ABSTRACT
The standard model of particle physics is the theory of the strong, the electromagnetic and the weak interactions. The strong interaction is the interaction among the quarks of different colors (there are three colors) and avors (six avors u,c, t,d,s,b), and they are mediated by eight gluons. It is an SU(3) gauge theory, called quantum chromodynamics (QCD), and the three colored states of every avor belong to the triplet representation of the SU(3)c. The gluons are the eight gauge bosons corresponding to the generators of the group SU(3)c. Colored states are conned, and hence, only color singlet states can exist in nature as free particles. Known color singlet states are baryons (made of three quarks) or mesons (made of quark–antiquark pairs). The strong nuclear force is the force between the protons and neutrons, which is a manifestation of the underlying SU(3)c interactions among the quarks, although with our present knowledge of the many-body problem it is almost impossible to derive the nuclear potential starting from QCD without any assumption.
