scholarly journals Active–sterile neutrino mixing in the absence of bare active neutrino mass

2006 ◽  
Vol 749 (1-3) ◽  
pp. 153-171 ◽  
Author(s):  
Yi Liao
Keyword(s):  
Neutrino Mass ◽  
Sterile Neutrino ◽  
Neutrino Mixing ◽  
Active Neutrino

scholarly journals Effects of active–sterile neutrino mixing during primordial nucleosynthesis

2014 ◽  
Vol 23 (12) ◽  
pp. 1450080 ◽  
Author(s):  
Osvaldo Civitarese ◽  
Mercedes Elisa Mosquera ◽  
María Manuela Sáez
Keyword(s):  
Neutrino Mass ◽  
Sterile Neutrino ◽  
Distribution Functions ◽  
Light Nuclei ◽  
Neutrino Mixing ◽  
Mixing Angles ◽  
A Value ◽  
Active Neutrino ◽  
Observable Data ◽  
Free Parameters

In the present work, we discuss the effects of the inclusion of sterile–active neutrino oscillations during the production of primordial light-nuclei. We assume that the sterile neutrino mass-eigenstate might oscillate with the two lightest active neutrino mass-eigenstates, with mixing angles ϕ1 and ϕ2. We also allow a constant renormalization (represented by a parameter (ζ)) of the sterile neutrino occupation factor. Taking ζ and the mixing angles as free parameters, we have computed distribution functions of active and sterile neutrinos and primordial abundances. Using observable data we set constrains in the free parameters of the model. It is found that the data on primordial abundances are consistent with small mixing angles and with a value of ζ smaller than 0.65 at 3σ level.

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 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 $$3+1$$ active–sterile neutrino mixing in $$B-L$$ model with $$S_{3}{\times Z_4\times Z_2}$$ symmetry for normal neutrino mass ordering

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
V. V. Vien
Keyword(s):  
Neutrino Mass ◽  
Sterile Neutrino ◽  
Mass Matrix ◽  
Neutrino Masses ◽  
Yukawa Interaction ◽  
Neutrino Mixing ◽  
Normal Ordering ◽  
Mixing Angles ◽  
Active Mixing ◽  
Best Fit

AbstractWe propose a non-renormalizable $$B-L$$ B - L model with $$S_{3}{\times Z_4\times Z_2}$$ S 3 × Z 4 × Z 2 symmetry which successfully accommodates the current active–sterile neutrino mixing in $$3+1$$ 3 + 1 scheme. The $$S_3$$ S 3 flavor symmetry is supplemented by $$Z_4\otimes Z_2$$ Z 4 ⊗ Z 2 symmetry to consolidate the Yukawa interaction of the model. The presence of $$S_3\otimes Z_4\otimes Z_2$$ S 3 ⊗ Z 4 ⊗ Z 2 flavour symmetry plays an important role in generating the desired structure of the neutrino mass matrix. The model can reproduce the recent observed active-neutrino neutrino oscillation data for normal ordering in which two sterile–active mixing angles $$\theta _{14, 24}$$ θ 14 , 24 get the best-fit values and the obtained values of $$\theta _{34}, \delta _{14}, \delta _{14}$$ θ 34 , δ 14 , δ 14 , the sum of neutrino mass and the effective neutrino masses are within their currently allowed ranges.

scholarly journals Understanding the masses and mixings of one-zero textures in 3+1 scenario

2016 ◽  
Vol 31 (24) ◽  
pp. 1650132 ◽  
Author(s):  
Newton Nath ◽  
Monojit Ghosh ◽  
Shivani Gupta
Keyword(s):  
Mass Spectrum ◽  
Neutrino Mass ◽  
Sterile Neutrino ◽  
Mass Matrix ◽  
Neutrino Mass Matrix ◽  
Neutrino Sector ◽  
Mixing Parameters ◽  
Active Neutrino ◽  
Matrix Formula ◽  
The Masses

We present a detailed analysis and phenomenological consequences of neutrino mass matrix, [Formula: see text], with one-zero texture in the flavor basis where the active neutrino sector is extended by one sterile neutrino (3[Formula: see text]+[Formula: see text]1 case). In particular, our aim is to explore behavior of the sterile mixing parameters in detail when one of the elements of the neutrino mass matrix goes to zero. To study this, we consider two distinct mass spectrum of the active neutrinos: (i) completely hierarchical mass spectrum with a vanishing neutrino mass and (ii) completely quasidegenerate mass spectrum. In 3[Formula: see text]+[Formula: see text]1 scenario, the low energy neutrino mass matrix, [Formula: see text], is a [Formula: see text] matrix and has 10 independent elements. Thus it can have 10 possible one-zero textures. From the earlier studies it can be inferred that, if one assumes one vanishing neutrino mass, then only seven of these [Formula: see text] are phenomenologically allowed by the current neutrino oscillation data. On the other hand, if the neutrinos are quasidegenerate then there are eight phenomenologically viable one-zero textures. In this paper, we study the correlations between the sterile mixing parameters for each of these allowed textures for both mass spectrum and also their implications on the effective Majorana mass.

scholarly journals NEUTRINO OSCILLATIONS AND THE EXACT PARITY MODEL

1994 ◽  
Vol 09 (02) ◽  
pp. 169-179 ◽  
Author(s):  
R. FOOT
Keyword(s):  
Neutrino Mass ◽  
General Result ◽  
Neutrino Oscillations ◽  
Mass Matrix ◽  
Atmospheric Neutrino ◽  
Solar Neutrinos ◽  
Specific Model ◽  
Neutrino Mixing ◽  
Mixing Angles ◽  
Significant Deficit

We re-examine neutrino oscillations in exact parity models. Previously it was shown in a specific model that large neutrino mixing angles result. We show here that this is a general result of neutrino mixing in exact parity models provided that the neutrino mass matrix is real. In this case, the effects of neutrino mixing in exact parity models is such that the probability of a given weak eigenstate remaining in that eigenstate averages to less than half when averaged over many oscillations. This result is interesting in view of the accumulating evidence for a significant deficit in the number of solar neutrinos. It may also be of relevance to the atmospheric neutrino anomaly.

scholarly journals Effect on Jarlskog Determinant Above the GUT Scale Within Four Flavor Neutrino Framework

2021 ◽  
Author(s):  
Vivek Kumar Nautiyal ◽  
Bipin Singh Koranga
Keyword(s):  
Neutrino Mass ◽  
Scale Effects ◽  
Mass Matrix ◽  
Gravitational Interaction ◽  
Planck Scale ◽  
Neutrino Mixing ◽  
Gut Scale ◽  
Jarlskog Determinant ◽  
Planck Scale Effects ◽  
Four Flavor

AbstractWe study the Planck scale effects on Jarlskog determiant in the four flavor framework. On electroweak symmetry breaking, quantum gravitational effects lead to an effective SU(2) × U(1) invariant dimension-5 Lagrangian including neutrino and Higgs forces, which perturbed the neutrino mass term and produce an extra terms in the neutrino mass matrix. We consider that gravitational interaction is independent from flavor and compute the Jarlskog determiant due to Planck scale effects. In the case of leptonic sector, the strentgh of CP violation is measured by Jarlskog determiant. We applied our approach to study Jarlskog determinant in the four flavor neutrino mixing above the GUT scale.

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