Graviton Propagators in Supergravity and Noncommutative Gauge Theory

TL;DR

This paper studies the behavior of graviton propagators in a supergravity background dual to noncommutative gauge theory, revealing that the propagator mimics a 4D massless graviton and that boundary conditions influence Kaluza-Klein modes.

Contribution

It introduces a boundary condition approach at the noncommutative scale and analyzes its effects on graviton and Kaluza-Klein mode propagators in the dual gauge theory.

Findings

Graviton propagator behaves as a 4D massless graviton.

Neumann boundary condition is appropriate at the noncommutative boundary.

Kaluza-Klein modes' non-analytic behaviors are largely unaffected.

Abstract

We investigate the graviton propagator in the type IIB supergravity background which is dual to 4 dimensional noncommutative gauge theory. We assume that the boundary is located not at the infinity but at the noncommutative scale where the string frame metric exhibits the maximum. We argue that the Neumann boundary condition is the appropriate boundary condition to be adopted at the boundary. We find that the graviton propagator behaves just as that of the 4 dimensional massless graviton. On the other hand, the non-analytic behaviors of the other Kaluza-Klein modes are not significantly affected by the Neumann boundary condition.