Improved constraint on the MINERvA medium energy neutrino flux using $\bar{\nu}e^{-} \!\rightarrow \bar{\nu}e^{-}$ data

Processes with precisely known cross sections, like neutrino electron elastic scattering ($\nu e^{-} \!\rightarrow \nu e^{-}$) and inverse muon decay ($\nu_\mu e^{-} \!\rightarrow \mu^{-} \nu_e$) have been used by MINERvA to constrain the uncertainty on the NuMI neutrino beam flux. This work presents a new measurement of neutrino elastic scattering with electrons using the medium energy \numubar enhanced NuMI beam. A sample of 578 events after background subtraction is used in combination with the previous measurement on the \numu beam and the inverse muon decay measurement to reduce the uncertainty on the \numu flux in the \numu-enhanced beam from 7.6\% to 3.3\% and the \numubar flux in the \numubar-enhanced beam from 7.8\% to 4.7\%.