Chronology of Milestone Events in Particle Physics - YUKAWA 1935
Chronology of Milestone Events in Particle Physics

  Nobel prize to H. Yukawa awarded in 1949 "for his prediction of the existence of mesons on the basis of theoretical work on nuclear forces''  


Yukawa, H.;
On the Interaction of Elementary Particles
Proc.Phys.Math.Soc.Jap. 17 (1935) 48;

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Reprinted in
R. T. Beyer. Foundation of Nuclear Physics, Dover, New York (1949).
D. M. Brink. Nuclear Forces. Pergamon Press (1965) 214.

At the present stage of the quantum theory little is known about the nature of interactions of elementary particles. Heisenberg considered the interaction of "Platzwechsel'' between the neutron and the proton to be of importance to the nuclear structure.
Recently Fermi treated the problem of -disintegration on the hypothesis of "neutrino.'' According to this theory, the neutron and the proton can interact by emitting and absorbing a pair of neutrino and electron. Unfortunately the interaction energy calculated on such assumption is much too small to account for the binding energy of neutrons and protons in the nucleus. To remove this defect, it seems natural to modify the theory of Heisenberg and Fermi in the following way. The transition of a heavy particle from neutron state to proton state is not always accompanied by the emission of light particles, i.e. neutrino and an electron, but energy liberated by the transition is taken up sometimes by another particle, which in turn will be transformed from proton state into neutron state. If the probability of occurrence of the latter process is much large that of the former, the interaction between the neutron and the proton will be much large than in the case of Fermi, whereas the probability of emission of light particles is not affected essentially.
Now such interaction between the elementary particles can be described by means of a field of force, just as the interaction between the charged particles is described by the electromagnetic field. The above considerations shows that the interaction of heavy particles with this field is much larger than that of light particles with it.
In the quantum field theory this field should be accompanied by a new sort of quantum, just as the electromagnetic field is accompanied by the photon.
In this paper the possible nature of this field and the quantum accompanying it will be discussed briefly and also their bearing on the nuclear structure will be considered.
Besides such an exchange force and ordinary electric and magnetic forces there may be other forces between the elementary particles, but we disregard the latter for the moment.
Fuller account will be made in the next paper.

Related references
See also
W. Heisenberg, Z. Phys. 77 (1932) 1;
W. Heisenberg, Z. Phys. 78 (1932) 156;
W. Heisenberg, Z. Phys. 80 (1933) 587;
E. Fermi, Z. Phys. 88 (1934) 161;
I. E. Tamm, Nature 133 (1934) 981;
D. D. Iwanenko, Nature 133 (1934) 981;
Analyse data from
T. W. Bonner, Phys. Rev. 45 (1934) 606;

Particles studied
  ± ex, qn, mass

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Yukawa field theory of nuclear forces. Prediction of heavy quanta, the pion particles, as mediators of strong interactions.
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