It is shown that Feynman's path integral can be written as a Fourier transform of a function defined on the classical phase space with the help of the star product recently introduced by Bayen, Flato, Fronsdal, Lichnerowicz, and Sternheimer. This gives a well-defined meaning to path integrals and may prove to be a useful tool in their actual evaluation.

• Received 14 December 1978

DOI:https://doi.org/10.1103/PhysRevD.20.414