Six-fermion weak interactions, in addition to the usual four-fermion weak interactions, may exist. Limits on the strength of such interactions deduced from low-energy decay phenomena are not sufficient to exclude observable effects of six-fermion couplings at high energies. In particular, the process $\nu +p\to \nu +\mu +\overline{e}+p$ may be attributed either to six-fermion couplings, or to the existence of intermediary vector bosons.

• Received 5 August 1963

DOI:https://doi.org/10.1103/PhysRev.133.B130