No-interaction theorem without Hamiltonian and Lagrangian formalism: invariant momentum on null cones

In a previous paper (G.Yoneda, Proc.R.Soc.London, A445,(1994),221), we proved the no-interaction theorem for four particles with the assumption that the (linear and angular) momentum on space-like planes is invariant. In this paper, we assume that the momentum on null cones is invariant and prove that there is no interaction for four particles.