Photoemission "experiments" on holographic lattices

TL;DR

This paper constructs a holographic lattice model to analyze electron spectral functions, revealing complex peak structures and comparing favorably with Hubbard model results, though some interpretative limitations remain.

Contribution

It introduces a holographic ionic lattice with hyperscaling-violating geometry and studies its electron spectral functions, connecting holography with Hubbard model phenomenology.

Findings

Spectral functions show a three-peak structure with a crossover in the central peak.

Holographic Green functions fit well with Hubbard model Green functions from Monte Carlo.

The model captures incoherent and Hubbard-like features but has limitations in interpretative depth.

Abstract

We construct a 2D holographic ionic lattice with hyperscaling-violating infrared geometry and study single-electron spectral functions ("ARPES photoemission curves") on this background. The spectra typically show a three-peak structure, where the central peak undergoes a crossover from a sharp but not Fermi-liquid-like quasiparticle to a wide incoherent maximum, and the broad side peaks resemble the Hubbard bands. These findings are partially explained by a perturbative near-horizon analysis of the bulk Dirac equation. Comparing the holographic Green functions in imaginary frequency with the Green functions of the Hubbard model obtained from quantum Monte Carlo, we find that the holographic model provides a very good fit to the Hubbard Green function. However, the information loss when transposing the holographic Green functions to imaginary frequencies implies that a deeper connection to Hubbard-like models remains questionable.