First Monte Carlo Global QCD Analysis of Pion Parton Distributions
Abstract
We perform the first global QCD analysis of parton distribution functions (PDFs) in the pion, combining π A DrellYan data with leading neutron electroproduction from HERA within a Monte Carlo approach based on nested sampling. Inclusion of the HERA data allows the pion PDFs to be determined down to much lower values of x , with relatively weak model dependence from uncertainties in the chiral splitting function. The combined analysis reveals that gluons carry a significantly higher pion momentum fraction, ∼30 % , than that inferred from DrellYan data alone, with sea quarks carrying a somewhat smaller fraction, ∼15 %, at the input scale. Within the same effective theory framework, the chiral splitting function and pion PDFs can be used to describe the d ¯u ¯ asymmetry in the proton.
 Publication:

Physical Review Letters
 Pub Date:
 October 2018
 DOI:
 10.1103/PhysRevLett.121.152001
 arXiv:
 arXiv:1804.01965
 Bibcode:
 2018PhRvL.121o2001B
 Keywords:

 High Energy Physics  Phenomenology;
 High Energy Physics  Experiment;
 Nuclear Theory
 EPrint:
 This article will appear in Physical Review Letters