Strings on Orbifolded PP-waves

TL;DR

The paper extends the pp-wave limit of AdS/CFT to Z_M orbifolds by quantizing the Green-Schwarz string on the orbifolded pp-wave and matching its twisted-sector spectra to operators in an N=2 quiver gauge theory. The authors derive twisted boundary conditions on the world-sheet, construct gauge-theory operators using Z_M projectors, and show that the string spectrum agrees with gauge theory results up to order $g_{YM}^2$, including correct level matching and momentum shifts from Wilson-line factors. This strengthens the AdS/CFT correspondence in less supersymmetric settings and clarifies how orbifold geometry and twisted sectors are encoded in the dual gauge theory. They also outline generalizations to non-abelian and non-supersymmetric orbifolds, suggesting broad applicability of the duality in pp-wave limits.

Abstract

We show that the string spectrum in the pp-wave limit of AdS_5\times S^5/Z_M (orbifolded pp-wave) is reproduced from the N=2 quiver gauge theory by quantizing the Green-Schwarz string theory on the orbifolded pp-wave in light cone gauge. We find that the twisted boundary condition on the world-sheet is naturally interpreted from the viewpoint of the quiver gauge theory. The correction of order g_{YM}^2 to the gauge theory operators agrees with the result in its dual string theory. We also discuss strings on some other orbifolded pp-waves.