title: Generating functionals for harmonic expectation values of paths with fixed end points: Feynman diagrams for nonpolynomial interactions.
abstract: We introduce a general class of generating functionals for the calculation of quantum-mechanical expectation values of arbitrary functionals of fluctuating paths with fixed end points in configuration or momentum space. The generating functionals are calculated explicitly for the harmonic oscillator with time-dependent frequency, and used to derive a smearing formula for correlation functions of polynomial and nonpolynomial functions of time-dependent positions and momenta. This formula summarizes the effect of quantum fluctuations, and serves to derive generalized Wick rules and Feynman diagrams for perturbation expansions of nonpolynomial interactions.
authors.affiliation: Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Kleinert
authors.forename: A
authors.initials: A
authors.lastname: Pelster
authors.forename: M
authors.initials: M
authors.lastname: Bachmann