Flavor dependence of the nucleon valence structure from nuclear deep inelastic scattering data.

The partonic structure of the nucleon in the valence region is studied using a global analysis of nuclear deep inelastic scattering (DIS) data on the proton and on nuclei from $A = 2$ (deuterium) to 208 (lead) to account for the modification of the structure function of nucleons bound in atomic nuclei (i.e. the EMC effect). As compared to previous analyses that only use proton and deuterium data, we find a larger valence down-quark contribution at high-$x_B$. The neutron-to-proton structure function ratio $F_2^n/F_2^p$ is extracted for $x_B = 0.2 - 0.9$, with an $x_B \rightarrow 1$ limit of $0.47 \pm 0.04$, in agreement with predictions such as those of perturbative QCD and Dyson Schwinger equation expectations, but in disagreement with predictions such as the scalar di-quark dominance model. Predictions are also made for $F_2^{^3\mathrm{He}}/F_2^{^3\mathrm{H}}$, recently measured by the MARATHON collaboration, the nuclear correction function that is needed to extract $F_2^n/F_2^p$ from $F_2^{^3\mathrm{He}}/F_2^{^3\mathrm{H}}$, and the systematic uncertainty associated with this extraction.