Title: Kinetic approach to relativistic dissipation,
Abstract: Despite a long record of intense efforts, the basic mechanisms by which
dissipation emerges from the microscopic dynamics of a relativistic fluid still
elude a complete understanding. In particular, no unique pathway from kinetic
theory to hydrodynamics has been identified as yet, with different approaches
leading to different values of the transport coefficients. In this Letter, we
approach the problem by matching data from lattice kinetic simulations with
analytical predictions. Our numerical results provide neat evidence in favour
of the Chapman-Enskog procedure, as suggested by recently theoretical analyses,
along with qualitative hints at the basic reasons why the Chapman-Enskog
expansion might be better suited than Grad's method to capture the emergence of
dissipative effects in relativistic fluids.