Comments on D-branes in AdS(3)

We study D-branes that preserve a diagonal SL(2) affine Lie algebra in stri ng theory on AdS(3). We find three classes of solutions, corresponding to t he following representations of SL(2): (1) degenerate, finite-dimensional r epresentations with half integer spin, (2) principal continuous series, (3) principal discrete series. We solve the bootstrap equations for the vacuum wave functions and discuss the corresponding open string spectrum. We argu e that from the point of view of the AdS/CFT correspondence, the above D-br anes introduce boundaries with conformal boundary conditions into the two-d imensional spacetime. Open string vertex operators correspond to boundary p erturbations. We also comment on the geometric interpretation of the branes . (C) 2001 Published by Elsevier Science B.V.