D.E. Pelinovsky and R.E. White

Localized structures on librational and rotational travelling waves in the sine-Gordon equation

Proc. R. Soc. A 476: 20200490 (18 pages)

Abstract:
We derive exact solutions to the sine-Gordon equation describing localized structures on the background of librational and rotational travelling waves. In the case of librational waves, the exact solution represents a localized spike in space-time coordinates (a rogue wave) which decays to the periodic background algebraically fast. In the case of rotational waves, the exact solution represents a kink propagating on the periodic background and decaying algebraically in the transverse direction to its propagation. These solutions model the universal patterns in the dynamics of uxon condensates in the semi-classical limit. The different dynamics are related to modulational instability of the librational waves and modulational stability of the rotational waves.

Keywords:
sine-Gordon equation, travelling waves, modulational instability, rogue waves, semiclassical dynamcis.