We discuss results from our global QCD analyses including nuclear data off
deuterium from various measurements, as well as off 3H and 3He targets
from the MARATHON experiment. We simultaneously determine the parton
distribution functions of the proton, the higher-twist terms, and the nucleon
off-shell correction functions responsible for the modifications of the
partonic structure in bound protons and neutrons. In particular, we study the
neutron-proton asymmetry of the off-shell correction and its interplay with the
treatment of the higher-twist terms. We observe that the data on the
3He/3H cross section ratio are consistent with a single isoscalar
off-shell function. We also provide our predictions on the ratio F2nβ/F2pβ
and on the d and u quark distributions in the proton and in the 3H and
3He nuclei.Comment: 6 pages, 4 figures. Presented at DIS2023: XXX International Workshop
on Deep-Inelastic Scattering and Related Subjects, Michigan State University,
USA, 27-31 March 202