Transport Properties of Holographic Defects

TL;DR

This paper investigates the charge transport characteristics of a defect in a strongly coupled gauge theory using holographic duality, revealing universal behavior and the influence of higher derivative corrections.

Contribution

It provides a detailed holographic analysis of defect charge transport, highlighting the universality between different brane configurations and the effects of finite coupling corrections.

Findings

Transport properties are nearly identical for D5 and D7 branes.

A conduction threshold depends on the wave-number of perturbations.

Finite coupling effects modify transport via higher derivative interactions.

Abstract

We study the charge transport properties of fields confined to a (2+1)-dimensional defect coupled to (3+1)-dimensional super-Yang-Mills at large-$\nc$ and strong coupling, using AdS/CFT techniques applied to linear response theory. The dual system is described by $\nf$ probe D5- or D7-branes in the gravitational background of $\nc$ black D3-branes. Surprisingly, the transport properties of both defect CFT's are essentially identical -- even though the D7-brane construction breaks all supersymmetries. We find that the system possesses a conduction threshold given by the wave-number of the perturbation and that the charge transport arises from a quasiparticle spectrum which is consistent with an intuitive picture where the defect acquires a finite width. We also examine finite-$\lambda$ modifications arising from higher derivative interactions in the probe brane action.