Abstract A direct approach to perturbation theory for the nonlinear Schr?dinger equation is developed based on the separation of variables. The first-order effects of perturbation on a bright soliton, i.e. the slow time dependence of soliton parameters and the first-order correction are derived.
Received: 20 May 2004
Revised: 30 June 2004
Accepted manuscript online:
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