Off-shell effects in bound nucleons and parton distributions from $^1$H, $^2$H, $^3$H and $^3$He data

Understand

We report the results of a new global QCD analysis including deep-inelastic scattering data off $^1$H, $^2$H, $^3$H, and $^3$He targets.

• Nuclear corrections are treated in terms of a nuclear convolution approach with off-shell bound nucleons.
• The off-shell (OS) corrections responsible for the modification of the structure functions (SFs) of bound nucleons are constrained in a global fit along with the proton parton distribution functions (PDFs) and the higher-twist (HT) terms.
• We investigate the proton-neutron difference for the OS correction and discuss our predictions for the SF ratio $F_2^n/F_2^p$ and the corresponding PDF ratio $d/u$ in the proton, as well as their correlations with the underlying treatment of the HT terms and of the OS corrections.