ABSTRACT
This chapter presents the classical hadron theory and then its quantization. It shows that the quantum hadron theory is equivalent to Quantum Chromodynamics in two dimensions. Dirac’s main idea was that in any physical state all except a finite number of the negative energy states are occupied. Since fermions obey the Pauli exclusion principle, only one particle can occupy a given state: decay into states of very low energy is forbidden because those states are occupied. In particular the vacuum is not the state containing no particles. Instead the vacuum is the state where all the negative energy states are occupied and the positive energy states are empty. The filled negative energy states in the vacuum is called the ‘Dirac Sea’. In principle a baryon can be in any of the configurations of renormalized dimension one: the ground state will be the one of least energy. The topologically non-trivial solutions of the theory-the solitons-describe baryons.
