Accurate partial resonance widths for collinear reactive collisions

We present three methods for obtaining resonance energies and total and partial widths from scattering matrix elements as a function of energy in the vicinity of an isolated resonance. The methods are applied to 14 resonances in collinear reactive scattering systems, and they yield stable and reasonably consistent results. In 12 of the cases the partial widths sum to significantly less (23%-76%) than the total width even though the eigenphase sum fits the generalized Breit-Wigner form very well. The quantal partial widths are used to compute branching ratios for comparison to approximate results.