Magnetic Moments of Branes and Giant Gravitons

TL;DR

This paper explores how D0 branes and gravitons expand into branes in magnetic backgrounds, revealing a general phenomenon where particles can blow up into branes with matching quantum numbers and energies, even in less supersymmetric settings.

Contribution

It demonstrates the magnetic analogue of Myers' Dielectric Effect and shows the blowing up of particles into branes in various backgrounds, extending previous results to more general cases.

Findings

Particles expand into branes with magnetic fields.

Existence of classical two-sphere brane solutions matching quantum numbers.

Blowing up phenomenon is quite general across backgrounds.

Abstract

We study the magnetic analogue of Myers' Dielectric Effect and, in some cases, relate it to the blowing up of particles into branes, first investigated by Greevy, Susskind and Toumbas. We show that $D0$ branes or gravitons in M theory, moving in a magnetic four-form field strength background expand into a non-commutative two sphere. Both examples of constant magnetic field and non-constant fields in curved backgrounds generated by branes are considered. We find, in all cases, another solution, consisting of a two-brane wrapping a classical two-sphere, which has all the quantum numbers of the $D0$ branes. Motivated by this, we investigate the blowing up of gravitons into branes in backgrounds different from $AdS_m \times S^n$. We find the phenomenon is quite general. In many cases with less or even no supersymmetry we find a brane configuration which has the same quantum numbers and the same energy as a massless particle in supergravity.