A Hamiltonian formalism is developed to describe the classical motion of a bag-type model for small oscillations of the boundary around a static configuration and to give an approximate quantization of the system. It is shown that in the case of the one-dimensional bag the method reproduces the exact form of the mass-squared operator, which is known from the light-cone quantization. The formalism is then applied to the study of a three-dimensional bosonic bag and in particular to the analysis of the $P$-wave excitations.

• Received 2 June 1975

DOI:https://doi.org/10.1103/PhysRevD.12.2407