Conformally exact results for SL(2, R)xSO(1, 1)d-2/SO(1, 1) coset models

Using the conformal invariance of the SL(2, R)xSO(1, 1)d-2/SO(1, 1) coset models we calculate the conformally exact metric and dilaton, to all orders in the 1/k expansion. We consider both vector and axial gauging. We find that these cosets represent two different space-time geometries: (2d black hole)xRd-2 for the vector gauging and (3d black string)xRd-3 for the axial one. In particular for d=3 and for the axial gauging one obtains the exact metric and dilaton of the charged black string model introduced by Horne and Horowitz. If the value of k is finite we find two curvature singularities which degenerate to one in the semi-classical k→∞ limit. We also calculate the reflection and transmission coefficients for the scattering of a tachyon wave and using the Bogoliubov transformation we find the Hawking temperature. (orig.)