AdS3 Quantum Gravity via Finite-N Expansions

I will discuss the bulk mechanism of the stringy exclusion principle in the AdS3/CFT2 case. Consider the duality between  string theory on AdS3 × S3 × M4 and Sym^N(M4). At finite N, both the chiral-chiral spectrum and the number of the polar terms of the elliptic genus are finite. I will show that these finite-N spectra can be recovered by summing over the corresponding contribution from the  (AdS3xS3)/Z_k x M4 orbifolds. Although each orbifold contributes an infinite series, their sum reproduces the finite-N boundary data due to the large cancellations induced by the bosonic negative modes of the orbifold saddles.