A gravitational analogue of the Aharonov-Bohm effect, L.H. Ford, Alexander Vilenkin, J. Phys. A: Math. Gen 14(1981) pp-2353-2357
Abstract. It is shown that particles constrained to move in a region where the Riemann tensor vanishes may nonetheless exhibit physical effects arising from non-zero curvature in a region from which they are excluded. This is a gravitational analogue of the Aharonov-Bohm effect.