First Constraints on Light Sterile Neutrino Oscillations from Combined Appearance and Disappearance Searches with the MicroBooNE Detector

This document was prepared by the MicroBooNE Collaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. MicroBooNE is supported by the following: the U.S. Department of Energy, Office of Science, Offices of High Energy Physics and Nuclear Physics; the U.S. National Science Foundation; the Swiss National Science Foundation; the Science and Technology Facilities Council (STFC), part of the United Kingdom Research and Innovation; the Royal Society (United Kingdom); and the UK Research and Innovation (UKRI) Future Leaders Fellowship. Additional support for the laser calibration system and cosmic ray tagger was provided by the Albert Einstein Center for Fundamental Physics, Bern, Switzerland. We also acknowledge the contributions of technical and scientific staff to the design, construction, and operation of the MicroBooNE detector as well as the contributions of past collaborators to the development of MicroBooNE analyses, without whom this Letter would not have been possible. For the purpose of open access, the authors have applied a Creative Commons Attribution (CC BY) public copyright license to any author accepted manuscript version arising from this submission.We present a search for eV-scale sterile neutrino oscillations in the MicroBooNE liquid argon detector, simultaneously considering all possible appearance and disappearance effects within the 3+1 active-to-sterile neutrino oscillation framework. We analyze the neutrino candidate events for the recent measurements of charged-current νe and νμ interactions in the MicroBooNE detector, using data corresponding to an exposure of 6.37×1020 protons on target from the Fermilab booster neutrino beam. We observe no evidence of light sterile neutrino oscillations and derive exclusion contours at the 95% confidence level in the plane of the mass-squared splitting Δm241 and the sterile neutrino mixing angles θμe and θee, excluding part of the parameter space allowed by experimental anomalies. Cancellation of νe appearance and νe disappearance effects due to the full 3+1 treatment of the analysis leads to a degeneracy when determining the oscillation parameters, which is discussed in this Letter and will be addressed by future analyses.Fermi Research Alliance, LLC DE-AC02-07CH11359High Energy Physics and Nuclear PhysicsUnited Kingdom Research and InnovationNational Science FoundationU.S. Department of EnergyOffice of ScienceUK Research and InnovationScience and Technology Facilities CouncilRoyal SocietySchweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschun

Search for an anomalous excess of charged-current quasielastic νe interactions with the MicroBooNE experiment using Deep-Learning-based reconstruction

We present a measurement of the νe-interaction rate in the MicroBooNE detector that addresses the observed MiniBooNE anomalous low-energy excess (LEE). The approach taken isolates neutrino interactions consistent with the kinematics of charged-current quasielastic (CCQE) events. The topology of such signal events has a final state with one electron, one proton, and zero mesons (1e1p). Multiple novel techniques are employed to identify a 1e1p final state, including particle identification that use two methods of Deep-Learning-based image identification and event isolation using a boosted decision-tree ensemble trained to recognize two-body scattering kinematics. This analysis selects 25 νe-candidate events in the reconstructed neutrino energy range of 200–1200 MeV, while 29.0 1.9ðsysÞ 5.4ðstatÞ are predicted when using νμ CCQE interactions as a constraint. We use a simplified model to translate the MiniBooNE LEE observation into a prediction for a νe signal in MicroBooNE. A Δχ2 test statistic, based on the combined Neyman–Pearson χ2 formalism, is used to define frequentist confidence intervals for the LEE signal strength. Using this technique, in the case of no LEE signal, we expect this analysis to exclude a normalization factor of 0.75 (0.98) times the median MiniBooNE LEE signal strength at 90% (2σ) confidence level, while the MicroBooNE data yield an exclusion of 0.25 (0.38) times the median MiniBooNE LEE signal strength at 90% (2σ) confidence level.United States Department of Energy (DOE) University of ChicagoUnited States Department of Energy (DOE)Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359United States Department of Energy (DOE)UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC) Science and Technology Development Fund (STDF)United Kingdom Research and InnovationRoyal Society of LondonEuropean Commissio

Search for Neutrino-Induced Neutral-Current Δ Radiative Decay in MicroBooNE and a First Test of the MiniBooNE Low Energy Excess under a Single-Photon Hypothesis

This document was prepared by the MicroBooNE Collaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. MicroBooNE is supported by the U.S. Department of Energy, Office of Science, Offices of High Energy Physics and Nuclear Physics; the U.S. National Science Foundation; the Swiss National Science Foundation; the Science and Technology Facilities Council (STFC), part of the United Kingdom Research and Innovation; the Royal Society (United Kingdom); and The European Union’s Horizon 2020 Marie Skłodowska-Curie Actions. Additional support for the laser calibration system and cosmic ray tagger was provided by the Albert Einstein Center for Fundamental Physics, Bern, Switzerland.We report results from a search for neutrino-induced neutral current (NC) resonant Δð1232Þ baryon production followed by Δ radiative decay, with a h0.8i GeV neutrino beam. Data corresponding to MicroBooNE’s first three years of operations (6.80 × 1020 protons on target) are used to select single-photon events with one or zero protons and without charged leptons in the final state (1γ1p and 1γ0p, respectively). The background is constrained via an in situ high-purity measurement of NC π0 events, made possible via dedicated 2γ1p and 2γ0p selections. A total of 16 and 153 events are observed for the 1γ1p and 1γ0p selections, respectively, compared to a constrained background prediction of 20.5 3.65ðsystÞ and 145.1 13.8ðsystÞ events. The data lead to a bound on an anomalous enhancement of the normalization of NC Δ radiative decay of less than 2.3 times the predicted nominal rate for this process at the 90% confidence level (C.L.). The measurement disfavors a candidate photon interpretation of the MiniBooNE low-energy excess as a factor of 3.18 times the nominal NC Δ radiative decay rate at the 94.8% C.L., in favor of the nominal prediction, and represents a greater than 50-fold improvement over the world’s best limit on single-photon production in NC interactions in the sub-GeV neutrino energy range.European Union’s Horizon 2020 Marie Skłodowska-Curie ActionsFermi Research Alliance, LLC DE-AC02-07CH11359High Energy Physics and Nuclear PhysicsUnited Kingdom Research and InnovationNational Science FoundationU.S. Department of EnergyOffice of ScienceScience and Technology Facilities CouncilRoyal SocietySchweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschun

Search for an anomalous excess of inclusive charged-current νe interactions in the MicroBooNE experiment using Wire-Cell reconstruction

We report a search for an anomalous excess of inclusive charged-current (CC) nu(e) interactions using the Wire-Cell event reconstruction package in the MicroBooNE experiment, which is motivated by the previous observation of a low-energy excess (LEE) of electromagnetic events from the MiniBooNE experiment. With a single liquid argon time projection chamber detector, the measurements of nu(mu) CC interactions as well as pi(0) interactions are used to constrain signal and background predictions of nu(e) CC interactions. A data set collected from February 2016 to July 2018 corresponding to an exposure of 6.369 x 10(20) protons on target from the Booster Neutrino Beam at FNAL is analyzed. With x representing an overall normalization factor and referred to as the LEE strength parameter, we select 56 fully contained nu(e) CC candidates while expecting 69.6 +/- 8.0 (stat.) +/- 5.0 (sys.) and 103.8 +/- 9.0 (stat.) +/- 7.4 (sys.) candidates after constraints for the absence (eLEE(x=0)) of the median signal strength derived from the MiniBooNE observation and the presence (eLEE(x=1)) of that signal strength, respectively. Under a nested hypothesis test using both rate and shape information in all available channels, the best-fit x is determined to be 0 (eLEE(x= 0)) with a 95.5% confidence level upper limit of x at 0.502. Under a simple-vs-simple hypotheses test, the eLEE(x=1 )hypothesis is rejected at 3.75 sigma, while the eLE.E-x=0, hypothesis is shown to be consistent with the observation at 0.45 sigma. In the context of the eLEE model, the estimated 68.3% confidence interval of the nu(e) CC hypothesis to explain the LEE observed in the MiniBooNE experiment is disfavored at a significance level of more than 2.6 sigma (3.0 sigma) considering MiniBooNE's full (statistical) uncertainties.Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359United States Department of Energy (DOE) National Science Foundation (NSF)Swiss National Science Foundation (SNSF)European CommissionUK Research & Innovation (UKRI)Science & Technology Facilities Council (STFC)Royal Society of LondonEuropean Union's Horizon 2020 Marie Sklodowska-Curie ActionsAlbert Einstein Center for Fundamental Physics, Bern, Switzerlan

Search for an anomalous excess of charged-current νe interactions without pions in the final state with the MicroBooNE experiment

This article presents a measurement of νe interactions without pions in the final state using the MicroBooNE experiment and an investigation into the excess of low-energy electromagnetic events observed by the MiniBooNE Collaboration. The measurement is performed in exclusive channels with (1eNp0π) and without (1e0p0π) visible final-state protons using 6.86 × 1020 protons on target of data collected from the Booster Neutrino Beam at Fermilab. Events are reconstructed with the Pandora pattern recognition toolkit and selected using additional topological information from the MicroBooNE liquid argon time projection chamber. Using a goodness-of-fit test, the data are found to be consistent with the predicted number of events with nominal flux and interaction models with a p value of 0.098 in the two channels combined. A model based on the low-energy excess observed in MiniBooNE is introduced to quantify the strength of a possible νe excess. The analysis suggests that, if an excess is present, it is not consistent with a scaling of the νe contribution to the flux as predicted by the signal model used in the analysis. Combined, the 1eNp0π and 1e0p0π channels do not give a conclusive indication about the tested model, but separately, they both disfavor the low-energy excess model at > 90% C:L: The observation in the most sensitive 1eNp0π channel is below the prediction and consistent with no excess. In the less sensitive 1e0p0π channel, the observation at low energy is above the prediction, while overall there is agreement over the full energy spectrum.Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359United States Department of Energy (DOE)National Science Foundation (NSF)Swiss National Science Foundation (SNSF)European CommissionUK Research & Innovation (UKRI)Science & Technology Facilities Council (STFC)Science and Technology Development Fund (STDF)United Kingdom Research and InnovationRoyal Society of LondonEuropean Commissio

Measurement of the flux-averaged inclusive charged-current electron neutrino and antineutrino cross section on argon using the NuMI beam and the MicroBooNE detector

This document was prepared by the MicroBooNE Collaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. MicroBooNE is supported by the following: the U.S. Department of Energy, Office of Science, Offices of High Energy Physics and Nuclear Physics; the U.S. National Science Foundation; the Swiss National Science Foundation; the Science and Technology Facilities Council (STFC), part of the United Kingdom Research and Innovation; and The Royal Society (United Kingdom). Additional support for the laser calibration system and cosmic-ray tagger was provided by the Albert Einstein Center for Fundamental Physics, Bern, Switzerland.We present a measurement of the combined nu(e) + (nu) over bar (e) flux-averaged charged-current inclusive cross section on argon using data from the MicroBooNE liquid argon time projection chamber (LArTPC) at Fermilab. Using the off-axis flux from the NuMI beam, MicroBooNE has reconstructed 214 candidate nu(e) + (nu) over bar (e) interactions with an estimated exposure of 2.4 x 10(20) protons on target. Given the estimated purity of 38.6%, this implies the observation of 80 nu(e) + (nu) over bar (e) events in argon, the largest such sample to date. The analysis includes the first demonstration of a fully automated application of a dE/dx-based particle discrimination technique of electron- and photon-induced showers in a LArTPC neutrino detector. The main background for this first nu(e) analysis is cosmic ray contamination. Significantly higher purity is expected in underground detectors, as well as with next-generation reconstruction algorithms. We measure the nu(e) + (nu) over bar (e) flux-averaged charged-current total cross section to be 6.84 +/- 1.51(stat) +/- 2.33(sys) x 10(-39) cm(2)/nucleon, for neutrino energies above 250 MeVand an average neutrino flux energy of 905 MeV when this threshold is applied. The measurement is sensitive to neutrino events where the final state electron momentum is above 48 MeV/c, includes the entire angular phase space of the electron, and is in agreement with the theoretical predictions from GENIE and NuWro. This measurement is also the first demonstration of electron-neutrino reconstruction in a surface LArTPC in the presence of cosmic-ray backgrounds, which will be a crucial task for surface experiments like those that comprise the short-baseline neutrino program at Fermilab.Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359United States Department of Energy (DOE) National Science Foundation (NSF)Swiss National Science Foundation (SNSF)European CommissionScience and Technology Facilities Council (STFC), United Kingdom Research and InnovationRoyal Society of Londo

First Measurement of Quasielastic Λ Baryon Production in Muon Antineutrino Interactions in the MicroBooNE Detector

This document was prepared by the MicroBooNE collaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. MicroBooNE is supported by the following: the U.S. Department of Energy, Office of Science, Offices of High Energy Physics and Nuclear Physics; the U.S. National Science Foundation; the Swiss National Science Foundation; the Science and Technology Facilities Council (STFC), part of the United Kingdom Research and Innovation; the Royal Society (United Kingdom); and the UK Research and Innovation (UKRI) Future Leaders Fellowship. Additional support for the laser calibration system and cosmic ray tagger was provided by the Albert Einstein Center for Fundamental Physics, Bern, Switzerland. We also acknowledge the contributions of technical and scientific staff to the design, construction, and operation of the MicroBooNE detector as well as the contributions of past collaborators to the development of MicroBooNE analyses, without whom this work would not have been possible.We present the first measurement of the cross section of Cabibbo-suppressed Λ baryon production, using data collected with the MicroBooNE detector when exposed to the neutrinos from the main injector beam at the Fermi National Accelerator Laboratory. The data analyzed correspond to 2.2×10^{20} protons on target running in neutrino mode, and 4.9×10^{20} protons on target running in anti-neutrino mode. An automated selection is combined with hand scanning, with the former identifying five candidate Λ production events when the signal was unblinded, consistent with the GENIE prediction of 5.3±1.1 events. Several scanners were employed, selecting between three and five events, compared with a prediction from a blinded Monte Carlo simulation study of 3.7±1.0 events. Restricting the phase space to only include Λ baryons that decay above MicroBooNE's detection thresholds, we obtain a flux averaged cross section of 2.0_{-1.7}^{+2.2}×10^{-40}  cm^{2}/Ar, where statistical and systematic uncertainties are combined.U.S. Department of Energy, Office of Science, HEP User Facility: Fermi National Accelerator Laboratory (Fermilab)Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359U.S. Department of Energy, Office of Science, Offices of High Energy Physics and Nuclear PhysicsU.S. National Science FoundationSwiss National Science FoundationUnited Kingdom Research and Innovation, Science and Technology Facilities Council (STFC)Royal SocietyUK Research and Innovation (UKRI) Future Leaders FellowshipCentro Albert Einstein de Física Fundamental, Berna, Suiza.MicroBooN

First Measurement of Energy-Dependent Inclusive Muon Neutrino Charged-Current Cross Sections on Argon with the MicroBooNE Detector

This document was prepared by the MicroBooNE Collaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. MicroBooNE is supported by the following: the U.S. Department of Energy, Office of Science, Offices of High Energy Physics and Nuclear Physics; the U.S. National Science Foundation; the Swiss National Science Foundation; the Science and Technology Facilities Council (STFC), part of the United Kingdom Research and Innovation; the Royal Society (United Kingdom); and the European Union’s Horizon 2020 Marie Sklodowska-Curie Actions. Additional support for the laser calibration system and cosmic ray tagger was provided by the Albert Einstein Center for Fundamental Physics, Bern, Switzerland. We also acknowledge the contributions of technical and scientific staff to the design, construction, and operation of the MicroBooNE detector as well as the contributions of past collaborators to the development of MicroBooNE analyses, without whom this work would not have been possible.We report a measurement of the energy-dependent total charged-current cross section σ(Eν) for inclusive muon neutrinos scattering on argon, as well as measurements of flux-averaged differential cross sections as a function of muon energy and hadronic energy transfer (ν). Data corresponding to 5.3×1019 protons on target of exposure were collected using the MicroBooNE liquid argon time projection chamber located in the Fermilab booster neutrino beam with a mean neutrino energy of approximately 0.8 GeV. The mapping between the true neutrino energy Eν and reconstructed neutrino energy Erecν and between the energy transfer ν and reconstructed hadronic energy Erechad are validated by comparing the data and Monte Carlo (MC) predictions. In particular, the modeling of the missing hadronic energy and its associated uncertainties are verified by a new method that compares the Erechad distributions between data and a MC prediction after constraining the reconstructed muon kinematic distributions, energy, and polar angle to those of data. The success of this validation gives confidence that the missing energy in the MicroBooNE detector is well modeled and underpins first-time measurements of both the total cross section σ(Eν) and the differential cross section dσ/dν on argon.High Energy Physics and Nuclear PhysicsUnited Kingdom Research and InnovationNational Science FoundationU.S. Department of EnergyOffice of ScienceScience and Technology Facilities CouncilRoyal SocietySchweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschun

Cosmic ray muon clustering for the MicroBooNE liquid argon time projection chamber using sMask-RCNN

In this article, we describe a modified implementation of Mask Region-based Convolutional Neural Networks (Mask-RCNN) for cosmic ray muon clustering in a liquid argon TPC and applied to MicroBooNE neutrino data. Our implementation of this network, called sMask-RCNN, uses sparse submanifold convolutions to increase processing speed on sparse datasets, and is compared to the original dense version in several metrics. The networks are trained to use wire readout images from the MicroBooNE liquid argon time projection chamber as input and produce individually labeled particle interactions within the image. These outputs are identified as either cosmic ray muon or electron neutrino interactions. We find that sMask-RCNN has an average pixel clustering efficiency of 85.9% compared to the dense network’s average pixel clustering efficiency of 89.1%. We demonstrate the ability of sMask-RCNN used in conjunction with MicroBooNE’s state-of-the-art Wire-Cell cosmic tagger to veto events containing only cosmic ray muons. The addition of sMask-RCNN to the Wire-Cell cosmic tagger removes 70% of the remaining cosmic ray muon background events at the same electron neutrino event signal efficiency. This event veto can provide 99.7% rejection of cosmic ray-only background events while maintaining an electron neutrino event-level signal efficiency of 80.1%. In addition to cosmic ray muon identification, sMask-RCNN could be used to extract features and identify different particle interaction types in other 3D-tracking detectors.Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359United States Department of Energy (DOE) National Science Foundation (NSF)Swiss National Science Foundation (SNSF)European CommissionUK Research & Innovation (UKRI)Science & Technology Facilities Council (STFC)Royal Society of LondonEuropean CommissionAlbert Einstein Center for Fundamental Physics, Bern, Switzerlan

Electromagnetic shower reconstruction and energy validation with Michel electrons and pi(0) samples for the deep-learning-based analyses in MicroBooNE

This document was prepared by the MicroBooNE collaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. MicroBooNE is supported by the following: the U.S. Department of Energy, Office of Science, Offices of High Energy Physics and Nuclear Physics; the U.S. National Science Foundation; the Swiss National Science Foundation; the Science and Technology Facilities Council (STFC), part of the United Kingdom Research and Innovation; the Royal Society (United Kingdom); and The European Union's Horizon 2020 Marie Sklodowska-Curie Actions. Additional support for the laser calibration system and cosmic ray tagger was provided by the Albert Einstein Center for Fundamental Physics, Bern, Switzerland.This article presents the reconstruction of the electromagnetic activity from electrons and photons (showers) used in the MicroBooNE deep learning-based low energy electron search. The reconstruction algorithm uses a combination of traditional and deep learning-based techniques to estimate shower energies. We validate these predictions using two nu(mu)-sourced data samples: charged/neutral current interactions with final state neutral pions and charged current interactions in which the muon stops and decays within the detector producing a Michel electron. Both the neutral pion sample and Michel electron sample demonstrate agreement between data and simulation. Further, the absolute shower energy scale is shown to be consistent with the relevant physical constant of each sample: the neutral pion mass peak and the Michel energy cutoff.Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359United States Department of Energy (DOE) National Science Foundation (NSF)Swiss National Science Foundation (SNSF)European CommissionScience and Technology Facilities Council (STFC) , part of the United Kingdom Research and InnovationRoyal Society of LondonEuropean Union's Horizon 2020 Marie Sklodowska-Curie ActionsAlbert Einstein Center for Fundamental Physics, Bern, Switzerlan