Quasiparticle lifetime in ultracold fermionic mixtures with density and mass imbalance

TL;DR

This paper explores diverse quasiparticle decay behaviors in ultracold fermionic mixtures with density and mass imbalance, revealing novel scaling laws and regimes that resemble those in various physical systems, with potential experimental detection.

Contribution

It uncovers new scaling laws for quasiparticle decay rates in imbalanced Fermi mixtures, extending understanding beyond conventional Fermi liquid theory.

Findings

Decay rate can be linear or exhibit a plateau depending on parameters.

Plateau extends from degenerate to classical regimes of the light species.

Results are derived in the weakly interacting limit, ensuring quantitative reliability.

Abstract

We show that atomic Fermi mixtures with density and mass imbalance exhibit a rich diversity of scaling laws for the quasiparticle decay rate beyond the quadratic energy and temperature dependence of conventional Fermi liquids. For certain densities and mass ratios, the decay rate is linear whereas in other cases it exhibits a plateau. Remarkably, this plateau extends from the deeply degenerate to the high temperature classical regime of the light species. Many of these scaling laws are analogous to what is found in very different systems including dirty metals, liquid metals, and high temperature plasmas. The Fermi mixtures can in this sense span a whole range of seemingly diverse and separate physical systems. Our results are derived in the weakly interacting limit making them quantitatively reliable. The different regimes can be detected with radio-frequency spectroscopy.