Sensitivity to Sterile Neutrinos with Elastic Neutrino-Electron and Highly Elastic Neutrino-Nucleus Scattering in the DUNE Near Detector

Abstract

The Deep Underground Neutrino Experiment (DUNE) is a next-generation neutrino experiment designed for precision measurements of long-baseline three-flavor neutrino oscillations. The DUNE Near Detector (ND) is also sensitive to short-baseline oscillations arising from mixing with an eV-scale sterile neutrino. In this paper, we present a sensitivity study for sterile-neutrino oscillations in the $3+1$ framework using three complementary event samples in the simulated DUNE ND: highly elastic ${\nu }_{\mu }$ charged-current (CC), highly elastic ${\nu }_e$ CC, and neutrino-electron elastic-scattering ($\nu +e$) events. These highly exclusive samples are chosen to reduce neutrino-interaction and flux uncertainties: the low-hadronic-energy CC selections enhance the correlation between reconstructed lepton energy and neutrino energy, while the precisely calculable $\nu +e$ cross section provides an independent constraint on the neutrino flux. Residual interaction-model dependence remains in the CC samples. The statistical analysis considers $|U_{e4}{|}^2$, $|U_{\mu 4}{|}^2$, $|U_{\tau 4}{|}^2$, and $\Delta m^2$, with sensitivity results presented as fixed-$\Delta m^2$ slices for $|U_{\tau 4}{|}^2=0$. The strongest sensitivity occurs for $4\lesssim \Delta m^2\lesssim 10{\mathrm{eV}}^2$, where oscillations produce resolvable distortions of the reconstructed-energy spectra. For one year of on-axis forward-horn-current running, the 90\% confidence-level sensitivity reaches approximately $|U_{\mu 4}{|}^2\simeq 0.01$ and $|U_{e4}{|}^2\simeq 0.015$, depending on the value of the other mixing parameter.