Emergence of pion parton distributions

TL;DR

This paper derives bounds on pion valence-quark distributions using an all-orders evolution scheme and lattice QCD results, leading to parameter-free predictions consistent with QCD expectations.

Contribution

It introduces a novel method to bound pion parton distributions based on an effective charge and lattice QCD data, providing new parameter-free predictions.

Findings

Bounds on Mellin moments of pion DFs derived

Parameter-free predictions for pion DFs obtained

Results consistent with QCD wave function predictions

Abstract

Supposing only that there is an effective charge which defines an evolution scheme for parton distribution functions (DFs) that is all-orders exact, strict lower and upper bounds on all Mellin moments of the valence-quark DFs of pion-like systems are derived. Exploiting contemporary results from numerical simulations of lattice-regularised quantum chromodynamics (QCD) that are consistent with these bounds, parameter-free predictions for pion valence, glue, and sea DFs are obtained. The form of the valence-quark DF at large values of the light-front momentum fraction is consistent with predictions derived using the QCD-prescribed behaviour of the pion wave function.