Field-theoretic Lagrangian with baglike solutions

A local Lagrangian involving self-coupled charged scalar fields is studied. The theory exhibits classical confined solutions which coincide with solutions of the analogous MIT bag model, even though no reference is made to a specific region of space in formulating the theory, and no auxiliary fields are used to generate the confining potential. Some of the quantum aspects of the theory are explored by means of a variational calculation, and it is shown that the trial wave functional which is used gives rise to the same form for the energy as is obtained in the cavity approximation to the bag model.