Hylomorphic solitons and charged Q-balls: existence and stability
  In this paper we give an abstract definition of solitary wave and soliton and we develop an abstract existence theory. This theory provides a powerful tool to study the existence of solitons for the Klein-Gordon equations as well as for gauge theories. Applying this theory, we prove the existence of a continuous family of stable charged Q-balls. 
Vieri Benci, Donato Fortunato
math-ph math.MP