Kinetic equation for a soliton gas - SOLITONS, COLLAPSES AND ...

Generalised kinetic equations for soliton gases with elasticcollisions El & Kamchatnov (PRL 2005)Main ingredients: (i) the speed of a free soliton S(η) and (ii) thephase shift ∆x η,µ = G(η, µ) due to the soliton-soliton collision.Introduce the spectral distribution function f (η) ≡ f (η, x, t) and themean speed of a ‘trial’ η- soliton s(η) ≡ s(η, x, t)Then the self-consistent definition of the soliton velocity s(η) in adense soliton gas with the spectral distribution f (η) is given by theintegral equations(η) = S(η) +∫ ∞0G(η, µ)[s(η) − s(µ)]f (µ)dµ ,Isospectrality implies the conservation equation for the spectraldistribution function f (η, x, t):f t + (sf ) x = 0 .Gennady ElKinetic equation for a soliton gas