ON A GRAVITATIONAL AHARONOV-BOHM EFFECT

In this article we study the properties of certain quantum systems outside a rotating cosmic gauge string. It is shown that particle energies couple to the angular momentum density in the string, even though the particles are constrained only to move outside the string core where the Riemannian curvature vanishes identically. This effect may be looked upon as a gravitational analog of the Aharanov-Bohm effect. Due to the coupling of the particle energy to the angular momentum density in the string, it is shown that the angular momentum spectrum of the quantum particle is shifted by a constant amount. This, it is argued, will give rise to an nonvanishing angular momentum density in the quantum vacuum outside the rotating string. It is also shown that a quantum particle might experience an infinite blueshift in the presence of closed timelike curves outside such a string.