Spectrum of Large N Gauge Theory from Supergravity

TL;DR

This paper investigates the spectrum of large N gauge theory via supergravity duality, revealing a discrete, evenly spaced spectrum and insights into spacetime regions behind the horizon.

Contribution

It demonstrates the discrete spectrum of large N gauge theory on R x S^3 and explores the spacetime regions described by the gauge theory.

Findings

Spectrum is discrete and evenly spaced

Number of states is less than naive Bekenstein-Hawking extrapolation

Gauge theory describes regions behind and in front of the horizon

Abstract

Recently, Maldacena proposed that the large N limit of the N=4 supersymmetric gauge theory in four dimensions with U(N) gauge group is dual to the type IIB superstring theory on AdS_5 x S^5. We use this proposal to study the spectrum of the large N gauge theory on R x S^3 in a low energy regime. We find that the spectrum is discrete and evenly spaced, and the number of states at each energy level is smaller than the one predicted by the naive extrapolation of the Bekenstein-Hawking formula to the low energy regime. We also show that the gauge theory describes a region of spacetime behind the horizon as well as the region in front.