On the Electromagnetic Response of Charged Bosons Coupled to a Chern-Simons Gauge Field: A Path Integral Approach

TL;DR

This paper investigates the electromagnetic response of charged bosons coupled to a Chern-Simons gauge field using path integral methods, revealing exact quantization of transverse conductivity and analyzing edge states and density fluctuations.

Contribution

It introduces a path integral framework to derive an effective action for charged bosons with Chern-Simons coupling, highlighting exact conductivity quantization and edge state relevance.

Findings

Quantization of transverse conductivity is exact with homogeneous magnetic fields.

Edge states play a significant role in the system's electromagnetic response.

Density fluctuation propagator and effective action with vortex excitations are derived.

Abstract

We analyze the electromagnetic response of a system of charged bosons coupled to a Chern-Simons gauge field. Path integral techniques are used to obtain an effective action for the particle density of the system dressed with quantum fluctuations of the CS gauge field. From the action thus obtained we compute the U(1) current of the theory for an arbitrary electromagnetic external field. For the particular case of a homogeneous external magnetic field, we show that the quantization of the transverse conductivity is exact, even in the presence of an arbitrary impurity distribution. The relevance of edge states in this context is analyzed. The propagator of density fluctuations is computed, and an effective action for the matter density in the presence of a vortex excitation is suggested.