ABSTRACT The hypothesis that high-energy cosmic neutrinos are power law distributed is critically analyzed. We propose a model with two components that better explains the observations. The ...extragalactic component of the high-energy neutrino flux has a canonical spectrum while the galactic component has a spectrum; both of them are significant. This model has several implications, which can be tested by IceCube and ANTARES over the next several years. Moreover, the existence of a diffuse component, close to the Galactic plane and that yields (20-30)% of IceCube's events, is interesting for the future km3 neutrino telescopes located in the Northern Hemisphere and for gamma-ray telescopes aiming to measure events up to a few 100 TeV from the southern sky.
•For neutrino astronomy, the knowledge of the rate of core collapse supernovae is of essential importance.•We use the best available information to update its study and to obtain the state-of-the-art ...value: R = 1.63 ± 0.46/century.•We discuss the consistency of the results and point out the critical aspects in this inference.
Several large neutrino telescopes, operating at various sites around the world, have as their main objective the first detection of neutrinos emitted by a gravitational collapse in the Milky Way. The success of these observation programs depends on the rate of supernova core collapse in the Milky Way, R. In this work, standard statistical techniques are used to combine several independent results. Their consistency is discussed and the most critical input data are identified. The inference on R is further tested and refined by including direct information on the occurrence rate of gravitational collapse events in the Milky Way and in the Local Group, obtained from neutrino telescopes and electromagnetic surveys. A conservative treatment of the errors yields a combined rate R=1.63±0.46 (100 yr)−1; the corresponding time between core collapse supernova events turns out to be T=61−14+24 yr. The importance to update the analysis of the stellar birthrate method is emphasized.
The standard model of elementary interactions has long qualified as a theory of matter, in which the postulated conservation laws (one baryonic and three leptonic) acquire theoretical meaning. ...However, recent observations of lepton number violations—neutrino oscillations—demonstrate its incompleteness. We discuss why these considerations suggest the correctness of Ettore Majorana’s ideas on the nature of neutrino mass and add further interest to the search for an ultra-rare nuclear process in which two particles of matter (electrons) are created, commonly called neutrinoless double beta decay. The approach of the discussion is mainly historical, and its character is introductory. Some technical considerations, which highlight the usefulness of Majorana’s representation of gamma matrices, are presented in the appendix.
The discovery of neutrino masses through the observation of oscillations boosted the importance of neutrinoless double beta decay ( 0 ν β β ). In this paper, we review the main features of this ...process, underlining its key role from both the experimental and theoretical point of view. In particular, we contextualize the 0 ν β β in the panorama of lepton number violating processes, also assessing some possible particle physics mechanisms mediating the process. Since the 0 ν β β existence is correlated with neutrino masses, we also review the state of the art of the theoretical understanding of neutrino masses. In the final part, the status of current 0 ν β β experiments is presented and the prospects for the future hunt for 0 ν β β are discussed. Also, experimental data coming from cosmological surveys are considered and their impact on 0 ν β β expectations is examined.
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We discuss as accurately as possible the cross section of quasi-elastic scattering of electron (anti-)neutrinos on nucleons, also known as inverse beta decay in the case of antineutrinos. ...We focus on the moderate energy range from a few MeV up to hundreds of MeV, which includes neutrinos from reactors and supernovae. We assess the uncertainty on the cross section, which is relevant to experimental advances and increasingly large statistical samples. We estimate the effects of second-class currents, showing that they are small and negligible for current applications.
The natural parameterization of vacuum oscillations in three neutrino flavors is studied. Compact and exact relations of its three parameters with the ordinary three mixing angles and CP-violating ...phase are obtained. Its usefulness is illustrated by considering various applications: the study of the flavor ratio and of its uncertainties, the comparison of expectations and observations in the flavor triangle, and the intensity of the signal due to Glashow resonance. The results in the literature are easily reproduced and in particular the recently obtained agreement of the observations of IceCube with the hypothesis of cosmic neutrino oscillations is confirmed. It is argued that a Gaussian treatment of the errors appropriately describes the effects of the uncertainties on the neutrino oscillation parameters.
This writeup is a review of current hot topics on solar neutrinos. It is based on a talk at the conference “Neutrinos: the quest for a new physics scale”, held at the CERN on March 2017, where the ...Organizers entrusted me with a discussion of the provocative question “whether solar neutrino physics is over”. Rather than providing a straight (negative) answer, in view of an audience consisting mostly of colleagues working in theoretical particle physics, I deemed it more useful providing a description of what is the current activity of the physicists working in solar neutrinos, leaving the listener free of forming his/her own opinion apropos.
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