Attractive polaron in a Dirac system within the ladder approximation

TL;DR

This paper studies the properties of attractive polarons in Dirac systems at zero temperature using a non-self-consistent T-matrix approach, highlighting the effects of chiral factors and finite temperature.

Contribution

It introduces a variational ansatz for the pair propagator and self-energy in Dirac systems, focusing on a non-self-consistent T-matrix that considers only the bare channel.

Findings

Pair propagator fluctuation is proportional to cos a.

Derived expressions for pair propagator, self-energy, and T-matrix.

Analyzed the particle spectral function at finite temperature.

Abstract

We investigate the properties of the attractive polaron formed by a single impurity dressed with the particle-hole excitations in a Dirac system at zero-temperature limit. Base on the single particle-hole variational ansatz, we deduce the expressions of the pair propagator, self-energy (negative), and the non-self-consistent medium $T$-matrix. Different to the self-consistent $T$-matrix which contains two channels due to the many-body effect, the non-self-consistent $T$-matrix discussed in this paper contains only the closed channel (i.e., the bare one) since we consider only a finite number of the majority particles. The chiral factor is also discussed within the pair propagator due to the scattering feature of the Dirac system (with a certain scattering angle $a$), and we found that the fluctuation of the pair propagator is proportional to the term ${\rm cos}\ a$. Finally, we also discuss the particle spectral function of the polaron in the presence of quantum many-body effect as well as the pair-propagator at finite temperature.