Archive of historical materials
Talk: On the Interactions of Elementary Particles
OU1934-A3 (10 pages) Date: October 27, 1934
On October 27, Yukawa wrote in his diary: “From 2 pm I talked about the charged quantum theory in a small meeting room on the third floor. Returned home at 6 pm.” This is probably the manuscript of his lecture given at the meeting. The note has 10 pages, but it is not complete. In this note, Yukawa jotted down what he wanted to say in a lecture tone. However, from about the middle of the note, there are crossed-out sentences, which he probably decided to delete after some contemplation, and numbers with question marks at various places.
Yukawa started the lecture by saying, “The Fermi theory of beta decay I discussed earlier seems to explain the experiment results very well, but this theory cannot explain the interaction between neutrons and protons.” Yukawa used the analogy with electromagnetic interaction and stated that the neutron and proton exchange a new particle, charged quantum, and what is now called Yukawa potential emerges instead of Coulomb potential. In page 5, he worked on determining the wavelength and force of the new particle based on the data of mass defects and dependency on scattering speed. The new particle, charged quantum, is known today as a charged π meson. Yukawa began by giving the analogy, then solved the relativistic Klein-Gordon equation and determined the type of interaction between protons and neutrons. It is a brilliant lecture, indeed. (Written by Yutaka Hosotani)
