scholarly journals Combined analysis of short-baseline neutrino experiments in the(3+1)and(3+2)sterile neutrino oscillation hypotheses

2004 ◽  
Vol 70 (7) ◽  
Author(s):  
M. Sorel ◽  
J. M. Conrad ◽  
M. H. Shaevitz
Keyword(s):  
Neutrino Oscillation ◽  
Sterile Neutrino ◽  
Short Baseline ◽  
Combined Analysis ◽  
Neutrino Experiments

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 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 Exploring the new physics phases in 3+1 scenario in neutrino oscillation experiments

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Nishat Fiza ◽  
Mehedi Masud ◽  
Manimala Mitra
Keyword(s):  
Neutrino Oscillation ◽  
Sterile Neutrino ◽  
New Physics ◽  
Double Beta Decay ◽  
Relevant Parameter ◽  
Neutrino Experiment ◽  
Short Baseline ◽  
Mixing Angles ◽  
Long Baseline ◽  
Deep Underground

Abstract The various global analyses of available neutrino oscillation data indicate the presence of the standard 3 + 0 neutrino oscillation picture. However, there are a few short baseline anomalies that point to the possible existence of a fourth neutrino (with mass in the eV-scale), essentially sterile in nature. Should sterile neutrino exist in nature and its presence is not taken into consideration properly in the analyses of neutrino data, the interference terms arising due to the additional CP phases in presence of a sterile neutrino can severely impact the physics searches in long baseline (LBL) neutrino oscillation experiments. In the current work we consider one light (eV-scale) sterile neutrino and probe all the three CP phases (δ13, δ24, δ34) in the context of the upcoming Deep Underground Neutrino Experiment (DUNE) and also estimate how the results improve when data from NOvA, T2K and T2HK are added in the analysis. We illustrate the ∆χ2 correlations of the CP phases among each other, and also with the three active-sterile mixing angles. Finally, we briefly illustrate how the relevant parameter spaces in the context of neutrinoless double beta decay get modified in light of the bounds in presence of a light sterile neutrino.

scholarly journals A new analysis of the MiniBooNE low-energy excess

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
C. Giunti ◽  
A. Ioannisian ◽  
G. Ranucci
Keyword(s):  
Neutrino Oscillation ◽  
Neutrino Oscillations ◽  
Sterile Neutrino ◽  
Statistical Significance ◽  
Photon Emission ◽  
Low Energy ◽  
Neutrino Mixing ◽  
Short Baseline ◽  
Energy Excess ◽  
Global Fit

Abstract We present the results of a new analysis of the data of the MiniBooNE experiment taking into account the additional background of photons from ∆+/0 decay proposed in ref. [1] and additional contributions due to coherent photon emission, incoherent production of higher mass resonances, and incoherent non-resonant nucleon production. We show that the new background can explain part of the MiniBooNE low-energy excess and the statistical significance of the MiniBooNE indication in favor of short-baseline neutrino oscillation decreases from 5.1σ to 3.6σ. We also consider the implications for short-baseline neutrino oscillations in the 3+1 active-sterile neutrino mixing framework. We show that the new analysis of the MiniBooNE data indicates smaller active-sterile neutrino mixing and may lead us towards a solution of the appearance-disappearance tension in the global fit of short-baseline neutrino oscillation data.

scholarly journals Sterile Neutrino Fits to Short-Baseline Neutrino Oscillation Measurements

2013 ◽  
Vol 2013 ◽  
pp. 1-26 ◽  
Author(s):  
J. M. Conrad ◽  
C. M. Ignarra ◽  
G. Karagiorgi ◽  
M. H. Shaevitz ◽  
J. Spitz
Keyword(s):  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
Goodness Of Fit ◽  
Sterile Neutrino ◽  
Low Energy ◽  
Data Sets ◽  
Sterile Neutrinos ◽  
Short Baseline ◽  
Energy Excess ◽  
Global Fit

This paper reviews short-baseline oscillation experiments as interpreted within the context of one, two, and three sterile neutrino models associated with additional neutrino mass states in the~1 eV range. Appearance and disappearance signals and limits are considered. We show that fitting short-baseline datasets to a 3 + 3 (3 + 2) model, defined by three active and three (two) sterile neutrinos, results in an overall goodness of fit of 67% (69%) and good compatibility between data sets—to be compared to a 3 + 1 model with a 55% goodness of fit. While the (3 + 3) fit yields the highest quality overall, it still finds inconsistencies with the MiniBooNE appearance datasets; in particular, the global fit fails to account for the observed MiniBooNE low-energy excess. Given the overall improvement, we recommend using the results of (3 + 2) and (3 + 3) fits, rather than (3 + 1) fits, for future neutrino oscillation phenomenology. These results motivate the pursuit of further short-baseline experiments, such as those reviewed in this paper.

scholarly journals Exploring Light Sterile Neutrinos at Long Baseline Experiments: A Review

Universe ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 41
Author(s):  
Antonio Palazzo
Keyword(s):  
Cp Violation ◽  
Sterile Neutrino ◽  
Mass Hierarchy ◽  
Short Baseline ◽  
Neutrino Mass Hierarchy ◽  
Long Baseline ◽  
Discovery Potential ◽  
Neutrino Experiments ◽  
The Impact

Several anomalies observed in short-baseline neutrino experiments suggest the existence of new light sterile neutrino species. In this review, we describe the potential role of long-baseline experiments in the searches of sterile neutrino properties and, in particular, the new CP-violation phases that appear in the enlarged 3 + 1 scheme. We also assess the impact of light sterile states on the discovery potential of long-baseline experiments of important targets such as the standard 3-flavor CP violation, the neutrino mass hierarchy, and the octant of θ 23 .

scholarly journals SHORT-BASELINE ACTIVE-STERILE NEUTRINO OSCILLATIONS?

2007 ◽  
Vol 22 (33) ◽  
pp. 2499-2509 ◽  
Author(s):  
CARLO GIUNTI ◽  
MARCO LAVEDER
Keyword(s):  
Neutrino Oscillation ◽  
Neutrino Oscillations ◽  
Sterile Neutrino ◽  
Mass Difference ◽  
Atmospheric Neutrino ◽  
Radioactive Source ◽  
Short Baseline

We suggest the possibility that the anomalies observed in the LSND experiment and the Gallium radioactive source experiments may be due to neutrino oscillations generated by a large squared-mass difference of about 20–30 eV2. We consider the simplest 3+1 four-neutrino scheme that can accommodate also the observed solar and atmospheric neutrino oscillations. We show that, in this framework, the disappearance of [Formula: see text] and [Formula: see text] in short-baseline neutrino oscillation experiments is mainly due to active-sterile transitions. The implications of the first MiniBooNE results, appeared after the completion of this paper, are discussed in an addendum.

scholarly journals ON RECONCILING ATMOSPHERIC, LSND, AND SOLAR NEUTRINO-OSCILLATION DATA

1998 ◽  
Vol 13 (28) ◽  
pp. 2249-2264 ◽  
Author(s):  
D. V. AHLUWALIA
Keyword(s):  
Neutrino Oscillation ◽  
Solar Neutrino ◽  
Sterile Neutrino ◽  
Atmospheric Neutrino ◽  
Neutrino Flux ◽  
Cpt Symmetry ◽  
Charge Conjugate ◽  
Mixing Matrix ◽  
Quantum Operators ◽  
Neutrino Experiments

The L/E-flatness of the e-like events observed in the recent atmospheric-neutrino data from super-Kamiokande (SuperK) is interpreted to reflect a new symmetry of the neutrino-oscillation mixing matrix. From that we obtain an analytical set of constraints yielding a class of mixing matrices of the property to simultaneously fit both the SuperK and the LSND data. The resulting mass squared difference relevant for the LSND experiment is found as 0.3 eV2. The discussed symmetry, e.g., carries the nature that expectation values of masses for νμ and ντ are identical. These considerations are purely data dictated. A different framework is then applied to the solar neutrino problem. It is argued that a single sterile neutrino is an unlikely candidate to accommodate the data from the four solar neutrino experiments. A scenario is discussed which violates CPT symmetry, and favors the [Formula: see text] system to belong to the "self"–"anti-self" charge conjugate construct in the (1/2, 0)⊕(0,1/2) representation space, where the needed helicity flipping amplitudes are preferred, rather than the usual Dirac, or Majorana, constructs. In the presented framework the emerging SuperK data on solar neutrino flux is reconciled with the Homestake, GALLEX, and SAGE experiments. This happens because the former detects not only the solar νe but also, at a lower cross-section, the oscillated solar [Formula: see text]; while the latter are sensitive only to the oscillation-diminished solar νe flux. A direct observation of solar [Formula: see text] by SNO will confirm our scenario. Finally, we consider the possibility for flavor-dependent gravitational couplings of neutrinos as emerging out of the noncommutativity of the quantum operators associated with the measurements of energy and flavor.

scholarly journals Improved short-baseline neutrino oscillation search and energy spectrum measurement with the PROSPECT experiment at HFIR

2021 ◽  
Vol 103 (3) ◽  
Author(s):  
M. Andriamirado ◽  
A. B. Balantekin ◽  
H. R. Band ◽  
C. D. Bass ◽  
D. E. Bergeron ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Neutrino Oscillation ◽  
Short Baseline ◽  
Spectrum Measurement
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