Three-cluster dynamics within an ab initio framework

TL;DR

This paper develops a fully antisymmetrized ab initio approach to three-cluster nuclear dynamics, applying it to helium-6 and comparing with experimental data and other computational methods.

Contribution

It introduces a novel formalism for three-cluster dynamics within the NCSM/RGM framework, enabling realistic, non-local interactions from fundamental nucleon-nucleon forces.

Findings

Successfully applied to $^6$He with good agreement to experiment

Provided insights into core polarization effects in helium-6

Demonstrated the method's consistency with other ab initio calculations

Abstract

We introduce a fully antisymmetrized treatment of three-cluster dynamics within the ab initio framework of the no-core shell model/resonating-group method (NCSM/RGM). Energy-independent non-local interactions among the three nuclear fragments are obtained from realistic nucleon-nucleon interactions and consistent ab initio many-body wave functions of the clusters. The three-cluster Schr\"odinger equation is solved with bound-state boundary conditions by means of the hyperspherical-harmonic method on a Lagrange mesh. We discuss the formalism in detail and give algebraic expressions for systems of two single nucleons plus a nucleus. Using a soft similarity-renormalization-group evolved chiral nucleon-nucleon potential, we apply the method to an $^4$He+$n+n$ description of $^6$He and compare the results to experiment and to a six-body diagonalization of the Hamiltonian performed within the harmonic-oscillator expansions of the NCSM. Differences between the two calculations provide a measure of core ($^4$He) polarization effects.