Universal fermionic spectral functions from string theory

TL;DR

This paper presents the first holographic calculation of a fermionic response in a strongly coupled 3D system with supergravity duals, revealing universal features like a phonino pole and spectral depletion without a Fermi surface.

Contribution

It provides a universal fermionic spectral function for 3D N=2 SCFTs with supergravity duals, highlighting novel low-frequency behavior and the absence of a Fermi surface.

Findings

Spectral function has a phonino pole.

No Fermi surface observed at finite charge density.

Spectral weight shows power-law depletion at low frequencies.

Abstract

We carry out the first holographic calculation of a fermionic response function for a strongly coupled $d=3$ system with an explicit D=10 or D=11 supergravity dual. By considering the supersymmetry current, we obtain a universal result applicable to all d=3 N=2 SCFTs with such duals. Surprisingly, the spectral function does not exhibit a Fermi surface, despite the fact that the system is at finite charge density. We show that it has a phonino pole and at low frequencies there is a depletion of spectral weight with a power-law scaling which is governed by a locally quantum critical point.