The discovery of new elementary particles began to take place between 1932 and 1947. The first of these discoveries was the neutrino, a theoretical solution by Italian physicist Enrico Fermi proposed in 1933 to justify some hitherto inexplicable results; but the confirmation of the particle’s existence did not come experimentally until twenty years later.
Another important particle proposed in 1935 by the Japanese physicist Hideki Yukawa was the photon. He postulated that this particle was capable of mediating interactions between fields (in the electromagnetic field the photon was already known), but there could be other particles that mediate other interactions, after all, it is photons that inform a charged particle of the existence of another, to know whether to attract or repel.
In addition to the photon, the first particle of this type was the pion, discovered in 1947 by a team of physicists, including the Brazilian César Lattes. This year, a set made up of fourteen elementary particles, identified theoretically or experimentally, was completed.
All particles had a perfect definition in the structure of matter, except the muon and antimuon, giving physicists hope based on the idea that the microscopic universe was fully discovered and mapped, but since in physics nothing is absolute and everything is relative, the certainties were soon undone.
Twenty years after the discovery of the pion, starting from a meticulous study of cosmic ray photographs and the remarkable technological advance of particle accelerators, new elementary particles continued to be discovered (there were approximately two hundred), which worried the researchers, after all, until the end of the 19th century they imagined that there was only a single fundamental particle, and so there was no reason for so many elementary particles.
Organizing so many particles
Realizing that it was necessary to organize such a proliferation of elementary particles and reduce this number, physicists began to look for bases to support such an organization. The first step was to identify similarities or regularities in the properties of these particles so that it was possible to group them in order to find points in common.
They then identified that in the convergence between the particles Λ° and π+, another type of particle must have appeared before the branch in O. This is because it does not appear, because its lifetime is so short that it does not leave a trace, or this trace is so small that it reduces to the point where the particles intersect.
In this way, it was possible to map them and identify their similarities, making it possible to organize the chaos.
In 1964, physicists Georg-Zweig and Muray Gell-Man independently concluded that a large part of the particles considered elementary were composed of other particles, which were elementary (or until proven otherwise).