Measurement of the ${\bar{\nu }}_{\mu }-$Hydrogen Charged-Current Quasi-Elastic Cross Section using the NOvA Near Detector

Abstract

We report a measurement of the total cross section for muon antineutrino charged-current quasi-elastic scattering on hydrogen, ${\bar{\nu }}_{\mu }\mathrm{H}\to {\mu }^{+}n$, in the NOvA near detector using a $1.2\times 10^{21}$ proton-on-target exposure in the NuMI beam. A selection based on topological and kinematic constraints yields 35,509 signal events in the hydrogen-rich ($10.8\%$) detector, providing the highest statistics of (anti)neutrino--hydrogen interactions measured to date. Backgrounds from (anti)neutrino interactions on heavier nuclei are constrained using dedicated data control samples, significantly reducing the related systematic uncertainties. We obtain a value $\sigma ({\bar{\nu }}_{\mu }\mathrm{H}\to {\mu }^{+}n)=0.538\pm 0.009(\mathrm{stat})\pm 0.010(\mathrm{syst})\pm 0.055(\mathrm{flux})\times 10^{-38}$ cm${}^2$ for the total cross section at an average energy of 1.9 GeV, the most precise total cross-section measurement of this process to date. The combined statistical and non-flux systematic uncertainty is more than four times smaller than the flux uncertainty, allowing a future use of this measurement to constrain the absolute ${\bar{\nu }}_{\mu }$ flux.

Comments: 11 pages (8 main and 3 supplemental), 10 figures (4 main and 6 supplemental)