RG Interfaces from Double-Trace Deformations

TL;DR

This paper investigates interface conformal field theories created by double-trace deformations, analyzing their properties through large N expansion and holography, and computing defect data and conformal anomalies.

Contribution

It introduces a large N expansion method for interface CFTs with double-trace deformations and confirms holographic predictions with explicit calculations.

Findings

Computed defect CFT data using large N expansion.

Calculated conformal anomaly coefficients for spherical interfaces.

Verified agreement between field theory and holographic results.

Abstract

We study a class of interface conformal field theories obtained by taking a large $N$ CFT and turning on a relevant double-trace deformation over half space. At low energies, this leads to a conformal interface separating two CFTs which are related by RG flow. We set up the large $N$ expansion of these models by employing a Hubbard-Stratonovich transformation over half space, and use this approach to compute some of the defect CFT data. We also calculate the free energy of the theory in the case of spherical interface, which encodes a conformal anomaly coefficient for even dimensional interface, and the analog of the $g$-function for odd-dimensional interface. These models have a dual description in terms of a gravitational theory in AdS where a bulk scalar field satisfies different boundary conditions on each half of the AdS boundary. We review this construction and show that the results of the large $N$ expansion on the CFT side are in precise agreement with the holographic predictions.