Variational and parquet-diagram calculations for neutron matter. I. Structure and Energetics

TL;DR

This paper introduces a combined variational and parquet-diagram method to analyze neutron matter with complex interactions, improving the calculation of effective interactions crucial for dynamic property predictions.

Contribution

It develops a novel approach merging variational and parquet-diagram theories to handle state-dependent nuclear interactions without complex symmetrization procedures.

Findings

Equation of state is reliably estimated even with simple models.

Effective interactions are highly sensitive to many-body treatment quality.

Method applied to neutron matter with Reid and Argonne v6 potentials.

Abstract

We develop the variational/parquet diagram approach to the structure of nuclear systems with strongly state-dependent interactions. For that purpose, we combine ideas of the general Jastrow-Feenberg variational method and the local parquet-diagram theory for bosons with state-dependent interactions (R. A. Smith and A. D. Jackson, Nucl. Phys. {\bf 476}, 448 (1988)). The most tedious aspect of variational approaches, namely the symmetrization of an operator dependent variational wave function, is thereby avoided. We carry out calculations for neutron matter interacting via the Reid and Argonne $v_6$ models of the nucleon-nucleon interaction. While the equation of state is a rather robust quantity that comes out reasonably well even in very simplistic approaches, we show that effective interactions, which are the essential input for calculating dynamic properties, depend sensitively on the quality of the treatment of the many-body problem.