The relation between the photonuclear E1 sum rule and the effective orbital g-factor

The connection between the enhancement factor (1 + kappa) of the photonuclear E1 sum rule and the orbital angular momentum g-factor (g(l)) of a bound nucleon is investigated in the framework of the Landau-Migdal theory for isospin asymmetric nuclear matter. Special emphasis is put on the role of gauge invariance to establish the kappa-g(l) relation. By identifying the physical processes which are taken into account in kappa and g(l), the validity and limitations of this relation will be discussed. The connections to the collective excitations and to nuclear Compton scattering are also shown. (C) 2004 Elsevier B.V. All rights reserved.