On the Interaction of Elementarry 2 Particles. I.
By Hideki YUKAWA. (Read Nov. 17, 1934)
§1.Introduction At the present stage of the quantum theory little is known about the nature of interaction of elementary particles. Heisenberg considered the interaction of " Platzwechsel " between the neutron and the proton to be of importance to the nuclear structure.(1) Recently Fermi treated the problem of β-disintegration on the hypothesis of "neutrino "(2). 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 energies of neutrons and protons in the nucleus.(3) 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., a neutrino and an electron, but the energy liberated by the transition is taken up sometimes by another heavy particle, which in turn will be transformed from proton state into neutron state. If the probability of occurrence of the latter process is much larger than that of the former, the interaction between the neutron and the proton will be much larger 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 show that the interaction of heavy particles with this field is much larger than that of light particles with it.