• Open Access

Isovector EMC Effect from Global QCD Analysis with MARATHON Data

C. Cocuzza, C. E. Keppel, H. Liu, W. Melnitchouk, A. Metz, N. Sato, and A. W. Thomas (Jefferson Lab Angular Momentum (JAM) Collaboration)
Phys. Rev. Lett. 127, 242001 – Published 6 December 2021

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 He3 to H3 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 on the d/u PDF ratio, they suggest an enhanced nuclear effect on the d-quark PDF in the bound proton, questioning the assumptions commonly made in nuclear PDF analyses.

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  • Received 22 April 2021
  • Revised 23 August 2021
  • Accepted 28 October 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.242001

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Nuclear PhysicsParticles & Fields

Authors & Affiliations

C. Cocuzza1, C. E. Keppel2, H. Liu3, W. Melnitchouk2, A. Metz1, N. Sato2, and A. W. Thomas4 (Jefferson Lab Angular Momentum (JAM) Collaboration)

  • 1Department of Physics, SERC, Temple University, Philadelphia, Pennsylvania 19122, USA
  • 2Jefferson Lab, Newport News, Virginia 23606, USA
  • 3Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
  • 4CSSM and CoEPP, Department of Physics, University of Adelaide South Australia 5005, Australia

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Issue

Vol. 127, Iss. 24 — 10 December 2021

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