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Variational Approximations for Correlation Functions in Quantum Field Theories

✍ Scribed by Cécile Martin

Publisher
Elsevier Science
Year
1999
Tongue
English
Weight
381 KB
Volume
278
Category
Article
ISSN
0003-4916

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✦ Synopsis

Applying the time-dependent variational principle of Balian and Ve ne roni, we derive variational approximations for multi-time correlation functions in 8 4 field theory. We assume first that the initial state is given and characterized by a density operator equal to a Gaussian density matrix. Then, we study the more realistic situation where only a few expectation values are given at the initial time and we perform an optimization with respect to the initial state. We calculate explicitly the two-time correlation functions with two and four field operators at equilibrium in the symmetric phase.

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