Dynamical vertex mass generation and chiral symmetry breaking on the light-front

TL;DR

This paper demonstrates how dynamical mass generation and chiral symmetry breaking occur on the light-front, challenging the notion that helicity flip amplitudes vanish in the chiral limit, with implications for light-front QCD renormalization.

Contribution

It introduces a model showing how large helicity flip amplitudes are generated dynamically through Fock space summation, elucidating mass generation mechanisms in light-front QCD.

Findings

Helicity flip amplitudes are generated dynamically in the model.

Masses are generated via zero-mode induced counter-terms and small momenta.

Implications for renormalization of light-front Hamiltonians are discussed.

Abstract

Naively, helicity flip amplitudes for fermions seem to vanish in the chiral limit of light-front QCD, which would make it nearly impossible to generate a small pion mass in this framework. Using a simple model, it is illustrated how a large helicity flip amplitude is generated dynamically by summing over an infinite number of Fock space components. While the kinetic mass is basically generated by a zero-mode induced counter-term, the vertex mass is generated dynamically by infinitesimally small, but nonzero, momenta. Implications for the renormalization of light-front Hamiltonians for fermions are discussed.