“…The sine-Gordon field theory and the associated massive Thirring model [1] are some of the best studied quantum field theories. In view of its connections to other important physical models, some of which in principle admit actual realizations in nature [2,3], a huge mass of important exact results have been obtained for this fascinating integrable system [4][5][6][7]. However, no less fascinating are the remarkable mathematical and physical properties of its soliton (or "solitary wave") solutions which have contributed, along the last decades, to turn the physics of solitons into a very active research topic.…”