Quasiparticle self-energy and many-body effective mass enhancement in a two-dimensional electron liquid

TL;DR

This paper provides a detailed theoretical analysis of quasiparticle self-energy and effective mass in a two-dimensional electron liquid, incorporating recent Monte Carlo data and beyond-RPA effects to match experimental observations.

Contribution

It introduces a comprehensive many-body local fields approach with charge and spin fluctuations beyond RPA, improving the understanding of effective mass in strongly correlated regimes.

Findings

Effective mass enhancement varies with electron density.

Self-consistent Dyson solutions are necessary in strong correlation regimes.

Including charge and spin fluctuations aligns theory with experiments.

Abstract

Motivated by a number of recent experimental studies we have revisited the problem of the microscopic calculation of the quasiparticle self-energy and many-body effective mass enhancement in a two-dimensional electron liquid. Our systematic study is based on the many-body local fields theory and takes advantage of the results of the most recent Diffusion Monte Carlo calculations of the static charge and spin response of the electron liquid. We report extensive calculations of both the real and imaginary parts of the quasiparticle self-energy. We also present results for the many-body effective mass enhancement and the renormalization constant over an extensive range of electron density. In this respect we critically examine the relative merits of the on-shell approximation versus the self-consistent solution of the Dyson equation. We show that in the strongly-correlated regime a solution of the Dyson equation proves necessary in order to obtain a well behaved effective mass. The inclusion of both charge- and spin-density fluctuations beyond the Random Phase Approximation is indeed crucial to get reasonable agreement with recent measurements.