Spectrum of the Boltzmann collision operator for λϕ4 theory in the classical regime

Abstract

We analytically determine all the eigenvalues and eigenfunctions of the linearized Boltzmann collision operator (computed using Boltzmann statistics) in massless scalar λϕ4 theory. This is used to determine this system's shear viscosity and particle diffusion transport coefficients in analytical form. The corresponding relaxation time approximation for this linearized Boltzmann equation is also derived.