On the rate theory for thermal soliton generation

The use of absolute rate theory is suggested for a simple description of the dynamics of thermally generated solitons in the underdamped regime. Rate theory is reformulated to describe thermal transitions between continuous states of nonlinear wave equations emphasizing the soliton or pseudoparticle interpretation. The final rate expression, which applies also to metastable states, is compared with that for the decay of unstable vacua in quantum field theory. As an example, the thermal generation rate of distant kink pairs on the Sine Gordon chain is calculated exactly and also within the semiclassical approximation.