Distinction between sequential and direct three-body decays

TL;DR

This paper analyzes the mechanisms of three-body decays in many-body resonances, distinguishing between sequential and direct decay modes, and discusses how momentum distributions reveal decay modes and resonance structures, exemplified by $^{9}$Be decay.

Contribution

It provides a detailed comparison of sequential and direct three-body decay mechanisms and discusses how momentum distributions can be used to infer decay modes and resonance structures.

Findings

Sequential decay involves two-body intermediate states.

Direct decay involves simultaneous emission of all three particles.

Momentum distributions encode information about decay modes.

Abstract

We discuss the three-body decay mechanisms of many-body resonances. Sequential decays proceed via two-body configurations after emission of the third particle. In direct decay all three particles leave simultaneously their interaction regions. The intermediate paths within the interaction regions are not observables and only accessible through models. The momentum distributions carry, apart from polarization, all possible information about decay modes and resonance structure. In this context we discuss detailed results for the decay of the $^{9}$Be($5/2^-$) resonance.