Reduction of Some Representations of the Generalized Bondi-Metzner Group

Abstract

The infinitesimal operators of a class of representations of the GBM group described in a previous paper are given in explicit form. All unitary representations of this type with positive ``rest mass'' are shown to be completely reducible; each irreducible component is characterized by the eigenvalue m2 of the rest-mass operator, by the lowest eigenvalue s(s + 1) of the ``spin'' operator and by the sign of an eigenvalue of a suitably defined operator Rs=.