On the ground state of the Hamiltonian in the simplest model of quantum-field theory

Goldstone (Nuovo Cimento, 19, 154 (1961)) first considered an example of a quantum-field theory with a degenerate ground state. In the present paper a detailed analysis is made fromthis point of view of the simplest example of quantum-field theory in two-dimensional space-time; the absence of nontrivial divergences enables one to dispense with renormal- ization theory and the theory therefore gains in cogency and lucidity.