A refined notion of arithmetically equivalent number fields, and curves with isomorphic Jacobians

Abstract

We construct examples of number fields which are not isomorphic but for which their adele groups, the idele groups, and the idele class groups are isomorphic. We also construct examples of projective algebraic curves which are not isomorphic but for which their Jacobian varieties are isomorphic. Both are constructed using an example in group theory provided by Leonard Scott of a finite group G and subgroups H1 and H2 which are not conjugate in G but for which the G-module Z[G/H1] is isomorphic to Z[G/H2].