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

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 ${\mathbf{\Phi }}^4$ theory in curved space and coupled to gravity.

20 pages

References in corpus (3)

• Nonequilibrium Quantum Dynamics Of Disoriented Chiral Condensates
• Can Disordered Chiral Condensates Form? A Dynamical Perspective
• Variational approximation for two-time correlation functions in ${\Phi }^4$ theory : optimization of the dynamics

Cited by in corpus (4)

• Nonequilibrium Quantum Dynamics of Second Order Phase Transitions
• On the anomalous density for Bose gases at finite temperature
• Self-consistent theory of Bose-Einstein condensate with impurity at finite temperature
• BEC From a Time-Dependent Variational Point of View