Future Neutrino Oscillation Experiments Research Articles

Measurements of the inclusive neutrino and antineutrino charged current cross sections in MINERvA using the low- ν flux method

The total cross sections are important ingredients for the current and future neutrino oscillation experiments. We present measurements of the total charged-current neutrino and antineutrino cross sections on scintillator (CH) in the NuMI low-energy beamline using an {\em in situ} prediction of the shape of the flux as a function of neutrino energy from 2--50 GeV. This flux prediction takes advantage of the fact that neutrino and antineutrino interactions with low nuclear recoil energy ($\nu$) have a nearly constant cross section as a function of incident neutrino energy. This measurement is the lowest energy application of the low-$\nu$ flux technique, the first time it has been used in the NuMI antineutrino beam configuration, and demonstrates that the technique is applicable to future neutrino beams operating at multi-GeV energies. The cross section measurements presented are the most precise measurements to date below 5 GeV.

Extended scaling and residual flavor symmetry in the neutrino Majorana mass matrix

The residual symmetry approach, along with a complex extension for some flavor invariance, is a powerful tool to uncover the flavor structure of the $3\times3$ neutrino Majorana mass matrix $M_\nu$ towards gaining insights into neutrino mixing. We utilize this to propose a complex extension of the real scaling ansatz for $M_\nu$ which was introduced some years ago. Unlike the latter, our proposal allows a nonzero mass for each of the three light neutrinos as well as a nonvanishing $\theta_{13}$. A major result of this scheme is that leptonic Dirac CP-violation must be maximal while atmospheric neutrino mixing need not be exactly maximal. Moreover, each of the two allowed Majorana phases, to be probed by the search for nuclear $0\nu \beta\beta$ decay, has to be at one of its two CP-conserving values. There are other interesting consequences such as the allowed occurrence of a normal mass ordering which is not favored by the real scaling ansatz. Our predictions will be tested in ongoing and future neutrino oscillation experiments at T2K, NO$\nu$A and DUNE.

A combined view of sterile-neutrino constraints from CMB and neutrino oscillation measurements

We perform a comparative analysis of constraints on sterile neutrinos from the Planck experiment and from current and future neutrino oscillation experiments (MINOS, IceCube, SBN). For the first time, we express the Planck constraints on $N_{\rm eff}$ and $m_{\rm eff}^{\rm sterile}$ from the Cosmic Microwave Background in the parameter space used by oscillation experiments using both mass-squared differences and mixing angles. In a model with a single sterile neutrino species and using standard assumptions, we find that the Planck data and the oscillation experiments measuring muon-neutrino disappearance have similar sensitivity.

Neutrino mass, dark matter and anomalous magnetic moment of muon in a U 1 L μ − L τ $$ \mathrm{U}{(1)}_L{{}_{{}_{\mu}}}_{-}{{}_L}_{{}_{\tau }} $$ model

The observation of neutrino masses, mixing and the existence of dark matter are amongst the most important signatures of physics beyond the Standard Model (SM). In this paper, we propose to extend the SM by a local $L_\mu - L_\tau$ gauge symmetry, two additional complex scalars and three right-handed neutrinos. The $L_\mu - L_\tau$ gauge symmetry is broken spontaneously when one of the scalars acquires a vacuum expectation value. The $L_\mu - L_\tau$ gauge symmetry is known to be anomaly free and can explain the beyond SM measurement of the anomalous muon $({\rm g-2})$ through additional contribution arising from the extra $Z_{\mu\tau}$ mediated diagram. Small neutrino masses are explained naturally through the Type-I seesaw mechanism, while the mixing angles are predicted to be in their observed ranges due to the broken $L_\mu-L_\tau$ symmetry. The second complex scalar is shown to be stable and becomes the dark matter candidate in our model. We show that while the $Z_{\mu\tau}$ portal is ineffective for the parameters needed to explain the anomalous muon $({\rm g-2})$ data, the correct dark matter relic abundance can easily be obtained from annihilation through the Higgs portal. Annihilation of the scalar dark matter in our model can also explain the Galactic Centre gamma ray excess observed by Fermi-LAT. We show the predictions of our model for future direct detection experiments and neutrino oscillation experiments.

Direct extraction of nuclear effects in quasielastic scattering on carbon

Nuclear effects on neutrino reactions are expected to be a significant complication in current and future neutrino oscillation experiments seeking precision measurements of neutrino flavor transitions. Calculations of these nuclear effects are hampered by a lack of experimental data comparing neutrino reactions on free nucleons to neutrino reactions on nuclei. We present results from a novel technique that compares neutrino and antineutrino charged current quasielastic scattering on hydrocarbons to extract a cross section ratio of antineutrino charged current elastic reactions on free protons to charged current quasielastic reactions on the protons bound in a carbon nucleus. This measurement of nuclear effects is compared to models.

Non-standard interactions in propagation at the Deep Underground Neutrino Experiment

We study the sensitivity of current and future long-baseline neutrino oscillation experiments to the effects of dimension six operators affecting neutrino propagation through Earth, commonly referred to as Non-Standard Interactions (NSI). All relevant parameters entering the oscillation probabilities (standard and non-standard) are considered at once, in order to take into account possible cancellations and degeneracies between them. We find that the Deep Underground Neutrino Experiment will significantly improve over current constraints for most NSI parameters. Most notably, it will be able to rule out the so-called LMA-dark solution, still compatible with current oscillation data, and will be sensitive to off-diagonal NSI parameters at the level of $\varepsilon \sim \mathcal{O}(0.05 - 0.5)$. We also identify two degeneracies among standard and non-standard parameters, which could be partially resolved by combining T2HK and DUNE data.

Identification of Nuclear Effects in Neutrino-Carbon Interactions at Low Three-Momentum Transfer.

Two different nuclear-medium effects are isolated using a low three-momentum transfer subsample of neutrino-carbon scattering data from the MINERvA neutrino experiment. The observed hadronic energy in charged-current ν_{μ} interactions is combined with muon kinematics to permit separation of the quasielastic and Δ(1232) resonance processes. First, we observe a small cross section at very low energy transfer that matches the expected screening effect of long-range nucleon correlations. Second, additions to the event rate in the kinematic region between the quasielastic and Δ resonance processes are needed to describe the data. The data in this kinematic region also have an enhanced population of multiproton final states. Contributions predicted for scattering from a nucleon pair have both properties; the model tested in this analysis is a significant improvement but does not fully describe the data. We present the results as a double-differential cross section to enable further investigation of nuclear models. Improved description of the effects of the nuclear environment are required by current and future neutrino oscillation experiments.

Generalized μ–τ reflection symmetry and leptonic CP violation

We propose a generalized μ–τ reflection symmetry to constrain the lepton flavor mixing parameters. We obtain a new correlation between the atmospheric mixing angle θ23 and the “Dirac” CP violation phase δCP. Only in a specific limit our proposed CP transformation reduces to standard μ–τ reflection, for which θ23 and δCP are both maximal. The “Majorana” phases are predicted to lie at their CP-conserving values with important implications for the neutrinoless double beta decay rates. We also study the phenomenological implications of our scheme for present and future neutrino oscillation experiments including T2K, NOνA and DUNE.

Constraint on neutrino decay with medium-baseline reactor neutrino oscillation experiments

The experimental bound on lifetime of ν 3, the neutrino mass eigenstate with the smallest ν e component, is much weaker than those of ν 1 and ν 2 by many orders of magnitude to which the astrophysical constraints apply. We argue that the future reactor neutrino oscillation experiments with medium-baseline (∼50 km), such as JUNO or RENO-50, has the best chance of placing the most stringent constraint on ν3 lifetime among all neutrino experiments which utilize the artificial source neutrinos. Assuming decay into invisible states, we show by a detailed χ 2 analysis that the ν 3 lifetime divided by its mass, τ 3 /m 3, can be constrained to be τ 3 /m 3 > 7.5 (5.5) × 10−11 s/eV at 95% (99%) C.L. by 100 kt·years exposure by JUNO. It may be further improved to the level comparable to the atmospheric neutrino bound by its longer run. We also discuss to what extent ν 3 decay affects mass-ordering determination and precision measurements of the mixing parameters.

Comparison of the calorimetric and kinematic methods of neutrino energy reconstruction in disappearance experiments

To be able to achieve their physics goals, future neutrino-oscillation experiments will need to reconstruct the neutrino energy with very high accuracy. In this work, we analyze how the energy reconstruction may be affected by realistic detection capabilities, such as energy resolutions, efficiencies, and thresholds. This allows us to estimate how well the detector performance needs to be determined a priori in order to avoid a sizable bias in the measurement of the relevant oscillation parameters. We compare the kinematic and calorimetric methods of energy reconstruction in the context of two muon-neutrino disappearance experiments operating in different energy regimes. For the calorimetric reconstruction method, we find that the detector performance has to be estimated with a ~10% accuracy to avoid a significant bias in the extracted oscillation parameters. On the other hand, in the case of kinematic energy reconstruction, we observe that the results exhibit less sensitivity to an overestimation of the detector capabilities.

Predicting lepton flavor mixing from Δ(48) and generalized CP symmetries**Supported by National Natural Science Foundation of China (11275188, 11179007, 11135009)

We propose to understand the mixing angles and CP-violating phases from the Δ(48) family symmetry combined with the generalized CP symmetry. A model-independent analysis is performed by scanning all the possible symmetry breaking chains. We find a new mixing pattern with only one free parameter, excellent agreement with the observed mixing angles can be achieved and all the CP-violating phases are predicted to take nontrivial values. This mixing pattern is testable in the near future neutrino oscillation and neutrinoless double-beta decay experiments. Finally, a flavor model is constructed to realize this mixing pattern.

Study on the Neutrino Oscillation with a Next Generation Medium-Baseline Reactor Experiment

For over fifty years, reactor experiments have played an important role in neutrino physics, in both discoveries and precision measurements. One of the methods to verify the existence of neutrino is the observation of neutrino oscillation phenomena. Electron antineutrinos emitted from a reactor provide the measurement of the small mixing angleθ13, providing rich programs of neutrino properties, detector development, nuclear monitoring, and application. Using reactor neutrinos, future reactor neutrino experiments, more precise measurements ofθ12, Δm122, and mass hierarchy will be explored. The precise measurement ofθ13would be crucial for measuring the CP violation parameters at accelerators. Therefore, reactor neutrino physics will assist in the complete understanding of the fundamental nature and implications of neutrino masses and mixing. In this paper, we investigated several characteristics of RENO-50, which is a future medium-baseline reactor neutrino oscillation experiment, by using the GloBES simulation package.

Physics Potential of Long-Baseline Experiments

The discovery of neutrino mixing and oscillations over the past decade provides firm evidence for new physics beyond the Standard Model. Recently,θ13has been determined to be moderately large, quite close to its previous upper bound. This represents a significant milestone in establishing the three-flavor oscillation picture of neutrinos. It has opened up exciting prospects for current and future long-baseline neutrino oscillation experiments towards addressing the remaining fundamental questions, in particular the type of the neutrino mass hierarchy and the possible presence of a CP-violating phase. Another recent and crucial development is the indication of non-maximal 2-3 mixing angle, causing the octant ambiguity ofθ23. In this paper, I will review the phenomenology of long-baseline neutrino oscillations with a special emphasis on sub-leading three-flavor effects, which will play a crucial role in resolving these unknowns. First, I will give a brief description of neutrino oscillation phenomenon. Then, I will discuss our present global understanding of the neutrino mass-mixing parameters and will identify the major unknowns in this sector. After that, I will present the physics reach of current generation long-baseline experiments. Finally, I will conclude with a discussion on the physics capabilities of accelerator-driven possible future long-baseline precision oscillation facilities.

Neutrino mass textures with one vanishing minor and two equal cofactors

In this paper, we carry out a numerical and systematic analysis of the neutrino mass textures, which contain one vanishing minor and equality between two cofactors. Among 60 logically possible textures, only eight of them are excluded for both the normal and inverted hierarchy by the current experimental data at 3σ level. We also demonstrate that the future long-baseline neutrino oscillation experiments, especially for the measurement of the θ 23 mixing angle, will play an important role in the model selection. The phenomenological implications from neutrinoless double-beta decay and the cosmology observation are also examined. A discussion of the flavor symmetry realization of the textures is also given.

Light and superlight sterile neutrinos in the minimal radiative inverse seesaw model

We explore the possibility of light and superlight sterile neutrinos in the recently proposed Minimal Radiative Inverse Seesaw extension of the Standard Model for neutrino masses, in which all existing neutrino data can be explained. In particular, we discuss two benchmark scenarios with one of the three sterile neutrino states in the keV-range, having very small mixing with the active neutrinos to account for the Dark Matter in the Universe, while (i) the other two light sterile neutrino states could be in the eV-range, possessing a nonzero mixing with the active states as required to explain the LSND+MiniBooNE+reactor neutrino data, or (ii) one of the light sterile states is in the eV-range, whereas the second one could be superlight and almost mass-degenerate with the solar neutrinos. Such superlight sterile neutrinos could give rise to potentially observable effects in future neutrino oscillation experiments and may also offer a possible explanation for the extra radiation observed in the Universe.

Systematic uncertainties in long-baseline neutrino oscillations for largeθ13

We study the physics potential of future long-baseline neutrino oscillation experiments at large $\theta_{13}$, focusing especially on systematic uncertainties. We discuss superbeams, \bbeams, and neutrino factories, and for the first time compare these experiments on an equal footing with respect to systematic errors. We explicitly simulate near detectors for all experiments, we use the same implementation of systematic uncertainties for all experiments, and we fully correlate the uncertainties among detectors, oscillation channels, and beam polarizations as appropriate. As our primary performance indicator, we use the achievable precision in the measurement of the CP violating phase $\deltacp$. We find that a neutrino factory is the only instrument that can measure $\deltacp$ with a precision similar to that of its quark sector counterpart. All neutrino beams operating at peak energies $\gtrsim 2$ GeV are quite robust with respect to systematic uncertainties, whereas especially \bbeams and \thk suffer from large cross section uncertainties in the quasi-elastic regime, combined with their inability to measure the appearance signal cross sections at the near detector. A noteworthy exception is the combination of a $\gamma=100$ \bbeam with an \spl-based superbeam, in which all relevant cross sections can be measured in a self-consistent way. This provides a performance, second only to the neutrino factory. For other superbeam experiments such as \lbno and the setups studied in the context of the \lbne reconfiguration effort, statistics turns out to be the bottleneck. In almost all cases, the near detector is not critical to control systematics since the combined fit of appearance and disappearance data already constrains the impact of systematics to be small provided that the three active flavor oscillation framework is valid.

Elastic scattering with the MINERνA experiment

The Main Injector Experiment ν-A (MINERνA) located at Fermi National Laboratory will measure neutrino cross sections, nuclear effects from a broad range of nuclear targets and a variety of other neutrino interactions. Neutrino elastic scattering will be one of the first focuses of the MINERA collaboration; these measurements will be an important input to current and future neutrino oscillation experiments. Results of the charged current quasi-elastic channel exposure in anti-neutrino NuMI running are presented. Future elastic scattering results, both charged current and neutral current, in anti-neutrino and neutrino exposures are also discussed.

Neutrino cross section measurements @ SciBooNE

We report measurements of cross sections of neutrinos of 0.7 GeV average energy scattering off a carbon target cross sections with by the SciBooNE experiment at Fermilab. These measurements are important inputs for current and future accelerator-based neutrino oscillation experiments in the interpretation of neutrino oscillation signals.

Radiative corrections to the leptonic DiracCP-violating phase

Since the smallest leptonic mixing angle ${\ensuremath{\theta}}_{13}$ has been measured to be relatively large, it is quite promising to constrain or determine the leptonic Dirac $CP$-violating phase $\ensuremath{\delta}$ in future neutrino oscillation experiments. Given some typical values of $\ensuremath{\delta}=\ensuremath{\pi}/2$, $\ensuremath{\pi}$, and $3\ensuremath{\pi}/2$ at the low energy scale, as well as current experimental results of the other neutrino parameters, we perform a systematic study of radiative corrections to $\ensuremath{\delta}$ by using the one-loop renormalization group equations in the minimal supersymmetric standard model and the universal extra-dimensional model. It turns out that $\ensuremath{\delta}$ is rather stable against radiative corrections in both models, except for the minimal supersymmetric standard model with a very large value of $\mathrm{tan}\ensuremath{\beta}$. Both cases of Majorana and Dirac neutrinos are discussed. In addition, we use the preliminary indication of $\ensuremath{\delta}=({1.08}_{\ensuremath{-}0.31}^{+0.28})\ensuremath{\pi}$ or $\ensuremath{\delta}=({1.67}_{\ensuremath{-}0.77}^{+0.37})\ensuremath{\pi}$ from the latest global-fit analyses of data from neutrino oscillation experiments to illustrate how it will be modified by radiative corrections.

Precision on leptonic mixing parameters at future neutrino oscillation experiments

We perform a comparison of the different future neutrino oscillation experiments based on the achievable precision in the determination of the fundamental parameters theta_{13} and the CP phase, delta, assuming that theta_{13} is in the range indicated by the recent Daya Bay measurement. We study the non-trivial dependence of the error on delta on its true value. When matter effects are small, the largest error is found at the points where CP violation is maximal, and the smallest at the CP conserving points. The situation is different when matter effects are sizable. As a result of this effect, the comparison of the physics reach of different experiments on the basis of the CP discovery potential, as usually done, can be misleading. We have compared various proposed super-beam, beta-beam and neutrino factory setups on the basis of the relative precision of theta_{13} and the error on delta. Neutrino factories, both high-energy or low-energy, outperform alternative beam technologies. An ultimate precision on theta_{13} below 3% and an error on delta of < 7^{\circ} at 1 sigma (1 d.o.f.) can be obtained at a neutrino factory.