Single-particle spectral functions in the normal phase of a strongly-attractive Bose-Fermi mixture

TL;DR

This paper investigates the single-particle spectral functions in a strongly-attractive Bose-Fermi mixture without boson condensation, revealing unconventional particle-hole excitations that could be experimentally observed.

Contribution

It provides a detailed analysis of spectral functions and dispersions in a Bose-Fermi mixture across different attraction regimes using a T-matrix approach, including effects of imbalance.

Findings

Discovery of particle-hole excitations mixing two Fermi surfaces

Spectral functions vary significantly with attraction strength

Potential for experimental observation via radio-frequency spectroscopy

Abstract

We calculate the single-particle spectral functions and quasi-particle dispersions for a Bose-Fermi mixture when the boson-fermion attraction is sufficiently strong to suppress completely the condensation of bosons at zero temperature. Within a T-matrix diagrammatic approach, we vary the boson-fermion attraction from the critical value where the boson condensate first disappears to the strongly attractive (molecular) regime and study the effect of both mass- and density-imbalance on the spectral weights and dispersions. An interesting spectrum of particle-hole excitations mixing two different Fermi surfaces is found. These unconventional excitations could be produced and explored experimentally with radio-frequency spectroscopy.