Fermi edge singularities in X-ray spectra of strongly correlated fermions

TL;DR

This paper investigates how Fermi edge singularities manifest in X-ray spectra of strongly correlated fermions, revealing that such features can persist even in systems with vanishing density of states at the Fermi level, using bosonization techniques.

Contribution

It demonstrates the persistence and modification of Fermi edge singularities in strongly correlated fermion systems with vanishing density of states, employing bosonization.

Findings

Fermi edge singularities can exist even with zero density of states at the Fermi energy.

The relationship between singularities and the density of states is complex and subtle.

Bosonization effectively captures the effects of interactions on X-ray spectra.

Abstract

We discuss the problem of the X-ray absorption in a system of interacting fermions and, in particular, those features in the X-ray spectra that can be used to discriminate between conventional Fermi-liquids and novel "strange metals". Focusing on the case of purely forward scattering off the core-hole potential, we account for the relevant interactions in the conduction band by means of the bosonization technique. We find that the X-ray Fermi edge singularities can still be present, although modified, even if the density of states vanishes at the Fermi energy, and that, in general, the relationship between the two appears to be quite subtle.