Holographic Spectral Functions in Metallic AdS/CFT

TL;DR

This paper investigates the effects of a finite electric field on holographic spectral functions in a D3/D7 setup, revealing a crossover behavior in conductivity and photoproduction related to probe brane embeddings.

Contribution

It extends previous holographic analyses by incorporating finite electric fields and studying their impact on spectral functions and conductivity in the D3/D7 model.

Findings

Identification of a singular shell region in the D7-brane geometry.

Consistency with known electrical conductivity expressions.

Observation of rapid changes in conductivity and photoproduction due to parameter variations.

Abstract

We study the holographic D3/D7 setup dual to N=4 supersymmetric Yang-Mills with quenched fundamental matter. We extend the previous analyses of conductivity and photoproduction to the case where there is a finite electric field. Due to the electric field a special region in the D7-brane geometry, labelled the singular shell, appears generically, and the computation of correlators involves a careful study of the indicial exponents both at this singular region and at the horizon. We show that there is a unique choice consistent with the known expression for the electrical conductivity found by Karch and O'Bannon. We explore the parameter space spanned by the quark mass, the baryon density and the electric field. We find a region where the conductivity and photoproduction change rapidly and trace this behavior to competing effects which manifest themselves as a crossover behavior in the probe brane embeddings.