We study visible neutrino decay at the reactor neutrino experiments KamLAND and, JUNO. Assuming the Majoron model of neutrino decay, we obtain constraints on the couplings between Majoron and neutrino as well as on the lifetime/mass of the most massive neutrino state i.e., $τ_{3} / m_{3}$ or $τ_{2} / m_{2}$, respectively, for the normal or the inverted mass orderings. We obtain the constraints on the lifetime $τ_{2} / m_{2} \geq 1.4 \times 10^{-9}~\rm{s/eV}$ in the inverted mass ordering for both KamLAND and JUNO at 90% CL. In the normal ordering in which the bound can be obtained for JUNO only, the constraint is milder than the inverted ordering case, $τ_{3} / m_{3} \geq 1.0 \times 10^{-10}~\rm{s/eV}$ at 90% CL. We find that the dependence of lightest neutrino mass ($=m_{\rm{lightest}}$), $m_1 (m_3)$ for the normal (inverted) mass ordering, on the constraints for the different types of couplings (scalar or pseudo-scalar) is rather strong, but the $m_{\rm{lightest}}$ dependence on the lifetime/mass bound is only modest.
The IsoDAR antineutrino source, which produces a flux from 8Li isotope decay at rest, when paired with the proposed JUNO (Jiangmen Underground Neutrino Observatory) detector, has unprecedented sensitivity to anti-nu_e disappearance for oscillations at high Delta m^2. Assuming CPT invariance, the sensitive region for anti-nu_e disappearance can be used to restrict the allowed parameter space of an anti-nu_mu to anti-nu_e appearance signal. The 5 sigma sensitivity of this experiment covers the entire anti-nu_mu to anti-nu_e allowed parameter space from a combined fit to short-baseline experiment…
If ultra-light dark matter (ULDM) exists and couples to neutrinos, the neutrino oscillation probability might be significantly altered by a parametric resonance. This resonance can occur if the typical frequency of neutrino flavor-oscillations $Δm^2/(2E)$, where $Δm^2$ is the mass-squared difference of the neutrinos and $E$ is the neutrino energy, matches the oscillation frequency of the ULDM field, determined by its mass, $m_ϕ$. The resonance could lead to observable effects even if the ULDM coupling is very small, and even if its typical oscillation period, given by $τ_ϕ=2π/m_ϕ$, is much sho…
The Super-light Sterile Neutrino Scenario (SSNS) has been proposed in the literature to explain the suppression of the upturn in the low energy solar data. In this scenario, the mass splitting between the new mass eigenstate, $ν_0$ and the standard $ν_1$ is of order of $Δm_{01}^2\sim 10^{-5}$ eV$^2$. Reactor neutrino experiments with baseline larger than $\sim$20 km can help us to probe this scenario. We study the potential of upcoming JUNO and RENO-50 reactor experiments for discovering the superlight sterile neutrino or constraining its mixing parameters. We study the dependence of sensitivi…
Measurements of the solar neutrino mass-squared difference from KamLAND and solar neutrino data are somewhat discrepant, perhaps due to nonstandard neutrino interactions in matter. We show that the zenith angle distribution of solar neutrinos at Hyper-Kamiokande and the energy spectrum of reactor antineutrinos at JUNO can conclusively confirm the discrepancy and detect new neutrino interactions.
The flux of geoneutrinos at any point on the Earth is a function of the abundance and distribution of radioactive elements within our planet. This flux has been successfully detected by the 1-kt KamLAND and 0.3-kt Borexino detectors with these measurements being limited by their low statistics. The planned 20-kt JUNO detector will provide an exciting opportunity to obtain a high statistics measurement, which will provide data to address several questions of geological importance. This paper presents the JUNO detector design concept, the expected geo-neutrino signal and corresponding background…
The presence of a super-light sterile neutrino can lead to a dip in the survival probability of solar neutrinos, and explain the suppression of the upturn in the low energy solar neutrino data. In this work, we systematically study the survival probabilities in the 3+1 framework by taking into account of the non-adiabatic transitions and the coherence effect. We obtain an analytic equation that can predict the position of the dip. We also place constraints on the parameter space of sterile neutrinos by using the latest Borexino and KamLAND data. We find that the low and high energy neutrino da…
A high-statistics measurement of the neutrinos from a galactic core-collapse supernova is extremely important for understanding the explosion mechanism, and studying the intrinsic properties of neutrinos themselves. In this paper, we explore the possibility to constrain the absolute scale of neutrino masses $m^{}_ν$ via the detection of galactic supernova neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO) with a 20 kiloton liquid-scintillator detector. In assumption of a nearly-degenerate neutrino mass spectrum and a normal mass ordering, the upper bound on the absolute neutrino…
Constraining the Neutrino Mixing Matrix via Single-Sector Charged-Lepton Rotations in the JUNO Precision Era
INFN Sezione di Roma（意大利国家核物理研究所罗马分部）；Instituto de Física Corpuscular (CSIC-Universitat de València)（粒子物理研究所（西班牙高等科研理事会-瓦伦西亚大学））；Departament de Física Teòrica, Universitat de València（瓦伦西亚大学理论物理系）；Dipartimento di Matematica e Fisica, Universitá di Roma Tre（罗马第三大学数学与物理系）
As an attractive candidate for dark matter, the primordial black holes (PBHs) in the mass range ($10^{15} \sim 10^{16}$)$\mathrm{g}$ could be detected via their Hawking radiation, including neutrinos and antineutrinos of three flavors. In this paper, we investigate the possibility to constrain the PBH as dark matter by measuring (anti)neutrino signals at the large liquid-scintillator detector of Jiangmen Underground Neutrino Observatory (JUNO). Among six available detection channels, the inverse beta decay $\overlineν^{}_e + p \to e^+ + n$ is shown to be most sensitive to the fraction $f^{}_{\…
We explore the impact of the data from the KamLAND experiment in constraining neutrino mass and mixing angles involved in solar neutrino oscillations. In particular we discuss the precision with which we can determine the the mass squared difference $Δm^2_{solar}$ and the mixing angle $θ_{solar}$ from combined solar and KamLAND data. We show that the precision with which $Δm^_{solar}$ can be determined improves drastically with the KamLAND data but the sensitivity of KamLAND to the mixing angle is not as good. We study the effect of enhanced statistics in KamLAND as well as reduced systematics…
Models of neutrino mixing involving one or more sterile neutrinos have resurrected their importance in the light of recent cosmological data. In this case, reactor antineutrino experiments offer an ideal place to look for signatures of sterile neutrinos due to their impact on neutrino flavor transitions. In this work, we show that the high-precision data of the Daya Bay experi\-ment constrain the 3+1 neutrino scenario imposing upper bounds on the relevant active-sterile mixing angle $\sin^2 2 θ_{14} \lesssim 0.06$ at 3$σ$ confidence level for the mass-squared difference $Δm^2_{41}$ in the rang…
We consider the problem of determination of the neutrino mass ordering via precise study of the vacuum neutrino oscillations in the JUNO and other future medium baseline reactor neutrino experiments. We are proposing to resolve neutrino mass ordering by determination of the neutrino oscillation parameters from analysis of the data of the reactor experiments and comparison them with the oscillation parameters obtained from analysis of the solar and KamLAND experiments.
We review neutrino oscillation physics, including the determination of mass splittings and mixings from current solar, atmospheric, reactor and accelerator neutrino data. A brief discussion is given of cosmological and astrophysical implications. Non-oscillation phenomena such as neutrinoless double beta decay would, if discovered, probe the absolute scale of neutrino mass and also reveal their Majorana nature. Non-oscillation descriptions in terms of spin-flavor precession (SFP) and non-standard neutrino interactions (NSI) currently provide an excellent fit of the solar data. However they are…
When the next galactic core-collapse supernova occurs, we must be ready to obtain as much information as possible. Although many present and future detectors are well equipped to detect $\overlineν_{\mathrm{e}}$ and $ν_x$ neutrinos, the detection of the $ν_{\mathrm{e}}$ species presents the biggest challenges. We assess the impact that a 1 ktonne lead-based detector, such as HALO-1kT, can have in constraining electron neutrino time-integrated fluxes. The study involves the detector taken alone as well as when combined with massive $\overlineν_{\mathrm{e}}$-sensitive detectors such as Super-Kam…
We re-analyze the compatibility of the claimed observation of neutrinoless double beta decay ($0νββ$) in $^{76}$Ge with the new limits on the half-life of $^{136}$Xe from EXO-200 and KamLAND-Zen. Including recent calculations of the nuclear matrix elements (NMEs), we show that while the claim in $^{76}$Ge is still compatible with the individual limits from $^{136}$Xe, it is inconsistent with the KamLAND-Zen+EXO-200 combined limit for all but one NME calculations. After imposing the most stringent upper limit on the sum of light neutrino masses from Planck, we find that the canonical light neut…
Constraining Ultra-Light Vector Bosons via Solar Neutrino Oscillations: The Gauged $L_μ- L_τ$ Model and Prospects for JUNO and XLZD
Centro de Astrofísica e Gravitação - CENTRA, Departamento de Física, Instituto Superior Técnico - IST, Universidade de Lisboa - UL（里斯本大学技术研究所物理系天体物理学与引力中心）
We present a reanalysis of nonstandard neutrino-down-quark interactions of electron and tau neutrinos using solar, reactor and accelerator data. In addition updating the analysis by including new solar data from SNO phase III and Borexino, as well as new KamLAND data and solar fluxes, a key role is played in our analysis by the combination of these results with the CHARM data. The latter allows us to better constrain the axial and axial-vector electron and tau-neutrino nonstandard interaction parameters characterizing the deviations from the Standard Model predictions.
However the allowed range of $θ_{\odot}$ ($θ_{12}$) did not change much with the inclusion of the KamLAND results. In this paper we probe if future data from KamLAND can increase the accuracy of the allowed range in $θ_{\odot}$ and conclude that even after 3 kton-year of statistics and most optimistic error estimates, KamLAND {\it may} find it hard to significantly improve the bounds on the mixing angle obtained from the solar neutrino data. We discuss the $θ_{12}$ sensitivity of the survival probabilities in matter (vacuum) as is relevant for the solar (KamLAND) experiments. We find that the …
We discuss the impact of different solar neutrino data on the spin-flavor-precession (SFP) mechanism of neutrino conversion. We find that, although detailed solar rates and spectra allow the SFP solution as a sub-leading effect, the recent KamLAND constraint on the solar antineutrino flux places stronger constraints to this mechanism. Moreover, we show that for the case of random magnetic fields inside the Sun, one obtains a more stringent constraint on the neutrino magnetic moment down to the level of μ_ν\lsim few \times 10^{-12}μ_B, similar to bounds obtained from star cooling.
We use solar neutrino data to derive stringent bounds on Majorana neutrino transition moments (TMs). Such moments, if present, would contribute to the neutrino-electron scattering cross section and hence alter the signal observed in Super-Kamiokande. Using the latest solar neutrino data, combined with the results of the reactor experiment KamLAND, we perform a simultaneous fit of the oscillation parameters and TMs. Furthermore, we include data from the reactor experiments Rovno, TEXONO and MUNU in our analysis, improving significantly the current constraints on TMs. A comparison with previous …
The rise-up in boron neutrino spectrum at low energies has been studied within the framework of `pure LMA' scenario. Indirect bounds on the spectral `upturn' have been obtained from the available solar neutrino data. These bounds have been used to demonstrate the efficacy of the precision measurements of the `upturn' for further constraining the neutrino parameter space allowed by SNO salt phase data. The sterile neutrino flux has been constrained in the light of the recent 766.3 Ty KamLAND spectral data.
In this paper we use solar neutrino data to derive stringent bounds on Majorana neutrino transition moments (TMs). Should such be present, they would contribute to the neutrino--electron scattering cross section and hence alter the signal observed in Super-Kamiokande. Motivated by the growing robustness of the LMA-MSW solution of the solar neutrino problem indicated by recent data, and also by the prospects of its possible confirmation at KamLAND, we assume the validity of this solution, and we constrain neutrino TMs by using the latest global solar neutrino data. We find that all elements of …
The eV-scale sterile neutrino has been proposed to explain some anomalous results in experiments, \textit{such as} the deficit of reactor neutrino fluxes and the excess of $\barν_μ\to\barν_e$ in LSND. This hypothesis can be tested by future core-collapse supernova neutrino detection independently since the active-sterile mixing scheme affects the flavor conversion of neutrinos inside the supernova. In this work, we compute the predicted supernova neutrino events in future detectors -- DUNE, Hyper-K, and JUNO -- for neutrinos emitted during the neutronization burst phase when the luminosity of …
We analyze the impact of recent solar, atmospheric and reactor data in the determination of the neutrino oscillation parameters, taking into account that both the solar nu_e and the atmospheric nu_mu may convert to a mixture of active and sterile neutrinos. We use the most recent global solar neutrino data, including the 1496-day Super-K neutrino data sample, and we investigate in detail the impact of the SNO neutral current, spectral and day/night data by performing also an analysis using only the charged current rate from SNO. The implications of the first 145.1 days of KamLAND data on the d…
We have studied dark matter (DM) phenomenology, neutrinoless double beta decay (NDBD) and realized low scale leptogenesis in an extension of Standard Model(SM) with three neutral fermions, a scalar doublet and a dark sector incorporating a singlet scalar and a Dirac singlet fermion. A generic model based on $A_4\times Z_4$ flavor symmetry including five flavons is used to explain both normal and inverted hierarchy mass patterns of neutrino and also to accommodate the dark matter mass. In this extension of the $ν$2HDM, the effective neutrino mass observed in $0νββ$ is well within the experiment…
The Jiangmen Underground Neutrino Observatory~(JUNO) features a 20~kt multi-purpose underground liquid scintillator sphere as its main detector. Some of JUNO's features make it an excellent experiment for $^8$B solar neutrino measurements, such as its low-energy threshold, its high energy resolution compared to water Cherenkov detectors, and its much large target mass compared to previous liquid scintillator detectors. In this paper we present a comprehensive assessment of JUNO's potential for detecting $^8$B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2~MeV…
