A study of open strings ending on giant gravitons, spin chains and integrability

TL;DR

This paper investigates open strings attached to giant gravitons in AdS/CFT, revealing integrable spin chain descriptions, null geodesic limits, and an instability in long strings caused by Ramond-Ramond backgrounds.

Contribution

It provides a detailed analysis of open string spectra, their dual spin chain models, and uncovers an instability affecting integrability in the presence of Ramond-Ramond fields.

Findings

Identification of null geodesics along giant gravitons

Numerical evidence for integrability of the open spin chain

Discovery of a continuum spectrum instability in long strings

Abstract

We systematically study the spectrum of open strings attached to half BPS giant gravitons in the N=4 SYM AdS/CFT setup. We find that some null trajectories along the giant graviton are actually null geodesics of AdS_5x S^5, so that we can study the problem in a plane wave limit setup. We also find the description of these states at weak 't Hooft coupling in the dual CFT. We show how the dual description is given by an open spin chain with variable number of sites. We analyze this system in detail and find numerical evidence for integrability. We also discover an interesting instability of long open strings in Ramond-Ramond backgrounds that is characterized by having a continuum spectrum of the string, which is separated from the ground state by a gap. This instability arises from accelerating the D-brane on which the strings end via the Ramond-Ramond field. From the integrable spin chain point of view, this instability prevents us from formulating the integrable structure in terms of a Bethe Ansatz construction.