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.

scholarly journals Inverted neutrino mass hierarchy and mixing in the Zee-Babu model

2016 ◽  
Vol 25 (4) ◽  
pp. 291
Author(s):  
Vo Van Vien ◽  
Hoang Ngoc Long ◽  
Phan Ngoc Thu
Keyword(s):  
Cp Violation ◽  
Effective Mass ◽  
Beta Decay ◽  
Neutrino Mass ◽  
Mass Matrix ◽  
Double Beta Decay ◽  
Recent Analysis ◽  
Neutrino Masses ◽  
Mass Hierarchy ◽  
Neutrino Mass Hierarchy

We show that the neutrino mass matrix of the Zee-Babu model isable to fit the recent data on neutrino masses and mixingwith non-zero $\theta_{13}$ in the inverted neutrino mass hierarchy. The results show that the Majorana  phases are equal to zero and the Dirac phase ($\de$) ispredicted to either $0$ or $\pi$, i. e, there is no CP violation in the Zee-Babu model at the two loop level. The effective mass governingneutrinoless double beta decay and the sum of neutrino masses areconsistent with the recent analysis.

scholarly journals Physics Potential of Long-Baseline Experiments

2014 ◽  
Vol 2014 ◽  
pp. 1-29 ◽  
Author(s):  
Sanjib Kumar Agarwalla
Keyword(s):  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
New Physics ◽  
Mass Hierarchy ◽  
Neutrino Mixing ◽  
Neutrino Mass Hierarchy ◽  
Mixing Angle ◽  
Long Baseline ◽  
Physics Potential ◽  
Flavor Oscillation

The discovery of neutrino mixing and oscillations over the past decade provides firm evidence for new physics beyond the Standard Model. Recently,θ13has been determined to be moderately large, quite close to its previous upper bound. This represents a significant milestone in establishing the three-flavor oscillation picture of neutrinos. It has opened up exciting prospects for current and future long-baseline neutrino oscillation experiments towards addressing the remaining fundamental questions, in particular the type of the neutrino mass hierarchy and the possible presence of a CP-violating phase. Another recent and crucial development is the indication of non-maximal 2-3 mixing angle, causing the octant ambiguity ofθ23. In this paper, I will review the phenomenology of long-baseline neutrino oscillations with a special emphasis on sub-leading three-flavor effects, which will play a crucial role in resolving these unknowns. First, I will give a brief description of neutrino oscillation phenomenon. Then, I will discuss our present global understanding of the neutrino mass-mixing parameters and will identify the major unknowns in this sector. After that, I will present the physics reach of current generation long-baseline experiments. Finally, I will conclude with a discussion on the physics capabilities of accelerator-driven possible future long-baseline precision oscillation facilities.

scholarly journals Current Status and Future Prospects of the SNO+ Experiment

2016 ◽  
Vol 2016 ◽  
pp. 1-21 ◽  
Author(s):  
S. Andringa ◽  
E. Arushanova ◽  
S. Asahi ◽  
M. Askins ◽  
D. J. Auty ◽  
...  
Keyword(s):  
Phase I ◽  
Neutrino Mass ◽  
Liquid Scintillator ◽  
Solar Neutrinos ◽  
Double Beta Decay ◽  
Current Status ◽  
Pure Liquid ◽  
Neutrino Experiment ◽  
Mass Hierarchy ◽  
Neutrino Mass Hierarchy

SNO+ is a large liquid scintillator-based experiment located 2 km underground at SNOLAB, Sudbury, Canada. It reuses the Sudbury Neutrino Observatory detector, consisting of a 12 m diameter acrylic vessel which will be filled with about 780 tonnes of ultra-pure liquid scintillator. Designed as a multipurpose neutrino experiment, the primary goal of SNO+ is a search for the neutrinoless double-beta decay (0νββ) of130Te. In Phase I, the detector will be loaded with 0.3% natural tellurium, corresponding to nearly 800 kg of130Te, with an expected effective Majorana neutrino mass sensitivity in the region of 55–133 meV, just above the inverted mass hierarchy. Recently, the possibility of deploying up to ten times more natural tellurium has been investigated, which would enable SNO+ to achieve sensitivity deep into the parameter space for the inverted neutrino mass hierarchy in the future. Additionally, SNO+ aims to measure reactor antineutrino oscillations, low energy solar neutrinos, and geoneutrinos, to be sensitive to supernova neutrinos, and to search for exotic physics. A first phase with the detector filled with water will begin soon, with the scintillator phase expected to start after a few months of water data taking. The0νββPhase I is foreseen for 2017.

scholarly journals Towards determining the neutrino mass hierarchy: weak lensing and galaxy clustering forecasts with baryons and intrinsic alignments

2020 ◽  
Vol 493 (2) ◽  
pp. 1640-1661 ◽  
Author(s):  
David Copeland ◽  
Andy Taylor ◽  
Alex Hall
Keyword(s):  
Neutrino Mass ◽  
Stage Iv ◽  
Double Beta Decay ◽  
Weak Lensing ◽  
Small Scale ◽  
Mass Hierarchy ◽  
Neutrino Mass Hierarchy ◽  
Galaxy Clustering ◽  
The Impact ◽  
Adiabatic Contraction

ABSTRACT The capacity of Stage IV lensing surveys to measure the neutrino mass sum and differentiate between the normal and inverted mass hierarchies depends on the impact of nuisance parameters describing small-scale baryonic astrophysics and intrinsic alignments. For a Euclid-like survey, we perform the first combined weak lensing and galaxy clustering Fisher analysis with baryons, intrinsic alignments, and massive neutrinos for both hierarchies. We use a matter power spectrum generated from a halo model that captures the impact of baryonic feedback and adiabatic contraction. For weak lensing, we find that baryons cause severe degradation to forecasts of the neutrino mass sum, Σ, approximately doubling σΣ. We show that including galaxy clustering constraints from Euclid and BOSS, and cosmic microwave background (CMB) Planck priors, can reduce this degradation to σΣ to 9 per cent and 16 per cent for the normal and inverted hierarchies, respectively. The combined forecasts, $\sigma _{\Sigma _{\rm {NH}}}=0.034\, \rm {eV}$ and $\sigma _{\Sigma _{\rm {IH}}}=0.034\, \rm {eV}$, preclude a meaningful distinction of the hierarchies but could be improved upon with future CMB priors on ns and information from neutrinoless double beta decay to achieve a 2σ distinction. The effect of intrinsic alignments on forecasts is shown to be minimal, with σΣ even experiencing mild improvements due to information from the intrinsic alignment signal. We find that while adiabatic contraction and intrinsic alignments will require careful calibration to prevent significant biasing of Σ, there is less risk presented by feedback from energetic events like AGN and supernovae.

scholarly journals The SO(10)-inspired leptogenesis timely opportunity

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Pasquale Di Bari ◽  
Rome Samanta
Keyword(s):  
Beta Decay ◽  
Neutrino Mass ◽  
Lower Bounds ◽  
Neutrinoless Double Beta Decay ◽  
Mass Scale ◽  
Double Beta Decay ◽  
Neutrino Masses ◽  
Neutrino Mixing ◽  
Mixing Parameters ◽  
Absolute Neutrino Mass

Abstract We study the connection between absolute neutrino mass and neutrino mixing parameters within SO(10)-inspired leptogenesis. We show that current favoured values of the unknown neutrino mixing parameters point toward values of the absolute neutrino mass scale that will be fully tested by cosmological observations and neutrinoless double beta decay experiments during next years. In particular, for mD2/mcharm≤ 5, where mD2 is the intermediate Dirac neutrino mass, and for current best fit values of the Dirac phase δ and the atmospheric mixing angle θ23, we derive a lower bound on the neutrinoless double beta decay effective neutrino mass mee ≳ 31 meV and on the sum of the neutrino masses Σimi ≳ 125 meV. These lower bounds hold for normally ordered neutrino masses, as currently favoured by global analyses, and approximately for δ ∈ [155°, 240°] and θ23 in the second octant. If values in this region will be confirmed by future planned long baseline experiments, then a signal at next generation neutrinoless double beta decay experiments is expected, despite neutrino masses being normally ordered. Outside the region, the lower bounds strongly relax but a great fraction of the allowed range of values still allows a measurement of the lightest neutrino mass. Therefore, in the next years low energy neutrino experiments will provide a stringent test of SO(10)-inspired leptogenesis, that might result either in severe constraints or in a strong evidence.

scholarly journals Potential impact of sub-structure on the determination of neutrino mass hierarchy at medium-baseline reactor neutrino oscillation experiments

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Zhaokan Cheng ◽  
Neill Raper ◽  
Wei Wang ◽  
Chan Fai Wong ◽  
Jingbo Zhang
Keyword(s):  
Fine Structure ◽  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
Energy Resolution ◽  
Percent Level ◽  
Mass Hierarchy ◽  
Neutrino Mixing ◽  
Near Detector ◽  
Reactor Neutrino ◽  
The Impact

AbstractIn the past decade, the precise measurement of the lastly known neutrino mixing angle $$\theta _{13}$$ θ 13 has enabled the resolution of neutrino mass hierarch (MH) at medium-baseline reactor neutrino oscillation (MBRO) experiments. Recent calculations of the reactor neutrino flux predict percent-level sub-structures in the $$\bar{\nu }_e$$ ν ¯ e spectrum due to Coulomb effects in beta decay. Such fine structure in the reactor spectrum has been an issue of concern for efforts to determine the neutrino MH for the MBRO approach, the concern being that the sub-dominant oscillation pattern used to discriminate different hierarchies will be obscured by fine structure. The energy resolutions of current reactor experiments are not sufficient to measure such fine structure, and therefore the size and location in energy of these predicted discontinuities has not been confirmed experimentally. There has been speculation that a near detector is required with sufficient energy resolution to resolve the fine structure. This article studies the impact of fine structure on the resolution of MH, based on predicted reactor neutrino spectra, using the measured spectrum from Daya Bay as a reference. We also investigate how a near detector could improve the sensitivity of neutrino MH resolution based on various assumptions of near detector energy resolution.

scholarly journals Some uncertainties of neutrino oscillation effect in the NOνA experiment

2016 ◽  
Vol 31 (12) ◽  
pp. 1650077 ◽  
Author(s):  
Lyudmila D. Kolupaeva ◽  
Konstantin S. Kuzmin ◽  
Olga N. Petrova ◽  
Igor M. Shandrov
Keyword(s):  
Neutrino Oscillation ◽  
Neutrino Mass ◽  
Cross Sections ◽  
Forward Scattering ◽  
Mass Hierarchy ◽  
Neutrino Mass Hierarchy ◽  
Oscillation Effect ◽  
Neutrino Scattering ◽  
The Cross ◽  
Nuclear Targets

Uncertainties related to the effect of neutrino coherent forward scattering in Earth’s matter (MSW mechanism) and with the cross-sections of quasi-elastic (QE) neutrino scattering on nuclear targets of the NO[Formula: see text]A detectors are studied. The NO[Formula: see text]A sensitivity to the neutrino mass hierarchy and the CP violating phase is discussed.

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