Imaging dynamical chiral symmetry breaking: pion wave function on the light front

TL;DR

This paper projects the pion's Bethe-Salpeter wave-function onto the light-front using QCD Dyson-Schwinger equations, revealing how dynamical chiral symmetry breaking influences the pion's internal structure.

Contribution

It provides a novel light-front projection of the pion wave-function derived from Dyson-Schwinger equations, highlighting the impact of chiral symmetry breaking on the distribution amplitude.

Findings

Computed pion wave-functions are broader than the asymptotic form.

Dynamical chiral symmetry breaking causes the hardening of the amplitude.

Results are consistent across different kernel approximations.

Abstract

We project onto the light-front the pion's Poincare'-covariant Bethe-Salpeter wave-function, obtained using two different approximations to the kernels of QCD's Dyson-Schwinger equations. At an hadronic scale both computed results are concave and significantly broader than the asymptotic distribution amplitude, \phi_\pi^{asy}(x)=6 x(1-x); e.g., the integral of \phi_\pi(x)/\phi_\pi^{asy}(x) is 1.8 using the simplest kernel and 1.5 with the more sophisticated kernel. Independent of the kernels, the emergent phenomenon of dynamical chiral symmetry breaking is responsible for hardening the amplitude.