Dispersive effects for the nuclear paramagnetic susceptibility

Abstract

Dedicated to Professor Friedrich Beck on the occasion of his 60th birthday Dispersive effects coming from pionic degrees of freedom (virtual magnetic pion photoproduction) are shown to reproduce the nucleonic magnetic susceptibility and to yield a parallel quenching in nuclei. The relative importance of low lying nuclear vs. A-excitations is discussed and the difference of their role for the magnetic and electric polarizability is pointed out.