  By taking advantage of symmetries with respect to the plane containing the directions of the neutrino and outgoing lepton, it is possible to isolate neutrino interactions on hydrogen in composite nuclear targets. This technique enables us to study the `primary' neutrino-nucleon interaction and therefore gain access to fundamental model parameters free from nuclear effects. Using T2K Monte Carlo equivalent to $\sim7\times10^{21}$ POT, we present an update on the measurement of the exclusive charged-current $\mu^-$, p, $\pi^+$ final state on hydrogen. 
Measuring neutrino-induced exclusive charge-current final states on   hydrogen at T2K