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A Joint Measurement of $\nu_{\mu}$-Disappearance and $\nu_{e}$e-Appearance in the NuMI beam using the NOvA Experiment
The discovery of neutrino oscillations provides the first indication of a lepton flavor violating (LFV) process, one that isn't predicted by the Standard Model. As such, NOvA is part of a rich experimental program to constrain unknown parameters in the neutrino oscillation model, described for three neutrino flavors using the PMNS unitary matrix. It is a long baseline experiment utilizing two detectors, a Near Detector at Fermilab and a Far Detector in Ash River, Minnesota for a total baseline of 810 km. It receives a predominantly ${\nu_\mu}/\overline{\bar\nu_\mu}$ beam peaking at 1:8 GeV from the NuMI beam facility at Fermilab. There are four oscillation channels used in the analysis, ${\nu_\mu} \to {\nu_\mu}$, ${\nu_\mu} \to {\nu_e}$, ${\overline{\nu}_\mu} \to {\overline{\nu}_\mu}$ and ${\overline{\nu}_\mu} \to {\overline{\nu}_e }$. With a total exposure of 13:6_10$^{20}$ and 12:5_10$^{20}$ protons on target for the neutrino and anti-neutrino beam modes respectively, 82 candidates are seen in the ${\nu_\mu} \to {\nu_e}$ channel for a total predicted backgroundof 26:8 events. Similarly, 33 candidates are seen in the corresponding anti-neutrino channel for a total predicted background of 14:0 events. In the ${\nu_\mu} \to {\nu_\mu}$ $(\overline{\nu}_\mu \to \overline{\nu}_\mu}$ channel, 211 (105) candidates are seen with an expectation of 1156.1 (488.1) events at no oscillations.
Recent results from NOvA
We present the most recent 3-flavor neutrino oscillation results from the NOvA long-baseline experiment, using a joint fit of $\nu_\mu \to \nu_\mu$, $\bar{\nu}_{\mu} \to \bar{\nu}_{\mu}$, $\nu_\mu \to \nu_{e}$, and $\bar{\nu}_{\mu}\to \bar{\nu}_{e}$ channels, and an accumulated exposure of $13.6 \times 10^{20}$ protons-on-target of neutrino beam and $12.5 \times 10^{20}$ protons-on-target of antineutrino beam. The best-fit values for the atmospheric parameters are $\Delta m^2_{32} = (2.41\pm0.07)\times 10^{-3}$ eV$^2$, $\sin^2\theta_{23} = 0.57^{+0.03}_{-0.04}$ and $\delta_{CP} = (0.82^{+0.27}_{-0.87}) \pi$. The data disfavor combinations of oscillation parameters that lead to large asymmetries between the rates of $\nu_{e}$ vs $\bar{\nu}_{e}$ appearance.
Improvement of the NOvA Near Detector Event Reconstruction and Primary Vertexing through the Application of Machine Learning Methods
The purpose of this work is to examine the application of a deep learning model in event reconstruction of neutrino interactions. The challenges faced in event reconstruction include the placement of an accurate primary neutrino interaction vertex which is used to support the particle track and prong algorithms. The result of accurate primary vertex ensures all particles involved in a neutrino interaction are included. We propose a regression-based Convolutional Neural Network (CNN) method to predict the primary vertex of a particle interaction. We show that with raw two-dimensional pixel map views as input, the regression-based CNN can predict the primary vertex in all three coordinates. This work is applied as part of the NOvA (NuMI Off-axis $\nu_e$ Appearance) near detector reconstruction efforts. The primary vertex predicted by the regression-based CNN model shows promising results for future applications. This deep learning method can be extended to secondary vertexing through a Kernel Density Estimate algorithm discussed in this work.
NOvA Constraints on CP-Violating Non-Standard Interactions
This poster shows the results of work of search for charge-parity (CP) symmetry violating non-standard interactions (NSI) of neutrinos with matter using the NOvA Experiment, and examines their effects on the determination of the standard oscillation parameters.
Search for 2p2h Interactions in NOvA
Poster describing research into the search for 2p2h interactions in the NOvA near detector.
Study of the Neutrino Magnetic Moment with the NOvA Near Detector
Predicted by the Standard Model as theoretical, massless particles, neutrinos have been the subject of many experiments since their first detection. It is now experimentally confirmed that neutrinos do have mass necessitating an extension to the Standard Model. Such an extension allows for other surprising neutrino properties, such as a neutrino magnetic moment, nuMM. While neutrinos are observed to be neutral and do not couple to photons at leading order, higher order expansion of the interaction allows for coupling to the photon to occur and gives rise to a nuMM through quantum loop effects. This is a useful property for studying the Dirac or Majorana nature of neutrinos, as the predicted value of the magnetic moment would differ. This talk focuses on an introduction to the nuMM as well as discusses the current status of work being done on NOvA utilizing the Near Detector to obtain an upper limit on the nuMM value.
NOvA's Current and Future Sterile Neutrino Searches
The NOvA experiment's most recent search for eV-scale sterile neutrinos under a 3+1 model simultaneously analyses muon neutrino and neutral current datasets from the NuMI beam at its Near ($\sim$\qty1{km} baseline) and Far (\qty{810}{km} baseline) detectors to look for oscillations consistent with a sterile neutrino. The analysis is systematically limited in the region of parameter space where $Δm^2_{41} \gtrsim 1~\mathrm{eV}^2$. This region of parameter space is preferred by sterile neutrino interpretations of current experimental anomalies and so improving sensitivity here is high-priority. These proceedings present our current search strategy, and discusses future plans to include data from a second beamline, the Booster Neutrino Beam, to improve our sensitivity in systematics-dominated regions of parameter space.
First inclusive triple-differential measurement of the muon-antineutrino charged-current cross section using the NOvA Near Detector
We present the first measurement of the triple-differential muon antineutrino charged-current inclusive cross section, using the NOvA Near Detector and $12.5 \times 10^{20}$ protons on target in the NuMI beam. This sample of muon antineutrino interactions is the largest ever published, with approximately 1 million selected muon antineutrino events. The triple-differential cross section is measured in the final-state kinetic energy, the scattering angle, and the available energy of the interaction. The measurement enables phase-space regions populated by differing neutrino reaction processes to be isolated and the transition regions between them to be defined. The results are compared with the predictions of the main event generators used in the neutrino community and we observe energy- and angle-dependent discrepancies across a broad range of energies and interaction types
Measurement of the $\bar ν_μ-$Hydrogen Charged-Current Quasi-Elastic Cross Section using the NOvA Near Detector
We report a measurement of the total cross section for muon antineutrino charged-current quasi-elastic scattering on hydrogen, $\bar ν_μ{\rm H} \to μ^+ n$, in the NOvA near detector using a $1.2\times10^{21}$ proton-on-target exposure in the NuMI beam. A selection based on topological and kinematic constraints yields 35,509 signal events in the hydrogen-rich ($10.8\%$) detector, providing the highest statistics of (anti)neutrino--hydrogen interactions measured to date. Backgrounds from (anti)neutrino interactions on heavier nuclei are constrained using dedicated data control samples, significantly reducing the related systematic uncertainties. We obtain a value $σ(\bar ν_μ{\rm H} \to μ^+ n) = 0.538 \pm 0.009 ({\rm stat}) \pm 0.010 ({\rm syst}) \pm0.055 ({\rm flux}) \times 10^{-38}$ cm$^2$ for the total cross section at an average energy of 1.9 GeV, the most precise total cross-section measurement of this process to date. The combined statistical and non-flux systematic uncertainty is more than four times smaller than the flux uncertainty, allowing a future use of this measurement to constrain the absolute $\bar ν_μ$ flux.
Measurement of the $\bar ν_μ-$Hydrogen Charged-Current Quasi-Elastic Cross Section using the NOvA Near Detector
We report a measurement of the total cross section for muon antineutrino charged-current quasi-elastic scattering on hydrogen, $\bar ν_μ{\rm H} \to μ^+ n$, in the NOvA near detector using a $1.2\times10^{21}$ proton-on-target exposure in the NuMI beam. A selection based on topological and kinematic constraints yields 35,509 signal events in the hydrogen-rich ($10.8\%$) detector, providing the highest statistics of (anti)neutrino--hydrogen interactions measured to date. Backgrounds from (anti)neutrino interactions on heavier nuclei are constrained using dedicated data control samples, significantly reducing the related systematic uncertainties. We obtain a value $σ(\bar ν_μ{\rm H} \to μ^+ n) = 0.538 \pm 0.009 ({\rm stat}) \pm 0.010 ({\rm syst}) \pm0.055 ({\rm flux}) \times 10^{-38}$ cm$^2$ for the total cross section at an average energy of 1.9 GeV, the most precise total cross-section measurement of this process to date. The combined statistical and non-flux systematic uncertainty is more than four times smaller than the flux uncertainty, allowing a future use of this measurement to constrain the absolute $\bar ν_μ$ flux.
First Sterile Neutrino Search at NOvA Experiment Using both Neutrino and Anti-Neutrino Data
Neutrinos are among the most abundant fundamental particles in the universe, and yet they are so elusive that they pass through almost everything without leaving a trace. For decades, researchers have measured neutrino oscillations in great detail, refining our understanding of the theories. Yet, once again, neutrino shows their incredibly surprising nature through some recent experimental results, suggesting that our current understanding might be incomplete. Several experiments have observed an unexpected difference in the observed neutrino behaviour from what the Standard Model predicts, showing an excess in some cases (e.g. LSND, MiniBooNE) and a deficit of neutrino events in others (e.g. SAGE, GALLEX). These anomalies challenge our conventional theories of standard three neutrino flavors and phenomenologically motivate the sterile neutrino hypothesis, which does not interact through the usual weak force. While some results appear consistent with this idea, others have found no supporting evidence (e.g. MicroBooNE), leaving the question unanswered. NOvA is one such long-baseline neutrino experiment with its Near Detector (ND) at Fermilab and a Far Detector (FD) at 810 km in Minnesota. It uses the NuMI beam as its primary source of neutrinos for oscillation studies. Its two-detector setup, extended baseline, and ability to conduct combined $\nu$-$\bar\nu$ analyses position it to explore these phenomena in new ways. We use the joint $\nu_{\mu}$ and neutral current (NC) disappearance channels to probe active-sterile mixing in the 3+1 model. This analysis utilizes a data sample of 27$\times$10$^{20}$ protons on target (POT) in neutrino mode and 12.5$\times$10$^{20}$ protons on target (POT) in antineutrino mode. We found no evidence of sterile neutrino at 90$\%$ C.L. We present the limits in $\sin^{2}\theta_{24}$ vs $\Delta m^{2}_{41}$, $\sin^{2}\theta_{34}$ vs $\Delta m^{2}_{41}$, and $\sin^{2}2\theta_{\mu\tau}$ vs $\Delta m^{2}_{41}$ parameter spaces. The limits provided by this analysis are world leading in most of the parameter spaces.
Extended search for supernovalike neutrinos in NOvA coincident with LIGO/Virgo detections
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Domain Generalization with Machine Learning in the NOvA Experiment
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First neutrino oscillation measurements in NOvA
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Neutrino oscillations with the MINOS, MINOS+, T2K, and NOvA experiments
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