Massless fermions in multi-flavor QED_2

TL;DR

This paper analyzes the phase structure of multi-flavor QED_2 at finite baryon density, revealing two distinct screening phases and performing renormalization to establish massless conditions in both zero and finite density cases.

Contribution

It provides a detailed analysis of the ground state and phase transitions in multi-flavor QED_2 with finite density, including renormalization procedures for massless fermions.

Findings

Identification of two phases: full screening at low density and partial screening at high density.

Renormalization of the bosonized model confirms massless fermions in both density regimes.

Explicit characterization of the ground state under finite baryon density.

Abstract

The ground state of the multi-flavor 2-dimensional quantum electrodynamics (QED_2) is determined in the presence of finite baryon density, and it is shown that the model possesses two phases, the low density phase where the external baryon density is totally screened, and the high density phase, where the screening is only partial. The renormalization of the bosonized version of the model is also performed for both the zero and the finite density model giving massless multi-flavor QED_2 in both cases.