Common Integrals in Quantum Field Theory - Integrals That Can Be Approximated By The Method of Stationary Phase

Integrals That Can Be Approximated By The Method of Stationary Phase

A common integral is a path integral of the form

where is the classical action and the integral is over all possible paths that a particle may take. In the limit of small the integral can be evaluated in the stationary phase approximation. In this approximation the integral is over the path in which the action is a minimum. Therefore, this approximation recovers the classical limit of mechanics.

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