Constraints on pion parton distributions at small x from leading-neutron electroproduction data

@misc{yang2026constraints,
  title = {{Constraints on pion parton distributions at small $x$ from leading-neutron electroproduction data}},
  author = {C. Yang and P. C. Barry and W. Melnitchouk and N. Sato},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.19415},
  eprint = {2610.19415},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.19415},
}

TY  - UNPB
TI  - Constraints on pion parton distributions at small x from leading-neutron electroproduction data
AU  - C. Yang
AU  - P. C. Barry
AU  - W. Melnitchouk
AU  - N. Sato
PY  - 2026
DA  - 2026/10/14
PB  - arXiv
DO  - 10.48550/arxiv.2610.19415
UR  - https://arxiv.org/abs/2610.19415
AB  - We revisit the extraction of parton distribution functions (PDFs) in the pion in a global QCD analysis of pion--nucleus Drell--Yan and leading-neutron (LN) electroproduction data, in view of recent suggestions that uncertainties on the pion PDFs at small parton momentum fraction x are dramatically underestimated. We perform a set of controlled fits that vary the LN data coverage, PDF parametrization, and positivity constraints, determining both the PDFs and pion-nucleon splitting functions simultaneously. While the use of a restricted H1 LN data sample used by the Fantômas group is found to enlarge the PDF uncertainties and admit solutions with vanishing gluon PDFs, our global analysis provides a good description of an extended H1 and ZEUS LN database, significantly reducing the parametrization dependence and strongly disfavoring a zero gluon distribution.
ER  -