Polaron in dilute 2D Bose gas at low temperatures

TL;DR

This paper investigates the properties of a Bose polaron in a dilute two-dimensional Bose gas at finite temperatures, focusing on energy, effective mass, and quasiparticle behavior, revealing temperature-dependent spectral features.

Contribution

It provides a perturbative analysis of the polaron's spectral properties in 2D at finite temperatures, highlighting the temperature effects on quasiparticle residue and Green's function structure.

Findings

Polaron energy and effective mass are well-defined across all temperatures.

Quasiparticle residue diverges logarithmically at finite temperatures.

Pole structure of the Green's function is only visible at zero temperature.

Abstract

The properties of a Bose polaron immersed in a dilute two-dimensional medium at finite temperatures are discussed. Assuming that the impurity is weakly-coupled to the bath particles we have perturbatively calculated the polaron energy, effective mass, quasiparticle residue and damping rate. The parameters of impurity spectrum are found to be well-defined in the whole temperature region whereas the pole structure of the impurity Green's function is visible only at absolute zero. At any finite temperatures the quasiparticle residue is logarithmically divergent signalling of the branch-cut behavior of the polaron propagator.