Landau-Fermi liquids without quasiparticles

TL;DR

This paper demonstrates that Landau-Fermi liquid theory can be microscopically justified even without quasiparticles, challenging the traditional belief that quasiparticles are essential for Fermi liquid behavior.

Contribution

It provides a microscopic framework for Landau-Fermi liquids in systems lacking quasiparticles, expanding the theory's applicability.

Findings

Fermi liquid behavior can occur without quasiparticles.

The interacting density of states can vanish at the chemical potential.

A pole singularity in the self-energy can still support Fermi liquid properties.

Abstract

Landau-Fermi liquid theory is conventionally believed to hold whenever the interacting single-particle density of states develops a $\delta$-like component at the Fermi surface, which is associated with quasiparticles. Here we show that a microscopic justification can be actually achieved under more general circumstances, even in case coherent quasiparticles are totally missing and the interacting single-particle density of states vanishes at the chemical potential as consequence of a pole singularity in the self-energy.