Shell-Model Analyses of Weak and Electromagnetic Data: The Interplay of Many-Body and Single-Nucleonic Features

Abstract

Our understanding of nuclear structure suggests that the values of electromagnetic and weak observables measured in nuclear physics experiments reflect an interplay between “universal” properties of neutrons and protons as they exist in finite nuclei and highly state-specific coherent features of the many-body wave functions which describe how these neutrons and protons are combined into individual nuclear eigenstates. Only for the “single-particle” and “single-hole” nuclei adjacent to doubly-magic nuclei can the many-body aspects of such observables be approximately factored out in a trivial fashion. For the great majority of nuclei, the implications of experimental data about the general features of nuclear structure can emerge only after the idiosyncrasies of the different many-body aspects of the measured matrix elements are understood and extracted. Since we do not have, a priori, quantitatively accurate theories for many-body nuclear structure, confidence in the factorisation of the many-body features of nuclear matrix elements from the single-nucleonic elements is obtained only by internally consistent analyses of extensive sets of data.