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arXiv · 2506.13616

Global QCD analysis of spin PDFs in the proton with high-$x$ and lattice constraints

C. Cocuzza·N. T. Hunt-Smith·W. Melnitchouk·N. Sato·A. W. Thomas
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Abstract

We perform a comprehensive global QCD analysis of spin-dependent parton distribution functions (PDFs), combining all available data on inclusive and semi-inclusive deep-inelastic scattering (DIS), as well as inclusive weak boson and jet production in polarized $pp$ collisions, simultaneously extracting spin-averaged PDFs and fragmentation functions. Including recent Jefferson Lab DIS data at high $x$, together with subleading power corrections to the leading twist framework, allows us to verify the stability of the PDFs for $W^2 \geq 4$ GeV$^2$ and quantify the uncertainties on the spin structure functions more reliably. We explore the use of new lattice QCD data on gluonic pseudo Ioffe-time distributions, which, together with jet production and high-$x$ DIS data, improve the constraints on the polarized gluon PDF. The expanded kinematic reach afforded by the data into the high-$x$ region allows us to refine the bounds on higher twist contributions to the spin structure functions, and test the validity of the Bjorken sum rule.

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C. Cocuzza, N. T. Hunt-Smith, W. Melnitchouk, N. Sato, A. W. Thomas. 2025-06-16. Global QCD analysis of spin PDFs in the proton with high-$x$ and lattice constraints. https://arxiv.org/abs/2506.13616

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