A class of renormalizable field theories of the weak interactions is investigated. These theories, of the type first suggested by Kummer and Segrè, postulate that the weak interactions are mediated by the simultaneous exchange of two scalar particles. It is found that although the leptonic and semileptonic weak interactions can be fairly easily described by a two-scalar-exchange mechanism, the structure of observed nonleptonic weak processes presents serious obstacles to the success of such a theory. Nevertheless, two particular models are discussed which may correctly describe not only the leptonic and semileptonic weak interactions but also nonleptonic weak processes.

• Received 13 June 1968

DOI:https://doi.org/10.1103/PhysRev.176.2086