English

Isospin dependence of nuclear EMC effect from global QCD analysis

High Energy Physics - Phenomenology 2026-02-23 v1 High Energy Physics - Experiment Nuclear Theory

Abstract

We perform a new global QCD analysis of unpolarized parton distribution functions (PDFs) in the nucleon from proton, deuteron and A=3A=3 data, including recent measurements of 3^3He/DD and 3^3H/DD cross section ratios from the MARATHON experiment at Jefferson Lab. Simultaneously inferring the PDFs and nucleon off-shell corrections allows both to be determined consistently, without theoretical assumptions about the isospin dependence of nuclear effects. The analysis provides strong evidence for the need of nucleon off-shell corrections to describe the A=3A=3 data, and suggests the presence of both isoscalar and isovector nuclear effects in A3A \leq 3 nuclei. We find that the extracted EMC ratios of nuclear to nucleon structure functions for A=2A=2 and 3 differ from those naively extrapolated from heavy nuclei down to low AA.

Keywords

Cite

@article{arxiv.2602.16589,
  title  = {Isospin dependence of nuclear EMC effect from global QCD analysis},
  author = {C. Cocuzza and T. J. Hague and W. Melnitchouk and N. Sato and A. W. Thomas},
  journal= {arXiv preprint arXiv:2602.16589},
  year   = {2026}
}

Comments

32 pages, 10 figures