On the Interplay of Nuclear and Higher-Twist Corrections in Nuclear Structure Functions

We discuss results from our global QCD analyses including nuclear data off deuterium from various measurements, as well as off $\htri$ and $\hetri$ targets from the \mara{} 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 $\hetri/\htri, \hetri/\hdeu$, and $\htri/\hdeu$ cross section ratio are in good agreement with the predictions based on a single isoscalar off-shell function. We provide the corresponding predictions on the ratio $F_2^n/F_2^p$, on the $d$ and $u$ quark distributions in the proton and in the $\htri$ and $\hetri$ nuclei, as well as for future measurements of the EMC effect with parity-violating Deep Inelastic Scattering (DIS).