Squashed Giants: Bound States of Giant Gravitons

TL;DR

This paper studies how giant gravitons in a maximally supersymmetric type IIB plane-wave background deform under a constant NSNS B-field, revealing a bound state interpretation and analyzing stability and fluctuations.

Contribution

It introduces the concept of squashed giant gravitons as bound states of spherical three-branes and D-strings in a B-field background, analyzing their stability and fluctuation spectrum.

Findings

Giant gravitons deform into squashed three-spheres under B-field influence.

The squashed giant is a bound state of a three-brane and D-strings.

The stability of the squashed giant depends on the B-field magnitude.

Abstract

We consider giant gravitons in the maximally supersymmetric type IIB plane-wave, in the presence of a constant NSNS B-field background. We show that in response to the background B-field the giant graviton would take the shape of a deformed three-sphere, the size and shape of which depend on the B-field, and that the giant becomes classically unstable once the B-field is larger than a critical value B_{cr}. In particular, for the B-field which is (anti-)self-dual under the SO(4) isometry of the original giant S^3, the closed string metric is that of a round S^3, while the open string metric is a squashed three-sphere. The squashed giant can be interpreted as a bound state of a spherical three-brane and circular D-strings. We work out the spectrum of geometric fluctuations of the squashed giant and study its stability. We also comment on the gauge theory which lives on the brane (which is generically a noncommutative theory) and a possible dual gauge theory description of the deformed giant.