Soft-Gluon Resummation and the Valence Parton Distribution Function of the Pion

TL;DR

This paper refines the valence pion parton distribution function by incorporating next-to-leading-logarithmic threshold resummation effects in Drell-Yan data analysis, resulting in a softer high-x distribution consistent with QCD predictions.

Contribution

It introduces a new analysis of Drell-Yan data including threshold resummation effects, providing a more accurate valence pion PDF at high momentum fractions.

Findings

Valence distribution is softer at high x than previous NLO analyses.

Results align with perturbative-QCD counting rules.

Findings are consistent with Dyson-Schwinger equation predictions.

Abstract

We determine the valence parton distribution function of the pion by performing a new analysis of data for the Drell-Yan process $\pi^- N\to \mu^+\mu^-X$. Compared to previous analyses, we include next-to-leading-logarithmic threshold resummation effects in the calculation of the Drell-Yan cross section. As a result of these, we find a considerably softer valence distribution at high momentum fractions $x$ than obtained in previous next-to-leading order analyses, in line with expectations based on perturbative-QCD counting rules or Dyson-Schwinger equations.