Measurements of differential charged-current cross sections on argon for electron neutrinos with final-state protons in MicroBooNE

TL;DR

This paper reports flux-integrated, single-differential cross sections for electron-neutrino charged-current interactions on argon with at least one proton and no pions in the final state, using NuMI beam data collected by MicroBooNE. The analysis leverages a robust LArTPC reconstruction pipeline, Pandora-based event topology, and a Wiener-SVD unfolding to produce unfolded cross sections as functions of $E_e$, $E_{ ext{visible}}$, and $\cos\theta_{ep}$, along with the total cross section. The result, $[4.1 \pm 0.4\,(stat.) \pm 1.2\,(syst.)] \times 10^{-39}\ \mathrm{cm^2/nucleon}$, is consistent with predictions from NEUT, NuWro, GiBUU, and GENIE within uncertainties, highlighting a flux-dominated systematic and the need for more off-axis hadron-production data. The work demonstrates the feasibility of precise exclusive ν_e measurements on argon with LArTPCs and sets the stage for enhanced precision with future NuMI data and improved reconstruction, including proton-multiplicity unfolding. This advances neutrino-oscillation and sterile-neutrino searches by improving the modeling of ν_e interactions in argon targets used by next-generation experiments.

Abstract

This work presents single-differential electron-neutrino charged-current cross sections on argon measured using the MicroBooNE detector at the Fermi National Accelerator Laboratory. The analysis uses data recorded when the Neutrinos at the Main Injector beam was operating in both neutrino and antineutrino modes, with exposures of $2 \times 10^{20}$ and $5 \times 10^{20}$ protons on target, respectively. A selection algorithm targeting electron-neutrino charged-current interactions with at least one proton, one electron, and no pions in the final topology is used to measure differential cross sections as a function of outgoing electron energy, total visible energy, and opening angle between the electron and the most energetic proton. The interaction rate as a function of proton multiplicity is also reported. The total cross section is measured as [4.1 $\pm$ 0.4 (stat.) $\pm$ 1.2 (syst.)]$ $$\times 10^{-39} \mathrm{cm}^{2}/ \mathrm{nucleon}$. The unfolded cross-section measurements are compared to predictions from neutrino event generators commonly employed in the field. Good agreement is seen across all variables within uncertainties.

Figures (7)

• Figure 1: The position of MicroBooNE relative to the NuMI beamline from top (left) and side (right) views. The NuMI beamline is angled $3\degree$ downward. The distance from the NuMI target to MicroBooNE is approximately 675 meters. Neutrinos enter MicroBooNE at angles ${\approx}\,8-120\degree$ off the beamline. Most of the flux arriving at MicroBooNE originates from the target and, secondarily, the beam absorber.
• Figure 2: The neutrino flux prediction at MicroBooNE for the NuMI beam operating in FHC mode (a) and RHC mode (b) flux_public_note. Shown is the flux of $\nu_{e}$ (dashed red), $\bar{\nu}_{e}$ (dashed blue), $\nu_{\mu}$ (solid red), and $\bar{\nu}_{\mu}$ (solid blue).
• Figure 3: A selected signal candidate in the MicroBooNE NuMI Run 1 FHC dataset, as viewed from the collection plane. The event is characterized by a single electron-like electromagnetic shower and two proton-like tracks emanating from a common interaction vertex.
• Figure 4: Estimated event rates for FHC Run 1 (a) and RHC Run 3 (b) as a function of the output of the BDT trained to discriminate signal (orange) from various sources of background. The gray band represents the total MC+EXT uncertainty, as described in Sec. \ref{['uncertainties']}. Data is overlaid for comparison, shown in black with associated statistical uncertainties.
• Figure 5: Estimated signal (orange) and background (purple) predictions of the FHC+RHC selected events after the full selection (including the BDT threshold requirement) for reconstructed electron energy (a), visible energy (b), $\cos{\theta_{ep}}$ (c), and proton multiplicity (d). The rightmost bin for the electron energy, visible energy, and proton multiplicity distributions is overflow. The gray band represents the total MC+EXT uncertainty, as described in Sec. \ref{['uncertainties']}. Data is overlaid for comparison, shown in black with associated statistical uncertainties. The data/MC ratios are also shown, where again the gray band represents the total MC+EXT uncertainty.