WEYL SPACETIMES AND WORMHOLES IN D-DIMENSIONAL EINSTEIN AND DILATON GRAVITY

Static, axially symmetric fields are considered in D-dimensional Einst ein (Abelian gauge) dilaton gravity, with arbitrary values of the dila ton coupling constant (l)ambda. Its special cases correspond to the fi eld limit of string theory (lambda(2) = 1/(D - 2)) and D-dimensional g eneral relativity (lambda = 0). A class of Weyl-type solutions, depend ing on three harmonic functions of two variables, is obtained. Among t hem we select a class of solutions which can be attributed to traversa ble wormholes with singular rings at their necks; the ring points comb ine the properties of twofold branching points and those of cosmic str ings. Under natural additional requirements, (i) such wormholes have n ecessarily positive masses as viewed from both asymptotics and (ii) th eir characteristic length scale in the large charge limit (GM(2) << Q( 2)) is of the order of the 'classical radius' Q(2)/M.