Quantum bags at strong coupling

We examine the effect of quantum fluctuations on the formation of nontopological solitons in a relativistic field theory containing N fermions and a single scalar field. We present the exact large-N solution, valid for arbitrary Yukawa coupling g. We find that this theory supports nontopological solitons, or bags, which are bound states of N fermions. Because of the effects of the Dirac sea, these quantum solitons differ dramatically from those of the classical theory. In particular, for large g, the energy of the quantum solitons is proportional to g, the binding energy remains small, and the bags remain shallow. Thus, quantum corrections invalidate the classical picture of tightly bound fermions inside deep bags.