Strange quark

The first strange particle (a particle containing a strange quark) was discovered by George Rochester and Clifford Butler in Department of Physics and Astronomy, University of Manchester in 1947 (kaons), with the existence of the strange quark itself (and that of the up and down quarks) postulated in 1964 by Murray Gell-Mann and George Zweig to explain the eightfold way classification scheme of hadrons.

The first evidence for the existence of quarks came in 1968, in deep inelastic scattering experiments at the Stanford Linear Accelerator Center.

While studying these decays, Murray Gell-Mann (in 1953)[4][5] and Kazuhiko Nishijima (in 1955)[6] developed the concept of strangeness (which Nishijima called eta-charge, after the eta meson (η)) to explain the "strangeness" of the longer-lived particles.

Despite their work, the relationships between each particle and the physical basis behind the strangeness property remained unclear.

In 1961, Gell-Mann[7] and Yuval Ne'eman[8] independently proposed a hadron classification scheme called the eightfold way, also known as SU(3) flavor symmetry.