REACTIONS INVOLVING POLARIZED PARTICLES OF ZERO REST MASS

In this paper the group-theoretical point of view is used for the description of the spin states of particles of zero rest mass. Complete sets of operators and of their eigenfunctions for a system of two particles are found in the representation of the momenta and spins. The statistical tensors for the particles produced in a reaction of the type a + b → c + d or a → c + d are obtained in the case in which one of these particles has no rest mass. The most general selection rules are derived for the reaction a + b → c + d in the form of relations between the statistical tensors, under the condition that the space and time parities are conserved. The wave functions are calculated for a system of two identical particles of zero rest mass.