Fermi Edge Singularities: Boundstates and Finite Size Effects

TL;DR

This paper investigates Fermi edge singularities using conformal field theory, sum rules, and numerical models, revealing universal behaviors and the impact of bound states and finite size effects on adsorption intensity.

Contribution

It establishes a general relationship between FES and Anderson orthogonality exponent, including bound state cases, and provides universal finite size predictions.

Findings

Universal adsorption intensity results for finite samples

Numerical validation of theoretical predictions

Evolution of adsorption intensity with electron density

Abstract

Fermi edge adsorption singularities (FES) are studied using a combination of conformal field theory (CFT), an exact sum rule and numerical work on a tight binding model which is shown to exhibit remarkable simplifying features. The relationship between FES and Anderson orthogonality exponent is established in great generality, using CFT, including the case where the core hole potential produces a boundstate. Universal results on the adsorption intensity in a finite sized sample are obtained. Various predictions are checked numerically and the evolution of the adsorption intensity with electron density is studied.