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arXiv · hep-th/9710055

Variational Multi-Time Green's Functions for Nonequilibrium Quantum Fields

Mohamed Benarous
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Abstract

The time-dependent variational principle proposed by Balian and Veneroni is used to provide the best approximation to the generating functional for multi-time Green's functions of a set of (bosonic) observables $Q_{μ)$. By suitably restricting the trial spaces, the computation of the two-time Green's function, obtained by a second order expansion in the sources, is considerably simplified. This leads to a tractable formalism suited to quantum fields out of equilibrium. We propose an illustration on the finite temperature ${\bfΦ^4}$ theory in curved space and coupled to gravity.

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Mohamed Benarous. 1997-10-07. Variational Multi-Time Green's Functions for Nonequilibrium Quantum Fields. https://doi.org/10.1006/aphy.1998.5844

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