Resonance structures in kink-antikink collisions in a deformed sine-Gordon model

Abstract

We study kink-antikink collisions in a model which interpolates smoothly between the completely integrable sine-Gordon theory, the 4 model, and a 6-like model with three degenerate vacua. We find a rich variety of behaviours, including integrability breaking, resonance windows with increasingly irregular patterns, and new types of windows near the 6-like regime. False vacua, extra kink modes and kink fragmentation play important roles in the explanations of these phenomena. Our numerical studies are backed up by detailed analytical considerations.