Microstates at the boundary of AdS

TL;DR

This paper constructs specific perturbations in the D1D5 brane system that correspond to chiral algebra actions, revealing a non-gauge deformation at the boundary between AdS and asymptotic infinity, with implications for microstates.

Contribution

It explicitly constructs and analyzes boundary perturbations in the D1D5 system, clarifying their gauge nature and physical significance at the AdS boundary.

Findings

Perturbations are pure gauge in the AdS region.

Non-gauge deformation occurs at the 'neck' between AdS and infinity.

Implications for microstates at the cap.

Abstract

The bound states of the D1D5 brane system have a known gravitational description: flat asymptotics, an anti-de Sitter region, and a 'cap' ending the AdS region. We construct perturbations that correspond to the action of chiral algebra generators on Ramond ground states of D1D5 branes. Abstract arguments in the literature suggest that the perturbation should be pure gauge in the AdS region; our perturbation indeed has this structure, with the nontrivial deformation of the geometry occurring at the 'neck' between the AdS region and asymptotic infinity. This 'non-gauge' deformation is needed to provide the nonzero energy and momentum carried by the perturbation. We also suggest implications this structure may have for the majority of microstates which live at the cap.