scholarly journals IMPLICATIONS OF QUARK–LEPTON SYMMETRY FOR NEUTRINO MASSES AND OSCILLATIONS

2000 ◽  
Vol 15 (06) ◽  
pp. 439-443 ◽  
Author(s):  
T. GOLDMAN ◽  
G. J. STEPHENSON ◽  
B. H. J. McKELLAR
Keyword(s):  
Model Prediction ◽  
Neutral Current ◽  
Charged Current ◽  
Solar Model ◽  
Neutrino Masses ◽  
Current Signal ◽  
Standard Solar Model ◽  
Sterile Neutrinos ◽  
Long Baseline ◽  
Flavor Mixing

We identify a plausible scenario based on quark–lepton symmetry which correlates long baseline oscillations with maximal mixing to sterile neutrinos. The implication for the Sudbury Neutrino Observatory (SNO) is that the neutral current signal will be found to suffer the same suppression from the standard solar model prediction as obtains for the charged current signal. Flavor mixing among active neutrinos is expected to occur on shorter baselines with smaller mixing amplitudes.

scholarly journals Standard versus non-standard CP phases in neutrino oscillation in matter with non-unitarity

2020 ◽  
Vol 2020 (6) ◽  
Author(s):  
Ivan Martinez-Soler ◽  
Hisakazu Minakata
Keyword(s):  
Neutral Current ◽  
Phase Correlation ◽  
Charged Current ◽  
Unitary Matrix ◽  
Particle Data Group ◽  
Unitary Evolution ◽  
First Order ◽  
Flavor Mixing ◽  
Mixing Matrix ◽  
Data Group

Abstract We formulate a perturbative framework for the flavor transformation of the standard active three neutrinos but with a non-unitary flavor mixing matrix, a system which may be relevant for the leptonic unitarity test. We use the $\alpha$ parametrization of the non-unitary matrix and take its elements $\alpha_{\beta \gamma}$ ($\beta,\gamma = e,\mu,\tau$) and the ratio $\epsilon \simeq \Delta m^2_{21} / \Delta m^2_{31}$ as the small expansion parameters. Two qualitatively new features that hold in all the oscillation channels are uncovered in the probability formula obtained to first order in the expansion: (1) The phases of the complex $\alpha$ elements always come into the observable in the particular combination with the $\nu$SM CP phase $\delta$ in the form $[e^{- i \delta } \bar{\alpha}_{\mu e}, ~e^{ - i \delta} \bar{\alpha}_{\tau e}, ~\bar{\alpha}_{\tau \mu}]$ under the Particle Data Group convention of a unitary $\nu$SM mixing matrix. (2) The diagonal $\alpha$ parameters appear in particular combinations $\left( a/b - 1 \right) \alpha_{ee} + \alpha_{\mu \mu}$ and $\alpha_{\mu \mu} - \alpha_{\tau \tau}$, where $a$ and $b$ denote, respectively, the matter potential due to charged current and neutral current reactions. This property holds only in the unitary evolution part of the probability, and there is no such feature in the genuine non-unitary part, while the $\delta$–$\alpha$ parameter phase correlation exists for both. The reason for such remarkable stability of the phase correlation is discussed.

scholarly journals STERILE NEUTRINO PRODUCTION THROUGH A MATTER EFFECT ENHANCEMENT AT LONG BASELINES

2013 ◽  
Vol 28 (16) ◽  
pp. 1350067 ◽  
Author(s):  
JOSEPH BRAMANTE
Keyword(s):  
Standard Model ◽  
Sterile Neutrino ◽  
Neutral Current ◽  
Sterile Neutrinos ◽  
Vector Coupling ◽  
Neutrino Production ◽  
Long Baseline ◽  
Current Events ◽  
Matter Effect ◽  
Long Baselines

If sterile neutrinos have a neutral coupling to standard model fermions, matter effect resonant transitions to sterile neutrinos and excess neutral-current events could manifest at long baseline experiments. Assuming a single sterile neutrino with a neutral coupling to fermionic matter, we re-examine bounds on sterile neutrino production at long baselines from the MINOS result Pνμ →νs < 0.22 (90% CL). We demonstrate that sterile neutrinos with a neutral vector coupling to fermionic matter could evade the MINOS limit, allowing a higher fraction of active to sterile neutrino conversion at long baselines. Scanning the parameter space of sterile neutrino matter effect fits of the LSND and MiniBooNe data, we show that in the case of a vector singlet coupling of sterile neutrinos to matter, some favored parametrizations of these fits would create neutral-current event excesses above standard model predictions at long baseline experiments (e.g. MINOS and OPERA).

scholarly journals Low-scale minimal linear seesaw model for neutrino mass and flavor mixing

2021 ◽  
pp. 2150159
Author(s):  
Ernesto A. Matute
Keyword(s):  
Sterile Neutrino ◽  
Small Mass ◽  
The Other ◽  
Neutrino Masses ◽  
High Scale ◽  
Sterile Neutrinos ◽  
The Standard Model ◽  
Low Energies ◽  
Flavor Mixing ◽  
Mass Terms

We consider an extension of the Standard Model with three right-handed (RH) neutrinos and a Dirac pair of extra sterile neutrinos, odd under a discrete [Formula: see text] symmetry, in order to have left–right symmetry in the neutrino content and obtain tiny neutrino masses from the latter ones only. Our working hypothesis is that the heavy RH neutrinos do not influence phenomenology at low energies. We use the usual high-scale seesaw to suppress all of the mass terms involving RH neutrinos and a low-scale minimal variant of the linear seesaw led by the Dirac mass of the extra sterile neutrinos to provide the small mass of active neutrinos. One of the active neutrinos is massless, which fixes the mass of the other two on the basis of a soft breaking of the [Formula: see text] symmetry. The mixing between the extra neutrinos makes for a particle that effectively behaves like a Dirac sterile neutrino with mass around the GeV level.

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 Structure of flavor changing Goldstone boson interactions

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Jin Sun ◽  
Yu Cheng ◽  
Xiao-Gang He
Keyword(s):  
Symmetry Breaking ◽  
Model Building ◽  
Neutral Current ◽  
Goldstone Boson ◽  
New Physics ◽  
Majorana Neutrino ◽  
Neutrino Masses ◽  
Type I ◽  
Flavor Changing ◽  
Flavor Changing Neutral Current

Abstract General flavor changing Goldstone boson (GB) interactions with fermions from a spontaneous global U(1)G symmetry breaking are discussed. This GB may be the Axion, solving the strong QCD CP problem, if there is a QCD anomaly for the assignments of quarks U(1)G charge. Or it may be the Majoron, producing seesaw Majorana neutrino masses by lepton number violation, if the symmetry breaking scale is much higher than the electroweak scale. It may also, in principle, play the roles of Axion and Majoron simultaneously as far as providing solution for the strong CP problem and generating a small Majorana neutrino masses are concerned. Great attentions have been focused on flavor conserving GB interactions. Recently flavor changing Axion and Majoron models have been studied in the hope to find new physics from rare decays in the intensity frontier. In this work, we will provide a systematic model building aspect study for flavor changing neutral current (FCNC) GB interactions in the fermion sectors, or separately in the quark, charged lepton and neutrino sectors and will identify in detail the sources of FCNC interactions in a class of beyond standard model with a spontaneous global U(1)G symmetry breaking. We also provide a general proof of the equivalence of using physical GB components and GB broken generators for calculating GB couplings to two gluons and two photons, and discuss some issues related to spontaneous CP violation models. Besides, we will also provide some details for obtaining FCNC GB interactions in several popular models, such as the Type-I, -II, -III seesaw and Left-Right symmetric models, and point out some special features in these models.

scholarly journals Lowering the scale of Pati-Salam breaking through seesaw mixing

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Matthew J. Dolan ◽  
Tomasz P. Dutka ◽  
Raymond R. Volkas
Keyword(s):  
Degrees Of Freedom ◽  
Tree Level ◽  
Charged Current ◽  
Meson Decay ◽  
Neutrino Masses ◽  
Down Quark ◽  
The Standard Model ◽  
Decay Widths ◽  
Left And Right ◽  
Charged Leptons

Abstract We analyse the experimental limits on the breaking scale of Pati-Salam extensions of the Standard Model. These arise from the experimental limits on rare-meson decay processes mediated at tree-level by the vector leptoquark in the model. This leptoquark ordinarily couples to both left- and right-handed SM fermions and therefore the meson decays do not experience a helicity suppression. We find that the current limits vary from $$ \mathcal{O} $$ O (80–2500) TeV depending on the choice of matrix structure appearing in the relevant three-generational charged-current interactions. We extensively analyse scenarios where additional fermionic degrees of freedom are introduced, transforming as complete Pati-Salam multiplets. These can lower the scales of Pati-Salam breaking through mass-mixing within the charged-lepton and down-quark sectors, leading to a helicity suppression of the meson decay widths which constrain Pati-Salam breaking. We find four multiplets with varying degrees of viability for this purpose: an SU(2)L/R bidoublet, a pair of SU(4) decuplets and either an SU(2)L or SU(2)R triplet all of which contain heavy exotic versions of the SM charged leptons. We find that the Pati-Salam limits can be as low as $$ \mathcal{O} $$ O (5–150) TeV with the addition of these four multiplets. We also identify an interesting possible connection between the smallness of the neutrino masses and a helicity suppression of the Pati-Salam limits for three of the four multiplets.

NEUTRINO MASSES, OSCILLATIONS, AND TESTS WITH FUTURE SUPERBEAMS AND A NEUTRINO FACTORY

2003 ◽  
Vol 18 (22) ◽  
pp. 3921-3933 ◽  
Author(s):  
M. LINDNER
Keyword(s):  
Cp Violation ◽  
Neutrino Oscillation ◽  
Neutrino Masses ◽  
Neutrino Factory ◽  
Mixing Angles ◽  
Long Baseline

Future long baseline neutrino oscillation (LBL) setups are discussed and the remarkable potential for very precise measurements of mass splittings, mixing angles, MSW effects, the sign of Δm2 and leptonic CP violation is shown. Furthermore we discuss the sensitivity improvements which can be obatined by combining the planned JHF-Superkamiokande and the proposed NuMI off-axis experiment.

scholarly journals Flavor Mixing, Neutrino Masses and Neutrino Oscillations

2009 ◽  
Author(s):  
H. Fritzsch ◽  
Vladimir Lebedev ◽  
Mikhail Feigel’man
Keyword(s):  
Neutrino Oscillations ◽  
Neutrino Masses ◽  
Flavor Mixing
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