scholarly journals Minimal active-sterile neutrino mixing in seesaw type I mechanism with sterile neutrinos at GeV scale

2014 ◽  
Vol 89 (1) ◽  
Author(s):  
Dmitry Gorbunov ◽  
Alexander Panin
Keyword(s):  
Sterile Neutrino ◽  
Type I ◽  
Neutrino Mixing ◽  
Sterile Neutrinos

scholarly journals Numerical estimate of minimal active-sterile neutrino mixing

2018 ◽  
Vol 191 ◽  
pp. 03003
Author(s):  
Igor Krasnov
Keyword(s):  
Neutrino Mass ◽  
Sterile Neutrino ◽  
Numerical Estimate ◽  
Strong Dependence ◽  
Type I ◽  
Mass Hierarchy ◽  
Neutrino Mixing ◽  
Sterile Neutrinos ◽  
Mixing Angles ◽  
Active Neutrino

Seesaw mechanism constrains from below mixing between active and sterile neutrinos for fixed sterile neutrino masses. Signal events associated with sterile neutrino decays inside a detector at fixed target experiment are suppressed by the mixing angle to the power of four. Therefore sensitivity of experiments such as SHiP and DUNE should take into account minimal possible values of the mixing angles. We extend the previous study of this subject [1] to a more general case of non-zero CP-violating phases in the neutrino sector. Namely, we provide numerical estimate of minimal value of mixing angles between active neutrinos and two sterile neutrinos with the third sterile neutrino playing no noticeable role in the mixing. Thus we obtain a sensitivity needed to fully explore the seesaw type I mechanism for sterile neutrinos with masses below 2 GeV, and one undetectable sterile neutrino that is relevant for the fixedtarget experiments. Remarkably, we observe a strong dependence of this result on the lightest active neutrino mass and the neutrino mass hierarchy, not only on the values of CP-violating phases themselves. All these effects sum up to push the limit of experimental confirmation of sterile-active neutrino mixing by several orders of magnitude below the results of [1] from 10-10 - 10-11 down to 10-12 and even to 10-20 in parts of parameter space; non-zero CP-violating phases are responsible for that.

scholarly journals Search for signatures of sterile neutrinos with Double Chooz

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
T. Abrahão ◽  
H. Almazan ◽  
J. C. dos Anjos ◽  
S. Appel ◽  
J. C. Barriere ◽  
...  
Keyword(s):  
Model Prediction ◽  
Sterile Neutrino ◽  
Profile Likelihood ◽  
Mass Range ◽  
Neutrino Mixing ◽  
Sterile Neutrinos ◽  
Mixing Angles ◽  
Data Comparison ◽  
Mixing Parameter ◽  
Double Chooz

AbstractWe present a search for signatures of neutrino mixing of electron anti-neutrinos with additional hypothetical sterile neutrino flavors using the Double Chooz experiment. The search is based on data from 5 years of operation of Double Chooz, including 2 years in the two-detector configuration. The analysis is based on a profile likelihood, i.e. comparing the data to the model prediction of disappearance in a data-to-data comparison of the two respective detectors. The analysis is optimized for a model of three active and one sterile neutrino. It is sensitive in the typical mass range $${5 \times 10^{-3}}\,\mathrm{eV}^2 \lesssim \varDelta m^2_{41} \lesssim {3 \times 10^{-1}}\,\mathrm{eV}^2 $$ 5 × 10 - 3 eV 2 ≲ Δ m 41 2 ≲ 3 × 10 - 1 eV 2 for mixing angles down to $$\sin ^2 2\theta _{14} \gtrsim {0.02} $$ sin 2 2 θ 14 ≳ 0.02 . No significant disappearance additionally to the conventional disappearance related to $$\theta _{13} $$ θ 13 is observed and correspondingly exclusion bounds on the sterile mixing parameter $$\theta _{14} $$ θ 14 as a function of $$ \varDelta m^2_{41} $$ Δ m 41 2 are obtained.

scholarly journals Roles of sterile neutrinos in particle physics and cosmology

2019 ◽  
Vol 34 (10) ◽  
pp. 1930005 ◽  
Author(s):  
Sin Kyu Kang
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Sterile Neutrino ◽  
Electron Neutrino ◽  
Type I ◽  
Sterile Neutrinos ◽  
Short Baseline ◽  
Cosmological Observations ◽  
Cosmological Data ◽  
Electron Neutrino Appearance

The impacts of the light sterile neutrino hypothesis in particle physics and cosmology are reviewed. The observed short baseline neutrino anomalies challenging the standard explanation of neutrino oscillations within the framework of three active neutrinos are addressed. It is shown that they can be interpreted as the experimental hints pointing towards the existence of sterile neutrino at the eV scale. While the electron neutrino appearance and disappearance data are in favor of such a sterile neutrino, the muon disappearance data disfavor it, which gives rise to a strong appearance–disappearance tension. After a brief review on the cosmological effects of light sterile neutrinos, proposed signatures of light sterile neutrinos in the existing cosmological data are discussed. The keV-scale sterile neutrinos as possible dark matter candidates are also discussed by reviewing different mechanisms of how they can be produced in the early Universe and how their properties can be constrained by several cosmological observations. We give an overview of the possibility that keV-scale sterile neutrino can be a good DM candidate and play a key role in achieving low-scale leptogenesis simultaneously by introducing a model where an extra light sterile neutrino is added on top of type I seesaw model.

scholarly journals Supernova bounds on keV-mass sterile neutrinos

2015 ◽  
Vol 30 (13) ◽  
pp. 1530033 ◽  
Author(s):  
Shun Zhou
Keyword(s):  
Dark Matter ◽  
Energy Loss ◽  
Cold Dark Matter ◽  
Sterile Neutrino ◽  
Small Scale ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Sterile Neutrinos ◽  
Mixing Angles ◽  
Standard Energy

Sterile neutrinos of keV masses are one of the most promising candidates for the warm dark matter, which could solve the small-scale problems encountered in the scenario of cold dark matter. We present a detailed study of the production of such sterile neutrinos in a supernova core, and derive stringent bounds on the active-sterile neutrino mixing angles and sterile neutrino masses based on the standard energy-loss argument.

scholarly journals Neutrino-induced reactions in core-collapse supernovae: Effects on the electron fraction

2018 ◽  
Vol 27 (12) ◽  
pp. 1850116 ◽  
Author(s):  
M. M. Saez ◽  
O. Civitarese ◽  
M. E. Mosquera
Keyword(s):  
Neutrino Oscillations ◽  
Sterile Neutrino ◽  
Mass Difference ◽  
Hindrance Factor ◽  
Core Collapse ◽  
Neutrino Mixing ◽  
Sterile Neutrinos ◽  
Mixing Parameters ◽  
Difference Formula ◽  
R Process

Neutrino-induced reactions are a basic ingredient in astrophysical processes like star evolution. The existence of neutrino oscillations affects the rate of nuclear electroweak decays which participates in the chain of events that determines the fate of the star. Among the processes of interest, the production of heavy elements in core-collapse supernovae is strongly dependent upon neutrino properties, like the mixing between different species of neutrinos. In this work, we study the effects of neutrino oscillations upon the electron fraction as a function of the neutrino mixing parameters, for two schemes: the [Formula: see text]-scheme (one active neutrino and one sterile neutrino) and the [Formula: see text]-scheme (two active neutrinos and one sterile neutrino). We have performed this analysis considering a core-collapse supernovae and determined the physical conditions needed to activate the nuclear reaction chains involved in the r-process. We found that the interactions of the neutrinos with matter and among themselves and the initial amount of sterile neutrinos in the neutrino-sphere might change the electron fraction, therefore affecting the onset of the r-process. We have set constrains on the active-sterile neutrino mixing parameters. They are the square-mass-difference [Formula: see text], the mixing angle [Formula: see text], and the hindrance factor [Formula: see text] for the occupation of sterile neutrinos. The calculations have been performed for different values of [Formula: see text], which is the fraction of [Formula: see text]-particles. For [Formula: see text] the r-process is taking place if [Formula: see text], [Formula: see text] and [Formula: see text]. For larger values of [Formula: see text] the region of parameters is strongly reduced. The present results are compared to results available in the literature.

scholarly journals INVISIBLE Z DECAY WIDTH BOUNDS ON ACTIVE-STERILE NEUTRINO MIXING IN THE (3+1) AND (3+2) MODELS

2009 ◽  
Vol 24 (06) ◽  
pp. 475-483
Author(s):  
C. A. DE S. PIRES
Keyword(s):  
Decay Width ◽  
Sterile Neutrino ◽  
Matrix Elements ◽  
Neutrino Mixing ◽  
Sterile Neutrinos ◽  
Mixing Matrix ◽  
The Invisible

In this work we consider scenarios where light sterile neutrinos are mixed with the active ones. The active-sterile neutrino mixings render new contributions to the invisible Z decay width which will depend predominantly on the active-sterile mixing matrix elements. We then use the current experimental value of the invisible Z decay width to obtain bounds on these mixing matrix elements for both (3+1) and (3+2) models.

scholarly journals Current and future neutrino oscillation constraints on leptonic unitarity

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Sebastian A. R. Ellis ◽  
Kevin J. Kelly ◽  
Shirley Weishi Li
Keyword(s):  
Precise Measurement ◽  
Sterile Neutrino ◽  
Current Knowledge ◽  
Unknown Origin ◽  
Neutrino Masses ◽  
Matrix Elements ◽  
Neutrino Mixing ◽  
Next Generation ◽  
Active Neutrino ◽  
Mixing Matrix

Abstract The unitarity of the lepton mixing matrix is a critical assumption underlying the standard neutrino-mixing paradigm. However, many models seeking to explain the as-yet-unknown origin of neutrino masses predict deviations from unitarity in the mixing of the active neutrino states. Motivated by the prospect that future experiments may provide a precise measurement of the lepton mixing matrix, we revisit current constraints on unitarity violation from oscillation measurements and project how next-generation experiments will improve our current knowledge. With the next-generation data, the normalizations of all rows and columns of the lepton mixing matrix will be constrained to ≲10% precision, with the e-row best measured at ≲1% and the τ-row worst measured at ∼10% precision. The measurements of the mixing matrix elements themselves will be improved on average by a factor of 3. We highlight the complementarity of DUNE, T2HK, JUNO, and IceCube Upgrade for these improvements, as well as the importance of ντ appearance measurements and sterile neutrino searches for tests of leptonic unitarity.

scholarly journals New results from the DANSS experiment

2020 ◽  
Vol 35 (34n35) ◽  
pp. 2044015
Author(s):  
Nataliya Skrobova
Keyword(s):  
Nuclear Power ◽  
Sterile Neutrino ◽  
Reactor Core ◽  
Detector Efficiency ◽  
Sterile Neutrinos ◽  
Inverse Beta Decay ◽  
Systematic Uncertainties ◽  
Interesting Part ◽  
Raster Scan ◽  
Kalinin Nuclear Power Plant

We present new results of the DANSS experiment on the searches for sterile neutrinos. They are based on more than 2 million of inverse beta decay events collected at 10.7 m, 11.7 m and 12.7 m from the reactor core of the 3.1 GW Kalinin Nuclear Power Plant in Russia. This data sample is 2.4 times larger than the data sample in the previous DANSS publication. The search for the sterile neutrinos is performed using the ratio of [Formula: see text] spectra at two distances. This method is very robust against systematic uncertainties in the [Formula: see text] spectrum and the detector efficiency. We do not see any statistically significant sign for the [Formula: see text] oscillations. This allows us to exclude further a large and interesting part of the sterile neutrino parameter space. A Gaussian CL[Formula: see text] method was used to obtain exclusion areas. This method is more conservative than a Raster Scan method.

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