The structure of quasiparticles in a local Fermi liquid

TL;DR

This paper investigates the dressing of quasiparticles in a local Fermi liquid caused by electron interactions with a dynamic impurity, introducing a new mode-resolved measure and extending Natural Orbital methods for better analysis.

Contribution

It develops a mode-resolved measure of quasiparticle dressing and extends Natural Orbital techniques to analyze excitations in local Fermi liquids.

Findings

Dressing exhibits nontrivial power-law decay at large distances.

Extended Natural Orbital methods successfully characterize quasiparticle excitations.

The approach can be applied to complex geometries like disordered systems or mesoscopic devices.

Abstract

Conduction electrons interacting with a dynamic impurity can give rise to a local Fermi liquid. The latter has the same low energy spectrum as an ideal Fermi gas containing a static impurity. The Fermi liquids's elementary excitations are however not bare electrons. In the vicinity of the impurity, they are dressed by virtual particle-hole pairs. Here we study this dressing. Among other things, we construct a mode-resolved measure of dressing. To evaluate it in position representation, we have to circumvent the limitations of the Numerical Renormalization Group, which discretizes the conduction band logarithmically. We therefore extend Natural Orbital methods, that successfully characterize the ground state, to describe excitations. We demonstrate that the dressing profile shows nontrivial powerlaw decay at large distances. Our Natural Orbital methodology could lay the foundation for calculating the properties of local Fermi liquid quasiparticles in nontrivial geometries such as disordered hosts or mesoscopic devices.