Supergravity pp-wave solutions with 28 and 24 supercharges

TL;DR

This work presents a systematic classification of pp-wave solutions in type IIA and IIB supergravity with augmented supersymmetry, uncovering a two-parameter IIB family preserving 28 supercharges and multiple 24-supercharge families across both theories. The authors develop a projector-based method that analyzes dilatino and gravitino variations to identify viable flux configurations, then verify consistency with the equations of motion; they show 28 is the maximal count for pp-waves in ten dimensions. Through T-duality, they generate nonsingular flows from AdS near-horizon geometries to nontrivial UV geometries, interpretable as irrelevant perturbations in AdS-CFT and linked to BMN-like sectors. The results illuminate the structure of supersymmetric wave backgrounds, establish a general bound on supersymmetry enhancement, and propose avenues for connecting these exact solutions to dual field theories and nontrivial RG flows.

Abstract

We conduct an exhaustive search for solutions of IIA and IIB supergravity with augmented supersymmetry. We find a two-parameter family of IIB solutions preserving 28 supercharges, as well as several other IIA and IIB families of solutions with 24 supercharges. Given the simplicity of the pp-wave solution, the algorithm described here represents a systematic way of classifying all such solutions with augmented supersymmetry. By T-dualizing some of these solutions we obtain exact non-pp wave supergravity solutions (with 8 or 16 supercharges), which can be interpreted as perturbations of the AdS-CFT correspondence with irrelevant operators.