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 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 Almost Maximally Broken Permutation Symmetry for Neutrino Mass Matrix

1997 ◽  
Vol 12 (16) ◽  
pp. 1175-1184 ◽  
Author(s):  
Kyungsik Kang ◽  
Sin Kyu Kang ◽  
Jihn E. Kim ◽  
Pyungwon Ko
Keyword(s):  
Mass Matrix ◽  
Atmospheric Neutrino ◽  
Current Data ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Family Symmetry ◽  
Majorana Neutrinos ◽  
Charged Leptons ◽  
The Masses

Assuming three light neutrinos are Majorana particles, we propose mass matrix ansatz for the charged leptons and Majorana neutrinos with family symmetry S3 broken into S1 and S2, respectively. Each matrix has three parameters, which are fixed by measured charged lepton masses, differences of squared neutrino masses relevant to the solar and the atmospheric neutrino puzzles, and the masses of three light Majorana neutrinos as a candidate for hot dark matter with ∑|mν|~ 6 eV . The resulting neutrino mixing is compatible with the data for the current upper limit, <mνe> th <0.7 eV , of neutrino-less double beta decay experiments, and the current data for various types of neutrino oscillation experiments. One solution of our model predicts that νμ→ντ oscillation probability is about < 0.008 with Δm2 ~ 10-2 eV 2, which may not be accessible at CHORUS and other on-going experiments.

scholarly journals A Phenomenological Model of Effectively Oscillating Massless Neutrinos and Its Implications

2020 ◽  
Vol 240 ◽  
pp. 02002
Author(s):  
Jianlong Lu ◽  
Aik Hui Chan ◽  
Choo Hiap Oh
Keyword(s):  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
Phenomenological Model ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Mass Hierarchy ◽  
Neutrino Mixing ◽  
Open Problems ◽  
Neutrino Mass Hierarchy ◽  
Flavor Changing

We discuss an alternative picture of neutrino oscillation. In this phenomenological model, the flavor-changing phenomena of massless neutrinos arise from scattering processes between neutrinos and four types of undetected spin-0 massive particles pervading throughout the Universe, instead of neutrinos’ own nature. These scattering processes are kinematically similar to Compton scattering. One type of left-handed massless sterile neutrino is needed in order to reproduce the neutrino oscillation modes predicted in the theory of neutrino mixing. Implications of our model include the existence of sterile neu- trinos, the nonconservation of active neutrinos, the possible mismatch among three neutrino mass squared differences ∆m2ij interpreted in the theory of neutrino mixing, the spacetime dependence of neutrino oscillation, and the impossibility of neutrinoless double beta decay. Several important open problems in neutrino physics become trivial or less severe in our model, such as the smallness of neutrino masses, neutrino mass hierarchy, the mechanism responsible for neutrino masses, and the Dirac/Majorana nature of neutrinos.

GENERALIZED FUKUGITA–TANIMOTO–YANAGIDA NEUTRINO MASS ANSATZ

2007 ◽  
Vol 16 (05) ◽  
pp. 1405-1416 ◽  
Author(s):  
MIDORI OBARA ◽  
ZHI-ZHONG XING
Keyword(s):  
Beta Decay ◽  
Neutrinoless Double Beta Decay ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Mixing Angles ◽  
Effective Masses ◽  
Majorana Neutrinos ◽  
Mass Degeneracy ◽  
The Masses

We generalize the Fukugita–Tanimoto–Yanagida ansatz by allowing the masses of three heavy right-handed Majorana neutrinos, Mi (i = 1,2,3), to be partially non-degenerate and search for the parameter space which can be consistent with the current neutrino oscillation data, for three non-degenerate mass cases (A) M3 = M2 ≠ M1, (B) M2 = M1 ≠ M3 and (C) M1 = M3 ≠ M2. We also examine the effect of the deviation from the complete mass degeneracy in each case. Finally, we obtain the numerical constraints on three light neutrino masses, three neutrino mixing angles and three CP-violating phases, together with the predictions for the Jarlskog invariant of CP violation and the effective masses of the tritium beta decay and the neutrinoless double-beta decay.

Neutrino Masses and Mixings

2019 ◽  
pp. 313-326
Author(s):  
Michael E. Peskin
Keyword(s):  
Experimental Determination ◽  
Neutrino Mass ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Neutrino Flavor ◽  
Flavor Mixing ◽  
Pmns Matrix ◽  
The Masses ◽  
Neutrino Masses And Mixings

This chapter discusses the search for and eventual discovery of the masses of neutrinos. It explains that observability of neutrino mass depends on neutrino flavor mixing. It introduces the PMNS matrix describing neutrino mixing and describes the experimental determination of the parameters of this matrix.

Neutrino masses from modified bimaximal mixing

2015 ◽  
Vol 30 (32) ◽  
pp. 1550169
Author(s):  
Asan Damanik
Keyword(s):  
Neutrino Mass ◽  
Mass Matrix ◽  
Mass Difference ◽  
Atmospheric Neutrino ◽  
Double Beta Decay ◽  
Neutrino Mass Matrix ◽  
Experimental Results ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Mixing Matrix

The bimaximal (BM) neutrino mixing matrix was formulated in order to accommodate the data of the experimental results which indicate that both solar and atmospheric neutrino oscillation in vacuum are near maximal. But, after the T2K and Daya Bay Collaborations reported that the mixing angle [Formula: see text] is nonzero and relatively large, many authors have modified the neutrino mixing matrix in order to accommodate experimental data. We modified the BM mixing matrix by introducing a simple perturbation matrix into BM mixing matrix. The modified BM mixing matrix can proceed the mixing angles which are compatible with the global fit analysis data and by imposing the [Formula: see text]–[Formula: see text] symmetry into mass matrix from modified BM, we have the neutrino mass in normal hierarchy (NH): [Formula: see text]. Using the neutrino masses that obtained from neutrino mass matrix in the scheme of modified BM and imposing the constraint exact [Formula: see text] symmetry into neutrino mass matrix, we cannot have compatible squared-mass differences for both [Formula: see text] and [Formula: see text] as dictated by experimental results. In order to proceed the neutrino masses that can predict correctly the squared-mass difference, we introduce a small parameter [Formula: see text] into neutrino mass matrix. The obtained neutrino masses are in agreement with the squared-mass difference as dictated by experimental results. The predicted neutrino effective mass: [Formula: see text] in this paper can be tested in the future neutrinoless double beta decay.

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 CONSTRAINTS OF MIXING ANGLES FROM LEPTON NUMBER VIOLATING PROCESSES

1999 ◽  
Vol 14 (06) ◽  
pp. 433-445 ◽  
Author(s):  
HIROYUKI NISHIURA ◽  
KOUICHI MATSUDA ◽  
TAKESHI FUKUYAMA
Keyword(s):  
Beta Decay ◽  
Neutrinoless Double Beta Decay ◽  
Lepton Number ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Mixing Angles ◽  
Left Handed ◽  
Majorana Neutrinos ◽  
Mixing Matrix ◽  
Lepton Number Violating

We discuss the constraints of lepton mixing angles from lepton number violating processes such as neutrinoless double beta decay, μ--e+ conversion and K decay, K-→π+μ-μ- which are allowed only if neutrinos are Majorana particles. The rates of these processes are proportional to the averaged neutrino mass defined by [Formula: see text] in the absence of right-handed weak coupling. Here a, b(j) are flavor(mass) eigenstates and Uaj is the left-handed lepton mixing matrix. We give general conditions imposed on <mν>ab in terms of mi, lepton mixing angles and CP violating phases (three phases in Majorana neutrinos). These conditions are reduced to the constraints among mi, lepton mixing angles and <mν>ab which are irrelevant to the concrete values of CP phases. Given a <mν>ab experimentally, these conditions constrain mi and the lepton mixing angles. Though these constraints are still loose except for neutrinoless double beta decay, they will become helpful through rapid improvements of experiments. By using these constraints we also derive the limits on averaged neutrino masses for μ--e+ conversion and K decay, K-→π+μ-μ-, respectively. We also present the bounds for CP phases in terms of mi, mixing angles and <mν>ab.

Avoided-crossing molecular-beam spectroscopy of symmetric tops. I. Phosphoryl fluoride (OPF3)

1981 ◽  
Vol 59 (1) ◽  
pp. 150-171 ◽  
Author(s):  
Irving Ozier ◽  
W. Leo Meert
Keyword(s):  
Dipole Moment ◽  
Molecular Beam ◽  
Wave Functions ◽  
Matrix Elements ◽  
Centrifugal Distortion ◽  
Electric Resonance ◽  
Avoided Crossing ◽  
Mixing Matrix ◽  
The Individual

A new avoided-crossing technique using a conventional molecular beam electric resonance spectrometer has been developed for studying symmetric rotors. By means of an external electric field, two levels with different values of K are made nearly degenerate and normally forbidden electric-dipole transitions between the interacting levels are observed. Mixing matrix elements ηST with ΔK = ± 3 arise from the centrifugal distortion dipole moment μD and mixing terms ηHYP, with ΔK = ± 1, ± 2 arise from the nuclear hyperfine Hamiltonian. Explicit expressions for ηHYP are given in an Appendix. Many of these terms break the symmetry of both the rotational and nuclear spin parts of the wave functions. The avoided-crossing method is discussed in detail, with emphasis on its application to the measurement of (A0–B0). It is shown how the technique can be used to determine the perpendicular moment μD, as well as μJ, and μK, the constants which characterize the dependence of the parallel dipole moment μ on J and K, respectively. Other applications include the experimental investigation of the selection rules for the individual terms in ηHYP and the determination of the sign of the rotational g-factors [Formula: see text] and [Formula: see text].∙The method has been applied to phosphoryl fluoride (OPF3). It has been determined that (A0–B0) = 217.4987(44) MHz, μD = 5.856(20) × 10−6 D, μJ = −3.38(10) × 10−6 D, and both [Formula: see text] and [Formula: see text] are negative.

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