Strong-Coupling Effects and Single-Particle Properties in an Ultracold Fermi Gas with Mass Imbalance

TL;DR

This paper studies how mass imbalance affects single-particle properties and pseudogap phenomena in strongly interacting ultracold Fermi gases using an extended $T$-matrix theory, revealing differences between light and heavy fermions.

Contribution

It provides the first detailed analysis of mass imbalance effects on single-particle excitations and pseudogap phenomena in strongly interacting Fermi gases.

Findings

Different momentum regions affected by pairing fluctuations for light and heavy fermions.

Distinct pseudogap behaviors observed between the two components.

Pauli blocking effects vary between light and heavy fermions.

Abstract

We investigate single-particle properties of a strongly interacting ultracold Fermi gas with mass imbalance. Using an extended $T$-matrix theory, we calculate the density of states, as well as the single-particle spectral weight, in the unitarity limit above the superfluid phase transition temperature $T_{\rm c}$. We show that the momentum regions where pairing fluctuations strongly affect single-particle excitations are different between light fermions and heavy fermions, reflecting the difference of the Pauli blocking effects between them. In addition, we obtain different pseudogap phenomena associated with pairing fluctuations in between the two components. Since the realization of a mass-imbalanced superfluid Fermi gas is an important challenge in this field, our results would contribute to the understanding of physical properties of the hetero-pairing state.