  Representations of the Klein-Gordon and Dirac propagators are determined in a
$N$ dimensional conical background for massive fields twisted by an arbitrary
angle $2\pi\sigma$. The Dirac propagator is shown to be obtained from the
Klein-Gordon propagator twisted by angles $2\pi\sigma\pm {\cal D}/2$ where
${\cal D}$ is the cone deficit angle. Vacuum expectation values are determined
by a point-splitting method in the proper time representation of the
propagators. Analogies with the Aharonov-Bohm effect are pointed out throughout
the paper and a conjecture on an extension to fields of arbitrary spin is
given.
