Probing Free Nucleons with (Anti)neutrinos

We discuss a method to study free protons and neutrons using $\nu(\bar \nu)$-hydrogen (H) Charged Current (CC) inelastic interactions, together with various precision tests of the isospin (charge) symmetry using $\nu$ and $\bar \nu$ CC interactions on both H and nuclear targets. Probing free nucleons with (anti)neutrinos provides information about their partonic structure, as well as a crucial input for the modeling of $\nu(\bar\nu)$-nucleus (A) interactions. Such measurements can also represent a tool to address some of the limitations of accelerator-based neutrino scattering experiments on nuclear targets, originating from the combined effect of the unknown (anti)neutrino energy and of the nuclear smearing. We also discuss a method to impose constraints on nuclear effects and calibrate the (anti)neutrino energy scale in $\nu(\bar \nu)$-A interactions, which are two outstanding systematic uncertainties affecting present and future long-baseline neutrino experiments.