Researchers at Fermilab and other DOE-funded institutions have played a significant role in developing a comprehensive framework that explains nature's particle zoo.

Not surprisingly, the huge number of particles was referred to as the "particle zoo".

However, new hadrons were discovered, the 'particle zoo' grew from a few particles in the early 1930s and 1940s to several dozens of them in the 1950s.

In essence, preon theory tries to do for the Standard Model what the Standard Model did for the particle zoo that came before it.

It was referred to as the "particle zoo".

Dröscher first extended this to eight and claimed that this yields quantum electrodynamics along with the "particle zoo" of mesons and baryons.

At the time of the quark theory's inception, the "particle zoo" included, amongst other particles, a multitude of hadrons.

Now the Standard Model predicted that the particle zoo was nearly complete.

Among the particle theorists the highest status attached to the field theorists who developed new models to bring more order to the particle zoo.

Hypercharge was a concept developed in the 1960s, to organize groups of particles in the "particle zoo" and to develop ad-hoc conservation laws based on their observed transformations.