scholarly journals Neutrino oscillations in the presence of super-light sterile neutrinos

2016 ◽  
Vol 31 (20n21) ◽  
pp. 1650123 ◽  
Author(s):  
Paraskevi Divari ◽  
John Vergados
Keyword(s):  
Sterile Neutrino ◽  
Neutral Current ◽  
Neutron Number ◽  
Electron Neutrino ◽  
Number Density ◽  
Sterile Neutrinos ◽  
Short Baseline ◽  
The Earth ◽  
Reactor Neutrino ◽  
Neutrino Experiments

In this paper, we study the effect of conversion of super-light sterile neutrino (SLSN) to electron neutrino in matter like that of the Earth. In the Sun the resonance conversion between SLSN and electron neutrino via the neutral current is suppressed due to the smallness of neutron number. On the other hand, neutron number density can play an important role in the Earth, making the scenario of SLSN quite interesting. The effect of CP-violating phases on active-SLSN oscillations is also discussed. Reactor neutrino experiments with medium or short baseline may probe the scenario of SLSN.

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 Statistical interpretation of sterile neutrino oscillation searches at reactors

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Pilar Coloma ◽  
Patrick Huber ◽  
Thomas Schwetz
Keyword(s):  
Neutrino Oscillation ◽  
Sterile Neutrino ◽  
Statistical Significance ◽  
Statistical Interpretation ◽  
Actual Distribution ◽  
Mixing Angle ◽  
Log Likelihood ◽  
Reactor Neutrino ◽  
Neutrino Experiments ◽  
Experimental Effort

AbstractA considerable experimental effort is currently under way to test the persistent hints for oscillations due to an eV-scale sterile neutrino in the data of various reactor neutrino experiments. The assessment of the statistical significance of these hints is usually based on Wilks’ theorem, whereby the assumption is made that the log-likelihood is $$\chi ^2$$ χ 2 -distributed. However, it is well known that the preconditions for the validity of Wilks’ theorem are not fulfilled for neutrino oscillation experiments. In this work we derive a simple asymptotic form of the actual distribution of the log-likelihood based on reinterpreting the problem as fitting white Gaussian noise. From this formalism we show that, even in the absence of a sterile neutrino, the expectation value for the maximum likelihood estimate of the mixing angle remains non-zero with attendant large values of the log-likelihood. Our analytical results are then confirmed by numerical simulations of a toy reactor experiment. Finally, we apply this framework to the data of the Neutrino-4 experiment and show that the null hypothesis of no-oscillation is rejected at the 2.6 $$\sigma $$ σ level, compared to 3.2 $$\sigma $$ σ obtained under the assumption that Wilks’ theorem applies.

scholarly journals Study of oscillations with accelerator and reactor neutrinos

2018 ◽  
Vol 191 ◽  
pp. 01001
Author(s):  
Yury Kudenko
Keyword(s):  
Present Status ◽  
Sterile Neutrino ◽  
Experimental Status ◽  
Short Overview ◽  
Reactor Neutrino ◽  
Reactor Neutrinos ◽  
Neutrino Experiments

The present status of accelerator and reactor neutrino experiments and new results are presented. A short overview of future projects is also given. The experimental status of sterile neutrino searches is briefly discussed.

scholarly journals IceCube Sterile Neutrino Searches

2019 ◽  
Vol 207 ◽  
pp. 04005 ◽  
Author(s):  
B. J. P. Jones
Keyword(s):  
Large Volume ◽  
Sterile Neutrino ◽  
Large Mass ◽  
Neutrino Telescope ◽  
Muon Neutrino ◽  
Sterile Neutrinos ◽  
Short Baseline ◽  
Mixing Angles ◽  
Neutrino Telescopes ◽  
Ongoing Work

Anomalies in short baseline experiments have been interpreted as evidence for additional neutrino mass states with large mass splittings from the known, active flavors. This explanation mandates a corresponding signature in the muon neutrino disappearance channel, which has yet to be observed. Searches for muon neutrino disappearance at the IceCube neutrino telescope presently provide the strongest limits in the space of mixing angles for eVscale sterile neutrinos. This proceeding for the Very Large Volume Neutrino Telescopes (VLVnT) Workshop summarizes the IceCube analyses that have searched for sterile neutrinos and describes ongoing work toward enhanced, high-statistics sterile neutrino searches.

scholarly journals Reactor neutrino experiments: θ13 and beyond

2014 ◽  
Vol 29 (16) ◽  
pp. 1430016 ◽  
Author(s):  
Xin Qian ◽  
Wei Wang
Keyword(s):  
New Physics ◽  
Daya Bay ◽  
Neutrino Experiment ◽  
Mass Hierarchy ◽  
Neutrino Mixing ◽  
Next Generation ◽  
Short Baseline ◽  
Current Generation ◽  
Reactor Neutrino ◽  
Neutrino Experiments

We review the current-generation short-baseline reactor neutrino experiments that have firmly established the third neutrino mixing angle θ13 to be nonzero. The relative large value of θ13 (around 9°) has opened many new and exciting opportunities for future neutrino experiments. Daya Bay experiment with the first measurement of [Formula: see text] is aiming for a precision measurement of this atmospheric mass-squared splitting with a comparable precision as [Formula: see text] from accelerator muon neutrino experiments. JUNO, a next-generation reactor neutrino experiment, is targeting to determine the neutrino mass hierarchy (MH) with medium baselines (~ 50 km). Beside these opportunities enabled by the large θ13, the current-generation (Daya Bay, Double Chooz, and RENO) and the next-generation (JUNO, RENO-50, and PROSPECT) reactor experiments, with their unprecedented statistics, are also leading the precision era of the three-flavor neutrino oscillation physics as well as constraining new physics beyond the neutrino Standard Model.

scholarly journals keV sterile neutrino with large mixing angle is still alive

2018 ◽  
Vol 191 ◽  
pp. 08003
Author(s):  
Anton Chudaykin
Keyword(s):  
Sterile Neutrino ◽  
Sterile Neutrinos ◽  
Mixing Angle ◽  
Mixing Angles ◽  
Hidden Sector ◽  
The Standard Model ◽  
Neutrino Experiments ◽  
Active Mixing ◽  
Neutrino Decay ◽  
Made In

We study production of keV scale sterile neutrinos with large mixing with the Standard Model sector [1]. Conventional mechanism of sterile neutrino generation in the early Universe leads to overproduction of the Dark Matter and strong X-ray signal from sterile neutrino decay. It makes anticipated groundbased experiments on direct searches of sterile-active mixing unfeasible. We argue that for models with a hidden sector coupled to the sterile neutrinos cosmological and astrophysical constraints can be significantly alleviated. In developed scenario a phase transition in the hidden sector modifies the standard oscillation picture and leads to significantly larger mixing angles, thus opening new perspectives for future neutrino experiments such as Troitsk v-mass and KATRIN. This work was made in collaboration with Fedor Bezrukov and Dmitry Gorbunov.

scholarly journals REVIEW OF SOLAR AND REACTOR NEUTRINOS

2006 ◽  
Vol 21 (08n09) ◽  
pp. 1855-1868 ◽  
Author(s):  
ALAN W. P. POON
Keyword(s):  
Neutrino Oscillation ◽  
Direct Evidence ◽  
The Sun ◽  
The Earth ◽  
The Future ◽  
Reactor Neutrino ◽  
Reactor Neutrinos ◽  
Neutrino Experiments

Over the last several years, experiments have conclusively demonstrated that neutrinos are massive and that they mix. There is now direct evidence for νe s from the Sun transforming into other active flavors while en route to the Earth. The disappearance of reactor [Formula: see text], predicted under the assumption of neutrino oscillation, has also been observed. In this paper, recent results from solar and reactor neutrino experiments and their implications are reviewed. In addition, some of the future experimental endeavors in solar and reactor neutrinos are presented.

scholarly journals STERILE NEUTRINO PRODUCTION THROUGH A MATTER EFFECT ENHANCEMENT AT LONG BASELINES

2013 ◽  
Vol 28 (16) ◽  
pp. 1350067 ◽  
Author(s):  
JOSEPH BRAMANTE
Keyword(s):  
Standard Model ◽  
Sterile Neutrino ◽  
Neutral Current ◽  
Sterile Neutrinos ◽  
Vector Coupling ◽  
Neutrino Production ◽  
Long Baseline ◽  
Current Events ◽  
Matter Effect ◽  
Long Baselines

If sterile neutrinos have a neutral coupling to standard model fermions, matter effect resonant transitions to sterile neutrinos and excess neutral-current events could manifest at long baseline experiments. Assuming a single sterile neutrino with a neutral coupling to fermionic matter, we re-examine bounds on sterile neutrino production at long baselines from the MINOS result Pνμ →νs < 0.22 (90% CL). We demonstrate that sterile neutrinos with a neutral vector coupling to fermionic matter could evade the MINOS limit, allowing a higher fraction of active to sterile neutrino conversion at long baselines. Scanning the parameter space of sterile neutrino matter effect fits of the LSND and MiniBooNe data, we show that in the case of a vector singlet coupling of sterile neutrinos to matter, some favored parametrizations of these fits would create neutral-current event excesses above standard model predictions at long baseline experiments (e.g. MINOS and OPERA).

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