Gauge invariance of the Landau nonlinear damping decrement of Bose excitations in a quark–gluon plasma: Part I

A kinetic equation for interacting longitudinal waves (plasmons) is derived based on the Yang–Mills equation and on the dynamic equations describing the behavior of a quark–gluon plasma in the quasi-classical limit. Using effective Ward identities, the derived Landau nonlinear damping decrement is proved to be gauge invariant.