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Implications of Solar and Atmospheric Neutrinos  [PDF]
Paul Langacker
Physics , 1998, DOI: 10.1016/S0920-5632(99)00424-7
Abstract: The importance of non-zero neutrino mass as a probe of particle physics, astrophysics, and cosmology is emphasized. The present status and future prospects for the solar and atmospheric neutrinos are reviewed, and the implications for neutrino mass and mixing in 2, 3, and 4-neutrino schemes are discussed. The possibilities for significant mixing between ordinary and light sterile neutrinos are described.
Light Sterile Neutrinos: Status and Perspectives  [PDF]
Carlo Giunti
Physics , 2015,
Abstract: 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.
Sterile neutrinos
Kusenko, Alexander
High Energy Physics - Phenomenology , 2007, DOI: 10.1063/1.2751940
Abstract: Neutrino masses are usually described by adding to the Standard Model some SU(2)-singlet fermions that have the Yukawa couplings, as well as some Majorana mass terms. The number of such fields and the scales of their Majorana masses are not known. Several independent observations point to the possibility that some of these singlets may have masses well below the electroweak scale. A sterile neutrino with mass of a few keV can account for cosmological dark matter. The same particle would be emitted anisotropically from a cooling neutron star born in a supernova explosion. This anisotropy can be large enough to explain the observed velocities of pulsars. A lighter sterile neutrino, with mass of the order of eV, is implied by the LSND results; it can have profound implications for cosmology. We review the physics of sterile neutrinos and the roles they may play in astrophysics and cosmology.
Light Sterile Neutrinos: Models and Phenomenology  [PDF]
James Barry,Werner Rodejohann,He Zhang
Physics , 2011, DOI: 10.1007/JHEP07(2011)091
Abstract: Motivated by recent hints in particle physics and cosmology, we study the realization of eV-scale sterile neutrinos within both the seesaw mechanism and flavor symmetry theories. We show that light sterile neutrinos can rather easily be accommodated in the popular A_4 flavor symmetry models. The exact tri-bimaximal mixing pattern is perturbed due to active-sterile mixing, which we discuss in detail for one example. In addition, we find an interesting extension of the type I seesaw, which can provide a natural origin for eV-scale sterile neutrinos as well as visible admixtures between sterile and active neutrinos. We also show that the presence of sterile neutrinos would significantly change the observables in neutrino experiments, specifically the oscillation probabilities in short-baseline experiments and the effective mass in neutrino-less double beta decay. The latter can prove particularly helpful to strengthen the case for eV-scale sterile neutrinos.
Heavy neutrinos in particle physics and cosmology  [PDF]
Marco Drewes
Physics , 2015,
Abstract: Neutrinos are the only particles in the Standard Model of particle physics that have only been observed with left handed chirality to date. If right handed neutrinos exist, they would not only explain the observed neutrino oscillations, but could also be responsible for several phenomena in cosmology, including the baryon asymmetry of the universe, dark matter and dark radiation. A crucial parameter in this context is their Majorana mass, which in principle could lie anywhere between the eV scale and GUT scale. The implications for experiments and cosmology strongly depend on the choice of the mass scale. We review recent progress in the phenomenology of right handed neutrinos with different masses, focusing on scenarios in which the mass is at least a keV. We emphasise the possibility to discover heavy neutrinos that are responsible for the baryon asymmetry of the universe via low scale leptogenesis in near future experiments, such as LHC, BELLE II, SHiP, FCC-ee or CEPC.
Particle Physics with High Energy Neutrinos  [PDF]
T. K. Gaisser,F. Halzen,T. Stanev
Physics , 1994, DOI: 10.1016/0370-1573(95)00003-Y
Abstract: The topic of this review is the particle astrophysics of high energy neutrinos. High energy is defined as $E_{\nu} > 100$~MeV. Main topics include: -- atmospheric neutrinos and muons from $\pi$, $K$ and charm decay. They probe uncharted territory in neutrino oscillations and constitute both the background and calibration of high energy neutrino telescopes, -- sources of high energy neutrino beams: the galactic plane, the sun, X-ray binaries, supernova remnants and interactions of extra-galactic cosmic rays with background photons, -- an extensive review of the mechanisms by which active galaxies may produce high energy particle beams, -- high energy neutrino signatures of cold dark matter and, -- a brief review of detection techniques (water and ice Cherenkov detectors, surface detectors, radio- and acoustic detectors, horizontal airshower arrays) and the instruments under construction.
Evidence and Search for Sterile Neutrinos at Accelerators  [PDF]
W. C. Louis
Advances in High Energy Physics , 2013, DOI: 10.1155/2013/439532
Abstract: The LSND short-baseline neutrino experiment has published evidence for antineutrino oscillations at a mass scale of ~1?eV2. The MiniBooNE experiment, designed to test this evidence for oscillations at an order of magnitude higher neutrino energy and distance, observes excesses of events in both neutrino mode and antineutrino mode. While the MiniBooNE neutrino excess has a neutrino energy spectrum that is softer than expected from LSND, the MiniBooNE antineutrino excess is consistent with neutrino oscillations and with the LSND oscillation signal. When combined with oscillation measurements at the solar and atmospheric mass scales, assuming that the LSND and MiniBooNE signals are due to neutrino oscillations, these experiments imply the existence of more than three neutrino mass states and, therefore, one or more sterile neutrinos. Such sterile neutrinos, if proven to exist, would have a big impact on particle physics, nuclear physics, and astrophysics and would contribute to the dark matter of the universe. Future experiments under construction or proposed at Fermilab, ORNL, CERN, and in Japan will provide a definitive test of short-baseline neutrino oscillations and will have the capability of proving the existence of sterile neutrinos. 1. Introduction Neutrino oscillations have been clearly observed at the solar mass scale of ? and the atmospheric mass scale of [1]. However, evidence for neutrino oscillations at the ? mass scale has also been given by the LSND [2–6] and MiniBooNE [7–9] experiments. If the signals reported by LSND and MiniBooNE are indeed due to neutrino oscillations, then there is a problem with the three-neutrino paradigm, because it is not possible to explain oscillations at the three different mass scales with only three types of neutrinos. In order to solve this problem, additional “sterile” neutrinos have been proposed [10–14]. Other explanations include, for example, Lorentz violation [15, 16] and sterile neutrino decay [17, 18]. These additional neutrinos would need to be sterile to the weak interaction due to measurements of the width of the boson, which determine that there are three and only three active neutrinos [19]. The evidence for neutrino oscillations from LSND and MiniBooNE will be discussed in the following sections, followed by a discussion of global fits to the world data and future experiments, which will have the capability of proving whether short-baseline neutrino oscillations at the ~1? mass scale and light, sterile neutrinos exist in nature. 2. The LSND Experiment The LSND experiment [20] was designed to
On the physics of massive neutrinos  [PDF]
K. Zuber
Physics , 1998, DOI: 10.1016/S0370-1573(98)00033-7
Abstract: Massive neutrinos open up the possibility for a variety of new physical phenomena. Among them are oscillations and double beta decay. Furthermore they influence several fields from particle physics to cosmology. In this article the concept of massive neutrinos is given and the current status of experimental research is extensively reviewed. This includes astrophysical studies of solar, supernova and very high energy neutrinos. Future perspectives are also outlined.
The role of sterile neutrinos in cosmology and astrophysics  [PDF]
Alexey Boyarsky,Oleg Ruchayskiy,Mikhail Shaposhnikov
Physics , 2008, DOI: 10.1146/annurev.nucl.010909.083654
Abstract: We present a comprehensive overview of an extension of the Standard Model that contains three right-handed (sterile) neutrinos with masses below the electroweak scale [the Neutrino Minimal Standard Model, (nuMSM)]. We consider the history of the Universe from the inflationary era through today and demonstrate that most of the observed phenomena beyond the Standard Model can be explained within the framework of this model. We review the mechanism of baryon asymmetry of the Universe in the nuMSM and discuss a dark matter candidate that can be warm or cold and satisfies all existing constraints. From the viewpoint of particle physics the model provides an explanation for neutrino flavor oscillations. Verification of the nuMSM is possible with existing experimental techniques.
Sterile neutrinos?  [PDF]
S. M. Bilenky,C. Giunti
Physics , 1999,
Abstract: The notion of sterile neutrinos is discussed. The schemes of mixing of four massive neutrinos, which imply the existence of sterile neutrinos, are briefly considered. Several model independent methods that allow to reveal possible transitions of solar neutrinos into sterile states are presented.
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