The Enhancon and N=2 Gauge Theory/Gravity RG Flows

TL;DR

This paper explores ten-dimensional supergravity solutions modeling RG flows from N=4 to N=2 supersymmetric Yang-Mills theory, revealing the enhancon mechanism where gauge couplings diverge and extra massless states emerge.

Contribution

It identifies the enhancon ring as a locus of massless states and proposes excising the supergravity solution inside this ring, advancing understanding of gauge/gravity duality.

Findings

Enhancon ring corresponds to vacua with massless degrees of freedom.

Supergravity solutions match one-loop gauge coupling behavior.

SL(2,Z) duality relates different vacua on the enhancon ring.

Abstract

We study the family of ten dimensional type IIB supergravity solutions corresponding to renormalisation group flows from N=4 to N=2 supersymmetric Yang-Mills theory. Part of the solution set corresponds to a submanifold of the Coulomb branch of the gauge theory, and we use a D3-brane probe to uncover details of this physics. At generic places where supergravity is singular, the smooth physics of the probe yields the correct one-loop form of the effective low energy gauge coupling. The probe becomes tensionless on a ring at finite radius. Supergravity flows which end on this ``enhancon'' ring correspond to the vacua where extra massless degrees of freedom appear in the gauge theory, and the gauge coupling diverges there. We identify an SL(2,Z) duality action on the enhancon ring which relates the special vacua, and comment on the massless dyons within them. We propose that the supergravity solution inside the enhancon ring should be excised, since the probe's tension is unphysical there.