Pion PDFs confronted by Fixed-Target Charmonium Production

TL;DR

This paper reviews recent advances in understanding the pion's internal quark structure through global PDF analysis and demonstrates how charmonium production data can constrain pion PDFs.

Contribution

It introduces new global analysis methods for pion PDFs and shows how charmonium production data can improve these distributions.

Findings

Charmonium production data can constrain pion PDFs.

Comparison of data with CEM and NRQCD models supports their use.

Recent global analyses incorporate diverse experimental data.

Abstract

The pion, as the Goldstone boson of the strong interaction, is the lightest QCD bound state and responsible for the long-range nucleon-nucleon interaction inside the nucleus. Our knowledge on the pion partonic structure is limited by the existing Drell-Yan data which are primarily sensitive to the pion valence-quark distributions. The recent progress of global analysis of pion's parton distribution functions (PDFs) utilizing various experimental approaches are introduced. From comparisons between the pion-induced $J/\psi$ and $\psi(2S)$ production data with theoretical calculations using the CEM and NRQCD models, we show how these charmonium production data could provide useful constraints on the pion PDFs.