Gapped Fermions in Top-down Holographic Superconductors

TL;DR

This paper uses holography to analyze fermionic spectral functions in three zero-temperature states of ABJM theory, revealing gapped spectra due to charge and interaction effects.

Contribution

It provides the first holographic computation of fermionic spectral functions in these specific finite-density, zero-temperature states with broken U(1) symmetry.

Findings

Fermionic operators exhibit gapped spectra in all three states.

The gap arises from small fermion charge in one case.

In other cases, the gap results from particle-hole mixing interactions.

Abstract

We use holography to compute spectral functions of certain fermionic operators in three different finite-density, zero-temperature states of ABJM theory with a broken U(1) symmetry. In each of the three states, dual to previously studied domain wall solutions of four-dimensional gauged supergravity, we find that the fermionic operators have gapped spectra. In one case the gap can be traced to the small charge of the fermions, while in the other cases it is due to a particular interaction that mixes particles and holes.