Uncertainties on the ${\nu }_{\mu }$/${\nu }_e$, ${\bar{\nu }}_{\mu }$/${\bar{\nu }}_e$ and ${\nu }_e$/${\bar{\nu }}_e$ cross-section ratio from the modelling of nuclear effects and their impact on neutrino oscillation experiments

The potential for mis-modeling of ${\nu }_{\mu }$/${\nu }_e$, ${\bar{\nu }}_{\mu }$/${\bar{\nu }}_e$ and ${\nu }_e$/${\bar{\nu }}_e$ cross section ratios due to nuclear effects is quantified by considering model spread within the full kinematic phase space for CCQE interactions. Its impact is then propagated to simulated experimental configurations based on the Hyper-K and ESS$\nu$SB experiments. Although significant discrepancies between theoretical models is confirmed, it is found that these largely lie in regions of phase space that contribute only a very small portion of the flux integrated cross sections. Overall, a systematic uncertainty on the oscillated flux-averaged ${\nu }_e$/${\bar{\nu }}_e$ cross-section ratio is found to be $\sim$2% and $\sim$4% for Hyper-K and ESS$\nu$SB respectively.