Kinematic Singularities of the Ball-Chew-Pignotti Multiparticle Amplitudes

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Abstract
For multiparticle reactions involving massive particles of any spin, the amplitudes introduced by Bali, Chew, and Pignotti (BCP) are considered as functions of the scalar products between four-momenta. A method previously used by Trueman for 2-to-2 particle reactions and by this author for multiparticle helicity amplitudes is used to classify and explicitly extract the kinematic singularities of the BCP amplitudes. This method concentrates on the Lorentz-group parameters that define the state vectors in terms of which the amplitudes are constructed. The basic assumption is that the kinematic singularities of the amplitudes are due solely to the singular behavior of these group parameters on certain surfaces, given by the vanishing of particular Gram determinants, in the space of the invariant variables. The kinematic singularities take a form which seems suitable for analyzing kinematic constraints in a factorizable multiperipheral model.