Structure effects of the two protons - two neutrons correlations

TL;DR

This paper investigates the effects of proton-neutron correlations in superfluid nuclei using a boson approximation, estimating interaction strength via symmetry energy and analyzing excitation states.

Contribution

It introduces a boson approximation approach to study proton-neutron correlations and explicitly derives the RPA vacuum for superfluid nuclei.

Findings

Estimated interaction strength from symmetry energy.

Explicit RPA vacuum derivation.

Discussion of electroexcitation to isovector monopole states.

Abstract

The proton-neutron 2 particles - 2 holes correlations in superfluid nuclei, described by an effective, Josephson-type interaction ~[(P+N-)+(P-N+)], are studied within a boson approximation. The strength of this interaction is estimated using the symmetry energy for an even-even system of nucleons lying on the same degenerate level. The RPA vacuum is obtained explicitly, and the electroexcitation to isovector monopole states of oscillatory pair exchange between the proton and neutron superfluids is briefly discussed.