Abstract
We derive the evolution equation for the density matrix of a UV- and IR- limited band of comoving momentum modes of the canonically normalized scalar degree of freedom in two examples of nearly de Sitter universes. Including the effects of a cubic interaction term from the gravitational action and tracing out a set of longer wavelength modes, we find that the evolution of the system is non-Hamiltonian and non-Markovian. We find linear dissipation terms for a few modes with wavelength near the boundary between system and bath, and nonlinear dissipation terms for all modes. The non-Hamiltonian terms in the evolution equation persist to late times when the scalar field dynamics is such that the curvature perturbation continues to evolve on super-Hubble scales.
Original language | English (US) |
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Article number | 083535 |
Journal | Physical Review D |
Volume | 98 |
Issue number | 8 |
DOIs | |
State | Published - Oct 15 2018 |
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics