Classical Kinetic Theory of Landau Damping for Self-interacting Scalar   Fields in the Broken Phase
  The classical kinetic theory of one-component self-interacting scalar fields is formulated in the broken symmetry phase and applied to the phenomenon of Landau damping. The domain of validity of the classical approach is found by comparing with the result of a 1-loop quantum calculation. 
A. Patkos, Zs. Szep