Optimal Gaussian approximation in the fluctuating field theory

N. B. Melnikov ; B. I. Reser

Trudy Matematicheskogo Instituta imeni V.A. Steklova, Differential equations and topology. II, Tome 271 (2010), pp. 159-180.

Résumé

We consider the problem of calculating the partition function given by the functional integral over an external field that fluctuates in space and in “time” $\tau\in[0,1/T]$ ($T$ is temperature). A method is presented for calculating such integrals with the help of the Gaussian approximation that takes into account dynamics and non-locality of the fluctuations. The method is based on the free energy minimum principle.

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