Neutrino mass ordering determination through combined analysis with JUNO and KM3NeT/ORCA

The neutrino mass ordering (NMO) is one of the fundamental questions in neutrino physics. KM3NeT/ORCA and JUNO are two neutrino oscillation experiments both aiming at measuring the NMO with different approaches: ORCA with atmospheric neutrinos traversing the Earth and JUNO with reactor neutrinos. This contribution presents the potential of determining the NMO through a combined analysis of JUNO and ORCA data. In a joint fit, the NMO sensitivity is enhanced beyond the simple sum of the sensitivities of each experiment due to the tension between the respective Δm 31 2 best fit values obtained when the wrong ordering is assumed, together with good constraints on this parameter measurement by both experiments. From this analysis, we expect the true NMO to be determined with 5σ significance after 1–2 years of data taking by both experiments for the current global best-fit values of the oscillation parameters, while maximally 6 years will be needed for any other parameter set.

Deuteron disintegration by reactor antineutrinos

The existence of a new interaction involving the electron neutrino and the nucleons, which has received a convincing confirmation through a good agreement between the theoretical and experimental results concerning all observable processes with solar neutrinos, should also inevitably manifest itself in the deuteron disintegration by the neutral currents of reactor antineutrinos. The special attention is drawn to the problem of finding the neutron registration efficiency, discussed in the preparation of the experiment at the Sudbury Neutrino Observatory and in a number of special studies. Lessons are noted that can be learned from three long-standing experiments on the deuteron disintegration by reactor neutrinos.

What Neutrino Reaction Has a Large Cross-Section?

All reactions that are currently used to detect neutrinos are endothermic (more precisely, endo-energy). They occur at the expense of the energy of neutrino that initiates them. These reactions are characterized by a very small cross-section, which is close in magnitude to the 10−20 barn. Beta decay is an exo-thermal (more precisely, exo-energetic) reaction. Currently, it seems that the entire physical community believes that the beta decay phenomenon occurs completely by accident. However, recent experiments with reactor neutrinos [1, 2] have shown that their flux makes an additional contribution to the beta decay rate. Since beta decay is an exo-energetic reaction, neutrinos catalyze beta-active nuclei without losing own energy (or with a small loss of it). The cross-section of this process is much larger than the cross-section of the endo-energetic interaction of neutrinos with matter. Experimental measurements show that the cross section of reactor neutrinos with 63Ni nuclei is close to 1 barn.

Search for eV Neutrino Sterile: Status of STEREO Experiment

Reactor neutrinos have played a key role in understanding neutrino physics since their discovery. The so-called reactor-anti-neutrino-anomaly RAA, a ∼6.5% deficit of the mean observed neutrino flux compared to the prediction appeared recently. This anomaly could be interpreted by the existence of a fourth, sterile, neutrino and this hypothesis is currently being tested by the very short baseline experiment STEREO. The latter is installed at very short distance (9-11m) from the compact core of the ILL research reactor in Grenoble-France and collecting data since November 2016. The ILL core is highly enriched in 235U and releases a nominal thermal power of 58.3 MW. The geometry of the STEREO detector, segmented into six identical cells filled with Gd-loaded liquid scintillator, is designed for a direct test of a new oscillation pattern in the L/E range around 1 m/MeV, relevant for the RAA. First published results of STEREO have demonstrated the mitigation of the background induced by the reactor and the cosmic-rays and a good energy response. The data taking is now in progress with very stable conditions favorable for an improved accuracy. We will present an overview of the experiment and an update of the sterile neutrino analysis. A refined prediction of the neutrino spectrum emitted by the ILL reactor is also presented.

Constraints on Neutrino Electric Millicharge from Experiments of Elastic Neutrino-Electron Interaction and Future Experimental Proposals Involving Coherent Elastic Neutrino-Nucleus Scattering

In several extensions of the Standard Model of Particle Physics (SMPP), the neutrinos acquire electromagnetic properties such as the electric millicharge. Theoretical and experimental bounds have been reported in the literature for this parameter. In this work, we first carried out a statistical analysis by using data from reactor neutrino experiments, which include elastic neutrino-electron scattering (ENES) processes, in order to obtain both individual and combined limits on the neutrino electric millicharge (NEM). Then, we performed a similar calculation to show an estimate of the sensitivity of future experiments of reactor neutrinos to the NEM, by involving coherent elastic neutrino-nucleus scattering (CENNS). In the first case, the constraints achieved from the combination of several experiments are − 1.1 × 1 0 − 12 e < q ν < 9.3 × 1 0 − 13 e (90% C.L.), and in the second scenario, we obtained the bounds − 1.8 × 1 0 − 14 e < q ν < 1.8 × 1 0 − 14 e (90% C.L.). As we will show here, these combined analyses of different experimental data can lead to stronger constraints than those based on individual analysis, where CENNS interactions would stand out as an important alternative to improve the current limits on NEM.

On the Free Neutron Decay with Neutrino(s) Interactions

This paper proposes a mechanism for the decay of free neutron with interactions with neutrino(s). A mathematical framework is developed using canonical ensemble framework for the interactions. Probability distribution of neutron discrete energy states has been derived which is a function of neutrino-zeta – a macroscopic property of neutrinos. Consequently, a relationship between neutron decay constant and probability of neutron beta decay is provided, assuming linear proportionality. Furthermore, qualitative explanation of neutron lifetime puzzle, where discrepancy in lifetime measurements based on measurement method (Bottle vs Beam), is related to neutrino microscopic cross-sections. In addition, inverse beta-decay reaction of proton and beta-negative and beta-positive reaction of radionuclides have been analyzed using the proposed mechanism. The probabilities of beta-negative and beta-positive reactions in nature are qualitatively in agreement with the proposed mechanism. Lastly, way to test the mechanism experimentally with reactor neutrinos and neutrino beams has been presented.