On AdS/CFT duality in the twisted sector of string theory on AdS5 × S5/ℤ2 orbifold background

A bstract We consider type IIB string theory on an AdS 5 × S 5 /ℤ 2 orbifold background, which should be dual to 4d N N = 2 superconformal SU (N) × SU (N) gauge theory with two bi-fundamental hypermultiplets. The correlator of two chiral BPS operators from the twisted sector of this quiver CFT exhibits non-trivial dependence on the ’t Hooft coupling λ already in the planar limit. This dependence was recently determined using localisation and the expansion at large λ contains a subleading contribution proportional to ζ (3) λ − 3 / 2. We address the question of how to reproduce this correction on the string theory side by starting with the ζ (3) α ′ 3 term in the type IIB string effective action. We find a regular solution of type IIB supergravity which represents a resolution of the AdS 5 × S 5 /ℤ 2 orbifold and demonstrate that the relevant light twisted sector states may be identified as additional supergravity 2-form modes “wrapping” a finite 2-cycle in the resolution space. Reproducing the structure of the gauge theory result becomes more transparent in the large R -charge or BMN-like limit in which the resolved background takes a pp-wave form with the transverse space being a product of ℝ 4 and the Eguchi-Hanson space.