1202.1301 (Marco Drewes et al.)

Boltzmann Equations from First Principles without Gradient Expansion    [PDF]

Marco Drewes, Sebastian Mendizabal, Christoph Weniger

We show from first principles the emergence of classical Boltzmann equations
for a generic quantum field that couples to a collection of background fields
and sources. Our analysis is based on relativistic nonequilibrium quantum field
theory as described by the Kadanoff-Baym equations and does not rely on the
usual semi-classical approximations, i.e. on-shell condition,
close-to-equilibrium assumption, gradient expansion and the Kadanoff-Baym
ansatz. Instead, we find simple analytical solutions to the full Kadanoff-Baym
equations by using the Wentzel-Kramers-Brillouin (WKB) method, and discuss
under which circumstances Boltzmann behavior emerges.

View original: http://arxiv.org/abs/1202.1301