First evidence for isovector EMC effect from global QCD analysis with MARATHON data

ORAL

Abstract

We report the results of a Monte Carlo global QCD analysis of unpolarized parton distribution functions (PDFs), including for the first time constraints from ratios of 3He to 3H structure functions recently obtained by the MARATHON experiment at Jefferson Lab. Our simultaneous analysis of nucleon PDFs and nuclear effects in A=2 and A=3 nuclei reveals the first indication for an isovector nuclear EMC effect in light nuclei. We find that while the MARATHON data yield relatively weak constraints on the F2n/F2p neutron to proton structure function ratio and the d/u PDF ratio, they suggest a strongly enhanced nuclear effect on the d-quark PDF in the bound proton.

*This work was supported by the U.S. Department of Energy Contract No. DE-AC05-06OR23177, under which Jefferson Science Associates, LLC operates Jefferson Lab, and the National Science Foundation under grant number PHY-1516088. The work of C.C. and A.M. was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, within the framework of the TMD Topical Collaboration, and by Temple University (C.C.). The work of A.W.T. was supported by the University of Adelaide and by the Australian Research Council through the Discovery Project DP180100497. The work of N.S. was supported by the DOE, Office of Science, Office of Nuclear Physics in the Early Career Program.

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Publication: arXiv:2104.06946

Presenters

  • Wally Melnitchouk

    • Jefferson Lab

Authors

  • Wally Melnitchouk

    • Jefferson Lab

  • Christopher Cocuzza

    • Temple University

  • Cynthia E Keppel

    • Jefferson Lab
    • Thomas Jefferson National Accelerator Facility

  • Hanjie Liu

    • University of Massachusetts Amherst

  • Andreas Metz

    • Temple University

  • Nobuo Sato

    • Jefferson Lab
    • Jefferson Lab/Jefferson Science Associat

  • Anthony W Thomas AC

    • Univ of Adelaide