A1 Journal article (refereed)
Global analysis of polarized DIS and SIDIS data with improved small-x helicity evolution (2023)

Adamiak, D., Baldonado, N., Kovchegov, Y. V., Melnitchouk, W., Pitonyak, D., Sato, N., Sievert, M. D., Tarasov, A., & Tawabutr, Y. (2023). Global analysis of polarized DIS and SIDIS data with improved small-x helicity evolution. Physical Review D, 108(11), Article 114007. https://doi.org/10.1103/PhysRevD.108.114007

JYU authors or editors

Publication details

All authors or editors: Adamiak, Daniel; Baldonado, Nicholas; Kovchegov, Yuri V.; Melnitchouk, W.; Pitonyak, Daniel; Sato, Nobuo; Sievert, Matthew D.; Tarasov, Andrey; Tawabutr, Yossathorn

Journal or series: Physical Review D

ISSN: 2470-0010

eISSN: 2470-0029

Publication year: 2023

Publication date: 11/12/2023

Volume: 108

Issue number: 11

Article number: 114007

Publisher: American Physical Society (APS)

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1103/PhysRevD.108.114007

Publication open access: Openly available

Publication channel open access: Partially open access channel

Additional information: Jefferson Lab Angular Momentum (JAM) Collaboration

Abstract

We analyze the world polarized deep-inelastic scattering (DIS) and semi-inclusive DIS (SIDIS) data at low values of x<0.1, using small-x evolution equations for the flavor singlet and nonsinglet helicity parton distribution functions (hPDFs), which resum all powers of both αsln2(1/x) and αsln(1/x)ln(Q2/Q20), with αs being the strong coupling constant. The hPDFs for quarks, antiquarks, and gluons are extracted and evolved to lower values of x to make predictions for the future Electron-Ion Collider (EIC). We improve on our earlier work by employing the more realistic large-Nc&Nf limit of the revised small-x helicity evolution, and by incorporating running coupling corrections along with SIDIS data into the fit. We find an anticorrelation between the signs of the gluon and C-even quark hPDFs, as well as the g1 structure function. While the existing low-x polarized DIS and SIDIS data are insufficient to constrain the initial conditions for the polarized dipole amplitudes in the helicity evolution equations, future EIC data will allow more precise predictions for hPDFs and the g1 structure function for x values beyond those probed at the EIC. Using the obtained hPDFs, we discuss the contributions to the proton spin from quark and gluon spins at small x.

Keywords: scattering (physics); quarks; gluons; particle physics

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Ministry reporting: Yes

Reporting Year: 2024

Preliminary JUFO rating: 2