Q-balls

A large family of field theories in 3+1 dimensions contains a new class of extended objects. The existence of these objects depends on (among other conditions) the existence of a conserved charge, Q, associated with an ungauged unbroken continuous internal symmetry. These objects are spherically symmetric, and for large Q their energies and volumes grow linearly with Q; thus they act like homogeneous balls of ordinary matter, with Q playing the role of particular number. This paper proves the fundamental existence theorem for these Q-balls, computes their elementary properties, and finds their low-lying excitations. (orig.)