ABSTRACT
This chapter describes the idea that the baryon is a soliton, essentially made up of an infinite number of mesons. But this seems to contradict the simple and successful picture of the baryon as a bound state of quarks. There are many attempts to do compute the spectrum by direct numerical simulation of Quantum Chromodynamics (QCD), but they have to yet to surmount many obstructions. For example, the asymptotic freedom of QCD implies that the energy of all physical states are exponentially small compared to the cut-off. Extra-ordinary accuracy is required of all direct numerical computations of the energy, a problem that is only exacerbated by the large number of degrees of freedom in the system. The valence parton model assumes that the proton is made of N partons which are fermions transforming under the fundamental representation of color. The ground state of a many boson system can often be described by mean field theory.
