Search for eV neutrino sterile: Status of STEREO experiment
Ilham El Atmani
备注：
6 pages, 10 figures, to appear in the Proceedings of the INPC 2019 Conference, submitted to JPCS ( referenced as: I El Atmani 2019 J. Phys.: Conf. Ser. Submitted )
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 ${}^{235}\textrm{U}$ 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.
The STEREO experiment is designed to test the hypothesis of light sterile neutrinos being the cause of the Reactor Antineutrino Anomaly. It measures the antineutrino energy spectrum from the compact core of the ILL research reactor in six identical detector cells covering baselines between 9 and 11 m. Results from 119 days of reactor turned on and 211 days of reactor turned off are reported. Using a direct comparison between neutrino interaction rates of all cells, independent of any flux prediction, we find compatibility with the null oscillation hypothesis. The best fit point of the Reactor …
Search for a light sterile neutrino is currently a hot topic of neutrino physics, arising from the so-called gallium and reactor anomalies, in which a deficit of neutrinos was observed with respect to expectations. Such anomalies could be explained by short distance oscillations towards a sterile state, with $Δ\mathrm{m}^2\sim$1\,eV$^2$. The STEREO detector has been designed to track the electron anti-neutrino energy spectrum distortion from 3 to 8\,MeV due to such a new $L/E$ oscillation, and should therefore confirm or reject the light sterile neutrino hypothesis. Electron anti-neutrinos pro…
Recent studies have shown that there are discrepancies between observations and the theoretical predictions in some neutrino experiments at short distances. In the so-called "Reactor Antineutrino Anomaly" and in the "Gallium Anomaly", these differences from the expectations are at the $\sim$3 $σ$ level in both cases. Oscillations into a light sterile neutrino state ($Δm^{2} \sim 1eV^{2}$) could account for the deficits in observed rates. The STEREO experiment has been conceived to confirm or reject the sterile neutrino hypothesis. It will search for an oscillation pattern at short baselines (9…
In the recent years, major milestones in neutrino physics were accomplished at nuclear reactors: the smallest neutrino mixing angle $θ_{13}$ was determined with high precision and the emitted antineutrino spectrum was measured at unprecedented resolution. However, two anomalies, the first one related to the absolute flux and the second one to the spectral shape, have yet to be solved. The flux anomaly is known as the Reactor Antineutrino Anomaly and could be caused by the existence of a light sterile neutrino participating in the neutrino oscillation phenomenon. Introducing a sterile state imp…
In the recent years, major milestones in neutrino physics were accomplished at nuclear reactors: the smallest neutrino mixing angle $θ_{13}$ was determined with high precision and the emitted antineutrino spectrum was measured at unprecedented resolution. However, two anomalies, the first one related to the absolute flux and the second one to the spectral shape, have yet to be solved. The flux anomaly is known as the Reactor Antineutrino Anomaly and could be caused by the existence of a light sterile neutrino eigenstate participating in the neutrino oscillation phenomenon. Introducing a steril…
Reactor neutrinos have been an intense field of investigation for the last decade. Two anomalies are discussed in this document. First, a status of the sterile neutrino searches by STEREO, PROSPECT and DANSS is presented. The best-fit parameters of active-to-sterile oscillations from the Reactor Antineutrino Anomaly are strongly rejected by these experiments. Second, the analyses of the shape anomaly ("5 MeV bump") by STEREO and PROSPECT, both using a virtually pure-$^{235}$U neutrino flux, are detailed. Results show a significant excess of events at 5-6 MeV and indicate that the bump observed…
The STEREO experiment is a very short baseline reactor antineutrino experiment. It is designed to test the hypothesis of light sterile neutrinos being the cause of a deficit of the observed antineutrino interaction rate at short baselines with respect to the predicted rate, known as the reactor antineutrino anomaly. The STEREO experiment measures the antineutrino energy spectrum in six identical detector cells covering baselines between 9 and 11 m from the compact core of the ILL research reactor. In this article, results from 179 days of reactor turned on and 235 days of reactor turned off ar…
At the 17th J-PARC PAC, which was held on September 2013, we proposed the sterile neutrino search at J-PARC MLF. After reviewing the proposal, PAC recommended to have a background measurement at the detector's candidate site location in their report to investigate whether the background rates can be manageable for the real experiment or not. Therefore, we have performed the background measurements (MLF; 2013BU1301 test experiment) during the summer of 2014, also following the 18th J-PARC PAC recommendations, and the measurements results are described here.
We propose a new experiment to search for a sterile neutrino in a few keV mass range at the "Troitsk nu-mass" facility. The expected signature corresponds to a kink in the electron energy spectrum in tritium beta-decay. The new goal compared to our previous experiment will be precision spectrum measurements well below end point. The experimental installation consists of a windowless gaseous tritium source and a high resolution electromagnetic spectrometer. We estimate that the current bounds on the sterile neutrino mixing parameter can be improved by an order of magnitude in the mass range und…
The reactor antineutrino anomaly might be explained by the oscillation of reactor antineutrinos toward a sterile neutrino of eV mass. In order to explore this hypothesis, the STEREO experiment measures the antineutrino energy spectrum in six different detector cells covering baselines between 9 and 11 m from the compact core of the ILL research reactor. In this Letter, results from 66 days of reactor turned on and 138 days of reactor turned off are reported. A novel method to extract the antineutrino rates has been developed based on the distribution of the pulse shape discrimination parameter…
On April 2015, the J-PARC E56 (JSNS2: J-PARC Sterile Neutrino Search using neutrinos from J-PARC Spallation Neutron Source) experiment officially obtained stage-1 approval from J-PARC. We have since started to perform liquid scintillator R&D for improving energy resolution and fast neutron rejection. Also, we are studying Avalanche Photo-Diodes (SiPM) inside the liquid scintillator. In addition to the R&D work, a background measurement for the proton beam bunch timing using a small liquid scintillator volume was planned, and the safety discussions for the measurement have been done. This repor…
A number of anomalous results in short-baseline oscillation may hint at the existence of one or more light sterile neutrino states in the eV mass range and have triggered a wave of new experimental efforts to search for a definite signature of oscillations between active and sterile neutrino states. The present paper aims to provide a comprehensive review on the status of light sterile neutrino searches in mid-2019: we discuss not only the basic experimental approaches and sensitivities of reactor, source, atmospheric, and accelerator neutrino oscillation experiments but also the complementary…
There are $\sim3σ$ or more evidence of eV-scale sterile neutrinos from several different measurements. Many dedicated experiments are (being) created and (will) take data to confirm or refute the eV-scale sterile neutrinos. In this talk, a mini review is presented on current experimental efforts and status on sterile neutrino search, especially using reactor and accelerator neutrinos.
The indications in favor of the existence of light sterile neutrinos at the eV scale found in short-baseline neutrino oscillation experiments is reviewed. The future perspectives of short-baseline neutrino oscillation experiments and the connections with beta-decay measurements of the neutrino masses and with neutrinoless double-beta decay experiments are discussed.
The JSNS2 (J-PARC E56) experiment aims to search for sterile neutrinos at the J-PARC Materials and Life Sciences Experimental Facility (MLF).After the submission of a proposal to the J-PARC PAC, stage-1 approval was granted to the JSNS2 experiment. The approval followed a series of background measurements which were performed in 2014. Subsequent for stage-1 approval, the JSNS2 collaboration has made continuous efforts to write a Technical Design Report (TDR).This TDR will include two major items as discussed in the previous status report for the 20th J-PARC PAC: (1) A realistic detector locati…
Two anomalies at nuclear reactors, one related to the absolute antineutrino flux, one related to the antineutrino spectral shape, have drawn special attention to the field of reactor neutrino physics during the past decade. Numerous experimental efforts have been launched to investigate the reliability of flux models and to explore whether sterile neutrino oscillations are at the base of the experimental findings. This review aims to provide an overview on the status of experimental searches at reactors for sterile neutrino oscillations and measurements of the antineutrino spectral shape in mi…
The reactor antineutrino energy spectra and flux were reevaluated during the preparation of the recent experiments devoted to the measurement of $θ_{13}$. Consequently some discrepancies between data and the theoretical predictions in reactor antineutrino experiments at short distances were observed when using the new predicted flux and spectra. This problem has been called the Reactor Antineutrino Anomaly (RAA), which together with the gallium anomaly, both show discrepancies with respect to the expectations at the $\sim$ 3 $σ$ level. Oscillations into a light sterile neutrino state ($Δm^{2} …
A number of short baseline neutrino oscillation experiments have observed an anomalous excess of neutrinos in the low energy range. This may hint towards the existence of additional neutrino mass splittings. If true, additional sterile (non-interacting) neutrino states above the current 3 neutrino model would be required. On the other hand, many parameters of the allowed space are limited by experiments that have seen no anomaly. We will introduce models which accommodate these additional neutrinos, and then discuss our work towards fitting these models to the available global high $Δm^{2}$ os…
In the past decades, short baseline neutrino oscillation studies around experimental or commercial reactor cores have revealed two anomalies. The first one is linked to the absolute flux and the second one to the spectral shape. The first anomaly, called Reactor Antineutrino Anomaly (RAA), could be explained by the introduction of a new oscillation of antineutrinos towards a sterile state of the eV mass. The \stereo detector has been taking data since the end of 2016 at 10~m from the core of the Institut Laue-Langevin research reactor, Grenoble, France. The separation of its Target volume alon…
Most of the neutrino oscillation results can be explained by the three-neutrino paradigm. However several anomalies in short baseline oscillation data could be interpreted by invoking a hypothetical fourth neutrino, separated from the three standard neutrinos by a squared mass difference of more than 0.1 eV$^2$. This new neutrino, often called sterile, would not feel standard model interactions but mix with the others. Such a scenario calling for new physics beyond the standard model has to be either ruled out or confirmed with new data. After a brief review of the anomalous oscillation result…
The JSNS$^2$ (J-PARC E56) experiment aims to search for a sterile neutrino at the J-PARC Materials and Life Sciences Experimental Facility (MLF). After the submission of a proposal to the J-PARC PAC, Stage-1 approval was granted to the JSNS$^2$ experiment on April 2015.This approval followed a series of background measurements which were performed in 2014. Recently, funding (the grant-in-aid for scientific research (S)) in Japan for building one 25~ton fiducial volume detector module was approved for the experiment. Therefore, we aim to start the experiment with one detector in JFY2018-2019. W…
The $\sim 3σ$ discrepancy between the predicted and observed reactor anti-neutrino flux, known as the reactor anti-neutrino anomaly, continues to intrigue. The recent discovery of an unexpected bump in the reactor anti-neutrino spectrum, as well as indications that the flux deficit is different for different fission isotopes seems to disfavour the explanation of the anomaly in terms of sterile neutrino oscillations. We critically review this conclusion in view of all available data on electron (anti)neutrino disappearance. We find that the sterile neutrino hypothesis cannot be rejected based o…
I describe two new searches for sterile neutrino oscillations from the MINOS and Daya Bay experiments. MINOS looked for evidence through muon neutrino disappearance with data collected from the NuMI neutrino beam. Daya Bay searched for evidence through electron antineutrino disappearance using data collected from nuclear reactors. I explain how the MINOS and Daya Bay searches were combined to produce constraints on the same phase space as LSND and MiniBooNE. Finally, I present the status of the sterile neutrino search using data from MINOS+.
Several anomalies observed in short-baseline neutrino experiments indicate that the standard 3-flavor framework may be incomplete and point towards the existence of light sterile neutrinos. Here, we present a concise review of the status of the neutrino oscillations within the 3+1 scheme, which is a minimal extension of the standard 3-flavor framework with one sterile neutrino species. We emphasize the potential role of LBL experiments in the searches of CP violation connected to sterile neutrinos and their complementarity with the SBL experiments.
Sterile neutrinos may be an important extension to the standard model, and could both hold the key to understanding neutrino mass and mixing as well as play an important role in leptogenesis. In many models, the sterile neutrinos could be light and accessible to current and near term experiments. The MiniBooNE experiment is set up to explore these possibilities in the $Δm^{2}$ region from 0.3 to a few eV$^{2}$ where the LSND experiment has reported a $\barν_{e}$ appearance signal. This report will outline some of these extensions, give the status and prospects for the MiniBooNE experiment, and…
The OPERA experiment at the CNGS beam has observed muon to tau neutrino oscillations in the atmospheric sector. Based on this result new limits on the mixing parameters of a massive sterile neutrino may be set. Preliminary results of the analysis done in the 3+1 neutrino framework are here presented. An update of the search for sterile neutrinos in the $ν_μ \rightarrow ν_e$ channel is also given. The status of the searches for sterile neutrinos performed at other Long--Baseline experiments (MINOS at NuMI beam and SuperK with the atmospheric flux) is also briefly recalled. Finally, some persona…
OPERA is a long-baseline experiment at the Gran Sasso laboratory (LNGS) designed to search for $ν_μ\rightarrow ν_τ$ oscillations in appearance mode. OPERA took data from 2008 to 2012 with the CNGS neutrino beam from CERN. The data analysis is ongoing, with the goal of establishing $ν_τ$ appearance with high significance and improving the sensitivity to the sterile neutrino search in the $ν_μ$ $\rightarrow$ $ν_e$ appearance channel. Current results will be presented and perspectives discussed.
We review sterile neutrinos as possible Dark Matter candidates. After a short summary on the role of neutrinos in cosmology and particle physics, we give a comprehensive overview of the current status of the research on sterile neutrino Dark Matter. First we discuss the motivation and limits obtained through astrophysical observations. Second, we review different mechanisms of how sterile neutrino Dark Matter could have been produced in the early universe. Finally, we outline a selection of future laboratory searches for keV-scale sterile neutrinos, highlighting their experimental challenges a…
The STEREO experiment is a very short baseline reactor antineutrino experiment aiming at testing the hypothesis of light sterile neutrinos as an explanation of the deficit of the observed neutrino interaction rate with respect to the predicted rate, known as the Reactor Antineutrino Anomaly. The detector center is located 10 m away from the compact, highly $^{235}$U enriched core of the research nuclear reactor of the Institut Laue Langevin in Grenoble, France. This paper describes the STEREO site, the detector components and associated shielding designed to suppress the external sources of ba…
We present new results of measurements of reactor antineutrino flux and spectrum dependence on the distance in the range 6-12 meters from the center of the reactor core at SM-3 reactor (Dimitrovgrad, Russia). Additional measurements were carried out and set of data to perform statistical analysis was almost doubled since the previous report. Using all collected data we performed the model independent analysis on the oscillation parameters $Δm^2_{14}$ and $\sin^2(2θ_{14})$. The method of coherent summation of results of measurements allows us to directly observe the effect of oscillations. We o…
The KATRIN experiment, presently under construction in Karlsruhe, Germany, will improve on previous laboratory limits on the neutrino mass by a factor of ten. KATRIN will use a high-activity, gaseous T2 source and a very high-resolution spectrometer to measure the shape of the high-energy tail of the tritium-decay beta spectrum. The shape measurement will also be sensitive to new physics, including sterile neutrinos and Lorentz violation. This report summarizes recent progress in the experiment.
We describe a new detector, called NuLat, to study electron anti-neutrinos a few meters from a nuclear reactor, and search for anomalous neutrino oscillations. Such oscillations could be caused by sterile neutrinos, and might explain the "Reactor Antineutrino Anomaly". NuLat, is made possible by a natural synergy between the miniTimeCube and mini-LENS programs described in this paper. It features a "Raghavan Optical Lattice" (ROL) consisting of 3375 boron or $^6$Li loaded plastic scintillator cubical cells 6.3\,cm (2.500") on a side. Cell boundaries have a 0.127\,mm (0.005") air gap, resulting…
A next-generation neutrino telescope infrastructure, the Kilometer Cube Neutrino Telescope KM3NeT, is currently under construction in the Mediterranean Sea. Its low energy configuration ORCA is optimised for the detection of atmospheric neutrinos with energies above ~1 GeV. The main goal of the ORCA detector is the precise measurement of atmospheric neutrino oscillation parameters and the determination of the neutrino mass ordering. The detector is also sensitive to a variety of other physics topics, such as dark matter, non-standard interactions and sterile neutrinos. An overview is presented…
The correspondence of the results obtained in the Neutrino-4 experiment with the results of the NEOS, DANSS, STEREO, PROSPECT experiments at reactors, the MiniBooNE, LSND, MicroBoone experiments at accelerators, the IceCube experiment and the BEST experiment with a ${}^{51}\text{Cr}$ neutrino source is analyzed. The agreement between the results of the Neutrino-4 experiment, the BEST experiment and the gallium anomaly on mixing angel is discussed. The disagreement between the results of the above-mentioned direct experiments with the results of the reactor anomaly, as well as with the limitati…
Neutrinos, being the only fermions in the Standard Model of Particle Physics that do not possess electromagnetic or color charges, have the unique opportunity to communicate with fermions outside the Standard Model through mass mixing. Such Standard Model-singlet fermions are generally referred to as "sterile neutrinos''. In this review article, we discuss the theoretical and experimental motivation for sterile neutrinos, as well as their phenomenological consequences. With the benefit of hindsight in 2020, we point out potentially viable and interesting ideas. We focus in particular on steril…
Different extensions of the standard model of particle physics, such as braneworld or mirror matter models, predict the existence of a neutron sterile state, possibly as a dark matter candidate. This Letter reports a new experimental constraint on the probability $p$ for neutron conversion into a hidden neutron, set by the STEREO experiment at the high flux reactor of the Institut Laue-Langevin. The limit is $p<3.1\times 10^{-11}$ at $95 \%$ C.L. improving the previous limit by a factor 13. This result demonstrates that short-baseline neutrino experiments can be used as competitive passing-thr…
We review the status of searches for sterile neutrinos in the $\sim 1$ eV range, with an emphasis on the latest results from short baseline oscillation experiments and how they fit within sterile neutrino oscillation models. We present global fit results to a three-active-flavor plus one-sterile-flavor model (3+1), where we find an improvement of $Δχ^2=35$ for 3 additional parameters compared to a model with no sterile neutrino. This is a 5$σ$ improvement, indicating that an effect that is like that of a sterile neutrino is highly preferred by the data. However we note that separate fits to th…
The current status of the phenomenology of short-baseline neutrino oscillations induced by light sterile neutrinos in the framework of 3+1 mixing is reviewed.
The possibility of the validation of the 3+1 neutrino model is considered in the context of the new result of the Neutrino-4 experiment, the direct observation of the oscillation effect at parameter region $Δm_{14}^2=(7.3 \pm 0.13_{stat} \pm 1.16_{syst})\text{eV}^2$ and $\sin^2(2θ_{14}) = 0.36 \pm 0.12_{stat} (2.9σ)$, also using LSND anomaly, MiniBooNE anomaly, reactor antineutrino anomaly, and gallium anomaly observed in experiments with radioactive sources GALLEX/GNO and SAGE. We analyze agreement of the neutrino parameter values obtained in the Neutrino-4 experiment with the results of othe…
This article reports the status of a $ν_μ \to ν_{e}$ oscillation search in MiniBooNE (Booster Neutrino Experiment) experiment. If an appearance signal is observed, it will imply Physics Beyond the Standard Model such as the existence of light sterile neutrino.
This review demonstrates the unique role of the neutrino by discussing in detail the physics of and with neutrinos. We deal with neutrino sources, neutrino oscillations, absolute masses, interactions, the possible existence of sterile neutrinos, and theoretical implications. In addition, synergies of neutrino physics with other research fields are found, and requirements to continue successful neutrino physics in the future, in terms of technological developments and adequate infrastructures, are stressed.
We comment on the claimed observation [arXiv:arXiv:2005.05301] of sterile neutrino oscillations by the Neutrino-4 collaboration. Such a claim, which requires the existence of a new fundamental particle, demands a level of rigor commensurate with its impact. The burden lies with the Neutrino-4 collaboration to provide the information necessary to prove the validity of their claim to the community. In this note, we describe aspects of both the data and analysis method that might lead to an oscillation signature arising from a null experiment and describe additional information needed from the Ne…
MicroBooNE is a neutrino experiment based at Fermilab which consists of a liquid argon time-projection chamber in the Booster Neutrino Beam (BNB). The experiment aims to investigate the excess of electron-neutrino-like events seen by the MiniBooNE experiment, also located in the BNB, which is potential evidence for new non-Standard Model physics such as sterile neutrinos. I discuss the status of a search for low-energy electron-neutrino interactions within the MicroBooNE detector. This analysis features a hybrid approach of traditional reconstruction methods along with the use of convolutional…
We study the interplay of neutrino oscillation and invisible decay in atmospheric and long-baseline neutrinos experiments. We perform a global analysis of the full atmospheric data from Super-Kamiokande together with long-baseline K2K and MINOS in these scenarios. We find that the admixture of nu_mu -> nu_tau oscillations with parameters Delta_m32^2 = 2.6e-3 eV^2 and theta_23 ~ 34 degrees plus decay of the heavy neutrino, nu_3, with lifetime of the order tau_3/m_3 ~ 2.6e-12 s/eV provides a reasonable fit to atmospheric neutrinos, although this solution becomes more disfavored (dropping to the …
We present an updated global analysis of two-flavor MSW solutions to the solar neutrino problem in terms of conversions of nu_e into active or sterile neutrinos. We perform a fit to the full data set corresponding to the 825-day Super-Kamiokande data sample as well as to Chlorine, GALLEX and SAGE experiments. We use all measured total event rates as well as Super-Kamiokande data on the zenith angle dependence, energy spectrum and seasonal variation of the events. For conversions into active neutrinos we find that, although the data on the total event rates favours the Small Mixing Angle (SMA) …
We present an update of our analysis of short-baseline neutrino oscillation data in the framework of 3+1 neutrino mixing taking into account the recent update of MiniBooNE antineutrino data and the recent results of the MINOS search for nu_mu disappearance into sterile neutrinos (the more complicated 3+2 neutrino mixing is not needed since the CP-violating difference between MiniBooNE neutrino and antineutrino data has diminished). The results of our fits of short-baseline neutrino oscillation data including the MiniBooNE low-energy anomaly (now present both in the neutrino and antineutrino da…
We study the status of the reactor antineutrino anomaly in light of recent reactor flux models obtained with the conversion and summation methods. We present a new improved calculation of the IBD yields of the standard Huber-Mueller (HM) model and those of the new models. We show that the reactor rates and the fuel evolution data are consistent with the predictions of the Kurchatov Institute (KI) conversion model and with those of the Estienne-Fallot (EF) summation model, leading to a plausible robust demise of the reactor antineutrino anomaly. We show that the results of several goodness of f…
The Standard Solar Model (BP04) predicts a total 8B neutrino flux that is 17.2% larger than measured in the salt phase of the SNO detector (and if it were significant it will indicate oscillation to sterile neutrinos). Hence it is important to examine in details uncertainties (and values) of inputs to the SSM. Currently, the largest fractional uncertainty is due to the new evaluation of the surface composition of the sun. We examine the nuclear input on the formation of solar 8B [S17(0)] and demonstrate that it is still quite uncertain due to ill known slope of the measured astrophysical cross…
The long awaited experimental results from MiniBooNE have recently been announced. This experiment tests whether neutrino oscillations can occur at a higher mass squared difference $\sim1 {eV}^2$ compared to well established observations of solar and atmospheric neutrinos. The LSND experiment has previously claimed to have observed neutrino oscillations at $Δm^2 \sim 1 {eV}^2$, however the results being controversial, required an independent confirmation. The MiniBooNE results settle this controversy by observing null oscillations at the said mass squared difference. These results have strong …
This article summarises a talk given at the 2014 Palermo workshop on Astrophysics. It covers a short review on the neutrino physics status and the potential physics opportunities of future experiments. During the last year our knowledge on the neutrino oscillation parameter $\sin^2θ_{13}$ improved dramatically, and the large value opened the way to oscillation experiments sensitive to possible CP-violation. The first high-energetic neutrinos in the TeV range were detected in the IceCube experiment, while the Planck collaboration set further limits on the number of active neutrinos from cosmolo…
Measurements of various features of the fluxes of atmospheric and solar neutrinos have provided evidence for neutrino oscillations and therefore for neutrino masses and mixing. We review the phenomenology of neutrino oscillations in vacuum and in matter. We present the existing evidence from solar and atmospheric neutrinos as well as the results from laboratory searches, including the final status of the LSND experiment. We describe the theoretical inputs that are used to interpret the experimental results in terms of neutrino oscillations. We derive the allowed ranges for the mass and mixing …
