Cocuzza C, Keppel CE, Liu H, Melnitchouk W, Metz A, Sato N, Thomas AW. Isovector EMC Effect from Global QCD Analysis with MARATHON Data.
PHYSICAL REVIEW LETTERS 2021;
127:242001. [PMID:
34951781 DOI:
10.1103/physrevlett.127.242001]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 08/23/2021] [Accepted: 10/28/2021] [Indexed: 06/14/2023]
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 ^{3}He to ^{3}H 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 F_{2}^{n}/F_{2}^{p} 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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