3+1 dimensional topological field theory as the effective action of neutral fermions

TL;DR

This paper develops a 3+1 dimensional topological field theory for neutral fermions interacting with electromagnetic fields, useful for describing time reversal invariant topological insulators.

Contribution

It introduces a novel effective action framework for neutral fermions derived from integrating out fermionic fields, applicable to topological insulators.

Findings

Provides a new effective action formulation for topological insulators.

Connects neutral quasiparticles to collective behaviors of particles and holes.

Offers a general approach for modeling topological phases in 3+1 dimensions.

Abstract

We proposed an action of neutral fermions interacting with external electromagnetic fields to construct a 3+1 dimensional topological field theory as the effective action attained by integrating out the fermionic fields in the related path integral. These neutral quasiparticles are assumed to emerge from the collective behavior of the original physical particles and holes (antiparticles). Although our construction is general it is particularly useful to formulate effective actions of the time reversal invariant topological insulators.