Feynman graphs for non-Gaussian measures

Sidi H. Djah, Hanno Gottschalk, Habib Ouerdiane
January 12, 2005
Partition- and moment functions for a general (not necessarily Gaussian) functional measure that is perturbed by a Gibbs factor are calculated using generalized Feynman graphs. From the graphical calculus, a new notion of Wick ordering arises, that coincides with orthogonal decompositions of Wiener-Itô type only if the measure is Gaussian. Proving a generalized linked cluster theorem, we show that the logarithm of the partition function can be expanded in terms of connected Feynman graphs ("linked cluster theorem").

perturbation theory, Feynman diagrams, Wick ordering