The Fermi-polaron in two dimensions: Importance of the two-body bound state

TL;DR

This paper analyzes the Fermi-polaron problem in two dimensions, emphasizing the significance of the two-body bound state for accurately determining the impurity's energy and effective mass.

Contribution

It provides analytical expressions for polaron properties in 2D, incorporating the two-body bound state, and extends the approach to 1D and 3D with good agreement to known results.

Findings

Analytical formulas for polaron energy and mass in 2D.

Inclusion of the two-body bound state is crucial for strong interactions.

Good agreement with previous results in 1D and 3D.

Abstract

We investigate a single impurity interacting with a free two-dimensional atomic Fermi gas. The interaction between the impurity and the gas is characterized by an arbitrary attractive short-range potential, which, in two dimensions, always admits a two-particle bound state. We provide analytical expressions for the energy and the effective mass of the dressed impurity by including the two-body bound state, which is crucial for strong interactions, in the integral equation for the effective interaction. Using the same method we give also the results for the polaron parameters in one and three dimensions finding a pretty good agreement with previous known results. Thus our relations can be used as a simple way to estimate the polaron parameters once the two-body bound state of the interaction potential is known.