Structure and three-body decay of $^9$Be resonances

TL;DR

This paper uses the complex-rotated hyperspherical adiabatic method to analyze the decay properties of $^9$Be resonances into a neutron and two alpha particles, providing detailed decay structures and comparing with experimental data.

Contribution

It introduces a detailed three-body decay analysis of $^9$Be resonances using complex rotation, revealing decay pathways and distributions consistent with experiments.

Findings

Branching ratios for sequential decay match measurements.

Momentum distributions agree with experimental Dalitz plots.

Identifies angular momentum configurations of decay substructures.

Abstract

The complex-rotated hyperspherical adiabatic method is used to study the decay of low-lying $^9$Be resonances into one neutron and two $\alpha$-particles. We investigate the six resonances above the break-up threshold and below 6 MeV: $1/2^\pm$, $3/2^\pm$ and $5/2^\pm$. The short-distance properties of each resonance are studied, and the different angular momentum and parity configurations of the $^8$Be and $^5$He two-body substructures are determined. We compute the branching ratio for sequential decay via the $^8$Be ground state which qualitatively is consistent with measurements. We extract the momentum distributions after decay directly into the three-body continuum from the large-distance asymptotic structures. The kinematically complete results are presented as Dalitz plots as well as projections on given neutron and $\alpha$-energy. The distributions are discussed and in most cases found to agree with available experimental data.