A quartet BCS-like theory

TL;DR

This paper develops a BCS-like theoretical framework for quartet correlations in nuclear systems, showing good agreement with exact results and highlighting the absence of a sharp phase transition.

Contribution

It introduces a novel BCS-like theory for quartet correlations that differs from traditional mean field approaches by having zero pair anomalous density.

Findings

Good agreement with exact results

No sharp quarteting phase transition

Shared qualitative features with pairing correlations

Abstract

We introduce a BCS-like theory for the quartet correlations induced by the isovector pairing interaction. It is based on a coherent state of BCS type and, unlike usual mean field approaches, it displays a vanishing pair anomalous density $\langle c^\dagger c^\dagger\rangle =0$. We find good agreement between our theory and the exact results. We discuss how the pairing and quarteting correlations share some similar qualitative features within the BCS approach. However, there is no sharp quarteting phase transition. We also present various ways in which our theory may be further developed.