Quantum critical point of Dirac fermion mass generation without spontaneous symmetry breaking

TL;DR

This paper investigates a lattice model of interacting Dirac fermions in 2+1 dimensions, revealing a continuous quantum phase transition to a gapped phase without spontaneous symmetry breaking, challenging traditional mass generation mechanisms.

Contribution

It demonstrates a novel mass generation mechanism in Dirac fermions that does not involve spontaneous symmetry breaking, aligning with recent topological insulator and lattice QCD studies.

Findings

Identifies a continuous quantum phase transition without symmetry breaking.

Shows mass generation without Dirac fermion bilinear condensation.

Connects results to topological insulators and lattice QCD research.

Abstract

We study a lattice model of interacting Dirac fermions in $(2+1)$ dimension space-time with an SU(4) symmetry. While increasing interaction strength, this model undergoes a {\it continuous} quantum phase transition from the weakly interacting Dirac semimetal to a fully gapped and nondegenerate phase without condensing any Dirac fermion bilinear mass operator. This unusual mechanism for mass generation is consistent with recent studies of interacting topological insulators/superconductors, and also consistent with recent progresses in lattice QCD community.