13. Neutrino mixing 1 13. NEUTRINO MASS, MIXING, AND OSCILLATIONS
13. Neutrino mixing 1 13. NEUTRINO MASS, MIXING, AND OSCILLATIONS Updated October 2011 by K compelling evidences for oscillations of neutrinos caused by nonzero neutrino masses and neutrino mixing. The data imply the existence of 3-neutrino mixing in vacuum. We review the theory of neutrino oscillations
13. Neutrino mixing 1 13. NEUTRINO MASS, MIXING, AND OSCILLATIONS
13. Neutrino mixing 1 13. NEUTRINO MASS, MIXING, AND OSCILLATIONS Written May 2010 by K. Nakamura for oscillations of neutrinos caused by nonzero neutrino masses and neutrino mixing. The data imply the existence of 3-neutrino mixing in vacuum. We review the theory of neutrino oscillations, the phenomenology
13. Neutrino mixing 1 13. NEUTRINO MASS, MIXING, AND OSCILLATIONS
13. Neutrino mixing 1 13. NEUTRINO MASS, MIXING, AND OSCILLATIONS Updated May 2012 by K. Nakamura have provided compelling evidences for oscillations of neutrinos caused by nonzero neutrino masses of neutrino oscillations, the phenomenology of neutrino mixing, the problem of the nature - Dirac or Majorana
Mass hierarchies and the seesaw neutrino mixing
Kuo, T. K. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States)] [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Wu, Guo-Hong [Institute of Theoretical Science, University of Oregon, Eugene, Oregon 97403 (United States)] [Institute of Theoretical Science, University of Oregon, Eugene, Oregon 97403 (United States); Mansour, Sadek W. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States)] [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States)
2000-06-01T23:59:59.000Z
We give a general analysis of neutrino mixing in the seesaw mechanism with three flavors. Assuming that the Dirac and u-quark mass matrices are similar, we establish simple relations between the neutrino parameters and individual Majorana masses. They are shown to depend rather strongly on the physical neutrino mixing angles. We calculate explicitly the implied Majorana mass hierarchies for parameter sets corresponding to different solutions to the solar neutrino problem. (c) 2000 The American Physical Society.
Phenomenological relations for neutrino masses and mixing parameters
Khruschov, V. V., E-mail: khru@imp.kiae.ru [National Research Center Kurchatov Institute (Russian Federation)
2013-11-15T23:59:59.000Z
Phenomenological relations for masses, angles, and CP phases in the neutrino mixing matrix are proposed with allowance for available experimental data. For the case of CP violation in the lepton sector, an analysis of the possible structure of the neutrino mass matrix and a calculation of the neutrino mass features and the Dirac CP phase for the bimodal-neutrino model are performed. The values obtained in this way can be used to interpret and predict the results of various neutrino experiments.
Carlo Giunti; Marco Laveder
2004-10-01T23:59:59.000Z
In this review we present the main features of the current status of neutrino physics. After a review of the theory of neutrino mixing and oscillations, we discuss the current status of solar and atmospheric neutrino oscillation experiments. We show that the current data can be nicely accommodated in the framework of three-neutrino mixing. We discuss also the problem of the determination of the absolute neutrino mass scale through Tritium beta-decay experiments and astrophysical observations, and the exploration of the Majorana nature of massive neutrinos through neutrinoless double-beta decay experiments. Finally, future prospects are briefly discussed.
Models of Neutrino Mass, Mixing and CP Violation
Stephen F. King
2015-10-07T23:59:59.000Z
In this topical review we argue that neutrino mass and mixing data motivates extending the Standard Model to include a non-Abelian discrete flavour symmetry in order to accurately predict the large leptonic mixing angles and CP violation. We begin with an overview of the Standard Model puzzles, followed by a description of some classic lepton mixing patterns. Lepton mixing may be regarded as a deviation from tri-bimaximal mixing, with charged lepton corrections leading to solar mixing sum rules, or tri-maximal lepton mixing leading to atmospheric mixing rules. We survey neutrino mass models, using a roadmap based on the open questions in neutrino physics. We then focus on the seesaw mechanism with right-handed neutrinos, where sequential dominance (SD) can account for large lepton mixing angles and CP violation, with precise predictions emerging from constrained SD (CSD). We define the flavour problem and discuss progress towards a theory of flavour using GUTs and discrete family symmetry. We classify models as direct, semidirect or indirect, according to the relation between the Klein symmetry of the mass matrices and the discrete family symmetry, in all cases focussing on spontaneous CP violation. Finally we give two examples of realistic and highly predictive indirect models with CSD, namely an A to Z of flavour with Pati-Salam and a fairly complete $A_4\\times SU(5)$ SUSY GUT of flavour, where both models have interesting implications for leptogenesis.
Near Maximal Atmospheric Neutrino Mixing in Neutrino Mass Models with Two Texture Zeros
S. Dev; Radha Raman Gautam; Lal Singh; Manmohan Gupta
2014-08-05T23:59:59.000Z
The implications of a large value of the effective Majorana neutrino mass for a class of two texture zero neutrino mass matrices have been studied in the flavor basis. It is found that these textures predict near maximal atmospheric neutrino mixing angle in the limit of large effective Majorana neutrino mass. It is noted that this prediction is independent of the values of solar and reactor neutrino mixing angles. We present the symmetry realization of these textures using the discrete cyclic group $Z_3$. It is found that the texture zeros realised in this work remain stable under renormalization group running of the neutrino mass matrix from the seesaw scale to the electroweak scale, at one loop level.
Sterile neutrinos: direct mixing effects versus induced mass matrix of active neutrinos
Alexei Yu. Smirnov; Renata Zukanovich Funchal
2006-06-14T23:59:59.000Z
Mixing of active neutrinos with sterile ones generate ``induced'' contributions to the mass matrix of active neutrinos $\\sim m_S \\sin^2\\theta_{aS}$, where $m_S$ is the Majorana mass of the sterile neutrino and $\\theta_{aS}$ is the active-sterile mixing angle. We study possible effects of the induced matrix which can modify substantially the implications of neutrino oscillation results. We have identified the regions of $m_S$ and $\\sin^2\\theta_{aS}$ where the induced matrix (i) provides the dominant structures, (ii) gives the sub-dominant effects and (iii) where its effects can be neglected. The induced matrix can be responsible for peculiar properties of the lepton mixing and neutrino mass spectrum, in particular, it can generate the tri-bimaximal mixing. We update and discuss bounds on the induced masses from laboratory measurements, astrophysics and cosmology. We find that substantial impact of the induced matrix is possible if $m_S \\sim 0.1-1$ eV and $\\sin^2\\theta_{aS} \\sim 10^{-3} - 10^{-2}$ or $m_S \\geq 200$ MeV and $\\sin^2\\theta_{aS} \\leq 10^{-9}$. The bounds can be relaxed in cosmological scenarios with low reheating temperature, if sterile neutrinos decay sufficiently fast, or their masses change with time.
Neutrino masses and mixing, quark-lepton symmetry, and strong right-handed neutrino hierarchy
Dermisek, Radovan [Davis Institute for High Energy Physics, University of California, Davis, California 95616 (United States)
2004-10-01T23:59:59.000Z
Assuming the same form of all mass matrices as motivated by quark-lepton symmetry, we discuss conditions under which bilarge mixing in the lepton sector can be obtained with a minimal amount of fine-tuning requirements for possible models. We assume hierarchical mass matrices, dominated by the 3-3 element, with off-diagonal elements much smaller than the larger neighboring diagonal element. Characteristic features of this scenario are strong hierarchy in masses of right-handed neutrinos, and comparable contributions of both lighter right-handed neutrinos to the resulting left-handed neutrino Majorana mass matrix. Because of obvious quark-lepton symmetry, this approach can be embedded into grand unified theories. The mass of the lightest neutrino does not depend on details of a model in the leading order. The right-handed neutrino scale can be identified with the GUT scale in which case the mass of the lightest neutrino is given as (m{sub top}{sup 2}/M{sub GUT}) vertical bar U{sub {tau}}{sub 1} vertical bar{sup 2}.
Neutrino Mixing Angles from Texture Zeros of the Lepton Mass Matrices
Fritzsch, Harald
2012-01-01T23:59:59.000Z
Taking into account the latest neutrino oscillation data, we study texture zeros of the lepton mass matrices. Assuming the Dirac neutrino mass matrix M_D, the charged-lepton mass matrix M_l and the mass matrix of heavy right-handed Majorana neutrinos M_R to have three texture zeros, we show that the observed neutrino mixing angles can naturally be obtained. The phenomenological implications for the neutrino mass spectrum, the CP-violating phases, the tritium beta decay and the neutrinoless double-beta decay are explored.
Neutrino Mixing Angles from Texture Zeros of the Lepton Mass Matrices
Harald Fritzsch; Shun Zhou
2012-12-03T23:59:59.000Z
Taking into account the latest neutrino oscillation data, we study texture zeros of the lepton mass matrices. Assuming the Dirac neutrino mass matrix M_D, the charged-lepton mass matrix M_l and the mass matrix of heavy right-handed Majorana neutrinos M_R to have three texture zeros, we show that the observed neutrino mixing angles can naturally be obtained. The phenomenological implications for the neutrino mass spectrum, the CP-violating phases, the tritium beta decay and the neutrinoless double-beta decay are explored.
Mahadev Patgiri; N. Nimai Singh
2003-01-29T23:59:59.000Z
An attempt is made to generate the bimaximal mixings of the three species of neutrinos from the textures of the right-handed Majorana neutrino mass matrices. We extend our earlier work in this paper for the generation of the nearly degenerate as well as the inverted hierarchical models of the left-handed Majorana neutrino mass matrices using the non-diagonal textures of the right-handed Majorana neutrino mass matrices and the diagonal form of the Dirac neutrino mass matrices, within the frame work of the seesaw mechanism in a model independent way. Such Majorana neutrino mass models are important to explain the recently reported result on the neutrinoless double beat decay (0/nu/beta/beta) experiment,together with the earlier established data on LMA MSW solar and atmospheric neutrino oscillations.
An SO(10) GUT Model With Lopsided Mass Matrix and Neutrino Mixing Angle theta_13
Xiangdong Ji; Yingchuan Li; R. N. Mohapatra
2005-10-27T23:59:59.000Z
An alternative supersymmetric SO(10) grand unification model with lopsided fermion mass matrices is introduced. It generates a large solar-neutrino-mixing angle through the neutrinos' Dirac mass matrix constrained by the SO(10) group structure, avoiding the fine-tuning required in the Majorana mass matrix of right-handed neutrinos. The model fits well the known data on masses and mixings of quarks and leptons, and predicts a sizable lepton mixing $\\sin^22\\theta_{13}\\simeq 0.074$, which is significantly larger than that of the original lopsided model.
Neutrino Mixing and Masses from a Minimum Principle
Alonso, R; Isidori, G; Maiani, L
2013-01-01T23:59:59.000Z
We analyze the structure of quark and lepton mass matrices under the hypothesis that they are determined from a minimum principle applied to a generic potential invariant under the $[SU(3)]^5\\otimes {\\mathcal O}(3)$ flavor symmetry, acting on Standard Model fermions and right-handed neutrinos. Unlike the quark case, we show that hierarchical masses for charged leptons are naturally accompanied by degenerate Majorana neutrinos with one angle close to maximal, a second potentially large, a third one necessarily small, and precise values for the two Majorana phases. Adding small perturbations the predicted structure for the neutrino mass matrix is in excellent agreement with present observations and could be tested in the near future via neutrino-less double beta decay. The generalization of these results to arbitrary sew-saw models is also discussed.
Thermal and non-thermal leptogenesis in different neutrino mass models with tribimaximal mixings
N. Nimai Singh; H. Zeen Devi; Amal Kr Sarma
2008-07-15T23:59:59.000Z
In the present work we study both thermal and non-thermal leptogenesis in all neutrino mass models describing the presently available neutrino mass patterns. We consider the Majorana CP violating phases coming from right-handed Majorana mass matrices to estimate the baryon asymmetry of the universe, for different neutrino mass models namely degenerate, inverted hierarchical and normal hierarchical models, with tribimaximal mixings. Considering two possible diagonal forms of Dirac neutrino mass matrix as either charged lepton or up-quark mass matrix, the right-handed Majorana mass matrices are constructed from the light neutrino mass matrix through the inverse seesaw formula. Only the normal hierarchical model leads to the best predictions for baryon asymmetry of the universe, consistent with observations in both thermal and non-thermal leptogenesis scenario. The analysis though phenomenological may serve as an additional information in the discrimination among the presently available neutrino mass models.
LSND versus MiniBooNE: Sterile neutrinos with energy dependent masses and mixing?
Thomas Schwetz
2008-01-25T23:59:59.000Z
Standard active--sterile neutrino oscillations do not provide a satisfactory description of the LSND evidence for neutrino oscillations together with the constraints from MiniBooNE and other null-result short-baseline oscillation experiments. However, if the mass or the mixing of the sterile neutrino depends in an exotic way on its energy all data become consistent. I explore the phenomenological consequences of the assumption that either the mass or the mixing scales with the neutrino energy as $1/E_\
Neutrino masses and mixing: a flavour symmetry roadmap
S. Morisi; J. W. F. Valle
2012-06-28T23:59:59.000Z
Over the last ten years tri-bimaximal mixing has played an important role in modeling the flavour problem. We give a short review of the status of flavour symmetry models of neutrino mixing. We concentrate on non-Abelian discrete symmetries, which provide a simple way to account for the TBM pattern. We discuss phenomenological implications such as neutrinoless double beta decay, lepton flavour violation as well as theoretical aspects such as the possibility to explain quarks and leptons within a common framework, such as grand unified models.
Neutrino masses and mixing: a flavour symmetry roadmap
Morisi, S
2012-01-01T23:59:59.000Z
Over the last ten years tri-bimaximal mixing has played an important role in modeling the flavour problem. We give a short review of the status of flavour symmetry models of neutrino mixing. We concentrate on non-Abelian discrete symmetries, which provide a simple way to account for the TBM pattern. We discuss phenomenological implications such as neutrinoless double beta decay, lepton flavour violation as well as theoretical aspects such as the possibility to explain quarks and leptons within a common framework, such as grand unified models.
Double Beta Decay Constraints on Neutrino Masses and Mixing; Reanalysis with KamLAND Data
Hisakazu Minakata; Hiroaki Sugiyama
2003-03-04T23:59:59.000Z
In the light of KamLAND data just released, we reanalyze and update the constraints on neutrino masses and mixing parameters, the most general ones that can be derived in three-flavor mixing scheme of neutrinos with use of the bounds imposed by neutrinoless double beta decay search and reactor experiments. We point out that with KamLAND data and assuming Majorana neutrinos one can derive, for the first time, an upper bound on neutrino contribution to the cosmological \\Omega parameter, \\Omega_{\
Neutrino mass hierarchy and the origin of leptonic flavor mixing from the righthanded sector
Leser, Philipp
2011-01-01T23:59:59.000Z
We consider a neutrino mass model where all leptonic mixing is induced by a heavy Majorana sector through the seesaw type I mechanism, while the Dirac mass matrices are diagonal. Such a pattern occurs naturally in Grand Unified Theories (GUTs). Constraints on the parameters of the models are considered and it is shown that a normal neutrino mass hierarchy is preferred. The lightest neutrino mass is typically small, leading to non-observable rates for neutrinoless double beta decay in the normal hierarchy case.
Tribimaximal mixing in neutrino mass matrices with texture zeros or vanishing minors
Dev, S; Gautam, Radha Raman
2010-01-01T23:59:59.000Z
We study the existence of one/two texture zeros or one/two vanishing minors in the neutrino mass matrix with $\\mu\\tau$ symmetry. In the basis where the charged lepton mass matrix and the Dirac neutrino mass matrix are diagonal, the one/two zeros or one/two vanishing minors in the right-handed Majorana mass matrix having $\\mu\\tau$ symmetry will propagate via seesaw mechanism as one/two vanishing minors or one/two texture zeros in the neutrino mass matrix with $\\mu\\tau$ symmetry respectively. It is found that only five such texture structures of the neutrino mass matrix are phenomenologically viable. For tribimaximal mixing, these texture structures reduce the number of free parameters to one. Interesting predictions are obtained for the effective Majorana mass $M_{ee}$, the absolute mass scale and the Majorana-type CP violating phases.
Tribimaximal mixing in neutrino mass matrices with texture zeros or vanishing minors
S. Dev; Shivani Gupta; Radha Raman Gautam
2010-11-25T23:59:59.000Z
We study the existence of one/two texture zeros or one/two vanishing minors in the neutrino mass matrix with $\\mu\\tau$ symmetry. In the basis where the charged lepton mass matrix and the Dirac neutrino mass matrix are diagonal, the one/two zeros or one/two vanishing minors in the right-handed Majorana mass matrix having $\\mu\\tau$ symmetry will propagate via seesaw mechanism as one/two vanishing minors or one/two texture zeros in the neutrino mass matrix with $\\mu\\tau$ symmetry respectively. It is found that only five such texture structures of the neutrino mass matrix are phenomenologically viable. For tribimaximal mixing, these texture structures reduce the number of free parameters to one. Interesting predictions are obtained for the effective Majorana mass $M_{ee}$, the absolute mass scale and the Majorana-type CP violating phases.
Strobel, E.L.
1985-01-01T23:59:59.000Z
Given the many conflicting experimental results, examination is made of the neutrino mass matrix in order to determine possible masses and mixings. It is assumed that the Dirac mass matrix for the electron, muon, and tau neutrinos is similar in form to those of the quarks and charged leptons, and that the smallness of the observed neutrino masses results from the Gell-Mann-Ramond-Slansky mechanism. Analysis of masses and mixings for the neutrinos is performed using general structures for the Majorana mass matrix. It is shown that if certain tentative experimental results concerning the neutrino masses and mixing angles are confirmed, significant limitations may be placed on the Majorana mass matrix. The most satisfactory simple assumption concerning the Majorana mass matrix is that it is approximately proportional to the Dirac mass matrix. A very recent experimental neutrino mass result and its implications are discussed. Some general properties of matrices with structure similar to the Dirac mass matrices are discussed.
Neutrino Masses, Lepton Flavor Mixing and Leptogenesis in the Minimal Seesaw Model
Wan-lei Guo; Zhi-zhong Xing; Shun Zhou
2006-12-05T23:59:59.000Z
We present a review of neutrino phenomenology in the minimal seesaw model (MSM), an economical and intriguing extension of the Standard Model with only two heavy right-handed Majorana neutrinos. Given current neutrino oscillation data, the MSM can predict the neutrino mass spectrum and constrain the effective masses of the tritium beta decay and the neutrinoless double-beta decay. We outline five distinct schemes to parameterize the neutrino Yukawa-coupling matrix of the MSM. The lepton flavor mixing and baryogenesis via leptogenesis are investigated in some detail by taking account of possible texture zeros of the Dirac neutrino mass matrix. We derive an upper bound on the CP-violating asymmetry in the decay of the lighter right-handed Majorana neutrino. The effects of the renormalization-group evolution on the neutrino mixing parameters are analyzed, and the correlation between the CP-violating phenomena at low and high energies is highlighted. We show that the observed matter-antimatter asymmetry of the Universe can naturally be interpreted through the resonant leptogenesis mechanism at the TeV scale. The lepton-flavor-violating rare decays, such as $\\mu \\to e + \\gamma$, are also discussed in the supersymmetric extension of the MSM.
D. Fargion; D. D'Armiento
2012-03-05T23:59:59.000Z
We tried to fit in any way the recent Opera-Cern claims of a neutrino super-luminal speed with observed Supernova SN1987A neutrino burst and all (or most) neutrino flavor oscillation. We considered three main frame-works: (1) A tachyon imaginary neutrino mass, whose timing is nevertheless in conflict with observed IMB-Kamiokande SN1987A burst by thousands of billion times longer. (2) An ad hoc anti-tachyon model whose timing shrinkage may accommodate SN1987A burst but greatly disagree with energy independent Cern-Opera super-luminal speed. (3) A split neutrino flavor speed (among a common real mass relativistic neutrino electron component and a super-luminal neutrino {\\mu}) in an ad hoc frozen speed scenario that is leading to the prompt neutrino de-coherence and the rapid flavor mixing (between electron and muon ones) that are in conflict with most oscillation records. Therefore we concluded that an error must be hidden in Opera-Cern time calibration (as indeed recent rumors seem to confirm). We are also reminding the relevance of the guaranteed minimal atmospheric neutrino mass whose detection may be achieved by a milliseconds graviton-neutrino split time delay among gravity burst and neutronization neutrino peak in any future SN explosion in Andromeda recordable in Megaton neutrino detector.
Constraints on the tau neutrino mass and mixing from precise measurements of tau decay rates
John Swain; Lucas Taylor
1996-10-04T23:59:59.000Z
We have derived constraints on the tau neutrino mass and fourth generation mixing from an analysis of the partial widths of tau lepton decays, in particular: tau -> e nu nu_tau, tau -> mu nu nu_tau, tau -> pi nu_tau, tau -> K nu_tau. We present predictions for the tau decay widths, allowing for a non-zero tau neutrino mass, m(nu_tau), and for mixing with a neutrino of mass m(nu_L) > M_Z/2, which is parametrised using a Cabibbo-like mixing angle, theta_L. By comparison of these theoretical predictions with the experimental measurements, we obtain the following bounds at the 90% confidence level: m(nu_tau) < 42 MeV and sin^2(theta_L) < 0.014.
Neutrino masses and mixings in a Minimal S3-invariant Extension of the Standard Model
Felix, O.; Mondragon, A.; Mondragon, M.; Peinado, E. [Departamento de Fisica Teorica, Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, 01000 Mexico D.F. (Mexico)
2007-06-19T23:59:59.000Z
The mass matrices of the charged leptons and neutrinos, that had been derived in the framework of a Minimal S3-invariant Extension of the Standard Model, are here reparametrized in terms of their eigenvalues. The neutrino mixing matrix, VPMNS, is then computed and exact, explicit analytical expressions for the neutrino mixing angles as functions of the masses of the neutrinos and charged leptons are obtained. The reactor, {theta}13, and the atmosferic, {theta}23, mixing angles are found to be functions only of the masses of the charged leptons. The numerical values of {theta}{sub 13}{sup th} and {theta}{sub 23}{sup th} computed from our theoretical expressions are found to be in excellent agreement with the latest experimental determinations. The solar mixing angle, {theta}{sub 12}{sup th}, is found to be a function of both, the charged lepton and neutrino masses, as well as of a Majorana phase {phi}{nu}. A comparison of our theoretical expression for the solar angle {theta}{sub 12}{sup th} with the latest experimental value {theta}{sub 13}{sup exp} {approx_equal} 34 deg. allowed us to fix the scale and origin of the neutrino mass spectrum and obtain the mass values |m{nu}2| = 0.0507eV, |m{nu}1| = 0.0499eV and |m{nu}3| = 0.0193eV, in very good agreement with the observations of neutrino oscillations, the bounds extracted from neutrinoless double beta decay and the precision cosmological measurements of the CMB.
Christian Weinheimer; Kai Zuber
2013-09-04T23:59:59.000Z
The various experiments on neutrino oscillation evidenced that neutrinos have indeed non-zero masses but cannot tell us the absolute neutrino mass scale. This scale of neutrino masses is very important for understanding the evolution and the structure formation of the universe as well as for nuclear and particle physics beyond the present Standard Model. Complementary to deducing constraints on the sum of all neutrino masses from cosmological observations two different methods to determine the neutrino mass scale in the laboratory are pursued: the search for neutrinoless double $\\beta$-decay and the direct neutrino mass search by investigating single $\\beta$-decays or electron captures. The former method is not only sensitive to neutrino masses but also probes the Majorana character of neutrinos and thus lepton number violation with high sensitivity. Currently quite a few experiments with different techniques are being constructed, commissioned or are even running, which aim for a sensitivity on the neutrino mass of {\\cal O}(100) meV. The principle methods and these experiments will be discussed in this short review.
Running of Low-Energy Neutrino Masses, Mixing Angles and CP Violation
John Ellis; Andi Hektor; Mario Kadastik; Kristjan Kannike; Martti Raidal
2005-06-13T23:59:59.000Z
We calculate the running of low-energy neutrino parameters from the bottom up, parameterizing the unknown seesaw parameters in terms of the dominance matrix $R$. We find significant running only if the $R$ matrix is non-trivial and the light-neutrino masses are moderately degenerate. If the light-neutrino masses are very hierarchical, the quark-lepton complementarity relation $\\theta_c + \\theta_{12} = \\pi/4$ is quite stable, but $\\theta_{13,23}$ may run beyond their likely future experimental errors. The running of the oscillation phase $\\delta$ is enhanced by the smallness of $\\theta_{13}$, and jumps in the mixing angles occur in cases where the light-neutrino mass eigenstates cross.
Tokyo, University of
1 Neutrino Mass and Mixing Measurements at Super-Kamiokande R. Svoboda (for the Super-Kamiokande-4001 USA The latest atmospheric and solar neutrino measurements from over 1100 live days of the Super-Kamiokande Oscillation (VO) allowed regions from ux de#12;cit alone are excluded at the 95% c:l: 1. The Super-Kamiokande
Zheng-Cheng Gu
2014-03-07T23:59:59.000Z
Recently, Majorana's spirit returns to modern condensed matter physics -- in the context of topological Majorana zero mode that represents a local half degree of freedom carrying non-Abelian statistics.In this paper, we investigate the topological nature of a Majorana fermion by assuming that it is made up of four Majorana zero modes at cutoff energy scale. First, we show that a pair of Majorana zero modes can realize a $T^4=-1$ time reversal symmetry, a $P^4=-1$ parity symmetry and even a nontrivial $\\overline C^4=-1$ charge conjugation symmetry. Next, we propose a $\\overline CPT$ super algebra for the Majorana fermion made up of four Majorana zero modes. Furthermore, the origin of three generations of neutrinos(assuming they are Majorana fermions) can be naturally explained as three distinguishable ways to form a pair of (local) complex fermions out of four Majorana zero modes. Finally, we compute the neutrino mass mixing matrix and mass ratios of the three mass eigenstates from a first principle at leading order(in the absence of $CP$ violation and charged lepton corrections). We obtain $\\theta_{12} =31.7^\\circ$, $\\theta_{23}=45^\\circ$, $\\theta_{13}=0^\\circ$ and $m_1/m_3=m_2/m_3=3/\\sqrt{5}$. We predict the effective mass in neutrinoless double beta decay to be $m_{\\beta\\beta}=m_1/\\sqrt{5}$.
Neutrino Masses in Astroparticle Physics
G. G. Raffelt
2002-08-08T23:59:59.000Z
The case for small neutrino mass differences from atmospheric and solar neutrino oscillation experiments has become compelling, but leaves the overall neutrino mass scale m_nu undetermined. The most restrictive limit of m_nu neutrinos. If solar neutrino oscillations indeed correspond to the favored large mixing angle MSW solution, then big-bang nucleosynthesis gives us a restrictive limit on all neutrino chemical potentials, removing the previous uncertainty of n_nu. Therefore, a possible future measurement of m_nu will directly establish the cosmic neutrino mass fraction Omega_nu. Cosmological neutrinos with sub-eV masses can play an interesting role for producing the highest-energy cosmic rays (Z-burst scenario). Sub-eV masses also relate naturally to leptogenesis scenarios of the cosmic baryon asymmetry. Unfortunately, the time-of-flight dispersion of a galactic or local-group supernova neutrino burst is not sensitive in the sub-eV range.
Neutrino Mixing and Discrete Symmetries
Hu, Bo
2012-01-01T23:59:59.000Z
A model independent study of neutrino mixing based on a new method to derive mixing patterns is presented. An interesting result we find is that, in the case where unbroken residual symmetries of the Majorana neutrino and left-handed charged-lepton mass matrices obey some general assumptions, the complete set of possible mixing patterns can be determined by the solutions to the constraint equation with the help of algebraic number theory. This method can also be applied to more general cases beyond the minimal scenario. Several applications and phenomenological implications are discussed.
Capps, R.H.; Strobel, E.L.
1985-07-01T23:59:59.000Z
It is assumed that the Dirac mass matrix for the neutrinos (..nu../sub e/,..nu../sub ..mu../,..nu../sub tau/) is similar in form to those for the quarks and charged leptons, and that the smallness of the observed ..nu.. masses results from the Gell-Mann--Ramond--Slansky mechanism. It is shown that if certain tentative experimental results concerning the ..nu.. masses and mixing angles are confirmed, significant limitations may be placed on the Majorana mass matrix. The most satisfactory simple assumption concerning the Majorana mass matrix is that it is approximately proportional to the Dirac mass matrix. Some general properties of the Dirac matrices are discussed.
Bounds on the Neutrino Mixing Angles and CP Phase for an SO(10) Model with Lopsided Mass Matrices
Carl H. Albright
2005-07-06T23:59:59.000Z
The bounds on the neutrino mixing angles and CP Dirac phase for an SO(10) model with lopsided mass matrices, arising from the presence of ${\\bf 16}_H$ and $\\bar{\\bf 16}_H$ Higgs representations, are studied by variation of the one real and three unknown complex input parameters for the right-handed Majorana neutrino mass matrix. The scatter plots obtained favor nearly maximal atmospheric neutrino mixing, while the reactor neutrino mixing lies in the range $10^{-5} \\lsim \\sin^2 \\theta_{13} \\lsim 1 \\times 10^{-2}$ with values greater than $10^{-3}$ most densely populated. A rather compelling scenario within the model follows, if we restrict the three unknown complex parameters to their imaginary axes and set two of them equal. We then find the scatter plots are reduced to narrow bands, as the mixing angles and CP phase become highly correlated and predictive. The bounds on the mixing angles and phase then become $0.45 \\lsim \\sin^2 \\theta_{23} \\lsim 0.55$, $0.38 \\lsim \\tan^2 \\theta_{12} \\lsim 0.50$, $0.002 \\lsim \\sin^2 \\theta_{13} \\lsim 0.003$, and $60^\\circ \\lsim \\pm \\delta_{CP} \\lsim 85^\\circ$. Moreover, successful leptogenesis and subsequent baryogenesis are also obtained, with $\\eta_B$ increasing from $(2.7 to 6.3) \\times 10^{-10}$ as $\\sin^2 \\theta_{23}$ increases from 0.45 to 0.55.
Neutrino Masses and Flavor Oscillations
Yifang Wang; Zhi-zhong Xing
2015-04-23T23:59:59.000Z
This essay is intended to provide a brief description of the peculiar properties of neutrinos within and beyond the standard theory of weak interactions. The focus is on the flavor oscillations of massive neutrinos, from which one has achieved some striking knowledge about their mass spectrum and flavor mixing pattern. The experimental prospects towards probing the absolute neutrino mass scale, possible Majorana nature and CP-violating effects will also be addressed.
Neutrino Masses and Flavor Oscillations
Wang, Yifang
2015-01-01T23:59:59.000Z
This essay is intended to provide a brief description of the peculiar properties of neutrinos within and beyond the standard theory of weak interactions. The focus is on the flavor oscillations of massive neutrinos, from which one has achieved some striking knowledge about their mass spectrum and flavor mixing pattern. The experimental prospects towards probing the absolute neutrino mass scale, possible Majorana nature and CP-violating effects will also be addressed.
AN OVERVIEW OF NEUTRINO MASSES AND MIXING IN SO(10) MODELS.
CHEN,M.C.MAHANTHAPPA,K.T.
2003-06-05T23:59:59.000Z
We review in this talk various SUSY SO(10) models. Specifically, we discuss how small neutrino masses are generated in and generic predictions of different SO(10) models. A comparison of the predictions of these models for sin{sup 2} {theta}{sub 13}is given.
Neutrino Oscillations With Recently Measured Sterile-Active Neutrino Mixing Angle
Kisslinger, Leonard S
2014-01-01T23:59:59.000Z
This brief report is an extension of a prediction of neutrino oscillation with a sterile neutrino using parameters of the sterile neutrino mass and mixing angle recently extracted from experiment.
Unveiling neutrino mixing and leptonic CP violation
Mena, Olga; /Fermilab
2005-01-01T23:59:59.000Z
We review the present understanding of neutrino masses and mixings, discussing what are the unknowns in the three family oscillation scenario. Despite the anticipated success coming from the planned long baseline neutrino experiments in unraveling the leptonic mixing sector, there are two important unknowns which may remain obscure: the mixing angle {theta}{sub 13} and the CP-phase {delta}. The measurement of these two parameters has led us to consider the combination of superbeams and neutrino factories as the key to unveil the neutrino oscillation picture.
Constraints on absolute neutrino Majorana mass from current data
Huang, Yanqi
2014-01-01T23:59:59.000Z
We present new constraints on the neutrino Majorana masses from the current data of neutrinoless double beta decay and neutrino flavour mixing. With the latest results of $0\
Lyuboshitz, V. L.; Lyuboshitz, V. V., E-mail: Valery.Lyuboshitz@jinr.ru [Joint Institute for Nuclear Research (Russian Federation)
2013-08-15T23:59:59.000Z
The lepton-charge (L{sub e}, L{sub {mu}}, L{sub {tau}}) nonconserving interaction leads to the mixing of the electron, muon, and tau neutrinos, which manifests itself in spatial oscillations of a neutrino beam, and also to the mixing of the electron, negative muon, and tau lepton, which, in particular, may be the cause of the 'forbidden' radiative decay of the negative muon into the electron and {gamma} quantum. Under the assumption that the nondiagonal elements of the mass matrices for neutrinos and ordinary leptons, connected with the lepton charge nonconservation, are the same, and by performing the joint analysis of the experimental data on neutrino oscillations and experimental restriction for the probability of the decay Micro-Sign {sup -} {yields} e{sup -} + {gamma} per unit time, the following estimate for the lower bound of neutrino mass has been obtained: m{sup ({nu})} > 1.5 eV/c{sup 2}.
Neutrino mixing based on mass matrices with a 2{r_reversible}3 symmetry
Koide, Yoshio; Takasugi, Eiichi [Institute for Higher Education Research and Practice, Osaka University, 1-16 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan)
2008-01-01T23:59:59.000Z
Under an assumption that the 2{r_reversible}3 symmetry is broken only through phases, we give a systematic investigation of possible lepton mass matrix forms without referring to explicit parameter values. Two types of the 2{r_reversible}3 symmetry are investigated: one is that the left- and right-handed fields (f{sub L},f{sub R}) obey the symmetry, and another one is that only f{sub L} obeys the symmetry. In the latter case, in spite of no 2{r_reversible}3 symmetry in the Majorana mass matrix M{sub R} for {nu}{sub R}, the neutrino seesaw mass matrix still obeys the 2{r_reversible}3 symmetry. Possible phenomenology is discussed.
Lepton Mass Hierarchy and Neutrino Oscillations
H. Fritzsch; Z. Z Xing
1995-09-26T23:59:59.000Z
Starting from the symmetry of lepton flavor democracy, we propose and discuss a simple pattern for the mass generation and flavor mixing of the charged leptons and neutrinos. The three neutrino masses are nearly degenerate, and the flavor mixing angles can be calculated. The observed deficit of solar and atmospheric neutrinos can be interpreted as a consequence of the near degeneracy and large oscillations of $\
Double Beta Decay and the Absolute Neutrino Mass Scale
Carlo Giunti
2003-08-20T23:59:59.000Z
After a short review of the current status of three-neutrino mixing, the implications for the values of neutrino masses are discussed. The bounds on the absolute scale of neutrino masses from Tritium beta-decay and cosmological data are reviewed. Finally, we discuss the implications of three-neutrino mixing for neutrinoless double-beta decay.
Minimal Schemes for Large Neutrino Mixings with Inverted Hierarchy
Duane A. Dicus; Hong-Jian He; John N. Ng
2002-05-17T23:59:59.000Z
Existing oscillation data point to nonzero neutrino masses with large mixings. We analyze the generic features of the neutrino Majorana mass matrix with inverted hierarchy and construct realistic {\\it minimal schemes} for the neutrino mass matrix that can explain the large (but not maximal) \
Hernandez-Galeana, Albino [Departamento de Fisica de la Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, U.P. Adolfo Lopez Mateos, C.P. 07738. Mexico D.F. (Mexico)
2007-11-01T23:59:59.000Z
I report the analysis performed on fermion masses and mixing, including neutrino mixing, within the context of a model with hierarchical radiative mass generation mechanism for light charged fermions, mediated by exotic scalar particles at one and two loops, respectively, meanwhile the neutrinos get Majorana mass terms at tree level through the Yukawa couplings with two SU(2){sub L} Higgs triplets. All the resulting mass matrices in the model, for the u, d, and e fermion charged sectors, the neutrinos and the exotic scalar particles, are diagonalized in exact analytical form. Quantitative analysis shows that this model is successful to accommodate the hierarchical spectrum of masses and mixing in the quark sector as well as the charged lepton masses. The lepton mixing matrix, V{sub PMNS}, is written completely in terms of the neutrino masses m{sub 1}, m{sub 2}, and m{sub 3}. Large lepton mixing for {theta}{sub 12} and {theta}{sub 23} is predicted in the range of values 0.7 < or approx. sin{sup 2}2{theta}{sub 12} < or approx. 0.7772 and 0.87 < or approx. sin{sup 2}2{theta}{sub 23} < or approx. 0.9023 by using 0.033 < or approx. s{sub 13}{sup 2} < or approx. 0.04. These values for lepton mixing are consistent with 3{sigma} allowed ranges provided by recent global analysis of neutrino data oscillation. From {delta}m{sub sol}{sup 2} bounds, neutrino masses are predicted in the range of values m{sub 1}{approx_equal}(1.706-2.494)x10{sup -3} eV, m{sub 2}{approx_equal}(6.675-12.56)x10{sup -3} eV, and m{sub 3}{approx_equal}(1.215-2.188)x10{sup -2} eV, respectively. The above allowed lepton mixing leads to the quark-lepton complementary relations {theta}{sub 12}{sup CKM}+{theta}{sub 12}{sup PMNS}{approx_equal}41.543 deg. -44.066 deg. and {theta}{sub 23}{sup CKM}+{theta}{sub 23}{sup PMNS}{approx_equal}36.835 deg. -38.295 deg. The new exotic scalar particles induce flavor changing neutral currents and contribute to lepton flavor violating processes such as E{yields}e{sub 1}e{sub 2}e{sub 3}, to radiative rare decays, {tau}{yields}{mu}{gamma}, {tau}{yields}e{gamma}, {mu}{yields}e{gamma}, as well as to the anomalous magnetic moments of fermions. I give general analytical expressions for the branching ratios of these rare decays and for the anomalous magnetic moments for charged leptons.
INTRODUCTION TO THREE-NEUTRINO MIXING PARAMETERS LISTINGS
.79 of the review "Neutrino Mass, Mixing and Oscillations" by K. Nakamura and S.T. Petcov.) Whether appear in the listings. The familiar two neutrino form for oscillations is P(a b) = sin2 (2) sin2 (m2 L 1 INTRODUCTION TO THREE-NEUTRINO MIXING PARAMETERS LISTINGS Updated April 2012 by M. Goodman
Leptonic mixing, family symmetries, and neutrino phenomenology
Medeiros Varzielas, I. de [Departamento de Fisica and Centro de Fisica Teorica de Particulas, Instituto Superior Tecnico, Avenida Rovisco Pais, 1049-001 Lisboa (Portugal); Fakultaet fuer Physik, Technische Universitaet Dortmund D-44221 Dortmund (Germany); Gonzalez Felipe, R. [Departamento de Fisica and Centro de Fisica Teorica de Particulas, Instituto Superior Tecnico, Avenida Rovisco Pais, 1049-001 Lisboa (Portugal); Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emidio Navarro, 1959-007 Lisboa (Portugal); Serodio, H. [Departamento de Fisica and Centro de Fisica Teorica de Particulas, Instituto Superior Tecnico, Avenida Rovisco Pais, 1049-001 Lisboa (Portugal)
2011-02-01T23:59:59.000Z
Tribimaximal leptonic mixing is a mass-independent mixing scheme consistent with the present solar and atmospheric neutrino data. By conveniently decomposing the effective neutrino mass matrix associated to it, we derive generic predictions in terms of the parameters governing the neutrino masses. We extend this phenomenological analysis to other mass-independent mixing schemes which are related to the tribimaximal form by a unitary transformation. We classify models that produce tribimaximal leptonic mixing through the group structure of their family symmetries in order to point out that there is often a direct connection between the group structure and the phenomenological analysis. The type of seesaw mechanism responsible for neutrino masses plays a role here, as it restricts the choices of family representations and affects the viability of leptogenesis. We also present a recipe to generalize a given tribimaximal model to an associated model with a different mass-independent mixing scheme, which preserves the connection between the group structure and phenomenology as in the original model. This procedure is explicitly illustrated by constructing toy models with the transpose tribimaximal, bimaximal, golden ratio, and hexagonal leptonic mixing patterns.
Absolute neutrino mass measurements
Wolf, Joachim [Karlsruhe Institute of Technology (KIT), IEKP, Postfach 3640, 76021 Karlsruhe (Germany)
2011-10-06T23:59:59.000Z
The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.
Quasi-Degenerate Neutrino Masses with Normal and Inverted Hierarchy
Francis, Ng K
2012-01-01T23:59:59.000Z
The effects of CP-phases on the three absolute quasi-degenerate Majorana neutrino (QDN) masses are stud-ied with neutrino mass matrices obeying {\\mu} - {\\tau} symmetry for normal as well as inverted hierarchical mass patterns. We have made further investigations on 1) the prediction of solar mixing angle which lies below tri-bimaximal mixing value in consistent with neutrino oscillation observational data, 2) the prediction on absolute neutrino mass parameter (mee) in 0{\
Yue-Liang Wu
2012-07-12T23:59:59.000Z
A model for the lepton-flavor mixing and CP violation is proposed based on the SU$_F$(3) gauge family symmetry and the Majorana feature of neutrinos. A consistent prediction for the lepton-flavor mixing and masses is shown to be resulted from the appropriate vacuum structure of SU$_F$(3) gauge symmetry breaking. By choosing the SU$_F$(3) gauge fixing condition to possess a residual $Z_2$ symmetry and requiring the vacuum structure of spontaneous symmetry breaking to have approximate global U(1) family symmetries, we obtain naturally the tri-bimaximal mixing matrix and largely degenerate neutrino masses in the neutrino sector and the small mixing matrix in the charged-lepton sector. With a simple ansatz that all the smallness due to the approximate global U(1) family symmetries is characterized by a single Wolfenstein parameter $\\lambda \\simeq 0.22$, and the charged-lepton mixing matrix has a similar hierarchy structure as the CKM quark mixing matrix, we arrive at a consistent prediction for the MNSP lepton-flavor mixing with a maximal spontaneous CP violation: $\\delta =\\pi/2$, $\\sin^2\\theta_{13} \\simeq 1/2\\lambda^2 \\simeq 0.024$ ($\\sin^22\\theta_{13} \\simeq 0.094$), $\\sin^2\\theta_{12} \\simeq 1/3{3}(1 - 2\\lambda^3) \\simeq 0.326$ and $\\sin^2\\theta_{23} \\simeq 1/2(1 - \\lambda^2) \\simeq 0.48$, which agree well with the current experimental data. The CP-violating Jarlskog-invariant is obtained to be $J_{CP} \\simeq 1/6\\lambda(1-\\lambda^2/2-\\lambda^3)\\sin\\delta \\simeq 0.035$, which is detectable in next generation neutrino experiment. The largely degenerate neutrino masses with the normal hierarchy and inverse hierarchy are discussed and found be at the order $m_{\
Neutrino mixing and dark energy
Blasone, M.; Capolupo, A.; Vitiello, G. [Dipartimento di Fisica 'E.R. Caianiello', I-84100 Salerno (Italy); INFN, Universita di Salerno, I-84100 Salerno (Italy); Capozziello, S. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Compl. Univ. Monte S. Angelo, Ed.N, Via Cinthia, I-80126 Naples (Italy); INFN Sez. di Napoli, Compl. Univ. Monte S. Angelo, Ed.N, Via Cinthia, I-80126 Naples (Italy)
2006-06-19T23:59:59.000Z
We report on the recent result that the non-perturbative vacuum structure associated with neutrino mixing leads to a non-zero contribution to the value of the dark energy.
Evidence for neutrino mass: A decade of discovery
Heeger, Karsten M.
2004-12-08T23:59:59.000Z
Neutrino mass and mixing are amongst the major discoveries of recent years. From the observation of flavor change in solar and atmospheric neutrino experiments to the measurements of neutrino mixing with terrestrial neutrinos, recent experiments have provided consistent and compelling evidence for the mixing of massive neutrinos. The discoveries at Super-Kamiokande, SNO, and KamLAND have solved the long-standing solar neutrino problem and demand that we make the first significant revision of the Standard Model in decades. Searches for neutrinoless double-beta decay probe the particle nature of neutrinos and continue to place limits on the effective mass of the neutrino. Possible signs of neutrinoless double-beta decay will stimulate neutrino mass searches in the next decade and beyond. I review the recent discoveries in neutrino physics and the current evidence for massive neutrinos.
Can Neutrinos be Degenerate in Mass?
John Ellis; Smaragda Lola
1999-04-13T23:59:59.000Z
We reconsider the possibility that the masses of the three light neutrinos of the Standard Model might be almost degenerate and close to the present upper limits from Tritium beta decay and cosmology. In such a scenario, the cancellations required by the latest upper limit on neutrinoless double-beta decay enforce near-maximal mixing that may be compatible only with the vacuum-oscillation scenario for solar neutrinos. We argue that the mixing angles yielded by degenerate neutrino mass-matrix textures are not in general stable under small perturbations. We evaluate within the MSSM the generation-dependent one-loop renormalization of neutrino mass-matrix textures that yielded degenerate masses and large mixing at the tree level. We find that m_{nu_e} > m_{nu_mu} > m_{nu_tau} after renormalization, excluding MSW effects on solar neutrinos. We verify that bimaximal mixing is not stable, and show that the renormalized masses and mixing angles are not compatible with all the experimental constraints, even for tanbeta as low as unity. These results hold whether the neutrino masses are generated by a see-saw mechanism with heavy neutrinos weighing approx. 10^{13} GeV or by non-renormalizable interactions at a scale approx. 10^5 GeV. We also comment on the corresponding renormalization effects in the minimal Standard Model, in which m_{nu_e} < m_{nu_mu} < m_{nu_tau}. Although a solar MSW effect is now possible, the perturbed neutrino masses and mixings are still not compatible with atmospheric- and solar-neutrino data.
Aaron Pierce; Hitoshi Murayama
2003-10-28T23:59:59.000Z
Recent data from from the Wilkinson Microwave Anisotropy Probe (WMAP) place important bounds on the neutrino sector. The precise determination of the baryon number in the universe puts a strong constraint on the number of relativistic species during Big-Bang Nucleosynthesis. WMAP data, when combined with the 2dF Galaxy Redshift Survey (2dFGRS), also directly constrain the absolute mass scale of neutrinos. These results impinge upon a neutrino oscillation interpretation of the result from the Liquid Scintillator Neutrino Detector (LSND). We also note that the Heidelberg--Moscow evidence for neutrinoless double beta decay is only consistent with the WMAP+2dFGRS data for the largest values of the nuclear matrix element.
Neutrino masses and solar neutrinos
Wolfenstein, L.
1992-01-01T23:59:59.000Z
It has been pointed out by Bahcall and Bethe and others that all solar neutrino data can be explained by MSW oscillations with m([nu][sub [mu
Determining the neutrino mass hierarchy
Parke, Stephen J.; /Fermilab
2006-07-01T23:59:59.000Z
In this proceedings I review the physics that future experiments will use to determine the neutrino mass hierarchy.
Flavor Mixing and CP Violation of Massive Neutrinos
Zhi-zhong Xing
2004-11-26T23:59:59.000Z
We present an overview of recent progress in the phenomenological study of neutrino masses, lepton flavor mixing and CP violation. We concentrate on the model-independent properties of massive neutrinos, both in vacuum and in matter. Current experimental constraints on the neutrino mass spectrum and the lepton flavor mixing parameters are summarized. The Dirac- and Majorana-like phases of CP violation, which are associated respectively with the long-baseline neutrino oscillations and the neutrinoless double beta decay, are discussed in detail. The seesaw mechanism, the leptogenesis scenario and the strategies to construct lepton mass matrices are briefly described. The features of flavor mixing between one sterile neutrino and three active neutrinos are also explored.
Neutrino masses and solar neutrinos
Wolfenstein, L.
1992-11-01T23:59:59.000Z
It has been pointed out by Bahcall and Bethe and others that all solar neutrino data can be explained by MSW oscillations with m({nu}{sub {mu}}) {approximately} 10{sup {minus}3} eV consistent with ideas grand unified theories (GUTS). There is a second possibility consistent with GUTS ideas with m({nu}{sub {tau}}) {approximately} 10{sup {minus}2} eV and m({nu} {sub {mu}}) {approximately} 10 {sup {minus}4} eV. The two cases can be distinguished by a measurement of the solar neutrinos from {sup {tau}}Be.
Mass Hierarchy via Mossbauer and Reactor Neutrinos
Stephen Parke; Hisakazu Minakata; Hiroshi Nunokawa; Renata Zukanovich Funchal
2008-12-10T23:59:59.000Z
We show how one could determine the neutrino mass hierarchy with Mossbauer neutrinos and also revisit the question of whether the hierarchy can be determined with reactor neutrinos.
Mass Hierarchy via Mossbauer and Reactor Neutrinos
Parke, Stephen; Nunokawa, Hiroshi; Funchal, Renata Zukanovich
2008-01-01T23:59:59.000Z
We show how one could determine the neutrino mass hierarchy with Mossbauer neutrinos and also revisit the question of whether the hierarchy can be determined with reactor neutrinos.
INTRODUCTION TO THREE-NEUTRINO MIXING PARAMETERS LISTINGS
.77 of the review "Neutrino Mass, Mixing and Oscillations" by K. Nakamura and S.T. Petcov.) Whether appear in the listings. The familiar two neutrino form for oscillations is P(a b) = sin2 (2) sin2 (m2 L scale, the equation for neutrino oscillation in vacuum is: P( e) = P1 + P2 + P3 + P4 P1 = sin2 (23) sin
Pattern of neutrino mixing in grand unified theories
Milton, K.; Tanaka, K.
1981-01-01T23:59:59.000Z
It was found previously in SO(10) grand unified theories that if the neutrinos have a Dirac mass and a right-handed Majorana mass (approx. 10/sup 15/GeV) but no left-handed Majorana mass, there is small ..nu../sub e/ mixing but ..nu../sub ..mu../ - ..nu../sub tau/ mixing can be substantial. This problem is reexamined on the basis of a formalism that assumes that the up, down, lepton, and neutrino mass matrices arise from a single complex 10 and a single 126 Higgs boson. This formalism determines the Majorana mass matrix in terms of quark mass matrices. Adopting three different sets of quark mass matrices that produce acceptable fermion mass ratios and Cabbibo mixing produces results consistent with the above; however, in the optimum case, ..nu../sub e/ - ..nu../sub ..mu../ mixing can be of the order of the Cabbibo angle.
Gauge Trimming of Neutrino Masses
Chen, Mu-Chun; /Fermilab /UC, Irvine; de Gouvea, Andre; /Northwestern U. /Fermilab; Dobrescu, Bogdan A.; /Fermilab
2006-12-01T23:59:59.000Z
We show that under a new U(1) gauge symmetry, which is non-anomalous in the presence of one ''right-handed neutrino'' per generation and consistent with the standard model Yukawa couplings, the most general fermion charges are determined in terms of four rational parameters. This generalization of the B-L symmetry with generation-dependent lepton charges leads to neutrino masses induced by operators of high dimensionality. Neutrino masses are thus naturally small without invoking physics at energies above the TeV scale, whether neutrinos are Majorana or Dirac fermions. This ''Leptocratic'' Model predicts the existence of light quasi-sterile neutrinos with consequences for cosmology, and implies that collider experiments may reveal the origin of neutrino masses.
David O. Caldwell
1998-12-01T23:59:59.000Z
Despite direct observations favoring a low mass density, a critical density universe with a neutrino component of dark matter provides the best existing model to explain the observed structure of the universe over more than three orders of magnitude in distance scale. In principle this hot dark matter could consist of one, two, or three species of active neutrinos. If all present indications for neutrino mass are correct, however, only the two-species (muon neutrino and tau neutrino) possibility works. This requires the existence of at least one light sterile neutrino to explain the solar electron neutrino deficit via nu(e)->nu(s), leaving nu(mu)->nu(tau) as the explanation for the anomalous nu(mu)/nu(e) ratio produced by atmospheric neutrinos, and having the LSND experiment demonstrating via anti-nu(mu)-> anti-nu(e) the mass difference between the light nu(e)-nu(s) pair and the heavier nu(mu)-nu(tau) pair required for dark matter. Other experiments do not conflict with the LSND results when all the experiments are analyzed in the same way, and when analyzed conservatively the LSND data is quite compatible with the mass difference needed for dark matter. Further support for this mass pattern is provided by the need for a sterile neutrino to rescue heavy-element nucleosynthesis in supernovae, and it could even aid the concordance in light element abundances from the early universe.
SOME ASPECTS OF NEUTRINO MIXING AND OSCILLATIONS
Shyamasundar, R.K.
SOME ASPECTS OF NEUTRINO MIXING AND OSCILLATIONS THESIS SUBMITTED TO THE UNIVERSITY OF CALCUTTA into the fascinating world of neutrinos and for being an excellent teacher and a perfect guide. I convey my regards everything I know about neutrino phenomenology, I owe to him. I consider myself very fortunate to have him
Constraints on the Sum of Neutrino Masses from Cosmology and their impact on world neutrino data
A. Melchiorri; G. L. Fogli; E. Lisi; A. Marrone; A. Palazzo; P. Serra; J. I. Silk
2005-01-25T23:59:59.000Z
We derive upper limits on the sum of neutrino masses from an updated combination of data from Cosmic Microwave Background experiments and Galaxy Redshifts Surveys. The results are discussed in the context of three-flavor neutrino mixing and compared with neutrino oscillation data, with upper limits on the effective neutrino mass in Tritium beta decay from the Mainz and Troitsk experiments and with the claimed lower bound on the effective Majorana neutrino mass in neutrinoless double beta decay from the Heidelberg-Moscow experiment.
Absolute Values of Neutrino Masses: Status and Prospects
S. M. Bilenky; C. Giunti; J. A. Grifols; E. Masso
2003-03-27T23:59:59.000Z
Compelling evidences in favor of neutrino masses and mixing obtained in the last years in Super-Kamiokande, SNO, KamLAND and other neutrino experiments made the physics of massive and mixed neutrinos a frontier field of research in particle physics and astrophysics. There are many open problems in this new field. In this review we consider the problem of the absolute values of neutrino masses, which apparently is the most difficult one from the experimental point of view. We discuss the present limits and the future prospects of beta-decay neutrino mass measurements and neutrinoless double-beta decay. We consider the important problem of the calculation of nuclear matrix elements of neutrinoless double-beta decay and discuss the possibility to check the results of different model calculations of the nuclear matrix elements through their comparison with the experimental data. We discuss the upper bound of the total mass of neutrinos that was obtained recently from the data of the 2dF Galaxy Redshift Survey and other cosmological data and we discuss future prospects of the cosmological measurements of the total mass of neutrinos. We discuss also the possibility to obtain information on neutrino masses from the observation of the ultra high-energy cosmic rays (beyond the GZK cutoff). Finally, we review the main aspects of the physics of core-collapse supernovae, the limits on the absolute values of neutrino masses from the observation of SN1987A neutrinos and the future prospects of supernova neutrino detection.
Effect of non-standard interaction for radiative neutrino mass model
Konishi, Y.; Sato, J.; Shimomura, T. [Department of Physics, Saitama University, Shimo-okubo, Sakura-ku, Saitama, 338-8570 (Japan); Department of Physics, Niigata University, Niigata, 950-2181 (Japan)
2012-07-27T23:59:59.000Z
We examined effects of non-standard interactions (NSIs) in a radiative neutrino mass model. The radiative neutrino mass model suggested by Kraus Nasri and Trodden can explain not only neutrino flavor mixing and neutrino masses, but also dark matter relic abundance. Although the NSI effects of the model are too small to be detected by present neutrino oscillation experiments, we might observe the small effects in future experiments such as neutrino factory.
Neutrino mixing and oscillations in astrophysical environments
Balantekin, A. B. [Physics Department, University of Wisconsin, Madison WI 53706 (United States)
2014-05-02T23:59:59.000Z
A brief review of the current status of neutrino mixing and oscillations in astrophysical environments, with particular emphasis on the Sun and core-collapse supernovae, is given. Implications of the existence of sterile states which mix with the active neutrinos are discussed.
Neutrino Mixing and Oscillations in Astrophysical Environments
A. B. Balantekin
2014-01-22T23:59:59.000Z
A brief review of the current status of neutrino mixing and oscillations in astrophysical environments, with particular emphasis on the Sun and core-collapse supernovae, is given. Implications of the existence of sterile states which mix with the active neutrinos are discussed.
Transformative A_4 Mixing of Neutrinos with CP Violation
Ernest Ma
2015-08-25T23:59:59.000Z
A new theoretical insight into the pattern of neutrino mixing and leptonic $CP$ violation is presented. It leads naturally and uniquely to a specific dark sector of three real neutral scalar singlets, with the radiative implementation of the inverse seesaw mechanism for neutrino mass. The new simple but crucial enabling idea is that a familiar $A_4$ transformation turns any orthogonal $3 \\times 3$ matrix into one which predicts $\\theta_{23} = \\pi/4$ and $\\delta_{CP} = \\pm \\pi/2$ for the neutrino mixing matrix, in good agreement with present data.
What we (would like to) know about the neutrino mass
G. L. Fogli; E. Lisi; A. Marrone; A. Palazzo; A. M. Rotunno
2008-09-17T23:59:59.000Z
We present updated values for the mass-mixing parameters relevant to neutrino oscillations, with particular attention to emerging hints in favor of theta_13>0. We also discuss the status of absolute neutrino mass observables, and a possible approach to constrain theoretical uncertainties in neutrinoless double beta decay. Desiderata for all these issues are also briefly mentioned.
Textures for neutrino mass matrices
Leontaris, G.K.; Lola, S.; Scheich, C.; Vergados, J.D. [Theoretical Physics Division, Ioannina University, GR-45110 Ioannina (Greece)] [Theoretical Physics Division, Ioannina University, GR-45110 Ioannina (Greece); [Institut fuer Theoretische Physik, Univerisitaet Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); [Departamento de Fisica Teorica, Universidad Autonoma de Madrid, 28049, Madrid (Spain); [Department of Natural Sciences, University of Cyprus, Nicosia (Cyprus)
1996-06-01T23:59:59.000Z
We give a classification of heavy Majorana neutrino mass matrices with up to three texture zeros, assuming the Dirac masses of the neutrinos to be of the same form as the ones of the up quarks in the five texture zero solutions for the quark matrices. This is the case for many unified and partially unified models. We find that it is possible to have solutions which account for the solar and atmospheric neutrino problems as well as the COBE observations simultaneously, and we motivate the existence of such solutions from symmetries. {copyright} {ital 1996 The American Physical Society.}
Possible deviation from the tri-bimaximal neutrino mixing in a seesaw model
Kang, Sin Kyu; Xing Zhizhong; Zhou Shun [School of Physics, Seoul National University, Seoul 151-734 (Korea, Republic of); CCAST (World Laboratory), P.O. Box 8730, Beijing 100080 (China) and Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918, Beijing 100049 (China)
2006-01-01T23:59:59.000Z
We propose a simple but suggestive seesaw model with two phenomenological conjectures: three heavy (right-handed) Majorana neutrinos are degenerate in mass in the symmetry limit and three light Majorana neutrinos have the tri-bimaximal mixing pattern V{sub 0}. We show that a small mass splitting between the first generation and the other two generations of heavy Majorana neutrinos is responsible for the deviation of the solar neutrino mixing angle {theta}{sub 12} from its initial value 35.3 deg. given by V{sub 0}, and the slight breaking of the mass degeneracy between the second and third generations of heavy Majorana neutrinos results in a small mixing angle {theta}{sub 13} and a tiny departure of the atmospheric neutrino mixing angle {theta}{sub 23} from 45 deg. It turns out that a normal hierarchy of the light neutrino mass spectrum is favored in this seesaw scenario.
Absolute Values of Neutrino Masses implied by the Seesaw Mechanism
Tsujimoto, H
2005-01-01T23:59:59.000Z
It is found that the seesaw mechanism not only explain the smallness of neutrino masses but also account for the large mixing angles simultaneously, once the unification of the neutrino Dirac mass matrix with that of up-quark sector is realized. We show that provided the Majorana masses have hierarchical structure as is seen in the up-quark sector, we can reduce the information about the absolute values of neutrino masses through the data set of neutrino experiments. The results for the light neutrino masses are $m_1:m_2:m_3\\approx 1:3:17$ $(m_1\\simeq m_2:m_3\\approx 1.2:1)$ in the case of normal mass spectrum (inverted mass spectrum), and the heaviest Majorana mass turns out to be $m_3^R=1\\times 10^{15}$ GeV which just corresponds to the GUT scale.
Mixed MSW and Vacuum Solutions of Solar Neutrino Problem
Qiu-Yu Liu
1997-08-11T23:59:59.000Z
Assuming three flavour neutrino mixing takes place in vacuum, we investigate the possibility that the solar $\
Mixed MSW and Vacuum Solutions of Solar Neutrino Problem
Liu, Q Y
1997-01-01T23:59:59.000Z
Assuming three flavour neutrino mixing takes place in vacuum, we investigate the possibility that the solar $\
Neutrino mass and oscillation as probes of physics beyond the Standard Model
Khalil, S
2000-01-01T23:59:59.000Z
We present a review of the present status of the problem of neutrino masses and mixing including a survey of theoretical motivations and models, experimental searches and implications of recently appeared solar and atmospheric neutrino data, which strongly indicate nonzero neutrino masses and mixing angles.
Flavor structure in D-brane models: Majorana neutrino masses
Yuta Hamada; Tatsuo Kobayashi; Shohei Uemura
2014-06-11T23:59:59.000Z
We study the flavor structure in intersecting D-brane models. We study anomalies of the discrete flavor symmetries. We analyze the Majorana neutrino masses, which can be generated by D-brane instanton effects. It is found that a certain pattern of mass matrix is obtained and the cyclic permutation symmetry remains unbroken. As a result, trimaximal mixing matrix can be realized if Dirac neutrino mass and charged lepton mass matrices are diagonal.
Limits on Sterile Neutrino Mixing using Atmospheric Neutrinos in Super-Kamiokande
:,; Haga, Y; Hayato, Y; Ikeda, M; Iyogi, K; Kameda, J; Kishimoto, Y; Miura, M; Moriyama, S; Nakahata, M; Nakano, Y; Nakayama, S; Sekiya, H; Shiozawa, M; Suzuki, Y; Takeda, A; Tanaka, H; Tomura, T; Ueno, K; Wendell, R A; Yokozawa, T; Irvine, T; Kajita, T; Kametani, I; Kaneyuki, K; Lee, K P; McLachlan, T; Nishimura, Y; Richard, E; Okumura, K; Labarga, L; Fernandez, P; Berkman, S; Tanaka, H A; Tobayama, S; Gustafson, J; Kearns, E; Raaf, J L; Stone, J L; Sulak, L R; Goldhaber, M; Carminati, G; Kropp, W R; Mine, S; Weatherly, P; Renshaw, A; Smy, M B; Sobel, H W; Takhistov, V; Ganezer, K S; Hartfiel, B L; Hill, J; Keig, W E; Hong, N; Kim, J Y; Lim, I T; Akiri, T; Himmel, A; Scholberg, K; Walter, C W; Wongjirad, T; Ishizuka, T; Tasaka, S; Jang, J S; Learned, J G; Matsuno, S; Smith, S N; Hasegawa, T; Ishida, T; Ishii, T; Kobayashi, T; Nakadaira, T; Nakamura, K; Oyama, Y; Sakashita, K; Sekiguchi, T; Tsukamoto, T; Suzuki, A T; Takeuchi, Y; Bronner, C; Hirota, S; Huang, K; Ieki, K; Kikawa, T; Minamino, A; Murakami, A; Nakaya, T; Suzuki, K; Takahashi, S; Tateishi, K; Fukuda, Y; Choi, K; Itow, Y; Mitsuka, G; Mijakowski, P; Hignight, J; Imber, J; Jung, C K; Yanagisawa, C; Ishino, H; Kibayashi, A; Koshio, Y; Mori, T; Sakuda, M; Yamaguchi, R; Yano, T; Kuno, Y; Tacik, R; Kim, S B; Okazawa, H; Choi, Y; Nishijima, K; Koshiba, M; Suda, Y; Totsuka, Y; Yokoyama, M; Martens, K; Marti, Ll; Vagins, M R; Martin, J F; de Perio, P; Konaka, A; Wilking, M J; Chen, S; Zhang, Y; Connolly, K; Wilkes, R J
2014-01-01T23:59:59.000Z
We present limits on sterile neutrino mixing using 4,438 live-days of atmospheric neutrino data from the Super-Kamiokande experiment. We search for fast oscillations driven by an eV$^2$-scale mass splitting and for oscillations into sterile neutrinos instead of tau neutrinos at the atmospheric mass splitting. When performing both these searches we assume that the sterile mass splitting is large, allowing $\\sin^2(\\Delta m^2 L/4E)$ to be approximated as $0.5$, and we assume that there is no mixing between electron neutrinos and sterile neutrinos ($|U_{e4}|^2 = 0$). No evidence of sterile oscillations is seen and we limit $|U_{\\mu4}|^2$ to less than 0.041 and $|U_{\\tau4}|^2$ to less than 0.18 for $\\Delta m^2 > 0.8$ eV$^2$ at the 90% C.L. in a 3+1 framework. The approximations that can be made with atmospheric neutrinos allow these limits to be easily applied to 3+N models, and we provide our results in a generic format to allow comparisons with other sterile neutrino models.
Cosmological neutrino mass detection: The Best probe of neutrino lifetime
Serpico, Pasquale D.; /Fermilab
2007-01-01T23:59:59.000Z
Future cosmological data may be sensitive to the effects of a finite sum of neutrino masses even as small as {approx}0.06 eV, the lower limit guaranteed by neutrino oscillation experiments. We show that a cosmological detection of neutrino mass at that level would improve by many orders of magnitude the existing limits on neutrino lifetime, and as a consequence on neutrino secret interactions with (quasi-)massless particles as in majoron models. On the other hand, neutrino decay may provide a way-out to explain a discrepancy {approx}< 0.1 eV between cosmic neutrino bounds and Lab data.
Cosmological Neutrino Mass Detection: The Best Probe of Neutrino Lifetime
Serpico, Pasquale D. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States)
2007-04-27T23:59:59.000Z
Future cosmological data may be sensitive to the effects of a finite sum of neutrino masses even as small as {approx}0.06 eV, the lower limit guaranteed by neutrino oscillation experiments. We show that a cosmological detection of neutrino mass at that level would improve by many orders of magnitude the existing limits on neutrino lifetime, and as a consequence, on neutrino secret interactions with (quasi)massless particles as in Majoron models. On the other hand, neutrino decay may provide a way out to explain a discrepancy < or approx. 0.1 eV between cosmic neutrino bounds and lab data.
Asan Damanik; Mirza Satriawan; Pramudita Anggraita; Arief Hermanto; Muslim
2007-12-13T23:59:59.000Z
We evaluate the predictive power of the neutrino mass matrices arising from seesaw mechanism with heavy Majorana mass matrices subject to texture zero and satisfy a cyclic permutation invariant form to the solar neutrino mixing phenomena. From eight possible patterns of heavy Majorana neutrino mass matrix, we found that there is no heavy Majorana neutrino mass matrix to be invariant in form under a cyclic permutation. But, by imposing an additional assumption that at least one of the 2x2 sub-matrices of heavy Majorana neutrino mass matrix inverse having zero determinant, we found that only two of the eight possible patterns for heavy Majorana neutrino mass matrices to be invariant under a cyclic permutation. One of the two invariant heavy Majorana neutrino mass matrices could produces neutrino mass matrix $M_{\
Neutrino Mass Models: Impact of non-zero reactor angle
Stephen F. King
2011-06-25T23:59:59.000Z
In this talk neutrino mass models are reviewed and the impact of a non-zero reactor angle and other deviations from tri-bimaximal mixing are discussed. We propose some benchmark models, where the only way to discriminate between them is by high precision neutrino oscillation experiments.
Corrections to tribimaximal neutrino mixing: Renormalization and Planck scale effects
Dighe, Amol [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Goswami, Srubabati [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India); Rodejohann, Werner [Max-Planck-Institut fuer Kernphysik, Postfach 103980, D-69029 Heidelberg (Germany)
2007-04-01T23:59:59.000Z
We study corrections to tribimaximal (TBM) neutrino mixing from renormalization group (RG) running and from Planck scale effects. We show that while the RG effects are negligible in the standard model (SM), for quasidegenerate neutrinos and large tan{beta} in the minimal supersymmetric standard model (MSSM) all three mixing angles may change significantly. In both these cases, the direction of the modification of {theta}{sub 12} is fixed, while that of {theta}{sub 23} is determined by the neutrino mass ordering. The Planck scale effects can also change {theta}{sub 12} up to a few degrees in either direction for quasidegenerate neutrinos. These effects may dominate over the RG effects in the SM, and in the MSSM with small tan{beta}. The usual constraints on neutrino masses, Majorana phases or tan{beta} stemming from RG running arguments can then be relaxed. We quantify the extent of Planck scale effects on the mixing angles in terms of 'mismatch phases' which break the symmetries leading to TBM. In particular, we show that when the mismatch phases vanish, the mixing angles are not affected in spite of the Planck scale contribution. Similar statements may be made for {mu}-{tau} symmetric mass matrices.
Small entries of neutrino mass matrices
E. Kh. Akhmedov
1999-09-15T23:59:59.000Z
We consider phenomenologically allowed structures of the neutrino mass matrix in the case of three light neutrino species. Constraints from the solar, atmospheric and reactor neutrino experiments as well as those from the neutrinoless double beta decay are taken into account. Both hierarchical and quasi-degenerate neutrino mass cases are studied. Assuming maximal $\
Status and implications of neutrino masses: a brief panorama
Valle, J W F
2015-01-01T23:59:59.000Z
With the historic discovery of the Higgs boson our picture of particle physics would have been complete were it not for the neutrino sector and cosmology. I briefly discuss the role of neutrino masses and mixing upon gauge coupling unification, electroweak breaking and the flavor sector. Time is ripe for new discoveries such as leptonic CP violation, charged lepton flavor violation and neutrinoless double beta decay. Neutrinos could also play a role in elucidating the nature of dark matter and cosmic inflation.
Constraints on the relic neutrino abundance and implications for cosmological neutrino mass limits
Bell, Nicole F.; /Fermilab
2004-01-01T23:59:59.000Z
The authors examine a mechanism which can lead to flavor transformation of neutrino-antineutrino asymmetries in the early universe, a process which is unavoidable when the neutrino mixing angles are large. This sets the best limit on the lepton number of the universe, and hence on the relic neutrino abundance. They also consider the consequences for the relic neutrino abundance if extra neutrino interactions are allowed, e.g., the coupling of the neutrinos to a light (compared to m{sub {nu}}) boson. For a wide range of couplings not excluded by other considerations, the relic neutrinos would annihilate to bosons at late times, and thus make a negligible contribution to the matter density today. This mechanism evades the neutrino mass limits arising from large scale structure.
Introduction to direct neutrino mass measurements and KATRIN
Thomas Thümmler; for the KATRIN Collaboration
2010-12-10T23:59:59.000Z
The properties of neutrinos and especially their rest mass play an important role at the intersections of cosmology, particle physics and astroparticle physics. At present there are two complementary approaches to address this topic in laboratory experiments. The search for neutrinoless double beta decay probes whether neutrinos are Majorana particles and determines an effective neutrino mass value. On the other hand experiments such as MARE, KATRIN and the recently proposed Project 8 will investigate the spectral shape of beta-decay electrons close to their kinematic endpoint in order to determine the neutrino rest mass with a model-independent method. Here, because of neutrino flavour mixing, the neutrino mass appears as an average of all neutrino mass eigenstates contributing to the electron neutrino. The KArlsruhe TRItium Neutrino experiment (KATRIN) is currently the experiment in the most advanced status of commissioning. It combines an ultra-luminous molecular windowless gaseous tritium source with an integrating high-resolution spectrometer of MAC-E filter type. It will investigate the neutrino rest mass with 0.2 eV/c (90% C.L.) sensitivity and allow beta spectroscopy close to the tritium endpoint at 18.6 keV with unprecedented precision.
Supernova II Neutrino Bursts and Neutrino Massive Mixing
David B. Cline
2001-03-08T23:59:59.000Z
We describe the Neutrino Spectrum and detection for SN II sources. We discuss the effects of neutrino mixing in the SN II. A new analysis of SN1987A is described. We discuss the possible detection of the diffuse relic SN II flux. Finally we discuss a new detection concept, OMNIS, for Nu sub mu and Nu sub tau and detection and compare with other present and future SN detectors.
Xiangdong Shi; George M. Fuller
1998-12-17T23:59:59.000Z
In the paper "Big Bang Nucleosynthesis and Active-Sterile Neutrino Mixing: Evidence for Maximal Muon-Neutrino/Sterile-Neutrino Mixing in Super Kamiokande" (astro-ph/9810075), we suggested that to evade the Big Bang Nucleosynthesis exclusion of the muon neutrino to sterile neutrino oscillation explanation of the Super Kamiokande data, the tau neutrino must have a mass over about 15 eV and it must mix with a lighter sterile neutrino. A stable tau neutrino with this mass is inconsistent with cosmological structure formation. In a comment on our paper (astro-ph/9811067), Foot and Volkas argued that our result is incorrect and that the required tau neutrino mass should be much lower. Here we back up our original result with a more detailed calculation. We show that the argument of Foot and Volkas is invalid, most likely due to an insufficient energy resolution in the low energy part of the neutrino spectrum.
Maximal CP Violation in Flavor Neutrino Masses
Kitabayashi, Teruyuki
2015-01-01T23:59:59.000Z
Since flavor neutrino masses $M_{\\mu\\mu,\\tau\\tau,\\mu\\tau}$ can be expressed in terms of $M_{ee,e\\mu,e\\tau}$, mutual dependence among $M_{\\mu\\mu,\\tau\\tau,\\mu\\tau}$ is derived by imposing some constraints on $M_{ee,e\\mu,e\\tau}$. For appropriately imposed constraints on $M_{ee,e\\mu,e\\tau}$, we show a texture of neutrino mass matrix giving rise to maximal CP violation. When the atmospheric neutrino mixing is also maximal, we discuss various specific textures of neutrino mass matrices including the texture with $M_{\\tau\\tau}=M^\\ast_{\\mu\\mu}$ derived as the simplest solution to the constraint of $M_{\\tau\\tau}-M_{\\mu\\mu}$=imaginary, which is required by the constraint of $M_{e\\mu}\\cos\\theta_{23}-M_{e\\tau}\\sin\\theta_{23}$=real for $\\cos 2\\theta_{23}=0$. It is found that Majorana CP violation depends on the phase of $M_{ee}$.
Vanishing effective mass of the neutrinoless double beta decay including light sterile neutrinos
Y. F. Li; Si-shuo Liu
2011-11-28T23:59:59.000Z
Light sterile neutrinos with masses at the sub-eV or eV scale are hinted by current experimental and cosmological data. Assuming the Majorana nature of these hypothetical particles, we discuss their effects in the neutrinoless double beta decay by exploring the implications of a vanishing effective Majorana neutrino mass. Allowed ranges of neutrino masses, mixing angles and Majorana CP-violating phases are illustrated in some instructive cases for both normal and inverted mass hierarchies of three active neutrinos.
Neutrino masses and Neutrinoless Double Beta Decay: Status and expectations
Oliviero Cremonesi
2010-02-07T23:59:59.000Z
Two most outstanding questions are puzzling the world of neutrino Physics: the possible Majorana nature of neutrinos and their absolute mass scale. Direct neutrino mass measurements and neutrinoless double beta decay (0nuDBD) are the present strategy to solve the puzzle. Neutrinoless double beta decay violates lepton number by two units and can occurr only if neutrinos are massive Majorana particles. A positive observation would therefore necessarily imply a new regime of physics beyond the standard model, providing fundamental information on the nature of the neutrinos and on their absolute mass scale. After the observation of neutrino oscillations and given the present knowledge of neutrino masses and mixing parameters, a possibility to observe 0nuDBDD at a neutrino mass scale in the range 10-50 meV could actually exist. This is a real challenge faced by a number of new proposed projects. Present status and future perpectives of neutrinoless double-beta decay experimental searches is reviewed. The most important parameters contributing to the experimental sensitivity are outlined. A short discussion on nuclear matrix element calculations is also given. Complementary measurements to assess the absolute neutrino mass scale (cosmology and single beta decays) are also discussed.
Overview of Neutrino Mixing Models and Their Mixing Angle Predictions
Albright, Carl H.
2009-11-01T23:59:59.000Z
An overview of neutrino-mixing models is presented with emphasis on the types of horizontal flavor and vertical family symmetries that have been invoked. Distributions for the mixing angles of many models are displayed. Ways to differentiate among the models and to narrow the list of viable models are discussed.
Neutrino mass matrices with a democratic texture
Kleppe, A. [Dep. of Mathematical Physics, LTH, Box 118, 22100 Lund (Sweden)
1997-06-15T23:59:59.000Z
The structure of the neutrino mass matrices is investigated, in a scheme where the minimal three-family Standard Model is extended by including right-handed neutrinos. No assumption is made about the presence of a large mass scale, like in the see-saw scheme. Certain peculiar features of the usual democratic mass matrix are investigated, and used to define matrices with a 'democratic texture'. By demanding that the neutrino mass matrices have a specific form with such a democratic texture, Majorana mass spectra with three massless (light) neutrinos and either two or three massive neutrinos, are obtained.
Measuring the Neutrino Mass Hierarchy with Atmospheric Neutrinos
D. F. Cowen; T. DeYoung; D. Grant; D. A. Dwyer; S. R. Klein; K. B. Luk; D. R. Williams; for the IceCube/PINGU Collaboration
2014-09-24T23:59:59.000Z
The proposed PINGU experiment to measure the neutrino mass hierarchy is presented, in the context of long-range planning by the U.S. nuclear physics community.
Absolute Values of Neutrino Masses implied by the Seesaw Mechanism
H. Tsujimoto
2005-12-12T23:59:59.000Z
It is found that the seesaw mechanism not only explain the smallness of neutrino masses but also account for the large mixing angles simultaneously, even if the unification of the neutrino Dirac mass matrix with that of up-type quark sector is realized. We show that provided the Majorana masses have hierarchical structure as is seen in the up-type quark sector and all mass matrices are real, we can reduce the information about the absolute values of neutrino masses through the data set of neutrino experiments. Especially for $\\theta_{13}=0$, we found that the neutrino masses are decided as $m_1:m_2:m_3\\approx 1:3:17$ or $1:50:250$ ($m_1\\simeq m_2:m_3\\approx 3:1$ or $12:1$) in the case of normal mass spectrum (inverted mass spectrum), and the greatest Majorana mass turns out to be $m_3^R=1\\times 10^{15}$ GeV which just corresponds to the GUT scale. Including the decoupling effects caused by three singlet neutrinos, we also perform a renormalization group analysis to fix the neutrino Yukawa coupling matrix at low energy.
Small Neutrino Masses from Supersymmetry Breaking
Arkani-Hamed, Nima
2009-01-01T23:59:59.000Z
neutrino mass matrices. The above Majorana and Dirac casesMajorana mass for N of the order F/M ? 100GeV, yielding a LR neutrino mass matrixMajorana masses M and couplings to the lepton doublets: L = M NN + ?LNH where M and ? are mass matrices.
Estimations of baryon asymmetry for different neutrino mass models
Amal Kr. Sarma; Hijam Zeen Devi; N. Nimai Singh
2006-04-05T23:59:59.000Z
We present a comparison of the numerical prediction on baryon asymmetry of the Universe in different neutrino mass models. We start with a very brief review on the main formalism of baryogenesis via leptogenesis through decay of heavy right-handed Majorana neutrinos, and then calculate the baryon asymmetry of the universe for known six neutrino mass models viz., three quasi-degenerate, two inverted and one normal hierarchical models, which are derived from canonical seesaw formula. The corresponding mass matrices for the right-handed Majorana neutrino as well as the Dirac neutrino, which are fixed at the seesaw stage for generating correct light neutrino mass matrices, are again employed in the calculation of baryogenesis. This procedure removes possible ambiguity on the choices of Dirac neutrino and right-handed Majorana mass matrices, and fixes input parameters at the seesaw stage. We find that the ranges of predictions from both normal hierarchical model and degenerate model (DegT1A) are almost consistent with the observed baryon asymmetry of the universe. Combining the present result with other predictions such as light neutrino masses and mixing angles, and stability under radiative corrections in MSSM, the normal hierarchical model appears to be the most favourable choice of nature.
Neutrino Mass Matrix in Triplet Higgs Models with A-bar 4 Symmetry
Baek, Seungwon [Institute of Basic Science and Department of Physics, Korea University, Seoul (Korea, Republic of); Chu Oh, Myoung [Department of Physics, University of Seoul, Seoul (Korea, Republic of)
2009-04-19T23:59:59.000Z
The tribimaximal form of the neutrino mixing matrix can be naturally obtained with A-bar 4 flavor symmetry. We consider triplet Higgs model with A-bar 4 symmetry to generate the neutrino masses. With neutrino oscillation data we show that the mass matrix can be (almost) reconstructed, which allows us to predict the absolute neutrino mass scale including the neutrinoless double beta decay, the decay rates of the doubly charged Higgs boson to lepton pairs.
Zhi-zhong Xing
2001-07-02T23:59:59.000Z
We point out two simple but instructive possibilities to construct the charged lepton and neutrino mass matrices, from which the nearly bi-maximal neutrino mixing with large T violation can naturally emerge. The two lepton mixing scenarios are compatible very well with current experimental data on solar and atmospheric neutrino oscillations, and one of them may lead to an observable T-violating asymmetry between \
Probing the absolute mass scale of neutrinos
Formaggio, Joseph A.
The Karlsruhe Tritium Neutrino (KATRIN) experiment is the next generation tritium beta decay experiment with sub-eV sensitivity to make a direct, model independent measurement of the neutrino mass. The principle of the ...
Solar mass-varying neutrino oscillations
V. Barger; Patrick Huber; Danny Marfatia
2005-09-30T23:59:59.000Z
We propose that the solar neutrino deficit may be due to oscillations of mass-varying neutrinos (MaVaNs). This scenario elucidates solar neutrino data beautifully while remaining comfortably compatible with atmospheric neutrino and K2K data and with reactor antineutrino data at short and long baselines (from CHOOZ and KamLAND). We find that the survival probability of solar MaVaNs is independent of how the suppression of neutrino mass caused by the acceleron-matter couplings varies with density. Measurements of MeV and lower energy solar neutrinos will provide a rigorous test of the idea.
Graphene, neutrino mass and oscillation
Z. Y. Wang
2011-03-28T23:59:59.000Z
A resolution of the Abraham-Minkowski dilemma is presented that other constant velocities can play the role of c in the theory of relativity. For example, in 2005 electrons of graphene were discovered to behave as if the coefficient is a Fermi velocity. Then we propose a conjecture for neutrinos to avoid the contradiction among two-component theory, negative rest mass-square and oscillation.
S. Pascoli; S. T. Petcov
2007-11-30T23:59:59.000Z
If future neutrino oscillation experiments show that the neutrino mass spectrum is with normal ordering, m1 | > 0.01 eV give negative results, the next frontier in the quest for neutrinoless double beta-decay will correspond to || ~ 0.001 eV. Assuming that massive neutrinos are Majorana particles and their exchange is the dominant mechanism generating neutrinoless double beta-decay, we analise the conditions under which ||, in the case of three neutrino mixing and neutrino mass spectrum with normal ordering, would satisfy || > 0.001 eV. We consider the specific cases of i) normal hierarchical neutrino mass spectrum, ii) of relatively small value of the CHOOZ angle theta13 as well as iii) the general case of spectrum with normal ordering, partial hierarchy and a value of theta13 close to the existing upper limit. We study the ranges of the lightest neutrino mass m1 and/or of sin^2 theta13, for which ||> 0.001 eV and discuss the phenomenological implications of such scenarios. We provide also an estimate of || when the three neutrino masses and the neutrino mixing originate from neutrino mass term of Majorana type for the (left-handed) flavour neutrinos and m1 Ue1^2 + m2 U_e2^2 + m3 Ue3^2 =0, but there does not exist a symmetry which forbids the neutrinoless double beta-decay.
CP-phase effects on the effective neutrino mass m{sub ee} in the case of quasidegenerate neutrinos
Maalampi, J. [Department of Physics, P.O. Box 35, FIN-40014 University of Jyvaeskylae (Finland); Helsinki Institute of Physics, P.O. Box 64, FIN-00014 University of Helsinki (Finland); Riittinen, J. [Department of Physics, P.O. Box 35, FIN-40014 University of Jyvaeskylae (Finland)
2010-02-01T23:59:59.000Z
We study the possibility that the three mass states of the ordinary active neutrinos actually split into pairs of quasidegenerate states, with {Delta}m{sub kk}{sup '2{approx}}10{sup -12} eV{sup 2} or less, as a result of mixing of active neutrinos with sterile neutrinos. While in laboratory experiments these quasidegenerate pairs will look identical to single active states, the CP phase factors associated with active-sterile mixing might cause cancellations in the effective electron neutrino mass m{sub ee} measured in the neutrinoless double beta decay experiments thereby revealing the split nature of states.
Neutrino mixing and CP violation phases in Zee-Babu model
Van Vien, Vo; Thu, Pham Ngoc
2014-01-01T23:59:59.000Z
We show that the neutrino mass matrix of the Zee-Babu model is able to fit the most recent data on neutrino masses and mixing with large $\\theta_{13}$ and provides %the values of the Dirac and Majorana CP violation phases. For the normal hierarchy, the Majorana phases ($\\al_{2 1}, \\al_{3 1}$) are equal to zero, while for the inverted pattern, one phase ($\\al_{3 1}$) takes the value $2 \\pi$. The Dirac phase ($\\de$) is predicted to either $0$ or $\\pi$. The effective mass governing neutrinoless double beta decay and the sum of neutrino masses are consistent with the recent analysis. The model gives some regions of the parameters of neutrino mixing angles in both normal and inverted neutrino mass hierarchy.
Non-Oscillation Probes of Neutrino Masses
Weinheimer, C. [Westfaelische Wilhelms-Universitaet Muenster Institut fuer Kernphysik, Wilhelm-Klemm-Str. 9, D-48149 Muenster (Germany)
2010-03-30T23:59:59.000Z
The absolute scale of neutrino masses is very important for understanding the evolution and the structure formation of the universe as well as for nuclear and particle physics beyond the present Standard Model. Complementary to deducing statements on the neutrino mass from cosmological observations, two different methods to determine the neutrino mass scale in the laboratory are pursued: the search for neutrinoless double beta decay and the direct neutrino mass search. For both methods currently experiments with a sensitivity of O(100) meV are being set up or commissioned.
CP violation in neutrino mass matrix
Utpal Sarkar; Santosh K. Singh
2006-08-03T23:59:59.000Z
We constructed rephasing invariant measures of CP violation with elements of the neutrino mass matrix, in the basis in which the charged lepton mass matrix is diagonal. We discuss some examples of neutrino mass matrices with texture zeroes, where the present approach is applicable and demonstrate how it simplifies an analysis of CP violation. We applied our approach to study CP violation in all the phenomenologically acceptable 3-generation two-zero texture neutrino mass matrices and shown that in any of these cases there is only one CP phase which contributes to the neutrino oscillation experiment and there are no Majorana phases.
Goswami, Srubabati [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India); Physik-Department, Technische Universitaet Muenchen, James-Franck-Strasse, D-85748 Garching (Germany); Rodejohann, Werner [Physik-Department, Technische Universitaet Muenchen, James-Franck-Strasse, D-85748 Garching (Germany)
2006-06-01T23:59:59.000Z
We analyze the constraints on neutrino mass spectra with extra sterile neutrinos as implied by the LSND experiment. The various mass related observables in neutrinoless double beta decay, tritium beta decay and cosmology are discussed. Both neutrino oscillation results as well as recent cosmological neutrino mass bounds are taken into account. We find that some of the allowed mass patterns are severely restricted by the current constraints, in particular, by the cosmological constraints on the total sum of neutrino masses and by the nonmaximality of the solar neutrino mixing angle. Furthermore, we estimate the form of the four neutrino mass matrices and also comment on the situation in scenarios with two additional sterile neutrinos.
Srubabati Goswami; Werner Rodejohann
2006-05-18T23:59:59.000Z
We analyze the constraints on neutrino mass spectra with extra sterile neutrinos as implied by the LSND experiment. The various mass related observables in neutrinoless double beta decay, tritium beta decay and cosmology are discussed. Both neutrino oscillation results as well as recent cosmological neutrino mass bounds are taken into account. We find that some of the allowed mass patterns are severely restricted by the current constraints, in particular by the cosmological constraints on the total sum of neutrino masses and by the non-maximality of the solar neutrino mixing angle. Furthermore, we estimate the form of the four neutrino mass matrices and also comment on the situation in scenarios with two additional sterile neutrinos.
Neutrino Majorana Mass from Black Hole
Yosuke Uehara
2002-05-25T23:59:59.000Z
We propose a new mechanism to generate the neutrino Majorana mass in TeV-scale gravity models. The black hole violates all non-gauged symmetries and can become the origin of lepton number violating processes. The fluctuation of higher-dimensional spacetime can result in the production of a black hole, which emits 2 neutrinos. If neutrinos are Majorana particles, this process is equivalent to the free propagation of a neutrino with the insertion of the black hole. From this fact, we derive the neutrino Majorana mass. The result is completely consistent with the recently observed evidence of neutrinoless double beta decay. And the obtained neutrino Majorana mass satisfies the constraint from the density of the neutrino dark matter, which affects the cosmic structure formation. Furthermore, we can explain the ultrahigh energy cosmic rays by the Z-burst scenario with it.
Minimal archi-texture for neutrino mass matrices
Atsushi Watanabe; Koichi Yoshioka
2006-03-15T23:59:59.000Z
The origin of the observed masses and mixing angles of quarks and leptons is one of imperative subjects in and beyond the standard model. Toward a deeper understanding of flavor structure, we investigate in this paper the minimality of fermion mass (Yukawa) matrices in unified theory. That is, the simplest matrix form is explored in light of the current experimental data for quarks and leptons, including the recent measurements of quark CP violation and neutrino oscillations. Two types of neutrino mass schemes are particularly analyzed; (i) Majorana masses of left-handed neutrinos with unspecified mechanism and (ii) Dirac and Majorana masses introducing three right-handed neutrinos. As a result, new classes of neutrino mass matrices are found to be consistent to the low-energy experimental data and high-energy unification hypothesis. For distinctive phenomenological implications of the minimal fermion mass textures, we discuss flavor-violating decay of charged leptons, the baryon asymmetry of the universe via thermal leptogenesis, neutrino-less double beta decay, and low-energy leptonic CP violation.
Sensitivity of neutrino mass experiments to the cosmic neutrino background
Formaggio, Joseph A.
The KATRIN neutrino experiment is a next-generation tritium beta decay experiment aimed at measuring the mass of the electron neutrino to better than 200 meV at 90% C.L. Because of its intense tritium source, KATRIN can ...
Probing the Absolute Mass Scale of Neutrinos
Prof. Joseph A. Formaggio
2011-10-12T23:59:59.000Z
The experimental efforts of the Neutrino Physics Group at MIT center primarily around the exploration of neutrino mass and its significance within the context of nuclear physics, particle physics, and cosmology. The group has played a prominent role in the Sudbury Neutrino Observatory, a neutrino experiment dedicated to measure neutrino oscillations from 8B neutrinos created in the sun. The group is now focusing its efforts in the measurement of the neutrino mass directly via the use of tritium beta decay. The MIT group has primary responsibilities in the Karlsruhe Tritium Neutrino mass experiment, expected to begin data taking by 2013. Specifically, the MIT group is responsible for the design and development of the global Monte Carlo framework to be used by the KATRIN collaboration, as well as responsibilities directly associated with the construction of the focal plane detector. In addition, the MIT group is sponsoring a new research endeavor for neutrino mass measurements, known as Project 8, to push beyond the limitations of current neutrino mass experiments.
A bound on neutrino masses from baryogenesis
W. Buchmüller; P. Di Bari; M. Plümacher
2002-09-25T23:59:59.000Z
Properties of neutrinos, the lightest of all elementary particles, may be the origin of the entire matter-antimatter asymmetry of the universe. This requires that neutrinos are Majorana particles, which are equal to their antiparticles, and that their masses are sufficiently small. Leptogenesis, the theory explaining the cosmic matter-antimatter asymmetry, predicts that all neutrino masses are smaller than 0.2 eV, which will be tested by forthcoming laboratory experiments and by cosmology.
Mass freezing in growing neutrino quintessence
Nelson J. Nunes; Lily Schrempp; Christof Wetterich
2011-05-31T23:59:59.000Z
Growing neutrino quintessence solves the coincidence problem for dark energy by a growing cosmological value of the neutrino mass which emerges from a cosmon-neutrino interaction stronger than gravity. The cosmon-mediated attraction between neutrinos induces the formation of large scale neutrino lumps in a recent cosmological epoch. We argue that the non-linearities in the cosmon field equations stop the further increase of the neutrino mass within sufficiently dense and large lumps. As a result, we find the neutrino induced gravitational potential to be substantially reduced when compared to linear extrapolations. We furthermore demonstrate that inside a lump the possible time variation of fundamental constants is much smaller than their cosmological evolution. This feature may reconcile current geophysical bounds with claimed cosmological variations of the fine structure constant.
Distinguishing Neutrino Mass Hierarchies using Dark Matter Annihilation Signals at IceCube
Rouzbeh Allahverdi; Bhaskar Dutta; Dilip Kumar Ghosh; Bradley Knockel; Ipsita Saha
2015-06-27T23:59:59.000Z
We explore the possibility of distinguishing neutrino mass hierarchies through the neutrino signal from dark matter annihilation at neutrino telescopes. We consider a simple extension of the standard model where the neutrino masses and mixing angles are obtained via the type-II seesaw mechanism. We show that for a detector with the same capability as the IceCube DeepCore array, multiyear data from DM annihilation at the Galactic Center and inside the Sun can be used to distinguish the normal and inverted neutrino mass hierarchies.
Inverted mass hierarchy from scaling in the neutrino mass matrix: Low and high energy phenomenology
Blum, A.; Rodejohann, W. [Max-Planck-Institut fuer Kernphysik, Postfach 10 39 80, D-69029 Heidelberg (Germany); Mohapatra, R. N. [Department of Physics and Maryland Center for Fundamental Physics, University of Maryland, College Park, Maryland 20742 (United States) and Sektion Physik, Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37a, D-80333 Munich (Germany) and Physik-Department, Technische Universitaet Muenchen, James-Franck-Strasse, D-85748 Garching (Germany)
2007-09-01T23:59:59.000Z
Best-fit values of recent global analyses of neutrino data imply large solar neutrino mixing, vanishing U{sub e3}, and a nonmaximal atmospheric neutrino mixing angle {theta}{sub 23}. We show that these values emerge naturally by the hypothesis of scaling in the Majorana neutrino mass matrix, which states that the ratios of its elements are equal. It also predicts an inverted hierarchy for the neutrino masses. We point out several advantages and distinguishing tests of the scaling hypothesis compared to the L{sub e}-L{sub {mu}}-L{sub {tau}} flavor symmetry, which is usually assumed to provide an understanding of the inverted hierarchy. Scenarios which have initially vanishing U{sub e3} and maximal atmospheric neutrino mixing are shown to be unlikely to lead to nonmaximal {theta}{sub 23} while simultaneously keeping U{sub e3} zero. We find a peculiar ratio of the branching ratios {mu}{yields}e{gamma} and {tau}{yields}e{gamma} in supersymmetric seesaw frameworks, which only depends on atmospheric neutrino mixing and results in {tau}{yields}e{gamma} being unobservable. The consequences of the scaling hypothesis for high energy astrophysical neutrinos at neutrino telescopes are also investigated. Then we analyze a seesaw model based on the discrete symmetry D{sub 4}xZ{sub 2} leading to scaling in the low energy mass matrix and being capable of generating the baryon asymmetry of the Universe via leptogenesis. The relevant CP phase is identical to the low energy Majorana phase, and successful leptogenesis requires an effective mass for neutrinoless double beta decay larger than 0.045 eV.
Radiative inverse seesaw neutrino mass and dark matter
Guo Gang [INPAC, Department of Physics and Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai Jiao Tong University, Shanghai (China); He Xiaogang [INPAC, Department of Physics and Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai Jiao Tong University, Shanghai (China) and Department of Physics, National Tsing Hua University, and NCTS, Hsinchu, Taiwan (China); Li Guannan [INPAC, Department of Physics and Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai Jiao Tong University, Shanghai, Taiwan (China)
2013-05-23T23:59:59.000Z
Seesaw mechanism provides a natural explanation of light neutrino masses through suppression of heavy seesaw scale. In inverse seesaw models the seesaw scale can be much lower than that in the usual seesaw models. If terms inducing seesaw masses are further induced by loop corrections, the seesaw scale can be lowered to be in the range probed by experiments at the LHC without fine tuning. This talk, presented by X-G He, discuss models constructed in a recent preprint by us (arxiv:201207.6308) in which neutrino masses are generated at two loop level through inverse seesaw mechanism. These models also naturally have dark matter candidates. Although the recent data from Xenon100 put stringent constraint on the models, they can be consistent with data on neutrino masses, mixing, dark matter relic density and direct detection.
Baringer, Philip S.
1987-05-01T23:59:59.000Z
was supported in part by the U.S. Depart- ment of Energy under Contracts Nos. W-31-109-Eng-38, DE-AC02-76ER011 12, DE-AC03-76S F000998, DE- AC02-76ER01428, and DE-AC02-84ER40125. This ex- periment was made possible by the support provided by the SLAC PEP staff... articles is followed, and page proofs are sent to authors. Tau-neutrino mass limit S. Abachi, P. Baringer, B. G. Bylsma, R. De Bonte, D. Koltick, F. J. Loeffler, E. H. Low, R. L. McIlwain, D. H. Miller, C. R. Ng, L. K. Rangan, and E. I. Shibata Purdue...
Razzaghi, N
2015-01-01T23:59:59.000Z
We propose a phenomenological model of the Dirac neutrino mass matrix based on the Fridberg-Lee neutrino mass model at a special point. In this case, the Fridberg-Lee model reduces to the Democratic mass matrix with the $S_3$ permutation family symmetry. The Democratic mass matrix has an experimentally unfavored degenerate mass spectrum on the base of tribimaximal mixing matrix. We rescue the model to find a nondegenerate mass spectrum by adding the breaking mass term as preserving the twisted Fridberg-Lee symmetry. The tribimaximal mixing matrix can be also realized. Exact tribimaximal mixing leads to $\\theta_{13}=0$. However, the results from Daya Bay and RENO experiments have established a nonzero value for $\\theta_{13}$. Keeping the leading behavior of $U$ as tribimaximal, we use Broken Democratic neutrino mass model. We characterize a perturbation mass matrix which is responsible for a nonzero $\\theta_{13}$ along with CP violation, besides the solar neutrino mass splitting has been resulted from it. We c...
On-shell renormalization of the mixing matrices in Majorana neutrino theories
Andrea A. Almasy; Bernd A. Kniehl; Alberto Sirlin
2009-04-20T23:59:59.000Z
We generalize a recently proposed on-shell approach to renormalize the Cabibbo-Kobayashi-Maskawa quark-mixing matrix to the case of an extended leptonic sector that includes Dirac and Majorana neutrinos in the framework of the seesaw mechanism. An important property of this formulation is the gauge independence of both the renormalized and bare lepton mixing matrices. Also, the texture zero in the neutrino mass matrix is preserved.
Fermion Masses and Mixings from a Minimum Principle
Rodrigo Alonso
2014-05-22T23:59:59.000Z
We analyze the structure of quark and lepton mass matrices under the hypothesis that they are determined from a minimum principle applied to a generic potential invariant under the $\\left[U(3)\\right]^5\\otimes {\\mathcal O}(3)$ flavor symmetry, acting on Standard Model fermions and right-handed neutrinos. Unlike the quark case, we show that hierarchical masses for charged leptons are naturally accompanied by degenerate Majorana neutrinos with one mixing angle close to maximal, a second potentially large, a third one necessarily small, and one maximal relative Majorana phase. The scheme presented here could be tested in the near future via neutrino-less double beta decay and cosmological measurements.
Three-Neutrino Mixing and Combined Vacuum Oscillations and MSW Transitions of Solar Neutrinos
Q. Y. Liu; S. T. Petcov
1997-02-22T23:59:59.000Z
Assuming three flavour neutrino mixing takes place in vacuum, we investigate the possibility that the solar nu_e take part in MSW transitions in the Sun due to Delta m^2_{31} from 10^{-7} eV^2 to 10^{-4} eV^2, followed by long wave length vacuum oscillations on the way to the Earth, triggered by Delta m^2_{21} (or Delta m^2_{32}) from 10^{-12} eV^2 to 10^{-10} eV^2, Delta m^2_{31} and Delta m^2_{21} (Delta m^2_{32}) being the corresponding neutrino mass squared differences. The solar nu_e survival probability is shown to be described in this case by a simple analytic expression. Depending on whether the vacuum oscillations are due to Delta m^2_{21} or Delta m^2_{32} there are two very different types of interplay between the MSW transitions and the vacuum oscillations of the solar nu_e. Performing an analysis of the most recently published solar neutrino data we have found several qualitatively new solutions of the solar neutrino problem of the hybrid MSW transitions + vacuum oscillations type. The solutions differ in the way the pp, 7Be and 8B neutrino fluxes are affected by the transitions in the Sun and the oscillations in vacuum. The specific features of the new solutions are discussed.
G. L. Fogli; E. Lisi; A. Marrone; A. Melchiorri; A. Palazzo; P. Serra; J. Silk
2004-11-17T23:59:59.000Z
In the context of three-flavor neutrino mixing, we present a thorough study of the phenomenological constraints applicable to three observables sensitive to absolute neutrino masses: The effective neutrino mass in Tritium beta decay (m_beta); the effective Majorana neutrino mass in neutrinoless double beta decay (m_2beta); and the sum of neutrino masses in cosmology (Sigma). We discuss the correlations among these variables which arise from the combination of all the available neutrino oscillation data, in both normal and inverse neutrino mass hierarchy. We set upper limits on m_beta by combining updated results from the Mainz and Troitsk experiments. We also consider the latest results on m_2beta from the Heidelberg-Moscow experiment, both with and without the lower bound claimed by such experiment. We derive upper limits on Sigma from an updated combination of data from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite and the 2 degrees Fields (2dF) Galaxy Redshifts Survey, with and without Lyman-alpha forest data from the Sloan Digital Sky Survey (SDSS), in models with a non-zero running of the spectral index of primordial inflationary perturbations. The results are discussed in terms of two-dimensional projections of the globally allowed region in the (m_beta,m_2beta,Sigma) parameter space, which neatly show the relative impact of each data set. In particular, the (in)compatibility between Sigma and m_2beta constraints is highlighted for various combinations of data. We also briefly discuss how future neutrino data (both oscillatory and non-oscillatory) can further probe the currently allowed regions.
On the description of non-unitary neutrino mixing
F. J. Escrihuela; D. V. Forero; O. G. Miranda; M. Tortola; J. W. F. Valle
2015-04-13T23:59:59.000Z
Neutrino oscillations are well established and the relevant parameters determined with good precision, except for the CP phase, in terms of a unitary lepton mixing matrix. Seesaw extensions of the Standard Model predict unitarity deviations due to the admixture of heavy isosinglet neutrinos. We provide a complete description of the unitarity and universality deviations in the light neutrino sector. Neutrino oscillation experiments involving electron or muon neutrinos and anti-neutrinos are fully described in terms of just three new real parameters and a new CP phase, in addition to the ones describing oscillations with unitary mixing. Using this formalism we describe the implications of non-unitarity for neutrino oscillations and summarize the model-independent constraints on heavy neutrino couplings that arise from current experiments.
Neutrino masses from U(1) symmetries and the Super-Kamiokande data
Smaragda Lola; Graham G. Ross
1999-02-09T23:59:59.000Z
Motivated by the Super-Kamiokande data, we revisit models with U(1) symmetries and discuss the origin of neutrino masses and mixings in such theories. We show that, in models with just three light neutrinos and a hierarchy of neutrino masses, large (2-3) mixing fixes the lepton doublet U(1) charges and is thus related to the structure of the charged lepton mass matrix. We discuss the fermion mass structure that follows from the Abelian family symmetry with an extended gauge group. Requiring that the quark and lepton masses be ordered by the family symmetry, we identify the most promising scheme. This requires large, but not necessarily maximal, mixing in the mu-tau sector and gives small e-mu mixing in the range that is required for the small angle solution of the solar neutrino deficit.
S3 x Z2 model for neutrino mass matrices
W. Grimus; L. Lavoura
2005-08-02T23:59:59.000Z
We propose a model for lepton mass matrices based on the seesaw mechanism, a complex scalar gauge singlet and a horizontal symmetry $S_3 \\times \\mathbbm{Z}_2$. In a suitable weak basis, the charged-lepton mass matrix and the neutrino Dirac mass matrix are diagonal, but the vacuum expectation value of the scalar gauge singlet renders the Majorana mass matrix of the right-handed neutrinos non-diagonal, thereby generating lepton mixing. When the symmetry $S_3$ is not broken in the scalar potential, the effective light-neutrino Majorana mass matrix enjoys $\\mu$--$\\tau$ interchange symmetry, thus predicting maximal atmospheric neutrino mixing together with $U_{e3} = 0$. A partial and less predictive form of $\\mu$--$\\tau$ interchange symmetry is obtained when the symmetry $S_3$ is softly broken in the scalar potential. Enlarging the symmetry group $S_3 \\times \\mathbbm{Z}_2$ by an additional discrete electron-number symmetry $\\mathbbm{Z}_2^{(e)}$, a more predicitive model is obtained, which is in practice indistinguishable from a previous one based on the group $D_4$.
Tachyonic Field Theory and Neutrino Mass Running
U. D. Jentschura
2012-05-01T23:59:59.000Z
In this paper three things are done. (i) We investigate the analogues of Cerenkov radiation for the decay of a superluminal neutrino and calculate the Cerenkov angles for the emission of a photon through a W loop, and for a collinear electron-positron pair, assuming the tachyonic dispersion relation for the superluminal neutrino. The decay rate of a freely propagating neutrino is found to depend on the shape of the assumed dispersion relation, and is found to decrease with decreasing tachyonic mass of the neutrino. (ii) We discuss a few properties of the tachyonic Dirac equation (symmetries and plane-wave solutions), which may be relevant for the description of superluminal neutrinos seen by the OPERA experiment, and discuss the calculation of the tachyonic propagator. (iii) In the absence of a commonly accepted tachyonic field theory, and in view of an apparent "running" of the observed neutrino mass with the energy, we write down a model Lagrangian, which describes a Yukawa-type interaction of a neutrino coupling to a scalar background field via a scalar-minus-pseudoscalar interaction. This constitutes an extension of the standard model. If the interaction is strong, then it leads to a substantial renormalization-group "running" of the neutrino mass and could potentially explain the experimental observations.
Precise Nucleosynthesis Limits on Neutrino Masses
Kimmo Kainulainen
1996-08-02T23:59:59.000Z
A computation of nucleosynthesis bounds on the masses of long-lived Dirac and Majorana neutrinos is reviewed. In particular an explicit treatment of the ``differential heating'' of the $\
Direct neutrino mass measurements after PLANCK
Formaggio, Joseph A.
The absolute mass scale of neutrinos remains an open question subject to experimental investigation from both particle physics and cosmology. Over the next decade, a number of experiments from both disciplines will attempt ...
Running of Radiative Neutrino Masses: The Scotogenic Model
Romain Bouchand; Alexander Merle
2012-04-30T23:59:59.000Z
We study the renormalization group equations of Ma's scotogenic model, which generates an active neutrino mass at 1-loop level. In addition to other benefits, the main advantage of the mechanism exploited in this model is to lead to a natural loop-suppression of the neutrino mass, and therefore to an explanation for its smallness. However, since the structure of the neutrino mass matrix is altered compared to the ordinary type I seesaw case, the corresponding running is altered as well. We have derived the full set of renormalization group equations for the scotogenic model which, to our knowledge, had not been presented previously in the literature. This set of equations reflects some interesting structural properties of the model, and it is an illustrative example for how the running of neutrino parameters in radiative models is modified compared to models with tree-level mass generation. We also study a simplified numerical example to illustrate some general tendencies of the running. Interestingly, the structure of the RGEs can be exploited such that a bimaximal leptonic mixing pattern at the high-energy scale is translated into a valid mixing pattern at low energies, featuring a large value of \\theta_{13}. This suggests very interesting connections to flavour symmetries.
United Quark and Neutrino Mixing Matrices with Universal Pair of CP-Violating Phases
E. M. Lipmanov
2008-01-21T23:59:59.000Z
The Standard Model quark and neutrino mixing matrices are of independent empirical origin, but they do suggest unification. In this paper I obtained two united one-parameter quark and neutrino mixing matrices inferred from two semi-empirical deviation-from-mass-degeneracy (DMD) flavor rules (quadratic DMD-hierarchy rule and Dirac-Majorana DMD-duality rule) without use of the common exact-flavor-symmetry suggestions for that particular unification problem. One small empirical parameter quantitatively defines the pattern of particle flavor physics. The main predictions are: 1) hierarchical connections between the 2 large solar and atmospheric neutrino mixing angels, and the 2 small quark mixing angels, 2) universal sequence of 14 equality relations to that one-empirical-parameter of the quark and neutrino mixing-matrix parameters, CP-phases and lepton mass ratios, which are free dimensionless constants in the Standard Model, 3) complementarity connections between doubled large neutrino and small quark mixing angles, 4) tentative solution of the CP-violation problem in framework of Standard Model mixing matrix phenomenology by suggesting a universal set of two nonzero values ~58.8 and ~31.2 degrees for Dirac and Majorana CP-violating phases.
Phenomenology of Neutrino Oscillations
S. M. Bilenky; C. Giunti; W. Grimus
1999-06-04T23:59:59.000Z
This review is focused on neutrino mixing and neutrino oscillations in the light of the recent experimental developments. After discussing possible types of neutrino mixing for Dirac and Majorana neutrinos and considering in detail the phenomenology of neutrino oscillations in vacuum and matter, we review all existing evidence and indications in favour of neutrino oscillations that have been obtained in the atmospheric, solar and LSND experiments. We present the results of the analyses of the neutrino oscillation data in the framework of mixing of three and four massive neutrinos and investigate possibilities to test the different neutrino mass and mixing schemes obtained in this way. We also discuss briefly future neutrino oscillation experiments.
SO(3) Gauge Symmetry and Nearly Tri-bimaximal Neutrino Mixing
Yue-Liang Wu
2008-07-24T23:59:59.000Z
In this note I mainly focus on the neutrino physics part in my talk and report the most recent progress made in \\cite{YLW0}. It is seen that the Majorana features of neutrinos and SO(3) gauge flavor symmetry can simultaneously explain the smallness of neutrino masses and nearly tri-bimaximal neutrino mixing when combining together with the mechanism of approximate global U(1) family symmetry. The mixing angle $\\theta_{13}$ and CP-violating phase are in general nonzero and testable experimentally at the allowed sensitivity. The model also predicts the existence of vector-like Majorana neutrinos and charged leptons as well as new Higgs bosons, some of them can be light and explored at the LHC and ILC.
Neutrinoless double-beta decay with three or four neutrino mixing
C. Giunti
1999-08-27T23:59:59.000Z
Considering the scheme with mixing of three neutrinos and a mass hierarchy that can accommodate the results of solar and atmospheric neutrino experiments, it is shown that the results of solar neutrino experiments imply a lower bound for the effective Majorana mass in neutrinoless double-beta decay, under the natural assumptions that massive neutrinos are Majorana particles and there are no unlikely fine-tuned cancellations among the contributions of the different neutrino masses. Considering the four-neutrino schemes that can accommodate also the results of the LSND experiment, it is shown that only one of them is compatible with the results of neutrinoless double-beta decay experiments and with the measurement of the abundances of primordial elements produced in Big-Bang Nucleosynthesis. It is shown that in this scheme, under the assumptions that massive neutrinos are Majorana particles and there are no cancellations among the contributions of the different neutrino masses, the results of the LSND experiment imply a lower bound for the effective Majorana mass in neutrinoless double-beta decay.
Three-Neutrino Mixing and Combined Vacuum Oscillations and MSW Transitions of Solar Neutrinos
Liu, Q Y
1997-01-01T23:59:59.000Z
Assuming three flavour neutrino mixing takes place in vacuum, we investigate the possibility that the solar nu_e take part in MSW transitions in the Sun due to Delta m^2_{31} from 10^{-7} eV^2 to 10^{-4} eV^2, followed by long wave length vacuum oscillations on the way to the Earth, triggered by Delta m^2_{21} (or Delta m^2_{32}) from 10^{-12} eV^2 to 10^{-10} eV^2, Delta m^2_{31} and Delta m^2_{21} (Delta m^2_{32}) being the corresponding neutrino mass squared differences. The solar nu_e survival probability is shown to be described in this case by a simple analytic expression. Depending on whether the vacuum oscillations are due to Delta m^2_{21} or Delta m^2_{32} there are two very different types of interplay between the MSW transitions and the vacuum oscillations of the solar nu_e. Performing an analysis of the most recently published solar neutrino data we have found several qualitatively new solutions of the solar neutrino problem of the hybrid MSW transitions + vacuum oscillations type. The solutions ...
Study of the neutrino mass hierarchy with the atmospheric neutrino data observed in Super-Kamiokande
Tokyo, University of
Study of the neutrino mass hierarchy with the atmospheric neutrino data observed in Super-Kamiokande analysis carried out with Super- Kamiokande atmospheric neutrino data in order to obtain information-neutrino enriched event samples from the Super-Kamiokande atmospheric neutrino data. Super-Kamiokande is a 50 kton
Solar mass-varying neutrino oscillations
Marfatia, Danny; Huber, P.; Barger, V.
2005-11-18T23:59:59.000Z
on the nucleon number density n N . (2) The n e and n N distribu- tions in the Sun do not have the same shape [10]. Nonetheless, this simplification suffices for our purposes. Tests of the gravitational inverse square law require the coupling of a scalar..., the neutrino overdensity in the Milky Way from gravitational clustering can be neglected [7]. Then,m .0023 i essentially represent the masses of terrestrial neutrinos in laboratory experiments like those measuring tritium beta decay. Since the neutrinos under...
Zero minors of the neutrino mass matrix
Lashin, E. I. [Abdus Salam ICTP, P.O. Box 586, 34100 Trieste (Italy); Ain Shams University, Faculty of Science, Cairo 11566 (Egypt); Department of Physics and Astronomy, College of Science, King Saud University, Riyadh (Saudi Arabia); Chamoun, N. [Abdus Salam ICTP, P.O. Box 586, 34100 Trieste (Italy); Physics Department, HIAST, P.O. Box 31983, Damascus (Syrian Arab Republic)
2008-10-01T23:59:59.000Z
We examine the possibility that a certain class of neutrino mass matrices, namely, those with two independent vanishing minors in the flavor basis, regardless of being invertible or not, is sufficient to describe current data. We compute generic formulas for the ratios of the neutrino masses and for the Majorana phases. We find that seven textures with two vanishing minors can accommodate the experimental data. We present an estimate of the mass matrix for these patterns. All of the possible textures can be dynamically generated through the seesaw mechanism augmented with a discrete Abelian symmetry.
Neutrino Physics, Superbeams, and the Neutrino Factory
Boris Kayser
2003-06-09T23:59:59.000Z
We summarize what has been learned about the neutrino mass spectrum and neutrino mixing, identify interesting open questions that can be answered by accelerator neutrino facilities of the future, and discuss the importance and physics of answering them.
Testing solar lepton mixing sum rules in neutrino oscillation experiments
Ballett, Peter; Luhn, Christoph; Pascoli, Silvia; Schmidt, Michael A
2014-01-01T23:59:59.000Z
Small discrete family symmetries such as S4, A4 or A5 may lead to simple leading-order predictions for the neutrino mixing matrix such as the bimaximal, tribimaximal or golden ratio mixing patterns, which may be brought into agreement with experimental data with the help of corrections from the charged-lepton sector. Such scenarios generally lead to relations among the parameters of the physical leptonic mixing matrix known as solar lepton mixing sum rules. In this article, we present a simple derivation of such solar sum rules, valid for arbitrary neutrino and charged lepton mixing angles and phases, assuming only {\\theta}13^{\
Five Years of Neutrino Physics with Super-Kamiokande
M. B. Smy
2002-06-07T23:59:59.000Z
Using data from both solar and atmospheric neutrinos, Super-Kamiokande has provided fundamental information on neutrino flavor mixing and neutrino mass square differences.
Neutrino mixing schemes and neutrinoless double beta decay
H. V. Klapdor-Kleingrothaus; U. Sarkar
2002-02-22T23:59:59.000Z
We study the possible structure of the neutrino mass matrix taking into consideration the solar and atmospheric neutrinos and the neutrinoless double beta decay. We emphasize on mass matrices with vanishing elements. There are only a very few possibilities remaining at present. We concentrate on three generation scenarios and find that with three parameters there are few possibilities with and without any vanishing elements. For completeness we also present a five parameter four neutrino (with one sterile neutrino) mass matrix which can explain all these experiments and the LSND result.
Neutrino mass matrix solutions and neutrinoless double beta decay
Thomas Hambye
2002-01-31T23:59:59.000Z
We present a determination of the neutrino mass matrix which holds for values of the neutrinoless double beta decay effective mass m_{ee} larger than the neutrino mass differences. We find eight possible solutions and discuss for each one the corresponding neutrino mass eigenvalues and zero texture. A minimal structure of the perturbations to add to these zero textures to recover the full mass matrix is also determined. Implications for neutrino hot dark matter are discussed for each solution.
Neutrinoless Double Beta Decay and Neutrino Masses
Michael Duerr
2012-06-04T23:59:59.000Z
Neutrinoless double beta decay is a promising test for lepton number violating physics beyond the standard model of particle physics. There is a deep connection between this decay and the phenomenon of neutrino masses. In particular, we will discuss the relation between neutrinoless double beta decay and Majorana neutrino masses provided by the so-called Schechter--Valle theorem in a quantitative way. Furthermore, we will present an experimental cross check to discriminate neutrinoless double beta decay from unknown nuclear background using only one isotope, i.e., within one experiment.
Neutrinoless double beta decay and neutrino masses
Duerr, Michael [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)
2012-07-27T23:59:59.000Z
Neutrinoless double beta decay (0{nu}{beta}{beta}) is a promising test for lepton number violating physics beyond the standard model (SM) of particle physics. There is a deep connection between this decay and the phenomenon of neutrino masses. In particular, we will discuss the relation between 0{nu}{beta}{beta} and Majorana neutrino masses provided by the so-called Schechter-Valle theorem in a quantitative way. Furthermore, we will present an experimental cross check to discriminate 0{nu}{beta}{beta} from unknown nuclear background using only one isotope, i.e., within one experiment.
Neutrino oscillations: brief history and present status
Bilenky, S M
2014-01-01T23:59:59.000Z
A brief review of the problem of neutrino masses and oscillations is given. In the beginning we present an early history of neutrino masses, mixing and oscillations. Then we discuss all possibilities of neutrino masses and mixing (neutrino mass terms). The phenomenology of neutrino oscillations in vacuum is considered in some details. We present also the neutrino oscillation data and the seesaw mechanism of the neutrino mass generation.
Common origin of reactor and sterile neutrino mixing
Alexander Merle; Stefano Morisi; Walter Winter
2014-06-19T23:59:59.000Z
If the hints for light sterile neutrinos from short-baseline anomalies are to be taken seriously, global fits indicate active-sterile mixings of a magnitude comparable to the known reactor mixing. We therefore study the conditions under which the active-sterile and reactor mixings could have the same origin in an underlying flavour model. As a starting point, we use $\\mu-\\tau$ symmetry in the active neutrino sector, which (for three neutrinos) yields a zero reactor neutrino angle and a maximal atmospheric one. We demonstrate that adding one sterile neutrino can change this setting, so that the active-sterile mixing and non-zero $\\theta_{13}$ can be generated simultaneously. From the phenomenological perspective, electron (anti)neutrino disappearance can be easily accommodated, while muon neutrino disappearance can vanish. It is, however, difficult to reconcile the LSND results with this scenario. From the theory perspective, the setting requires the misalignment of some of the flavon vacuum expectation values, which may be achieved in an $A_4$ or $D_4$ flavour symmetry model using extra dimensions.
Double beta decay and neutrino mass models
Helo, J C; Ota, T; Santos, F A Pereira dos
2015-01-01T23:59:59.000Z
Neutrinoless double beta decay allows to constrain lepton number violating extensions of the standard model. If neutrinos are Majorana particles, the mass mechanism will always contribute to the decay rate, however, it is not a priori guaranteed to be the dominant contribution in all models. Here, we discuss whether the mass mechanism dominates or not from the theory point of view. We classify all possible (scalar-mediated) short-range contributions to the decay rate according to the loop level, at which the corresponding models will generate Majorana neutrino masses, and discuss the expected relative size of the different contributions to the decay rate in each class. We also work out the phenomenology of one concrete 2-loop model in which both, mass mechanism and short-range diagram, might lead to competitive contributions, in some detail.
Experiments for the absolute neutrino mass measurement
Markus Steidl
2009-06-02T23:59:59.000Z
Experimental results and perspectives of different methods to measure the absolute mass scale of neutrinos are briefly reviewed. The mass sensitivities from cosmological observations, double beta decay searches and single beta decay spectroscopy differ in sensitivity and model dependance. Next generation experiments in the three fields reach the sensitivity for the lightest mass eigenstate of $m_1<0.2eV$, which will finally answer the question if neutrino mass eigenstates are degenerate. This sensitivity is also reached by the only model-independent approach of single beta decay (KATRIN experiment). For higher sensitivities on cost of model-dependance the neutrinoless double beta decay search and cosmological observation have to be applied. Here, in the next decade sensitivities are approached with the potential to test inverted hierarchy models.
Monika Sinha; Banibrata Mukhopadhyay
2007-11-21T23:59:59.000Z
We study the consequences of CPT and lepton number violation in neutrino sector. For CPT violation we take gravity with which neutrino and antineutrino couple differently. Gravity mixes neutrino and antineutrino in an unequal ratio to give two mass eigenstates. Lepton number violation interaction together with CPT violation gives rise to neutrino-antineutrino oscillation. Subsequently, we study the neutrino flavor mixing and oscillation under the influence of gravity. It is found that gravity changes flavor oscillation significantly which influences the relative abundance of different flavors in present universe. We show that the neutrinoless double beta decay rate is modified due to presence of gravity- the origin of CPT violation, as the mass of the flavor state is modified.
Asan Damanik
2010-11-25T23:59:59.000Z
Neutrino mass matrix via a seesaw mechanism is constructed by assuming that the underlying symmetry of both heavy Majorana and Dirac mass matrices is the discrete subgroup $\\Delta(27)$ symmetry of SU(3). Using the experimental data of neutrino oscillation, the neutrino mass matrix exhibits maximal $\
Double beta decay, Majorana neutrinos, and neutrino mass
Avignone, Frank T. III; Elliott, Steven R.; Engel, Jonathan [Department of Physics and Astronomy, University of South Carolina, Columbia, South Carolina 29208 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599-3255 (United States)
2008-04-15T23:59:59.000Z
The theoretical and experimental issues relevant to neutrinoless double beta decay are reviewed. The impact that a direct observation of this exotic process would have on elementary particle physics, nuclear physics, astrophysics, and cosmology is profound. Now that neutrinos are known to have mass and experiments are becoming more sensitive, even the nonobservation of neutrinoless double beta decay will be useful. If the process is actually observed, we will immediately learn much about the neutrino. The status and discovery potential of proposed experiments are reviewed in this context, with significant emphasis on proposals favored by recent panel reviews. The importance of and challenges in the calculation of nuclear matrix elements that govern the decay are considered in detail. The increasing sensitivity of experiments and improvements in nuclear theory make the future exciting for this field at the interface of nuclear and particle physics.
Double Beta Decay, Majorana Neutrinos, and Neutrino Mass
Frank T. Avignone III; Steven R. Elliott; Jonathan Engel
2007-11-26T23:59:59.000Z
The theoretical and experimental issues relevant to neutrinoless double-beta decay are reviewed. The impact that a direct observation of this exotic process would have on elementary particle physics, nuclear physics, astrophysics and cosmology is profound. Now that neutrinos are known to have mass and experiments are becoming more sensitive, even the non-observation of neutrinoless double-beta decay will be useful. If the process is actually observed, we will immediately learn much about the neutrino. The status and discovery potential of proposed experiments are reviewed in this context, with significant emphasis on proposals favored by recent panel reviews. The importance of and challenges in the calculation of nuclear matrix elements that govern the decay are considered in detail. The increasing sensitivity of experiments and improvements in nuclear theory make the future exciting for this field at the interface of nuclear and particle physics.
Dirac or inverse seesaw neutrino masses with B – L gauge symmetry and S? flavor symmetry
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Ma, Ernest; Srivastava, Rahul
2015-02-01T23:59:59.000Z
Many studies have been made on extensions of the standard model with B – L gauge symmetry. The addition of three singlet (right-handed) neutrinos renders it anomaly-free. It has always been assumed that the spontaneous breaking of B – L is accomplished by a singlet scalar field carrying two units of B – L charge. This results in a very natural implementation of the Majorana seesaw mechanism for neutrinos. However, there exists in fact another simple anomaly-free solution which allows Dirac or inverse seesaw neutrino masses. We show for the first time these new possibilities and discuss an application tomore »neutrino mixing with S? flavor symmetry.« less
High energy neutrino telescopes as a probe of the neutrino mass mechanism
Kfir Blum; Anson Hook; Kohta Murase
2014-08-17T23:59:59.000Z
We show that measurements of the spectral shape and flavor ratios of high energy astrophysical neutrinos at neutrino telescopes can be sensitive to the details of the neutrino mass mechanism. We propose a simple model for Majorana neutrino mass generation that realizes the relevant parameter space, in which small explicit lepton number violation is mediated to the Standard Model through the interactions of a light scalar. IceCube, with about ten years of exposure time, could reveal the presence of anomalous neutrino self-interactions. Precision electroweak and lepton flavor laboratory experiments and a determination of the total neutrino mass from cosmology would provide consistency checks on the interpretation of a signal.
Compromise between neutrino masses and collider signatures in the type-II seesaw model
Chao Wei; Luo Shu; Xing Zhizhong; Zhou Shun [Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918, Beijing 100049 (China)
2008-01-01T23:59:59.000Z
A natural extension of the standard SU(2){sub L}xU(1){sub Y} gauge model to accommodate massive neutrinos is to introduce one Higgs triplet and three right-handed Majorana neutrinos, leading to a 6x6 neutrino mass matrix which contains three 3x3 submatrices, M{sub L}, M{sub D} and M{sub R}. We show that three light Majorana neutrinos (i.e., the mass eigenstates of {nu}{sub e}, {nu}{sub {mu}}, and {nu}{sub {tau}}) are exactly massless in this model, if and only if M{sub L}=M{sub D}M{sub R}{sup -1}M{sub D}{sup T} exactly holds. This no-go theorem implies that small but nonvanishing neutrino masses may result from a significant but incomplete cancellation between M{sub L} and M{sub D}M{sub R}{sup -1}M{sub D}{sup T} terms in the Type-II seesaw formula, provided three right-handed Majorana neutrinos are of O(1) TeV and experimentally detectable at the LHC. We propose three simple Type-II seesaw scenarios with the A{sub 4}xU(1){sub X} flavor symmetry and its explicit breaking to interpret the observed neutrino mass spectrum and neutrino mixing pattern. Such a TeV-scale neutrino model can be tested in two complementary ways: (1) searching for possible collider signatures of lepton number violation induced by the right-handed Majorana neutrinos and doubly-charged Higgs particles; and (2) searching for possible consequences of unitarity violation of the 3x3 neutrino mixing matrix in the future long-baseline neutrino oscillation experiments.
Permutation symmetry for neutrino and charged-lepton mass matrices
Ma, Ernest [Physics Department, Univeristy of California, Riverside, California 92521 (United States)] [Physics Department, Univeristy of California, Riverside, California 92521 (United States)
2000-02-01T23:59:59.000Z
Permutation symmetry S{sub 3} is applied to obtain two equal Majorana neutrino masses, while maintaining three different charged-lepton masses and suppressing neutrinoless double beta decay. The resulting radiative splitting of the two neutrinos is shown to be suitable for solar neutrino vacuum oscillations. (c) 2000 The American Physical Society.
Measurable neutrino mass scale in A{sub 4}xSU(5)
Antusch, S.; Spinrath, M. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, D-80805 Muenchen (Germany); King, Stephen F. [School of Physics and Astronomy, University of Southampton, SO17 1BJ Southampton (United Kingdom)
2011-01-01T23:59:59.000Z
We propose a supersymmetric A{sub 4}xSU(5) model of quasidegenerate neutrinos which predicts the effective neutrino mass m{sub ee} relevant for neutrinoless double beta decay to be proportional to the neutrino mass scale, thereby allowing its determination approximately independently of unknown Majorana phases. Such a natural quasidegeneracy is achieved by using A{sub 4} family symmetry (as an example of a non-Abelian family symmetry with real triplet representations) to enforce a contribution to the neutrino mass matrix proportional to the identity. Tribimaximal neutrino mixing as well as quark CP violation with {alpha}{approx_equal}90 deg. d a leptonic CP phase {delta}{sub MNS{approx_equal}}90 deg. arise from the breaking of the A{sub 4} family symmetry by the vacuum expectation values of four 'flavon' fields pointing in specific postulated directions in flavor space.
Improving constraints on the neutrino mass using sufficient statistics
Wolk, M; Bel, J; Carbone, C; Carron, J
2015-01-01T23:59:59.000Z
We use the "Dark Energy and Massive Neutrino Universe" (DEMNUni) simulations to compare the constraining power of "sufficient statistics" with the standard matter power spectrum on the sum of neutrino masses, $M_\
Neutrino masses, cosmological bound and four zero Yukawa textures
Biswajit Adhikary; Ambar Ghosal; Probir Roy
2011-10-18T23:59:59.000Z
Four zero neutrino Yukawa textures in a specified weak basis, combined with $\\mu\\tau$ symmetry and type-I seesaw, yield a highly constrained and predictive scheme. Two alternately viable $3\\times3$ light neutrino Majorana mass matrices $m_{\
Neutrinoless double beta decay, solar neutrinos and mass scales
Per Osland; Geir Vigdel
2001-09-13T23:59:59.000Z
We obtain bounds for the neutrino masses by combining atmospheric and solar neutrino data with the phenomenology of neutrinoless double beta decay where hypothetical values of || are envisaged from future 0\
Neutrino masses, cosmological bound and four zero Yukawa textures
Adhikary, Biswajit; Roy, Probir
2011-01-01T23:59:59.000Z
Four zero neutrino Yukawa textures in a specified weak basis, combined with $\\mu\\tau$ symmetry and type-I seesaw, yield a highly constrained and predictive scheme. Two alternately viable $3\\times3$ light neutrino Majorana mass matrices $m_{\
Examining the geometrical model with inverted mass hierarchy for neutrinos
Honda, Mizue; Tanimoto, Morimitsu [Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan); Department of Physics, Niigata University, Niigata 950-2181 (Japan)
2007-05-01T23:59:59.000Z
The comprehensive analyses are presented in the model with the inverted mass hierarchy for neutrinos, which follows from a geometrical structure of a (1+5) dimensional space-time where two extra dimensions are compactified on the T{sup 2}/Z{sub 3} orbifold. The model gives two large lepton flavor mixings due to the S{sub 3} structure in the (1+5) dimensional space-time. It also predicts the lightest neutrino mass as m{sub 3}=(1-50)x10{sup -5} eV and the effective neutrino mass responsible for neutrinoless double beta decays as
Neutrino mass matrices with one texture zero and a vanishing neutrino mass
Gautam, Radha Raman; Gupta, Manmohan
2015-01-01T23:59:59.000Z
Assuming Majorana nature of neutrinos, we investigate the singular one texture zero neutrino mass matrices in the flavor basis. We find that for the normal mass ordering with $m_1=0$, all the six one texture zero classes are now ruled out at 3$\\sigma$ confidence level, whereas for inverted mass ordering with $m_3=0$ only four classes out of total six can accommodate the latest neutrino oscillation data at 3$\\sigma$ confidence level. Moreover, only two classes can accommodate the present data at 1$\\sigma$ confidence level. We examine the phenomenological implications of the allowed classes for the effective Majorana mass, Dirac and Majorana CP-violating phases. Working within the framework of type-I seesaw mechanism, we present simple discrete Abelian symmetry models leading to all the phenomenologically allowed classes.
Neutrino mass matrices with one texture zero and a vanishing neutrino mass
Radha Raman Gautam; Madan Singh; Manmohan Gupta
2015-06-16T23:59:59.000Z
Assuming Majorana nature of neutrinos, we investigate the singular one texture zero neutrino mass matrices in the flavor basis. We find that for the normal mass ordering with $m_1=0$, all the six one texture zero classes are now ruled out at 3$\\sigma$ confidence level, whereas for inverted mass ordering with $m_3=0$ only four classes out of total six can accommodate the latest neutrino oscillation data at 3$\\sigma$ confidence level. Moreover, only two classes can accommodate the present data at 1$\\sigma$ confidence level. We examine the phenomenological implications of the allowed classes for the effective Majorana mass, Dirac and Majorana CP-violating phases. Working within the framework of type-I seesaw mechanism, we present simple discrete Abelian symmetry models leading to all the phenomenologically allowed classes.
Neutrinoless double beta decay and direct searches for neutrino mass
Craig Aalseth; Henning Back; Loretta Dauwe; David Dean; Guido Drexlin; Yuri Efremenko; Hiro Ejiri; Steven Elliott; Jon Engel; Brian Fujikawa; Reyco Henning; G. W. Hoffmann; Karol Lang; Kevin Lesko; Tadafumi Kishimoto; Harry Miley; Rick Norman; Silvia Pascoli; Serguey Petcov; Andreas Piepke; Werner Rodejohann; David Saltzberg; Sean Sutton; Petr Vogel; Ray Warner; John Wilkerson; Lincoln Wolfenstein
2004-12-21T23:59:59.000Z
Study of the neutrinoless double beta decay and searches for the manifestation of the neutrino mass in ordinary beta decay are the main sources of information about the absolute neutrino mass scale, and the only practical source of information about the charge conjugation properties of the neutrinos. Thus, these studies have a unique role in the plans for better understanding of the whole fast expanding field of neutrino physics.
Two-parameter neutrino mass matrices with two texture zeros
W. Grimus; P. O. Ludl
2013-02-14T23:59:59.000Z
We reanalyse Majorana-neutrino mass matrices M_nu with two texture zeros, by searching for viable hybrid textures in which the non-zero matrix elements of M_nu have simple ratios. Referring to the classification scheme of Frampton, Glashow and Marfatia, we find that the mass matrix denoted by A1 allows the ratios (M_nu)_{mu mu} : (Mnu)_{tau tau} = 1:1 and (M_nu)_{e tau} : (Mnu)_{mu tau} = 1:2. There are analogous ratios for texture A2. With these two hybrid textures, one obtains, for instance, good agreement with the data if one computes the three mixing angles in terms of the experimentally determined mass-squared differences Delta m^2_21 and Delta m^2_31. We could not find viable hybrid textures based on mass matrices different from those of cases A1 and A2.
Two-parameter neutrino mass matrices with two texture zeros
Grimus, W
2012-01-01T23:59:59.000Z
We reanalyse Majorana-neutrino mass matrices M_nu with two texture zeros, by searching for viable hybrid textures in which the non-zero matrix elements of M_nu have simple ratios. Referring to the classification scheme of Frampton, Glashow and Marfatia, we find that the mass matrix denoted by A1 allows the ratios (M_nu)_{mu mu} : (Mnu)_{tau tau} = 1:1 and (M_nu)_{e tau} : (Mnu)_{mu tau} = 1:2. There are analogous ratios for texture A2. With these two hybrid textures, one obtains, for instance, good agreement with the data if one computes the three mixing angles in terms of the experimentally determined mass-squared differences Delta m^2_21 and Delta m^2_31. We could not find viable hybrid textures based on mass matrices different from those of cases A1 and A2.
Electroweak model of lepton mass and mixing hierarchies
E. M. Lipmanov
2009-04-06T23:59:59.000Z
Flavor physics, like cosmology, is likely in need of new basic ideas; the puzzles of elementary particle mass hierarchies and in particular the e-mu-tau and neutrino ones still remain mysteries. In this paper a new idea of dynamical connection between low energy 3-flavor particle mass hierarchies and electroweak charges is studied with restriction to the simplest case of lepton flavor phenomenology. The main inference is that it can be only two types of lepton 3-flavor particle-copy groups: 1) with large and strongly hierarchical mass ratios and 2) with close to 1 mass ratios. From experimental data definitely follows that the three charged leptons belong to the first type whereas the three neutrinos belong to the second type and so are quasi-degenerate. The inferences of QD-neutrinos with realistic small masses and oscillation hierarchy parameter and quark-QD-neutrino mixing angle complementarity follow from the fact of small EW charges and their relation to the concept of benchmark flavor pattern.
Experimental Neutrino Physics: Final Report
Lane, Charles E.; Maricic, Jelena
2012-09-05T23:59:59.000Z
Experimental studies of neutrino properties, with particular emphasis on neutrino oscillation, mass and mixing parameters. This research was pursued by means of underground detectors for reactor anti-neutrinos, measuring the flux and energy spectra of the neutrinos. More recent investigations have been aimed and developing detector technologies for a long-baseline neutrino experiment (LBNE) using a neutrino beam from Fermilab.
NOvA and T2K: The Race for the neutrino mass hierarchy
Mena, Olga; /Fermilab; Nunokawa, Hiroshi; /Rio de Janeiro, Pont. U. Catol.; Parke, Stephen J.; /Fermilab
2006-09-01T23:59:59.000Z
The determination of the ordering of the neutrino masses (the hierarchy) is probably a crucial prerequisite to understand the origin of lepton masses and mixings and to establish their relationship to the analogous properties in the quark sector. Here, we follow an alternative strategy to the usual neutrino-antineutrino comparison in long baseline neutrino oscillation experiments: we exploit the combination of the neutrino-only data from the NOvA and the T2K experiments by performing these two off-axis experiments at different distances but at the same
Neutrinoless Double Beta Decay with Negligible Neutrino Mass
Biswajoy Brahmachari; Ernest Ma
2002-02-27T23:59:59.000Z
If the electron neutrino has an effective nonzero Majorana mass, then neutrinoless double beta decay will occur. However, the latter is possible also with a negligible neutrino mass. We show how this may happen in a simple model of scalar diquarks and dileptons. This possibility allows neutrino masses to be small and hierarchical, without conflicting with the possible experimental evidence of neutrinoless double beta decay.
Chan, Yat-Long; Tsui, Ka Ming; Wong, Chan Fai; Xu, Jianyi
2015-01-01T23:59:59.000Z
We derive the neutrino flavor transition probabilities with the neutrino treated as a wave packet. The decoherence and dispersion effects from the wave-packet treatment show up as damping and phase-shifting of the plane-wave neutrino oscillation patterns. If the energy uncertainty in the initial neutrino wave packet is larger than around 0.01 of the neutrino energy, the decoherence and dispersion effects would degrade the sensitivity of reactor neutrino experiments to mass hierarchy measurement to lower than 3 $\\sigma$ confidence level.
Aspects of Neutrino Masses and Lepton-Number Violation in the light of the Super-Kamiokande data
Smaragda Lola
1999-03-01T23:59:59.000Z
We discuss aspects of neutrino masses and lepton-number violation, in the light of the observations of Super-Kamiokande. As a first step, we use the data from various experiments, in order to obtain a phenomenological understanding of neutrino mass textures. We then investigate how the required patterns of neutrino masses and mixings are related to the flavour structure of the underlying theory. In supersymmetric extensions of the Standard Model, renormalisation group effects can have important implications: for small tanb, bottom-tau unification indicates the presence of significant muon-tau flavour mixing. The evolution of the neutrino mixing may be described by simple semi-analytic expressions, which confirm that, for large tanb, very small mixing at the GUT scale may be amplified to maximal mixing at low energies, and vice versa. Passing to specific models, we first discuss the predictions for neutrino masses in different GUT models (including superstring-embedded solutions). Imposing the requirement for successful leptogenesis may give additional constraints on the generic structure of the neutrino mass textures. Finally, we discuss direct ways to look for lepton-number violation in ultra-high energy neutrino interactions.
Geometric gravitational origin of neutrino oscillations and mass-energy
Gustavo R. Gonzalez-Martin
2014-05-21T23:59:59.000Z
A mass-energy scale for neutrinos was calculated from the null cone curvature using geometric concepts. The scale is variable depending on the gravitational potential and the trajectory inclination with respect to the field direction. The proposed neutrino covariant equation provides the adequate curvature. The mass-energy at the Earth surface varies from a horizontal value 0.402 eV to a vertical value 0.569 eV. Earth spinor waves with winding numbers n show squared energy differences within ranges from 2.05 x 10*(-3) to 4.10 x 10*(-3) eV*2 for n=0,1 neutrinos and from 3.89 x 10*(-5) to 7.79 x 10*(-5) eV*2 for n=1,2 neutrinos. These waves interfere and the different phase velocities produce neutrino-like oscillations. The experimental results for atmospheric and solar neutrino oscillation mass parameters respectivelly fall within these theoretical ranges. Neutrinos in outer space, where interactions may be neglected, appear as particles travelling with zero mass on null geodesics. These gravitational curvature energies are consistent with neutrino oscillations, zero neutrino rest masses and Einstein's General Relativity and energy mass equivalence principle. When analyzing or averaging experimental neutrino mass-energy results of different experiments on the Earth it is of interest to consider the possible influence of the trajectory inclination angle.
A Model of Neutrino Mass Matrix With $?= -?/2$ and $?_{23} = ?/4$
Xiao-Gang He
2015-04-09T23:59:59.000Z
Experimental data have provided stringent constraints on neutrino mixing parameters. In the standard parametrization the mixing angle $\\theta_{23}$ is close to $\\pi/4$. There are evidences show that the CP violating phase is close to $-\\pi/2$. We study neutrino mass matrix reconstructed using this information and find several interesting properties. We show that a theoretical model based on the $A_4$ symmetry naturally predicts $\\delta = -\\pi/2$ and $\\theta_{23} = \\pi/4$. In this model, CP violation can be solely come from the complex group theoretical C-G coefficients. $|V_{e2}|$ is predicted to be $1/\\sqrt{3}$ consistent with data. This matrix can be taken as the lowest order neutrino mass matrix for theoretical model buildings. We also study deviations from the lowest order mixing matrix expansion in the model.
Majorana neutrino mass matrices with three texture zeros and the sterile neutrino
Zhang, Yongchao
2013-01-01T23:59:59.000Z
As a consequence of the LSND anomaly and other hints of an eV scale sterile neutrino from particle physics and cosmology, the neutrino sector of the standard model of particle physics has to be extended and the smallest extension is the (3+1) model, i.e. three active neutrinos plus one sterile one. In this work we study the neutrino mass matrix $M_\
Strong thermal leptogenesis and the absolute neutrino mass scale
Bari, Pasquale Di; King, Sophie E.; Fiorentin, Michele Re, E-mail: pdb1d08@soton.ac.uk, E-mail: sk1806@soton.ac.uk, E-mail: m.re-fiorentin@soton.ac.uk [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom)
2014-03-01T23:59:59.000Z
We show that successful strong thermal leptogenesis, where the final asymmetry is independent of the initial conditions and in particular a large pre-existing asymmetry is efficiently washed-out, favours values of the lightest neutrino mass m{sub 1}?>10 meV for normal ordering (NO) and m{sub 1}?>3 meV for inverted ordering (IO) for models with orthogonal matrix entries respecting |?{sub ij}{sup 2}|?<2. We show analytically why lower values of m{sub 1} require a higher level of fine tuning in the seesaw formula and/or in the flavoured decay parameters (in the electronic for NO, in the muonic for IO). We also show how this constraint exists thanks to the measured values of the neutrino mixing angles and could be tightened by a future determination of the Dirac phase. Our analysis also allows us to place a more stringent constraint for a specific model or class of models, such as SO(10)-inspired models, and shows that some models cannot realise strong thermal leptogenesis for any value of m{sub 1}. A scatter plot analysis fully supports the analytical results. We also briefly discuss the interplay with absolute neutrino mass scale experiments concluding that they will be able in the coming years to either corner strong thermal leptogenesis or find positive signals pointing to a non-vanishing m{sub 1}. Since the constraint is much stronger for NO than for IO, it is very important that new data from planned neutrino oscillation experiments will be able to solve the ambiguity.
Petcov, S.T.; Rodejohann, W. [Scuola Internazionale Superiore di Studi Avanzati, Via Beirut 2-4, I-34014 Trieste, Italy and Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34014 Trieste (Italy)
2005-04-01T23:59:59.000Z
The Pontecorvo-Maki-Nakagawa-Sakata neutrino mixing matrix is given, in general, by the product of two unitary matrices associated with the diagonalization of the charged lepton and neutrino mass matrices. Assuming that the active flavor neutrinos possess a Majorana mass matrix which is diagonalized by a bimaximal mixing matrix, we give the allowed forms of the charged lepton mixing matrix and the corresponding implied forms of the charged lepton mass matrix. We then assume that the origin of bimaximal mixing is a weakly broken flavor symmetry corresponding to the conservation of the nonstandard lepton charge L{sup '}=L{sub e}-L{sub {mu}}-L{sub {tau}}. The latter does not predict, in general, the atmospheric neutrino mixing to be maximal. We study the impact of this fact on the allowed forms of the charged lepton mixing matrix and on the neutrino mixing observables, analyzing the case of CP violation in detail. When compared with the case of exact bimaximal mixing, the deviations from zero U{sub e3} and from maximal atmospheric neutrino mixing are typically more sizable if one assumes just L{sup '} conservation. In fact, |U{sub e3}|{sup 2} can be as small as 0.007 and atmospheric neutrino mixing can take any value inside its currently allowed range. We discuss under which conditions the atmospheric neutrino mixing angle is larger or smaller than {pi}/4. We present also a simple seesaw realization of the implied light neutrino Majorana mass matrix and consider leptogenesis in this scenario.
Models of Neutrino Mass with a Low Cutoff Scale
Hooman Davoudiasl; Ryuichiro Kitano; Graham D. Kribs; Hitoshi Murayama
2005-02-18T23:59:59.000Z
In theories with a low quantum gravity scale, global symmetries are expected to be violated, inducing excessive proton decay or large Majorana neutrino masses. The simplest cure is to impose discrete gauge symmetries, which in turn make neutrinos massless. We construct models that employ these gauge symmetries while naturally generating small neutrino masses. Majorana (Dirac) neutrino masses are generated through the breaking of a discrete (continuous) gauge symmetry at low energies, e.g., 2 keV to 1 GeV. The Majorana case predicts \\Delta N_\
A. Abada; M. Losada
2000-10-12T23:59:59.000Z
We consider a general symmetric $(3\\times 3)$ mass matrix for three generations of neutrinos. Imposing the constraints, from the atmospheric neutrino and solar neutrino anomalies as well as from the CHOOZ experiment, on the mass squared differences and on the mixing angles, we identify the ranges of allowed inputs for the 6 matrix elements. We apply our results to Majorana left-handed neutrino masses generated at tree level and through fermion--sfermion loop diagrams in the MSSM with R-parity violation. The present experimental results on neutrinos from laboratories, cosmology and astrophysics are implemented to either put bounds on trilinear ($\\lambda_{ijk}, \\lambda'_{ijk}$) and bilinear ($\\mu_{e,\\mu,\\tau}$) R-parity-violating couplings or constrain combinations of products of these couplings.
Neutrino Masses: Where Are We? Angelo Nucciotti
· lepton number violation · neutrinoless double beta decay · rare processes (e.g. µ e) · vacuum neutrino
Universal neutrino mass hierarchy and cosmological baryon number asymmetry
Xing Zhizhong [CCAST (World Laboratory), P.O. Box 8730, Beijing 100080 (China); Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918 (4), Beijing 100039 (China)
2004-10-01T23:59:59.000Z
We conjecture that three light Majorana neutrinos and their right-handed counterparts may have a universal geometric mass hierarchy. Incorporating this phenomenological conjecture with the Fritzsch texture of lepton mass matrices in a simple seesaw mechanism, we show that it is possible to simultaneously account for current neutrino oscillation data and the cosmological baryon number asymmetry via leptogenesis.
INTRODUCTION TO THE NEUTRINO PROPERTIES LISTINGS
of neutrino oscillation searches show that the mixing matrix contains two large mixing angles. We cannot is determined and the study of neutrino oscillations provides us with the values of all neutrino mass neutrino oscillation experiments can be consistently described using three active neutrino flavors, i
Transformative A_4 Mixing of Neutrinos with CP Violation
Ernest Ma
2015-04-14T23:59:59.000Z
Given any real $3 \\times 3$ Majorana neutrino mass matrix, the application of a familiar $A_4$ transformation turns it into a well-known form, predicting $\\theta_{23} = \\pi/4$ and $\\delta_{CP} = \\pm \\pi/2$ with $\\theta_{13} \
Wang, Weijian
2013-01-01T23:59:59.000Z
The Majorana neutrino mass textures with a texture zero and a vanishing cofactor are reconsidered in the light of current experimental results. A numerical and systematic analysis is carried out for all viable patterns. In particular, we focus on the phenomenological implication of correlations between three mixing angle (especially for $\\theta_{23}$), Dirac CP-violating phase $\\delta$, the effective Majorana neutrino mass $m_{ee}$. We demonstrated that the correlations between these variables play an important role in the model selection and can be measured in future long-baseline oscillation and neutrinoless double beta decay. Among the six viable patterns, it is the type-III with normal hierarchy and type-VI with inverted hierarchy that have the parameter space where the atmospheric neutrino mixing angle $\\theta_{23}$ is less then maximal and the Dirac CP-violating phase covers its best-fit value.
Weijian Wang; Dong-Jiang Zhang
2013-11-27T23:59:59.000Z
The Majorana neutrino mass textures with a texture zero and a vanishing cofactor are reconsidered in the light of current experimental results. A numerical and systematic analysis is carried out for all viable patterns. In particular, we focus on the phenomenological implication of correlations between three mixing angle (especially for $\\theta_{23}$), Dirac CP-violating phase $\\delta$, the effective Majorana neutrino mass $m_{ee}$. We demonstrated that the correlations between these variables play an important role in the model selection and can be measured in future long-baseline oscillation and neutrinoless double beta decay. Among the six viable patterns, it is the type-III with normal hierarchy and type-VI with inverted hierarchy that have the parameter space where the atmospheric neutrino mixing angle $\\theta_{23}$ is less then maximal and the Dirac CP-violating phase covers its best-fit value.
Neutrino Physics: Fundamentals of Neutrino Oscillations
C. W. Kim
1996-07-22T23:59:59.000Z
In this lecture we review some of the basic properties of neutrinos, in particular their mass and the oscillation behavior. First we discuss how to describe the neutrino mass. Then, under the assumption that neutrinos are massive and mixed, the fundamentals of the neutrino oscillations are discussed with emphasis on subtle aspects which have been overlooked in the past. We then review the terrestrial neutrino oscillation experiments in the framework of three generations of neutrinos with the standard mass hierarchy. Finally, a brief summary of the current status of the solar and atmospheric neutrino problems will be given.
Quasidegeneracy of Majorana Neutrinos and the Origin of Large Leptonic Mixing
G. C. Branco; M. N. Rebelo; J. I. Silva-Marcos; Daniel Wegman
2015-02-20T23:59:59.000Z
We propose that the observed large leptonic mixing may just reflect a quasidegeneracy of three Majorana neutrinos. The limit of exact degeneracy of Majorana neutrinos is not trivial, as leptonic mixing and even CP violation may occur. We conjecture that the smallness of $|U_{13}|$, when compared to the other elements of $U_{PMNS}$, may just reflect the fact that, in the limit of exact mass degeneracy, the leptonic mixing matrix necessarily has a vanishing element. We show that the lifting of the mass degeneracy can lead to the measured value of $|U_{13}|$ while at the same time accommodating the observed solar and atmospheric mixing angles. In the scenario we consider for the breaking of the mass degeneracy there is only one CP violating phase, already present in the limit of exact degeneracy, which upon the lifting of the degeneracy generates both Majorana and Dirac-type CP violation in the leptonic sector. We analyse some of the correlations among physical observables and point out that in most of the cases considered, the implied strength of leptonic Dirac-type CP violation is large enough to be detected in the next round of experiments.
Hybrid method to resolve the neutrino mass hierarchy by supernova (anti)neutrino induced reactions
Vale, D; Paar, N
2015-01-01T23:59:59.000Z
We introduce a hybrid method to determine the neutrino mass hierarchy by simultaneous measurements of responses of at least two detectors to antineutrino and neutrino fluxes from accretion and cooling phases of core-collapse supernovae. The (anti)neutrino-nucleus cross sections for $^{56}$Fe and $^{208}$Pb are calculated in the framework of the relativistic nuclear energy density functional and weak interaction Hamiltonian, while the cross sections for inelastic scattering on free protons $\\mathrm{p}(\\bar{\
Constraining four neutrino mass patterns from neutrinoless double beta decay
Sandip Pakvasa; Probir Roy
2002-04-19T23:59:59.000Z
All existing data on neutrino oscillations (including those from the LSND experiment) imply a four neutrino scheme with six different allowed mass patterns. Some of the latter are shown to be disfavored by using a conservative upper bound on the $\\beta beta 0 \
Physical region for three-neutrino mixing angles
D. C. Latimer; D. J. Ernst
2004-10-11T23:59:59.000Z
We derive a set of symmetry relations for the three-neutrino mixing angles, including the MSW matter effect. Though interesting in their own right, these relations are used to choose the physical region of the mixing angles such that oscillations are parameterized completely and uniquely. We propose that the preferred way of setting the bounds on the mixing angles should be $\\theta_{12} \\in [0,\\pi/2]$, $\\theta_{13} \\in [-\\pi/2,\\pi/2]$, $\\theta_{23}\\in [0,\\pi/2]$, and $\\delta \\in [0,\\pi)$. No CP violation then results simply from setting $\\delta=0$. In the presence of the MSW effect, this choice of bounds is a new result. Since the size of the asymmetry about $\\theta_{13} = 0$ is dependent on the details of the data analysis and is a part of the results of the analysis, we argue that the negative values of $\\theta_{13}$ should not be ignored.
Renormalization of a two-loop neutrino mass model
Babu, K. S. [Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078 (United States); Julio, J. [Fisika LIPI, Kompleks Puspiptek Serpong, Tangerang 15310, Indonesia and Jožef Stefan Institute, Jamova Cesta 39, 1001 Ljubljana (Slovenia)
2014-01-01T23:59:59.000Z
We analyze the renormalization group structure of a radiative neutrino mass model consisting of a singly charged and a doubly charged scalar fields. Small Majorana neutrino masses are generated by the exchange of these scalars via two-loop diagrams. We derive boundedness conditions for the Higgs potential and show how they can be satisfied to energies up to the Planck scale. Combining boundedness and perturbativity constraints with neutrino oscillation phenomenology, new limits on the masses and couplings of the charged scalars are derived. These in turn lead to lower limits on the branching ratios for certain lepton flavor violating (LFV) processes such as ??e?, ??3e and ? – e conversion in nuclei. Improved LFV measurements could test the model, especially in the case of inverted neutrino mass hierarchy where these are more prominent.
Constraints on neutrino masses from future cosmological observations
Hirano, Koichi [Department of Elementary Education, Tsuru University, Tsuru 402-8555 (Japan)
2014-05-02T23:59:59.000Z
Constraints on neutrino masses are estimated based on future observations of the cosmic microwave background (CMB) including the B-mode polarization produced by CMB lensing using the Planck satellite, and baryon acoustic oscillations distance scale and the galaxy power spectrum from all-sky galaxy redshift survey in the BigBOSS experiment. We estimate the error in the bound on the total neutrino mass to be ??m{sub v} = 0.012 eV with a 68% confidence level. If the fiducial value of the total neutrino mass is ?m{sub v} = 0.06 eV, this result implies that the neutrino mass hierarchy must be normal.
Srubabati Goswami; Werner Rodejohann
2007-10-08T23:59:59.000Z
The MiniBooNE and LSND experiments are compatible with each other when two sterile neutrinos are added to the three active ones. In this case there are eight possible mass orderings. In two of them both sterile neutrinos are heavier than the three active ones. In the next two scenarios both sterile neutrinos are lighter than the three active ones. The remaining four scenarios have one sterile neutrino heavier and another lighter than the three active ones. We analyze all scenarios with respect to their predictions for mass-related observables. These are the sum of neutrino masses as constrained by cosmological observations, the kinematic mass parameter as measurable in the KATRIN experiment, and the effective mass governing neutrinoless double beta decay. It is investigated how these non-oscillation probes can distinguish between the eight scenarios. Six of the eight possible mass orderings predict positive signals in the KATRIN and future neutrinoless double beta decay experiments. We also remark on scenarios with three sterile neutrinos. In addition we make some comments on the possibility of using decays of high energy astrophysical neutrinos to discriminate between the mass orderings in presence of two sterile neutrinos.
KATRIN: an experiment to measure the neutrino mass
R. G. H. Robertson; for the KATRIN Collaboration
2007-12-23T23:59:59.000Z
KATRIN is a very large scale tritium-beta-decay experiment to determine the mass of the neutrino. It is presently under construction at the Forschungszentrum Karlsruhe, and makes use of the Tritium Laboratory built there for the ITER project. The combination of a very large retarding-potential electrostatic-magnetic spectrometer and an intense gaseous molecular tritium source makes possible a sensitivity to neutrino mass of 0.2 eV, about an order of magnitude below present laboratory limits. The measurement is kinematic and independent of whether the neutrino is Dirac or Majorana. The status of the project is summarized briefly in this report.
Mass Spectrum and Number of Light Neutrinos: An Attempt of the Gauge Explanation
Dyatlov, I T
2009-01-01T23:59:59.000Z
Symplectic flavour symmetry group Sp(n/2) (n is even) of n Majorana states does not allow for invariant Majorana masses. Only specific mass matrices with diagonal and nondiagonal elements are possible here. As a result of the spontaneous violation of flavour and chiral symmetries, a mass matrix could appear only for the number of flavours n = 6 and only together with R,L-symmetry violation (i.e., parity violation). The see-saw mechanism produces here three light and three heavy Dirac particles (neutrinos). The peculiarity of the observed light neutrino spectrum: two states located far from the third one, can be explained by certain simple properties of mass matrices appearing in Sp(3). The ordering of the states corresponds to normal mass hierarchy. Situation, when neutrino mass differences are significantly less than masses themselves, appears to be unrealizable here. Mixing angles for neutrinos can not be determined without understanding formation mechanisms for charged lepton spectrum and Majorana state we...
Mass Spectrum and Number of Light Neutrinos: An Attempt of the Gauge Explanation
I. T. Dyatlov
2009-10-01T23:59:59.000Z
Symplectic flavour symmetry group Sp(n/2) (n is even) of n Majorana states does not allow for invariant Majorana masses. Only specific mass matrices with diagonal and nondiagonal elements are possible here. As a result of the spontaneous violation of flavour and chiral symmetries, a mass matrix could appear only for the number of flavours n = 6 and only together with R,L-symmetry violation (i.e., parity violation). The see-saw mechanism produces here three light and three heavy Dirac particles (neutrinos). The peculiarity of the observed light neutrino spectrum: two states located far from the third one, can be explained by certain simple properties of mass matrices appearing in Sp(3). The ordering of the states corresponds to normal mass hierarchy. Situation, when neutrino mass differences are significantly less than masses themselves, appears to be unrealizable here. Mixing angles for neutrinos can not be determined without understanding formation mechanisms for charged lepton spectrum and Majorana state weak currents.
Neutrino Mass Matrices with $M_{ee} = 0$
BenTov, Yoni
2011-01-01T23:59:59.000Z
Motivated by the possibility that the amplitude for neutrinoless double beta decay may be much smaller than the planned sensitivity of future experiments, we study ansatze for the neutrino mass matrix with $M_{ee} = 0$. For the case in which CP is conserved, we consider two classes of real-valued mass matrices: "Class I" defined by $|M_{e\\mu}| = |M_{e\\tau}|$, and "Class II" defined by $|M_{\\mu\\mu}| = |M_{\\tau\\tau}|$. The important phenomenological distinction between the two is that Class I permits only "small" values of $V_{e3}$ up to $\\sim 0.03$, while Class II admits "large" values of $V_{e3}$ up to its empirical upper limit of 0.22. Then we introduce CP-violating complex phases into the mass matrix. We show that it is possible to have tribimaximal mixing with $M_{ee} = 0$ and $|M_{\\mu\\tau}| = |M_{\\mu\\mu}| = |M_{\\tau\\tau}|$ if the Majorana phase angles are $\\pm\\pi/4$. Alternatively, for smaller values of $|M_{\\mu\\tau}| = |M_{\\mu\\mu}| = |M_{\\tau\\tau}|$ it is possible to obtain $|V_{e3}| \\sim 0.2$ and genera...
Particle physics implications of the WMAP neutrino mass bound
G. Bhattacharyya; H. Päs; L. Song; T. J. Weiler
2003-04-25T23:59:59.000Z
The recently published cosmological bound on the absolute neutrino masses obtained from the Wilkinson Microwave Anisotropy Probe (WMAP) data has important consequences for neutrino experiments and models. Taken at face value, the new bound excludes the determination of the absolute neutrino mass in the KATRIN experiment and disfavors a neutrino oscillation interpretation of the LSND experiment. Combined with the KamLAND and Super-K data, the WMAP bound defines an accessible range for the neutrinoless double beta decay amplitude. The bound also impacts the Z-burst annihilation mechanism for resonant generation of extreme-energy cosmic rays on the cosmic neutrino background in two ways: it constrains the local overdensity of neutrino dark matter which is not helpful, but it also limits the resonant energy to a favorable range. In R-parity violating SUSY models neutrino masses are generated by trilinear and bilinear lepton number violating couplings. The WMAP result improves the constraints on these couplings over their existing values by an order of magnitude.
Damanik, Asan
2010-01-01T23:59:59.000Z
Neutrino mass matrix via a seesaw mechanism is constructed by assuming that the underlying symmetry of both heavy Majorana and Dirac mass matrices is the discrete subgroup $\\Delta(27)$ symmetry of $SU(3)$. Using the experimental data of neutrino oscillation, the neutrino mass matrix exhibits maximal $\
Some comments on high precision study of neutrino oscillations
Bilenky, S M
2015-01-01T23:59:59.000Z
I discuss some problems connected with the high precision study of neutrino oscillations. In the general case of $n$-neutrino mixing I derive a convenient expression for transition probability in which only independent terms (and mass-squared differences) enter. For three-neutrino mixing I discuss a problem of a definition of a large (atmospheric) neutrino mass-squared difference. I comment also possibilities to reveal the character of neutrino mass spectrum in future reactor neutrino experiments.
Albright, Carl H.; Barr, S. M.
2001-10-01T23:59:59.000Z
An SO(10) supersymmetric grand unified model proposed earlier leading to the solar solution involving ''just-so'' vacuum oscillations is reexamined to study its ability to obtain the other possible solar solutions. It is found that all four viable solar neutrino oscillation solutions can be achieved in the model simply by modification of the right-handed Majorana neutrino mass matrix M{sub R}. Whereas the small mixing and vacuum solutions are easily obtained with several texture zeros in M{sub R}, the currently favored large mixing angle solution requires a nearly geometric hierarchical form for M{sub R} that leads by the seesaw formula to a light neutrino mass matrix which has two or three texture zeros. The form of the matrix which provides the ''fine-tuning'' necessary to achieve the large mixing angle solution can be understood in terms of Froggatt-Nielsen diagrams for the Dirac and right-handed Majorana neutrino mass matrices. The solution satisfies several leptogenesis requirements which in turn can be responsible for the baryon asymmetry in the universe.
Neutrino mass matrices with M{sub ee}=0
BenTov, Yoni [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Zee, A. [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States)
2011-10-01T23:59:59.000Z
Motivated by the possibility that the amplitude for neutrinoless double beta decay may be much smaller than the planned sensitivity of future experiments, we study Ansaetze for the neutrino mass matrix with M{sub ee}=0. For the case in which CP is conserved, we consider two classes of real-valued mass matrices: ''Class I'' defined by |M{sub e{mu}|}=|M{sub e{tau}|}, and ''Class II'' defined by |M{sub {mu}{mu}|}=|M{sub {tau}{tau}|}. The important phenomenological distinction between the two is that Class I permits only small values of V{sub e3} up to {approx}0.03, while Class II admits large values of V{sub e3} up to its empirical upper limit of 0.22. Then we introduce CP-violating complex phases into the mass matrix. We show that it is possible to have tribimaximal mixing with M{sub ee}=0 and |M{sub {mu}{tau}|}=|M{sub {mu}{mu}|}=|M{sub {tau}{tau}|} if the Majorana phase angles are {+-}{pi}/4. Alternatively, for smaller values of |M{sub {mu}{tau}|}=|M{sub {mu}{mu}|}=|M{sub {tau}{tau}|} it is possible to obtain |V{sub e3}|{approx}0.2 and generate relatively large CP-violating amplitudes. To eliminate phase redundancy, we emphasize rephasing any mass matrix with M{sub ee}=0 into a standard form with two complex phases. The discussion alternates between analytical and numerical but remains purely phenomenological, without any attempt to derive mass matrices from a fundamental theory.
The double mass hierarchy pattern: simultaneously understanding quark and lepton mixing
Wolfgang Gregor Hollik; Ulises Jesus Saldana Salazar
2015-01-21T23:59:59.000Z
The charged fermion masses of the three generations exhibit the two strong hierarchies m_3 >> m_2 >> m_1. We assume that also neutrino masses satisfy m_{nu 3} > m_{nu 2} > m_{nu 1} and derive the consequences of the hierarchical spectra on the fermionic mixing patterns. The quark and lepton mixing matrices are built in a general framework with their matrix elements expressed in terms of the four fermion mass ratios m_u/m_c, m_c/m_t, m_d/m_s, and m_s/m_b and m_e/m_mu, m_mu/m_tau, m_{nu 1}/m_{nu 2}, and m_{nu 2}/m_{nu 3}, for the quark and lepton sector, respectively. In this framework, we show that the resulting mixing matrices are consistent with data for both quarks and leptons, despite the large leptonic mixing angles. The minimal assumption we take is the one of hierarchical masses and minimal flavour symmetry breaking that strongly follows from phenomenology. No special structure of the mass matrices has to be assumed that cannot be motivated by this minimal assumption. This analysis allows us to predict the neutrino mass spectrum and set the mass of the lightest neutrino well below 0.01 eV. The method also gives the 1 sigma allowed ranges for the leptonic mixing matrix elements. Contrary to the common expectation, leptonic mixing angles are found to be determined solely by the four leptonic mass ratios without any relation to symmetry considerations as commonly used in flavor model building. Still, our formulae can be used to build up a flavor model that predicts the observed hierarchies in the masses---the mixing follows then from the procedure which is developed in this work.
Probing the Neutrino Mass Hierarchy with Super-Kamiokande
Agarwalla, Sanjib Kumar
2012-01-01T23:59:59.000Z
We show that a superbeam with an average neutrino energy of ~ 5 GeV, such as those being proposed at CERN, if pointing to Super-Kamiokande (L \\simeq 8770 km), could reveal the neutrino mass hierarchy at 5 sigma in less than two years irrespective of the true hierarchy and CP phase. The measurement relies on the near resonant matter effect in the numu \\rightarrow nue oscillation channel, and can be done counting the total number of appearance events with just a neutrino beam.
Loop-induced Neutrino Masses: A Case Study
Geng, Chao-Qiang; Tsai, Lu-Hsing
2014-01-01T23:59:59.000Z
We study the cocktail model in which the Majorana neutrino masses are generated by the so-called "cocktail" three-loop diagrams with the dark matter particle running in the loops. In particular, we give the correct analytic expressions of the neutrino masses in the model by the detailed calculation of the cocktail diagrams. Based on the reliable numerical calculation of the loop integrals, we explore the parameter space which can give the correct orders of neutrino masses while satisfying other experimental constraints, such as those from the neutrinoless double beta decay, low-energy lepton flavor violation processes, electroweak precision tests, and collider searches. As a result, the large couplings and the large mass difference between the two singly-charged (neutral) scalars are required.
Neutrinoless double beta decay and neutrino physics
Werner Rodejohann
2012-08-20T23:59:59.000Z
The connection of neutrino physics with neutrinoless double beta decay is reviewed. After presenting the current status of the PMNS matrix and the theoretical background of neutrino mass and lepton mixing, we will summarize the various implications of neutrino physics for double beta decay. The influence of light sterile neutrinos and other exotic modifications of the three neutrino picture is also discussed.
Majorana Neutrino Masses Can Save One Family Technicolour
NJ Evans; DA Ross
1993-07-05T23:59:59.000Z
We make non perturbative estimates of the electroweak radiative correction parameter $S$ in dynamical symmetry breaking models with Majorana neutrino masses. The Majorana masses are treated as perturbations to a Non Local Chiral Model of the strong interactions. We argue that parameter ranges exist that would allow realistic values of $S$ and $T$ in one family Technicolour models.
Decay Oscillations in Electron Capture and the Neutrino Mass Difference
Murray Peshkin
2014-03-17T23:59:59.000Z
Quantum mechanical theory disallows the model that has been used to infer the neutrino mass difference from the reported "GSI oscillations" in the rates of decay of hydrogen-like ions by electron capture. It has not been proved that the existence of mass-difference-dependent oscillations conflicts with quantum mechanics but no consistent quantum mechanical model has been shown to predict them.
Large neutrino asymmetries from neutrino oscillations
R. Foot; M. J. Thomson; R. R. Volkas
1995-09-19T23:59:59.000Z
We re-examine neutrino oscillations in the early universe. Contrary to previous studies, we show that large neutrino asymmetries can arise due to oscillations between ordinary neutrinos and sterile neutrinos. This means that the Big Bang Nucleosynthesis (BBN) bounds on the mass and mixing of ordinary neutrinos with sterile neutrinos can be evaded. Also, it is possible that the neutrino asymmetries can be large (i.e. $\\stackrel{>}{\\sim} 10\\%$), and hence have a significant effect on BBN through nuclear reaction rates.
Renormalisation Group Corrections to Neutrino Mass Sum Rules
Gehrlein, Julia; Spinrath, Martin
2015-01-01T23:59:59.000Z
Neutrino mass sum rules are an important class of predictions in flavour models relating the Majorana phases to the neutrino masses. This leads, for instance, to enormous restrictions on the effective mass as probed in experiments on neutrinoless double beta decay. While up to now these sum rules have in practically all cases been taken to hold exactly, we will go here beyond that. After a discussion of the types of corrections that could possibly appear and elucidating on the theory behind neutrino mass sum rules, we estimate and explicitly compute the impact of radiative corrections, as these appear in general and thus hold for whole groups of models. We discuss all neutrino mass sum rules currently present in the literature, which together have realisations in more than 50 explicit neutrino flavour models. We find that, while the effect of the renormalisation group running can be visible, the qualitative features do not change. This finding strongly backs up the solidity of the predictions derived in the l...
Nearly degenerate heavy sterile neutrinos in cascade decay: mixing and oscillations
Boyanovsky, Daniel
2014-01-01T23:59:59.000Z
Some extensions beyond the Standard Model propose the existence of nearly degenerate heavy sterile neutrinos. If kinematically allowed these can be resonantly produced and decay in a cascade to common final states. The common decay channels lead to mixing of the heavy sterile neutrino states and interference effects. We implement non-perturbative methods to study the dynamics of the cascade decay to common final states, which features similarities but also noteworthy differences with the case of neutral meson mixing. We show that mixing and oscillations among the nearly degenerate sterile neutrinos can be detected as \\emph{quantum beats} in the distribution of final states produced from their decay. These oscillations would be a telltale signal of mixing between heavy sterile neutrinos. We study in detail the case of two nearly degenerate sterile neutrinos produced in the decay of pseudoscalar mesons and decaying into a purely leptonic "visible" channel: $\
Nearly degenerate heavy sterile neutrinos in cascade decay: mixing and oscillations
Daniel Boyanovsky
2014-11-20T23:59:59.000Z
Some extensions beyond the Standard Model propose the existence of nearly degenerate heavy sterile neutrinos. If kinematically allowed these can be resonantly produced and decay in a cascade to common final states. The common decay channels lead to mixing of the heavy sterile neutrino states and interference effects. We implement non-perturbative methods to study the dynamics of the cascade decay to common final states, which features similarities but also noteworthy differences with the case of neutral meson mixing. We show that mixing and oscillations among the nearly degenerate sterile neutrinos can be detected as \\emph{quantum beats} in the distribution of final states produced from their decay. These oscillations would be a telltale signal of mixing between heavy sterile neutrinos. We study in detail the case of two nearly degenerate sterile neutrinos produced in the decay of pseudoscalar mesons and decaying into a purely leptonic "visible" channel: $\
Tribimaximal neutrino mixing and neutrinoless double beta decay
Hirsch, M.; Morisi, S.; Valle, J. W. F. [AHEP Group, Institut de Fisica Corpuscular-- C.S.I.C./Universitat de Valencia, Edificio Institutos de Paterna, Apt 22085, E-46071 Valencia (Spain)
2008-11-01T23:59:59.000Z
We present a tribimaximal lepton mixing scheme where the neutrinoless double beta decay rate has a lower bound which correlates with the ratio {alpha}{identical_to}{delta}m{sub sol}{sup 2}/{delta}m{sub atm}{sup 2} well determined by current data, as well as with the unknown Majorana CP phase {phi}{sub 12} characterizing the solar neutrino subsystem. For the special value {phi}{sub 12}=({pi}/2) (opposite CP-sign neutrinos) the {beta}{beta}{sub 0{nu}} rate vanishes at tree level when {delta}m{sub sol}{sup 2}/{delta}m{sub atm}{sup 2}=3/80, only allowed at 3{sigma}. For all other cases the rate is nonzero, and lies within current and projected experimental sensitivities close to {phi}{sub 12}=0. We suggest two model realizations of this scheme in terms of A{sub 4}xZ{sub 2} and A{sub 4}xZ{sub 4} flavor symmetries.
Neutrinoless double {beta}-decay and neutrino mass hierarchies
Bilenky, S. M. [Scuola Internazionale Superiore di Studi Avanzati, I-34014 Trieste (Italy); Faessler, Amand; Gutsche, Thomas; Simkovic, Fedor [Institute fuer Theoretische Physik der Universitaet Tuebingen, D-72076 Tuebingen (Germany)
2005-09-01T23:59:59.000Z
In the framework of the seesaw mechanism the normal hierarchy is favorable for the neutrino mass spectrum. For this spectrum we present a detailed calculation of the half-lives of neutrinoless double {beta}-decay for several nuclei of experimental interest. The half-lives are evaluated by considering the most comprehensive nuclear matrix elements, which were obtained within the renormalized quasiparticle random phase approximation by the Bratislava-Caltech-Tuebingen group. The dependence of the half-lives on sin{sup 2}{theta}{sub 13} and the lightest neutrino mass is studied. We present also the results of the calculations of the half-lives of neutrinoless double {beta}-decay in the case of the inverted hierarchy of neutrino masses.
Neutrino oscillation studies with reactors
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Vogel, P. [California Inst. of Technology (CalTech), Pasadena, CA (United States). Kellog Radiation Lab.; Wen, L.J. [Chinese Academy of Sciences (CAS), Beijing (China). Inst. of High Energy Physics (IHEP); Zhang, C. [Brookhaven National Lab. (BNL), Upton, NY (United States)
2015-04-27T23:59:59.000Z
Nuclear reactors are one of the most intense, pure, controllable, cost-effective and well-understood sources of neutrinos. Reactors have played a major role in the study of neutrino oscillations, a phenomenon that indicates that neutrinos have mass and that neutrino flavours are quantum mechanical mixtures. Over the past several decades, reactors were used in the discovery of neutrinos, were crucial in solving the solar neutrino puzzle, and allowed the determination of the smallest mixing angle ?13. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos.
Neutrino Oscillation Studies with Reactors
Petr Vogel; Liangjian Wen; Chao Zhang
2015-04-27T23:59:59.000Z
Nuclear reactors are one of the most intense, pure, controllable, cost-effective, and well-understood sources of neutrinos. Reactors have played a major role in the study of neutrino oscillations, a phenomenon that indicates that neutrinos have mass and that neutrino flavors are quantum mechanical mixtures. Over the past several decades reactors were used in the discovery of neutrinos, were crucial in solving the solar neutrino puzzle, and allowed the determination of the smallest mixing angle $\\theta_{13}$. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos.
Neutrino Oscillation Studies with Reactors
Vogel, Petr; Zhang, Chao
2015-01-01T23:59:59.000Z
Nuclear reactors are one of the most intense, pure, controllable, cost-effective, and well-understood sources of neutrinos. Reactors have played a major role in the study of neutrino oscillations, a phenomenon that indicates that neutrinos have mass and that neutrino flavors are quantum mechanical mixtures. Over the past several decades reactors were used in the discovery of neutrinos, were crucial in solving the solar neutrino puzzle, and allowed the determination of the smallest mixing angle $\\theta_{13}$. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos.
Constraining bilinear R-parity violation from neutrino masses
Gozdz, Marek; Kaminski, Wieslaw A. [Department of Informatics, Maria Curie-Sklodowska University pl. Marii Curie-Sklodowskiej 5, 20-031 Lublin (Poland)
2008-10-01T23:59:59.000Z
We confront the R-parity violating minimal supersymmetric standard model with the neutrino oscillation data. Investigating the 1-loop particle-sparticle diagrams with additional bilinear insertions on the external neutrino lines we construct the relevant contributions to the neutrino mass matrix. A comparison of the so-obtained matrices with the experimental ones assuming normal or inverted hierarchy and taking into account possible CP-violating phases allows to set constraints on the values of the bilinear coupling constants. A similar calculation is presented with the input from the Heidelberg-Moscow neutrinoless double beta decay experiment. We base our analysis on the renormalization group evolution of the minimal supersymmetric standard model parameters which are unified at the grand unified theory scale. Using the obtained bounds we calculate the contributions to the Majorana neutrino transition magnetic moments.
KETTELL, S.; ET AL.
2006-10-16T23:59:59.000Z
This document describes the design of the Daya Bay reactor neutrino experiment. Recent discoveries in neutrino physics have shown that the Standard Model of particle physics is incomplete. The observation of neutrino oscillations has unequivocally demonstrated that the masses of neutrinos are nonzero. The smallness of the neutrino masses (<2 eV) and the two surprisingly large mixing angles measured have thus far provided important clues and constraints to extensions of the Standard Model. The third mixing angle, {delta}{sub 13}, is small and has not yet been determined; the current experimental bound is sin{sup 2} 2{theta}{sub 13} < 0.17 at 90% confidence level (from Chooz) for {Delta}m{sub 31}{sup 2} = 2.5 x 10{sup -3} eV{sup 2}. It is important to measure this angle to provide further insight on how to extend the Standard Model. A precision measurement of sin{sup 2} 2{theta}{sub 13} using nuclear reactors has been recommended by the 2004 APS Multi-divisional Study on the Future of Neutrino Physics as well as a recent Neutrino Scientific Assessment Group (NUSAG) report. We propose to perform a precision measurement of this mixing angle by searching for the disappearance of electron antineutrinos from the nuclear reactor complex in Daya Bay, China. A reactor-based determination of sin{sup 2} 2{theta}{sub 13} will be vital in resolving the neutrino-mass hierarchy and future measurements of CP violation in the lepton sector because this technique cleanly separates {theta}{sub 13} from CP violation and effects of neutrino propagation in the earth. A reactor-based determination of sin{sup 2} 2{theta}{sub 13} will provide important, complementary information to that from long-baseline, accelerator-based experiments. The goal of the Daya Bay experiment is to reach a sensitivity of 0.01 or better in sin{sup 2} 2{theta}{sub 13} at 90% confidence level.
Verifiable radiative seesaw mechanism of neutrino mass and dark matter
Ma, Ernest [Physics Department, University of California, Riverside, California 92521 (United States)
2006-04-01T23:59:59.000Z
Neutrino oscillations have established that neutrinos {nu}{sub i} have very small masses. Theoretically, they are believed to arise through the famous seesaw mechanism from their very heavy and unobservable Dirac mass partners N{sub i}. It is proposed here in a new minimal extension of the standard model with a second scalar doublet ({eta}{sup +}, {eta}{sup 0}) that the seesaw mechanism is actually radiative, and that N{sub i} and ({eta}{sup +}, {eta}{sup 0}) are experimentally observable at the forthcoming Large Hadron Collider, with the bonus that the lightest of them is also an excellent candidate for the dark matter of the Universe.
Neutrino-Driven Mass Loading of GRMHD Outflows
Amir Levinson
2006-10-15T23:59:59.000Z
A GRMHD model of disk outflows with neutrino-driven mass ejection is presented. The model is used to calculate the structure of the outflow in the sub-slow magnetosonic region and the mass loading of the outflow, under conditions anticipated in the central engines of gamma-ray bursts. It is concluded that magnetic launching of ultra-relativistic polar outflows is in principle possible along low inclination field lines (with respect to the symmetry axis), provided the neutrino luminosity is sufficiently low, $L_\
Neutrino masses and the number of neutrino species from WMAP and 2dFGRS
Steen Hannestad
2003-03-04T23:59:59.000Z
We have performed a thorough analysis of the constraints which can be put on neutrino parameters from cosmological observations, most notably those from the WMAP satellite and the 2dF galaxy survey. For this data we find an upper limit on the sum of active neutrino mass eigenstates of \\sum m_nu < 1.0 eV (95% conf.), but this limit is dependent on priors. We find that the WMAP and 2dF data alone cannot rule out the evidence from neutrinoless double beta decay reported by the Heidelberg-Moscow experiment. In terms of the relativistic energy density in neutrinos or other weakly interacting species we find, in units of the equivalent number of neutrino species, N_nu, that N_nu = 4.0+3.0-2.1 (95% conf.). When BBN constraints are added, the bound on N_\
Search for sterile neutrino mixing in the MINOS long baseline experiment
Adamson, P.; /Fermilab; Andreopoulos, C.; /Rutherford; Auty, D.J.; /Sussex U.; Ayres, D.S.; /Argonne; Backhouse, C.; /Oxford U.; Barnes Jr., P.D.; /LLNL, Livermore; Barr, G.; /Oxford U.; Barrett, W.L.; /Western Washington U.; Bishai, M.; /Brookhaven; Blake, A.; /Cambridge U.; Bock, G.J.; /Fermilab /Fermilab
2010-01-01T23:59:59.000Z
A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18 x 10{sup 20} protons on target in which neutrinos of energies between {approx}500 MeV and 120 GeV are produced predominantly as {nu}{sub {mu}}, the visible energy spectrum of candidate neutral-current reactions in the MINOS far-detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the {nu}{sub {mu}} flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles {theta}{sub 24} and {theta}{sub 34} are constrained to be less than 11{sup o} and 56{sup o} at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime {tau}{sub 3}/m{sub 3} > 2.1 x 10{sup -12} s/eV at 90% C.L.
Guesswork for Dirac and Majorana neutrino mass matrices
W. Krolikowski
2004-01-14T23:59:59.000Z
In the framework of seesaw mechanism with three neutrino flavors, we propose tentatively an efficient parametrization for the spectra of Dirac and righthanded Majorana neutrino mass matrices in terms of three free parameters. Two of them are related to (and determined by) the corresponding parameters introduced previously for the mass spectra of charged leptons and up and down quarks. The third is determined from the experimental estimate of solar $\\Delta m^2_{21}$. Then, the atmospheric $\\Delta m^2_{32}$ is {\\it predicted} close to its experimental estimation. With the use of these three parameters all light active-neutrino masses $ m_1 < m_2 < m_3$ and heavy sterile-neutrino masses $ M_1 < M_2 < M_3$ are readily evaluated. The latter turn out much more {\\it hierarchical} than the former. The lightest heavy mass $ M_1$ comes out to be of the order $O(10^6 {\\rm GeV})$ so, it is too light to imply that the mechanism of baryogenesis through thermal leptogenesis might work.
Volume 159B, number 1 PHYSICS LETTERS 12 September 1985 NEUTRINO MASSES AND FAMILY SYMMETRY *
Preskill, John
on the measurement of the electron neutrino mass and on the search for neutrinoless double beta decay (#12
Cao Qinghong [Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); High Energy Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, U.S.A (United States); Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637 (United States); Khalil, Shaaban [Centre for Theoretical Physics, The British University in Egypt, El Sherouk City, Postal No. 11837, P.O. Box 43 (Egypt); Department of Mathematics, Ain Shams University, Faculty of Science, Cairo 11566 (Egypt); Ma, Ernest [Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States); Okada, Hiroshi [School of Physics, KIAS, Seoul 130-722 (Korea, Republic of)
2011-10-01T23:59:59.000Z
We discuss how {theta}{sub 13}{ne}0 is accommodated in a recently proposed renormalizable model of neutrino mixing using the non-Abelian discrete symmetry T{sub 7} in the context of a supersymmetric extension of the standard model with gauged U(1){sub B-L}. We predict a correlation between {theta}{sub 13} and {theta}{sub 23}, as well as the effective neutrino mass m{sub ee} in neutrinoless double beta decay.
Neutrino Mass, Sneutrino Dark Matter and Signals of Lepton Flavor Violation in the MRSSM
Kumar, Abhishek; Weiner, Neal
2009-01-01T23:59:59.000Z
We study the phenomenology of mixed-sneutrino dark matter in the Minimal R-Symmetric Supersymmetric Standard Model (MRSSM). Mixed sneutrinos fit naturally within the MRSSM, as the smallness (or absence) of neutrino Yukawa couplings singles out sneutrino A-terms as the only ones not automatically forbidden by R-symmetry. We perform a study of randomly generated sneutrino mass matrices and find that (i) the measured value of $\\Omega_{DM}$ is well within the range of typical values obtained for the relic abundance of the lightest sneutrino, (ii) with small lepton-number-violating mass terms $m_{nn}^{2} {\\tilde n} {\\tilde n}$ for the right-handed sneutrinos, random matrices satisfying the $\\Omega_{DM}$ constraint have a decent probability of satisfying direct detection constraints, and much of the remaining parameter space will be probed by upcoming experiments, (iii) the $m_{nn}^{2} {\\tilde n} {\\tilde n}$ terms radiatively generate appropriately small Majorana neutrino masses, with neutrino oscillation data favo...
False Vacuum in the Supersymmetric Mass Varying Neutrino Model
Tanimoto, Morimitsu [Department of Physics, Niigata University, Niigata 950-2181 (Japan)
2009-04-17T23:59:59.000Z
We discuss the vacuum structure of the scalar potential in a supersymmetric Mass Varying Neutrinos model. The observed dark energy density is identified with the false vacuum energy and the dark energy scale of order (10{sup -3} eV){sup 4} is understood by gravitationally suppressed supersymmetry breaking scale, F(TeV{sup 2})/M{sub pl}.
Recipes and Ingredients for Neutrino Mass at Loop Level
Yasaman Farzan; Silvia Pascoli; Michael A. Schmidt
2013-03-25T23:59:59.000Z
The large hierarchy between the neutrino mass scale and that of the other fermions seems to be unnatural from a theoretical point of view. Various strategies have been devised in order to generate naturally small values of neutrino masses. One of these techniques is neutrino mass generation at the loop level which requires a mechanism, e.g., a symmetry, to forbid the lower order contributions. Here, we study in detail the conditions on this type of symmetries. We put special emphasis on the discrete Z_n symmetries as a simple example but our results can be also extended to more general groups. We find that regardless of the details of the symmetry, in certain cases the existence of a lower order contribution to neutrino masses can be determined by the topology of the diagrams with a given number of loops. We discuss the lepton flavor violating rare decays as well as (g-2)_\\mu in this class of models, which generically appear at the one loop level. Typically the imposed symmetry has important implications for dark matter, with the possibility of stabilizing one or even multiple dark matter candidates.
Improved measurements of the neutrino mixing angle ?[subscript 13] with the Double Chooz detector
Conrad, Janet
The Double Chooz experiment presents improved measurements of the neutrino mixing angle ?[subscript 13] using the data collected in 467.90 live days from a detector positioned at an average distance of 1050 m from two ...
Non standard neutrino interactions
Miranda, O G
2015-01-01T23:59:59.000Z
Neutrino oscillations have become well-known phenomenon; the measurements of neutrino mixing angles and mass squared differences are continuously improving. Future oscillation experiments will eventually determine the remaining unknown neutrino parameters, namely, the mass ordering, normal or inverted, and the CP-violating phase. On the other hand, the absolute mass scale of neutrinos could be probed by cosmological observations, single beta decay as well as by neutrinoless double beta decay experiments. Furthermore, the last one may shed light on the nature of neutrinos, Dirac or Majorana, by measuring the effective Majorana mass of neutrinos. However, the neutrino mass generation mechanism remains unknown. A well-motivated phenomenological approach to search for new physics, in the neutrino sector, is that of non-standard interactions. In this short review, the current constraints in this picture, as well as the perspectives from future experiments, are discussed.
False vacuum in the supersymmetric mass varying neutrinos model
Takahashi, Ryo; Tanimoto, Morimitsu [Graduate School of Science and Technology, Niigata University, 950-2181 Niigata (Japan); Department of Physics, Niigata University, 950-2181 Niigata (Japan)
2008-02-15T23:59:59.000Z
We present detailed analyses of the vacuum structure of the scalar potential in a supersymmetric mass varying neutrinos model. The observed dark energy density is identified with false vacuum energy and the dark energy scale of order (10{sup -3} eV){sup 4} is understood by the gravitationally suppressed supersymmetry breaking scale, F(TeV){sup 2}/M{sub Pl}, in the model. The vacuum expectation values of sneutrinos should be tiny in order that the model works. Some decay processes of superparticles into an acceleron and sterile neutrino are also discussed in the model.
False Vacuum in the Supersymmetric Mass Varying Neutrinos Model
Ryo Takahashi; Morimitsu Tanimoto
2007-11-04T23:59:59.000Z
We present detailed analyses of the vacuum structure of the scalar potential in a supersymmetric Mass Varying Neutrinos model. The observed dark energy density is identified with false vacuum energy and the dark energy scale of order $(10^{-3}eV)^4$ is understood by gravitationally suppressed supersymmetry breaking scale, $F({TeV})^2/M_{Pl}$, in the model. The vacuum expectation values of sneutrinos should be tiny in order that the model works. Some decay processes of superparticles into acceleron and sterile neutrino are also discussed in the model.
Textures with two traceless submatrices of the neutrino mass matrix
H. A. Alhendi; E. I. Lashin; A. A. Mudlej
2008-02-27T23:59:59.000Z
We propose a new texture for the light neutrino mass matrix. The proposal is based upon imposing zero-trace condition on the two by two sub-matrices of the complex symmetric Majorana mass matrix in the flavor basis where the charged lepton mass matrix is diagonal. Restricting the mass matrix to have two traceless sub-matrices may be found sufficient to describe the current data. Eight out of fifteen independent possible cases are found to be compatible with current data. Numerical and some approximate analytical results are presented.
Study of Two-Loop Neutrino Mass Generation Models
Geng, Chao-Qiang
2015-01-01T23:59:59.000Z
We study the models with the Majorana neutrino masses generated radiatively by two-loop diagrams due to the Yukawa $\\rho \\bar \\ell_R^c \\ell_R$ and effective $\\rho^{\\pm\\pm} W^\\mp W^\\mp$ couplings along with a scalar triplet $\\Delta$, where $\\rho$ is a doubly charged singlet scalar, $\\ell_R$ the charged lepton and $W$ the charged gauge boson. A generic feature in these types of models is that the neutrino mass spectrum has to be a normal hierarchy. Furthermore, by using the neutrino oscillation data and comparing with the global fitting result in the literature, we find a unique neutrino mass matrix and predict the Dirac and two Majorana CP phases to be $1.40\\pi$, $1.11\\pi$ and $1.47\\pi$, respectively. We also discuss the model parameters constrained by the lepton flavor violating processes and electroweak oblique parameters. In addition, we show that the rate of the neutrinoless double beta decay $(0\
Forbidden unique beta-decays and neutrino mass
Dvornický, Rastislav [Bogoliubov Laboratory of Theoretical Physics, JINR Dubna, 141980 Dubna, Moscow region, Russian Federation and Department of Nuclear Physics and Biophysics, Comenius University, Mlynská dolina F1, SK-84215 Bratislava (Slovakia); Šimkovic, Fedor [Department of Nuclear Physics and Biophysics, Comenius University, Mlynská dolina F1, SK-84215 Bratislava, Slovakia and IEAP, Czech Technical University, CZ-128 00 Prague (Czech Republic)
2013-12-30T23:59:59.000Z
The measurement of the electron spectrum in beta-decays provides a robust direct determination of the values of neutrino masses. The planned rhenium beta-decay experiment, called the “Microcalorimeter Arrays for a Rhenium Experiment” (MARE), might probe the absolute mass scale of neutrinos with the same sensitivity as the Karlsruhe tritium neutrino mass (KATRIN) experiment, which is expected to collect data in a near future. In this contribution we discuss the spectrum of emitted electrons close to the end point in the case of the first unique forbidden beta-decay of {sup 79}Se, {sup 107}Pd and {sup 187}Re. It is found that the p{sub 3/2}-wave emission dominates over the s{sub 1/2}-wave. It is shown that the Kurie plot near the end point is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed beta-decay of {sup 3}H.
2012-01-01T23:59:59.000Z
accelerator µ experiments. Some neutrino oscillation experiments compare the flux in two or more detectors://pdg.lbl.gov) Neutrino Mixing A REVIEW GOES HERE Check our WWW List of Reviews (A) Neutrino fluxes and event ratios(A) Neutrino fluxes and event ratios(A) Neutrino fluxes and event ratios(A) Neutrino fluxes and event ratios
Golwala, Sunil
matrices, this probability works out to be: P(Âµ e) = sin2 23 sin2 213 sin2(1.27m2 31L/E). [Next Slide] 3 to lepton number for Majorana neutrinos? "...L mixes and ÂŻ. Thus, a Majorana mass term does not conserve L
Model independent extraction of the axial mass parameter in CCQE anti neutrino-nucleon scattering
Cinabro, David
. In order to understand neutrino oscillations, a detailed knowledge of neutrino scattering between 0 and 10 contribution FP (q2 ) is suppressed by powers of the small lepton-nucleon mass ratio. This leaves only
A Compromise between Neutrino Masses and Collider Signatures in the Type-II Seesaw Model
Wei Chao; Shu Luo; Zhi-zhong Xing; Shun Zhou
2007-09-07T23:59:59.000Z
A natural extension of the standard $SU(2)_{\\rm L} \\times U(1)_{\\rm Y}$ gauge model to accommodate massive neutrinos is to introduce one Higgs triplet and three right-handed Majorana neutrinos, leading to a $6\\times 6$ neutrino mass matrix which contains three $3\\times 3$ sub-matrices $M_{\\rm L}$, $M_{\\rm D}$ and $M_{\\rm R}$. We show that three light Majorana neutrinos (i.e., the mass eigenstates of $\
Neutrino Sources and Properties
Francesco Vissani
2015-05-19T23:59:59.000Z
In this lecture, prepared for PhD students, basic considerations on neutrino interactions, properties and sites of production are overviewed. The detailed content is as follows: Sect. 1, Weak interactions and neutrinos: Fermi coupling; definition of neutrinos; global numbers. Sect. 2, A list of neutrino sources: Explanatory note and examples (solar pp- and supernova-neutrinos). Sect. 3, Neutrinos oscillations: Basic formalism (Pontecorvo); matter effect (Mikheev, Smirnov, Wolfenstein); status of neutrino masses and mixings. Sect. 4, Modifying the standard model to include neutrinos masses: The fermions of the standard model; one additional operator in the standard model (Weinberg); implications. One summary table and several exercises offer the students occasions to check, consolidate and extend their understanding; the brief reference list includes historical and review papers and some entry points to active research in neutrino physics.
Peccei-Quinn symmetry, dark matter, and neutrino mass
Ma, Ernest [Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States)
2014-06-24T23:59:59.000Z
It is pointed out that a residual Z{sub 2} symmetry of the usual anomalous Peccei-Quinn U(1){sub PQ} symmetry (which solves the strong CP problem) may be used for an absolutely stable heavy dark-matter particle in addition to the long-lived axion. The same Z{sub 2} symmetry may also be used to generate radiative neutrino mass.
Searches for New Physics at MiniBooNE: Sterile Neutrinos and Mixing Freedom
Karagiorgi, Georgia S.; /MIT
2010-07-01T23:59:59.000Z
The MiniBooNE experiment was designed to perform a search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations in a region of {Delta}m{sup 2} and sin{sup 2} 2{theta} very different from that allowed by standard, three-neutrino oscillations, as determined by solar and atmospheric neutrino experiments. This search was motivated by the LSND experimental observation of an excess of {bar {nu}}{sub e} events in a {bar {nu}}{sub {mu}} beam which was found compatible with two-neutrino oscillations at {Delta}m{sup 2} {approx} 1 eV{sup 2} and sin{sup 2} 2{theta} < 1%. If confirmed, such oscillation signature could be attributed to the existence of a light, mostly-sterile neutrino, containing small admixtures of weak neutrino eigenstates. In addition to a search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations, MiniBooNE has also performed a search for {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub e} oscillations, which provides a test of the LSND two-neutrino oscillation interpretation that is independent of CP or CPT violation assumptions. This dissertation presents the MiniBooNE {nu}{sub {mu}} {yields} {nu}{sub e} and {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub e} analyses and results, with emphasis on the latter. While the neutrino search excludes the two-neutrino oscillation interpretation of LSND at 98% C.L., the antineutrino search shows an excess of events which is in agreement with the two-neutrino {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub e} oscillation interpretation of LSND, and excludes the no oscillations hypothesis at 96% C.L. Even though the neutrino and antineutrino oscillation results from MiniBooNE disagree under the single sterile neutrino oscillation hypothesis, a simple extension to the model to include additional sterile neutrino states and the possibility of CP violation allows for differences between neutrino and antineutrino oscillation signatures. In view of that, the viability of oscillation models with one or two sterile neutrinos is investigated in global fits to MiniBooNE and LSND data, with and without constraints from other oscillation experiments with similar sensitivities to those models. A general search for new physics scenarios which would lead to effective non-unitarity of the standard 3 x 3 neutrino mixing matrix, or mixing freedom, is also performed using neutrino and antineutrino data available from MiniBooNE.
Connection between the neutrino seesaw mechanism and properties of the Majorana neutrino mass matrix
Ma, Ernest [Physics Department, University of California, Riverside, California 92521 (United States)
2005-06-01T23:59:59.000Z
If it can be ascertained experimentally that the 3x3 Majorana neutrino mass matrix M{sub {nu}} has vanishing determinants for one or more of its 2x2 submatrices, it may be interpreted as supporting evidence for the theoretically well-known canonical seesaw mechanism. I show how these two things are connected and offer a realistic M{sub {nu}} with two zero subdeterminants as an example.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Mertens, Susanne
2015-03-24T23:59:59.000Z
In this contribution the current status and future perspectives of the Karlsruhe Tritium Neutrino (KATRIN) Experiment are presented. The prime goal of this single ?-decay experiment is to probe the absolute neutrino mass scale with a sensitivity of 200 meV (90% CL). We discuss first results of the recent main spectrometer commissioning measurements, successfully verifying the spectrometer’s basic vacuum, transmission and background properties. We also discuss the prospects of making use of the KATRIN tritium source, to search for sterile neutrinos in the multi-keV mass range constituting a classical candidate for Warm Dark Matter. Due to the very high sourcemore »luminosity, a statistical sensitivity down to active-sterile mixing angles of sin˛ ? « less
INTRODUCTION TO THE NEUTRINO PROPERTIES LISTINGS
of neutrino oscillation searches show that the mixing matrix contains two large mixing angles. We cannot oscillations provides us with the values of all neutrino mass-squared differences m2 ij m2 i - m2 j be determined. All confirmed neutrino oscillation experiments using solar, reactor, atmospheric and accelerator
INTRODUCTION TO THE NEUTRINO PROPERTIES LISTINGS
of neutrino oscillation searches show that the mixing matrix contains two large mixing angles. We cannot oscillations provides us with the values of all neutrino mass-squared differences m2 ij m2 i - m2 j be determined. So far solar, reactor, atmospheric and accelerator neutrino oscillation experiments can
Majorana neutrino masses and the neutrinoless double-beta decay
Faessler, A. [University of Tuebingen, Institute of Theoretical Physics (Germany)], E-mail: amand.faessler@uni-tuebingen.de
2006-12-15T23:59:59.000Z
Neutrinoless double-beta decay is forbidden in the Standard Model of electroweak and strong interaction but allowed in most Grand Unified Theories (GUTs). Only if the neutrino is a Majorana particle (identical with its antiparticle) and if it has a mass is neutrinoless double-beta decay allowed. Apart from one claim that the neutrinoless double-beta decay in {sup 76}Ge is measured, one has only upper limits for this transition probability. But even the upper limits allow one to give upper limits for the electron Majorana neutrino mass and upper limits for parameters of GUTs and the minimal R-parity-violating supersymmetric model. One further can give lower limits for the vector boson mediating mainly the right-handed weak interaction and the heavy mainly right-handed Majorana neutrino in left-right symmetric GUTs. For that, one has to assume that the specific mechanism is the leading one for neutrinoless double-beta decay and one has to be able to calculate reliably the corresponding nuclear matrix elements. In the present work, one discusses the accuracy of the present status of calculating of the nuclear matrix elements and the corresponding limits of GUTs and supersymmetric parameters.
Hybrid Textures of the Right-Handed Majorana Neutrino Mass Matrix
Dev, S; Singh, Lal
2013-01-01T23:59:59.000Z
We perform a systematic study of neutrino mass matrices having a vanishing cofactor and an equality between two cofactors of the mass matrix. Such texture structures of the effective neutrino mass matrix arise from type-I seesaw mechanism when the Dirac neutrino mass matrix is diagonal with equal elements and the right-handed Majorana neutrino mass matrix has hybrid textures with one equality of matrix elements and one zero matrix element. For three right-handed neutrinos there are sixty possible hybrid textures out of which only six are excluded by the present experimental data. We show that such textures can be derived using discrete symmetries. The predictions of experimentally allowed textures are examined for unknown parameters such as the effective Majorana mass of the electron neutrino and the Dirac-type CP-violating phase.
Form invariance and symmetry in the neutrino mass matrix
Lashin, E. I. [Department of Physics and Astronomy, College of Science, King Saud University, Riyadh (Saudi Arabia); Ain Shams University, Faculty of Science, Cairo 11566 (Egypt); Nasri, S.; Malkawi, E. [Department of Physics, UAE University, P.O. Box 17551, Al-Ain (United Arab Emirates); Chamoun, N. [Physics Department, HIAST, P.O. Box 31983, Damascus (Syrian Arab Republic)
2011-01-01T23:59:59.000Z
We present the general form of the unitary matrices keeping invariant the Majorana neutrino mass matrix of specific texture suitable for explaining oscillation data. In the case of the tri-bimaximal pattern with two degenerate masses, we give a specific realization of the underlying U(1) symmetry which can be uplifted to a symmetry in a complete theory including charged leptons. For this, we present a model with three light SM-like Higgs doublets and one heavy Higgs triplet and find that one can accommodate the hierarchy of the charged-lepton masses. The lepton mass spectrum can also be achieved in another model extending the SM with three SM-singlet scalars transforming nontrivially under the flavor symmetry. We discuss how such a model has room for generating enough baryon asymmetry through leptogenesis in the framework of type-I and -II seesaw mechanisms.
Los Alamos Science, Number 25 -- 1997: Celebrating the neutrino
Cooper, N.G. [ed.] [ed.
1997-12-31T23:59:59.000Z
This issue is devoted to the neutrino and its remaining mysteries. It is divided into the following areas: (1) The Reines-Cowan experiment -- detecting the poltergeist; (2) The oscillating neutrino -- an introduction to neutrino masses and mixing; (3) A brief history of neutrino experiments at LAMPF; (4) A thousand eyes -- the story of LSND (Los Alamos neutrino oscillation experiment); (5) The evidence for oscillations; (6) The nature of neutrinos in muon decay and physics beyond the Standard Model; (7) Exorcising ghosts -- in pursuit of the missing solar neutrinos; (8) MSW -- a possible solution to the solar neutrino problem; (8) Neutrinos and supernovae; and (9) Dark matter and massive neutrinos.
Model-independent Constraint on the Neutrino Mass Spectrum from the Neutrinoless Double Beta Decay
Zhi-zhong Xing
2002-02-22T23:59:59.000Z
We present a concise formula to relate the effective mass term of the neutrinoless double beta decay to a single neutrino mass, two Majorana CP-violating phases and four observables of neutrino oscillations for a generic neutrino mass spectrum. If the alleged evidence for the neutrinoless double beta decay is taken into account, one may obtain a rough but model-independent constraint on the absolute scale of neutrino masses -- it is most likely to be in the range between 0.1 eV and 1 eV.
Pulsar kicks from neutrino oscillations
Alexander Kusenko
2004-09-27T23:59:59.000Z
Neutrino oscillations in a core-collapse supernova may be responsible for the observed rapid motions of pulsars. Given the present bounds on the neutrino masses, the pulsar kicks require a sterile neutrino with mass 2-20 keV and a small mixing with active neutrinos. The same particle can be the cosmological dark matter. Its existence can be confirmed the by the X-ray telescopes if they detect a 1-10 keV photon line from the decays of the relic sterile neutrinos. In addition, one may be able to detect gravity waves from a pulsar being accelerated by neutrinos in the event of a nearby supernova.
Bounds on neutrino masses from leptogenesis in type-II seesaw models
Sahu, Narendra; Sankar, S. Uma [Department of Physics, Indian Institute of Technology, Bombay, Mumbai 400076 (India)
2005-01-01T23:59:59.000Z
The presence of the triplet {delta}{sub L} in left-right symmetric theories leads to type-II seesaw mechanism for the neutrino masses. In these models, assuming a normal mass hierarchy for the heavy Majorana neutrinos, we derive a lower bound on the mass of the lightest of heavy Majorana neutrinos from the leptogenesis constraint. From this bound we establish a consistent picture for the hierarchy of heavy Majorana neutrinos in a class of left-right symmetric models in which we identify the neutrino Dirac mass matrix with that of Fritzsch type charged lepton mass matrix. It is shown that these values are compatible with the current neutrino oscillation data.
Majorana Neutrino Masses from Neutrinoless Double Beta Decay and Cosmology
V. Barger; K. Whisnant
1999-04-08T23:59:59.000Z
When three Majorana neutrinos describe the solar and atmospheric neutrino data via oscillations, a nonzero measurement of neutrinoless double beta ($0\
Variations on Four-Neutrino Oscillations
V. Barger; S. Pakvasa; T. J. Weiler; K. Whisnant
1998-06-09T23:59:59.000Z
We make a model-independent analysis of all available data that indicate neutrino oscillations. Using probability diagrams, we confirm that a mass spectrum with two nearly degenerate pairs of neutrinos separated by a mass gap of $\\simeq1$ eV is preferred over a spectrum with one mass eigenstate separated from the others. We derive some new relations among the four-neutrino mixing matrix elements. We design four-neutrino mass matrices with three active neutrinos and one sterile neutrino that naturally incorporate maximal oscillations of atmospheric $\
Neutrino mass, bulk majoron and neutrinoless double beta decay
R. N. Mohapatra; A. Perez-Lorenzana; C. A. de S. Pires
2000-08-15T23:59:59.000Z
A new economical model for neutrino masses is proposed in the context of brane bulk scenarios for particle physics, where global B-L symmetry of the standard model is broken spontaneously by a gauge singlet Higgs field in the bulk. This leads to a bulk majoron whose KK excitations may make it visible if neutrinoless double beta decay if the string scale is close to a TeV. It also leads to neutron-anti-neutron oscillation process with transition times which can be in the range accessible to proposed experiments.
Cahill, K E
1999-01-01T23:59:59.000Z
Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle theta_nu characterizes the kind of the neutrinos, with theta_nu=0 for Dirac neutrinos and theta_nu=pi/2 for Majorana neutrinos. At theta_nu = 0 baryon-minus-lepton number is conserved. If theta_nu is approximately zero, the six neutrino masses coalesce into three nearly degenerate pairs. Thus the tiny mass differences exhibited in the solar and atmospheric neutrino experiments are naturally explained by the approximate conservation of B-L. Neutrinos are nearly Dirac fermions. This B-L model leads to these predictions: neutrinos oscillate mainly between flavor eigenfields and sterile eigenfields, and so neither KARMEN, nor SNO, nor BooNE will detect the appearance of neutrinos or antineutrinos; neutrinos may well be of cosmological importance; in principle the disappearance of the tau neutrino should be observable; and neutrinoless double-beta d...
Kevin Cahill
2000-06-19T23:59:59.000Z
Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle theta_nu characterizes the kind of the neutrinos, with theta_nu=0 for Dirac neutrinos and theta_nu=pi/2 for Majorana neutrinos. At theta_nu = 0 baryon-minus-lepton number is conserved. If theta_nu is approximately zero, the six neutrino masses coalesce into three nearly degenerate pairs. Thus the tiny mass differences exhibited in the solar and atmospheric neutrino experiments are naturally explained by the approximate conservation of B-L. Neutrinos are nearly Dirac fermions. This B-L model leads to these predictions: neutrinos oscillate mainly between flavor eigenfields and sterile eigenfields, and so the appearance of neutrinos and antineutrinos is suppressed; neutrinos may well be of cosmological importance; in principle the disappearance of the tau neutrino should be observable; and neutrinoless double-beta decay is suppressed by an extra factor of 10^(-5) and so will not be seen in the Heidelberg/Moscow, IGEX, GENIUS, or CUORE experiments.
Light neutrino mass spectrum with one or two right-handed singlet fermions added
Darius Jurciukonis; Thomas Gajdosik; Andrius Juodagalvis
2014-10-16T23:59:59.000Z
We analyse two cases of the minimal extension of the Standard Model when one or two right-handed fields are added to the three left-handed fields. A second Higgs doublet (two Higgs doublet model - 2HDM) is included in our model. We calculate one-loop radiative corrections to the mass parameters which produce mass terms for the neutral leptons. In both cases we numerically analyse light neutrino masses as functions of the heavy neutrino masses. Parameters of the model are varied to find light neutrino masses that are compatible with experimental data of solar and atmospheric neutrino mass differences for normal hierarchy. We choose values for the parameters of the tree-level by numerical scans, where we look for the best agreement between computed and experimental neutrino oscillation angles.
An Axial Vector Nature of a Neutrino with an Electroweak Mass
Rasulkhozha S. Sharafiddinov
2011-11-09T23:59:59.000Z
A classification of elementary particles with respect to C-operation admits the existence of truly neutral types of fermions. Among them one can find both a Dirac and a Majorana neutrinos of an electroweak nature. Their mass includes the electric and weak parts, in the presence of which a neutrino has the anapole charge, charge radius and electric dipole moment. They constitute the paraneutrino of true neutrality, for example, at the neutrino interaction with a spinless nucleus of an axial-vector current. We derive the united equations which relate the structural components of mass to anapole, charge radius and electric dipole of each truly neutral neutrino at the level of flavour symmetry. Such a principle can explain the C-noninvariant nature of neutrinos and fields in the framework of constancy law of the size implied from the multiplication of a weak mass of the C-odd neutrino by its electric mass. From this point of view, all neutrinos of C-antisymmetricality regardless of the difference in masses of an axial-vector character, possess the same anapole with his radius as well as the identical electric dipole. Their analysis together with earlier measurements of an electric dipole moment of neutrino gives the right to accept not only the existence of truly neutral types of Dirac neutrinos and fields but also the availability of mass structure in them as the one of experimentally established facts.
Ultra-low Q values for neutrino mass measurements
Joachim Kopp; Alexander Merle
2010-04-21T23:59:59.000Z
We investigate weak nuclear decays with extremely small kinetic energy release (Q value) and thus extremely good sensitivity to the absolute neutrino mass scale. In particular, we consider decays into excited daughter states, and we show that partial ionization of the parent atom can help to tune Q values to low-Q decays might only be feasible if no ionization is required, and if future improvements in isotope production technology, nuclear mass spectroscopy, and atomic structure calculations are possible. Experiments using ions, however, are extremely challenging due to the large number of ions that must be stored. New precision data on nuclear excitation levels could help to identify further isotopes with low-Q decay modes and possibly less challenging requirements.
Matsuda, Koichi; Nishiura, Hiroyuki [Center for High Energy Physics, Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Faculty of Information Science and Technology, Osaka Institute of Technology, Hirakata, Osaka 573-0196 (Japan)
2006-08-01T23:59:59.000Z
We reconsider a universal mass matrix model which has a seesaw-invariant structure with four-zero texture common to all quarks and leptons. The Cabibbo-Kobayashi-Maskawa (CKM) quark and Maki-Nakagawa-Sakata (MNS) lepton mixing matrices of the model are analyzed analytically. We show that the model can be consistent with all the experimental data of neutrino oscillation and quark mixings by tuning free parameters of the model. It is also shown that the model predicts a relatively large value for the (1, 3) element of the MNS lepton mixing matrix (U{sub MNS}){sub 13}{sup 2}{approx_equal}(0.041-9.6)x10{sup -2}. Using the seesaw mechanism, we also discuss the conditions for the components of the Dirac and the right-handed Majorana neutrino mass matrices which lead to the neutrino mass matrix consistent with the experimental data.
Minakata, H.; /Tokyo Metropolitan U.; Nunokawa, H.; /Rio de Janeiro, Pont. U. Catol.; Parke, Stephen J.; /Fermilab; Zukanovich Funchal, R.; /Sao Paulo U.
2006-09-01T23:59:59.000Z
In this talk, the authors discuss the possibility of determining the neutrino mass hierarchy by comparing the two effective atmospheric neutrino mass squared differences measured, respectively, in electron, and in muon neutrino disappearance oscillation experiments. if the former, is larger (smaller) than the latter, the mass hierarchy is of normal (inverted) type. They consider two very high precision (a few per mil) measurements of such mass squared differences by the phase II of the T2K (Tokai-to-Kamioka) experiment and by the novel Moessbauer enhanced resonant {bar {nu}}{sub e} absorption technique. Under optimistic assumptions for the systematic errors of both measurements, they determine the region of sensitivities where the mass hierarchy can be distinguished. Due to the tight space limitation, they present only the general idea and show a few most important plots.
Investigation of Neutrino Properties with Bolometric Detectors
Heeger, Karsten M [University of Wisconsin & Yale University
2014-11-01T23:59:59.000Z
Neutrino mass and mixing are amongst the major discoveries of the past decade. The particle nature of neutrinos and the hierarchy of mass eigenstates, however, are unknown. Neutrinoless double beta-decay (0???) is the only known mechanism to test whether neutrinos are their own antiparticles. The observation of 0??? would imply lepton number violation and show that neutrinos have Majorana mass. This report describes research activities performed at the University of Wisconsin in 2011-2014 aimed at the search for 0??? with CUORE-0 and CUORE with the goal of exploring the inverted mass hierarchy region and probing an effective neutrino mass of ~40- 120 meV.
Status and Prospects of Reactor Neutrino Experiments
Kim, Soo-Bong
2015-01-01T23:59:59.000Z
New generation of three reactor neutrino experiments have made definitive measurements of the smallest neutrino mixing angle theta13 in 2012, based on the disappearance of electron antineutrinos. More precise measurements of the mixing angle have been made as well as the squared mass difference between electron neutrinos. A rather large value of theta13 has opened a new window to find the CP violation phase and to determine the neutrino mass hierarchy. Future reactor experiments, JUNO and RENO50, are proposed to determine the neutrino mass hierarchy and to make highly precise measurements of theta12, the squared mass difference between neutrino masses 2 and 1, and the squared mass difference between electron neutrinos.
A. Hernandez-Galeana; N. S. Mankoc Borstnik
2011-12-19T23:59:59.000Z
The {\\it theory unifying spin and charges and predicting families}, proposed by N.S.M.B., predicts at the low energy regime two (in the mixing matrix elements decoupled) groups of four families. There are two kinds of contributions to mass matrices in this theory. One kind distinguishes on the tree level only among the members of one family, that is among the $u$-quark, $d$-quark, neutrino and electron, the left and right handed, while the other kind distinguishes only among the families. Mass matrices for $d$-quarks and electrons are on the tree level correspondingly strongly correlated and so are mass matrices for $u$-quarks and neutrinos, up to the term, the Majorana term, which is nonzero only for right handed neutrinos. Beyond the tree level both kinds of contributions start to contribute coherently and it is expected that a detailed study of properties of mass matrices beyond the tree level explains drastic differences in masses and mixing matrices between quarks and leptons. We report in this paper on analysis of one loop corrections to the tree level fermion masses and mixing matrices. Loop diagrams are mediated by the gauge bosons and the two kinds of scalar fields. A detailed numerical analysis of fermion masses and mixing, including neutrinos, within this scenario is in progress and preparation.
Attempt at a gauge-theory-based explanation of the mass spectrum and number of light neutrinos
Dyatlov, I. T. [Russian Academy of Sciences, Petersburg Nuclear Physics Institute (Russian Federation)
2009-12-15T23:59:59.000Z
The symplectic group Sp(n/2) of invariance of flavors of n Majorana states (n is even) does not admit the existence of invariant Majorana masses. Only a specific mass matrix involving diagonal and off-diagonal elements is possible. A mass matrix as a result of spontaneous flavor- and chiral-symmetry breaking may appear here only in the case where the number of flavors is n = 6 and only together with spontaneous R- and L-symmetry violation-that is, parity violation. As a result, three light and three heavy Dirac particles (neutrinos) are present if the seesaw mechanism is operative. Special features of the observed spectrum of light neutrinos-in particular, the fact that two states are far off the third one-can be explained by simple properties of the mass matrices arising in Sp(3). The arrangement of states corresponds to an ordinary mass hierarchy. The mixing angles for physical neutrinos cannot be determined without understanding the mechanisms responsible for the formation of the charged-lepton spectrum and the weak current of Majorana states.
Constraints on neutrinoless double beta decay from neutrino oscillation experiments
S. M. Bilenky; C. Giunti; M. Monteno
1997-01-15T23:59:59.000Z
We show that, in the framework of a general model with mixing of three Majorana neutrinos and a neutrino mass hierarchy, the results of the Bugey and Krasnoyarsk reactor neutrino oscillation experiments imply strong limitations for the effective Majorana mass || that characterizes the amplitude of neutrinoless double beta decay. We obtain further limitations on || from the data of the atmospheric neutrino experiments. We discuss the possible implications of the results of the future long baseline neutrino oscillation experiments for neutrinoless double beta decay.
The fluxes of CN neutrinos from the Sun in case of mixing in a spherical layer in the solar core
Kopylov, Anatoly; Petukhov, Valery, E-mail: kopylov@inr.ru, E-mail: beril@inr.ru [Institute of Nuclear Research of Russian Academy of Sciences, Prospect of 60th Anniversary of October Revolution 7A, 117312 Moscow (Russian Federation)
2012-03-01T23:59:59.000Z
The results of the calculation are presented for the fluxes of CN neutrinos from the Sun in case of mixing in a spherical layer in the solar core, consistent with the seismic data and with the measured solar neutrino fluxes. It is shown that a substantial increase of the flux of {sup 13}N neutrinos can be gained in this case. The possible implications for experiment are discussed.
Neutrinoless double beta decay in four-neutrino models
Anna Kalliomaki; Jukka Maalampi
2000-03-29T23:59:59.000Z
The most stringent constraint on the so-called effective electron neutrino mass from the present neutrinoless double beta decay experiments is |M_{ee}| < 0.2 eV, while the planned next generation experiment GENIUS is anticipated to reach a considerably more stringent limit |M_{ee}|< 0.001 eV. We investigate the constraints these bounds set on the neutrino masses and mixings of neutrinos in four-neutrino models where there exists a sterile neutrino along with the three ordinary neutrinos. We find that the GENIUS experiment would be sensitive to the electron neutrino masses down to the limit m_{\
Neutrino mixings and leptonic CP violation from CKM matrix and Majorana phases
Agarwalla, Sanjib Kumar; Parida, M. K.; Mohapatra, R. N.; Rajasekaran, G. [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Institute of Mathematical Sciences, Chennai 600113 (India)
2007-02-01T23:59:59.000Z
The high scale mixing unification hypothesis recently proposed by three of us (R. N. M., M. K. P. and G. R.) states that if at the seesaw scale the quark and lepton mixing matrices are equal, then for quasidegenerate neutrinos radiative corrections can lead to large solar and atmospheric mixings and small reactor angle at the weak scale in agreement with data. Evidence for quasidegenerate neutrinos could, within this framework, be interpreted as being consistent with quark-lepton unification at high scale. In the current work, we extend this model to show that the hypothesis works quite successfully in the presence of CP-violating phases (which were set to zero in the first paper). In the case where the Pontecorvo-Maki-Nakagawa-Sakata matrix is identical to the Cabibbo-Kobayashi-Maskawa quark-mixing matrix at the seesaw scale, with a Dirac phase but no Majorana phase, the low energy Dirac phase is predicted to be ({approx_equal}0.3 deg.) and leptonic CP-violation parameter J{sub CP}{approx_equal}(4-8)x10{sup -5} and {theta}{sub 13}=3.5 deg. If on the other hand, the Pontecorvo-Maki-Nakagawa-Sakata matrix is assumed to also have non-negligible Majorana phase(s) initially, the resulting theory damps radiative magnification phenomenon for a large range of parameters but nevertheless has enough parameter space to give the two necessary large neutrino mixing angles. In this case, one has {theta}{sub 13}=3.5 deg. -10 deg. and vertical bar J{sub CP} vertical bar as large as 0.02-0.04 which are accessible to long baseline neutrino oscillation experiments.
Neutrino mass matrices with a texture zero and a vanishing minor
Dev, S.; Verma, Surender; Gupta, Shivani; Gautam, R. R. [Department of Physics, Himachal Pradesh University, Shimla 171005 (India)
2010-03-01T23:59:59.000Z
We study the implications of the simultaneous existence of a texture zero and a vanishing minor in the neutrino mass matrix. There are 36 possible texture structures of this type, 21 of which reduce to two texture zero cases which have, already, been extensively studied. Of the remaining 15 textures only six are allowed by the current data. We examine the phenomenological implications of the allowed texture structures for Majorana type CP-violating phases, 1-3 mixing angle, and Dirac type CP-violating phase. All these possible textures can be generated through the seesaw mechanism and realized in the framework of discrete Abelian flavor symmetry. We present the symmetry realization of these texture structures.
Neutrinos and Collider Physics
Frank F. Deppisch; P. S. Bhupal Dev; Apostolos Pilaftsis
2015-08-04T23:59:59.000Z
We review the collider phenomenology of neutrino physics and the synergetic aspects at energy, intensity and cosmic frontiers to test the new physics behind the neutrino mass mechanism. In particular, we focus on seesaw models within the minimal setup as well as with extended gauge and/or Higgs sectors, and on supersymmetric neutrino mass models with seesaw mechanism and with $R$-parity violation. In the simplest Type-I seesaw scenario with sterile neutrinos, we summarize and update the current experimental constraints on the sterile neutrino mass and its mixing with the active neutrinos. We also discuss the future experimental prospects of testing the seesaw mechanism at colliders and in related low-energy searches for rare processes, such as lepton flavor violation and neutrinoless double beta decay. The implications of the discovery of lepton number violation at the LHC for leptogenesis are also studied.
Neutrinos and Collider Physics
Frank F. Deppisch; P. S. Bhupal Dev; Apostolos Pilaftsis
2015-03-09T23:59:59.000Z
We review the collider phenomenology of neutrino physics and the synergetic aspects at energy, intensity and cosmic frontiers to test the new physics behind the neutrino mass mechanism. In particular, we focus on seesaw models within the minimal setup as well as with extended gauge and/or Higgs sectors, and on supersymmetric neutrino mass models with seesaw mechanism and with $R$-parity violation. In the simplest Type-I seesaw scenario with sterile neutrinos, we summarize and update the current experimental constraints on the sterile neutrino mass and its mixing with the active neutrinos. We also discuss the future experimental prospects of testing the seesaw mechanism at colliders and in related low-energy searches for rare processes, such as lepton flavor violation and neutrinoless double beta decay. The implications of the discovery of lepton number violation at the LHC for leptogenesis are also studied.
Neutrinos and Collider Physics
Deppisch, Frank F; Pilaftsis, Apostolos
2015-01-01T23:59:59.000Z
We review the collider phenomenology of neutrino physics and the synergetic aspects at energy, intensity and cosmic frontiers to test the new physics behind the neutrino mass mechanism. In particular, we focus on seesaw models within the minimal setup as well as with extended gauge and/or Higgs sectors, and on supersymmetric neutrino mass models with seesaw mechanism and with $R$-parity violation. In the simplest Type-I seesaw scenario with sterile neutrinos, we summarize and update the current experimental constraints on the sterile neutrino mass and its mixing with the active neutrinos. We also discuss the future experimental prospects of testing the seesaw mechanism at colliders and in related low-energy searches for rare processes, such as lepton flavor violation and neutrinoless double beta decay. The implications of the discovery of lepton number violation at the LHC for leptogenesis are also studied.
Neutrinos Are Nearly Dirac Fermions
Cahill, K E
1999-01-01T23:59:59.000Z
Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle theta_nu characterizes the kind of the neutrinos, with theta_nu = 0 for Dirac neutrinos and theta_nu = pi/2 for Majorana neutrinos. If theta_nu = 0, then baryon-minus-lepton number is conserved. When theta_nu is approximately zero, the six neutrino masses coalesce into three nearly degenerate pairs. Thus the smallness of the differences in neutrino masses exhibited in the solar and atmospheric neutrino experiments and the stringent limits on neutrinoless double-beta decay are naturally explained if B-L is approximately conserved and neutrinos are nearly Dirac fermions. If one sets theta_nu = 0.0005, suppresses inter-generational mixing, and imposes a quark-like mass hierarchy, then one may fit the essential features of the solar, reactor, and atmospheric neutrino experiments with otherwise random mass matrices in the eV range. This B-L model le...
M. K. Parida; Sudhanwa Patra
2013-01-14T23:59:59.000Z
In TeV scale left-right symmetric models, new dominant predictions to neutrinoless double beta decay and light neutrino masses are in mutual contradiction because of large contribution to the latter through popular seesaw mechanisms. We show that in a class of left-right models with high-scale parity restoration, these results coexist without any contravention with neutrino oscillation data and the relevant formula for light neutrino masses is obtained via gauged inverse seesaw mechanism. The most dominant contribution to the double beta decay is shown to be via $W^-_L- W^-_R$ mediation involving both light and heavy neutrino exchanges, and the model predictions are found to discriminate whether the Dirac neutrino mass is of quark-lepton symmetric origin or without it. We also discuss associated lepton flavor violating decays.
Neutrino Mass Matrices with Two Equalities Between the Elements or Cofactors
S. Dev; Radha Raman Gautam; Lal Singh
2013-04-26T23:59:59.000Z
We study the implications of the existence of two equalities between the elements or cofactors of the neutrino mass matrix. There are sixty five structures of this type for each case. Phenomenological implications for unknown parameters like the effective Majorana mass of the electron neutrino and CP-violating phases are examined for the viable cases. To illustrate how such forms of the neutrino mass matrices may be realized, we also present a simple $A_4$ model for one of the classes in each case.
Neutrino Mass Matrices with Two Equalities Between the Elements or Cofactors
Dev, S; Singh, Lal
2013-01-01T23:59:59.000Z
We study the implications of the existence of two equalities between the elements or cofactors of the neutrino mass matrix. There are sixty five structures of this type for each case. Phenomenological implications for unknown parameters like the effective Majorana mass of the electron neutrino and CP-violating phases are examined for the viable cases. To illustrate how such forms of the neutrino mass matrices may be realised, we, also, present a simple $A_4$ model for one of the classes in each case.
Mass Mixing, the Fourth Generation, and the Kinematic Higgs Mechanism
Alexander N. Jourjine
2010-08-25T23:59:59.000Z
We describe how to construct chiral fermion mass terms using Dirac-Kahler (DK) spinors. Classical massive DK spinors are shown to be equivalent to four generations of Dirac spinors with equal mass coupled to a background U(2,2) gauge field. Quantization breaks U(2,2) to U(2)xU(2), lifts mass spectrum degeneracy, and generates a non-trivial mass mixing matrix.
Improved measurements of the neutrino mixing angle $?_{13}$ with the Double Chooz detector
Y. Abe; J. C. dos Anjos; J. C. Barriere; E. Baussan; I. Bekman; M. Bergevin; T. J. C. Bezerra; L. Bezrukov; E. Blucher; C. Buck; J. Busenitz; A. Cabrera; E. Caden; L. Camilleri; R. Carr; M. Cerrada; P. -J. Chang; E. Chauveau; P. Chimenti; A. P. Collin; E. Conover; J. M. Conrad; J. I. Crespo-Anadón; K. Crum; A. S. Cucoanes; E. Damon; J. V. Dawson; J. Dhooghe; D. Dietrich; Z. Djurcic; M. Dracos; M. Elnimr; A. Etenko; M. Fallot; F. von Feilitzsch; J. Felde; S. M. Fernandes; V. Fischer; D. Franco; M. Franke; H. Furuta; I. Gil-Botella; L. Giot; M. Göger-Neff; L. F. G. Gonzalez; L. Goodenough; M. C. Goodman; C. Grant; N. Haag; T. Hara; J. Haser; M. Hofmann; G. A. Horton-Smith; A. Hourlier; M. Ishitsuka; J. Jochum; C. Jollet; F. Kaether; L. N. Kalousis; Y. Kamyshkov; D. M. Kaplan; T. Kawasaki; E. Kemp; H. de Kerret; D. Kryn; M. Kuze; T. Lachenmaier; C. E. Lane; T. Lasserre; A. Letourneau; D. Lhuillier; H. P. Lima Jr; M. Lindner; J. M. López-Castańo; J. M. LoSecco; B. Lubsandorzhiev; S. Lucht; J. Maeda; C. Mariani; J. Maricic; J. Martino; T. Matsubara; G. Mention; A. Meregaglia; T. Miletic; R. Milincic; A. Minotti; Y. Nagasaka; Y. Nikitenko; P. Novella; L. Oberauer; M. Obolensky; A. Onillon; A. Osborn; C. Palomares; I. M. Pepe; S. Perasso; P. Pfahler; A. Porta; G. Pronost; J. Reichenbacher; B. Reinhold; M. Röhling; R. Roncin; S. Roth; B. Rybolt; Y. Sakamoto; R. Santorelli; A. C. Schilithz; S. Schönert; S. Schoppmann; M. H. Shaevitz; R. Sharankova; S. Shimojima; D. Shrestha; V. Sibille; V. Sinev; M. Skorokhvatov; E. Smith; J. Spitz; A. Stahl; I. Stancu; L. F. F. Stokes; M. Strait; A. Stüken; F. Suekane; S. Sukhotin; T. Sumiyoshi; Y. Sun; R. Svoboda; K. Terao; A. Tonazzo; H. H. Trinh Thi; G. Valdiviesso; N. Vassilopoulos; C. Veyssiere; M. Vivier; S. Wagner; N. Walsh; H. Watanabe; C. Wiebusch; L. Winslow; M. Wurm; G. Yang; F. Yermia; V. Zimmer
2015-01-21T23:59:59.000Z
The Double Chooz experiment presents improved measurements of the neutrino mixing angle $\\theta_{13}$ using the data collected in 467.90 live days from a detector positioned at an average distance of 1050 m from two reactor cores at the Chooz nuclear power plant. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties with respect to previous publications, whereas the efficiency of the $\\bar\
Neutrino Mixings and Leptonic CP Violation from CKM Matrix and Majorana Phases
S. K. Agarwalla; M. K. Parida; R. N. Mohapatra; G. Rajasekaran
2007-04-11T23:59:59.000Z
The high scale mixing unification hypothesis recently proposed by three of us (R. N. M., M. K. P. and G. R.) states that if at the seesaw scale, the quark and lepton mixing matrices are equal then for quasi-degenerate neutrinos, radiative corrections can lead to large solar and atmospheric mixings and small reactor angle at the weak scale in agreement with data. Evidence for quasi-degenerate neutrinos could, within this framework, be interpreted as a sign of quark-lepton unification at high scale. In the current work, we extend this model to show that the hypothesis works quite successfully in the presence of CP violating phases (which were set to zero in the first paper). In the case where the PMNS matrix is identical to the CKM matrix at the seesaw scale, with a Dirac phase but no Majorana phase, the low energy Dirac phase is predicted to be ($\\simeq 0.3^{\\circ}$) and leptonic CP-violation parameter $J_{CP} \\simeq (4 - 8)\\times 10^{-5}$ and $\\theta_{13} = 3.5^{\\circ}$. If on the other hand, the PMNS matrix is assumed to also have Majorana phases initially, the resulting theory damps radiative magnification phenomenon for a large range of parameters but nevertheless has enough parameter space to give the two necessary large neutrino mixing angles. In this case, one has $\\theta_{13} = 3.5^{\\circ} - 10^{\\circ}$ and $|J_{CP}|$ as large as $0.02-0.04$ which are accessible to long baseline neutrino oscillation experiments.
Higgs Vacuum Stability, Neutrino Mass, and Dark Matter
Wei Chao; Matthew Gonderinger; Michael J. Ramsey-Musolf
2012-10-22T23:59:59.000Z
Recent results from ATLAS and CMS point to a narrow range for the Higgs mass: $M_H\\in[ 124, 126] {\\rm GeV}$. Given this range, a case may be made for new physics beyond the Standard Model (SM) because of the resultant vacuum stability problem, i.e., the SM Higgs quartic coupling may run to negative values at a scale below the Planck scale. We study representative minimal extensions of the SM that can keep the SM Higgs vacuum stable to the Planck scale by introducing new scalar or fermion interactions at the TeV scale while solving other phenomenological problems. In particular, we consider the type-II seesaw model, which is introduced to explain the non-zero Majorana masses of the active neutrinos. Similarly, we observe that if the stability of the SM Higgs vacuum is ensured by the running of the gauge sector couplings, then one may require a series of new electroweak multiplets, the neutral component of which can be cold dark matter candidate. Stability may also point to a new U(1) gauge symmetry, in which the SM Higgs carries non-zero charge.
Charge dependent relation between the masses of different generations and Neutrino masses
Branislav Sazdovic
2015-01-29T23:59:59.000Z
Despite the enormous achievements, the Standard model of Particle physics can not be consider as complete theory of fundamental interactions. Among other things, it can not describe the gravitational interaction and it depends on 19 parameters. The Standard model includes 12 fermions (matter elementary particles with spin $\\frac{1}{2}$) which are divided in three generations, groups with same interactions but different masses. Each generation can be classified into two leptons (with electric charges $Q=-1$, electron-like and $Q=0$, neutrino) and two quarks (with electric charges $Q=-\\frac{1}{3}$, down-type and $Q=\\frac{2}{3}$, up-type). However, the understanding of the relationship between generations and ratio of masses of different generations are unknown. Here we show that there exists the simple relation between masses of different generations which depend only on the electric charges for $Q=-1,\\, \\, Q=-\\frac{1}{3}$ and $Q=\\frac{2}{3}$. It is in pretty good agreement with experimental data. Assuming that the same relation valid for $Q=0$, we are able to calculate neutrino masses. Therefore, our results could pave the way for further investigations beyond Standard model.
Diffuse supernova neutrinos: oscillation effects, stellar cooling and progenitor mass dependence
Lunardini, Cecilia [Arizona State University, Tempe, AZ, 85287-1504 (United States); Tamborra, Irene, E-mail: Cecilia.Lunardini@asu.edu, E-mail: tamborra@mpp.mpg.de [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6, 80805 München (Germany)
2012-07-01T23:59:59.000Z
We estimate the diffuse supernova neutrino background (DSNB) using the recent progenitor-dependent, long-term supernova simulations from the Basel group and including neutrino oscillations at several post-bounce times. Assuming multi-angle matter suppression of collective effects during the accretion phase, we find that oscillation effects are dominated by the matter-driven MSW resonances, while neutrino-neutrino collective effects contribute at the 5–10% level. The impact of the neutrino mass hierarchy, of the time-dependent neutrino spectra and of the diverse progenitor star population is 10% or less, small compared to the uncertainty of at least 25% of the normalization of the supernova rate. Therefore, assuming that the sign of the neutrino mass hierarchy will be determined within the next decade, the future detection of the DSNB will deliver approximate information on the MSW-oscillated neutrino spectra. With a reliable model for neutrino emission, its detection will be a powerful instrument to provide complementary information on the star formation rate and for learning about stellar physics.
Mondragon, A.; Mondragon, M.; Peinado, E. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, 01000 Mexico D.F. (Mexico)
2007-10-01T23:59:59.000Z
The mass matrices of the charged leptons and neutrinos, previously derived in a minimal S{sub 3}-invariant extension of the standard model, were reparametrized in terms of their eigenvalues. We obtained explicit, analytical expressions for all entries in the neutrino mixing matrix, V{sub PMNS}, the neutrino mixing angles, and the Majorana phases as functions of the masses of charged leptons and neutrinos in excellent agreement with the latest experimental values. The resulting V{sub PMNS} matrix is very close to the tribimaximal form of the neutrino mixing matrix. We also derived explicit, analytical expressions for the matrices of the Yukawa couplings and computed the branching ratios of some selected flavor-changing neutral current processes as functions of the masses of the charged leptons and the neutral Higgs bosons. We find that the S{sub 3}xZ{sub 2} flavor symmetry and the strong mass hierarchy of the charged leptons strongly suppress the FCNC processes in the leptonic sector well below the present experimental upper bounds by many orders of magnitude.
Dark matter and strong electroweak phase transition in a radiative neutrino mass model
Ahriche, Amine [Department of Physics, University of Jijel, PB 98 Ouled Aissa, DZ-18000 Jijel (Algeria); Nasri, Salah, E-mail: aahriche@ictp.it, E-mail: snasri@uaeu.ac.ae [Physics Department, UAE University, POB 17551, Al Ain (United Arab Emirates)
2013-07-01T23:59:59.000Z
We consider an extension of the standard model (SM) with charged singlet scalars and right handed (RH) neutrinos all at the electroweak scale. In this model, the neutrino masses are generated at three loops, which provide an explanation for their smallness, and the lightest RH neutrino, N{sub 1}, is a dark matter candidate. We find that for three generations of RH neutrinos, the model can be consistent with the neutrino oscillation data, lepton flavor violating processes, N{sub 1} can have a relic density in agreement with the recent Planck data, and the electroweak phase transition can be strongly first order. We also show that the charged scalars may enhance the branching ratio h???, where as h??Z get can get few percent suppression. We also discuss the phenomenological implications of the RH neutrinos at the collider.
Neutrino-2008: Where are we? Where are we going?
Smirnov, Alexei Yu
2008-01-01T23:59:59.000Z
Our present knowledge of neutrinos can be summarized in terms of the "standard neutrino scenario". Phenomenology of this scenario as well as attempts to uncover physics behind neutrino mass and mixing are described. Goals of future studies include complete reconstruction of the neutrino mass and flavor spectrum, further test of the standard scenario and search for new physics beyond it. Developments of new experimental techniques may lead to construction of new neutrino detectors from table-top to multi-Megaton scales which will open new horizons in the field. With detection of neutrino bursts from the Galactic supernova and high energy cosmic neutrinos neutrino astrophysics will enter qualitatively new phase. Neutrinos and LHC (and future colliders), neutrino astronomy, neutrino structure of the Universe, and probably, neutrino technologies will be among leading topics of research.
Neutrino-2008: Where are we? Where are we going?
Alexei Yu. Smirnov
2008-10-15T23:59:59.000Z
Our present knowledge of neutrinos can be summarized in terms of the "standard neutrino scenario". Phenomenology of this scenario as well as attempts to uncover physics behind neutrino mass and mixing are described. Goals of future studies include complete reconstruction of the neutrino mass and flavor spectrum, further test of the standard scenario and search for new physics beyond it. Developments of new experimental techniques may lead to construction of new neutrino detectors from table-top to multi-Megaton scales which will open new horizons in the field. With detection of neutrino bursts from the Galactic supernova and high energy cosmic neutrinos neutrino astrophysics will enter qualitatively new phase. Neutrinos and LHC (and future colliders), neutrino astronomy, neutrino structure of the Universe, and probably, neutrino technologies will be among leading topics of research.
Parke, Stephen J.; /Fermilab
2011-07-01T23:59:59.000Z
Starting in the late 1960s, neutrino detectors began to see signs that neutrinos, now known to come in the flavors electron ({nu}{sub e}), muon ({nu}{sub {mu}}), and tau ({nu}{sub {tau}}), could transform from one flavor to another. The findings implied that neutrinos must have mass, since massless particles travel at the speed of light and their clocks, so to speak, don't tick, thus they cannot change. What has since been discovered is that neutrinos oscillate at two distinct scales, 500 km/GeV and 15,000 km/GeV, which are defined by the baseline (L) of the experiment (the distance the neutrino travels) divided by the neutrino energy (E). Neutrinos of one flavor can oscillate into neutrinos of another flavor at both L/E scales, but the amplitude of these oscillations is different for the two scales and depends on the initial and final flavor of the neutrinos. The neutrino states that propogate unchanged in time, the mass eigenstates {nu}1, {nu}2, {nu}3, are quantum mechanical mixtures of the electron, muon, and tau neutrino flavors, and the fraction of each flavor in a given mass eigenstate is controlled by three mixing angles and a complex phase. Two of these mixing angles are known with reasonable precision. An upper bound exists for the third angle, called {theta}{sub 13}, which controls the size of the muon neutrino to electron neutrino oscillation at an L/E of 500 km/GeV. The phase is completely unknown. The existence of this phase has important implications for the asymmetry between matter and antimatter we observe in the universe today. Experiments around the world have steadily assembled this picture of neutrino oscillation, but evidence of muon neutrino to electron neutrino oscillation at 500 km/GeV has remained elusive. Now, a paper from the T2K (Tokai to Kamioka) experiment in Japan, reports the first possible observation of muon neutrinos oscillating into electron neutrinos at 500 km/GeV. They see 6 candidate signal events, above an expected background of 1.5 events. The probability that the 6 events are all background is only about 0.7%. Stated differently, this is a 2.7{sigma} indication that the parameter that controls the oscillation, the neutrino mixing angle {theta}{sub 13}, is nonzero, just shy of the 3{sigma} requirement to claim 'evidence for.' Nevertheless, this experiment provides the strongest indication to date that this oscillation actually occurs in nature.
Constraining Sterile Neutrinos Using Reactor Neutrino Experiments
Ivan Girardi; Davide Meloni; Tommy Ohlsson; He Zhang; Shun Zhou
2014-08-21T23:59:59.000Z
Models of neutrino mixing involving one or more sterile neutrinos have resurrected their importance in the light of recent cosmological data. In this case, reactor antineutrino experiments offer an ideal place to look for signatures of sterile neutrinos due to their impact on neutrino flavor transitions. In this work, we show that the high-precision data of the Daya Bay experi\\-ment constrain the 3+1 neutrino scenario imposing upper bounds on the relevant active-sterile mixing angle $\\sin^2 2 \\theta_{14} \\lesssim 0.06$ at 3$\\sigma$ confidence level for the mass-squared difference $\\Delta m^2_{41}$ in the range $(10^{-3},10^{-1}) \\, {\\rm eV^2}$. The latter bound can be improved by six years of running of the JUNO experiment, $\\sin^22\\theta_{14} \\lesssim 0.016$, although in the smaller mass range $ \\Delta m^2_{41} \\in (10^{-4} ,10^{-3}) \\, {\\rm eV}^2$. We have also investigated the impact of sterile neutrinos on precision measurements of the standard neutrino oscillation parameters $\\theta_{13}$ and $\\Delta m^2_{31}$ (at Daya Bay and JUNO), $\\theta_{12}$ and $\\Delta m^2_{21}$ (at JUNO), and most importantly, the neutrino mass hierarchy (at JUNO). We find that, except for the obvious situation where $\\Delta m^2_{41}\\sim \\Delta m^2_{31}$, sterile states do not affect these measurements substantially.
H. Nunokawa; W. J. C. Teves; R. Zukanovich Funchal
2002-10-10T23:59:59.000Z
Assuming that neutrinos are Majorana particles, in a three generation framework, current and future neutrino oscillation experiments can determine six out of the nine parameters which fully describe the structure of the neutrino mass matrix. We try to clarify the interplay among the remaining parameters, the absolute neutrino mass scale and two CP violating Majorana phases, and how they can be accessed by future neutrinoless double beta ($0\
Neutrinos Are Nearly Dirac Fermions
Kevin Cahill
2000-06-10T23:59:59.000Z
Neutrino masses and mixings are analyzed in terms of left-handed fields and a 6x6 complex symmetric mass matrix whose singular values are the neutrino masses. An angle x_nu characterizes the kind of the neutrinos, with x_nu = 0 for Dirac neutrinos and x_nu = pi/2 for Majorana neutrinos. If x_nu = 0, then baryon-minus-lepton number is conserved. When x_nu is approximately zero, the six neutrino masses coalesce into three nearly degenerate pairs. Thus the smallness of the differences in neutrino masses exhibited in the solar and atmospheric neutrino experiments and the stringent limits on neutrinoless double beta decay are naturally explained if B-L is approximately conserved and neutrinos are nearly Dirac fermions. If one sets sin(x_nu) = 0.003, suppresses inter-generational mixing, and imposes a quark-like mass hierarchy, then one may fit the essential features of the solar, reactor, and atmospheric neutrino experiments with otherwise random mass matrices in the eV range. This B-L model leads to these predictions: neutrinos oscillate mainly between flavor eigenfields and sterile eigenfields, and so the probabilities of the appearance of neutrinos or antineutrinos are very small; neutrinos may well be of cosmological importance; in principle the disappearance of the tau neutrino should be observable; and neutrinoless double beta decay is suppressed by an extra factor of < 10^(-5) and hence will not be seen in the Heidelberg/Moscow, IGEX, GENIUS, or CUORE experiments.
Fermion masses and mixings from dihedral flavor symmetries with preserved subgroups
Blum, A.; Hagedorn, C.; Lindner, M. [Max-Planck-Institut fuer Kernphysik, Postfach 10 39 80, 69029 Heidelberg (Germany)
2008-04-01T23:59:59.000Z
We perform a systematic study of dihedral groups used as flavor symmetry. The key feature here is the fact that we do not allow the dihedral groups to be broken in an arbitrary way, but in all cases some (nontrivial) subgroup has to be preserved. In this way we arrive at only five possible (Dirac) mass matrix structures which can arise, if we require that the matrix has to have a nonvanishing determinant and that at least two of the three generations of left-handed (conjugate) fermions are placed into an irreducible two-dimensional representation of the flavor group. We show that there is no difference between the mass matrix structures for single- and double-valued dihedral groups. Furthermore, we comment on possible forms of Majorana mass matrices. As a first application we find a way to express the Cabibbo angle, i.e. the Cabibbo-Kobayashi-Maskawa matrix element |V{sub us}|, in terms of group theory quantities only, the group index n, the representation index j and the index m{sub u,d} of the different preserved subgroups in the up and down quark sector: |V{sub us}|=|cos(({pi}(m{sub u}-m{sub d})j/n))| which is |cos((3{pi}/7))|{approx_equal}0.2225 for n=7, j=1, m{sub u}=3 and m{sub d}=0. We prove that two successful models which lead to maximal atmospheric mixing and vanishing {theta}{sub 13} in the lepton sector are based on the fact that the flavor symmetry is broken in the charged lepton, Dirac neutrino and Majorana neutrino sector down to different preserved subgroups whose mismatch results in the prediction of these mixing angles. This also demonstrates the power of preserved subgroups in connection with the prediction of mixing angles in the quark as well as in the lepton sector.
Sterile neutrino oscillations in core-collapse supernova simulations
Warren, MacKenzie L; Mathews, Grant; Hidaka, Jun; Kajino, Toshitaka
2014-01-01T23:59:59.000Z
We have made core-collapse supernova simulations that allow oscillations between electron neutrinos (or their anti particles) with right-handed sterile neutrinos. We have considered a range of mixing angles and sterile neutrino masses including those consistent with sterile neutrinos as a dark matter candidate. We examine whether such oscillations can impact the core bounce and shock reheating in supernovae. We identify the optimum ranges of mixing angles and masses that can dramatically enhance the supernova explosion by efficiently transporting electron anti-neutrinos from the core to behind the shock where they provide additional heating leading to much larger explosion kinetic energies. We show that an interesting oscillation in the neutrino luminosity develops due to a cycle of depletion of the neutrino density by conversion to sterile neutrinos that shuts off the conversion, followed by a replenished neutrino density as neutrinos transport through the core.
H. Nunokawa
2001-05-03T23:59:59.000Z
In this talk, I review, from the phenomenological point of view, solutions to the solar neutrino problem, which are not provided by the conventional neutrino oscillation induced by mass and flavor mixing, and show that they can provide a good fit to the observed data. I also consider some simple implications for low energy solar neutrino experiments.
The Power of Neutrino Mass Sum Rules for Neutrinoless Double Beta Decay Experiments
Stephen F. King; Alexander Merle; Alexander J. Stuart
2013-07-31T23:59:59.000Z
Neutrino mass sum rules relate the three neutrino masses within generic classes of flavour models, leading to restrictions on the effective mass parameter measured in experiments on neutrinoless double beta decay as a function of the lightest neutrino mass. We perform a comprehensive study of the implications of such neutrino mass sum rules, which provide a link between model building, phenomenology, and experiments. After a careful explanation of how to derive predictions from sum rules, we discuss a large number of examples both numerically, using all three global fits available for the neutrino oscillation data, and analytically wherever possible. In some cases, our results disagree with some of those in the literature for reasons that we explain. Finally we discuss the experimental prospects for many current and near-future experiments, with a particular focus on the uncertainties induced by the unknown nuclear physics involved. We find that, in many cases, the power of the neutrino mass sum rules is so strong as to allow certain classes of models to be tested by the next generation of neutrinoless double beta decay experiments. Our study can serve as both a guideline and a theoretical motivation for future experimental studies.
Neutrino Physics: A Selective Overview
Scott M. Oser
2006-04-11T23:59:59.000Z
Neutrinos in the Standard Model of particle physics are massless, neutral fermions that seemingly do little more than conserve 4-momentum, angular momentum, lepton number, and lepton flavour in weak interactions. In the last decade conclusive evidence has demonstrated that the Standard Model's description of neutrinos does not match reality. We now know that neutrinos undergo flavour oscillations, violating lepton flavour conservation and implying that neutrinos have non-zero mass. A rich oscillation phenomenology then becomes possible, including matter-enhanced oscillation and possibly CP violation in the neutrino sector. Extending the Standard Model to include neutrino masses requires the addition of new fields and mass terms, and possibly new methods of mass generation. In this review article I will discuss the evidence that has established the existence of neutrino oscillation, and then highlight unresolved issues in neutrino physics, such as the nature of three-generational mixing (including CP-violating effects), the origins of neutrino mass, the possible existence of light sterile neutrinos, and the difficult question of measuring the absolute mass scale of neutrinos.
Results on neutrino mass and mixing from Super Kamiokande
Kielczewska, Danuta; Super Kamiokande Collaboration, .; K2K Collaboration, .
2002-01-01T23:59:59.000Z
and expeted events in Super Kamiokande. Events observed FCtrak muons measured in Super Kamiokande detetor. The solid
Ram Lal Awasthi; M. K. Parida; Sudhanwa Patra
2013-01-21T23:59:59.000Z
In the inverse seesaw extension of the standard model, supersymmetric or non-supersymmetric, while the light left-handed neutrinos are Majorana, the heavy right-handed neutrinos are pseudo-Dirac fermions. We show how one of these latter category of particles can contribute quite significantly to neutrinoless double beta decay. The neutrino virtuality momentum is found to play a crucial role in the non-standard contributions leading to the prediction of the pseudo-Dirac fermion mass in the range of $120\\, {MeV}-500\\, {MeV}$. When the Dirac neutrino mass matrix in the inverse seesaw formula is similar to the up-quark mass matrix, characteristic of high scale quark-lepton symmetric origin, the predicted branching ratios for lepton flavor violating decays are also found to be closer to the accessible range of ongoing experiments.
G. L. Fogli; E. Lisi; A. Marrone; A. Melchiorri; A. Palazzo; P. Serra; J. Silk; A. Slosar
2006-08-04T23:59:59.000Z
In the light of recent neutrino oscillation and non-oscillation data, we revisit the phenomenological constraints applicable to three observables sensitive to absolute neutrino masses: The effective neutrino mass in single beta decay (m_beta); the effective Majorana neutrino mass in neutrinoless double beta decay (m_2beta); and the sum of neutrino masses in cosmology (Sigma). In particular, we include the constraints coming from the first Main Injector Neutrino Oscillation Search (MINOS) data and from the Wilkinson Microwave Anisotropy Probe (WMAP) three-year (3y) data, as well as other relevant cosmological data and priors. We find that the largest neutrino squared mass difference is determined with a 15% accuracy (at 2-sigma) after adding MINOS to world data. We also find upper bounds on the sum of neutrino masses Sigma ranging from ~2 eV (WMAP-3y data only) to ~0.2 eV (all cosmological data) at 2-sigma, in agreement with previous studies. In addition, we discuss the connection of such bounds with those placed on the matter power spectrum normalization parameter sigma_8. We show how the partial degeneracy between Sigma and sigma_8 in WMAP-3y data is broken by adding further cosmological data, and how the overall preference of such data for relatively high values of sigma_8 pushes the upper bound of Sigma in the sub-eV range. Finally, for various combination of data sets, we revisit the (in)compatibility between current Sigma and m_2beta constraints (and claims), and derive quantitative predictions for future single and double beta decay experiments.
A field-theoretical approach to entanglement in neutrino mixing and oscillations
M. Blasone; F. Dell'Anno; S. De Siena; F. Illuminati
2014-06-04T23:59:59.000Z
The phenomena of particle mixing and flavor oscillations in elementary particle physics can be addressed by the point of view of quantum information theory, and described in terms of multi-mode entanglement of single-particle states. In this paper we show that such a description can be extended to the domain of quantum field theory, where we uncover a fine structure of quantum correlations associated with multi-mode, multi-particle entanglement. By means of an entanglement measure based on the linear entropies associated with all the possible bipartitions, we analyze the entanglement in the states of flavor neutrinos and anti-neutrinos. Remarkably, we show that the entanglement is connected with experimentally measurable quantities, i.e. the variances of the lepton numbers and charges.
Neutrino 2012: Outlook - theory
A. Yu. Smirnov
2012-10-15T23:59:59.000Z
Ongoing developments in theory and phenomenology are related to the measured large value of 1-3 mixing and indications of significant deviation of the 2-3 mixing from maximal one. "Race" for the mass hierarchy has started and there is good chance that multi-megaton scale atmospheric neutrino detectors with low threshold (e.g. PINGU) will establish the type of hierarchy. Two IceCube candidates of the PeV cosmic neutrinos if confirmed, is the beginning of new era of high energy neutrino astronomy. Accumulation of data on solar neutrinos (energy spectrum, D-N asymmetry, value of $\\Delta m^2_{21}$) may uncover some new physics. The Tri-bimaximal mixing is disfavored and the existing discrete symmetry paradigm may change. The confirmed QLC prediction, $\\theta_{13} \\approx \\theta_{C}/\\sqrt{2}$, testifies for GUT, seesaw and some symmetry at very high scales. However, the same value of 1-3 mixing can be obtained in various ways which have different implications. The situation in lepton sector changes from special (with specific neutrino symmetries, etc.) to normal, closer to that in the quark sector. Sterile neutrinos are challenge for neutrino physics but also opportunity with many interesting phenomenological consequences. Further studies of possible connections between neutrinos and the dark sector of the Universe may lead to breakthrough both in particle physics and cosmology.
Neutrino mass, lepton number, and the origin of matter
antiparticles? And many other things% Do neutrinos violate CP? #12;Neutrinoless Double Beta Decay W. Rodejohann? #12;Neutrinoless Double Beta Decay 1 sigma W. Rodejohann, 1206.2560 #12;14 F. Iachello #12;15 Regions
Solar models and solar neutrino oscillations John N Bahcall and Carlos Pea-Garay
Bahcall, John
Solar models and solar neutrino oscillations John N Bahcall and Carlos Peńa-Garay Institute and experimental, of solar neutrino fluxes and of the masses and mixing angles that characterize solar neutrino oscillations. We also summarize the principal reasons for performing new solar neutrino experiments and what we
Solar models and solar neutrino oscillations John N Bahcall and Carlos PeaGaray
Bahcall, John
Solar models and solar neutrino oscillations John N Bahcall and Carlos PeńaGaray Institute and experimental, of solar neutrino fluxes and of the masses and mixing angles that characterize solar neutrino oscillations. We also summarize the principal reasons for performing new solar neutrino experiments and what we
Kayser, Boris
2012-06-01T23:59:59.000Z
To complement the neutrino-physics lectures given at the 2011 International School on Astro Particle Physics devoted to Neutrino Physics and Astrophysics (ISAPP 2011; Varenna, Italy), at the 2011 European School of High Energy Physics (ESHEP 2011; Cheila Gradistei, Romania), and, in modified form, at other summer schools, we present here a written description of the physics of neutrino oscillation. This description is centered on a new way of deriving the oscillation probability. We also provide a brief guide to references relevant to topics other than neutrino oscillation that were covered in the lectures. Neutrinos and photons are by far the most abundant elementary particles in the universe. Thus, if we would like to comprehend the universe, we must understand the neutrinos. Of course, studying the neutrinos is challenging, since the only known forces through which these electrically-neutral leptons interact are the weak force and gravity. Consequently, interactions of neutrinos in a detector are very rare events, so that very large detectors and intense neutrino sources are needed to make experiments feasible. Nevertheless, we have confirmed that the weak interactions of neutrinos are correctly described by the Standard Model (SM) of elementary particle physics. Moreover, in the last 14 years, we have discovered that neutrinos have nonzero masses, and that leptons mix. These discoveries have been based on the observation that neutrinos can change from one 'flavor' to another - the phenomenon known as neutrino oscillation. We shall explain the physics of neutrino oscillation, deriving the probability of oscillation in a new way. We shall also provide a very brief guide to references that can be used to study some major neutrino-physics topics other than neutrino oscillation.
Lindner, Manfred; Merle, Alexander; Rodejohann, Werner [Physik-Department, Technische Universitaet Muenchen, James-Franck-Strasse, D-85748 Garching (Germany)
2006-03-01T23:59:59.000Z
We analyze the impact of a measurement, or of an improved bound, on {theta}{sub 13} for the determination of the effective neutrino mass in neutrinoless double beta decay and cosmology. In particular, we discuss how an improved limit on (or a specific value of) {theta}{sub 13} can influence the determination of the neutrino mass spectrum via neutrinoless double beta decay. We also discuss the interplay with improved cosmological neutrino mass searches.
Recent Results in Neutrino Physics
K. V. L. Sarma
1994-11-07T23:59:59.000Z
This is a survey of the current experimental information on some of the interesting issues in neutrino physics: neutrino species, neutrino masses, neutrino magnetic moments, solar neutrinos, and the atmospheric neutrino anomaly.
Kaur, Daljeet; Kumar, Sanjeev
2014-01-01T23:59:59.000Z
The India-based Neutrino Observatory (INO) will host a 50 kt magnetized iron calorimeter (ICAL) detector that will be able to detect muon tracks and hadron showers produced by Charged-Current muon neutrino interactions in the detector. The ICAL experiment will be able to determine the precision of atmospheric neutrino mixing parameters and neutrino mass hierarchy using atmospheric muon neutrinos through earth matter effect. In this paper, we report on the sensitivity for the atmospheric neutrino mixing parameters ($\\sin^{2}\\theta_{23}$ and $|\\Delta m^{2}_{32}|$) for the ICAL detector using the reconstructed neutrino energy and muon direction as observables. We apply realistic resolutions and efficiencies obtained by the ICAL collaboration with a GEANT4-based simulation to reconstruct neutrino energy and muon direction. Our study shows that using neutrino energy and muon direction as observables for a $\\chi^{2}$ analysis, ICAL detector can measure $\\sin^{2}\\theta_{23}$ and $|\\Delta m^{2}_{32}|$ with 13% and 4%...
EFFECTS OF THE NEUTRINO MASS SPLITTING ON THE NONLINEAR MATTER POWER SPECTRUM
Wagner, Christian; Verde, Licia; Jimenez, Raul [Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E08028 Barcelona (Spain)
2012-06-20T23:59:59.000Z
We have performed cosmological N-body simulations which include the effect of the masses of the individual neutrino species. The simulations were aimed at studying the effect of different neutrino hierarchies on the matter power spectrum. Compared to the linear theory predictions, we find that nonlinearities enhance the effect of hierarchy on the matter power spectrum at mildly nonlinear scales. The maximum difference between the different hierarchies is about 0.5% for a sum of neutrino masses of 0.1 eV. Albeit this is a small effect, it is potentially measurable from upcoming surveys. In combination with neutrinoless double-{beta} decay experiments, this opens up the possibility of using the sky to determine if neutrinos are Majorana or Dirac fermions.
Tritium beta decay, neutrino mass matrices, and interactions beyond the standard model
Stephenson, G. J.; Goldman, T.; McKellar, B. H. J.
2000-11-01T23:59:59.000Z
The interference of charge changing interactions, weaker than the V-A standard model (SM) interaction and having a different Lorentz structure, with that SM interaction, can, in principle, produce effects near the end point of the tritium beta decay spectrum which are of a different character from those produced by the purely kinematic effect of neutrino mass expected in the simplest extension of the SM. We show that the existence of more than one mass eigenstate can lead to interference effects at the end point that are stronger than those occurring over the entire spectrum. We discuss these effects both for the special case of Dirac neutrinos and the more general case of Majorana neutrinos and show that, for the present precision of the experiments, one formula should suffice to express the interference effects in all cases. Implications for ''sterile'' neutrinos are noted.
Dark Matter and Lepton Flavour Violation in a Hybrid Neutrino Mass Model
Deppisch, Frank F
2014-01-01T23:59:59.000Z
We describe a hybrid model in which the light neutrino mass matrix receives both tree-level seesaw and loop-induced contributions. An additional U(1) gauge symmetry is used to stabilize the lightest right-handed neutrino as the Dark Matter candidate. After fitting the experimental neutrino data, we analyze and correlate the phenomenological consequences of the model, namely its impact on electroweak precision measurements, the Dark Matter relic abundance, lepton flavour violating rare decays and neutrinoless double beta decay. We find that natural realizations of the model characterized by large Yukawa couplings are compatible with and close to the current experimental limits.
Neutrino masses in SU(4){sub L}?U(1){sub X} gauge models
Palcu, Adrian [Faculty of Exact Sciences - Aurel Vlaicu University Arad, Str. Elena Dr?goi 2, Arad - 310330 (Romania)
2013-11-13T23:59:59.000Z
Neutrino masses are obtained within SU(4){sub L}?U(1){sub X} electroweak gauge models with spontaneous symmetry breaking by simply exploiting the tree level realization of certain dimension-five effective operators. The scalar sector needs not to be enlarged, since these operators are constructed as direct products among scalar multiplets already existing in the model. There is a unique generic matrix for Yukawa couplings in the neutrino sector, while the charged leptons are already in their diagonal basis. The experimentally observed phenomenology in the neutrino sector is obtained as a natural consequence of this particular approach.
Neutrino Physics: Status and Prospects
K. Scholberg
2003-08-05T23:59:59.000Z
This pedagogical overview will cover the current status of neutrino physics from an experimentalist's point of view, focusing primarily on oscillation studies. The evidence for neutrino oscillations will be presented, along with the prospects for further refinement of observations in each of the indicated regions of two-flavor oscillation parameter space. The next steps in oscillation physics will then be covered (under the assumption of three-flavor mixing): the quest for $\\theta_{13}$, mass hierarchy and, eventually, leptonic CP violation. Prospects for non-oscillation aspects of neutrino physics, such as kinematic tests for absolute neutrino mass and double beta decay searches, will also be discussed briefly.
Cold Dark Matter, Radiative Neutrino Mass, mu to e gamma, and Neutrinoless Double Beta Decay
Jisuke Kubo; Ernest Ma; Daijiro Suematsu
2006-08-24T23:59:59.000Z
Two of the most important and pressing questions in cosmology and particle physics are: (1) What is the nature of cold dark matter? and (2) Will near-future experiments on neutrinoless double beta decay be able to ascertain that the neutrino is a Majorana particle, i.e. its own antiparticle? We show that these two seemingly unrelated issues are intimately connected if neutrinos acquire mass only because of their interactions with dark matter.
Nuclear structure aspects of neutrinoless {beta}{beta} decay: limits on the electron neutrino mass
Civitarese, O. [Department of Physics. University of La Plata, 1900 La Plata (Argentina); Suhonen, J. [Department of Physics. University of Jyvaeskyla, (Finland)
2007-02-12T23:59:59.000Z
We discuss some features of the nuclear structure elements participant in the calculation of the mass sector of the half-life of the neutrinoless double beta decay, and the consequences upon the adopted limits of the electron-neutrino mass.
2010-01-01T23:59:59.000Z
accelerator experiments.Events (observed/expected) from accelerator experiments. Some neutrino oscillation for the 2012 edition (URL: http://pdg.lbl.gov) Neutrino Mixing A REVIEW GOES HERE Check our WWW List of Reviews (A) Neutrino fluxes and event ratios(A) Neutrino fluxes and event ratios(A) Neutrino fluxes
Neutrino mixing matrices with relatively large $?_{13}$ and with texture one-zero
K. N. Deepthi; Srinu Gollu; R. Mohanta
2012-02-04T23:59:59.000Z
The recent T2K, MINOS and Double Chooz oscillation data hint a relatively large $\\theta_{13}$, which can be accommodated by some general modification of the Tribimaximal/Bimaximal/Democratic mixing matrices. Using such matrices we analyze several Majorana mass matrices with texture one-zero and show whether they satisfy normal or inverted mass hierarchy and phenomenologically viable or not.
Neutrino mixing matrices with relatively large $\\theta_{13}$ and with texture one-zero
Deepthi, K N; Mohanta, R
2011-01-01T23:59:59.000Z
The recent T2K, MINOS and Double Chooz oscillation data hint a relatively large $\\theta_{13}$, which can be accommodated by some general modification of the Tribimaximal/Bimaximal/Democratic mixing matrices. Using such matrices we analyze several Majorana mass matrices with texture one-zero and show whether they satisfy normal or inverted mass hierarchy and phenomenologically viable or not.
The Neutrinoless Double Beta Decay, Physics beyond the Standard Model and the Neutrino Mass
Amand Faessler
2012-03-16T23:59:59.000Z
The Neutrinoless double beta Decay allows to determine the effectice Majorana electron neutrino mass. For this the following conditions have to be satisfied: (i) The neutrino must be a Majorana particle, i. e. identical to the antiparticle. (ii) The half life has to be measured. (iii)The transition matrix element must be reliably calculated. (iv) The leading mechanism must be the light Majorana neutrino exchange. The present contribution studies the accuracy with which one can calculate by different methods: (1) Quasi-Particle Random Phase Approach (QRPA), (2) the Shell Model (SM), (3) the (before the variation) angular momentum projected Hartree-Fock-Bogoliubov method (PHFB)and the (4) Interacting Boson Approach (IBA). In the second part we investigate how to determine experimentally the leading mechanism for the Neutrinoless Double Beta Decay. Is it (a) the light Majorana neutrino exchange as one assumes to determine the effective Majorana neutrino mass, ist it the heavy left (b) or right handed (c) Majorana neutrino exchange allowed by left-right symmetric Grand Unified Theories (GUT's). Is it a mechanism due to Supersymmetry e.g. with gluino exchange and R-parity and lepton number violating terms. At the end we assume, that Klapdor et al. have indeed measured the Neutrinoless Double Beta Decay(, although contested,)and that the light Majorana neutrino exchange is the leading mechanism. With our matrix elements we obtain then an effective Majorana neutrino mass of: = 0.24 [eV], exp (pm) 0.02; theor. (pm) 0.01 [eV
Lopez-Pavon, J; Petcov, S T
2015-01-01T23:59:59.000Z
We perform a detailed analysis of the one-loop corrections to the light neutrino mass matrix within low scale type I seesaw extensions of the Standard Model and their implications in experimental searches for neutrinoless double beta decay. We show that a sizable contribution to the effective Majorana neutrino mass from the exchange of heavy Majorana neutrinos is always possible, provided one requires a fine-tuned cancellation between the tree-level and one-loop contribution to the light neutrino masses. We quantify the level of fine-tuning as a function of the seesaw parameters and introduce a generalisation of the Casas-Ibarra parametrization of the neutrino Yukawa matrix, which easily allows to include the one-loop corrections to the light neutrino masses.
Physics with a Neutrino Superbeam Kirk T. McDonald
McDonald, Kirk
Neutrinos could have a small mass (Pauli, Fermi, Majorana, 1930's). Massive neutrinos can mix (PontecorvoPhysics with a Neutrino Superbeam Kirk T. McDonald Princeton U. mcdonald@puphep.princeton.edu Physics Colloquium at Brookhaven National Laboratory November 27, 2001 http://puhep1.princeton
Dighe, Amol; Ray, Shamayita [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Goswami, Srubabati [Physical Research Laboratory, Navrangpura, Ahmedabad 380009 (India)
2009-04-01T23:59:59.000Z
Renormalization group (RG) evolution of the neutrino mass matrix may take the value of the mixing angle {theta}{sub 13} very close to zero, or make it vanish. On the other hand, starting from {theta}{sub 13}=0 at the high scale it may be possible to generate a nonzero {theta}{sub 13}, radiatively. In the most general scenario with nonvanishing CP violating Dirac and Majorana phases, we explore the evolution in the vicinity of {theta}{sub 13}=0, in terms of its structure in the complex U{sub e3} plane. This allows us to explain the apparent singularity in the evolution of the Dirac CP phase {delta} at {theta}{sub 13}=0. We also introduce a formalism for calculating the RG evolution of neutrino parameters that uses the Jarlskog invariant and naturally avoids this singular behavior. We find that the parameters need to be extremely fine-tuned in order to get exactly vanishing {theta}{sub 13} during evolution. For the class of neutrino mass models with {theta}{sub 13}=0 at the high scale, we calculate the extent to which RG evolution can generate a nonzero {theta}{sub 13}, when the low energy effective theory is the standard model or its minimal supersymmetric extension. We find correlated constraints on {theta}{sub 13}, the lightest neutrino mass m{sub 0}, the effective Majorana mass m{sub ee} measured in the neutrinoless double beta decay, and the supersymmetric parameter tan{beta}.
Anti-Neutrino Imprint in Solar Neutrino Flare
D. Fargion
2006-06-09T23:59:59.000Z
Future neutrino detector at Megaton mass might enlarge the neutrino telescope thresholds revealing cosmic supernova background and largest solar flares neutrino. Indeed the solar energetic flare particles while scattering among themselves on Solar corona atmosphere must produce prompt charged pions, whose chain decays are source of solar (electron-muon) neutrino "flare" (at tens or hundreds MeV energy). These brief (minutes) neutrino "burst" at largest flare peak may overcome by three to five order of magnitude the steady atmospheric neutrino noise on the Earth, possibly leading to their detection above detection. Moreover the birth of anti-neutrinos at a few tens MeVs is well loudly flaring above a null thermal "hep" anti-neutrino solar background and also above a tiny supernova relic and atmospheric noise. The largest prompt solar anti-neutrino "burst" may be well detected in future SuperKamikande (Gadolinium implemented) by anti-neutrino signatures mostly in inverse Beta decay. Our estimate for the recent and exceptional October - November 2003 solar flares and January 20th 2005 exceptional eruption might lead to a few events above or near unity for existing Super-Kamiokande and above unity for Megaton detectors. The neutrino spectra may reflect in a subtle way the neutrino flavor oscillations and mixing in flight. A comparison of the solar neutrino flare (at their birth place on Sun and after oscillation on the arrival on the Earth) with other neutrino foreground is estimated: it offers an independent track to disentangle the neutrino flavor puzzles and its most secret mixing angles. The sharpest noise-free anti-neutrino imprint maybe its first clean voice.
Gil-Botella, I
2013-01-01T23:59:59.000Z
The fundamental properties of neutrinos are reviewed in these lectures. The first part is focused on the basic characteristics of neutrinos in the Standard Model and how neutrinos are detected. Neutrino masses and oscillations are introduced and a summary of the most important experimental results on neutrino oscillations to date is provided. Then, present and future experimental proposals are discussed, including new precision reactor and accelerator experiments. Finally, different approaches for measuring the neutrino mass and the nature (Majorana or Dirac) of neutrinos are reviewed. The detection of neutrinos from supernovae explosions and the information that this measurement can provide are also summarized at the end.
Proton Hexality from an Anomalous Flavor U(1) and Neutrino Masses - Linking to the String Scale
Herbi K. Dreiner; Christoph Luhn; Hitoshi Murayama; Marc Thormeier
2007-12-06T23:59:59.000Z
We devise minimalistic gauged U(1)_X Froggatt-Nielsen models which at low-energy give rise to the recently suggested discrete gauge Z_6 symmetry, proton hexality, thus stabilizing the proton. Assuming three generations of right-handed neutrinos, with the proper choice of X-charges, we obtain viable neutrino masses. Furthermore, we find scenarios such that no X-charged hidden sector superfields are needed, which from a bottom-up perspective allows the calculation of g_string, g_X and G_SM's Kac-Moody levels. The only mass scale apart from M_grav is m_soft.
0+ -> 2+ neutrinoless double beta decay triggered directly by the Majorana neutrino mass
T. Tomoda
1999-09-12T23:59:59.000Z
We treat 0+ -> 2+ neutrinoless double beta decays taking into account recoil corrections to the nuclear currents. The decay probability can be written as a quadratic form of the effective coupling constants of the right-handed leptonic currents and the effective neutrino mass. We calculate the nuclear matrix elements for the 0+ -> 2+ neutrinoless double beta decays of 76Ge and 100Mo, and demonstrate that the relative sensitivities of 0+ -> 2+ decays to the neutrino mass and the right-handed currents are comparable to those of 0+ -> 0+ decays.
D. Franco; C. Jollet; A. Kouchner; V. Kulikovskiy; A. Meregaglia; S. Perasso; T. Pradier; A. Tonazzo; V. Van Elewyck
2013-03-14T23:59:59.000Z
Large mass ice/water Cherenkov experiments, optimized to detect low energy (1-20 GeV) atmospheric neutrinos, have the potential to discriminate between normal and inverted neutrino mass hierarchies. The sensitivity depends on several model and detector parameters, such as the neutrino flux profile and normalization, the Earth density profile, the oscillation parameter uncertainties, and the detector effective mass and resolution. A proper evaluation of the mass hierarchy discrimination power requires a robust statistical approach. In this work, the Toy Monte Carlo, based on an extended unbinned likelihood ratio test statistic, was used. The effect of each model and detector parameter, as well as the required detector exposure, was then studied. While uncertainties on the Earth density and atmospheric neutrino flux profiles were found to have a minor impact on the mass hierarchy discrimination, the flux normalization, as well as some of the oscillation parameter (\\Delta m^2_{31}, \\theta_{13}, \\theta_{23}, and \\delta_{CP}) uncertainties and correlations resulted critical. Finally, the minimum required detector exposure, the optimization of the low energy threshold, and the detector resolutions were also investigated.
Light Sterile Neutrinos and Short Baseline Neutrino Oscillation Anomalies
JiJi Fan; Paul Langacker
2012-01-31T23:59:59.000Z
We study two possible explanations for short baseline neutrino oscillation anomalies, such as the LSND and MiniBooNE anti-neutrino data, and for the reactor anomaly. The first scenario is the mini-seesaw mechanism with two eV-scale sterile neutrinos. We present both analytic formulas and numerical results showing that this scenario could account for the short baseline and reactor anomalies and is consistent with the observed masses and mixings of the three active neutrinos. We also show that this scenario could arise naturally from an effective theory containing a TeV-scale VEV, which could be related to other TeV-scale physics. The minimal version of the mini-seesaw relates the active-sterile mixings to five real parameters and favors an inverted hierarchy. It has the interesting property that the effective Majorana mass for neutrinoless double beta decay vanishes, while the effective masses relevant to tritium beta decay and to cosmology are respectively around 0.2 and 2.4 eV. The second scenario contains only one eV-scale sterile neutrino but with an effective non-unitary mixing matrix between the light sterile and active neutrinos. We find that though this may explain the anomalies, if the non-unitarity originates from a heavy sterile neutrino with a large (fine-tuned) mixing angle, this scenario is highly constrained by cosmological and laboratory observations.
Pseudo-Dirac Neutrinos, a Challenge for Neutrino Telescopes
John F. Beacom; Nicole F. Bell; Dan Hooper; John G. Learned; Sandip Pakvasa; Thomas J. Weiler
2004-01-05T23:59:59.000Z
Neutrinos may be pseudo-Dirac states, such that each generation is actually composed of two maximally-mixed Majorana neutrinos separated by a tiny mass difference. The usual active neutrino oscillation phenomenology would be unaltered if the pseudo-Dirac splittings are $\\delta m^2 \\alt 10^{-12}$ eV$^2$; in addition, neutrinoless double beta decay would be highly suppressed. However, it may be possible to distinguish pseudo-Dirac from Dirac neutrinos using high-energy astrophysical neutrinos. By measuring flavor ratios as a function of $L/E$, mass-squared differences down to $\\delta m^2 \\sim 10^{-18}$ eV$^2$ can be reached. We comment on the possibility of probing cosmological parameters with neutrinos.
KATRIN: an experiment to determine the neutrino mass from the beta decay of tritium
R. G. Hamish Robertson
2013-07-21T23:59:59.000Z
KATRIN is a very large scale tritium-beta-decay experiment to determine the mass of the neutrino. It is presently under construction at the Karlsruhe Institute of Technology north campus, and makes use of the Karlsruhe Tritium Laboratory built as a prototype for the ITER project. The combination of a large retarding-potential electrostatic-magnetic spectrometer and an intense gaseous molecular tritium source makes possible a sensitivity to neutrino mass of 0.2 eV, about an order of magnitude below present laboratory limits. The measurement is kinematic and independent of whether the neutrino is Dirac or Majorana. The status of the project is summarized briefly in this report.
GSI Oscillations as Interference of Neutrino Flavour Mass--Eigenstates and Measuring Process
A. N. Ivanov; P. Kienle
2014-06-10T23:59:59.000Z
This paper is addressed to the proof of the important role of measuring apparatus, i.e. the measuring process, in the formation of necessary and sufficient conditions for the explanation of a time modulation of K-shell electron capture (EC) decay rates of hydrogen-like (H-like) heavy ions (or the GSI oscillations) as the interference of neutrino mass-eigenstates of the electron neutrino constituents. For our analysis we use a toy-model, which has been recently proposed by Peshkin arXiv: 1403.4292 [nucl-th] for a verification of the mechanism of the GSI oscillations as the interference of neutrino mass-eigenstates by Ivanov and Kienle Phys. Rev. Lett. 103, 062502 (2009).
GSI Oscillations as Interference of Neutrino Flavour Mass--Eigenstates and Measuring Process
Ivanov, A N
2014-01-01T23:59:59.000Z
This paper is addressed to the proof of the important role of measuring apparatus, i.e. the measuring process, in the formation of necessary and sufficient conditions for the explanation of a time modulation of K-shell electron capture (EC) decay rates of hydrogen-like (H-like) heavy ions (or the GSI oscillations) as the interference of neutrino mass-eigenstates of the electron neutrino constituents. For our analysis we use a toy-model, which has been recently proposed by Peshkin arXiv: 1403.4292 [nucl-th] for a verification of the mechanism of the GSI oscillations as the interference of neutrino mass-eigenstates by Ivanov and Kienle Phys. Rev. Lett. 103, 062502 (2009).
E. M. Lipmanov
2008-10-01T23:59:59.000Z
The absolute neutrino masses and type of neutrino mass hierarchy are among the main problems in neutrino physics. Top-quark mass is another topical problem in particle physics. These problems extend the old puzzle of electron-muon mass ratio close to the fine structure constant, which is still not solved by known theory. Here I continue the search for a general flavor pattern that may incorporate these problems. Relations between neutrino/electron and electron/top-quark pole mass ratios are obtained from supposition that realistic elementary particle dimensionless bare flavor quantities are small deviated (measured by universal parameter e) from the values of a stated flavor pattern (at e=0) and experimental data hints. With the world average t-quark mass data the sum of QD-neutrino masses is estimated (0.50 +- 0.003)eV in agreement with cosmological constraints and known QD-neutrino mass estimations from experimental data on neutrino oscillation mass-squared differences.
Independent measurement of the neutrino mixing angle ?13 via neutron capture on hydrogen at Daya Bay
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Jaffe D. E.; Jaffe, D.E., et al. Daya Bay Collaboration
2014-10-01T23:59:59.000Z
A new measurement of the ?13 mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture result and an improvement on the precision of the ?13 measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GWth reactors, the rate deficit observed at the far hall is interpreted as sin22?13=0.083±0.018 in the three-flavor oscillation model. When combined with the gadolinium-capture result from Daya Bay, we obtain sin22?13=0.089±0.008 as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.
Independent measurement of the neutrino mixing angle ?13 via neutron capture on hydrogen at Daya Bay
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Jaffe D. E.; Jaffe, D.E., et al. Daya Bay Collaboration
2014-10-01T23:59:59.000Z
A new measurement of the ?13 mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture result and an improvement on the precision of the ?13 measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GWth reactors, the rate deficit observed at the far hall is interpreted as sin22?13=0.083±0.018 in the three-flavor oscillationmore »model. When combined with the gadolinium-capture result from Daya Bay, we obtain sin22?13=0.089±0.008 as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.« less
Magnetic Dipole Moment of Neutrino
Samina S. Masood
2015-06-03T23:59:59.000Z
We recalculate the magnetic moment of neutrinos in a hot and dense medium. The magnetic dipole moment of neutrinos is modified at high temperature and chemical potential. We show that the magnetic dipole moment of electron neutrino does not get a significant contribution from thermal background to meet the cosmological bound. However, chemical potential contribution to the magnetic moment is non-ignorable even when chemical potential is an order of magnitude greater than the electron mass. It is demonstrated that this effect is more significant in the models with an extended Higgs sector through neutrino mixing.
Dark matter, neutrino masses and high scale validity of an inert Higgs doublet model
Nabarun Chakrabarty; Dilip Kumar Ghosh; Biswarup Mukhopadhyaya; Ipsita Saha
2015-01-15T23:59:59.000Z
We consider a two-Higgs doublet scenario containing three $SU(2)_L$ singlet heavy neutrinos with Majorana masses. The second scalar doublet as well as the neutrinos are odd under a $Z_2$ symmetry. This scenario not only generates Majorana masses for the light neutrinos radiatively but also makes the lighter of the neutral $Z_2$-odd scalars an eligible dark matter candidate, in addition to triggering leptogenesis at the scale of the heavy neutrino masses. Taking two representative values of this mass scale, we identify the allowed regions of the parameter space of the model, which are consistent with all dark matter constraints. At the same time, the running of quartic couplings in the scalar potential to high scales is studied, thus subjecting the regions consistent with dark matter constraints to further requirements of vacuum stability, perturbativity and unitarity. It is found that part of the parameter space is consistent with all of these requirements all the way up to the Planck scale, and also yields the correct signal strength in the diphoton channel for the scalar observed at the Large Hadron Collider.
Oscillating Decay Rate in Electron Capture and the Neutrino Mass Difference
Peshkin, Murray
2014-01-01T23:59:59.000Z
Reported oscillations in the rate of decay of certain ions by K-electron capture have raised questions about whether and how such oscillations can arise in quantum mechanical theory and whether they can measure the neutrino mass difference. Here I show that simple principles of quantum mechanics answer some questions and clarify what must be done theoretically or experimentally to answer some others.
Fujii, Kanji
2014-01-01T23:59:59.000Z
On the basis of quantum field theory, we consider a unified description of various processes accompanied by neutrinos, namely weak decays and oscillation processes. The structures of the expectation values of flavor-neutrino numbers with respect to neutrino-source hadron state are investigated. Due to the smallness of neutrino masses, we naturally obtain the old (i.e. pre-mixing) formulas of decay probabilities. Together, it is shown that the oscillation formulas, similar to the usual ones, are applied irrespectively of the details of neutrino-producing processes. The derived oscillation formulas are the same in form as the usually used ones except for the oscillation length.
Fermion masses and mixing in a 4+1 dimensional SU(5) domain-wall brane model
Callen, Benjamin D.; Volkas, Raymond R. [School of Physics, University of Melbourne, Victoria 3010 (Australia)
2011-03-01T23:59:59.000Z
We study the fermion mass and mixing hierarchy problems within the context of the SU(5) 4+1d domain-wall brane model of Davies, George, and Volkas. In this model, the ordinary fermion mass relations of SU(5) grand unified theories are avoided, since the masses are proportional to overlap integrals of the profiles of the electroweak Higgs and the chiral components of each fermion, which are split into different 3+1d hyperplanes according to their hypercharges. We show that the fermion mass hierarchy without electroweak mixing can be generated naturally from these splittings, that generation of the Cabibbo-Kobayashi-Maskawa matrix looks promising, and that the Cabibbo angle, along with the mass hierarchy, can be generated for the case of Majorana neutrinos from a more modest hierarchy of parameters. We also show that, under some assumptions made on the parameter space, the generation of realistic lepton mixing angles is not possible without fine-tuning, which argues for a flavor symmetry to enforce the required relations.
Is it possible to explain neutrino masses with scalar dark matter?
Boehm, Celine [LAPTH, UMR 5108, 9 chemin de Bellevue - BP 110, 74941 Annecy-Le-Vieux (France); Farzan, Yasaman [Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Hambye, Thomas [Instituto de Fisica Teorica, Universidad Autonoma de Madrid, Cantoblanco (Spain); Palomares-Ruiz, Sergio; Pascoli, Silvia [Institute for Particle Physics Phenomenology, University of Durham, Durham DH1 3LE (United Kingdom)
2008-02-15T23:59:59.000Z
We present a scenario in which a remarkably simple relation linking dark matter properties and neutrino masses naturally emerges. This framework points towards a low energy theory where the neutrino mass originates from the existence of a light scalar dark matter particle in the keV-MeV mass range. We discuss different ways to constrain and test this scenario by means of astrophysical and cosmological observations as well as laboratory experiments. Finally, we point out that one interesting aspect is that the implied mass range is compatible with the one required for the explanation of the mysterious emission of 511 keV photons from the center of our galaxy in terms of dark matter annihilation into e{sup +}e{sup -} pairs.
Double-beta-decay mass constraints on 17-keV neutrinos
Haxton, W.C. (Department of Physics, FM-15, University of Washington, Seattle, Washington (USA))
1991-10-28T23:59:59.000Z
Attempts to reconcile a 17-keV neutrino with constraints from astrophysics and double beta decay have led to model Majorana neutrino mass matrices with vanishing (or nearly vanishing) electron-electron components. A simple parametrization is presented of the higher-order mass effects on the intermediate-state propagator through which 0{nu} {beta}{beta} decay can still occur. For light-mass eigenstates, the 0{nu} and 2{nu} rates are proportional, with the ratio depending on a weighted sum over mass eigenstates {l angle}{ital m}{sub {nu}}{sup 3}{r angle}{sub {ital L}{ital L}}{sup Maj}. Thus, model 0{nu} {beta}{beta} decay rates can be predicted with confidence.
Hernandez-Galeana, A
2011-01-01T23:59:59.000Z
The {\\it theory unifying spin and charges and predicting families}, proposed by N.S.M.B., predicts at the low energy regime two (in the mixing matrix elements decoupled) groups of four families. There are two kinds of contributions to mass matrices in this theory. One kind distinguishes on the tree level only among the members of one family, that is among the $u$-quark, $d$-quark, neutrino and electron, the left and right handed, while the other kind distinguishes only among the families. Mass matrices for $d$-quarks and electrons are on the tree level correspondingly strongly correlated and so are mass matrices for $u$-quarks and neutrinos, up to the term, the Majorana term, which is nonzero only for right handed neutrinos. Beyond the tree level both kinds of contributions start to contribute coherently and it is expected that a detailed study of properties of mass matrices beyond the tree level explains drastic differences in masses and mixing matrices between quarks and leptons. We report in this paper on ...
On the minimum dark matter mass testable by neutrinos from the Sun
Busoni, Giorgio; Simone, Andrea De; Huang, Wei-Chih, E-mail: giorgio.busoni@sissa.it, E-mail: andrea.desimone@sissa.it, E-mail: wei-chih.huang@sissa.it [SISSA and INFN, Sezione di Trieste, via Bonomea 265, I-34136 Trieste (Italy)
2013-07-01T23:59:59.000Z
We discuss a limitation on extracting bounds on the scattering cross section of dark matter with nucleons, using neutrinos from the Sun. If the dark matter particle is sufficiently light (less than about 4 GeV), the effect of evaporation is not negligible and the capture process goes in equilibrium with the evaporation. In this regime, the flux of solar neutrinos of dark matter origin becomes independent of the scattering cross section and therefore no constraint can be placed on it. We find the minimum values of dark matter masses for which the scattering cross section on nucleons can be probed using neutrinos from the Sun. We also provide simple and accurate fitting functions for all the relevant processes of GeV-scale dark matter in the Sun.
Heavy Sterile Neutrinos and Neutrinoless Double Beta Decay
P. Bamert; C. P. Burgess; R. N. Mohapatra
1994-10-12T23:59:59.000Z
We investigate the possibility of producing neutrinoless double beta decay without having an electron neutrino with a mass in the vicinity of 1 eV. We do so by having a much lighter electron neutrino mix with a much heavier (m > 1 GeV) sterile neutrino. We study the constraints on the masses and mixings of such heavy sterile neutrinos from existing laboratory, astrophysical and cosmological information, and discuss the properties it would require in order to produce a detectable signal in current searches for neutrinoless double beta decay.
Aravind Natarajan; Andrew R. Zentner; Nicholas Battaglia; Hy Trac
2014-09-04T23:59:59.000Z
We examine the importance of baryonic feedback effects on the matter power spectrum on small scales, and the implications for the precise measurement of neutrino masses through gravitational weak lensing. Planned large galaxy surveys such as the Large Synoptic Sky Telescope (LSST) and Euclid are expected to measure the sum of neutrino masses to extremely high precision, sufficient to detect non-zero neutrino masses even in the minimal mass normal hierarchy. We show that weak lensing of galaxies while being a very good probe of neutrino masses, is extremely sensitive to baryonic feedback processes. We use publicly available results from the Overwhelmingly Large Simulations (OWLS) project to investigate the effects of active galactic nuclei feedback, the nature of the stellar initial mass function, and gas cooling rates, on the measured weak lensing shear power spectrum. Using the Fisher matrix formalism and priors from CMB+BAO data, we show that when one does not account for feedback, the measured neutrino mass may be substantially larger or smaller than the true mass, depending on the dominant feedback mechanism, with the mass error |\\Delta m_nu| often exceeding the mass m_nu itself. We also consider gravitational lensing of the cosmic microwave background (CMB) and show that it is not sensitive to baryonic feedback on scales l < 2000, although CMB experiments that aim for sensitivities sigma(m_nu) < 0.02 eV will need to include baryonic effects in modeling the CMB lensing potential. A combination of CMB lensing and galaxy lensing can help break the degeneracy between neutrino masses and baryonic feedback processes. We conclude that future large galaxy lensing surveys such as LSST and Euclid can only measure neutrino masses accurately if the matter power spectrum can be measured to similar accuracy.
Neutrino masses from clustering of red and blue galaxies: a test of astrophysical uncertainties
Molly E. C. Swanson; Will J. Percival; Ofer Lahav
2010-09-06T23:59:59.000Z
Combining measurements of the galaxy power spectrum and the cosmic microwave background (CMB) is a powerful means of constraining the summed mass of neutrino species sum(m_nu), but is subject to systematic uncertainties due to non-linear structure formation, redshift-space distortions and galaxy bias. We empirically test the robustness of neutrino mass results to these effects by separately analyzing power spectra of red and blue galaxies from the Sloan Digital Sky Survey (SDSS-II) Data Release 7 (DR7), combined with the CMB five-year Wilkinson Microwave Anisotropy Probe (WMAP5) data. We consider fitting for a range of maximum wavenumber k using twelve different galaxy bias models. For example, using a new model based on perturbation theory and including redshift space distortions (Saito et al. 2009), the all-galaxy power spectrum combined with WMAP5 for a wavenumber range of kblue galaxy power spectra give 0.41 and 0.63 eV respectively for this model. Using mock catalogues, we find the expected difference in these limits assuming a true neutrino mass of zero is 0.10 + or - 0.14 eV. Thus the difference of 0.22 eV between upper limits on neutrino mass for red and blue galaxies is approximately 1 sigma from the expected value. We find similar results for the other models and k ranges tested. This indicates good agreement for current data but hints at possible issues for next-generation surveys. Being able to perform such systematic tests is advantageous, and future surveys would benefit by including broad galaxy populations and luminosities that enable such a decomposition.
Instanton Induced Neutrino Majorana Masses in CFT Orientifolds with MSSM-like spectra
L. E. Ibanez; A. N. Schellekens; A. M. Uranga
2007-04-25T23:59:59.000Z
Recently it has been shown that string instanton effects may give rise to neutrino Majorana masses in certain classes of semi-realistic string compactifications. In this paper we make a systematic search for supersymmetric MSSM-like Type II Gepner orientifold constructions admitting boundary states associated with instantons giving rise to neutrino Majorana masses and other L- and/or B-violating operators. We analyze the zero mode structure of D-brane instantons on general type II orientifold compactifications, and show that only instantons with O(1) symmetry can have just the two zero modes required to contribute to the 4d superpotential. We however discuss how the addition of fluxes and/or possible non-perturbative extensions of the orientifold compactifications would allow also instantons with $Sp(2)$ and U(1) symmetries to generate such superpotentials. In the context of Gepner orientifolds with MSSM-like spectra, we find no models with O(1) instantons with just the required zero modes to generate a neutrino mass superpotential. On the other hand we find a number of models in one particular orientifold of the Gepner model $(2,4,22,22)$ with $Sp(2)$ instantons with a few extra uncharged non-chiral zero modes which could be easily lifted by the mentioned effects. A few more orientifold examples are also found under less stringent constraints on the zero modes. This class of $Sp(2)$ instantons have the interesting property that R-parity conservation is automatic and the flavour structure of the neutrino Majorana mass matrices has a simple factorized form.
Subgrid models for mass and thermal diffusion in turbulent mixing
Sharp, David H [Los Alamos National Laboratory; Lim, Hyunkyung [STONY BROOK UNIV; Li, Xiao - Lin [STONY BROOK UNIV; Gilmm, James G [STONY BROOK UNIV
2008-01-01T23:59:59.000Z
We are concerned with the chaotic flow fields of turbulent mixing. Chaotic flow is found in an extreme form in multiply shocked Richtmyer-Meshkov unstable flows. The goal of a converged simulation for this problem is twofold: to obtain converged solutions for macro solution features, such as the trajectories of the principal shock waves, mixing zone edges, and mean densities and velocities within each phase, and also for such micro solution features as the joint probability distributions of the temperature and species concentration. We introduce parameterized subgrid models of mass and thermal diffusion, to define large eddy simulations (LES) that replicate the micro features observed in the direct numerical simulation (DNS). The Schmidt numbers and Prandtl numbers are chosen to represent typical liquid, gas and plasma parameter values. Our main result is to explore the variation of the Schmidt, Prandtl and Reynolds numbers by three orders of magnitude, and the mesh by a factor of 8 per linear dimension (up to 3200 cells per dimension), to allow exploration of both DNS and LES regimes and verification of the simulations for both macro and micro observables. We find mesh convergence for key properties describing the molecular level of mixing, including chemical reaction rates between the distinct fluid species. We find results nearly independent of Reynolds number for Re 300, 6000, 600K . Methodologically, the results are also new. In common with the shock capturing community, we allow and maintain sharp solution gradients, and we enhance these gradients through use of front tracking. In common with the turbulence modeling community, we include subgrid scale models with no adjustable parameters for LES. To the authors' knowledge, these two methodologies have not been previously combined. In contrast to both of these methodologies, our use of Front Tracking, with DNS or LES resolution of the momentum equation at or near the Kolmogorov scale, but without resolving the Batchelor scale, allows a feasible approach to the modeling of high Schmidt number flows.
Martins, R. A. [Centro de Analise Matematica, Geometria e Sistemas Dinamicos, Departamento de Matematica, Instituto Superior Tecnico, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal)
2007-08-15T23:59:59.000Z
The recent extension of the standard model to include massive neutrinos in the framework of noncommutative geometry and the spectral action principle involves new scalar fields and their interactions with the usual complex scalar doublet. After ensuring that they bring no unphysical consequences, we address the question of how these fields affect the physics predicted in the Weinberg-Salam theory, particularly in the context of the electroweak phase transition. Applying the Dolan-Jackiw procedure, we calculate the finite temperature corrections, and find that the phase transition is first order. The new scalar interactions significantly improve the stability of the electroweak Z string, through the 'bag' phenomenon described by Vachaspati and Watkins ['Bound states can stabilize electroweak strings', Phys. Lett. B 318, 163-168 (1993)]. (Recently, cosmic strings have climbed back into interest due to a new evidence.) Sourced by static embedded strings, an internal space analogy of Cartan's torsion is drawn, and a possible Higgs-force-like 'gravitational' effect of this nonpropagating torsion on the fermion masses is described. We also check that the field generating the Majorana mass for the {nu}{sub R} is nonzero in the physical vacuum.
No Collective Neutrino Flavor Conversions during the Supernova Accretion Phase
Chakraborty, Sovan; Mirizzi, Alessandro; Saviano, Ninetta; Tomas, Ricard [II Institut fuer Theoretische Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Fischer, Tobias [GSI, Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt (Germany); Technische Universitaet Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)
2011-10-07T23:59:59.000Z
We perform a dedicated study of the supernova (SN) neutrino flavor evolution during the accretion phase, using results from recent neutrino radiation hydrodynamics simulations. In contrast to what was expected in the presence of only neutrino-neutrino interactions, we find that the multiangle effects associated with the dense ordinary matter suppress collective oscillations. The matter suppression implies that neutrino oscillations will start outside the neutrino decoupling region and therefore will have a negligible impact on the neutrino heating and the explosion dynamics. Furthermore, the possible detection of the next galactic SN neutrino signal from the accretion phase, based on the usual Mikheyev-Smirnov-Wolfenstein effect in the SN mantle and Earth matter effects, can reveal the neutrino mass hierarchy in the case that the mixing angle {theta}{sub 13} is not very small.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5(Million Cubic Feet) Oregon (Including Vehicle Fuel) (Million Cubic Feet) Natural Gas Delivered to What Certificates ShouldNeutrino cross section
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5(Million Cubic Feet) Oregon (Including Vehicle Fuel) (Million Cubic Feet) Natural Gas Delivered to What Certificates ShouldNeutrinoEPS
Oscillating Decay Rate in Electron Capture and the Neutrino Mass Difference
Murray Peshkin
2014-10-20T23:59:59.000Z
Reported oscillations in the rate of decay of certain ions by K-electron capture have raised questions about whether and how such oscillations can arise in quantum mechanical theory and whether they can measure the neutrino mass difference. Here I show that simple principles of quantum mechanics answer some questions and clarify what must be done theoretically or experimentally to answer some others. The principal result is that quantum mechanics does allow mass-difference-dependent oscillations in principle, but it imposes conditions not obeyed by the approximate dynamical models that have been put forth up to now. What needs to be done experimentally and theoretically is discussed.
Seesaw enhancement of lepton mixing
Smirnov, A.Y. (Institute for Advanced Study, Princeton, New Jersey 08540 (United States) International Centre for Theoretical Physics, 34100 Trieste (Italy) Institute for Nuclear Research, 117312 Moscow (Russian Federation))
1993-10-01T23:59:59.000Z
The seesaw mechanism of neutrino mass generation may enhance lepton mixing up to maximal even if the Dirac mass matrices of leptons have a structure similar to that in the quark sector. Two sets of conditions for such an enhancement are found. The first one includes the seesaw generation of heavy Majorana masses for right-handed neutrinos and a universality of Yukawa couplings which can follow from the unification of neutrinos with new superheavy neutral leptons. The second set is related to the lepton number symmetry of the Yukawa interactions in the Dirac basis of neutrinos. Models which realize these conditions have a strong hierarchy or strong degeneration of Majorana masses of the right-handed neutrinos.
Neutrinoless Double Beta Decay and Heavy Sterile Neutrinos
Manimala Mitra; Goran Senjanovic; Francesco Vissani
2011-12-21T23:59:59.000Z
The experimental rate of neutrinoless double beta decay can be saturated by the exchange of virtual sterile neutrinos, that mix with the ordinary neutrinos and are heavier than 200 MeV. Interestingly, this hypothesis is subject only to marginal experimental constraints, because of the new nuclear matrix elements. This possibility is analyzed in the context of the Type I seesaw model, performing also exploratory investigations of the implications for heavy neutrino mass spectra, rare decays of mesons as well as neutrino-decay search, LHC, and lepton flavor violation. The heavy sterile neutrinos can saturate the rate only when their masses are below some 10 TeV, but in this case, the suppression of the light-neutrino masses has to be more than the ratio of the electroweak scale and the heavy-neutrino scale; i.e., more suppressed than the naive seesaw expectation. We classify the cases when this condition holds true in the minimal version of the seesaw model, showing its compatibility (1) with neutrinoless double beta rate being dominated by heavy neutrinos and (2) with any light neutrino mass spectra. The absence of excessive fine-tunings and the radiative stability of light neutrino mass matrices, together with a saturating sterile neutrino contribution, imply an upper bound on the heavy neutrino masses of about 10 GeV. We extend our analysis to the Extended seesaw scenario, where the light and the heavy sterile neutrino contributions are completely decoupled, allowing the sterile neutrinos to saturate the present experimental bound on neutrinoless double beta decay. In the models analyzed, the rate of this process is not strictly connected with the values of the light neutrino masses, and a fast transition rate is compatible with neutrinos lighter than 100 meV.
Natural Dirac Neutrinos from Warped Extra Dimension
Jackson M. S. Wu
2010-06-29T23:59:59.000Z
Dirac neutrinos arising from gauged discrete symmetry \\`a la Krauss-Wilczek are implemented in the minimal custodial Randall-Sundrum model. In the case of a normal hierarchy, all lepton masses and mixing pattern can be naturally reproduced at the TeV scale set by the electroweak constraints, while simultanously satisfy bounds from lepton flavour violation. A nonzero neutrino mixing angle, $\\theta_{13}$, is generic in the scenario, as well as the existence of sub-TeV right-handed Kaluza-Klein neutrinos, which may be searched for at the LHC.
Precision Measurements of Long-Baseline Neutrino Oscillation at LBNF
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Worcester, Elizabeth
2015-08-06T23:59:59.000Z
In a long-baseline neutrino oscillation experiment, the primary physics objectives are to determine the neutrino mass hierarchy, to determine the octant of the neutrino mixing angle ?23, to search for CP violation in neutrino oscillation, and to precisely measure the size of any CP-violating effect that is discovered. This presentation provides a brief introduction to these measurements and reports on efforts to optimize the design of a long-baseline neutrino oscillation experiment, the status of LBNE, and the transition to an international collaboration at LBNF.
Neutrinos in Physics and Astrophysics
G. G. Raffelt
2003-03-05T23:59:59.000Z
The observed flavor oscillations of solar and atmospheric neutrinos determine several elements of the leptonic mixing matrix, but leave open the small mixing angle Theta_13, a possible CP-violating phase, the mass ordering, the absolute mass scale m_nu, and the Dirac vs. Majorana property. Progress will be made by long-baseline, tritium endpoint, and 2-beta decay experiments. The best constraint on m_nu obtains from cosmological precision observables, implying that neutrinos contribute very little to the dark matter. However, massive Majorana neutrinos may well be responsible for ordinary matter by virtue of the leptogenesis mechanism for creating the baryon asymmetry of the universe. In future, neutrinos could play an important role as astrophysical messengers if point sources are discovered in high-energy neutrino telescopes. In the low-energy range, a high-statistics observation of a galactic supernova would allow one to observe directly the dynamics of stellar collapse and perhaps to discriminate between certain mixing scenarios. An observation of the relic neutrinos from all past supernovae has come within reach.
Monreal, Benjamin
The shape of the beta-decay energy distribution is sensitive to the mass of the electron neutrino. Attempts to measure the endpoint shape of tritium decay have so far seen no distortion from the zero-mass form, thus placing ...
SU(5) Completion of the Dark Scalar Doublet Model of Radiative Neutrino Mass
Ernest Ma
2007-10-11T23:59:59.000Z
Adding a second scalar doublet (eta^+,eta^0) and three neutral singlet fermions N_{1,2,3} to the Standard Model of particle interactions with a new Z_2 symmetry, it has been shown that eta^0_R or eta^0_I is a good dark-matter candidate and seesaw neutrino masses are generated radiatively. A minimal extension of this new idea is proposed to allow for its SU(5) completion. Supersymmetric unification is then possible, and leptoquarks of a special kind are predicted at the TeV scale.
Neutrino Oscillations in the Dualized Standard Model
J Bordes; HM Chan; J. Pfaudler; ST Tsou
1998-02-25T23:59:59.000Z
A method developed from the Dualized Standard Model for calculating the quark CKM matrix and masses is applied to the parallel problem in neutrino oscillations. Taking the parameters determined from quarks and the masses of two neutrinos: $m_3^2 \\sim 10^{-2} - 10^{-3} eV^2$ suggested by atmospheric neutrino data, and $m_2^2 \\sim 10^{-10} eV^2$ suggested by the long wave-length oscillation (LWO) solution of the solar neutrino problem, one obtains from a parameter-free calculation all the mixing angles in reasonable agreement with existing experiment. However, the scheme is found not to accommodate comfortably the mass values $m_2^2 \\sim 10^{-5} eV^2$ suggested by the MSW solution for solar neutrinos.
Neutrino Oscillations in the Dualized Standard Model
Bordes, J; Pfaudler, J; Tsou, S T; Chan, HM; Tsou, ST
1998-01-01T23:59:59.000Z
A method developed from the Dualized Standard Model for calculating the quark CKM matrix and masses is applied to the parallel problem in neutrino oscillations. Taking the parameters determined from quarks and the masses of two neutrinos: $m_3^2 \\sim 10^{-2} - 10^{-3} eV^2$ suggested by atmospheric neutrino data, and $m_2^2 \\sim 10^{-10} eV^2$ suggested by the long wave-length oscillation (LWO) solution of the solar neutrino problem, one obtains from a parameter-free calculation all the mixing angles in reasonable agreement with existing experiment. However, the scheme is found not to accommodate comfortably the mass values $m_2^2 \\sim 10^{-5} eV^2$ suggested by the MSW solution for solar neutrinos.
Neutrino 2012: Outlook - theory
Smirnov, A Yu
2012-01-01T23:59:59.000Z
Ongoing developments in theory and phenomenology are related to the measured large value of 1-3 mixing and indications of significant deviation of the 2-3 mixing from maximal one. "Race" for the mass hierarchy has started and there is good chance that multi-megaton scale atmospheric neutrino detectors with low threshold (e.g. PINGU) will establish the type of hierarchy. Two IceCube candidates of the PeV cosmic neutrinos if confirmed, is the beginning of new era of high energy neutrino astronomy. Accumulation of data on solar neutrinos (energy spectrum, D-N asymmetry, value of $\\Delta m^2_{21}$) may uncover some new physics. The Tri-bimaximal mixing is disfavored and the existing discrete symmetry paradigm may change. The confirmed QLC prediction, $\\theta_{13} \\approx \\theta_{C}/\\sqrt{2}$, testifies for GUT, seesaw and some symmetry at very high scales. However, the same value of 1-3 mixing can be obtained in various ways which have different implications. The situation in lepton sector changes from special (w...
CP Violation in Neutrinoless Double Beta Decay and Neutrino Oscillation
T. Fukuyama; K. Matsuda; H. Nishiura
1998-03-03T23:59:59.000Z
Taking account of possible CP violation, we discuss about the constraints on the lepton mixing angles from the neutrinoless double beta decay and from the neutrino oscillation for the three flavour Majorana neutrinos. From the CHORUS oscillation experiment, combined with the data of neutrinoless double beta decay, we show that the large angle solution of (\\theta_{23}) is improbable if the neutrino mass (m_3) of the third generation is a candidate of hot dark matters.
Conversion of experimental half-life to effective electron neutrino mass in 0nubetabeta decay
Smolnikov, Anatoly; Grabmayr, Peter [Joint Institute for Nuclear Research, Dubna, Russia, and Institute for Nuclear Research of the Russian Academy of Sciences, Moscow (Russian Federation); Kepler Center for Astro and Particle Physics, Eberhard Karls Universitaet Tuebingen (Germany)
2010-02-15T23:59:59.000Z
The Germanium Detector Array (GERDA) collaboration will be searching for neutrinoless double beta decay of {sup 76}Ge. As a result it will measure the half-life T{sub 1/2} of this rare process; or at least a new value for the lower limit for T{sub 1/2} will be derived. The sensitivity of the GERDA experiment on the effective electron neutrino mass
Neutrino Oscillations Physics 135c
Golwala, Sunil
Neutrino Oscillations Gary Cheng Physics 135c 6/1/07 #12;Introduction: Theory Neutrinos have mass neutrinos are produced. The difference between the mass eigenstates and the flavor eigenstates of neutrinos is what causes neutrino oscillations. #12;Introduction: Theory 2 The mass eigenstates 1, 2, 3
New Upper Limits on the Tau Neutrino Mass from Primordial Helium Considerations
A. D. Dolgov; I. Z. Rothstein
1993-02-23T23:59:59.000Z
In this paper we reconsider recently derived bounds on $MeV$ tau neutrinos, taking into account previously unaccounted for effects. We find that, assuming that the neutrino life-time is longer than $O(100~sec)$, the constraint $N_{eff}Majorana neutrinos and $0.74~(MeV)neutrinos. Given that the present laboratory bound is 35 MeV, our results lower the present bound to $0.5$ and $0.74$ for Majorana and Dirac neutrinos respectively.
Disentangling the various Mechanisms of neutrinoless double beta decay to extract the neutrino mass
Vergados, J. D. [Physics Department, University of Ioannina, Ioannina, GR 451 10, Greece and Theory Division, CERN 1211, Geneva 23 (Greece)
2011-12-16T23:59:59.000Z
It is well known that there exist many mechanisms that may contribute to neutrinoless double beta decay. By exploiting the fact that the associated nuclear matrix elements are target dependent we show that, given definite experimental results on a sufficient number of targets, one can determine or sufficiently constrain all lepton violating parameters including the mass term. As a specific example we show that, given the observation of the 0{nu}{beta}{beta}-decay in three different nuclei, e.g. {sup 76}Ge, {sup 100}Mo and {sup 130}Te, and assuming just three active lepton number violating parameters, e.g. light and heavy neutrino mass mechanisms in left handed currents as well as R-parity breaking SUSY mechanism, one may determine all lepton violating parameters, provided that they are relatively real.
CUORE and beyond: Bolometric techniques to explore inverted neutrino mass hierarchy
Artusa, D. R. [Univ. of South Carolina, Columbia, SC (United States); INFN - LAb Nazionali del Gran Sasso, Assergi (Italy); Avignone, F. T. [Univ. of South Carolina, Columbia, SC (United States); Azzolini, O. [INFN - Laboratori Nazionali di Legnaro, Legnaro (Italy); Balata, M. [INFN - Lab Nazionali del Gran Sasso, Assergi (Italy); Banks, T. I. [INFN - Lab Nazionali del Gran Sasso, Assergi (Italy); Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bari, G. [INFN - Sezione di Bologna, Bologna (Italy); Beeman, J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Bellini, F. [Sapienza Univ. di Roma, Roma (Italy); INFN - Sezione di Roma, Roma (Italy); Bersani, A. [INFN - Sezione di Genova, Genova (Italy); Biassoni, M. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Brofferio, C. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Bucci, C. [INFN - Lab Nazionali del Gran Sasso, Assergi (Italy); Cai, X. Z. [Chinese Academy of Sciences (CAS), Shanghai (China); Camacho, A. [INFN - Laboratori Nazionali di Legnaro, Legnaro (Italy); Canonica, L. [INFN - Lab Nazionali del Gran Sasso, Assergi (Italy); Cao, X. G. [Chinese Academy of Sciences (CAS), Shanghai (China); Capelli, S. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Carbone, L. [INFN - Sezione di Milano Bicocca, Milano (Italy); Cardani, L. [Sapienza Univ. di Roma, Roma (Italy); INFN - Sezione di Roma, Roma (Italy); Carrettoni, M. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Casali, N. [INFN - Lab Nazionali del Gran Sasso, Assergi (Italy); Chiesa, D. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Chott, N. [Univ. of South Carolina, Columbia, SC (United States); Clemenza, M. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Copello, S. [Univ. di Genova, Genova (Italy); Cosmelli, C. [Sapienza Univ. di Roma, Roma (Italy); INFN - Sezione di Roma, Roma (Italy); Cremonesi, O. [INFN - Sezione di Milano Bicocca, Milano (Italy); Creswick, R. J. [Univ. of South Carolina, Columbia, SC (United States); Dafinei, I. [INFN - Sezione di Roma, Roma (Italy); Dally, A. [Univ. of Wisconsin, Madison, WI (United States); Datskov, V. [INFN - Sezione di Milano Bicocca, Milano (Italy); De Biasi, A. [INFN - Laboratori Nazionali di Legnaro, Legnaro (Italy); Deninno, M. M. [INFN - Sezione di Bologna, Bologna (Italy); Di Domizio, S. [Univ. di Genova, Genova (Italy); INFN - Sezione di Genova, Genova (Italy); di Vacri, M. L. [INFN - Lab Nazionali del Gran Sasso, Assergi (Italy); Ejzak, L. [Univ. of Wisconsin, Madison, WI (United States); Fang, D. Q. [Chinese Academy of Sciences (CAS), Shanghai (China); Farach, H. A. [Univ. of South Carolina, Columbia, SC (United States); Faverzani, M. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Fernandes, G. [Univ. de Genova, Genova (Italy); INFN - Sezione di Genova, Genova (Italy); Ferri, E. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Ferroni, F. [Sapienza Univ. di Roma, Roma (Italy); INFN - Sezione di Roma, Roma (Italy); Fiorini, E. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Franceschi, M. A. [INFN - Lab. Nazionali di Frascati, Frascati (Italy); Freedman, S. J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); INFN- Sezione di Milano Bicocca, Milano (Italy); Fujikawa, B. K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Giachero, A. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Gironi, L. [Univ. di Milano- Bicocca, Milano (Italy); INFN - Sezione di Milano Bicocca, Milano (Italy); Giuliani, A. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Orsay Campus (France)
2015-01-01T23:59:59.000Z
The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will search for neutrinoless double beta decay of ął?Te. With 741 kg of TeO? crystals and an excellent energy resolution of 5 keV (0.2%) at the region of interest, CUORE will be one of the most competitive neutrinoless double beta decay experiments on the horizon. With five years of live time, CUORE projected neutrinoless double beta decay half-life sensitivity is 1.6 × 10˛? y at 1? (9.5 × 10˛? y at the 90% confidence level), which corresponds to an upper limit on the effective Majorana mass in the range 40–100 meV (50–130 meV). Further background rejection with auxiliary light detector can significantly improve the search sensitivity and competitiveness of bolometric detectors to fully explore the inverted neutrino mass hierarchy with ął?Te and possibly other double beta decay candidate nuclei.
CUORE and Beyond: Bolometric Techniques to Explore Inverted Neutrino Mass Hierarchy
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Artusa, D.R.; Avignone, F.T.; Azzolini, O.; Balata, M.; Banks, T.I.; Bari, G.; Beeman, J.; Bellini, F.; Bersani, A.; Biassoni, M.; et al
2015-01-01T23:59:59.000Z
The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will search for neutrinoless double beta decay of 130Te. With 741 kg of TeO2 crystals and an excellent energy resolution of 5 keV (0.2%) at the region of interest, CUORE will be one of the most competitive neutrinoless double beta decay experiments on the horizon. With five years of live time, CUORE projected neutrinoless double beta decay half-life sensitivity is 1.6 × 1026 y at 1? (9.5 × 1025 y at the 90% confidence level), which corresponds to an upper limit on the effective Majorana mass in the range 40–100 meVmore »(50–130 meV). Further background rejection with auxiliary light detector can significantly improve the search sensitivity and competitiveness of bolometric detectors to fully explore the inverted neutrino mass hierarchy with 130Te and possibly other double beta decay candidate nuclei.« less
CDF/PHYS/TOP/PUBLIC/7303 Measurement of the Top Quark Mass using the Neutrino Weighting Algorithm on
Quigg, Chris
CDF/PHYS/TOP/PUBLIC/7303 Measurement of the Top Quark Mass using the Neutrino Weighting Algorithm measure the top quark mass using 19 t â?˘ t candidate events in which both W bosons from top quarks decay according to the t â?˘ t decay hypothesis and we measure a top mass of 168.1 +11.0 -9.8 (stat) Â± 8.6(syst) Ge
Determining the neutrino mass hierarchy and CP violation in NoVA with a second off-axis detector
Mena, Olga; /Fermilab; Palomares-Ruiz, Sergio; /Vanderbilt U.; Pascoli, Silvia; /CERN /Durham U., IPPP
2005-10-01T23:59:59.000Z
We consider a Super-NOVA-like experimental configuration based on the use of two detectors in a long-baseline experiment as NOVA. We take the far detector as in the present NOVA proposal and add a second detector at a shorter baseline. The location of the second off-axis detector is chosen such that the ratio L/E is the same for both detectors, being L the baseline and E the neutrino energy. We consider liquid argon and water- Cerenkov techniques for the second off-axis detector and study, for different experimental setups, the detector mass required for the determination of the neutrino mass hierarchy, for different values of {theta}{sub 13}. We also study the capabilities of such an experimental setup for determining CP-violation in the neutrino sector. Our results show that by adding a second off-axis detector a remarkable enhancement on the capabilities of the current NOVA experiment could be achieved.
P. S. Barbeau; J. I. Collar; O. Tench
2007-01-07T23:59:59.000Z
A new type of radiation detector, a p-type modified electrode germanium diode, is presented. The prototype displays, for the first time, a combination of features (mass, energy threshold and background expectation) required for a measurement of coherent neutrino-nucleus scattering in a nuclear reactor experiment. The device hybridizes the mass and energy resolution of a conventional HPGe coaxial gamma spectrometer with the low electronic noise and threshold of a small x-ray semiconductor detector, also displaying an intrinsic ability to distinguish multiple from single-site particle interactions. The present performance of the prototype and possible further improvements are discussed, as well as other applications for this new type of device in neutrino and astroparticle physics (double-beta decay, neutrino magnetic moment and WIMP searches).
Neutrino flavor transformation in core-collapse supernovae
Cherry, John F.; Cherry, John F.
2012-01-01T23:59:59.000Z
unconstrained sectors of neutrino physics. Likewise, shouldinsight into fundamental neutrino physics. We have chosen tostill fundamental neutrino mixing physics unknowns, e.g. ,
Searches for new physics at MiniBooNE : sterile neutrinos and mixing freedom
Karagiorgi, Georgia S. (Georgia Stelios)
2010-01-01T23:59:59.000Z
The MiniBooNE experiment was designed to perform a search for Vu --> Ve oscillations in a region of A[delta]sin 2 20very different from that allowed by standard, three neutrino oscillations, as determined by solar and ...
Updated fit to three neutrino mixing: status of leptonic CP violation
M. C. Gonzalez-Garcia; Michele Maltoni; Thomas Schwetz
2014-12-16T23:59:59.000Z
We present a global analysis of solar, atmospheric, reactor and accelerator neutrino data in the framework of three-neutrino oscillations based on data available in summer 2014. We provide the allowed ranges of the six oscillation parameters and show that their determination is stable with respect to uncertainties related to reactor neutrino and solar neutrino flux predictions. We find that the maximal possible value of the Jarlskog invariant in the lepton sector is $0.0329 \\pm 0.0009$ ($\\pm 0.0027$) at the $1\\sigma$ ($3\\sigma$) level and we use leptonic unitarity triangles to illustrate the ability of global oscillation data to obtain information on CP violation. We discuss "tendencies and tensions" of the global fit related to the octant of $\\theta_{23}$ as well as the CP violating phase $\\delta_\\mathrm{CP}$. The favored values of $\\delta_\\mathrm{CP}$ are around $3\\pi/2$ while values around $\\pi/2$ are disfavored at about $\\Delta\\chi^2 \\simeq 6$. We comment on the non-trivial task to assign a confidence level to this $\\Delta\\chi^2$ value by performing a Monte Carlo study of T2K data.
A measurement of neutrino oscillations with muon neutrinos in the MINOS experiment
Coleman, Stephen James; /William-Mary Coll.
2011-01-01T23:59:59.000Z
Experimental evidence has established that neutrino flavor states evolve over time. A neutrino of a particular flavor that travels some distance can be detected in a different neutrino flavor state. The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline experiment that is designed to study this phenomenon, called neutrino oscillations. MINOS is based at Fermilab near Chicago, IL, and consists of two detectors: the Near Detector located at Fermilab, and the Far Detector, which is located in an old iron mine in Soudan, MN. Both detectors are exposed to a beam of muon neutrinos from the NuMI beamline, and MINOS measures the fraction of muon neutrinos that disappear after traveling the 734 km between the two detectors. One can measure the atmospheric neutrino mass splitting and mixing angle by observing the energy-dependence of this muon neutrino disappearance. MINOS has made several prior measurements of these parameters. Here I describe recently-developed techniques used to enhance our sensitivity to the oscillation parameters, and I present the results obtained when they are applied to a dataset that is twice as large as has been previously analyzed. We measure the mass splitting {Delta}m{sub 23}{sup 2} = (2.32{sub -0.08}{sup +0.12}) x 10{sup -3} eV{sup 2}/c{sup 4} and the mixing angle sin{sup 2}(2{theta}{sub 32}) > 0.90 at 90% C.L. These results comprise the world's best measurement of the atmospheric neutrino mass splitting. Alternative disappearance models are also tested. The neutrino decay hypothesis is disfavored at 7.2{sigma} and the neutrino quantum decoherence hypothesis is disfavored at 9.0{sigma}.
Can the Super-Kamiokande Atmospheric Data Predict the Solar Neutrino Deficit ?
Ion Stancu
1999-03-31T23:59:59.000Z
In this Letter we show that the evidence for neutrino oscillations from the Super-Kamiokande atmospheric neutrino data fully determines the 3x3 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 R_e^{Solar} = 0.55, in good agreement with the experimental results. We achieve this result within the framework of a minimal, three-generations neutrino mixing, with mass squared differences of dM^2 = 0.45 eV^2 and dm^2 = O(10^-3) eV^2. The mixing matrix derived here is characterized by the mixing angles theta = 35.1, beta = 5.5, and psi = 23.3, and a vanishing CP-violating phase, delta = 0.
Neutrino Properties Before and After KamLAND
S. Pakvasa; J. W. F. Valle
2003-02-05T23:59:59.000Z
We review neutrino oscillation physics, including the determination of mass splittings and mixings from current solar, atmospheric, reactor and accelerator neutrino data. A brief discussion is given of cosmological and astrophysical implications. Non-oscillation phenomena such as neutrinoless double beta decay would, if discovered, probe the absolute scale of neutrino mass and also reveal their Majorana nature. Non-oscillation descriptions in terms of spin-flavor precession (SFP) and non-standard neutrino interactions (NSI) currently provide an excellent fit of the solar data. However they are at odds with the first results from the KamLAND experiment which imply that, despite their theoretical interest, non-standard mechanisms can only play a sub-leading role in the solar neutrino anomaly. Accepting the LMA-MSW solution, one can use the current solar neutrino data to place important restrictions on non-standard neutrino properties, such as neutrino magnetic moments. Both solar and atmospheric neutrino data can also be used to place constraints on neutrino instability as well as the more exotic possibility of $CPT$ and Lorentz Violation. Weillustrate the potential of future data from experiments such as KamLAND, Borexino and the upcoming neutrino factories in constraining non-standard neutrino properties.
New textures for the lepton mass matrices
P. M. Ferreira; L. Lavoura
2014-12-02T23:59:59.000Z
We study predictive textures for the lepton mass matrices in which the charged-lepton mass matrix has either four or five zero matrix elements while the neutrino Majorana mass matrix has, respectively, either four or three zero matrix elements. We find that all the viable textures of these two kinds share many predictions: the neutrino mass spectrum is inverted, the sum of the light-neutrino masses is close to 0.1 eV, the Dirac phase $\\delta$ in the lepton mixing matrix is close to either $0$ or $\\pi$, and the mass term responsible for neutrinoless double-beta decay lies in between 12 and 22 meV.
Neutrinos: Theory and Phenomenology
Parke, Stephen
2013-10-22T23:59:59.000Z
The theory and phenomenology of neutrinos will be addressed, especially that relating to the observation of neutrino flavor transformations. The current status and implications for future experiments will be discussed with special emphasis on the experiments that will determine the neutrino mass ordering, the dominant flavor content of the neutrino mass eigenstate with the smallest electron neutrino content and the size of CP violation in the neutrino sector. Beyond the neutrino Standard Model, the evidence for and a possible definitive experiment to confirm or refute the existence of light sterile neutrinos will be briefly discussed.
Solar Neutrinos and the Decaying Neutrino Hypothesis
Jeffrey M. Berryman; Andre de Gouvea; Daniel Hernandez
2014-11-02T23:59:59.000Z
We explore, mostly using data from solar neutrino experiments, the hypothesis that the neutrino mass eigenstates are unstable. We find that, by combining $^8$B solar neutrino data with those on $^7$Be and lower-energy solar neutrinos, one obtains a mostly model-independent bound on both the $\
An explicit SU(12) family and flavor unification model with natural fermion masses and mixings
Albright, Carl H. [Northern Illinois Univ., Dekalb, IL (United States); Feger, Robert P. [Vanderbilt Univ., Nashville, TN (United States); Kephart, Thomas W. [Vanderbilt Univ., Nashville, TN (United States)
2012-07-01T23:59:59.000Z
We present an SU(12) unification model with three light chiral families, avoiding any external flavor symmetries. The hierarchy of quark and lepton masses and mixings is explained by higher dimensional Yukawa interactions involving Higgs bosons that contain SU(5) singlet fields with VEVs about 50 times smaller than the SU(12) unification scale. The presented model has been analyzed in detail and found to be in very good agreement with the observed quark and lepton masses and mixings.
Giachero, A; Falferi, P; Faverzani, M; Ferri, E; Giordano, C; Maino, M; Margesin, B; Mezzena, R; Nizzolo, R; Nucciotti, A; Puiu, A; Zanetti, L
2015-01-01T23:59:59.000Z
The European Research Council has recently funded HOLMES, a project with the aim of performing a calorimetric measurement of the electron neutrino mass measuring the energy released in the electron capture decay of \\textsuperscript{163}Ho. The baseline for HOLMES are microcalorimeters coupled to Transition Edge Sensors (TESs) read out with rf-SQUIDs, for microwave multiplexing purposes. A promising alternative solution is based on superconducting microwave resonators, that have undergone rapid development in the last decade. These detectors, called MKIDs (Microwave Kinetic Inductance Detectors), are inherently multiplexed in the frequency domain and suitable for even larger-scale pixel arrays, with theoretical high energy resolution and fast response. The aim of our activity is to develop arrays of microresonator detectors for X-ray spectroscopy and suitable for the calorimetric measurement of the energy spectra of \\textsuperscript{163}Ho. Superconductive multilayer films composed by a sequence of pure Titani...
Dark matter and neutrino masses from a scale-invariant multi-Higgs portal
Karam, Alexandros
2015-01-01T23:59:59.000Z
We consider a classically scale invariant version of the Standard Model, extended by an extra dark $SU(2)_X$ gauge group. Apart from the dark gauge bosons and a dark scalar doublet which is coupled to the Standard Model Higgs through a portal coupling, we incorporate right-handed neutrinos and an additional real singlet scalar field. After symmetry breaking \\`{a} la Coleman-Weinberg, we examine the multi-Higgs sector and impose theoretical and experimental constraints. In addition, by computing the dark matter relic abundance and the spin-independent scattering cross section off a nucleon we determine the viable dark matter mass range in accordance with present limits. The model can be tested in the near future by collider experiments and direct detection searches such as XENON 1T.
Implications of theta_13 on Fritzsch-like lepton mass matrices
Fakay, Priyanka; Verma, Rohit; Ahuja, Gulsheen; Gupta, Manmohan
2013-01-01T23:59:59.000Z
Implications of the lepton mixing angles, in particular of theta_13, have been investigated for minimal as well as non-minimal Fritzsch-like textures for the case of Majorana neutrinos. Both, in minimal texture (texture 6 zero lepton mass matrices) and non-minimal textures (two cases of texture 5 zero lepton mass matrices), inverted hierarchy and degenerate scenario of neutrino masses have been ruled out. The implications of theta_13 have been investigated on the lightest neutrino mass m_\
Implications of theta_13 on Fritzsch-like lepton mass matrices
Priyanka Fakay; Samandeep Sharma; Rohit Verma; Gulsheen Ahuja; Manmohan Gupta
2013-01-25T23:59:59.000Z
Implications of the lepton mixing angles, in particular of theta_13, have been investigated for minimal as well as non-minimal Fritzsch-like textures for the case of Majorana neutrinos. Both, in minimal texture (texture 6 zero lepton mass matrices) and non-minimal textures (two cases of texture 5 zero lepton mass matrices), inverted hierarchy and degenerate scenario of neutrino masses have been ruled out. The implications of theta_13 have been investigated on the lightest neutrino mass m_\
Naturalness and the neutrino matrix
Sayre, J. [Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801 (United States); Wiesenfeldt, S. [Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801 (United States); Institut fur Theoretische Teilchenphysik, Universitaet Karlsruhe, 76128 Karlsruhe (Germany)
2008-03-01T23:59:59.000Z
The observed pattern of neutrino mass splittings and mixing angles indicates that their family structure is significantly different from that of the charged fermions. We investigate the implications of these data for the fermion mass matrices in grand-unified theories with a type-I seesaw mechanism. We show that, with simple assumptions, naturalness leads to a strongly hierarchical Majorana mass matrix for heavy right-handed neutrinos and a partially cascade form for the Dirac neutrino matrix. We consider various model building scenarios which could alter this conclusion, and discuss their consequences for the construction of a natural model. We find that including partially lopsided matrices can aid us in generating a satisfying model.
Minimal Seesaw Textures with Two Heavy Neutrinos
Srubabati Goswami; Atsushi Watanabe
2008-08-06T23:59:59.000Z
We systematically analyze the Dirac and the Majorana mass matrices in seesaw models with two heavy right-handed neutrinos. We perform thorough classification of the vanishing matrix elements which are compatible with the results from the current neutrino oscillation experiments. We include the possibility of a non-diagonal Majorana mass matrix which leads to new solutions viable with data. In a basis where the Majorana mass matrix is diagonal, these solutions imply a Dirac matrix with specific relationships amongst its elements. We find that at the level of total 4 zeros together in the Dirac and the Majorana sectors, the mass matrices are almost consistent with the data but one mixing angle is predicted to be unsuitable. At the next level, i.e. with total 3 zeros, only seven patterns of mass matrices describe the experimental data well. The seven solutions have testable predictions for the future neutrino experiments. In particular, each solution has definite predictions about the observation of the 1-3 leptonic mixing angle and the effective mass measured in neutrino-less double beta decay. The solutions of the mass matrices contain novel texture forms and provide new insights into the lepton-generation structure. We also discuss possible connections between these textures and the tri-bimaximal mixing to search for symmetry principles behind the mass matrix structure.
Sterile Neutrinos with Secret Interactions - Lasting Friendship with Cosmology
Chu, Xiaoyong; Kopp, Joachim
2015-01-01T23:59:59.000Z
Sterile neutrinos with mass ~1 eV and order 10% mixing with active neutrinos have been proposed as a solution to anomalies in neutrino oscillation data, but are tightly constrained by cosmological limits. It was recently shown that these constraints are avoided if sterile neutrinos couple to a new MeV-scale gauge boson A'. However, even this scenario is restricted by structure formation constraints when A'-mediated collisional processes lead to efficient active-to-sterile neutrino conversion after neutrinos have decoupled. In view of this, we reevaluate in this paper the viability of sterile neutrinos with such "secret" interactions. We carefully dissect their evolution in the early Universe, including the various production channels and the expected modifications to large scale structure formation. We argue that there are two regions in parameter space - one at very small A' coupling, one at relatively large A' coupling - where all constraints from big bang nucleosynthesis (BBN), cosmic microwave background ...
FEASIBILITY STUDY II OF A MUON BASED NEUTRINO SOURCE.
GALLARDO,J.C.; OZAKI,S.; PALMER,R.B.; ZISMAN,M.
2001-06-30T23:59:59.000Z
The concept of using a muon storage ring to provide a well characterized beam of muon and electron neutrinos (a Neutrino Factory) has been under study for a number of years now at various laboratories throughout the world. The physics program of a Neutrino Factoryis focused on the relatively unexplored neutrino sector. In conjunction with a detector located a suitable distance from the neutrino source, the facility would make valuable contributions to the study of neutrino masses and lepton mixing. A Neutrino Factory is expected to improve the measurement accuracy of sin{sup 2}(2{theta}{sub 23}) and {Delta}m{sup 2}{sub 32} and provide measurements of sin{sup 2}(2{theta}{sub 13}) and the sign of {Delta}m{sup 2}{sub 32}. It may also be able to measure CP violation in the lepton sector.
McKeown, R D
2014-01-01T23:59:59.000Z
Since the discovery of nuclear beta decay, nuclear physicists have studied the weak interaction and the nature of neutrinos. Many recent and current experiments have been focused on the elucidation of neutrino oscillations and neutrino mass. The quest for the absolute value of neutrino mass continues with higher precision studies of the tritium beta decay spectrum near the endpoint. Neutrino oscillations are studied through measurements of reactor neutrinos as a function of baseline and energy. And experiments searching for neutrinoless double beta decay seek to discover violation of lepton number and establish the Majorana nature of neutrino masses.
Neutrino Oscillation Effects on Supernova Light Element Synthesis
T. Yoshida; T. Kajino; H. Yokomakura; K. Kimura; A. Takamura; D. H. Hartmann
2006-06-02T23:59:59.000Z
Neutrino oscillations affect light element synthesis through the neutrino-process in supernova explosions. The 7Li and 11B yields produced in a supernova explosion of a 16.2 solar-mass star model increase by factors of 1.9 and 1.3 in the case of large mixing angle solution with normal mass hierarchy and sin^{2}2theta_{13} > 0.002 compared with those without the oscillations. In the case of inverted mass hierarchy or nonadiabatic 13-mixing resonance, the increment of their yields is much smaller. Neutrino oscillations raise the reaction rates of charged-current neutrino-process reactions in the region outside oxygen-rich layers. The number ratio of 7Li/11B could be a tracer of normal mass hierarchy and relatively large theta_{13}, still satisfying sin^{2}2theta_{13} < 0.1, through future precise observations in stars having strong supernova component.
Heavy Sterile Neutrinos and Neutrinoless Double Beta Decay
Manimala Mitra; Goran Senjanovic; Francesco Vissani
2012-05-17T23:59:59.000Z
Sterile neutrinos of mass up to a few tens of TeV can saturate the present experimental bound of neutrinoless double beta decay process. Due to the updated nuclear matrix elements, the bound on mass and mixing angle is now improved by one order of magnitude. We have performed a detailed analysis of neutrinoless double beta decay for the minimal Type I seesaw scenario. We have shown that in spite of the naive expectation that the light neutrinos give the dominant contribution, sterile neutrinos can saturate the present experimental bound of neutrinoless double beta decay process. However, in order to be consistent with radiative stability of light neutrino masses, the mass scale of sterile neutrinos should be less than 10 GeV.
Pseudo-Dirac neutrinos in the new standard model
Gouvea, Andre de; Huang, W.-C.; Jenkins, James [Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208 (United States); Elementary Particles and Field Theory Group, MS B285, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208 (United States)
2009-10-01T23:59:59.000Z
The addition of gauge-singlet fermions to the standard model Lagrangian renders the neutrinos massive and allows one to explain all that is experimentally known about neutrino masses and lepton mixing by varying the values of the Majorana mass parameters M for the gauge singlets and the neutrino Yukawa couplings {lambda}. Here we explore the region of parameter space where M values are much smaller than the neutrino Dirac masses {lambda}v. In this region, neutrinos are pseudo-Dirac fermions. We find that current solar data constrain M values to be less than at least 10{sup -9} eV, and discuss the sensitivity of future experiments to tiny gauge-singlet fermion masses. We also discuss a useful basis for analyzing pseudo-Dirac neutrino mixing effects. In particular, we identify a simple relationship between elements of M and the induced enlarged mixing matrix and new mass-squared differences. These allow one to directly relate bounds on the new mass-squared differences to bounds on the singlet fermion Majorana masses.
Neutrino mass mechanisms in 3-3-1 models: A short review
C. A. de S. Pires
2014-12-03T23:59:59.000Z
In this paper we review some mechanisms that provide light neutrinos in the framework of 3-3-1 gauge models without exotic leptons. In regard to the minimal 3-3-1 model, we call the attention to the fact that the perturbative regime of the model goes until 5 TeV. This requires alternative mechanisms in order to generate light neutrinos. In this review we discuss two mechanisms capable of generating light neutrinos in the framework of the minimal 3-3-1 model. In regard to the 3-3-1 model with right-handed neutrinos, we call the attention to the fact that in it mechanisms that generate light left-handed neutrinos also generate light right-handed neutrinos. Finally, we call the attention to the fact that the 3-3-1 model with right-handed neutrinos accommodate naturally the inverse seesaw mechanism.
A study of muon neutrino disappearance in the MINOS detectors and the NuMI beam
Ling, Jiajie; /South Carolina U.
2010-07-01T23:59:59.000Z
There is now substantial evidence that the proper description of neutrino involves two representations related by the 3 x 3 PMNS matrix characterized by either distinct mass or flavor. The parameters of this mixing matrix, three angles and a phase, as well as the mass differences between the three mass eigenstates must be determined experimentally. The Main Injector Neutrino Oscillation Search experiment is designed to study the flavor composition of a beam of muon neutrinos as it travels between the Near Detector at Fermi National Accelerator Laboratory at 1 km from the target, and the Far Detector in the Soudan iron mine in Minnesota at 735 km from the target. From the comparison of reconstructed neutrino energy spectra at the near and far location, precise measurements of neutrino oscillation parameters from muon neutrino disappearance and electron neutrino appearance are expected. It is very important to know the neutrino flux coming from the source in order to achieve the main goal of the MINOS experiment: precise measurements of the atmospheric mass splitting |{Delta}m{sub 23}{sup 2}|, sin{sup 2} {theta}{sub 23}. The goal of my thesis is to accurately predict the neutrino flux for the MINOS experiment and measure the neutrino mixing angle and atmospheric mass splitting.
Low-mass helium star models for type Ib supernovae - Light curves, mixing, and nucleosynthesis
Shigeyama, Toshikazu; Nomoto, Kenichi; Tsujimoto, Takuji; Hashimoto, Masaki (Tokyo Univ. (Japan) Kyushu Univ., Fukuoka (Japan))
1990-09-01T23:59:59.000Z
The applicability of theoretical models of He-star explosions to type Ib SN explosions is explored. Particular attention is given to light curves and mixing, Rayleigh-Taylor instabilities and mixing, and nucleosynthesis and the mass of Ni-56. Typical numerical results are presented in graphs, and it is concluded that the explosions of SN 1983N and SN 1983I can be accurately represented in terms of explosions of He stars with M(alpha) of 3-4 solar mass. A strong M(alpha) dependence of light-curve shape, photospheric velocity, and Ni-56 mass is found. 44 refs.
Noncommutative spectral geometry, Bogoliubov transformations and neutrino oscillations
Gargiulo, Maria Vittoria; Vitiello, Giuseppe
2015-01-01T23:59:59.000Z
In this report we show that neutrino mixing is intrinsically contained in Connes' noncommutative spectral geometry construction, thanks to the introduction of the doubling of algebra, which is connected to the Bogoliubov transformation. It is known indeed that these transformations are responsible for the mixing, turning the mass vacuum state into the flavor vacuum state, in such a way that mass and flavor vacuum states are not unitary equivalent. There is thus a red thread that binds the doubling of algebra of Connes' model to the neutrino mixing.
Noncommutative spectral geometry, Bogoliubov transformations and neutrino oscillations
Maria Vittoria Gargiulo; Mairi Sakellariadou; Giuseppe Vitiello
2015-02-10T23:59:59.000Z
In this report we show that neutrino mixing is intrinsically contained in Connes' noncommutative spectral geometry construction, thanks to the introduction of the doubling of algebra, which is connected to the Bogoliubov transformation. It is known indeed that these transformations are responsible for the mixing, turning the mass vacuum state into the flavor vacuum state, in such a way that mass and flavor vacuum states are not unitary equivalent. There is thus a red thread that binds the doubling of algebra of Connes' model to the neutrino mixing.
Monreal, Benjamin
2009-01-01T23:59:59.000Z
The shape of the beta decay energy distribution is sensitive to the mass of the electron neutrino. Attempts to measure the endpoint shape of tritium decay have so far seen no distortion from the zero-mass form, thus placing an upper limit of m_nu_beta < 2.3 eV. Here we show that a new type of electron energy spectroscopy could improve future measurements of this spectrum and therefore of the neutrino mass. We propose to detect the coherent cyclotron radiation emitted by an energetic electron in a magnetic field. For mildly relativistic electrons, like those in tritium decay, the relativistic shift of the cyclotron frequency allows us to extract the electron energy from the emitted radiation. We present calculations for the energy resolution, noise limits, high-rate measurement capability, and systematic errors expected in such an experiment.
Benjamin Monreal; Joseph A. Formaggio
2009-04-18T23:59:59.000Z
The shape of the beta decay energy distribution is sensitive to the mass of the electron neutrino. Attempts to measure the endpoint shape of tritium decay have so far seen no distortion from the zero-mass form, thus placing an upper limit of m_nu_beta < 2.3 eV. Here we show that a new type of electron energy spectroscopy could improve future measurements of this spectrum and therefore of the neutrino mass. We propose to detect the coherent cyclotron radiation emitted by an energetic electron in a magnetic field. For mildly relativistic electrons, like those in tritium decay, the relativistic shift of the cyclotron frequency allows us to extract the electron energy from the emitted radiation. We present calculations for the energy resolution, noise limits, high-rate measurement capability, and systematic errors expected in such an experiment.
Alpert, B; Bennett, D; Biasotti, M; Boragno, C; Brofferio, C; Ceriale, V; Corsini, D; De Gerone, M; Dressler, R; Faverzani, M; Ferri, E; Fowler, J; Gatti, F; Giachero, A; Hays-Wehle, J; Heinitz, S; Hilton, G; Koester, U; Lusignoli, M; Maino, M; Mates, J; Nisi, S; Nizzolo, R; Nucciotti, A; Pessina, G; Pizzigoni, G; Puiu, A; Ragazzi, S; Reintsema, C; Gomes, M Ribeiro; Schmidt, D; Schumann, D; Sisti, M; Swetz, D; Terranova, F; Ullom, J
2014-01-01T23:59:59.000Z
The European Research Council has recently funded HOLMES, a new experiment to directly measure the neutrino mass. HOLMES will perform a calorimetric measurement of the energy released in the decay of 163Ho. The calorimetric measurement eliminates systematic uncertainties arising from the use of external beta sources, as in experiments with beta spectrometers. This measurement was proposed in 1982 by A. De Rujula and M. Lusignoli, but only recently the detector technological progress allowed to design a sensitive experiment. HOLMES will deploy a large array of low temperature microcalorimeters with implanted 163Ho nuclei. The resulting mass sensitivity will be as low as 0.4 eV. HOLMES will be an important step forward in the direct neutrino mass measurement with a calorimetric approach as an alternative to spectrometry. It will also establish the potential of this approach to extend the sensitivity down to 0.1 eV. We outline here the project with its technical challenges and perspectives.
B. Alpert; M. Balata; D. Bennett; M. Biasotti; C. Boragno; C. Brofferio; V. Ceriale; D. Corsini; P. K. Day; M. De Gerone; R. Dressler; M. Faverzani; E. Ferri; J. Fowler; F. Gatti; A. Giachero; J. Hays-Wehle; S. Heinitz; G. Hilton; U. Koester; M. Lusignoli; M. Maino; J. Mates; S. Nisi; R. Nizzolo; A. Nucciotti; G. Pessina; G. Pizzigoni; A. Puiu; S. Ragazzi; C. Reintsema; M. Ribeiro Gomes; D. Schmidt; D. Schumann; M. Sisti; D. Swetz; F. Terranova; J. Ullom
2015-03-17T23:59:59.000Z
The European Research Council has recently funded HOLMES, a new experiment to directly measure the neutrino mass. HOLMES will perform a calorimetric measurement of the energy released in the decay of 163Ho. The calorimetric measurement eliminates systematic uncertainties arising from the use of external beta sources, as in experiments with beta spectrometers. This measurement was proposed in 1982 by A. De Rujula and M. Lusignoli, but only recently the detector technological progress allowed to design a sensitive experiment. HOLMES will deploy a large array of low temperature microcalorimeters with implanted 163Ho nuclei. The resulting mass sensitivity will be as low as 0.4 eV. HOLMES will be an important step forward in the direct neutrino mass measurement with a calorimetric approach as an alternative to spectrometry. It will also establish the potential of this approach to extend the sensitivity down to 0.1 eV. We outline here the project with its technical challenges and perspectives.
Neutrino-antineutrino correlations in dense anisotropic media
Julien Serreau; Cristina Volpe
2015-01-08T23:59:59.000Z
We derive the most general evolution equations describing in-medium (anti)neutrino propagation in the mean-field approximation. In particular, we consider various types of neutrino-antineutrino mixing, for both Dirac and Majorana fields, resulting either from nontrivial pair correlations or from helicity coherence due to the nonvanishing neutrino masses. We show that, unless the medium is spatially homogeneous and isotropic, these correlations are sourced by the usual neutrino and antineutrino densities. This may be of importance in astrophysical environments such as core-collapse supernovae.
Neutrino Oscillation Physics Potential of the T2K Experiment
Abe, K; Aihara, H; Akiri, T; Andreopoulos, C; Aoki, S; Ariga, A; Assylbekov, S; Autiero, D; Barbi, M; Barker, G J; Barr, G; Bass, M; Batkiewicz, M; Bay, F; Berardi, V; Berger, B E; Berkman, S; Bhadra, S; Blaszczyk, F d M; Blondel, A; Bojechko, C; Bordoni, S; Boyd, S B; Brailsford, D; Bravar, A; Bronner, C; Buchanan, N; Calland, R G; Rodr'iguez, J Caravaca; Cartwright, S L; Castillo, R; Catanesi, M G; Cervera, A; Cherdack, D; Christodoulou, G; Clifton, A; Coleman, J; Coleman, S J; Collazuol, G; Connolly, K; Cremonesi, L; Dabrowska, A; Danko, I; Das, R; Davis, S; de Perio, P; De Rosa, G; Dealtry, T; Dennis, S R; Densham, C; Dewhurst, D; Di Lodovico, F; Di Luise, S; Drapier, O; Duboyski, T; Duffy, K; Dumarchez, J; Dytman, S; Dziewiecki, M; Emery-Schrenk, S; Ereditato, A; Escudero, L; Finch, A J; Friend, M; Fujii, Y; Fukuda, Y; Furmanski, A P; Galymov, V; Giffin, S; Giganti, C; Gilje, K; Goeldi, D; Golan, T; Gonin, M; Grant, N; Gudin, D; Hadley, D R; Haesler, A; Haigh, M D; Hamilton, P; Hansen, D; Hara, T; Hartz, M; Hasegawa, T; Hastings, N C; Hayato, Y; Hearty, C; Helmer, R L; Hierholzer, M; Hignight, J; Hillairet, A; Himmel, A; Hiraki, T; Hirota, S; Holeczek, J; Horikawa, S; Huang, K; Ichikawa, A K; Ieki, K; Ieva, M; Ikeda, M; Imber, J; Insler, J; Irvine, T J; Ishida, T; Ishii, T; Iwai, E; Iwamoto, K; Iyogi, K; Izmaylov, A; Jacob, A; Jamieson, B; Johnson, R A; Johnson, S; Jo, J H; Jonsson, P; Jung, C K; Kabirnezhad, M; Kaboth, A C; Kajita, T; Kakuno, H; Kameda, J; Kanazawa, Y; Karlen, D; Karpikov, I; Katori, T; Kearns, E; Khabibullin, M; Khotjantsev, A; Kielczewska, D; Kikawa, T; Kilinski, A; Kim, J; King, S; Kisiel, J; Kitching, P; Kobayashi, T; Koch, L; Kolaceke, A; Konaka, A; Kormos, L L; Korzenev, A; Koseki, K; Koshio, Y; Kropp, W; Kubo, H; Kudenko, Y; Kurjata, R; Kutter, T; Lagoda, J; Laihem, K; Lamont, I; Larkin, E; Laveder, M; Lawe, M; Lazos, M; Lindner, T; Lister, C; Litchfield, R P; Longhin, A; Ludovici, L; Magaletti, L; Mahn, K; Malek, M; Manly, S; Marino, A D; Marteau, J; Martin, J F; Martynenko, S; Maruyama, T; Matveev, V; Mavrokoridis, K; Mazzucato, E; McCarthy, M; McCauley, N; McFarland, K S; McGrew, C; Mefodiev, A; Metelko, C; Mezzetto, M; Mijakowski, P; Miller, C A; Minamino, A; Mineev, O; Missert, A; Miura, M; Moriyama, S; Mueller, Th A; Murakami, A; Murdoch, M; Murphy, S; Myslik, J; Nakadaira, T; Nakahata, M; Nakamura, K; Nakayama, S; Nakaya, T; Nakayoshi, K; Nielsen, C; Nirkko, M; Nishikawa, K; Nishimura, Y; O'Keeffe, H M; Ohta, R; Okumura, K; Okusawa, T; Oryszczak, W; Oser, S M; Ovsyannikova, T; Owen, R A; Oyama, Y; Palladino, V; Palomino, J L; Paolone, V; Payne, D; Perevozchikov, O; Perkin, J D; Petrov, Y; Pickard, L; Guerra, E S Pinzon; Pistillo, C; Plonski, P; Poplawska, E; Popov, B; Posiadala-Zezula, M; Poutissou, J -M; Poutissou, R; Przewlocki, P; Quilain, B; Radicioni, E; Ratoff, P N; Ravonel, M; Rayner, M A M; Redij, A; Reeves, M; Reinherz-Aronis, E; Riccio, C; Rodrigues, P A; Rojas, P; Rondio, E; Roth, S; Rubbia, A; Ruterbories, D; Sacco, R; Sakashita, K; S'anchez, F; Sato, F; Scantamburlo, E; Scholberg, K; Schoppmann, S; Schwehr, J; Scott, M; Seiya, Y; Sekiguchi, T; Sekiya, H; Sgalaberna, D; Shaker, F; Shiozawa, M; Short, S; Shustrov, Y; Sinclair, P; Smith, B; Smy, M; Sobczyk, J T; Sobel, H; Sorel, M; Southwell, L; Stamoulis, P; Steinmann, J; Still, B; Suda, Y; Suzuki, A; Suzuki, K; Suzuki, S Y; Suzuki, Y; Tacik, R; Tada, M; Takahashi, S; Takeda, A; Takeuchi, Y; Tanaka, H K; Tanaka, H A; Tanaka, M M; Terhorst, D; Terri, R; Thompson, L F; Thorley, A; Tobayama, S; Toki, W; Tomura, T; Totsuka, Y; Touramanis, C; Tsukamoto, T; Tzanov, M; Uchida, Y; Vacheret, A; Vagins, M; Vasseur, G; Wachala, T; Waldron, A V; Walter, C W; Wark, D; Wascko, M O; Weber, A; Wendell, R; Wilkes, R J; Wilking, M J; Wilkinson, C; Williamson, Z; Wilson, J R; Wilson, R J; Wongjirad, T; Yamada, Y; Yamamoto, K; Yanagisawa, C; Yano, T; Yen, S; Yershov, N; Yokoyama, M; Yuan, T; Yu, M; Zalewska, A; Zalipska, J; Zambelli, L; Zaremba, K; Ziembicki, M; Zimmerman, E D; Zito, M; Zmuda, J
2014-01-01T23:59:59.000Z
The observation of the recent electron neutrino appearance in a muon neutrino beam and the high-precision measurement of the mixing angle $\\theta_{13}$ have led to a re-evaluation of the physics potential of the T2K long-baseline neutrino oscillation experiment. Sensitivities are explored for CP violation in neutrinos, non-maximal $\\sin^22\\theta_{23}$, the octant of $\\theta_{23}$, and the mass hierarchy, in addition to the measurements of $\\delta_{CP}$, $\\sin^2\\theta_{23}$, and $\\Delta m^2_{32}$, for various combinations of $\
Neutrino Oscillation Physics Potential of the T2K Experiment
K. Abe; J. Adam; H. Aihara; T. Akiri; C. Andreopoulos; S. Aoki; A. Ariga; S. Assylbekov; D. Autiero; M. Barbi; G. J. Barker; G. Barr; P. Bartet-Friburg; M. Bass; M. Batkiewicz; F. Bay; V. Berardi; B. E. Berger; S. Berkman; S. Bhadra; F. d. M. Blaszczyk; A. Blondel; C. Bojechko; S. Bordoni; S. B. Boyd; D. Brailsford; A. Bravar; C. Bronner; N. Buchanan; R. G. Calland; J. Caravaca Rodr'iguez; S. L. Cartwright; R. Castillo; M. G. Catanesi; A. Cervera; D. Cherdack; G. Christodoulou; A. Clifton; J. Coleman; S. J. Coleman; G. Collazuol; K. Connolly; L. Cremonesi; A. Dabrowska; I. Danko; R. Das; S. Davis; P. de Perio; G. De Rosa; T. Dealtry; S. R. Dennis; C. Densham; D. Dewhurst; F. Di Lodovico; S. Di Luise; O. Drapier; T. Duboyski; K. Duffy; J. Dumarchez; S. Dytman; M. Dziewiecki; S. Emery-Schrenk; A. Ereditato; L. Escudero; T. Feusels; A. J. Finch; G. A. Fiorentini; M. Friend; Y. Fujii; Y. Fukuda; A. P. Furmanski; V. Galymov; A. Garcia; S. Giffin; C. Giganti; K. Gilje; D. Goeldi; T. Golan; M. Gonin; N. Grant; D. Gudin; D. R. Hadley; L. Haegel; A. Haesler; M. D. Haigh; P. Hamilton; D. Hansen; T. Hara; M. Hartz; T. Hasegawa; N. C. Hastings; T. Hayashino; Y. Hayato; C. Hearty; R. L. Helmer; M. Hierholzer; J. Hignight; A. Hillairet; A. Himmel; T. Hiraki; S. Hirota; J. Holeczek; S. Horikawa; K. Huang; A. K. Ichikawa; K. Ieki; M. Ieva; M. Ikeda; J. Imber; J. Insler; T. J. Irvine; T. Ishida; T. Ishii; E. Iwai; K. Iwamoto; K. Iyogi; A. Izmaylov; A. Jacob; B. Jamieson; R. A. Johnson; S. Johnson; J. H. Jo; P. Jonsson; C. K. Jung; M. Kabirnezhad; A. C. Kaboth; T. Kajita; H. Kakuno; J. Kameda; Y. Kanazawa; D. Karlen; I. Karpikov; T. Katori; E. Kearns; M. Khabibullin; A. Khotjantsev; D. Kielczewska; T. Kikawa; A. Kilinski; J. Kim; S. King; J. Kisiel; P. Kitching; T. Kobayashi; L. Koch; T. Koga; A. Kolaceke; A. Konaka; L. L. Kormos; A. Korzenev; Y. Koshio; W. Kropp; H. Kubo; Y. Kudenko; R. Kurjata; T. Kutter; J. Lagoda; K. Laihem; I. Lamont; E. Larkin; M. Laveder; M. Lawe; M. Lazos; T. Lindner; C. Lister; R. P. Litchfield; A. Longhin; J. P. Lopez; L. Ludovici; L. Magaletti; K. Mahn; M. Malek; S. Manly; A. D. Marino; J. Marteau; J. F. Martin; P. Martins; S. Martynenko; T. Maruyama; V. Matveev; K. Mavrokoridis; E. Mazzucato; M. McCarthy; N. McCauley; K. S. McFarland; C. McGrew; A. Mefodiev; C. Metelko; M. Mezzetto; P. Mijakowski; C. A. Miller; A. Minamino; O. Mineev; A. Missert; M. Miura; S. Moriyama; Th. A. Mueller; A. Murakami; M. Murdoch; S. Murphy; J. Myslik; T. Nakadaira; M. Nakahata; K. G. Nakamura; K. Nakamura; S. Nakayama; T. Nakaya; K. Nakayoshi; C. Nantais; C. Nielsen; M. Nirkko; K. Nishikawa; Y. Nishimura; J. Nowak; H. M. O'Keeffe; R. Ohta; K. Okumura; T. Okusawa; W. Oryszczak; S. M. Oser; T. Ovsyannikova; R. A. Owen; Y. Oyama; V. Palladino; J. L. Palomino; V. Paolone; D. Payne; O. Perevozchikov; J. D. Perkin; Y. Petrov; L. Pickard; E. S. Pinzon Guerra; C. Pistillo; P. Plonski; E. Poplawska; B. Popov; M. Posiadala-Zezula; J. -M. Poutissou; R. Poutissou; P. Przewlocki; B. Quilain; E. Radicioni; P. N. Ratoff; M. Ravonel; M. A. M. Rayner; A. Redij; M. Reeves; E. Reinherz-Aronis; C. Riccio; P. A. Rodrigues; P. Rojas; E. Rondio; S. Roth; A. Rubbia; D. Ruterbories; R. Sacco; K. Sakashita; F. S'anchez; F. Sato; E. Scantamburlo; K. Scholberg; S. Schoppmann; J. Schwehr; M. Scott; Y. Seiya; T. Sekiguchi; H. Sekiya; D. Sgalaberna; R. Shah; F. Shaker; M. Shiozawa; S. Short; Y. Shustrov; P. Sinclair; B. Smith; M. Smy; J. T. Sobczyk; H. Sobel; M. Sorel; L. Southwell; P. Stamoulis; J. Steinmann; B. Still; Y. Suda; A. Suzuki; K. Suzuki; S. Y. Suzuki; Y. Suzuki; R. Tacik; M. Tada; S. Takahashi; A. Takeda; Y. Takeuchi; H. K. Tanaka; H. A. Tanaka; M. M. Tanaka; D. Terhorst; R. Terri; L. F. Thompson; A. Thorley; S. Tobayama; W. Toki; T. Tomura; Y. Totsuka; C. Touramanis; T. Tsukamoto; M. Tzanov; Y. Uchida; A. Vacheret; M. Vagins; G. Vasseur; T. Wachala; A. V. Waldron; K. Wakamatsu; C. W. Walter; D. Wark; W. Warzycha; M. O. Wascko; A. Weber; R. Wendell; R. J. Wilkes; M. J. Wilking; C. Wilkinson; Z. Williamson; J. R. Wilson; R. J. Wilson; T. Wongjirad; Y. Yamada; K. Yamamoto; C. Yanagisawa; T. Yano; S. Yen; N. Yershov; M. Yokoyama; K. Yoshida; T. Yuan; M. Yu; A. Zalewska; J. Zalipska; L. Zambelli; K. Zaremba; M. Ziembicki; E. D. Zimmerman; M. Zito; J. Zmuda
2015-02-10T23:59:59.000Z
The observation of the recent electron neutrino appearance in a muon neutrino beam and the high-precision measurement of the mixing angle $\\theta_{13}$ have led to a re-evaluation of the physics potential of the T2K long-baseline neutrino oscillation experiment. Sensitivities are explored for CP violation in neutrinos, non-maximal $\\sin^22\\theta_{23}$, the octant of $\\theta_{23}$, and the mass hierarchy, in addition to the measurements of $\\delta_{CP}$, $\\sin^2\\theta_{23}$, and $\\Delta m^2_{32}$, for various combinations of $\
The Intermediate Neutrino Program
C. Adams; J. R. Alonso; A. M. Ankowski; J. A. Asaadi; J. Ashenfelter; S. N. Axani; K. Babu; C. Backhouse; H. R. Band; P. S. Barbeau; N. Barros; A. Bernstein; M. Betancourt; M. Bishai; E. Blucher; J. Bouffard; N. Bowden; S. Brice; C. Bryan; L. Camilleri; J. Cao; J. Carlson; R. E. Carr; A. Chatterjee; M. Chen; S. Chen; M. Chiu; E. D. Church; J. I. Collar; G. Collin; J. M. Conrad; M. R. Convery; R. L. Cooper; D. Cowen; H. Davoudiasl; A. De Gouvea; D. J. Dean; G. Deichert; F. Descamps; T. DeYoung; M. V. Diwan; Z. Djurcic; M. J. Dolinski; J. Dolph; B. Donnelly; D. A. Dwyer; S. Dytman; Y. Efremenko; L. L. Everett; A. Fava; E. Figueroa-Feliciano; B. Fleming; A. Friedland; B. K. Fujikawa; T. K. Gaisser; M. Galeazzi; D. C. Galehouse; A. Galindo-Uribarri; G. T. Garvey; S. Gautam; K. E. Gilje; M. Gonzalez-Garcia; M. C. Goodman; H. Gordon; E. Gramellini; M. P. Green; A. Guglielmi; R. W. Hackenburg; A. Hackenburg; F. Halzen; K. Han; S. Hans; D. Harris; K. M. Heeger; M. Herman; R. Hill; A. Holin; P. Huber; D. E. Jaffe; R. A. Johnson; J. Joshi; G. Karagiorgi; L. J. Kaufman; B. Kayser; S. H. Kettell; B. J. Kirby; J. R. Klein; Yu. G. Kolomensky; R. M. Kriske; C. E. Lane; T. J. Langford; A. Lankford; K. Lau; J. G. Learned; J. Ling; J. M. Link; D. Lissauer; L. Littenberg; B. R. Littlejohn; S. Lockwitz; M. Lokajicek; W. C. Louis; K. Luk; J. Lykken; W. J. Marciano; J. Maricic; D. M. Markoff; D. A. Martinez Caicedo; C. Mauger; K. Mavrokoridis; E. McCluskey; D. McKeen; R. McKeown; G. Mills; I. Mocioiu; B. Monreal; M. R. Mooney; J. G. Morfin; P. Mumm; J. Napolitano; R. Neilson; J. K. Nelson; M. Nessi; D. Norcini; F. Nova; D. R. Nygren; G. D. Orebi Gann; O. Palamara; Z. Parsa; R. Patterson; P. Paul; A. Pocar; X. Qian; J. L. Raaf; R. Rameika; G. Ranucci; H. Ray; D. Reyna; G. C. Rich; P. Rodrigues; E. Romero Romero; R. Rosero; S. D. Rountree; B. Rybolt; M. C. Sanchez; G. Santucci; D. Schmitz; K. Scholberg; D. Seckel; M. Shaevitz; R. Shrock; M. B. Smy; M. Soderberg; A. Sonzogni; A. B. Sousa; J. Spitz; J. M. St. John; J. Stewart; J. B. Strait; G. Sullivan; R. Svoboda; A. M. Szelc; R. Tayloe; M. A. Thomson; M. Toups; A. Vacheret; M. Vagins; R. G. Van de Water; R. B. Vogelaar; M. Weber; W. Weng; M. Wetstein; C. White; B. R. White; L. Whitehead; D. W. Whittington; M. J. Wilking; R. J. Wilson; P. Wilson; D. Winklehner; D. R. Winn; E. Worcester; L. Yang; M. Yeh; Z. W. Yokley; J. Yoo; B. Yu; J. Yu; C. Zhang
2015-04-01T23:59:59.000Z
The US neutrino community gathered at the Workshop on the Intermediate Neutrino Program (WINP) at Brookhaven National Laboratory February 4-6, 2015 to explore opportunities in neutrino physics over the next five to ten years. Scientists from particle, astroparticle and nuclear physics participated in the workshop. The workshop examined promising opportunities for neutrino physics in the intermediate term, including possible new small to mid-scale experiments, US contributions to large experiments, upgrades to existing experiments, R&D plans and theory. The workshop was organized into two sets of parallel working group sessions, divided by physics topics and technology. Physics working groups covered topics on Sterile Neutrinos, Neutrino Mixing, Neutrino Interactions, Neutrino Properties and Astrophysical Neutrinos. Technology sessions were organized into Theory, Short-Baseline Accelerator Neutrinos, Reactor Neutrinos, Detector R&D and Source, Cyclotron and Meson Decay at Rest sessions.This report summarizes discussion and conclusions from the workshop.
The Intermediate Neutrino Program
Adams, C; Ankowski, A M; Asaadi, J A; Ashenfelter, J; Axani, S N; Babu, K; Backhouse, C; Band, H R; Barbeau, P S; Barros, N; Bernstein, A; Betancourt, M; Bishai, M; Blucher, E; Bouffard, J; Bowden, N; Brice, S; Bryan, C; Camilleri, L; Cao, J; Carlson, J; Carr, R E; Chatterjee, A; Chen, M; Chen, S; Chiu, M; Church, E D; Collar, J I; Collin, G; Conrad, J M; Convery, M R; Cooper, R L; Cowen, D; Davoudiasl, H; De Gouvea, A; Dean, D J; Deichert, G; Descamps, F; DeYoung, T; Diwan, M V; Djurcic, Z; Dolinski, M J; Dolph, J; Donnelly, B; Dwyer, D A; Dytman, S; Efremenko, Y; Everett, L L; Fava, A; Figueroa-Feliciano, E; Fleming, B; Friedland, A; Fujikawa, B K; Gaisser, T K; Galeazzi, M; Galehouse, D C; Galindo-Uribarri, A; Garvey, G T; Gautam, S; Gilje, K E; Gonzalez-Garcia, M; Goodman, M C; Gordon, H; Gramellini, E; Green, M P; Guglielmi, A; Hackenburg, R W; Hackenburg, A; Halzen, F; Han, K; Hans, S; Harris, D; Heeger, K M; Herman, M; Hill, R; Holin, A; Huber, P; Jaffe, D E; Johnson, R A; Joshi, J; Karagiorgi, G; Kaufman, L J; Kayser, B; Kettell, S H; Kirby, B J; Klein, J R; Kolomensky, Yu G; Kriske, R M; Lane, C E; Langford, T J; Lankford, A; Lau, K; Learned, J G; Ling, J; Link, J M; Lissauer, D; Littenberg, L; Littlejohn, B R; Lockwitz, S; Lokajicek, M; Louis, W C; Luk, K; Lykken, J; Marciano, W J; Maricic, J; Markoff, D M; Caicedo, D A Martinez; Mauger, C; Mavrokoridis, K; McCluskey, E; McKeen, D; McKeown, R; Mills, G; Mocioiu, I; Monreal, B; Mooney, M R; Morfin, J G; Mumm, P; Napolitano, J; Neilson, R; Nelson, J K; Nessi, M; Norcini, D; Nova, F; Nygren, D R; Gann, G D Orebi; Palamara, O; Parsa, Z; Patterson, R; Paul, P; Pocar, A; Qian, X; Raaf, J L; Rameika, R; Ranucci, G; Ray, H; Reyna, D; Rich, G C; Rodrigues, P; Romero, E Romero; Rosero, R; Rountree, S D; Rybolt, B; Sanchez, M C; Santucci, G; Schmitz, D; Scholberg, K; Seckel, D; Shaevitz, M; Shrock, R; Smy, M B; Soderberg, M; Sonzogni, A; Sousa, A B; Spitz, J; John, J M St; Stewart, J; Strait, J B; Sullivan, G; Svoboda, R; Szelc, A M; Tayloe, R; Thomson, M A; Toups, M; Vacheret, A; Vagins, M; Van de Water, R G; Vogelaar, R B; Weber, M; Weng, W; Wetstein, M; White, C; White, B R; Whitehead, L; Whittington, D W; Wilking, M J; Wilson, R J; Wilson, P; Winklehner, D; Winn, D R; Worcester, E; Yang, L; Yeh, M; Yokley, Z W; Yoo, J; Yu, B; Yu, J; Zhang, C
2015-01-01T23:59:59.000Z
The US neutrino community gathered at the Workshop on the Intermediate Neutrino Program (WINP) at Brookhaven National Laboratory February 4-6, 2015 to explore opportunities in neutrino physics over the next five to ten years. Scientists from particle, astroparticle and nuclear physics participated in the workshop. The workshop examined promising opportunities for neutrino physics in the intermediate term, including possible new small to mid-scale experiments, US contributions to large experiments, upgrades to existing experiments, R&D plans and theory. The workshop was organized into two sets of parallel working group sessions, divided by physics topics and technology. Physics working groups covered topics on Sterile Neutrinos, Neutrino Mixing, Neutrino Interactions, Neutrino Properties and Astrophysical Neutrinos. Technology sessions were organized into Theory, Short-Baseline Accelerator Neutrinos, Reactor Neutrinos, Detector R&D and Source, Cyclotron and Meson Decay at Rest sessions.This report summ...
CUORE and beyond: bolometric techniques to explore inverted neutrino mass hierarchy
D. R. Artusa; F. T. Avignone III; O. Azzolini; M. Balata; T. I. Banks; G. Bari; J. Beeman; F. Bellini; A. Bersani; M. Biassoni; C. Brofferio; C. Bucci; X. Z. Cai; A. Camacho; L. Canonica; X. G. Cao; S. Capelli; L. Carbone; L. Cardani; M. Carrettoni; N. Casali; D. Chiesa; N. Chott; M. Clemenza; S. Copello; C. Cosmelli; O. Cremonesi; R. J. Creswick; I. Dafinei; A. Dally; V. Datskov; A. De Biasi; M. M. Deninno; S. Di Domizio; M. L. di Vacri; L. Ejzak; D. Q. Fang; H. A. Farach; M. Faverzani; G. Fernandes; E. Ferri; F. Ferroni; E. Fiorini; M. A. Franceschi; S. J. Freedman; B. K. Fujikawa; A. Giachero; L. Gironi; A. Giuliani; J. Goett; P. Gorla; C. Gotti; T. D. Gutierrez; E. E. Haller; K. Han; K. M. Heeger; R. Hennings-Yeomans; H. Z. Huang; R. Kadel; K. Kazkaz; G. Keppel; Yu. G. Kolomensky; Y. L. Li; C. Ligi; X. Liu; Y. G. Ma; C. Maiano; M. Maino; M. Martinez; R. H. Maruyama; Y. Mei; N. Moggi; S. Morganti; T. Napolitano; S. Nisi; C. Nones; E. B. Norman; A. Nucciotti; T. O'Donnell; F. Orio; D. Orlandi; J. L. Ouellet; M. Pallavicini; V. Palmieri; L. Pattavina; M. Pavan; M. Pedretti; G. Pessina; V. Pettinacci; G. Piperno; C. Pira; S. Pirro; E. Previtali; V. Rampazzo; C. Rosenfeld; C. Rusconi; E. Sala; S. Sangiorgio; N. D. Scielzo; M. Sisti; A. R. Smith; L. Taffarello; M. Tenconi; F. Terranova; W. D. Tian; C. Tomei; S. Trentalange; G. Ventura; M. Vignati; B. S. Wang; H. W. Wang; L. Wielgus; J. Wilson; L. A. Winslow; T. Wise; A. Woodcraft; L. Zanotti; C. Zarra; B. X. Zhu; S. Zucchelli
2014-07-04T23:59:59.000Z
The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will search for neutrinoless double beta decay of $^{130}$Te. With 741 kg of TeO$_2$ crystals and an excellent energy resolution of 5 keV (0.2%) at the region of interest, CUORE will be one of the most competitive neutrinoless double beta decay experiments on the horizon. With five years of live time, CUORE projected neutrinoless double beta decay half-life sensitivity is $1.6\\times 10^{26}$ y at $1\\sigma$ ($9.5\\times10^{25}$ y at the 90% confidence level), which corresponds to an upper limit on the effective Majorana mass in the range 40--100 meV (50--130 meV). Further background rejection with auxiliary light detector can significantly improve the search sensitivity and competitiveness of bolometric detectors to fully explore the inverted neutrino mass hierarchy with $^{130}$Te and possibly other double beta decay candidate nuclei.
Solar Neutrino Results from Super-Kamiokande
M. B. Smy; the Super-Kamiokande Collaboration
2002-02-08T23:59:59.000Z
Super-Kamiokande has measured the solar neutrino flux using elastic neutrino-electron scattering in water. The measured flux is $2.32\\pm0.03$(stat)$^{+0.08}_{-0.07}$(syst)$\\times10^6$/(cm$^2$s) based on the energy range of 5 to 20 MeV for the recoiling electron. The time-dependence and energy spectrum of the recoiling electrons were studied to search for two-neutrino oscillation signatures. The absence of either significant zenith angle flux variation or distortions of the recoil electron spectrum places strong constraints on neutrino mass difference and mixing. In combination with the flux measurement, two allowed regions at large mixing are found.
Flavour leptogenesis with tribimaximal mixings and beyond
H. Zeen Devi; Amal Kr Sarma; N. Nimai Singh
2009-11-12T23:59:59.000Z
We compute and compare the baryon asymmetry of the universe in thermal leptogenesis scenario with and without flavour effects for different neutrino mass models namely degenerate, inverted hierarchical and normal hierarchical models, with tribimaximal mixings and beyond. Considering three possible diagonal forms of Dirac neutrino mass matrices $m_{LR}$, the right-handed Majorana mass matrices $M_{RR}$ are constructed from the light neutrino mass matrices $m_{LL}$ through the inverse seesaw formula. The normal hierarchical model is found to give the best predictions of the baryon asymmetry for both cases. This analysis serves as an additional information in the discrimination of the presently available neutrino mass models. Moreover, the flavour effects is found to give enhancement of the baryon asymmetry in thermal leptogenesis.
Flavour leptogenesis with tribimaximal mixings and beyond
Devi, H Zeen; Singh, N Nimai
2009-01-01T23:59:59.000Z
We compute and compare the baryon asymmetry of the universe in thermal leptogenesis scenario with and without flavour effects for different neutrino mass models namely degenerate, inverted hierarchical and normal hierarchical models, with tribimaximal mixings and beyond. Considering three possible diagonal forms of Dirac neutrino mass matrices $m_{LR}$, the right-handed Majorana mass matrices $M_{RR}$ are constructed from the light neutrino mass matrices $m_{LL}$ through the inverse seesaw formula. The normal hierarchical model is found to give the best predictions of the baryon asymmetry for both cases. This analysis serves as an additional information in the discrimination of the presently available neutrino mass models. Moreover, the flavour effects is found to give enhancement of the baryon asymmetry in thermal leptogenesis.
Scientific Opportunities with the Long-Baseline Neutrino Experiment
Adams, C.; et al.,
2013-07-28T23:59:59.000Z
In this document, we describe the wealth of science opportunities and capabilities of LBNE, the Long-Baseline Neutrino Experiment. LBNE has been developed to provide a unique and compelling program for the exploration of key questions at the forefront of particle physics. Chief among the discovery opportunities are observation of CP symmetry violation in neutrino mixing, resolution of the neutrino mass hierarchy, determination of maximal or near-maximal mixing in neutrinos, searches for nucleon decay signatures, and detailed studies of neutrino bursts from galactic supernovae. To fulfill these and other goals as a world-class facility, LBNE is conceived around four central components: (1) a new, intense wide-band neutrino source at Fermilab, (2) a fine-grained `near' neutrino detector just downstream of the source, (3) the Sanford Underground Research Facility (SURF) in Lead, South Dakota at an optimal distance (~1300 km) from the neutrino source, and (4) a massive liquid argon time-projection chamber (LArTPC) deployed there as a 'far' detector. The facilities envisioned are expected to enable many other science opportunities due to the high event rates and excellent detector resolution from beam neutrinos in the near detector and atmospheric neutrinos in the far detector. This is a mature, well developed, world class experiment whose relevance, importance, and probability of unearthing critical and exciting physics has increased with time.
New. nu. constraints on Majorana mass matrices
Dugan, M.J.; Manohar, A.; Nelson, A.E.
1985-07-08T23:59:59.000Z
We discuss constraints on the three by three Majorana neutrino mass matrix consistent with neutrinoless double ..beta.. decay experiments, neutrino oscillation experiments, and the existence of a 17-keV neutrino. We find that ..nu../sub ..mu../ and ..nu../sub tau/ must be nearly degenerate, or ..nu../sub ..mu../ must be heavier than 250 keV. A new parametrization of the mixing in the neutrino sector is proposed. We give a simple example of a mass matrix which satisfies all constraints.
Mertens, S; Fraenkle, F M; Furse, D; Glueck, F; Goerhardt, S; Hoetzel, M; Kaefer, W; Leiber, B; Thuemmler, T; Wandkowsky, N; Wolf, J
2012-01-01T23:59:59.000Z
The KATRIN experiment is designed to measure the absolute neutrino mass scale with a sensitivity of 200 meV at 90% C.L. by high resolution tritium beta-spectroscopy. A low background level of 10 mHz at the beta-decay endpoint is required in order to achieve the design sensitivity. In this paper we discuss a novel background source arising from magnetically trapped keV electrons in electrostatic retarding spectrometers. The main sources of these electrons are alpha-decays of the radon isotopes (219,220)Rn as well as beta-decays of tritium in the volume of the spectrometers. We characterize the expected background signal by extensive MC simulations and investigate the impact on the KATRIN neutrino mass sensitivity. From these results we refine design parameters for the spectrometer vacuum system and propose active background reduction methods to meet the stringent design limits for the overall background rate.
2010-01-01T23:59:59.000Z
accelerator experiments. Some neutrino oscillation experiments compare the flux in two or more detectors power reactors. 7 BOEHM 01 search for neutrino oscillations at 0.75 and 0.89 km distance from the Palo Verde reactors. 8 APOLLONIO 99, APOLLONIO 98 search for neutrino oscillations at 1.1 km fixed dis- tance
Universal Mass Texture, CP violation and Quark-Lepton Complementarity
Canales, F Gonzalez; Barranco, J
2010-01-01T23:59:59.000Z
Recent measurements of the neutrino and quark mixing angles satisfy the empirical relations called quark-lepton complementarity. These empirical relations suggests the existence of a correlation between the mixing matrices of leptons and quarks. In this work, we examine the possibility that this correlation between the mixing angles of quarks and leptons originates in the similar hierarchy of quarks and charged lepton masses and the seesaw mechanism type I, that gives mass to the Majorana neutrinos. We asssume that the similar mass hierarchies of charged lepton and quark masses allows us to represent all the mass matrices of Dirac fermions in terms of a two zeroes Fritzsch texture.
Universal mass matrix for quarks and leptons and CP violation
Barranco, J.; Gonzalez Canales, F.; Mondragon, A. [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Am Muehlenberg 1, D-14476 Golm (Germany); Instituto de Fisica, Universidad Nacional Autonoma de Mexico, 04510, Mexico D.F. (Mexico)
2010-10-01T23:59:59.000Z
The measurements of the neutrino and quark mixing angles satisfy the empirical relations called quark-lepton complementarity. These empirical relations suggest the existence of a correlation between the mixing matrices of leptons and quarks. In this work, we examine the possibility that this correlation between the mixing angles of quarks and leptons originates in the similar hierarchy of quarks and charged lepton masses and the seesaw mechanism type I, that gives mass to the Majorana neutrinos. We assume that the similar mass hierarchies of charged lepton and quark masses allows us to represent all the mass matrices of Dirac fermions in terms of a universal form with four texture zeroes.
CP-odd Weak Basis Invariants for Neutrino Mass Matrices with a Texture Zero and a Vanishing Minor
S. Dev; Shivani Gupta; Radha Raman Gautam
2010-10-19T23:59:59.000Z
We construct the $CP$-odd weak basis invariants in the flavor basis for all the phenomenologically viable neutrino mass matrices with a texture zero and a vanishing minor and, also, find the necessary and sufficient conditions for $CP$ invariance . We examine the interrelationships between different $CP$-odd weak basis invariants for these texture structures and investigate their implications for Dirac- and Majorana-type $CP$ violation.
CP-odd Weak Basis Invariants for Neutrino Mass Matrices with a Texture Zero and a Vanishing Minor
Dev, S; Gautam, Radha Raman
2010-01-01T23:59:59.000Z
We construct the $CP$-odd weak basis invariants in the flavor basis for all the phenomenologically viable neutrino mass matrices with a texture zero and a vanishing minor and, also, find the necessary and sufficient conditions for $CP$ invariance . We examine the interrelationships between different $CP$-odd weak basis invariants for these texture structures and investigate their implications for Dirac- and Majorana-type $CP$ violation.
F-theory and Neutrinos: Kaluza-Klein Dilution of Flavor Hierarchy
Seo, Jihye [Jefferson Physical Laboratory, Harvard University, Cambridge, MA 02138 (United States)
2010-02-10T23:59:59.000Z
We present a Majorana neutrino scenario in a F-theory SU(5) GUT model, which is recently proposed in [1]. The mass scale of the neutrinos arises from integrating out heavy Kaluza-Klein modes on the right-handed neutrinos. The participation of non-holomorphic Kaluza-Klein mode wave functions dilutes the mass hierarchy in comparison to the quark and charged lepton sectors, in agreement with experimentally measured mass splittings. The neutrinos are predicted to exhibit a 'normal' mass hierarchy, with masses (m{sub 3}, m{sub 2}, m{sub 1})approx.05x(1,alpha{sub GUT}{sup 1/2},alpha{sub GUT}) eV. The neutrino mixing matrix exhibits a mild hierarchical structure with theta{sub 13}approxalpha{sub GUT}{sup 1/2}approx0.2. We also predict mass measurements in single and double beta decay experiments.
Unitarity constraints on trimaximal mixing
Kumar, Sanjeev [Department of Physics and Astrophysics, University of Delhi, Delhi -110005 (India)
2010-07-01T23:59:59.000Z
When the neutrino mass eigenstate {nu}{sub 2} is trimaximally mixed, the mixing matrix is called trimaximal. The middle column of the trimaximal mixing matrix is identical to tribimaximal mixing and the other two columns are subject to unitarity constraints. This corresponds to a mixing matrix with four independent parameters in the most general case. Apart from the two Majorana phases, the mixing matrix has only one free parameter in the CP conserving limit. Trimaximality results in interesting interplay between mixing angles and CP violation. A notion of maximal CP violation naturally emerges here: CP violation is maximal for maximal 2-3 mixing. Similarly, there is a natural constraint on the deviation from maximal 2-3 mixing which takes its maximal value in the CP conserving limit.
Search for Matter-Dependent Atmospheric Neutrino Oscillations in Super-Kamiokande
The Super-Kamiokande Collaboration; K. Abe
2008-01-05T23:59:59.000Z
We consider muon neutrino to tau neutrino oscillations in the context of the Mass Varying Neutrino (MaVaN) model, where the neutrino mass can vary depending on the electron density along the flight path of the neutrino. Our analysis assumes a mechanism with dependence only upon the electron density, hence ordinary matter density, of the medium through which the neutrino travels. Fully-contained, partially-contained and upward-going muon atmospheric neutrino data from the Super--Kamiokande detector, taken from the entire SK--I period of 1489 live days, are compared to MaVaN model predictions. We find that, for the case of 2-flavor oscillations, and for the specific models tested, oscillation independent of electron density is favored over density dependence. Assuming maximal mixing, the best-fit case and the density-independent case do not differ significantly.
Are solar neutrino oscillations robust?
O. G. Miranda; M. A. Tortola; J. W. F. Valle
2006-09-07T23:59:59.000Z
The robustness of the large mixing angle (LMA) oscillation (OSC) interpretation of the solar neutrino data is considered in a more general framework where non-standard neutrino interactions (NSI) are present. Such interactions may be regarded as a generic feature of models of neutrino mass. The 766.3 ton-yr data sample of the KamLAND collaboration are included in the analysis, paying attention to the background from the reaction ^13C(\\alpha,n) ^16O. Similarly, the latest solar neutrino fluxes from the SNO collaboration are included. In addition to the solution which holds in the absence of NSI (LMA-I) there is a 'dark-side' solution (LMA-D) with sin^2 theta_Sol = 0.70, essentially degenerate with the former, and another light-side solution (LMA-0) allowed only at 97% CL. More precise KamLAND reactor measurements will not resolve the ambiguity in the determination of the solar neutrino mixing angle theta_Sol, as they are expected to constrain mainly Delta m^2. We comment on the complementary role of atmospheric, laboratory (e.g. CHARM) and future solar neutrino experiments in lifting the degeneracy between the LMA-I and LMA-D solutions. In particular, we show how the LMA-D solution induced by the simplest NSI between neutrinos and down-type-quarks-only is in conflict with the combination of current atmospheric data and data of the CHARM experiment. We also mention that establishing the issue of robustness of the oscillation picture in the most general case will require further experiments, such as those involving low energy solar neutrinos.
Mass independent textures and symmetry
Lam, C. S. [Department of Physics, McGill University, Montreal, QC, Canada H3A 2T8 and Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)
2006-12-01T23:59:59.000Z
A mass-independent texture is a set of linear relations of the fermion mass-matrix elements which imposes no constraint on the fermionic masses nor the Majorana phases. Magic and 2-3 symmetries are examples. We discuss the general construction and the properties of these textures, as well as their relation to the quark and neutrino mixing matrices. Such a texture may be regarded as a symmetry, whose unitary generators of the symmetry group can be explicitly constructed. In particular, the symmetries connected with the tribimaximal neutrino mixing matrix are discussed, together with the physical consequence of breaking one symmetry but preserving another.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
operators in the Lagrangian (Majorana mass terms), or both. The ongoing neutrinoless double-beta decay searches may be able to shine light on the matter. But the neutrino sector...
Majorana phases, CP violation, sterile neutrinos and neutrinoless double-beta decay
Babi?, Andrej [Department of Nuclear Physics and Biophysics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina, 842 48 Bratislava (Slovakia); Šimkovic, Fedor [Bogoliubov Laboratory of Theoretical Physics, JINR, Joliot-Curie 6, 141980 Dubna, Moscow region, Russia and Institute of Experimental and Applied Physics, Czech Technical University, CZ-128 00 Prague (Czech Republic)
2013-12-30T23:59:59.000Z
CP violation plays a crucial role in the generation of the baryon asymmetry in the Universe. Within this context we investigate the possibility of CP violation in the lepton sector caused by Majorana neutrino mixing. Focus is put on the model including 1 sterile neutrino. Both cases of normal and inverted neutrino mass spectrum are considered. We address the question whether the Majorana phases can be measured in the neutrinoless double-beta decay experiments with sensitivity to the effective Majorana neutrino mass of the order of 10{sup ?2} eV.
:,; Abe, K; Haga, Y; Hayato, Y; Iyogi, K; Kameda, J; Kishimoto, Y; Miura, M; Moriyama, S; Nakahata, M; Nakano, Y; Nakayama, S; Sekiya, H; Shiozawa, M; Suzuki, Y; Takeda, A; Tomura, T; Wendell, R A; Irvine, T; Kajita, 2 T; Kametani, I; Kaneyuki, 2 K; Lee, K P; Nishimura, Y; Okumura, 2 K; McLachlan, T; Labarga, 2 L; Kearns, E; Raaf, J L; Stone, 4 J L; Sulak, L R; Berkman, 4 S; Tanaka, 5 H A; Tobayama, 5 S; Goldhaber, M; Carminati, G; Kropp, W R; Mine, S; Renshaw, A; Smy, M B; Sobel, H W; Ganezer, K S; Hill, J; Hong, N; Kim, J Y; Lim, I T; Akiri, T; Himmel, A; Scholberg, K; Walter, C W; Wongjirad, T; Ishizuka, T; Tasaka, S; Jang, J S; Learned, J G; Matsuno, S; Smith, S N; Hasegawa, T; Ishida, T; Ishii, T; Kobayashi, T; Nakadaira, T; Nakamura, K; Oyama, Y; Sakashita, K; Sekiguchi, T; Tsukamoto, T; Suzuki, A T; Takeuchi, Y; Bronner, C; Hirota, S; Huang, K; Ieki, K; Ikeda, M; Kikawa, T; Minamino, A; Nakaya, T; Suzuki, K; Takahashi, S; Fukuda, Y; Itow, Y; Mitsuka, G; Mijakowski, P; Hignight, J; Imber, J; Jung, C K; Yanagisawa, C; Ishino, H; Kibayashi, A; Koshio, Y; Mori, T; Sakuda, M; Yano, T; Kuno, Y; Tacik, R; Kim, S B; Okazawa, H; Choi, Y; Nishijima, K; Koshiba, M; Totsuka, Y; Yokoyama, M; Martin, J F; de Perio, P; Konaka, A; Wilking, M J; Chen, S; Zhang, Y; Wilkes, R J
2015-01-01T23:59:59.000Z
Super-Kamiokande (SK) can search for weakly interacting massive particles (WIMPs) by detecting neutrinos produced from WIMP annihilations occurring inside the Sun. In this analysis, we include neutrino events with interaction vertices in the detector in addition to upward-going muons produced in the surrounding rock. Compared to the previous result, which used the upward-going muons only, the signal acceptances for light (few-GeV/$c^2$ $\\sim$ 200-GeV/$c^2$) WIMPs are significantly increased. We fit 3903 days of SK data to search for the contribution of neutrinos from WIMP annihilation in the Sun. We found no significant excess over expected atmospheric-neutrino background and the result is interpreted in terms of upper limits on WIMP-nucleon elastic scattering cross sections under different assumptions about the annihilation channel. We set the current best limits on the spin-dependent (SD) WIMP-proton cross section for WIMP masses below 200 GeV/$c^2$ (at 10 GeV/$c^2$, 1.49$\\times 10^{-39}$ cm$^2$ for $\\chi\\c...
Common Origin for Neutrino Anarchy and Charged Hierarchies
Agashe, Kaustubh [Center for Fundamental Physics, University of Maryland, College Park, Maryland 20742 (United States); Okui, Takemichi [Center for Fundamental Physics, University of Maryland, College Park, Maryland 20742 (United States); Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Sundrum, Raman [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Center for Fundamental Physics, University of Maryland, College Park, Maryland 20742 (United States)
2009-03-13T23:59:59.000Z
The generation of exponential flavor hierarchies from extra-dimensional wave function overlaps is reexamined. We find, surprisingly, that the coexistence of anarchic fermion mass matrices with such hierarchies is intrinsic and natural to this setting. The salient features of charged fermion and neutrino masses and mixings can thereby be captured within a single framework. Both Dirac and Majorana neutrinos can be realized. Implications for a variety of weak-scale scenarios, including warped compactification and supersymmetry, are discussed. When the new weak-scale physics is sensitive to the origin of flavor structure, Dirac neutrinos are preferred.
William G. Stanley; Gary C. Vezzoli
2001-02-07T23:59:59.000Z
Herein, we present a particle-based mechanism and mathematical formulation of gravity, focusing on the neutrino as the gravity-inducing particle. The mechanism is based on the primacy of momentum conservation and postulates an omni-directional distribution throughout the universe of fast small particles of finite mass that have a low probability of colliding with nucleons. The measured acceleration between two neighboring mass bodies results from an alteration of this distribution caused by nucleons of each body interacting with some of those particles. Based on findings establishing that the neutrino has mass, we evaluate the various neutrinos as external particle candidates. We show that for mass quantities up to several times that of the sun the form of the time rate of momentum transfer to each body is proportional to the product of the two body masses because of the probability nature of any collision process, and inversely proportional to the square of the distance between them because of the mathematical properties of an altered particle flux. A derived expression involving the neutrino momentum flux, the neutrino-nucleon collision cross section, and the nucleon mass replaces the constant G from the classical gravitational model. The neutrino momentum flux that is required to account for gravity is so large as to cause us herein to re-evaluate conventional notions in kinematics and the cause of inertial properties and to examine neutrino-nucleon collisions as a possible source of electromagnetic standing waves essential to establish electron shell states. This reasoning indicates that in a much more massive body that is accreting mass, a coulombic collapse to a black hole will ensue when external neutrinos lose the ability to penetrate in sufficient numbers to the central region.
An, Fengpeng; An, Qi; Antonelli, Vito; Baussan, Eric; Beacom, John; Bezrukov, Leonid; Blyth, Simon; Brugnera, Riccardo; Avanzini, Margherita Buizza; Busto, Jose; Cabrera, Anatael; Cai, Hao; Cai, Xiao; Cammi, Antonio; Cao, Guofu; Cao, Jun; Chang, Yun; Chen, Shaomin; Chen, Shenjian; Chen, Yixue; Chiesa, Davide; Clemenza, Massimiliano; Clerbaux, Barbara; Conrad, Janet; D'Angelo, Davide; De Kerret, Herve; Deng, Zhi; Deng, Ziyan; Ding, Yayun; Djurcic, Zelimir; Dornic, Damien; Dracos, Marcos; Drapier, Olivier; Dusini, Stefano; Dye, Stephen; Enqvist, Timo; Fan, Donghua; Fang, Jian; Favart, Laurent; Ford, Richard; Goger-Neff, Marianne; Gan, Haonan; Garfagnini, Alberto; Giammarchi, Marco; Gonchar, Maxim; Gong, Guanghua; Gong, Hui; Gonin, Michel; Grassi, Marco; Grewing, Christian; Guan, Mengyun; Guarino, Vic; Guo, Gang; Guo, Wanlei; Guo, Xin-Heng; Hagner, Caren; Han, Ran; He, Miao; Heng, Yuekun; Hsiung, Yee; Hu, Jun; Hu, Shouyang; Hu, Tao; Huang, Hanxiong; Huang, Xingtao; Huo, Lei; Ioannisian, Ara; Jeitler, Manfred; Ji, Xiangdong; Jiang, Xiaoshan; Jollet, Cecile; Kang, Li; Karagounis, Michael; Kazarian, Narine; Krumshteyn, Zinovy; Kruth, Andre; Kuusiniemi, Pasi; Lachenmaier, Tobias; Leitner, Rupert; Li, Chao; Li, Jiaxing; Li, Weidong; Li, Weiguo; Li, Xiaomei; Li, Xiaonan; Li, Yi; Li, Yufeng; Li, Zhi-Bing; Liang, Hao; Lin, Guey-Lin; Lin, Tao; Lin, Yen-Hsun; Ling, Jiajie; Lippi, Ivano; Liu, Dawei; Liu, Hongbang; Liu, Hu; Liu, Jianglai; Liu, Jianli; Liu, Jinchang; Liu, Qian; Liu, Shubin; Liu, Shulin; Lombardi, Paolo; Long, Yongbing; Lu, Haoqi; Lu, Jiashu; Lu, Jingbin; Lu, Junguang; Lubsandorzhiev, Bayarto; Ludhova, Livia; Luo, Shu; Lyashuk, Vladimir; Mollenberg, Randolph; Ma, Xubo; Mantovani, Fabio; Mao, Yajun; Mari, Stefano M; McDonough, William F; Meng, Guang; Meregaglia, Anselmo; Meroni, Emanuela; Mezzetto, Mauro; Miramonti, Lino; Mueller, Thomas; Naumov, Dmitry; Oberauer, Lothar; Ochoa-Ricoux, Juan Pedro; Olshevskiy, Alexander; Ortica, Fausto; Paoloni, Alessandro; Peng, Haiping; Peng, Jen-Chieh; Previtali, Ezio; Qi, Ming; Qian, Sen; Qian, Xin; Qian, Yongzhong; Qin, Zhonghua; Raffelt, Georg; Ranucci, Gioacchino; Ricci, Barbara; Robens, Markus; Romani, Aldo; Ruan, Xiangdong; Ruan, Xichao; Salamanna, Giuseppe; Shaevitz, Mike; Sinev, Valery; Sirignano, Chiara; Sisti, Monica; Smirnov, Oleg; Soiron, Michael; Stahl, Achim; Stanco, Luca; Steinmann, Jochen; Sun, Xilei; Sun, Yongjie; Taichenachev, Dmitriy; Tang, Jian; Tkachev, Igor; Trzaska, Wladyslaw; van Waasen, Stefan; Volpe, Cristina; Vorobel, Vit; Votano, Lucia; Wang, Chung-Hsiang; Wang, Guoli; Wang, Hao; Wang, Meng; Wang, Ruiguang; Wang, Siguang; Wang, Wei; Wang, Yi; Wang, Yifang; Wang, Zhe; Wang, Zheng; Wang, Zhigang; Wang, Zhimin; Wei, Wei; Wen, Liangjian; Wiebusch, Christopher; Wonsak, Bjorn; Wu, Qun; Wulz, Claudia-Elisabeth; Wurm, Michael; Xi, Yufei; Xia, Dongmei; Xie, Yuguang; Xing, Zhi-zhong; Xu, Jilei; Yan, Baojun; Yang, Changgen; Yang, Chaowen; Yang, Guang; Yang, Lei; Yang, Yifan; Yao, Yu; Yegin, Ugur; Yermia, Frederic; You, Zhengyun; Yu, Boxiang; Yu, Chunxu; Yu, Zeyuan; Zavatarelli, Sandra; Zhan, Liang; Zhang, Chao; Zhang, Hong-Hao; Zhang, Jiawen; Zhang, Jingbo; Zhang, Qingmin; Zhang, Yu-Mei; Zhang, Zhenyu; Zhao, Zhenghua; Zheng, Yangheng; Zhong, Weili; Zhou, Guorong; Zhou, Jing; Zhou, Li; Zhou, Rong; Zhou, Shun; Zhou, Wenxiong; Zhou, Xiang; Zhou, Yeling; Zhou, Yufeng; Zou, Jiaheng
2015-01-01T23:59:59.000Z
The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multi-purpose underground liquid scintillator detector, was proposed with the determination of the neutrino mass hierarchy as a primary physics goal. It is also capable of observing neutrinos from terrestrial and extra-terrestrial sources, including supernova burst neutrinos, diffuse supernova neutrino background, geoneutrinos, atmospheric neutrinos, solar neutrinos, as well as exotic searches such as nucleon decays, dark matter, sterile neutrinos, etc. We present the physics motivations and the anticipated performance of the JUNO detector for various proposed measurements. By detecting reactor antineutrinos from two power plants at 53-km distance, JUNO will determine the neutrino mass hierarchy at a 3-4 sigma significance with six years of running. The measurement of antineutrino spectrum will also lead to the precise determination of three out of the six oscillation parameters to an accuracy of better than 1\\%. Neutrino burst from a typical cor...
Minimal seesaw textures with two heavy neutrinos
Goswami, Srubabati [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India); Physical Research Laboratory, Navrangpura, Ahmedabad -380009 (India); Watanabe, Atsushi [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019 (India)
2009-02-01T23:59:59.000Z
We systematically analyze the Dirac and the Majorana mass matrices in seesaw models with two heavy right-handed neutrinos. We perform thorough classification of the vanishing matrix elements which are compatible with the results from the current neutrino oscillation experiments. We include the possibility of a nondiagonal Majorana mass matrix which leads to new solutions viable with data. In a basis where the Majorana mass matrix is diagonal, these solutions imply a Dirac matrix with specific relationships amongst its elements. We find that at the level of total four zeros together in m{sub D} and M{sub R} the mass matrices are almost consistent with the data but one mixing angle is predicted to be unsuitable. At the next level, i.e. with total three zeros, only seven patterns of mass matrices describe the experimental data well. The seven solutions have testable predictions for the future neutrino experiments. In particular, each solution has definite predictions about the observation of the 1-3 leptonic mixing angle and the effective mass measured in neutrinoless double beta decay. The solutions of the mass matrices contain novel texture forms and provide new insights into the lepton-generation structure. We also discuss possible connections between these textures and the tri-bimaximal mixing to search for symmetry principles behind the mass matrix structure.
Jaffe D. E.; Jaffe, D.E., et al. Daya Bay Collaboration
2014-10-01T23:59:59.000Z
A new measurement of the ?_{13} mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture result and an improvement on the precision of the ?_{13} measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GW_{th} reactors, the rate deficit observed at the far hall is interpreted as sin^{2}2?_{13}=0.083±0.018 in the three-flavor oscillation model. When combined with the gadolinium-capture result from Daya Bay, we obtain sin^{2}2?_{13}=0.089±0.008 as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.
Muon neutrino disappearance at MINOS
Armstrong, R.; /Indiana U.
2009-08-01T23:59:59.000Z
A strong case has been made by several experiments that neutrinos oscillate, although important questions remain as to the mechanisms and precise values of the parameters. In the standard picture, two parameters describe the nature of how the neutrinos oscillate: the mass-squared difference between states and the mixing angle. The purpose of this thesis is to use data from the MINOS experiment to precisely measure the parameters associated with oscillations first observed in studies of atmospheric neutrinos. MINOS utilizes two similar detectors to observe the oscillatory nature of neutrinos. The Near Detector, located 1 km from the source, observes the unoscillated energy spectrum while the Far Detector, located 735 km away, is positioned to see the oscillation signal. Using the data in the Near Detector, a prediction of the expected neutrino spectrum at the Far Detector assuming no oscillations is made. By comparing this prediction with the MINOS data, the atmospheric mixing parameters are measured to be {Delta}m{sub 32}{sup 2} = 2.45{sub +0.12}{sup -0.12} x 10{sub -3} eV{sup 2} and sin{sup 2}(2{theta}{sub 32}) = 1.00{sub -0.04}{sup +0.00} (> 0.90 at 90% confidence level).
Neutrino Nuclear Responses For Neutrino Studies In Nuclear Femto Laboratories
Ejiri, H. [Research Center for Nuclear Physics, Osaka University, Osaka 567-0047, Japan and Nuclear Science, Czech Technical University, Brehova, Prague (Czech Republic)
2011-12-16T23:59:59.000Z
Neutrinos are key particles for particle and astro-nuclear physics. Majorana neutrino masses and phases, solar and supernova neutrino productions and oscillations, and neutrino nuclear synthesis and fundamental weak interactions are well studied in nuclei as femto laboratories. Here neutrino nuclear responses are crucial for the neutrino studies. This reports briefly experimental studies of neutrino nuclear responses, charge exchange reactions on Ga to study nuclear responses for solar and {sup 51}Cr neutrinos, and {beta}{sup +} neutrino responses for {beta}{beta}-{nu} matrix elements and astro {nu} interactions by photon and muon probes.
Neutrinoless Double Beta Decay and Future Neutrino Oscillation Precision Experiments
S. Choubey; W. Rodejohann
2005-07-25T23:59:59.000Z
We discuss to what extent future precision measurements of neutrino mixing observables will influence the information we can draw from a measurement of (or an improved limit on) neutrinoless double beta decay. Whereas the Delta m^2 corresponding to solar and atmospheric neutrino oscillations are expected to be known with good precision, the parameter theta_{12} will govern large part of the uncertainty. We focus in particular on the possibility of distinguishing the neutrino mass hierarchies and on setting a limit on the neutrino mass. We give the largest allowed values of the neutrino masses which allow to distinguish the normal from the inverted hierarchy. All aspects are discussed as a function of the uncertainty stemming from the involved nuclear matrix elements. The implications of a vanishing, or extremely small, effective mass are also investigated. By giving a large list of possible neutrino mass matrices and their predictions for the observables, we finally explore how a measurement of (or an improved limit on) neutrinoless double beta decay can help to identify the neutrino mass matrix if more precise values of the relevant parameters are known.
Neutrinoless double beta decay and future neutrino oscillation precision experiments
Choubey, Sandhya [Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Rodejohann, Werner [Physik-Department, Technische Universitaet Muenchen, James-Franck-Strasse, D-85748 Garching (Germany)
2005-08-01T23:59:59.000Z
We discuss to what extent future precision measurements of neutrino mixing observables will influence the information we can draw from a measurement of (or an improved limit on) neutrinoless double beta decay. Whereas the {delta}m{sup 2} corresponding to solar and atmospheric neutrino oscillations are expected to be known with good precision, the parameter {theta}{sub 12} will govern a large part of the uncertainty. We focus, in particular, on the possibility of distinguishing the neutrino mass hierarchies and on setting a limit on the neutrino mass. We give the largest allowed values of the neutrino masses which allow to distinguish the normal from the inverted hierarchy. All aspects are discussed as a function of the uncertainty stemming from the involved nuclear matrix elements. The implications of a vanishing, or extremely small, effective mass are also investigated. By giving a large list of possible neutrino mass matrices and their predictions for the observables, we finally explore how a measurement of (or an improved limit on) neutrinoless double beta decay can help to identify the neutrino mass matrix if more precise values of the relevant parameters are known.
Oscillations of Mossbauer neutrinos
Evgeny Kh. Akhmedov; Joachim Kopp; Manfred Lindner
2008-05-02T23:59:59.000Z
We calculate the probability of recoilless emission and detection of neutrinos (Mossbauer effect with neutrinos) taking into account the boundedness of the parent and daughter nuclei in the neutrino source and detector as well as the leptonic mixing. We show that, in spite of their near monochromaticity, the recoillessly emitted and captured neutrinos oscillate. After a qualitative discussion of this issue, we corroborate and extend our results by computing the combined rate of $\\bar{\
A search for muon neutrino to electron neutrino oscillations at delta(m^2)>0.1 eV^2
Patterson, Ryan Benton; /Princeton U.
2007-11-01T23:59:59.000Z
The evidence is compelling that neutrinos undergo flavor change as they propagate. In recent years, experiments have observed this phenomenon of neutrino oscillations using disparate neutrino sources: the sun, fission reactors, accelerators, and secondary cosmic rays. The standard model of particle physics needs only simple extensions - neutrino masses and mixing - to accommodate all neutrino oscillation results to date, save one. The 3.8{sigma}-significant {bar {nu}}{sub e} excess reported by the LSND collaboration is consistent with {bar {nu}}{sub {mu}} {yields}{bar {nu}}{sub e} oscillations with a mass-squared splitting of {Delta}m{sup 2} {approx} 1 eV{sup 2}. This signal, which has not been independently verified, is inconsistent with other oscillation evidence unless more daring standard model extensions (e.g. sterile neutrinos) are considered.
Are the small neutrino oscillation parameters all related?
Pramanick, Soumita
2014-01-01T23:59:59.000Z
Neutrino oscillations reveal several small parameters, namely, \\theta_{13}, the solar mass splitting vis-a-vis the atmospheric one, and the deviation of \\theta_{23} from maximal mixing. Can these small quantities all be traced to a single source and, if so, how could that be tested? Here a see-saw model for neutrino masses is presented wherein a dominant term generates the atmospheric mass splitting with maximal mixing in this sector, keeping \\theta_{13} = 0 and zero solar splitting. A Type-I see-saw perturbative contribution results in non-zero values of \\theta_{13}, \\Delta m^2_{solar}, \\theta_{12}, as well as allows \\theta_{23} to deviate from \\pi/4 in consistency with the data while interrelating them all. CP-violation is a natural consequence and is large for inverted mass ordering. The model will be tested as precision on the neutrino parameters is sharpened.
G. J. Mathews; T. Kajino; W. Aoki; W. Fujiya; J. B. Pitts
2012-04-17T23:59:59.000Z
There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced {\
ATOC/CHEM 5151 Problem 5 Converting Volume Mixing Ratio to Mass Density
Toohey, Darin W.
, 2014 In 2012, the dry mixing ratio volume of sulfur hexafluoride (SF6) in the atmosphere was about 7.5 parts per trillion by volume ("pptv" or "ppt"). Convert this value into the mass density of SF6 in units of micrograms of SF6 per cubic meter of air ("g m-3" ). Source of information: MW(SF6)= 146 g mol-1 Methodology
Differentiating neutrino models on the basis of $\\theta_{13}$ and lepton flavor violation
Albright, Carl H.; /Northern Illinois U. /Fermilab
2008-03-01T23:59:59.000Z
The authors show how models of neutrino masses and mixings can be differentiated on the basis of their predictions for {theta}{sub 13} and lepton flavor violation in radiative charged lepton decays and {mu} - e conversion. They illustrate the lepton flavor violation results for five predictive SO(10) SUSY GUT models and point out the relative importance of their heavy right-handed neutrino mass spectra and {theta}{sub 13} predictions.
Solar Neutrino Precision Measurements using all 1496 Days of Super-Kamiokande-I Data
M. B. Smy
2002-08-05T23:59:59.000Z
The results of the entire Super-Kamiokande-I solar neutrino data are presented. The measured interaction rate is 47+-2% of the rate expected by the standard solar model and 133+-5% of the rate implied by the SNO charged-current interaction rate. There is no evidence for spectral distortion or a time dependent neutrino flux. Together with the rates of other experiments, the Super-Kamiokande results imply active solar neutrino oscillations and restrict neutrino mixing and mass square difference to lie within the LMA solution area.
Are the B decay anomalies related to neutrino oscillations?
Boucenna, Sofiane M; Vicente, Avelino
2015-01-01T23:59:59.000Z
Neutrino oscillations are solidly established, with a hint of CP violation just emerging. Similarly, there are hints of lepton universality violation in $b \\to s$ transitions at the level of $2.6 \\sigma$. By assuming that the unitary transformation between weak and mass charged leptons equals the leptonic mixing matrix measured in neutrino oscillation experiments, we predict several lepton flavor violating (LFV) B meson decays. We are led to the tantalizing possibility that some LFV branching ratios for B decays correlate with the leptonic CP phase $\\delta$ characterizing neutrino oscillations. Moreover, we also consider implications for $\\ell_i \\to \\ell_j \\ell_k \\ell_k$ decays.
Naturalness-guided Gluino Mass Bound from the Minimal Mixed Mediation of SUSY Breaking
Doyoun Kim; Bumseok Kyae
2015-07-28T23:59:59.000Z
In order to significantly reduce the fine-tuning associated with the electroweak symmetry breaking in the minimal supersymmetric standard model (MSSM), we consider not only the minimal gravity mediation effects but also the minimal gauge mediation ones for a common supersymmetry breaking source at a hidden sector. In this "Minimal Mixed Mediation model," the minimal forms for the Kahler potential and the gauge kinetic function are employed at tree level. The MSSM gaugino masses are radiatively generated through the gauge mediation. Since a "focus point" of the soft Higgs mass parameter, m_{h_u}^2 appears around 3-4 TeV energy scale in this case, m_{h_u}^2 is quite insensitive to stop masses. Instead, the naturalness of the small m_{h_u}^2 is more closely associated with the gluino mass rather than the stop mass unlike the conventional scenario. As a result, even a 3-4 TeV stop mass, which is known to explain the 125 GeV Higgs mass at three-loop level, can still be compatible with the naturalness of the electroweak scale. On the other hand, the requirements of various fine-tuning measures much smaller than 100 and |\\mu| potential range of LHC RunII.
Naturalness-guided Gluino Mass Bound from the Minimal Mixed Mediation of SUSY Breaking
Kim, Doyoun
2015-01-01T23:59:59.000Z
In order to significantly reduce the fine-tuning associated with the electroweak symmetry breaking in the minimal supersymmetric standard model (MSSM), we consider not only the minimal gravity mediation effects but also the minimal gauge mediation ones for a common supersymmetry breaking source at a hidden sector. In this "Minimal Mixed Mediation model," the minimal forms for the Kahler potential and the gauge kinetic function are employed at tree level. The MSSM gaugino masses are radiatively generated through the gauge mediation. Since a "focus point" of the soft Higgs mass parameter, m_{h_u}^2 appears around 3-4 TeV energy scale in this case, m_{h_u}^2 is quite insensitive to stop masses. Instead, the naturalness of the small m_{h_u}^2 is more closely associated with the gluino mass rather than the stop mass unlike the conventional scenario. As a result, even a 3-4 TeV stop mass, which is known to explain the 125 GeV Higgs mass at three-loop level, can still be compatible with the naturalness of the electr...
James Barry; Rabindra N. Mohapatra; Werner Rodejohann
2011-06-27T23:59:59.000Z
The standard assumption is that all three neutrino mass states are either Dirac or Majorana. However, it was recently suggested by Allaverdi, Dutta and one of the authors (R.N.M.) that mixed, or bimodal, flavor neutrino scenarios are conceivable and are consistent with all known observations (these were called "schizophrenic" in the ADM paper). In that case each individual mass eigenstate can be either Dirac or Majorana, so that the flavor eigenstates are "large" admixtures of both. An example of this "bimodal" situation is to consider one mass state as a Dirac particle (with a sterile partner), while the other two are of Majorana type. Since only Majorana particles contribute to neutrinoless double beta decay, the usual dependence of this observable on the neutrino mass is modified within this scenario. We study this in detail and, in particular, generalize the idea for all possible bimodal combinations. Inevitably, radiative corrections will induce a pseudo-Dirac nature to the Dirac states at the one-loop level, and the effects of the pseudo-Dirac mass splitting will show up in the flavor ratios of neutrinos from distant cosmological sources. Comparison of the effective mass in neutrinoless double beta decay as well as flavor ratios at neutrino telescopes, for different pseudo-Dirac cases and with their usual phenomenology, can distinguish the different bimodal possibilities.
Z .Physics Letters B 480 2000 1218 Detection of very small neutrino masses in double-beta decay
Gratta, Giorgio
that new techniques in dark matter, solar neutrino, and neutrinoless double beta decay have the resources
Amand Faessler; Fedor Simkovic
2015-04-07T23:59:59.000Z
The atomic pair 163 Holmium and 163 Dysprosium seems due to the small Q value of about 2.3 to 2.8 keV the best case to determine the neutrino mass by electron capture. The bolometer spectrum measures the full deexcitation energy of Dysprosium by X rays, by Auger electrons and by the recoil of Holmium. The spectrum has an upper energy limit given by the Q value minus the neutrino mass. Till now this spectrum has been calculated allowing in Dysprosium excitations with 3s1/2, 3p1/2, 4s1/2, 4p1/2, 5s1/2, 5p1/2 one-holes only. Robertson calculated recently also the spectrum with two electron hole excitations in Dy. He took the probability for the excitation for the second electron hole from work of Carlson and Nestor for Z=54 Xenon. He claims, that the bolometer spectrum with two holes is "not well enough understood to permit a sensitive determination of the neutrino mass in this way." The purpose of the present work is to determine the theoretical bolometer spectrum with two hole excitations more reliably directly in holmium and dysprosium. In addition it will be shown, that the two-hole excitations do not complicate more the determination of the neutrino mass compared to the situation with one-hole states only. At the Q value the highest one-hole resonance is dominant. Under the assumption of a Lorentzian line shape one has to fit after inclusion of the experimental spectral function of the detector four quantities to the data: (1) The neutrino mass, (2) the energy distance of the dominant resonance to the Q value, (3) the line witdth and (4) the strength of the resonance. Compared to Robertson this work includes major improvements and it shows, that a determination of the neutrino mass is difficult but not impossible.
Niki Saoulidou
2010-01-08T23:59:59.000Z
Neutrino oscillations provide the first evidence for physics beyond the Standard Model. I will briefly overview the neutrino "hi-story", describing key discoveries over the past decades that shaped our understanding of neutrinos and their behavior. Fermilab was, is and hopefully will be at the forefront of the accelerator neutrino experiments. NuMI, the most powerful accelerator neutrino beam in the world has ushered us into the era of precise measurements. Its further upgrades may give a chance to tackle the remaining mysteries of the neutrino mass hierarchy and possible CP violation.
Physics Potential of the ICAL detector at the India-based Neutrino Observatory (INO)
The ICAL Collaboration; Shakeel Ahmed; M. Sajjad Athar; Rashid Hasan; Mohammad Salim; S. K. Singh; S. S. R. Inbanathan; Venktesh Singh; V. S. Subrahmanyam; Shiba Prasad Behera; Vinay B. Chandratre; Nitali Dash; Vivek M. Datar; V. K. S. Kashyap; Ajit K. Mohanty; Lalit M. Pant; Animesh Chatterjee; Sandhya Choubey; Raj Gandhi; Anushree Ghosh; Deepak Tiwari; Ali Ajmi; S. Uma Sankar; Prafulla Behera; Aleena Chacko; Sadiq Jafer; James Libby; K. Raveendrababu; K. R. Rebin; D. Indumathi; K. Meghna; S. M. Lakshmi; M. V. N. Murthy; Sumanta Pal; G. Rajasekaran; Nita Sinha; Sanjib Kumar Agarwalla; Amina Khatun; Poonam Mehta; Vipin Bhatnagar; R. Kanishka; A. Kumar; J. S. Shahi; J. B. Singh; Monojit Ghosh; Pomita Ghoshal; Srubabati Goswami; Chandan Gupta; Sushant Raut; Sudeb Bhattacharya; Suvendu Bose; Ambar Ghosal; Abhik Jash; Kamalesh Kar; Debasish Majumdar; Nayana Majumdar; Supratik Mukhopadhyay; Satyajit Saha; B. S. Acharya; Sudeshna Banerjee; Kolahal Bhattacharya; Sudeshna Dasgupta; Moon Moon Devi; Amol Dighe; Gobinda Majumder; Naba K. Mondal; Asmita Redij; Deepak Samuel; B. Satyanarayana; Tarak Thakore; C. D. Ravikumar; A. M. Vinodkumar; Gautam Gangopadhyay; Amitava Raychaudhuri; Brajesh C. Choudhary; Ankit Gaur; Daljeet Kaur; Ashok Kumar; Sanjeev Kumar; Md. Naimuddin; Waseem Bari; Manzoor A. Malik; Jyotsna Singh; S. Krishnaveni; H. B. Ravikumar; C. Ranganathaiah; Swapna Mahapatra; Saikat Biswas; Subhasis Chattopadhyay; Rajesh Ganai; Tapasi Ghosh; Y. P. Viyogi
2015-05-27T23:59:59.000Z
The upcoming 50 kt magnetized iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) is designed to study the atmospheric neutrinos and antineutrinos separately over a wide range of energies and path lengths. The primary focus of this experiment is to explore the Earth matter effects by observing the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. This study will be crucial to address some of the outstanding issues in neutrino oscillation physics, including the fundamental issue of neutrino mass hierarchy. In this document, we present the physics potential of the detector as obtained from realistic detector simulations. We describe the simulation framework, the neutrino interactions in the detector, and the expected response of the detector to particles traversing it. The ICAL detector can determine the energy and direction of the muons to a high precision, and in addition, its sensitivity to multi-GeV hadrons increases its physics reach substantially. Its charge identification capability, and hence its ability to distinguish neutrinos from antineutrinos, makes it an efficient detector for determining the neutrino mass hierarchy. In this report, we outline the analyses carried out for the determination of neutrino mass hierarchy and precision measurements of atmospheric neutrino mixing parameters at ICAL, and give the expected physics reach of the detector with 10 years of runtime. We also explore the potential of ICAL for probing new physics scenarios like CPT violation and the presence of magnetic monopoles.
D-Dbar Mixing in the Standard Model and Beyond from Nf=2 Twisted Mass QCD
N. Carrasco; M. Ciuchini; P. Dimopoulos; R. Frezzotti; V. Gimenez; V. Lubicz; G. C. Rossi; F. Sanfilippo; L. Silvestrini; S. Simula; C. Tarantino
2014-06-13T23:59:59.000Z
We present the first unquenched lattice QCD results for the bag parameters controlling the short distance contribution to D meson oscillations in the Standard Model and beyond. We have used the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2 dynamical quarks, at four lattice spacings and light meson masses in the range 280-500 MeV. Renormalization is carried out non-perturbatively with the RI-MOM method. The bag-parameter results have been used to constrain New Physics effects in D-Dbar mixing, to put a lower bound to the generic New Physics scale and to constrain off-diagonal squark mass terms for TeV-scale Supersymmetry.
Status of Neutrino Oscillations
J. W. F. Valle
2001-04-04T23:59:59.000Z
Solar and atmospheric neutrino data require physics beyond the Standard Model of particle physics. The simplest, most generic, but not yet unique, interpretation of the data is in terms of neutrino oscillations. I summarize the results of the latest three-neutrino oscillation global fit of the data, in particular the bounds on the angle $\\theta_{13}$ probed in reactor experiments. Even though not implied by the data, bi-maximal neutrino mixing emerges as an attractive possibility either in hierarchical or quasi-degenerate neutrino scenarios.
Kajino, Toshitaka [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Department of Astronomy, Graduate School of Science, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan)
2011-05-06T23:59:59.000Z
Neutrinos play the critical roles in nucleosynthesis of light-to-heavy mass nuclei in core-collapse supernovae. We study the nucleosynthesis induced by neutrino interactions and find suitable average neutrino temperatures in order to explain the observed solar system abundances of several isotopes {sup 7}Li, {sup 11}B, {sup 138}La and {sup 180}Ta. These isotopes are predominantly synthesized by the supernova {nu}-process. We also study the neutrino oscillation effects on their abundances and propose a method to determine the unknown neutrino oscillation parameters, i.e. {theta}{sub 13} and mass hierarchy.
A Tale of Two Timescales: Mixing, Mass Generation, and Phase Transitions in the Early Universe
Dienes, Keith R; Thomas, Brooks
2015-01-01T23:59:59.000Z
Light scalar fields such as axions and string moduli can play an important role in early-universe cosmology. However, many factors can significantly impact their late-time cosmological abundances. For example, in cases where the potentials for these fields are generated dynamically --- such as during cosmological mass-generating phase transitions --- the duration of the time interval required for these potentials to fully develop can have significant repercussions. Likewise, in scenarios with multiple scalars, mixing amongst the fields can also give rise to an effective timescale that modifies the resulting late-time abundances. Previous studies have focused on the effects of either the first or the second timescale in isolation. In this paper, by contrast, we examine the new features that arise from the interplay between these two timescales when both mixing and time-dependent phase transitions are introduced together. First, we find that the effects of these timescales can conspire to alter not only the tot...
Massive neutrinos and cosmology
Julien Lesgourgues; Sergio Pastor
2006-05-29T23:59:59.000Z
The present experimental results on neutrino flavour oscillations provide evidence for non-zero neutrino masses, but give no hint on their absolute mass scale, which is the target of beta decay and neutrinoless double-beta decay experiments. Crucial complementary information on neutrino masses can be obtained from the analysis of data on cosmological observables, such as the anisotropies of the cosmic microwave background or the distribution of large-scale structure. In this review we describe in detail how free-streaming massive neutrinos affect the evolution of cosmological perturbations. We summarize the current bounds on the sum of neutrino masses that can be derived from various combinations of cosmological data, including the most recent analysis by the WMAP team. We also discuss how future cosmological experiments are expected to be sensitive to neutrino masses well into the sub-eV range.
Fengpeng An; Guangpeng An; Qi An; Vito Antonelli; Eric Baussan; John Beacom; Leonid Bezrukov; Simon Blyth; Riccardo Brugnera; Margherita Buizza Avanzini; Jose Busto; Anatael Cabrera; Hao Cai; Xiao Cai; Antonio Cammi; Guofu Cao; Jun Cao; Yun Chang; Shaomin Chen; Shenjian Chen; Yixue Chen; Davide Chiesa; Massimiliano Clemenza; Barbara Clerbaux; Janet Conrad; Davide D'Angelo; Herve De Kerret; Zhi Deng; Ziyan Deng; Yayun Ding; Zelimir Djurcic; Damien Dornic; Marcos Dracos; Olivier Drapier; Stefano Dusini; Stephen Dye; Timo Enqvist; Donghua Fan; Jian Fang; Laurent Favart; Richard Ford; Marianne Goger-Neff; Haonan Gan; Alberto Garfagnini; Marco Giammarchi; Maxim Gonchar; Guanghua Gong; Hui Gong; Michel Gonin; Marco Grassi; Christian Grewing; Mengyun Guan; Vic Guarino; Gang Guo; Wanlei Guo; Xin-Heng Guo; Caren Hagner; Ran Han; Miao He; Yuekun Heng; Yee Hsiung; Jun Hu; Shouyang Hu; Tao Hu; Hanxiong Huang; Xingtao Huang; Lei Huo; Ara Ioannisian; Manfred Jeitler; Xiangdong Ji; Xiaoshan Jiang; Cecile Jollet; Li Kang; Michael Karagounis; Narine Kazarian; Zinovy Krumshteyn; Andre Kruth; Pasi Kuusiniemi; Tobias Lachenmaier; Rupert Leitner; Chao Li; Jiaxing Li; Weidong Li; Weiguo Li; Xiaomei Li; Xiaonan Li; Yi Li; Yufeng Li; Zhi-Bing Li; Hao Liang; Guey-Lin Lin; Tao Lin; Yen-Hsun Lin; Jiajie Ling; Ivano Lippi; Dawei Liu; Hongbang Liu; Hu Liu; Jianglai Liu; Jianli Liu; Jinchang Liu; Qian Liu; Shubin Liu; Shulin Liu; Paolo Lombardi; Yongbing Long; Haoqi Lu; Jiashu Lu; Jingbin Lu; Junguang Lu; Bayarto Lubsandorzhiev; Livia Ludhova; Shu Luo; Vladimir Lyashuk; Randolph Mollenberg; Xubo Ma; Fabio Mantovani; Yajun Mao; Stefano M. Mari; William F. McDonough; Guang Meng; Anselmo Meregaglia; Emanuela Meroni; Mauro Mezzetto; Lino Miramonti; Thomas Mueller; Dmitry Naumov; Lothar Oberauer; Juan Pedro Ochoa-Ricoux; Alexander Olshevskiy; Fausto Ortica; Alessandro Paoloni; Haiping Peng; Jen-Chieh Peng; Ezio Previtali; Ming Qi; Sen Qian; Xin Qian; Yongzhong Qian; Zhonghua Qin; Georg Raffelt; Gioacchino Ranucci; Barbara Ricci; Markus Robens; Aldo Romani; Xiangdong Ruan; Xichao Ruan; Giuseppe Salamanna; Mike Shaevitz; Valery Sinev; Chiara Sirignano; Monica Sisti; Oleg Smirnov; Michael Soiron; Achim Stahl; Luca Stanco; Jochen Steinmann; Xilei Sun; Yongjie Sun; Dmitriy Taichenachev; Jian Tang; Igor Tkachev; Wladyslaw Trzaska; Stefan van Waasen; Cristina Volpe; Vit Vorobel; Lucia Votano; Chung-Hsiang Wang; Guoli Wang; Hao Wang; Meng Wang; Ruiguang Wang; Siguang Wang; Wei Wang; Yi Wang; Yi Wang; Yifang Wang; Zhe Wang; Zheng Wang; Zhigang Wang; Zhimin Wang; Wei Wei; Liangjian Wen; Christopher Wiebusch; Bjorn Wonsak; Qun Wu; Claudia-Elisabeth Wulz; Michael Wurm; Yufei Xi; Dongmei Xia; Yuguang Xie; Zhi-zhong Xing; Jilei Xu; Baojun Yan; Changgen Yang; Chaowen Yang; Guang Yang; Lei Yang; Yifan Yang; Yu Yao; Ugur Yegin; Frederic Yermia; Zhengyun You; Boxiang Yu; Chunxu Yu; Zeyuan Yu; Sandra Zavatarelli; Liang Zhan; Chao Zhang; Hong-Hao Zhang; Jiawen Zhang; Jingbo Zhang; Qingmin Zhang; Yu-Mei Zhang; Zhenyu Zhang; Zhenghua Zhao; Yangheng Zheng; Weili Zhong; Guorong Zhou; Jing Zhou; Li Zhou; Rong Zhou; Shun Zhou; Wenxiong Zhou; Xiang Zhou; Yeling Zhou; Yufeng Zhou; Jiaheng Zou
2015-07-20T23:59:59.000Z
The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multi-purpose underground liquid scintillator detector, was proposed with the determination of the neutrino mass hierarchy as a primary physics goal. It is also capable of observing neutrinos from terrestrial and extra-terrestrial sources, including supernova burst neutrinos, diffuse supernova neutrino background, geoneutrinos, atmospheric neutrinos, solar neutrinos, as well as exotic searches such as nucleon decays, dark matter, sterile neutrinos, etc. We present the physics motivations and the anticipated performance of the JUNO detector for various proposed measurements. By detecting reactor antineutrinos from two power plants at 53-km distance, JUNO will determine the neutrino mass hierarchy at a 3-4 sigma significance with six years of running. The measurement of antineutrino spectrum will also lead to the precise determination of three out of the six oscillation parameters to an accuracy of better than 1\\%. Neutrino burst from a typical core-collapse supernova at 10 kpc would lead to ~5000 inverse-beta-decay events and ~2000 all-flavor neutrino-proton elastic scattering events in JUNO. Detection of DSNB would provide valuable information on the cosmic star-formation rate and the average core-collapsed neutrino energy spectrum. Geo-neutrinos can be detected in JUNO with a rate of ~400 events per year, significantly improving the statistics of existing geoneutrino samples. The JUNO detector is sensitive to several exotic searches, e.g. proton decay via the $p\\to K^++\\bar\
Gnanadesikan, Anand
colleagues suggests that without this heat transport the globe would freeze over, [Winton, 2003Sensitivity of water mass transformation and heat transport to subgridscale mixing in coarse of subgridscale mixing on ocean heat transport in coarse- resolution ocean models of the type used in coupled
Majorana neutrino superfluidity and stability of neutrino dark energy
Bhatt, Jitesh R.; Sarkar, Utpal [Physical Research Laboratory, Ahmedabad 380009 (India)
2009-08-15T23:59:59.000Z
We demonstrate that Majorana neutrinos can form Cooper pairs due to long-range attractive forces and show BCS superfluidity in a class of mass varying neutrino dark energy models. We describe the condensates for Majorana neutrinos and estimate the value of the gap, critical temperature, and Pippard coherence length for a simple neutrino dark energy model. In the strong coupling regime bosonic degree of freedom can become important, and Bose-Einstein condensate may govern the dynamics for the mass varying neutrino models. Formation of the condensates can significantly alter the instability scenario in the mass varying neutrino models.
Radiatively broken symmetries of nonhierarchical neutrinos
Amol Dighe; Srubabati Goswami; Probir Roy
2007-09-17T23:59:59.000Z
Symmetry-based ideas, such as the quark-lepton complementarity (QLC) principle and the tri-bimaximal mixing (TBM) scheme, have been proposed to explain the observed mixing pattern of neutrinos. We argue that such symmetry relations need to be imposed at a high scale $\\Lambda \\sim 10^{12}$ GeV characterizing the large masses of right-handed neutrinos required to implement the seesaw mechanism. For nonhierarchical neutrinos, renormalisation group evolution down to a laboratory energy scale $\\lambda \\sim 10^3$ GeV tends to radiatively break these symmetries at a significant level and spoil the mixing pattern predicted by them. However, for Majorana neutrinos, suitable constraints on the extra phases $\\alpha_{2,3}$ enable the retention of those high scale mixing patterns at laboratory energies. We examine this issue within the Minimal Supersymmetric Standard Model (MSSM) and demonstrate the fact posited above for two versions of QLC and two versions of TBM. The appropriate constraints are worked out for all these four cases. Specifically, a preference for $\\alpha_2 \\approx \\pi$ (i.e. $m_1 \\approx -m_2$) emerges in each case. We also show how a future accurate measurement of $\\theta_{13}$ may enable some discrimination among these four cases in spite of renormalization group evolution.
Optimisation of future long baseline neutrino experiments
Olga Mena
2008-09-28T23:59:59.000Z
The aim of this talk is to review near and far future long baseline neutrino experiments as superbeams, beta-Beams and neutrino factories, comparing their sensitivities to the unknown parameters in the neutrino oscillation sector. We focus on the extraction of the neutrino mass hierarchy, exploring alternatives to the commonly used neutrino-antineutrino comparison. Special attention to a new concept of neutrino factory design, the low energy neutrino factory, is given.
Measurements of the masses, lifetimes and mixings of B hadrons at the Tevatron
Malde, S; /Oxford U.
2009-09-01T23:59:59.000Z
The Tevatron, with p{bar p} collisions at {radical}s = 1.96 TeV, can produce all flavors of B hadrons and allows for unprecedented studies in the B physics sector. The CDF and D0 collaborations have more than 5 fb{sup -1} of data recorded. I present here a selection of recent results on the masses, lifetimes and mixings of B hadrons using between 1.0 and 2.8 fb{sup -1} of data.
Testable two-loop radiative neutrino mass model based on an $LLQd^cQd^c$ effective operator
Paul W. Angel; Yi Cai; Nicholas L. Rodd; Michael A. Schmidt; Raymond R. Volkas
2014-10-03T23:59:59.000Z
A new two-loop radiative Majorana neutrino mass model is constructed from the gauge-invariant effective operator $L^i L^j Q^k d^c Q^l d^c \\epsilon_{ik} \\epsilon_{jl}$ that violates lepton number conservation by two units. The ultraviolet completion features two scalar leptoquark flavors and a color-octet Majorana fermion. We show that there exists a region of parameter space where the neutrino oscillation data can be fitted while simultaneously meeting flavor-violation and collider bounds. The model is testable through lepton flavor-violating processes such as ${\\mu} \\to e{\\gamma}$, $\\mu \\to eee$, and $\\mu N \\to eN$ conversion, as well as collider searches for the scalar leptoquarks and color-octet fermion. We computed and compiled a list of necessary Passarino-Veltman integrals up to boxes in the approximation of vanishing external momenta and made them available as a Mathematica package, denoted as ANT.
Gauge Theory Model of the Neutrino and New Physics Beyond the Standard Model
Yue-Liang Wu
2012-03-05T23:59:59.000Z
Majorana features of neutrinos and SO(3) gauge symmetry of three families enable us to construct a gauge model of neutrino for understanding naturally the observed smallness of neutrino masses and the nearly tri-bimaximal neutrino mixing when combining together with the mechanism of approximate global U(1) family symmetry. The vacuum structure of SO(3) symmetry breaking is found to play an important role. The mixing angle $\\theta_{13}$ and CP-violating phases governed by the vacuum of spontaneous symmetry breaking are in general non-zero and testable experimentally at the allowed sensitivity. The model predicts the existence of vector-like SO(3) triplet charged leptons and vector-like SO(3) triplet Majorana neutrinos as well as SO(3) tri-triplet Higgs bosons, some of them can be light and explored at the colliders LHC and ILC.
Light pseudoscalar meson masses and decay constants from mixed action lattice QCD
Christopher Aubin; Jack Laiho; Ruth S. Van de Water
2008-10-23T23:59:59.000Z
We calculate the light pseudoscalar decay constants, f_pi and f_K, and their ratio using domain wall valence quarks and 2+1 flavors of dynamical staggered quarks. Use of the MILC gauge configurations allows us to simulate at several sea quark masses and spatial volumes, and with two lattice spacings. We study how well our numerical lattice data for light decay constants and meson masses is described by next-to-leading order SU(3) mixed action chiral perturbation theory and explain our strategy for the chiral and continuum extrapolation. Combining our result for f_K/f_pi with experimental measurements of pion and kaon leptonic decays allows a model-independent determination of |V_us|/|V_ud|; we find a preliminary value of |V_us|/|V_ud| = 0.2315(45)(7).
Solar Neutrino Matter Effects Redux
A. B. Balantekin; A. Malkus
2011-12-19T23:59:59.000Z
Following recent low-threshold analysis of the Sudbury Neutrino Observatory and asymmetry measurements of the BOREXINO Collaboration of the solar neutrino flux, we revisit the analysis of the matter effects in the Sun. We show that solar neutrino data constrains the mixing angle $\\theta_{13}$ poorly and that subdominant Standard Model effects can mimic the effects of the physics beyond the Standard Model.
Xin-Heng Guo; Ming-Yang Huang; Bing-Lin Young
2009-04-14T23:59:59.000Z
In this paper, we first calculate the realistic Earth matter effects in the detection of type II supernova neutrinos at the Daya Bay reactor neutrino experiment which is currently under construction. It is found that the Earth matter effects depend on the neutrino incident angle $\\theta$, the neutrino mass hierarchy $\\Delta m_{31}^{2}$, the crossing probability at the high resonance region inside the supernova, $P_{H}$, the neutrino temperature, $T_{\\alpha}$, and the pinching parameter in the neutrino spectrum, $\\eta_{\\alpha}$. We also take into account the collective effects due to neutrino-neutrino interactions inside the supernova. With the expression for the dependence of $P_H$ on the neutrino mixing angle $\\theta_{13}$, we obtain the relations between $\\theta_{13}$ and the event numbers for various reaction channels of supernova neutrinos. Using these relations, we propose a possible method to acquire information about $\\theta_{13}$ smaller than $1.5^\\circ$. Such a sensitivity cannot yet be achieved by the Daya Bay reactor neutrino experiment which has a sensitivity of the order of $\\theta_{13}\\sim 3^\\circ$. Furthermore, we apply this method to other neutrino experiments, i.e. Super-K, SNO, KamLAND, LVD, MinBooNE, Borexino, and Double-Chooz. We also study the energy spectra of the differential event numbers, ${\\rm d}N/{\\rm d}E$.
Sterile Neutrino Fits to Short-Baseline Neutrino Oscillation Measurements
Conrad, J. M.
2013-01-01T23:59:59.000Z
This paper reviews short-baseline oscillation experiments as interpreted within the context of one, two, and three sterile neutrino models associated with additional neutrino mass states in the ~1?eV range. Appearance and ...
Super-Kamiokande atmospheric neutrinos: Status of subdominant oscillations
G. L. Fogli; E. Lisi; A. Marrone
2001-05-15T23:59:59.000Z
In the context of the recent (79.5 kTy) Super-Kamiokande atmospheric neutrino data, we concisely review the status of muonic-tauonic flavor oscillations and of the subdominant electron or sterile neutrino mixing, in schemes with three or four families and one dominant mass scale. In the three-family case, where we include the full CHOOZ spectral data, we also show, through a specific example, that ``maximal'' violations of the one-dominant mass scale approximation are not ruled out yet.
Effective Majorana Mass and Neutrinoless Double Beta Decay
Benato, Giovanni
2015-01-01T23:59:59.000Z
The probability distribution for the effective Majorana mass as a function of the lightest neutrino mass in the standard three neutrino scheme is computed via a random sampling from the distributions of the involved mixing angles and squared mass diffences. A flat distribution in the [0,2pi] range for the Majorana phases is assumed, and the dependence of small values of the effective mass on the Majorana phases is highlighted. The study is then extended with the addition of the cosmological bound on the sum of the neutrino masses. Finally, the prospects for neutrinoless double beta decay search with 76Ge, 130Te and 136Xe are discussed, as well as those for the measurement of the electron neutrino mass.
Effective Majorana Mass and Neutrinoless Double Beta Decay
Giovanni Benato
2015-10-05T23:59:59.000Z
The probability distribution for the effective Majorana mass as a function of the lightest neutrino mass in the standard three neutrino scheme is computed via a random sampling from the distributions of the involved mixing angles and squared mass diffences. A flat distribution in the [0,2pi] range for the Majorana phases is assumed, and the dependence of small values of the effective mass on the Majorana phases is highlighted. The study is then extended with the addition of the cosmological bound on the sum of the neutrino masses. Finally, the prospects for neutrinoless double beta decay search with 76Ge, 130Te and 136Xe are discussed, as well as those for the measurement of the electron neutrino mass.
The Solar Neutrino Day/Night Effect in Super-Kamiokande
Michael Burghard Smy; for the Super-Kamiokande Collaboration
2003-10-31T23:59:59.000Z
The time variation of the elastic scattering rate of solar neutrinos with electrons in Super-Kamiokande-I was fit to the day/night variations expected from active two-neutrino oscillations in the Large Mixing Angle region. Combining Super-Kamiokande measurements with other solar and reactor neutrino data, the mixing angle is determined as sin^2theta=0.276+0.033-0.026 and the mass squared difference between the two neutrino mass eigenstates as Delta m^2=7.1+0.6-0.5x10^-5eV^2. For the best fit parameters, a day/night asymmetry of -1.7+-1.6(stat)+1.3-1.2(syst)% was determined from the Super-Kamiokande data, which has improved statistical precision over previous measurements and is in excellent agreement with the expected value of -1.6%.
Are neutrinos their own antiparticles?
Kayser, Boris; /Fermilab
2009-03-01T23:59:59.000Z
We explain the relationship between Majorana neutrinos, which are their own antiparticles, and Majorana neutrino masses. We point out that Majorana masses would make the neutrinos very distinctive particles, and explain why many theorists strongly suspect that neutrinos do have Majorana masses. The promising approach to confirming this suspicion is to seek neutrinoless double beta decay. We introduce a toy model that illustrates why this decay requires nonzero neutrino masses, even when there are both right-handed and left-handed weak currents.
mixing and will provide important input for interpretation of next-generation neutrinoless double beta decay experiments. Measurement of the mass hierarchy is important input to the search for leptonic CP
Li, Yu-Feng
2014-01-01T23:59:59.000Z
We discuss reactor antineutrino oscillations with non-standard interactions (NSIs) at the neutrino production and detection processes. The neutrino oscillation probability is calculated with a parametrization of the NSI parameters by splitting them into the averages and differences of the production and detection processes respectively. The average parts induce constant shifts of the neutrino mixing angles from their true values, and the difference parts can generate the energy (and baseline) dependent corrections to the initial mass-squared differences. We stress that only the shifts of mass-squared differences are measurable in reactor antineutrino experiments. Taking Jiangmen Underground Neutrino Observatory (JUNO) as an example, we analyze how NSIs influence the standard neutrino measurements and to what extent we can constrain the NSI parameters.
Neutrino propagation in nuclear medium and neutrinoless double-beta decay
Kovalenko, S; Simkovic, F
2013-01-01T23:59:59.000Z
We discuss a novel effect in neutrinoless double beta decay related with the fact that its underlying mechanisms take place in the nuclear matter environment. We study a particular case of neutrino exchange mechanism and demonstrate possible impact of nuclear medium via Lepton Number Violating (LNV) 4-fermion neutral current interactions of neutrino with quarks from decaying nucleus. The net effect of these interactions is generation of an effective in-medium Majorana neutrino mass matrix. We calculate the corresponding effective masses and construct the neutrino mixing matrix in nuclear medium for the complete set of the relevant 4-fermion neutrino-quark operators. Using the experimental data on neutrinoless double beta decay in combination with the cosmological and tritium beta decay data we evaluate lower limits on the characteristic scales of the studied 4-fermion operators. For the LNV scale we have > 2.4 TeV.
Theory of Neutrinos: a White Paper
Mohapatra, R.N.; Antusch, S.; Babu, K.S.; Barenboim, G.; Chen, Mu-Chun; Davidson, S.; de Gouvea, A.; de Holanda, P.; Dutta, Bhaskar; Grossman, Y.; Joshipura, A.; Kayser,; Kersten, J.; Keum, Y.Y.; King, S.F.; Langacker, P.; Lindner, M.; Loinaz, W.; Masina, I.; Mocioiu, I.; Mohanty, S.; /Maryland U. /Madrid, Autonoma U. /Southampton U. /Oklahoma
2006-01-11T23:59:59.000Z
During 2004, four divisions of the American Physical Society commissioned a study of neutrino physics to take stock of where the field is at the moment and where it is going in the near and far future. Several working groups looked at various aspects of this vast field. The summary was published as a main report entitled ''The Neutrino Matrix'' accompanied by short 50 page versions of the report of each working group. Theoretical research in this field has been quite extensive and touches many areas and the short 50 page report [1] provided only a brief summary and overview of few of the important points. The theory discussion group felt that it may be of value to the community to publish the entire study as a white paper and the result is the current article. After a brief overview of the present knowledge of neutrino masses and mixing and some popular ways to probe the new physics implied by recent data, the white paper summarizes what can be learned about physics beyond the Standard Model from the various proposed neutrino experiments. It also comments on the impact of the experiments on our understanding of the origin of the matter-antimatter asymmetry of the Universe and the basic nature of neutrino interactions as well as the existence of possible additional neutrinos. Extensive references to original literature are provided.
Theory of neutrinos: A White paper
Mohapatra, R.N.; Antusch, S.; Babu, K.S.; Barenboim, G.; Chen, Mu-Chun; Davidson, S.; de Gouvea, A.; de Holanda, P.; Dutta, Bhaskar; Grossman, Y.; Joshipura, A.; Kayser,; Kersten, J.; Keum, Y.Y.; King, S.F.; Langacker, P.; Lindner, M.; Loinaz, W.; Masina, I.; Mocioiu, I.; Mohanty, S.; /Maryland U. /Madrid, Autonoma U. /Southampton U. /Oklahoma
2005-10-01T23:59:59.000Z
During 2004, four divisions of the American Physical Society commissioned a study of neutrino physics to take stock of where the field is at the moment and where it is going in the near and far future. Several working groups looked at various aspects of this vast field. The summary was published as a main report entitled ''The Neutrino Matrix'' accompanied by short 50 page versions of the report of each working group. Theoretical research in this field has been quite extensive and touches many areas and the short 50 page report [1] provided only a brief summary and overview of few of the important points. The theory discussion group felt that it may be of value to the community to publish the entire study as a white paper and the result is the current article. After a brief overview of the present knowledge of neutrino masses and mixing and some popular ways to probe the new physics implied by recent data, the white paper summarizes what can be learned about physics beyond the Standard Model from the various proposed neutrino experiments. It also comments on the impact of the experiments on our understanding of the origin of the matter-antimatter asymmetry of the Universe and the basic nature of neutrino interactions as well as the existence of possible additional neutrinos. Extensive references to original literature are provided.
Electromagnetic properties of massive neutrinos
Dobrynina, A. A., E-mail: aleksandradobrynina@rambler.ru; Mikheev, N. V.; Narynskaya, E. N. [Demidov Yaroslavl State University (Russian Federation)] [Demidov Yaroslavl State University (Russian Federation)
2013-10-15T23:59:59.000Z
The vertex function for a virtual massive neutrino is calculated in the limit of soft real photons. A method based on employing the neutrino self-energy operator in a weak external electromagnetic field in the approximation linear in the field is developed in order to render this calculation of the vertex function convenient. It is shown that the electric charge and the electric dipole moment of the real neutrino are zero; only the magnetic moment is nonzero for massive neutrinos. A fourth-generation heavy neutrino of mass not less than half of the Z-boson mass is considered as a massive neutrino.
Restrictions on the lifetime of sterile neutrinos from primordial nucleosynthesis
Ruchayskiy, Oleg [Physics Department, Theory Division, CERN, CH-1211 Geneva 23 (Switzerland); Ivashko, Artem, E-mail: oleg.ruchayskiy@epfl.ch, E-mail: ivashko@lorentz.leidenuniv.nl [Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, Niels Bohrweg 2, Leiden (Netherlands)
2012-10-01T23:59:59.000Z
We analyze the influence of sterile neutrinos with the masses in the MeV range on the primordial abundances of Helium-4 and Deuterium. We solve explicitly the Boltzmann equations for all particle species, taking into account neutrino flavour oscillations and demonstrate that the abundances are sensitive mostly to the sterile neutrino lifetime and only weakly to the way the active-sterile mixing is distributed between flavours. The decay of these particles also perturbs the spectra of (decoupled) neutrinos and heats photons, changing the ratio of neutrino to photon energy density, that can be interpreted as extra neutrino species at the recombination epoch. We derive upper bounds on the lifetime of sterile neutrinos based on both astrophysical and cosmological measurements of Helium-4 and Deuterium. We also demonstrate that the recent results of Izotov and Thuan [1], who find 2? higher than predicted by the standard primordial nucleosynthesis value of Helium-4 abundance, are consistent with the presence in the plasma of sterile neutrinos with the lifetime 0.01–2 seconds.
Reconciling Super-Kamiokande, LSND, and Homestake neutrino-oscillation data
D. V. Ahluwalia
1998-08-26T23:59:59.000Z
The L/E-flatness of the e-like events observed in the recent atmospheric-neutrino data from Super-Kamiokande (SuperK) is interpreted to reflect a new symmetry of the neutrino-oscillation mixing matrix. From that we obtain an analytical set of constraints yielding a class of mixing matrices of the property to simultaneously fit both the SuperK and the LSND data. The resulting mass squared difference relevant for the LSND experiment is found as 0.3 eV^2. The discussed symmetry, e.g., carries the nature that expectation values of masses for \
Resonant conversion of massless neutrinos in supernovae
Nunokawa, H; Rossi, A; Valle, José W F
1996-01-01T23:59:59.000Z
It has been noted for a long time that, in some circumstances, {\\sl massless} neutrinos may be {\\sl mixed} in the leptonic charged current. Conventional neutrino oscillation searches in vacuum are insensitive to this mixing. We discuss the effects of resonant massless-neutrino conversions in the dense medium of a supernova. In particular, we show how the detected \\bar\
Physics of neutrino flavor transformation through matter-neutrino resonances
Wu, Meng-Ru; Qian, Yong-Zhong
2015-01-01T23:59:59.000Z
In astrophysical environments such as core-collapse supernovae and neutron star-neutron star or neutron star-black hole mergers where dense neutrino media are present, matter-neutrino resonances (MNRs) can occur when the neutrino propagation potentials due to neutrino-electron and neutrino-neutrino forward scattering nearly cancel each other. We show that neutrino flavor transformation through MNRs can be explained by multiple adiabatic solutions similar to the Mikheyev-Smirnov-Wolfenstein mechanism. We find that for the normal neutrino mass hierarchy, neutrino flavor evolution through MNRs can be sensitive to the shape of neutrino spectra and the adiabaticity of the system, but such sensitivity is absent for the inverted hierarchy.
Estimating matter induced CPT violation in Long-Baseline Neutrino Experiments
Monika Randhawa; Mandip Singh; Manmohan Gupta
2014-12-16T23:59:59.000Z
We examine matter induced CPT violation effects in long baseline electron neutrino appearance experiments in a low energy neutrino factory setup. Assuming CPT invariance in vacuum, the magnitude of CPT violating asymmetry in matter has been estimated using the exact expressions for the transition probabilities. The dependence of the asymmetry on the oscillation parameters like mixing angles, mass squared differences as well as on the Dirac CP violating phase has been investigated.
Accounting for the Unresolved X-ray Background with Sterile Neutrino Dark Matter
Daniel Cumberbatch; Joseph Silk
2007-09-03T23:59:59.000Z
We consider a scenario where keV sterile neutrinos constitute all of the currently inferred dark matter abundance, whose radiative decays could potentially account for the flux contributions to the X-ray background attributed to unresolved sources. Here we apply integrated flux methods to results from the observations of the North and South Chandra deep fields in order to deduce constraints on the sterile neutrino mass-mixing parameters.