Breather kink-antikink-pair conversion in the driven sine-Gordon system

Breather excitations in the sine-Gordon equation influenced by constant driving forces are investigated—large driving forces cause the breather to split into a kk― (2π kink-2π antikink) pair while for small driving forces the breather excitations enter stationary modes. A perturbation method and a potential-energy argument yields expressions for the threshold for breather decomposition. Good agreement between theory and numerical results is found when the initial phase (θ) of the breather is either 0 or π. For θ≅π / 2 and θ≅3π / 2 the deviation gets larger.