A common problem in several subfields of physics is reconstructing the process by which a body—a molecule, nucleus, or high-energy particle—breaks apart into three or more fragments. Even when all fragments are detected and their velocities measured, it’s not always easy. Across fields, researchers distill and interpret the fragmentation’s essential features with a suite of powerful tools, including the Dalitz plot, a visualization of the kinetic energy carried by each fragment. But ambiguities can still remain.
Consider, for example, the breakup of triply ionized carbonyl sulfide, OCS3+, into O+, C+, and S+. Three fragmentation channels are possible: two that are sequential, in which either the O–C or the C–S bond breaks first, and one that is concerted, in which both bonds break at the same time. For each of the sequential channels, conservation of momentum during the first bond-fission step imposes a...
