Renormalized scalar propagator around a dispiration

Abstract

The renormalized Feynman propagator for a scalar field in the background of a cosmic dispiration (a disclination plus a screw dislocation) is derived, opening a window to investigate vacuum polarization effects around a cosmic string with dislocation, as well as in the bulk of an elastic solid carrying a dispiration. The use of the propagator is illustrated by computing vacuum fluctuations. In particular it is shown that the dispiration polarizes the vacuum giving rise to an energy momentum tensor which, as seen from a local inertial frame, presents non vanishing off-diagonal components. Such a new effect resembles that where an induced vacuum current arises around a needle solenoid carrying a magnetic flux (the Aharonov-Bohm effect), and may have physical consequences. Connections with a closely related background, namely the spacetime of a spinning cosmic string, are briefly addressed.