Search for an Anomalous Production of Charged-Current $\nu_e$ Interactions Without Visible Pions Across Multiple Kinematic Observables in MicroBooNE

TL;DR

This study analyzes low-energy electron-neutrino interactions in MicroBooNE to test the MiniBooNE excess, using five years of data and two models, ultimately excluding an electron-like explanation at over 99% confidence.

Contribution

First measurement using all five years of MicroBooNE data to investigate the MiniBooNE excess and test electron-neutrino interaction models.

Findings

Data agrees with predictions within 26.7% p-value

Excludes electron-like interpretation of MiniBooNE excess at >99% CL

Models modifying interaction rates do not fully account for observed data

Abstract

This Letter presents an investigation of low-energy electron-neutrino interactions in the Fermilab Booster Neutrino Beam by the MicroBooNE experiment, motivated by the excess of electron-neutrino-like events observed by the MiniBooNE experiment. This is the first measurement to use data from all five years of operation of the MicroBooNE experiment, corresponding to an exposure of $1.11\times 10^{21}$ protons on target, a $70\%$ increase on past results. Two samples of electron neutrino interactions without visible pions are used, one with visible protons and one without any visible protons. The MicroBooNE data show reasonable agreement with the nominal prediction, with $p$-values $\ge 26.7\%$ when the two $\nu_e$ samples are combined, though the prediction exceeds the data in limited regions of phase space. The data is further compared to two empirical models that modify the predicted rate of electron-neutrino interactions in different variables in the simulation to match the unfolded MiniBooNE low energy excess. In the first model, this unfolding is performed as a function of electron neutrino energy, while the second model aims to match the observed shower energy and angle distributions of the MiniBooNE excess. This measurement excludes an electron-like interpretation of the MiniBooNE excess based on these models at $> 99\%$ CL$_\mathrm{s}$ in all kinematic variables.