Feynman, R.P.; Gell-Mann, M.; Theory of the Fermi Interaction
Phys. Rev. 109 (1958) 193;

Reprinted in The Physical Review - the First Hundred Years, AIP Press (1995) CD-ROM.
The Development of Weak Interaction Theory, editor P. K. Kabir, Gordon and Breach Science Publishers, New York - London, (1963) 129.

Abstracts
The representation of Fermi particles by two-component Pauli spinors satisfying a second order differential equation and the suggestion that in decay these spinors act without gradient couplings leads to an essentially unique weak four-fermion coupling. It is equivalent to equal amounts of vector and axial vector coupling with two-component neutrinos and conservation of leptons. (The relative sign is not determined theoretically.) It is taken to be "universal'';
the lifetime of the agrees to within the experimental errors of 2%. The vector part of the coupling is, by analogy with electric charge, assumed to be not renormalized by virtual mesons. This requires, for example, that pions are also "charged'' in the sense that there is a direct interaction in which, say, a ^{o} goes to ^{–} and an electron goes to a neutrino. The
weak decays of strange particles will result qualitatively if the universality is extended to include a coupling involving a or fermion. Parity is then not conserved even for those decays like K 2 or 3 which involve no neutrinos. The theory is at variance with the measured angular correlation of electron
and neutrino in He^{6}, and with the fact that fewer than 10^{-4} pion decay into electron and neutrino.

Related references See also A. Salam, Nuovo Cim. 5 (1957) 299;
L. D. Landau, Nucl. Phys. 3 (1957) 127;
T. D. Lee and C. N. Yang, Phys. Rev. 105 (1957) 1671;
R. P. Feynman, Rev. of Mod. Phys. 20 (1948) 367;
W. B. Herrmansfeldt, D. R. Maxson, P. Stahelin, and J. S. Allen, Phys. Rev. 107 (1957) 641;
R. P. Feynman, Proc. of the Seventh Ann. Rochester Conf. on High Energy Nuclear Physics, Interscience Publishers, Inc., New York (1957);
B. M. Rustad and S. L. Ruby, Phys. Rev. 97 (1955) 991;
M. T. Burgy, Epstein, Krohn et al., Phys. Rev. 107 (1957) 1731;
R. E. Behrends and C. Fronsdal, Phys. Rev. 106 (1957) 345;
D. A. Bromley, Almqvist, Gove et al., Phys. Rev. 105 (1957) 957;

Record comments
CVC and symmetry between electromagnetism and weak interaction. S = Q for nonleptonic decays of the strange particles.