Isospin dynamics in nuclear structure

Abstract

Abstract. We discuss some special aspects of the nuclear many-body problem related to isospin transfer. The major quantity of interest is the in-medium propagator of a particlehole configuration of the proton-neutron character, which determines the nuclear response to isospin transferring external fields. One of the most studied excitation modes is the Gamow-Teller resonance (GTR), which can, therefore, be used as a sensitive test for the theoretical approaches. Its low-energy part, which is responsible for the beta decay halflives, is especially convenient for this. Models benchmarked against the GTR can be used to predict other, more exotic, excitations studied at nuclear rare isotope beam facilities and in astrophysics. As far as the precision is concerned, the major problem in such an analysis is to disentangle the effects related to the underlying interaction and those caused by the many-body correlations. Therefore, approaches (i) based on fundamental concepts for the nucleon-nucleon interaction which (ii) include complex many-body dynamics are the preferred ones. We discuss progress and obstacles on the way to such approaches.

Equation of Motion Method to strongly correlated Fermi systems and Extended RPA approaches

“…The Dyson-BSEs in the pp-and ph-channels are a convenient starting point to study the particle-vibration coupling effects, which play a very important role for nuclear and condensed-matter systems [105,106]. Let us consider the response function in the ph-channel, which is the quantity describing excitations caused by external perturbations without particle transfer.…”