Transport across interfaces in symmetric orbifolds

TL;DR

This paper investigates how conformal boundaries encode energy transport in symmetric orbifold theories, comparing weak coupling calculations at the orbifold point with strong coupling holographic results, revealing significant coupling-dependent changes.

Contribution

It provides the first comparison of transport coefficients at the orbifold point and in the strongly coupled holographic regime for symmetric orbifold theories.

Findings

Transport coefficients at the orbifold point are averages of seed theory coefficients.

Holographic transmission coefficients increase with coupling, contrasting boundary entropy behavior.

The study offers insights into twisted-sector data and boundary states in these theories.

Abstract

We examine how conformal boundaries encode energy transport coefficients -- namely transmission and reflection probabilities -- of corresponding conformal interfaces in symmetric orbifold theories. These constitute a large class of irrational theories and are closely related to holographic setups. Our central goal is to compare such coefficients at the orbifold point (a field theory calculation) against their values when the orbifold is highly deformed (a gravity calculation) -- an approach akin to past AdS/CFT-guided comparisons of physical quantities at strong versus weak coupling. At the orbifold point, we find that the (weighted-average) transport coefficients are simply averages of coefficients in the underlying seed theory. We then focus on the symmetric orbifold of the $\mathbb{T}^4$ sigma model interface CFT dual to type IIB supergravity on the 3d Janus solution. We compare the holographic transmission coefficient, which was found by [1], to that of the orbifold point. We find that the profile of the transmission coefficient substantially increases with the coupling, in contrast to boundary entropy. We also present some related ideas about twisted-sector data encoded by boundary states.