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 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 Unitarity of neutrino mixing matrix

2019 ◽  
Vol 206 ◽  
pp. 09009
Author(s):  
Ha Nguyen Thi Kim ◽  
Van Nguyen Thi Hong ◽  
Son Cao Van
Keyword(s):  
Cp Violation ◽  
Neutrino Oscillations ◽  
Graphical Form ◽  
Muon Neutrinos ◽  
Neutrino Mixing ◽  
Electron Neutrinos ◽  
Tau Neutrinos ◽  
The Matrix ◽  
Mixing Matrix ◽  
Unitary Triangle

Neutrinos are neutral leptons and there exist three types of neutrinos (electron neutrinos νe, muon neutrinos νµ and tau neutrinos ντ). These classifications are referred to as neutrinos’s “flavors”. Oscillations between the different flavors are known as neutrino oscillations, which occurs when neutrinos have mass and non-zero mixing. Neutrino mixing is governed by the PMNS mixing matrix. The PMNS mixing matrix is constructed as the product of three independent rotations. With that, we can describe the numerical parameters of the matrix in a graphical form called the unitary triangle, giving rise to CP violation. We can calculate the four parameters of the mixing matrix to draw the unitary triangle. The area of the triangle is a measure of the amount of CP violation.

scholarly journals Testing unitarity of the 3 × 3 neutrino mixing matrix in an atomic system

2020 ◽  
Vol 35 (01) ◽  
pp. 2050004
Author(s):  
Guo-Yuan Huang ◽  
Noboru Sasao ◽  
Zhi-Zhong Xing ◽  
Motohiko Yoshimura
Keyword(s):  
Degrees Of Freedom ◽  
Atomic System ◽  
Transition Process ◽  
Photon Spectrum ◽  
Neutrino Mixing ◽  
Seesaw Mechanism ◽  
Lepton Flavor ◽  
Mixing Parameters ◽  
Flavor Mixing ◽  
Mixing Matrix

Unitarity of the [Formula: see text] lepton flavor mixing matrix [Formula: see text] is unavoidably violated in a seesaw mechanism if its new heavy degrees of freedom are slightly mixed with the active neutrino flavors. We propose to use the atomic transition process [Formula: see text] (for [Formula: see text], [Formula: see text]), where [Formula: see text] and [Formula: see text] stand, respectively for the excited and ground levels of an atomic system, to probe or constrain the unitarity-violating effects of [Formula: see text]. We find that the photon spectrum of this transition will be distorted by the effects of [Formula: see text] and [Formula: see text] as compared with the [Formula: see text] case. We locate certain frequencies in the photon spectrum to minimize the degeneracy of effects of the unitarity violation and uncertainties of the flavor mixing parameters themselves. The requirements of a nominal experimental setup to test the unitarity of [Formula: see text] are briefly discussed.

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 CAN THE SUPER-KAMIOKANDE ATMOSPHERIC DATA PREDICT THE SOLAR NEUTRINO DEFICIT?

1999 ◽  
Vol 14 (10n11) ◽  
pp. 689-700 ◽  
Author(s):  
ION STANCU
Keyword(s):  
Solar Neutrino ◽  
Neutrino Oscillations ◽  
Atmospheric Neutrino ◽  
Neutrino Flux ◽  
Experimental Results ◽  
Neutrino Mixing ◽  
Mixing Angles ◽  
Atmospheric Data ◽  
Mixing Matrix ◽  
Good Agreement

In this letter we show that the evidence for neutrino oscillations from the super-Kamiokande atmospheric neutrino data fully determines the 3×3 neutrino-oscillations mixing matrix and predicts an energy-independent solar neutrino deficit at the level of 45%. This corresponds to a ratio of measured to predicted neutrino flux of [Formula: see text], in good agreement with the experimental results. We achieve this result within the framework of a minimal, three-generation neutrino mixing, with mass squared differences of ΔM2≃0.45 eV 2 and [Formula: see text]. The mixing matrix derived here is characterized by the mixing angles θ=35.1°, β=5.5° and ψ=23.3°, and a vanishing CP-violating phase, δ=0.

scholarly journals Global oscillation data analysis on the 3ν mixing without unitarity

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Zhuojun Hu ◽  
Jiajie Ling ◽  
Jian Tang ◽  
TseChun Wang
Keyword(s):  
Neutrino Oscillation ◽  
Current Data ◽  
Precision Measurements ◽  
Matrix Elements ◽  
Neutrino Mixing ◽  
Unitarity Triangle ◽  
Global Oscillation ◽  
Long Baseline ◽  
Mixing Matrix ◽  
The One

Abstract We present results of a combined analysis in neutrino oscillations without unitarity assumption in the 3ν mixing picture. Constraints on neutrino mixing matrix elements are based on recent data from the reactor, solar and long-baseline accelerator neutrino oscillation experiments. The current data are consistent with the standard 3ν scheme. The precision on different matrix elements can be as good as a few percent at 3σ CL, and is mainly limited by the experimental statistical uncertainty. The νe related elements are the most precisely measured among all sectors with the uncertainties < 20%. The measured leptonic CP violation is very close to the one assuming the standard 3ν mixing. The deviations on normalization and the unitarity triangle closure are confined within $$ \mathcal{O} $$ O (10−3), $$ \mathcal{O} $$ O (10−2) and $$ \mathcal{O} $$ O (10−1), for νe, νμ and ντ sectors, respectively. We look forward to the next-generation neutrino oscillation experiments such as DUNE, T2HK, and JUNO, especially the precision measurements on ντ oscillations, to significantly improve the precision of unitarity test on the 3ν mixing matrix.

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.

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