon potentials which have recently been defined in the framework of a relativistic quantum field approach. We exhibit which one among these potentials can be associated with the central part of the shell-model or of the optical-model potential in finite nuclei.

The pion structure function is investigated in a simple model, where pion and constituent quark fields are coupled through the simplest pseudoscalar coupling. The imaginary part of the forward gamma* pi-> gamma* pi scattering amplitude is evaluated and related to the structure functions. It is shown that the introduction of non-perturbative effects, linked to the size of the pion and preserving gauge invariance, allows a connection with the quark distribution. It is predicted that higher-twist terms become negligible for Q2 larger than about 2 GeV2 and that quarks in the pion have a momentum fraction smaller than in the proton case., 14 pages, 6 figures, LaTeX, elsart class