This Letter reports a 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. Data from \(\nu_{\mu}(\bar{\nu}_{\mu})\rightarrow\nu_{\mu}(\bar{\nu}_{\mu})\) and \(\nu_{\mu}(\bar{\nu}_{\mu})\rightarrow\nu_{e}(\bar{\nu}_{e})\) oscillation channels are used to measure the effect of the NSI parameters \(\varepsilon_{e\mu}\) and \(\varepsilon_{e\tau}\). With 90% C.L. the magnitudes of the NSI couplings are constrained to be \(|\varepsilon_{e\mu}| \, \lesssim 0.3\) and \(|\varepsilon_{e\tau}| \, \lesssim 0.4\). A degeneracy at \(|\varepsilon_{e\tau}| \, \approx 1.8\) is reported, and we observe that the presence of NSI limits sensitivity to the standard CP phase \(\delta_{\tiny\text{CP}}\).
NOvA is a long-baseline neutrino oscillation experiment that measures oscillations in charged-current \(\nu_{\mu} \rightarrow \nu_{\mu}\) (disappearance) and \(\nu_{\mu} \rightarrow \nu_{e}\) ...(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 Phys. Rev. D 106, 032004 (2022) 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 \(\theta_{13}\) and the Jarlskog invariant. We use these results to quantify the strength of our inferences about CP violation, as well as to examine the effects of constraints from short-baseline measurements of \(\theta_{13}\) using antineutrinos from nuclear reactors when making NOvA measurements of \(\theta_{23}\). Our long-baseline measurement of \(\theta_{13}\) is also shown to be consistent with the reactor measurements, supporting the general applicability and robustness of the PMNS framework for neutrino oscillations.
We report cross-section measurements of the final-state muon kinematics for \numu charged-current interactions in the NOvA near detector using an accumulated 8.09\(\times10^{20}\) protons-on-target ...(POT) 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, \(E_\nu\), and square of the four-momentum transfer, \(Q^2\). We compare the results to inclusive cross-section predictions from various neutrino event generators via \(\chi^2\) 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 \(Q^2\), indicating a missing suppression of the cross section in current neutrino-nucleus scattering models.
Measuring observables to constrain models using maximum-likelihood estimation is fundamental to many physics experiments. The Profiled Feldman-Cousins method described here is a potential solution to ...common challenges faced in constructing accurate confidence intervals: small datasets, bounded parameters, and the need to properly handle nuisance parameters. This method achieves more accurate frequentist coverage than other methods in use, and is generally applicable to the problem of parameter estimation in neutrino oscillations and similar measurements. We describe an implementation of this method in the context of the NOvA experiment.
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