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arXiv · 1804.01965

First Monte Carlo global QCD analysis of pion parton distributions

P. C. Barry·N. Sato·W. Melnitchouk·Chueng-Ryong Ji
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Abstract

We perform the first global QCD analysis of parton distribution functions (PDFs) in the pion, combining $πA$ Drell-Yan 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, $\sim 30\%$, than that inferred from Drell-Yan data alone, with sea quarks carrying a somewhat smaller fraction, $\sim 15\%$, at the input scale. Within the same effective theory framework, the chiral splitting function and pion PDFs can be used to describe the $\bar d-\bar u$ asymmetry in the proton.

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P. C. Barry, N. Sato, W. Melnitchouk, Chueng-Ryong Ji. 2018-08-20. First Monte Carlo global QCD analysis of pion parton distributions. https://doi.org/10.1103/physrevlett.121.152001

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