R-matrix and dynamical model calculations of three-body resonance decay widths

Calculations of the decay widths of three-body resonances are considered using both R-matrix and dynamical three-body theoretical models. The R-matrix approach, which treats the three-body decay as two, ordered two-body decays, has both simultaneous and sequential particle emission pathways, each with an associated decay width. The question of how these two widths should be combined to determine the total resonance width is considered using comparisons with the width deduced from fully dynamical three-body model calculations. We use the decay of the well-understood {sup 6}He(2{sup +}, 1.8 MeV) resonance (into {sup 4}He+n+n) as a benchmark case.