Gauge Condition in Helicity Formalism
Takeshi Ebata, Tomoya Akiba, K. E. Lassila · Progress of Theoretical Physics · 1970
Through the example of boson Compton scattering, the gauge invariance requirement is formulated in the helicity formalism. The formalism assumes that the longitudinal helicity amplitudes vanish as powers of photon invariant “mass”, and the virtual Compton scattering can be treated in a unified way with the real one. The formalism is used to discuss the problem of Born terms, Regge pole theory and other related topics. Since the formalism exploit only the knowledge of crossing matrix, it should be applicable to more complicated reactions.