Drawing insights from pion parton distributions

Abstract

A symmetry-preserving continuum approach to the two valence-body bound-state problem is used to calculate the valence, glue and sea distributions within the pion; unifying them with, inter alia, electromagnetic pion elastic and transition form factors. The analysis reveals the following momentum fractions at the scale ${\zeta }_2:=2$GeV: $⟨x_{\mathrm{valence}}⟩=0.48(3)$, $⟨x_{\mathrm{glue}}⟩=0.41(2)$, $⟨x_{\mathrm{sea}}⟩=0.11(2)$; and despite hardening induced by the emergent phenomenon of dynamical chiral symmetry breaking, the valence-quark distribution function, $q^{\pi }(x)$, exhibits the $x\simeq 1$ behaviour predicted by quantum chromodynamics (QCD). After evolution to $\zeta =5.2$GeV, the prediction for $q^{\pi }(x)$ matches that obtained using lattice-regularised QCD. This confluence should both stimulate improved analyses of existing data and aid in planning efforts to obtain new data on the pion distribution functions.

Comments: 6 pages, 1 figure. To be published as a Letter in Chinese Physics C. arXiv admin note: substantial text overlap with arXiv:1905.05208