Scattering of charged particles by magnetic strings

In this paper we consider the scattering of charged particles by magnetic strings for several configurations of the incident state and of the enclosed flux. We analyze the scattering of a plane wave by an infinite magnetic string and show that the scattering contribution arises from flux-dependent phase shifts followed by quantum diffusion. Then we report that the amplitude for the scattering of a wave packet of finite extension by a magnetic string becomes exponentially small as the width of the packet goes to zero. At the same time the phase at the center of the incident wave packet is progressively shifted by an amount proportional to the enclosed flux, as predicted on the basis of the quasiclassical approximation. We consider further the scattering by a pair of parallel strings carrying opposite fluxes and show that the probability pattern is affected by the magnetic fluxes mainly in the vicinity of a finite surface spanning the two strings. We finally discuss the relevance for the Aharonov-Bohm effect of the multivalued gauge transformations which eliminate the potentials from the field-free region. The results reported in this paper confirm the reality of the quantum effects of remote fluxes, and prove that the state of the electromagnetic field is not completely determined by the local knowledge of the field strengths.