Chronology of Milestone Events in Particle Physics - SALAM 1968
Chronology of Milestone Events in Particle Physics

  Nobel prize to A. Salam awarded in 1979. Co-winners S. L. Glashow and S. Weinberg "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''  

SALAM 1968

Salam, A.;
Weak and Electromagnetic Interactions
Elementary Particle Theory (1968);

Reprinted in
J. L. Rosner, New Particles. Selected Reprints, Stony Brook, Am. Ass. of Physics Teachers (1981) 29.

One of the recurrent dreams in elementary particles physics is that of a possible fundamental synthesis between electromagnetism and weak interactions. The idea has its origin in the following shared characteristics:
1) Both forces affect equally all forms of matter-leptons as well as hadrons.
2) Both are vector in character.
3) Both (individually) possess universal coupling strengths
Since universality and vector character are features of a gauge-theory those shared characteristics suggest that weak forces just like the electromagnetic forces arise from a gauge principle. There of course also are profound differences: Electromagnetic coupling strength is vastly different from the weak. Quantitatively one may state it thus: if weak forces are assumed to have been mediated by intermediate bosons W, the boson mass would have to equal 137 Mp, in order that the (dimensionless) weak coupling constant gW2/4 equals e2/4
I shall approach this synthesis from the point of view of renormalization theory. I had hoped that would be able to report on weak and electromagnetic interactions throughout physics, but the only piece of work that is complete is that referring to leptonic interactions, so I will present only that today. Ward and I worked with these ideas intermittently, particularly the last section on renormalization of Yang-Mills theories. The material I shall present today, incorporating some ideas of Higgs-Kibble, was given in lectures (unpublished) at Imperial College. Subsequently I discovered that an almost identical development had been made by Weinberg who apparently was also unaware of Ward's and my work. (Extracted from the introductory part of the paper.).

Related references
More (earlier) information appears in
A. Salam and J. C. Ward, Nuovo Cim. 11 (1959) 568;
A. Salam and J. C. Ward, Phys. Lett. 13 (1964) 168;
A. Salam and J. C. Ward, Phys. Rev. 136 (1964) B763;
A. Salam, Phys. Rev. 127 (1962) 331;
See also
S. Weinberg, Phys. Rev. Lett. 19 (1967) 1264;

Particles studied
  W+ ex, mass
  W ex, mass

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Lagrangian for the electroweak synthesis. Salam-Ward version.
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