Neutrino-argon cross-section measurements from the MicroBooNE experiment

MicroBooNE is a liquid argon time projection chamber (LArTPC) neutrino detector located along the Fermilab Booster Neutrino Beam and 8 degrees off-axis to the Neutrinos at the Main Injector beam. MicroBooNE collected data from both beams accumulating a large neutrino-argon scattering dataset containing hundreds of thousands of events. Understanding neutrino-argon interactions is crucial for the next generation of neutrino oscillation experiments including DUNE. MicroBooNE has developed pioneering methodologies and novel reconstruction tools in order to benchmark models at very high sensitivity across the interaction phase space, including for ultra-rare channels. This proceeding presents an overview of the most recent MicroBooNE neutrino interaction results. These measurements span inclusive, CC0$π$, and rare channels including $Λ$, $K^+$ and $η$ production, providing invaluable datasets for constraining backgrounds and improving the modeling of neutrino scattering critical for the broader LArTPC neutrino physics program.

💡 Research Summary

The MicroBooNE collaboration presents a comprehensive suite of neutrino‑argon interaction measurements obtained with its 85‑ton liquid argon time projection chamber (LArTPC) exposed to both the Fermilab Booster Neutrino Beam (BNB) and the NuMI beam. Using a data set corresponding to 1.3 × 10²¹ protons‑on‑target (POT), the experiment delivers high‑statistics results across a broad range of interaction topologies, from inclusive νμ charged‑current (CC) scattering to exclusive rare processes such as Λ, K⁺, and η production.

The first set of results focuses on inclusive νμ CC interactions. For the first time, MicroBooNE separates events by proton multiplicity (“0p” and “Np”) and provides double‑differential cross sections as a function of proton kinetic energy and multiplicity. A kinetic‑energy threshold of 35 MeV is applied; the 0p bin, which contains events with no reconstructed protons above this threshold, is best described by the GiBUU generator, which yields the lowest χ² despite under‑predicting higher‑energy proton yields. This highlights the sensitivity of low‑energy proton observables to nuclear‑medium effects and final‑state interactions (FSI).

The second major result concerns the CC0π (charged‑current, zero‑pion) channel. Using the full BNB exposure, MicroBooNE measures flux‑integrated double‑differential cross sections d²σ/(dcosθ_μ dp_μ) across a wide muon momentum range. The GiBUU and NEUT generators achieve p‑values above 5 %, indicating reasonable agreement with data, while several standard GENIE tunes show significant discrepancies, especially in regions where meson‑exchange currents (MEC) and resonance contributions overlap. These findings provide a stringent benchmark for models that must simultaneously describe quasielastic, resonant, and deep‑inelastic scattering on argon.

Rare‑process measurements are also reported. The experiment observes K⁺ and Λ production with cross sections of order 10⁻⁴¹ cm² per nucleon, and sets limits on η‑meson production. These channels probe strange‑quark dynamics and intermediate‑state resonances that are otherwise inaccessible in more inclusive analyses, offering valuable input for beyond‑Standard‑Model searches that rely on precise background modeling.

A novel analysis of CC1p0π (single‑proton, zero‑pion) events is presented to assess neutrino‑direction reconstruction. By defining a vector b = p_μ + p_p and computing the angle θ_vis = arccos(b·ẑ/|b|) relative to the beam direction, the study demonstrates that the majority of events achieve a direction resolution better than 5°, with only a small tail extending beyond 30°. The work further explores the dependence of θ_vis on reconstructed neutrino energy, struck‑nucleon momentum, and missing momentum, showing that regions with high missing momentum are dominated by neutron‑induced energy loss and multi‑neutrino pile‑up. Comparisons of three GENIE FSI configurations (G18T with hA2018, G18b with hN2018, and G18d with GEANT4‑Bertini) reveal comparable shape agreement, but statistical uncertainties currently preclude a decisive discrimination among the models.

Overall, the MicroBooNE results constitute a high‑precision data set that challenges existing neutrino‑nucleus interaction generators across multiple kinematic regimes. The inclusive νμ CC and CC0π measurements provide critical constraints on the balance of quasielastic, resonant, and multinucleon processes, while the rare‑channel observations open new windows on strange‑particle production. The demonstrated capability to reconstruct the incoming neutrino direction with sub‑5° accuracy using single‑proton topologies offers a powerful tool for atmospheric‑neutrino analyses and future LArTPC experiments such as DUNE and the Short‑Baseline Neutrino program. By delivering cross‑section measurements with statistical and systematic uncertainties at the few‑percent level, MicroBooNE directly supports the goal of reducing interaction‑model systematics to the sub‑percent regime required for next‑generation CP‑violation and mass‑hierarchy studies.