| In the context of Rigged Hilbert Space scattering theory, the projective representations of the extended Poincare group adjoined by charge conjugation are used to describe scattering, with an emphasis on unstable intermediate particles. The conventional representations are discussed and an interpretation of some of the unconventional representations is proposed. In particular, the conventional representations are inadequate in the Rigged Hilbert Space and one must use those that give a doubling of the space of states under operations that reverse the direction of time. The problems associated with previous attempts to introduce such operations in the Rigged Hilbert Space of scattering, which led to an unphysical doubling of spaces, are avoided. Finally, applications of this description of scattering are applied to several unstable particles and particle system. |
