Non-equilibrium statistical field theory for classical particles: Non-linear structure evolution with first-order interaction

Understand

We calculate the power spectrum of density fluctuations in the statistical non-equilibrium field theory for classical, microscopic degrees of freedom to first order in the interaction potential.

• We specialise our result to cosmology by choosing appropriate initial conditions and propagators and show that the non-linear growth of the density power spectrum found in numerical simulations of cosmic structure evolution is reproduced well to redshift zero and for arbitrary wave numbers.
• The main difference of our approach to ordinary cosmological perturbation theory is that we do not perturb a dynamical equation for the density contrast.
• Rather, we transport the initial phase-space distribution of a canonical particle ensemble forward in time and extract any collective information from it at the time needed.