A topological model of the Aharonov-Bohm scattering is presented, where the
usual set-up is modelled by a genus-one Riemann surface with two cusps, i.
e. leaks infinitely far away. This constant negative-curvature surface is u
niformized by the Hecke congruence subgroup Gamma(0)(11) of the modular gro
up. The fluxes through the holes are described by the even Dirichlet charac
ter for Gamma(0)(11). The scattering matrix having only off-diagonal elemen
ts (no reflection) is calculated. The fluctuating part of the off-diagonal
entries shows a non-trivial dependence on the fluxes as well. The scatterin
g resonances are related to the non-trivial zeros of a Dirichlet L-function
. The chaotic nature of the scattering is related to the distribution of pr
imes in arithmetical progressions.