Photoemission "experiments" on holographic lattices

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.

Nodal-antinodal dichotomy from anisotropic quantum critical continua in holographic models

“…We stress that in our model this difference in the width of the peaks in different directions can not be solely attributed to the broken translational symmetry and corresponding momentum relaxation, which would indeed broaden the quasiparticle resonance in the x direction, as was shown in refs. [32][33][34][35][36][37]. As our general analysis in section 2 shows, the Green's functions in the two directions behave qualitatively differently due to the anisotropic features of deep IR geometry.…”

“…These features are absent when the explicit symmetry breaking is irrelevant in IR as in refs. [32][33][34][35][36][37]. In particular, for IR-irrelevant deformations the width of the peaks in both directions would become smaller as the temperature is lowered, causing the nodal-antinodal dichotomy effect to disappear at small temperatures.…”