SMatrix for Yang-Mills and Gravitational Fields

Abstract
A method is suggested (and applied to the Yang-Mills and gravitational fields) for the construction of the generating functional (S matrix) for fields possessing an invariance group. The unitarity and gauge independence of the S matrix on the mass shell are seen explicitly. DOI: http://dx.doi.org/10.1103/PhysRevD.2.2841 © 1970 The American Physical Society