The NOvA experiment has seen a 4.4σ signal of ν¯e appearance in a 2 GeV ν¯μ beam at a distance of 810 km. Using 12.33×1020 protons on target delivered to the Fermilab NuMI neutrino beamline, the ...experiment recorded 27 ν¯μ→ν¯e candidates with a background of 10.3 and 102 ν¯μ→ν¯μ candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Δm322|=2.48−0.06+0.11×10−3 eV2/c4 and sin2θ23 in the ranges from (0.53–0.60) and (0.45–0.48) in the normal neutrino mass hierarchy. The data exclude most values near δCP=π/2 for the inverted mass hierarchy by more than 3σ and favor the normal neutrino mass hierarchy by 1.9σ and θ23 values in the upper octant by 1.6σ.
We present updated results from the NOvA experiment for νμ→νμ and νμ→νe oscillations from an exposure of 8.85×1020 protons on target, which represents an increase of 46% compared to our previous ...publication. The results utilize significant improvements in both the simulations and analysis of the data. A joint fit to the data for νμ disappearance and νe appearance gives the best-fit point as normal mass hierarchy, Δm322=2.44×10−3 eV2/c4, sin2θ23=0.56, and δCP=1.21π. The 68.3% confidence intervals in the normal mass hierarchy are Δm322∈2.37,2.52×10−3 eV2/c4, sin2θ23∈0.43,0.51∪0.52,0.60, and δCP∈0,0.12π∪0.91π,2π. The inverted mass hierarchy is disfavored at the 95% confidence level for all choices of the other oscillation parameters.
This paper reports the first measurement using the NOvA detectors of nu sub(mu) disappearance in a nu sub(mu) beam. The analysis uses a 14 kton-equivalent exposure of 2.74x10 super(20) ...protons-on-target from the Fermilab NuMI beam. Assuming the normal neutrino mass hierarchy, we measure (ProQuest: Formulae and/or non-USASCII text omitted) and sin super(2)theta sub(23) in the range 0.38-0.65, both at the 68% confidence level, with two statistically degenerate best-fit points at sin super(2)theta sub(23)=0.4 3 and 0.60. Results for the inverted mass hierarchy are also presented.
We report results from the first search for sterile neutrinos mixing with active neutrinos through a reduction in the rate of neutral-current interactions over a baseline of 810 km between the NOvA ...detectors. Analyzing a 14-kton detector equivalent exposure of 6.05×1020 protons-on-target in the NuMI beam at Fermilab, we observe 95 neutral-current candidates at the Far Detector compared with 83.5±9.7(stat)±9.4(syst) events predicted assuming mixing only occurs between active neutrino species. No evidence for νμ→νs transitions is found. Interpreting these results within a 3+1 model, we place constraints on the mixing angles θ24<20.8° and θ34<31.2° at the 90% C.L. for 0.05 eV2≤Δm412≤0.5 eV2, the range of mass splittings that produce no significant oscillations over the Near Detector baseline.
Results are reported from an improved measurement of ν_{μ}→ν_{e} transitions by the NOvA experiment. Using an exposure equivalent to 6.05×10^{20} protons on target, 33 ν_{e} candidates are observed ...with a background of 8.2±0.8 (syst.). Combined with the latest NOvA ν_{μ} disappearance data and external constraints from reactor experiments on sin^{2}2θ_{13}, the hypothesis of inverted mass hierarchy with θ_{23} in the lower octant is disfavored at greater than 93% C.L. for all values of δ_{CP}.
The two-detector design of the NOvA neutrino oscillation experiment, in which two functionally identical detectors are exposed to an intense neutrino beam, aids in canceling leading order effects of ...cross-section uncertainties. However, limited knowledge of neutrino interaction cross sections still gives rise to some of the largest systematic uncertainties in current oscillation measurements. We show contemporary models of neutrino interactions to be discrepant with data from NOvA, consistent with discrepancies seen in other experiments. Adjustments to neutrino interaction models in GENIE are presented, creating an effective model that improves agreement with our data. We also describe systematic uncertainties on these models, including uncertainties on multi-nucleon interactions from a newly developed procedure using NOvA near detector data.
NOvA is a long-baseline neutrino oscillation experiment that measures oscillations in charged-current ν μ → ν μ (disappearance) and ν μ → ν e (appearance) channels, and their antineutrino ...counterparts, using neutrinos of energies around 2 GeV over a distance of 810 km. In this work we reanalyze the dataset first examined in our previous paper using an alternative statistical approach based on Bayesian Markov chain Monte Carlo. We measure oscillation parameters consistent with the previous results. We also extend our inferences to include the first NOvA measurements of the reactor mixing angle θ 13 , where we find 0.071 ≤ sin 2 2 θ 13 ≤ 0.107 , and the Jarlskog invariant, where we observe no significant preference for the C P -conserving value J = 0 over values favoring C P violation. We use these results to examine the effects of constraints from short-baseline measurements of θ 13 using antineutrinos from nuclear reactors when making NOvA measurements of θ 23 . Our long-baseline measurement of θ 13 is shown to be consistent with the reactor measurements, supporting the general applicability and robustness of the Pontecorvo-Maki-Nakagawa-Sakata framework for neutrino oscillations. Published by the American Physical Society 2024
The inclusive electron neutrino charged-current cross section is measured in the NOvA near detector using 8.02 x 1020 protons-on-target (POT) in the NuMI beam. The sample of GeV electron neutrino ...interactions is the largest analyzed to date and is limited by ≃ 17% systematic rather than the ≃ 7.4% statistical uncertainties. The double-differential cross section in final-state electron energy and angle is presented for the first time, together with the single-differential dependence on Q2 (squared four-momentum transfer) and energy, in the range 1 GeV ≤ Eν < 6 GeV. Detailed comparisons are made to the predictions of the GENIE, GiBUU, NEUT, and NuWro neutrino event generators. The data do not strongly favor a model over the others consistently across all three cross sections measured, though some models have especially good or poor agreement in the single differential cross section vs. Q2.
We report cross-section measurements of the final-state muon kinematics for vu charged-current interactions in the NOvA near detector using an accumulated 8.09 x 1020 protons on target in the NuMI ...beam. We present the results as a double-differential cross section in the observed outgoing muon energy and angle, as well as single-differential cross sections in the derived neutrino energy, Ev, and square of the four-momentum transfer, Q2. We compare the results to inclusive cross-section predictions from various neutrino event generators via χ2 calculations using a covariance matrix that accounts for bin-to-bin correlations of systematic uncertainties. These comparisons show a clear discrepancy between the data and each of the tested predictions at forward muon angle and low Q2, indicating a missing suppression of the cross section in current neutrino-nucleus scattering models.
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