Complex Angular Momentum and Infinite Helicity Sums

Abstract

Previous discussions of the continuation to complex angular momentum of three-particle unitarity integrals for simple diagrams are reformulated in terms of infinite helicity sums. This is achieved by a redefinition of the partial-wave projection of the production amplitudes. It is found that the helicity sums can be made to converge by suitable choice of complex contours for the phase-space integral. It is shown that this leads to the same results as found previously without the introduction of helicity sums.