"Isochronic" dynamical systems and nullification of amplitudes
arXiv:hep-th/0305111 · doi:10.1016/S0370-2693(03)00838-4
Abstract
We construct the set of theories which share the property that the tree-level amplitudes nullify even if both initial and final states contain the same type of particles. The origin of this phenomenon lies in the fact that the reduced classical dynamics describes isochronic systems.
12 pages, 3 figures