Relativistic energy-dependent partial-wave analysis for particles with spin

Relativistic expansions of two-body scattering amplitudes are presented for reactions involving particles with arbitrary spins. The expansions are ''complete'' in that the entire dependence on the kinematical variables (energy, scattering angle, and azimuthal angle) is displayed explicitly in known functions. They are provided by the representation theory of the Lorentz group O(3,1) which in this case is identified as an ''internal Lorentz group,'' acting in a specific manner on two-particle states. The expansion coefficients, called Lorentz amplitudes, carry the dynamics of the reaction. The phenomenological motivation for writing such expansions is to be able to analyze large bodies of data simultaneously, e.g., the scattering data measured in a specific reaction for all angles and all available energies