Implications of MicroBooNE's low sensitivity to electron antineutrino interactions in the search for the MiniBooNE excess

TL;DR

This paper discusses how MicroBooNE's low sensitivity to electron antineutrino interactions affects the interpretation of the MiniBooNE excess, suggesting that the excess could be due to antineutrinos rather than neutrinos.

Contribution

It demonstrates that liquid argon detectors have limited sensitivity to antineutrino interactions in the relevant energy range, impacting the analysis of the MiniBooNE low-energy excess.

Findings

MicroBooNE's results are consistent with an antineutrino origin of the excess.

Liquid argon detectors have suppressed cross sections for low-energy antineutrinos.

The scenario where the excess is due to antineutrinos cannot be ruled out at 2σ confidence level.

Abstract

The MicroBooNE experiment searched for an excess of electron-neutrinos in the Booster Neutrino Beam (BNB), providing direct constraints on $\nu_e$-interpretations of the MiniBooNE low-energy excess (LEE). In this article, we show that if the MiniBooNE LEE is caused instead by an excess of $\overline{\nu}_e$, then liquid argon detectors, such as MicroBooNE, SBND and ICARUS, would have poor sensitivity to it. This is due to a strong suppression of $\overline{\nu}_e -{}^{40}$Ar cross sections in the low-energy region of the excess. The MicroBooNE results are consistent at the $2\sigma$~C.L with a scenario in which the MiniBooNE excess is sourced entirely by $\overline{\nu}_e$ interactions. The opportune location of ANNIE, a Gd-loaded water Cherenkov detector, allows for a direct search for a $\overline{\nu}_e$ flux excess in the BNB using inverse-beta-decay events.