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.

EFFECTS OF CP VIOLATING PHASES ON THE INVERSE NEUTRINOLESS DOUBLE BETA SCATTERING e-e- → W-W-

2012 ◽  
Vol 27 (14) ◽  
pp. 1250053
Author(s):  
S. AKASLAN ◽  
A. U. YILMAZER
Keyword(s):  
Double Beta Decay ◽  
Neutrino Masses ◽  
Matrix Elements ◽  
Neutrino Mixing ◽  
Open Problems ◽  
Helicity Amplitudes ◽  
Mixing Matrix ◽  
The Masses ◽  
Positive Results

The most important open problems of the today's neutrino physics are the absolute values of the neutrino masses, the determination of the Dirac or the Majorana character and better measurements of the mixing matrix elements. Results of the neutrino oscillations experiments strongly confirm that the neutrinos have nonzero masses. Experiments give information about the differences between the squares of the masses but not any knowledge on their absolute values. Similarly neutrino oscillation phenomena does not help us to understand their Dirac or Majorana character. One of the processes that could clarify this important point is the double beta decay and the search is still going on but not yielded any positive results due to the big experimental difficulties. Also the inverse of this decay, e-e- → W-W- is another process that could be tested at the accelerators. This process is possible only if the neutrinos have masses and they are Majorana particles. Since neutrinos could have very tiny masses and the cross section of the above process is proportional to the square of the effective neutrino mass it is an extremely rare process. Also it violates total lepton number by two units, Δ = 2. In the literature the inverse neutrinoless double beta scattering have been extensively studied, in this article we obtain the relevant helicity amplitudes, investigate the effects of the neutrino mixing matrix elements, especially the roles of the CP violating phases and the possible CP asymmetries.

scholarly journals SUM RULES OF FOUR-NEUTRINO MIXING IN MATTER

2007 ◽  
Vol 22 (18) ◽  
pp. 1341-1347 ◽  
Author(s):  
HE ZHANG
Keyword(s):  
Cp Violation ◽  
Sum Rules ◽  
Sterile Neutrino ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Long Baseline ◽  
Mixing Parameters ◽  
Flavor Mixing ◽  
Mixing Matrix ◽  
Model Independent

Assuming the existence of one light sterile neutrino, we investigate the neutrino flavor mixing matrix in matter. Sum rules between the mixing parameters in vacuum and their counterparts in matter are derived. By using these new sum rules, we obtain the simple but exact expressions of the effective flavor mixing matrix in matter in terms of neutrino masses and the mixing parameters in vacuum. The rephasing invariants, sides of unitarity quadrangles and oscillation probabilities in matter are also achieved. Our model-independent results will be very helpful for analyzing flavor mixing and CP violation in the future long-baseline neutrino oscillation experiments.

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.

THREE-NEUTRINO OSCILLATIONS IN MATTER, CP-VIOLATION AND TOPOLOGICAL PHASES

1992 ◽  
Vol 01 (02) ◽  
pp. 379-399 ◽  
Author(s):  
V.A. NAUMOV
Keyword(s):  
Evolution Operator ◽  
Adiabatic Approximation ◽  
Neutrino Oscillations ◽  
Topological Phases ◽  
Matrix Elements ◽  
Neutrino Mixing ◽  
Time Evolution Operator ◽  
Adiabatic Approach ◽  
Flavor Mixing ◽  
Mixing Matrix

The phenomenon of Dirac neutrino oscillations in medium of varying density and composition is studied for the case of three lepton generations using the Berry adiabatic approach. The expressions for the topological phases γN are derived. It is shown that the Berry phases, arising when matter parameters vary periodically, are equal to zero identically, while in the case of noncyclic evolution, γN≢0 (in a special gauge) under the condition that all matrix elements of the flavor-mixing matrix in vacuum, CP-violating (Dirac) phase and neutrino-mass-squares differences are not equal to zero simultaneously. Exact formulas for the neutrino-mixing matrix in matter and adiabatic time-evolution operator are obtained. The recursion algorithm for the calculation of corrections to the adiabatic approximation is given

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 $$3+1$$ 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 NEUTRINO OSCILLATIONS AND LEPTON FLAVOR MIXING

2001 ◽  
Vol 16 (33) ◽  
pp. 2169-2175 ◽  
Author(s):  
KYUNGSIK KANG ◽  
SIN KYU KANG ◽  
C. S. KIM ◽  
SUN MYONG KIM
Keyword(s):  
Neutrino Mass ◽  
Mass Matrix ◽  
Neutrino Masses ◽  
Input Constraints ◽  
Neutrino Mixing ◽  
Lepton Flavor ◽  
Invariance Violation ◽  
The Family ◽  
Flavor Mixing ◽  
Mixing Matrix

In view of the recent announcement on nonzero neutrino mass from Super-Kamiokande experiment, it would be very timely to investigate all the possible scenarios on masses and mixings of light neutrinos. Recently suggested mass matrix texture for the quark CKM mixing, which can be originated from the family permutation symmetry and its suitable breakings, is assumed for the neutrino mass matrix and determined by the four combinations of solar, atmospheric and LSND neutrino data and cosmological hot dark matter bound as input constraints. The charged-lepton mass matrix is assumed to be diagonal so that the neutrino mixing matrix can be identified directly as the lepton flavor mixing matrix and no CP invariance violation originates from the leptonic sector. The results favor hierarchical patterns for the neutrino masses, which follow from the case when the solar-atmospheric data is used.

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.

Sign in / Sign up

Export Citation Format

Share Document