Entanglement features in scattering mediated by heavy particles

The amount of information propagated by an intermediate heavy particle exhibits characteristic features in inelastic scatterings with $n\geq 3$ final particles. As the total energy increases, the entanglement entropy, between its decay products and other final particles, exhibits a universal sharp dip, suppressed by its small decay rate. This indicates an entanglement suppression from a low-energy effective theory to a channel dominated by an on-shell heavy particle. As demonstrations of these entanglement features, we study concrete models of $2\to 3$ and $2\to 4$ scatterings, which shed light on the entanglement structure beyond the area law derived for $2\to 2$ scattering. In practice, these features may be probed by suitably marginalizing the phase-space distribution of final particles.