Asymptotic Conservation of Helicity for Vertex Functions Involving Arbitrary Spin

We examine the matrix element of a current with arbitrary number s of four vector indices between one particle states of definite helicity. The conservation of the angular momentum in the brick wall reference frame was used to derive a set of linear rela- tions between the matrix elements. Requiring the helicities of the particles to be conserved asymptotically, we derive a restriction on the spins of the particles. Specifically we show that the helicity cannot be conserved if the larger of the spins of the initial and the final particles are greater than s for massive particles. For the vector current, this means that the matrix element can conserve the helicity asymptotically only between the states of spin less than or equal to 1.