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Double- and single-differential cross sections for inclusive charged-current ${\nu }_{\mu }$-nucleus scattering are reported for the kinematic domain 0 to $2\mathrm{GeV}/c$in three-momentum transfer and 0 to 2 GeV in available energy, at a mean ${\nu }_{\mu }$energy of 1.86 GeV. The measurements are based on an estimated 995,760 ${\nu }_{\mu }$charged-current (CC) interactions in the scintillator medium of the NOvA Near Detector. The subdomain populated by 2-particle-2-hole (2p2h) reactions is identified by the cross section excess relative to predictions for ${\nu }_{\mu }$-nucleus scattering that are constrained by a data control sample. Models for 2-particle-2-hole processes are rated by ${\chi }^2$comparisons of the predicted-versus-measured ${\nu }_{\mu }$CC inclusive cross section over the full phase space and in the restricted subdomain. Shortfalls are observed in neutrino generator predictions obtained using the theory-based València and SuSAv2 2p2h models. Published by the American Physical Society2025 

Abstract Measuring observables to constrain models using maximum-likelihood estimation is fundamental to many physics experiments. Wilks' theorem provides a simple way to construct confidence intervals on model parameters, but it only applies under certain conditions. These conditions, such as nested hypotheses and unbounded parameters, are often violated in neutrino oscillation measurements and other experimental scenarios. Monte Carlo methods can address these issues, albeit at increased computational cost. In the presence of nuisance parameters, however, the best way to implement a Monte Carlo method is ambiguous. This paper documents the method selected by the NOvA experiment, the profile construction. It presents the toy studies that informed the choice of method, details of its implementation, and tests performed to validate it. It also includes some practical considerations which may be of use to others choosing to use the profile construction. 

Abstract This paper presents the expected sensitivity to the neutrino oscillation parameters of the Hyper-Kamiokande long-baseline program. The Hyper-Kamiokande experiment, currently under construction in Japan, will measure the oscillations of accelerator-produced neutrinos with thousands of selected events per sample: this corresponds to an increase of statistics of a factor 25–100 with respect to recent results from the currently-running long-baseline neutrino oscillation experiment in Japan, T2K. In the most favorable scenario we will achieve the discovery of Charge-Parity (CP) violation in neutrino oscillation at$$5\sigma $$ $5\sigma$C.L. in less than 3 years. With 10 years of data-taking, and assuming a neutrino : antineutrino beam running ratio of 1:3, a CP violation discovery at$$5\sigma $$ $5\sigma$C.L. is possible for more than 60% of the actual values of the CP-violating phase,$$\delta _{CP}.$$ ${\delta }_{\mathrm{CP}}.$Moreover, we will measure$$\delta _{CP}$$ ${\delta }_{\mathrm{CP}}$with a precision ranging from 20$$^{\circ },$$ $_{}^{\circ },$in the case of maximal CP violation, to 6$$^{\circ },$$ $_{}^{\circ },$in the case of CP conservation. We aim to achieve a 0.5% resolution on the$$\Delta m^2_{32}$$ $\Delta m_{32}^2$parameter, and a resolution between 3% and 0.5% on the$$\sin ^2\theta _{23}$$ ${sin}^2{\theta }_{23}$parameter, depending on its true value. These results are obtained by extending the analysis methods of T2K with dedicated tuning to take into account the Hyper-Kamiokande design: the larger far detector, the more powerful beam, the upgraded near detector ND280, and the planned additional Intermediate Water Cherenkov Detector. 

Abstract The landmark discovery that neutrinos have mass and can change type (or flavour) as they propagate—a process called neutrino oscillation^1–6—has opened up a rich array of theoretical and experimental questions being actively pursued today. Neutrino oscillation remains the most powerful experimental tool for addressing many of these questions, including whether neutrinos violate charge-parity (CP) symmetry, which has possible connections to the unexplained preponderance of matter over antimatter in the Universe^7–11. Oscillation measurements also probe the mass-squared differences between the different neutrino mass states (Δm²), whether there are two light states and a heavier one (normal ordering) or vice versa (inverted ordering), and the structure of neutrino mass and flavour mixing¹². Here we carry out the first joint analysis of datasets from NOvA¹³and T2K¹⁴, the two currently operating long-baseline neutrino oscillation experiments (hundreds of kilometres of neutrino travel distance), taking advantage of our complementary experimental designs and setting new constraints on several neutrino sector parameters. This analysis provides new precision on the$$\Delta {m}_{32}^{2}$$ $\Delta m_{32}^2$mass difference, finding$$2.4{3}_{-0.03}^{+0.04}\times 1{0}^{-3}\,{{\rm{eV}}}^{2}$$ $2.43_{-0.03}^{+0.04}\times 10^{-3}{\mathrm{eV}}^2$in the normal ordering and$$-2.4{8}_{-0.04}^{+0.03}\times 1{0}^{-3}\,{{\rm{eV}}}^{2}$$ $-2.48_{-0.04}^{+0.03}\times 10^{-3}{\mathrm{eV}}^2$in the inverted ordering, as well as a 3σinterval onδ_CPof [−1.38π, 0.30π] in the normal ordering and [−0.92π, −0.04π] in the inverted ordering. The data show no strong preference for either mass ordering, but notably, if inverted ordering were assumed true within the three-flavour mixing model, then our results would provide evidence of CP symmetry violation in the lepton sector. 

This Letter reports a search for charge-parity ( $CP$) symmetry violating nonstandard interactions (NSI) of neutrinos with matter using the NOvA Experiment, and examines their effects on the determination of the standard oscillation parameters. Data from ${\nu }_{\mu }\left({\overline{\nu }}_{\mu }\right)\to {\nu }_{\mu }\left({\overline{\nu }}_{\mu }\right)$and ${\nu }_{\mu }\left({\overline{\nu }}_{\mu }\right)\to {\nu }_e\left({\overline{\nu }}_e\right)$oscillation channels are used to measure the effect of the NSI parameters ${ϵ}_{e\mu }$and ${ϵ}_{e\tau }$. With 90% CL the magnitudes of the NSI couplings are constrained to be $\left|{ϵ}_{e\mu }\right|\lesssim 0.3$and $\left|{ϵ}_{e\tau }\right|\lesssim 0.4$. A degeneracy at $\left|{ϵ}_{e\tau }\right|\approx 1.8$is reported, and we observe that the presence of NSI limits sensitivity to the standard $CP$phase ${\delta }_{CP}$. Published by the American Physical Society2024 

NOvA is a long-baseline neutrino oscillation experiment that measures oscillations in charged-current ${\nu }_{\mu }\to {\nu }_{\mu }$(disappearance) and ${\nu }_{\mu }\to {\nu }_e$(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 [] 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 ${\theta }_{13}$, where we find $0.071\le {\sin }^{2}2{\theta }_{13}\le 0.107$, and the Jarlskog invariant, where we observe no significant preference for the $CP$-conserving value $J=0$over values favoring $CP$violation. We use these results 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 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 Society2024 

The Super-Kamiokande and T2K Collaborations present a joint measurement of neutrino oscillation parameters from their atmospheric and beam neutrino data. It uses a common interaction model for events overlapping in neutrino energy and correlated detector systematic uncertainties between the two datasets, which are found to be compatible. Using 3244.4 days of atmospheric data and a beam exposure of $19.7\left(16.3\right)\times {10}^{20}$protons on target in (anti)neutrino mode, the analysis finds a $1.9\sigma$exclusion of $CP$conservation (defined as $J_{CP}=0$) and a $1.2\sigma$exclusion of the inverted mass ordering. Published by the American Physical Society2025