A Precise Determination of (Anti)neutrino Fluxes with (Anti)neutrino-Hydrogen Interactions

We present a novel method to accurately determine the flux of neutrinos and antineutrinos, one of the dominant systematic uncertainty affecting current and future long-baseline neutrino experiments, as well as precision neutrino scattering experiment. Using exclusive topologies in $\nu(\bar \nu)$-hydrogen interactions, $\nu_\mu p \to \mu^- p \pi^+$, $\bar \nu_\mu p \to \mu^+ p \pi^-$, and $\bar \nu_\mu p \to \mu^+ n$ with small hadronic energy, we achieve an overall accuracy on the relative fluxes better than 1\% in the energy range covering most of the available flux. Since we cannot rely on simulations nor model corrections at this level of precision, we present techniques to constrain all relevant systematic uncertainties using data themselves. The method can be implemented using the approach we recently proposed to collect high statistics samples of $\nu(\bar \nu)$-hydrogen interactions in a low-density and high-resolution detector, which could serve as part of the near detector complex in a long-baseline neutrino experiment, as well as a dedicated beam monitoring detector.