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arXiv · 0910.1128

Initial time singularities and admissible initial states for a system of coupled scalar fields

Jurgen Baacke·Nina Kevlishvili
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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.

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Jurgen Baacke, Nina Kevlishvili. 2009-12-24. Initial time singularities and admissible initial states for a system of coupled scalar fields. https://doi.org/10.1103/physrevd.81.023509

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