Does it refer to the components of the atomic nucleus

Introduction

(A proton and an antiproton collide at high energy, producing a pair of almost free quarks. )

In 1964, American physicists Murray Gell-Mann and G. Zweig each independently proposed that hadrons such as neutrons and protons are composed of a more basic unit-Quark ( That is, composed of quarks). They have fractional charge, which is 2/3 or -1/3 times the basic charge, and their spin is 1/2.