Nobel prize to S. L. Glashow awarded in 1979. Co-winners S. Weinberg and A. Salam "for their contribution to the theory of the unified weak and electromagnetic interaction between elementary particles, including inter alia the prediction of the weak neutral current''
Weak and electromagnetic interactions of the leptons are examined under the hypothesis that the weak interactions are mediated by vector bosons. With only an isotopic triplet of leptons coupled to a triplet of vector bosons (two charged decay-intermediaries and the photon) the theory possesses no partial-symmetries. Such symmetries may be established if additional vector bosons or additional leptons are introduced. Since the latter possibility yields a theory disagreeing with experiment, the simplest
partially-symmetric model reproducing the observed electromagnetic and weak interactions of leptons requires the existence of at least four vector-boson fields (including the photon). Corresponding partially-conserved quantities suggest leptonic analogues to the conserved quantities associated with strong interactions: strangeness and isobaric spin.
Related references See also C. Fronsdal and S. L. Glashow, Phys. Rev. Lett. 3 (1959) 570;
J. Schwinger, Ann.Phys. 2 (1957) 407;
S. L. Glashow, Nucl. Phys. 10 (1959) 107;
R. P. Feynman and M. Gell-Mann, Phys. Rev. 109 (1958) 193;
M. Gell-Mann and M. Levi, Nuovo Cim. 16 (1960) 705;
G. Feinberg, Phys. Rev. 110 (1958) 1482;
J. Bernstein, M. Gell-Mann, and L. Michel, Nuovo Cim. 16 (1960) 560;
First introduction of the neutral intermediate boson.