How did the search for particles which ain’t present in substances start?

How they hoped that pions are carriers of the strong interaction…

For the first three decades of the XX century, the idea had been formed that interaction between electrically charged particles is due to the exchange of quanta of the electromagnetic field, i.e., photons. Similarly, in 1934, Hideki Yukawa had predicted a new particle, a quantum of the nuclear field. According to his hypothesis, the interaction between nucleons is a result of the emission and absorption of particles named mesons. Then they have began a vigorous quest and, in 1937, in cosmic rays, Anderson and Neddermeyer have discovered a new particle with the mass value close to what was expected. Initially, it was thought that is a meson predicted by Yukawa, but a more detailed study of properties of that particle have shown that interacts with nucleons not as strong as it should be for the carrier of nuclear interactions — that is not being captured by nuclei and decays emitting electrons. The discovered particle was named muon. In 1947, another particle was discovered, which seemed to be that quantum of the nuclear field as this strongly interacts with nucleons. This was named pion, but later it has become clear that Yukawa’s idea is untrue.

Pions  were considered to be carriers of the strong interaction

It turned out that the role of mediation in the strong interaction is played by gluons, not pions.


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