Elementary Collective Effects in Systems Containing Small Fermion-Numbers

Abstract

Collective effects are a typical nuclear feature that refers to the behavior of a group of 𝑁 fermions (protons and neutrons) within the atomic nucleus. Our interest lies in light nuclei only. Thus, we consider here, using the Lipkin model, a small-𝑁 fermion system at low-temperature 𝑇 and discover -collective phenomena. Our fermion-model simplicity allows one to gain insight into collective fermion behavior. We focus attention, for 𝑁<20, on several quantifiers. These include standard ones related to thermal behavior, such as entropy, and quantifiers of another kind, like quantum purity.