Construction of Covariant Bases for Two‐Particle Reactions

Abstract A method for the construction of the Lorentz‐covariant bases occurring in the decomposition of spinor amplitudes (M‐functions) of four massive particle processes is given. Each particle of spin‐ is described by a spinor state of the type‐(s, 0) and/or (0, s), but the essential parts of our method apply whatever the type of spinor state used, and the necessary relations between the hitherto familiar types of spinor states are given, by means of which the relationship between the resulting sets of invariant amplitudes can be made explicit. By way of illustration four worked examples are presented.