Initial time singularities and admissible initial states for a system of coupled scalar fields
Abstract
We discuss the problem of initial states for a system of coupled scalar fields out of equilibrium in the one-loop approximation. The fields consist of classical background fields, taken constant in space, and quantum fluctuations. If the initial state is the adiabatic vacuum, i.e., the ground state of a Fock space of particle excitations that diagonalize the mass matrix, the energy-momentum tensor is infinite at t=0, its most singular part behaves as 1/t. When the system is coupled to gravity this presents a problem that we solve by a Bogoliubov transformation of the naive initial state. As a side result we also discuss the canonical formalism and the adiabatic particle number for such a system. Most of the formalism is presented for Minkowksi space. Embedding the system and its dynamics into a flat FRW universe is straightforward and we briefly address the essential modifications.
Keywords
Cite
@article{arxiv.0910.1128,
title = {Initial time singularities and admissible initial states for a system of coupled scalar fields},
author = {Jurgen Baacke and Nina Kevlishvili},
journal= {arXiv preprint arXiv:0910.1128},
year = {2010}
}
Comments
26 pages, no figures; typos corrected, added 6 paragraphs et the end of section 3, and 1 paragraph at the end of section 5