Superstring theory on AdS2×S2 as a coset supermanifold

We quantize the superstring on the AdS2×S2 background with Ramond–Ramond flux using a PSU(1,1|2)/U(1)×U(1) sigma model with a WZ term. One-loop conformal invariance of the model is guaranteed by a general mechanism which holds for coset spaces G/H where G is Ricci-flat and H is the invariant locus of a Z4 automorphism of G. This mechanism gives conformal theories for the PSU(1,1|2)×PSU(2|2)/SU(2)×SU(2) and PSU(2,2|4)/SO(4,1)×SO(5) coset spaces, suggesting our results might be useful for quantizing the superstring on AdS3×S3 and AdS5×S5 backgrounds.