Are Pions Perturbative in Effective Field Theory?

TL;DR

This paper investigates the conditions under which pions can be treated perturbatively within effective field theory, concluding that such treatment is only valid at energies well below the pion mass, making explicit inclusion unnecessary at low energies.

Contribution

It demonstrates the limitations of perturbative inclusion of pions in effective field theory, emphasizing the energy scale constraints for validity.

Findings

Perturbative treatment of pions is valid only at energies below the pion mass.

Explicit inclusion of pions is unnecessary at low energies.

Perturbative approach is limited to external momenta well below the pion mass.

Abstract

It is shown that pions can be included perturbatively into effective field theory only for the external momenta, well below the pion mass. But for such low energies it is not necessary to include pions explicitly.