skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Oscillation properties of active and sterile neutrinos and neutrino anomalies at short distances

Abstract

A generalized phenomenological (3 + 2 + 1) model featuring three active and three sterile neutrinos that is intended for calculating oscillation properties of neutrinos for the case of a normal active neutrino mass hierarchy and a large splitting between the mass of one sterile neutrino and the masses of the other two sterile neutrinos is considered. A new parametrization and a specific form of the general mixing matrix are proposed for active and sterile neutrinos with allowance for possible CP violation in the lepton sector, and test values are chosen for the neutrino masses and mixing parameters. The probabilities for the transitions between different neutrino flavors are calculated, and graphs representing the probabilities for the disappearance of muon neutrinos/antineutrinos and the appearance of electron neutrinos/antineutrinos in a beam of muon neutrinos/antineutrinos versus the distance from the neutrino source for various values of admissible model parameters at neutrino energies not higher than 50 MeV, as well as versus the ratio of this distance to the neutrino energy, are plotted. It is shown that the short-distance accelerator anomaly in neutrino data (LNSD anomaly) can be explained in the case of a specific mixing matrix for active and sterile neutrinos (which belongsmore » to the a{sub 2} type) at the chosen parameter values. The same applies to the short-distance reactor and gallium anomalies. The theoretical results obtained in the present study can be used to interpret and predict the results of ground-based neutrino experiments aimed at searches for sterile neutrinos, as well as to analyze some astrophysical observational data.« less

Authors:
; ;  [1]
  1. National Research Center Kurchatov Institute (Russian Federation)
Publication Date:
OSTI Identifier:
22612619
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Atomic Nuclei; Journal Volume: 79; Journal Issue: 5; Other Information: Copyright (c) 2016 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANTINEUTRINOS; CP INVARIANCE; DISTANCE; ELECTRON NEUTRINOS; FLAVOR MODEL; GALLIUM; MEV RANGE 10-100; MUON NEUTRINOS; NEUTRINO BEAMS; NEUTRINO OSCILLATION; REST MASS; STERILE NEUTRINOS

Citation Formats

Khruschov, V. V., E-mail: khruschov-vv@nrcki.ru, Fomichev, S. V., E-mail: fomichev-sv@nrcki.ru, and Titov, O. A., E-mail: titov-oa@nrcki.ru. Oscillation properties of active and sterile neutrinos and neutrino anomalies at short distances. United States: N. p., 2016. Web. doi:10.1134/S1063778816050124.
Khruschov, V. V., E-mail: khruschov-vv@nrcki.ru, Fomichev, S. V., E-mail: fomichev-sv@nrcki.ru, & Titov, O. A., E-mail: titov-oa@nrcki.ru. Oscillation properties of active and sterile neutrinos and neutrino anomalies at short distances. United States. doi:10.1134/S1063778816050124.
Khruschov, V. V., E-mail: khruschov-vv@nrcki.ru, Fomichev, S. V., E-mail: fomichev-sv@nrcki.ru, and Titov, O. A., E-mail: titov-oa@nrcki.ru. 2016. "Oscillation properties of active and sterile neutrinos and neutrino anomalies at short distances". United States. doi:10.1134/S1063778816050124.
@article{osti_22612619,
title = {Oscillation properties of active and sterile neutrinos and neutrino anomalies at short distances},
author = {Khruschov, V. V., E-mail: khruschov-vv@nrcki.ru and Fomichev, S. V., E-mail: fomichev-sv@nrcki.ru and Titov, O. A., E-mail: titov-oa@nrcki.ru},
abstractNote = {A generalized phenomenological (3 + 2 + 1) model featuring three active and three sterile neutrinos that is intended for calculating oscillation properties of neutrinos for the case of a normal active neutrino mass hierarchy and a large splitting between the mass of one sterile neutrino and the masses of the other two sterile neutrinos is considered. A new parametrization and a specific form of the general mixing matrix are proposed for active and sterile neutrinos with allowance for possible CP violation in the lepton sector, and test values are chosen for the neutrino masses and mixing parameters. The probabilities for the transitions between different neutrino flavors are calculated, and graphs representing the probabilities for the disappearance of muon neutrinos/antineutrinos and the appearance of electron neutrinos/antineutrinos in a beam of muon neutrinos/antineutrinos versus the distance from the neutrino source for various values of admissible model parameters at neutrino energies not higher than 50 MeV, as well as versus the ratio of this distance to the neutrino energy, are plotted. It is shown that the short-distance accelerator anomaly in neutrino data (LNSD anomaly) can be explained in the case of a specific mixing matrix for active and sterile neutrinos (which belongs to the a{sub 2} type) at the chosen parameter values. The same applies to the short-distance reactor and gallium anomalies. The theoretical results obtained in the present study can be used to interpret and predict the results of ground-based neutrino experiments aimed at searches for sterile neutrinos, as well as to analyze some astrophysical observational data.},
doi = {10.1134/S1063778816050124},
journal = {Physics of Atomic Nuclei},
number = 5,
volume = 79,
place = {United States},
year = 2016,
month = 9
}
  • We investigate adding two sterile neutrinos to resolve the apparent tension existing between short-baseline neutrino oscillation results and CPT-conserving, four-neutrino oscillation models. For both (3+1) and (3+2) models, the level of statistical compatibility between the combined dataset from the null short-baseline experiments Bugey, CHOOZ, CCFR84, CDHS, KARMEN, and NOMAD, on the one hand; and the LSND dataset, on the other, is computed. A combined analysis of all seven short-baseline experiments, including LSND, is also performed, to obtain the favored regions in neutrino mass and mixing parameter space for both models. Finally, four statistical tests to compare the (3+1) and themore » (3+2) hypotheses are discussed. All tests show that (3+2) models fit the existing short-baseline data significantly better than (3+1) models.« less
  • Light sterile neutrinos might mix with the active ones and be copiously produced in the early Universe. In the present paper, a detailed multi-flavor analysis of sterile neutrino production is performed. Making some justified approximations allows us to consider not only neutrino interactions with the primeval medium and neutrino coherence breaking effects, but also oscillation effects arising from the presence of three light (mostly-active) neutrino states mixed with two heavier (mostly-sterile) states. First, we emphasize the underlying physics via an analytical description of sterile neutrino abundances that is valid for cases with small mixing between active and sterile neutrinos. Then,more » we study in detail the phenomenology of (3+2) sterile neutrino models in light of short-baseline oscillation data, including the LSND and MiniBooNE results. Finally, by using the information provided by this analysis, we obtain the expected sterile neutrino cosmological abundances and then contrast them with the most recent available data from Cosmic Microwave Background and Large Scale Structure observations. We conclude that (3+2) models are significantly more disfavored by the internal inconsistencies between sterile neutrino interpretations of appearance and disappearance short-baseline data themselves, rather than by the used cosmological data.« less
  • We examine a recently proposed explanation of the liquid scintillator neutrino detector and MiniBooNE anomalies, given in terms of a sterile neutrino N of the mass 40MeV < or approx. m{sub N} < or approx. 80MeV mixed with {nu}{sub {mu}} at the strength 10{sup -3} < or approx. |U{sub {mu}N}|{sup 2} < or approx. 10{sup -2} and which dominantly decays into a light neutrino and photon: N{yields}{nu}{gamma}. We check compatibility of this scenario with the existing experimental data on radiative {tau}-lepton and K-meson decays. We find that neither of these data are able to totally rule out the above indicatedmore » region of m{sub N}-|U{sub {mu}N}|{sup 2}. However, we show that the current experimental data on K{yields}{mu}{nu}{gamma} decay exclude a significant part of this region. We propose experimental cuts on this decay allowing to improve its sensitivity to the region in question. We also show that measurements of K{yields}{mu}{nu}ee decay have good prospects for testing the decaying sterile neutrino scenario.« less
  • We investigate the extent to which leptonic CP-violation in (3+2) sterile neutrino models leads to different oscillation probabilities for {nu}{sub {mu}}{yields}{nu}{sub e} and {nu}{sub {mu}}{yields}{nu}{sub e} oscillations at MiniBooNE. We are using a combined analysis of short-baseline (SBL) oscillation results, including the LSND and null SBL results, to which we impose additional constraints from atmospheric oscillation data. We obtain the favored regions in MiniBooNE oscillation probability space for both (3+2) CP-conserving and (3+2) CP-violating models. We further investigate the allowed CP-violation phase values and the MiniBooNE reach for such a CP violation measurement. The analysis shows that the oscillation probabilitiesmore » in MiniBooNE neutrino and antineutrino running modes can differ significantly, with the latter possibly being as much as 3 times larger than the first. In addition, we also show that all possible values of the single CP-violation phase measurable at short baselines in (3+2) models are allowed within 99% CL by existing data.« less