Quantization of the Type II superstring in a curved six-dimensional background

A sigma model action with N = 2 D = 6 superspace variables is constructed f or the Type II superstring compactified to six curved dimensions with Ramon d-Ramond flux. The action can be quantized since the sigma model is linear when the six-dimensional space-time is flat. When the six-dimensional space -time is AdS(3) X S-3, the action reduces to one found earlier with Vafa an d Witten. (C) 2000 Elsevier Science B.V. All rights reserved.