Chronology of Milestone Events in Particle Physics - NISHIJIMA 1957
Chronology of Milestone Events in Particle Physics


Nishijima, K.;
Vanishing of the Neutrino Rest Mass
Phys. Rev. 108 (1957) 907;

The requirement that the mass of the neutrino be exactly zero may by satisfied by demanding invariance under many transformations besides the one proposed by Salam. One such, which involves a transformation on the muon (electron) field as well, leads to the selection rule: neutrinoless transitions involving an odd number of muons and an odd number of electrons are strictly forbidden. No such process has been observed. The theory of beta-decay is unaffected but, in muon decay, the predominant mode must be + e+ R L in order to obtain the observed spectrum, so that the theory must include two kinds of two-component neutrinos. If leptons are conserved, there will be two kinds of "lepton charge'', one carried by the muons and one group of neutrinos and the other by the electrons and the other type of neutrinos, and each will be conserved separately. (Science Abstracts, 1958, 1827. P. K. Kabir.).

Related references
See also
E. J. Konopinski and H. M. Mahmoud, Phys. Rev. 92 (1953) 1045;

  e qnc
  2e e+ qnc
  p p e qnc
  K+ + + e qnc
  K+ + e+ qnc
  Ko + e qnc
  Ko e+ qnc

Particles studied
  + qn
  e+ qn
  e qn

Record comments
Introduction of lepton-family-number conservation.
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