Decay of discrete nonlinear Schrödinger breathers through inelastic multiphonon scattering

We consider the long-time evolution of weakly perturbed discrete nonlinear Schrödinger breathers. While breather growth can occur through nonlinear interaction with one single initial linear mode, breather decay is found to require excitation of at least two independent modes. All growth and decay processes of lowest order are found to disappear for breathers larger than a threshold value.