Pionic Parton Distributions Revisited

TL;DR

This paper revisits pion parton distributions using a constituent quark model constrained by experimental data, providing parameter-free predictions for gluon and sea-quark content that are relevant for photon structure studies.

Contribution

It introduces a novel, parameter-free method to calculate pion parton distributions based on nucleon data and constituent quark model constraints.

Findings

Unique small-x predictions for pion gluon and sea-quark distributions.

Analytic parametrizations of pion parton distributions at LO and NLO.

Results are relevant for photon structure function modeling.

Abstract

Using constituent quark model constraints we calculate the gluon and sea-quark content of pions solely in terms of their valence density (fixed by \pi N Drell-Yan data) and the known sea and gluon distributions of the nucleon, using the most recent updated valence-like input parton densities of the nucleon. The resulting small-x dynamical QCD predictions for g^{\pi}(x,Q^2) and \bar{q}^{\pi}(x,Q^2) are unique and parameter free. Simple analytic parametrizations of the resulting parton distributions of the pion are presented in LO and NLO. These results and parametrizations will be important, among other things, for updated formulations of the parton distributions of real and virtual photons.