WorldWideScience

Sample records for active-unsterile neutrino mixing

  1. Democratic Neutrino Mixing Reexamined

    Fritzsch, Harald; Fritzsch, Harald; Xing, Zhi-zhong

    2004-01-01

    We reexamine the democratic neutrino mixing ansatz, in which the mass matrices of charged leptons and Majorana neutrinos arise respectively from the explicit breaking of S(3)_L x S(3)_R and S(3) flavor symmetries. It is shown that a democracy term in the neutrino sector can naturally allow the ansatz to fit the solar neutrino mixing angle \\theta_sun \\approx 33^\\circ. We predict \\sin^2 2\\theta_atm \\approx 0.95 for atmospheric neutrino mixing and J \\approx 1.2% for leptonic CP violation in neutrino oscillations without any fine-tuning. Direct relations between the model parameters and experimental observables are also discussed.

  2. Neutrinos Mass and Mixing

    González-Garciá, M Concepción

    1998-01-01

    I review the status of neutrino masses and mixings in the light of the solar and atmospheric neutrino data. The result from the LSND experiment and the possible role of neutrinos as hot dark matter are also included. I also discuss the simplest schemes proposed to reconcile these data which include a light sterile neutrino in addition to the three standard ones. Implications for future experiments are commented.

  3. Modulated bimaximal neutrino mixing

    Roy, Subhankar

    2016-01-01

    The present article is an endeavor to look into some fruitful frameworks based on "Bi-maximal" neutrino mixing, from a model independent stand. The possibilities involving the correction or attenuation of the original BM mixing matrix, followed by GUT-inspired charged lepton correction are invoked. The "symmetry-basis" thus constructed, accentuates some interesting facets such as: a modified QLC relation, $\\theta_{12}+\\theta_{c}\\approx\\frac{\\pi}{4}-\\theta_{13}\\cos(n\\pi-\\delta_{CP})$, a possible link up between neutrino and charged lepton sectors, $\\theta_{13}^{\

  4. Remarks upon neutrino mixing hypothesis

    It is shown that various versions of the neutrino mixing hypothesis and theoretical descriptions are in contradiction with generally accepted facts and principles. The possible alternative formulation of the neutrino oscillation theory there is also presented and it is shown under what conditions this theory reproduces the known oscillation probability formula. In our approach (flavor) neutrinos are Dirac particles. In the case of Majorana neutrinos, or the nonrelativistic neutrinos (i.e. relic neutrinos), the problem could be more complicated. (Authors)

  5. Theory of neutrino masses and mixing

    Smirnov, Alexei Yu

    2014-01-01

    In spite of enormous experimental progress in determination of the neutrino parameters, theory of neutrino mass and mixing is still on the cross-roads. Guidelines could be (i) the connection between zero neutrino charges (and therefore a possibility to be Majorana particle), smallness of the neutrino mass and large lepton mixing, (ii) joint description of leptons and quarks, (iii) existence of the right handed (RH) neutrinos without special quantum numbers. Properties of the RH neutrinos and the UV completion of the seesaw may turn out to be the key to understand the neutrino mass and mixing. In view of the LHC results minimalistic scenarios like $\

  6. Supernova constraints on neutrino mass and mixing

    Srubabati Goswami

    2000-01-01

    In this article I review the constraints on neutrino mass and mixing coming from type-II supernovae. The bounds obtained on these parameters from shock reheating, -process nucleosynthesis and from SN1987A are discussed. Given the current constraints on neutrino mass and mixing the effect of oscillations of neutrinos from a nearby supernova explosion in future detectors will also be discussed.

  7. Neutrino mixing with and without scalars

    We briefly summarize the results of neutrino mixing in SO(10). This is a prototype of a grand unified theory which utilizes spontaneous symmetry breaking with Higgs scalars. Then, we combine grand unified symmetry with extended technicolor symmetry and obtain neutrino mixing in the framework of dynamical symmetry breaking without Higgs scalars. Finally, we discuss gauge boson masses and neutrino mixing with scalars in an 0(4) x U(1) gauge model

  8. Neutrino masses and mixing in supersymmetric theories

    Sudhir K Vempati

    2000-07-01

    It has been known for sometime that supersymmetric theories with -parity violation provide a natural framework where small neutrino masses can be generated. We discuss neutrino masses and mixing in these theories in the presence of trilinear lepton number violating couplings. It will be shown that simultaneous solutions to solar and atmospheric neutrino problems can be realized in these models.

  9. Neutrino masses from an approximate mixing matrix with $\\theta_{13}\

    Damanik, Asan

    2016-01-01

    An approximate neutrino mixing matrix is formutated by using the standard neutrino mixing matrix as a basis and experimental data of neutrino oscillations as inputs. By using the resulted approximate neutrino mixing matrix to proceed the neutrino mass matrix and constraining the resulted neutrino mass matrix with zero texture: $M_{\

  10. Neutrino oscillations and the maximal mixing scenario

    The problem of neutrino oscillation is considered in the plane wave formalism, as well as in the full wave packet quantum mechanics language. It is shown that Lorentz invariance implies that in general, flavour neutrinos in oscillation experiments are superpositions of massive neutrinos with different energies and different momenta. The hypothesis of threefold-maximal neutrino mixing is investigated and the implications on the coherence of the states is analysed. (authors)

  11. Rephasing invariant parametrization for neutrino mixing

    Chiu, S.H., E-mail: schiu@mail.cgu.edu.tw [Physics Group, CGE, Chang Gung University, Kwei-Shan 333, Taiwan (China); Kuo, T.K., E-mail: tkkuo@purdue.edu [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)

    2012-08-15

    The neutrino mixing in matter is studied under the three-flavor framework with a rephrasing invariant parametrization. The evolution equations for the parameters as functions of the induced neutrino mass are derived. They are found to preserve approximately some characteristic features of the mixing matrix, resulting in solutions which exhibit striking patterns as the induced mass varies.

  12. Rephasing invariant parametrization for neutrino mixing

    The neutrino mixing in matter is studied under the three-flavor framework with a rephrasing invariant parametrization. The evolution equations for the parameters as functions of the induced neutrino mass are derived. They are found to preserve approximately some characteristic features of the mixing matrix, resulting in solutions which exhibit striking patterns as the induced mass varies.

  13. Neutrino Mixing and Leptonic CP Phase in Neutrino Oscillations

    Ryzhikh, D. A.; Ter-Martirosyan, K. A.

    2001-01-01

    Oscillations of the Dirac neutrinos of three generations in vacuum are considered with allowance made for the effect of the CP-violating leptonic phase (analogue of the quark CP phase) in the lepton mixing matrix. The general formulas for the probabilities of neutrino transition from one sort to another in oscillations are obtained as functions of three mixing angles and the CP phase. It is found that the leptonic CP phase can, in principle, be reconstructed by measuring the oscillation-avera...

  14. Neutrino mass and mixing: Summary of the neutrino sessions

    A great deal of experimental and theoretical effort is underway to use neutrinos as a probe for Physics Beyond the Standard Model. Most of these efforts center on the questions of the possible existence of non zero neutrino mass and mixing. Sessions at the Moriond conferences have dealt with these questions at most of the meetings during the last several years and this year was no exception. Presentations covering most of the current and planned research in this field were presented and discussed. Although there is, at present, no definitive evidence for a non zero neutrino mass and mixing, several unresolved problems (in particular solar neutrinos) do seem to be indicating the likely existence of new neutrino properties. It is likely that before the end of this decade, efforts now being initiated will be able to determine whether or not the hints we are now seeing are really due to new physics

  15. Massive neutrinos flavor mixing of leptons and neutrino oscillations

    2015-01-01

    Since the discovery of neutrino oscillations neutrino physics has become an interesting field of research in physics. They imply that neutrino must have a small mass and that the neutrinos, coupled to the charged leptons, are mixtures of the mass eigenstates, analogous to the flavor mixing of the quarks. The mixing angles for the quarks are small, but for the leptons two of the mixing angles are large. The masses of the three neutrinos must be very small, less than 1 eV, but from the oscillation experiments we only know the mass differences — the absolute masses are still unknown. Also we do not know, if the masses of the neutrinos are Dirac masses, as the masses of the charged leptons and of the quarks, or whether they are Majorana masses. In this volume, an overview of the present state of research in neutrino physics is given by well-known experimentalists and theorists. The contents — originated from talks and discussions at a recent conference addressing some of the most pressing open questions in n...

  16. Neutrino Masses and Mixings in SO(10)

    Abud, M.; Buccella, F.; Tramontano, F.; Falcone, D.; Ricciardi, G.

    Assuming a Zee-like matrix for the right-handed neutrino Majorana masses in the seesaw mechanism, one gets maximal mixing for vacuum solar oscillations, a very small value for Ue3 and an approximate degeneracy for the two lower neutrino masses. The scale of right-handed neutrino Majorana masses is in good agreement with the value expected in an SO(10) model with Pati-Salam SU(4)×SU(2)×SU(2) intermediate symmetry.

  17. Neutrino masses and mixings in SO(10)

    Abud, M; Falcone, D; Ricciardi, G; Tramontano, Francesco

    2000-01-01

    Assuming a Zee-like matrix for the right-handed neutrino Majorana masses in the see-saw mechanism, one gets maximal mixing for vacuum solar oscillations, a very small value for U_{e3} and an approximate degeneracy for the two lower neutrino masses. The scale of right-handed neutrino Majorana masses is in good agreement with the value expected in a SO(10) model with Pati-Salam $SU(4)\\ts SU(2)\\ts SU(2)$ intermediate symmetry.

  18. Neutrino mass and mixing: 2006 status

    We review the current status (as of the end of 2006) of neutrino mass and mixing determinations, putting the accent on the impact of recent neutrino oscillation and non-oscillation data. In particular, we discuss the improvement on the constraints coming from the first Main Injector Neutrino Oscillation Search (MINOS) results, the Wilkinson Microwave Anisotropy Probe (WMAP) three-year (3y) data, and other new relevant cosmological information

  19. Constraints on three flavor neutrino mixing

    Mohan Narayan

    2000-01-01

    We summarize the constraints on three flavor neutrino mixing coming from data. We first map out the allowed region in the three neutrino parameter space using solar and atmospheric neutrino data. We then incorporate the results of reactor and long baseline experiments in our analysis and show that the parameter space is drastically reduced. We conclude by pointing out that the results of Borexino and SNO will further help in constraining the parameter space.

  20. Neutrino mixing and lepton CP-phase in neutrino oscillations

    One studied oscillations of the Dirac neutrinos belonging to three generations in vacuum with regard to the effect of the lepton CP-breaking phase on them in the matrix of lepton mixing (analogue of the quark CP-phase). In the general form one obtained formulae for probabilities of transition of neutrino of one kind to another at oscillations depending on three angles of mixing and on CP-phase. It was pointed that when measuring oscillation average probabilities of transition of neutrino of one kind to another one might in principle, restore the value of lepton CP-phase. Manifestation of CP-phase in the form of deviation of the values of probabilities of direct neutrino transition from reverse one is the effect practically escaping observation

  1. A rephasing invariant study of neutrino mixing

    Chiu, S H

    2015-01-01

    We derive a set of renormalization group equations (RGE) for Dirac neutrinos using a rephasing invariant parametrization. The symmetric properties of these equations under flavor permutation facilitate the derivation of some exact and approximate RGE invariants. Even though the complete analytical solutions for the RGE are unavailable, we provide a numerical example that illustrate the evolution of the neutrino mixing parameters.

  2. Dark energy, cosmological constant and neutrino mixing

    A. Capolupo; Capozziello, S.; Vitiello, G.

    2007-01-01

    The today estimated value of dark energy can be achieved by the vacuum condensate induced by neutrino mixing phenomenon. Such a tiny value is recovered for a cut-off of the order of Planck scale and it is linked to the sub eV neutrino mass scale. Contributions to dark energy from auxiliary fields or mechanisms are not necessary in this approach.

  3. Neutrino mass and mixing – status

    Thomas Schwetz

    2012-11-01

    The status of neutrino oscillations from global data are summarized. An update on the three-flavour picture and recent developments are discussed with regard to the measurement of the mixing angle 13. Global data currently provide an indication at 3 that 13 is non-zero. Furthermore, the status of sterile neutrino oscillation interpretations of the LSND anomaly in the light of MiniBooNE results and a recent re-evaluation of the neutrino fluxes from nuclear reactors are discussed. Despite several hints for sterile neutrinos at the eV scale, there is severe tension in the global data and no consistent description of all data is possible.

  4. Deviations in Tribimaximal Mixing From Sterile Neutrino Sector

    Dev, S; Gautam, Radha Raman

    2016-01-01

    We explore the possibility of generating a non-zero $U_{e3}$ element of the neutrino mixing matrix from tribimaximal neutrino mixing by adding a light sterile neutrino to the active neutrinos. Small active-sterile mixing can provide the necessary deviation from tribimaximal mixing to generate a non-zero $\\theta_{13}$ and atmospheric mixing $\\theta_{23}$ different from maximal. Assuming no CP-violation, we study the phenomenological impact of sterile neutrinos in the context of current neutrino oscillation data. The tribimaximal pattern is broken in such a manner that the second column of tribimaximal mixing remains intact in the neutrino mixing matrix.

  5. Two Component Theory of Neutrino Flavor Mixing

    Sassaroli, Elisabetta

    1997-01-01

    Neutrino flavor mixing is discussed in terms of two-component coupled left-handed flavor fields. This is to take into account the fact that the weak interaction couples only to left-handed fields. The flavor fields are written through a rotation matrix, as a linear combination of left-handed free fields. In order to obtain properly normalized wave functions directly from those free fields, states of mixed helicity have to be considered. Neutrino flavor oscillation amplitudes are also derived.

  6. Three-neutrino mixing: status and prospects

    Marrone, A.; Capozzi, F.; Lisi, E.; Montanino, D.; Palazzo, A.

    2016-05-01

    We discuss the present knowledge of the neutrino oscillation parameters. In a three-neutrino scenario, neutrino oscillations depend on six parameters, two squared mass differences (Δm2, δm2), three mixing angles (θ 12, θ13 , θ 23) and one phase δ. While five out of these six parameters have been measured, the CP-violating phase δ remains unknown. Moreover, the octant of the mixing angle θ23 and the neutrino mass hierarchy are still undetermined. We update our previous analysis, by adding to the global fit the recent results of the antineutrino running of T2K, the first results of the NOvA experiment, the latest SuperKamiokande and IceCube atmospheric neutrino data.

  7. Large Solar Neutrino Mixing and Radiative Neutrino Mechanism

    Kitabayashi, T; Kitabayashi, Teruyuki; Yasue, Masaki

    2002-01-01

    We find that the presence of a global $L_e-L_\\mu-L_\\tau$ ($\\equiv L^\\prime$) symmetry and an $S_2$ permutation symmetry for the $\\mu$- and $\\tau$-families supplemented by a discrete $Z_4$ symmetry naturally leads to almost maximal atmospheric neutrino mixing and large solar neutrino mixing, which arise, respectively, from type II seesaw mechanism initiated by an $S_2$-symmetric triplet Higgs scalar $s$ with $L^\\prime=2$ and from radiative mechanism of the Zee type initiated by two singly charged scalars, an $S_2$-symmetric $h^+$ with $L^\\prime=0$ and an $S_2$-antisymmetric $h^{\\prime +}$ with $L^\\prime=2$. The almost maximal mixing for atmospheric neutrinos is explained by the appearance of the democratic coupling of $s$ to neutrinos ensured by $S_2$ and $Z_4$ while the large mixing for solar neutrinos is explained by the similarity of $h^+$- and $h^{\\prime +}$-couplings described by $f^h_+\\sim f^h_-$ and $\\mu_+\\sim\\mu_-$, where $f^h_+$ ($f^h_-$) and $\\mu_+$ ($\\mu_-$) stand for $h^+$ ($h^{\\prime +}$)-coupling...

  8. Large Neutrino Mixing from Renormalization Group Evolution

    Balaji, K R S; Parida, M K; Paschos, E A

    2001-01-01

    The renormalization group evolution equation for two neutrino mixing is known to exhibit nontrivial fixed point structure corresponding to maximal mixing at the weak scale. The presence of the fixed point provides a natural explanation of the observed maximal mixing of $\

  9. Examination of pairs in neutrino mixing matrix

    Liu, Dianjing

    2015-01-01

    We exam the pairs of neutrino mixing matrix and suggest pairs that can be used in the construction of new mixing patterns, with "pair" denoting the equality of the modulus of a pair of matrix elements. The results show that the tri-maximal mixing in $\

  10. Parameterization for Neutrino Mixing Matrix with Deviated Unitarity

    LU Lei; WANG Wen-Yu; XIONG Zhao-Hua

    2009-01-01

    Neutrino oscillation experiments provide the first evidence on non-zero neutrino masses and indicate new physics beyond the standard model.With Majorana neutrinos introduced to acquire tiny neutrino maases,it leads to the existence of more than three neutrino species,implying that the ordinary neutrino mixing matrix is only a part of the whole extended unitary mixing matrix and thus no longer unitary.We give a parameterization for a non-unitary neutrino mixing matrix under seesaw framework and further present a method to test the unitarity of the ordinary neutrino mixing matrix.

  11. Global constraints on heavy neutrino mixing

    Fernandez-Martinez, Enrique; Lopez-Pavon, Jacobo

    2016-01-01

    We derive general constraints on the mixing of heavy Seesaw neutrinos with the SM fields from a global fit to present flavour and electroweak precision data. We explore and compare both a completely general scenario, where the heavy neutrinos are integrated out without any further assumption, and the more constrained case were only 3 additional heavy states are considered. The latter assumption implies non-trivial correlations in order to reproduce the correct neutrino masses and mixings as observed by oscillation data and thus some qualitative differences can be found with the more general scenario. The relevant processes analyzed in the global fit include searches for Lepton Flavour Violating (LFV) decays, probes of the universality of weak interactions, CKM unitarity bounds and electroweak precision data. In particular, a comparative and detailed study of the present and future sensitivity of the different LFV experiments is performed. We find a mild $1-2\\sigma$ preference for non-zero heavy neutrino mixin...

  12. Lepton Mass Hierarchy and Neutrino Mixing

    Fritzsch, Harald; Xing, Zhi-zhong

    2006-01-01

    We speculate that the mass spectrum of three neutrinos might have a normal hierarchy as that of three charged leptons or that of three up-type (or down-type) quarks. In this spirit, we propose a novel parametrization of the $3\\times 3$ lepton flavor mixing matrix. Its mixing angles $\\theta_l$ and $\\theta_\

  13. On entanglement in neutrino mixing and oscillations

    We report on recent results about entanglement in the context of particle mixing and oscillations. We study in detail single-particle entanglement arising in two-flavor neutrino mixing. The analysis is performed first in the context of Quantum Mechanics, and then for the case of Quantum Field Theory.

  14. On entanglement in neutrino mixing and oscillations

    Blasone, M.; Dell'Anno, F.; De Siena, S.; Illuminati, F.

    2010-01-01

    We report on recent results about entanglement in the context of particle mixing and oscillations. We study in detail single-particle entanglement arising in two-flavor neutrino mixing. The analysis is performed first in the context of Quantum Mechanics, and then for the case of Quantum Field Theory.

  15. On entanglement in neutrino mixing and oscillations

    Blasone, Massimo; Dell' Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio, E-mail: blasone@sa.infn.i [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)

    2010-06-01

    We report on recent results about entanglement in the context of particle mixing and oscillations. We study in detail single-particle entanglement arising in two-flavor neutrino mixing. The analysis is performed first in the context of Quantum Mechanics, and then for the case of Quantum Field Theory.

  16. Democratic Neutrino Mixing and Radiative Corrections

    Xing, Zhi-zhong

    2000-01-01

    The renormalization effect on a specific ansatz of lepton mass matrices, arising naturally from the breaking of flavor democracy for charged leptons and that of mass degeneracy for light neutrinos, is studied from a superhigh energy scale M_0 \\sim 10^{13} GeV to the electroweak scale in the framework of the minimal supersymmetric standard model. We find that the democratic neutrino mixing pattern obtained from this ansatz may in general be instable against radiative corrections. With the help...

  17. Structures of neutrino flavor mixing matrix and neutrino oscillations at CHORUS and NOMAD

    We study structures of the neutrino flavor mixing matrix focusing on the neutrino oscillations at CHORUS and NOMAD as well as the one at LSND (or KARMEN). We assume two typical neutrino mass hierarchies m3≅m2>m1 and m3>m2>m1 (or ≅m1). Taking into account the seesaw mechanism of neutrino masses, reasonable neutrino flavor mixing patterns are discussed. The observation of the neutrino oscillation at CHORUS and NOMAD presents an important constraint for the structure of the neutrino flavor mixing matrix. The atmospheric neutrino anomaly is discussed in relation to the CHORUS and NOMAD experiments. copyright 1996 The American Physical Society

  18. Precise predictions of neutrino mixing angles and $CP$ phase

    Abbas, Gauhar

    2016-01-01

    The neutrino mixing parameters are studied using renormalization-group evolution of Dirac neutrinos with recently proposed parameterization of the neutrino mixing angles referred as `high-scale mixing relations'. The correlations among all neutrino mixing and $CP$ violating parameters are investigated. The predictions for the neutrino mixing angles and the $CP$ phase are precise and could be easily tested by ongoing and future experiments. We observe that the high scale mixing unification hypothesis is incompatible with Dirac neutrinos due to updated experimental data.

  19. Bounds on neutrino mixing with exotic singlet neutrinos

    J K Singhal; Sardar Singh; Ashok K Nagawat; N K Sharma

    2002-09-01

    We examine the effects of mixing induced non-diagonal light–heavy neutrino weak neutral currents on the amplitude for the process $v_{a}\\overline{v}_{a}→ ZZ$ (with $a = e$; or ). By imposing constraint that the amplitude should not exceed the perturbative unitarity limit at high energy $(\\sqrt{s}=)$, we obtain bounds on light–heavy neutrino mixing parameter $\\sin^{2}^{v_{a}}_{L}$ where $^{v_{a}}_{L}$ is the mixing angle. In the case of one heavy neutrino (mass $m_{}$) or mass degenerate heavy neutrinos, for $ = 1$ TeV, no bound is obtained for $m_{} < 0:50$ TeV. However, $\\sin^{2}^{v_{a}}_{L}≤ 3:8× 10^{-6}$ for $m_{} = 5$ TeV and $\\sin^{2} ^{v_{a}}_{L}≤ 6.0× 10^{-8}$ for $m_{} = 10$ TeV. For = ∞, no constraint is obtained for $m_{} < 0:99$ TeV and $\\sin^{2} ^{v_{a}}_{L}≤ 3.8× 10^{-2}$ (for $m_{} = 5$ TeV) and $\\sin^{2}^{v_{a}}_{L}≤ 9.6× 10^{-3}$ (for $m_{} = 10$ TeV).

  20. High Scale Mixing Unification for Dirac Neutrinos

    Abbas, Gauhar; Gupta, Saurabh; Rajasekaran, G.; Srivastava, Rahul(The Institute of Mathematical Sciences, Chennai, 600 113, India)

    2013-01-01

    Starting with high scale mixing unification hypothesis, we investigate the renormalization group evolution of mixing parameters and masses for Dirac type neutrinos. Following this hypothesis, the PMNS mixing angles and phase are taken to be identical to the CKM ones at a unifying high scale. Then, they are evolved to a low scale using renormalization-group equations. The notable feature of this hypothesis is that renormalization group evolution with quasi-degenerate mass pattern can explain l...

  1. Overview of Neutrino Mixing Models and Their Mixing Angle Predictions

    Albright, Carl H.

    2009-11-01

    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.

  2. $\\Delta(27)$ family symmetry and neutrino mixing

    Varzielas, Ivo de Medeiros

    2015-01-01

    The observed neutrino mixing, having a near maximal atmospheric neutrino mixing angle and a large solar mixing angle, is close to tri-bi-maximal. This structure may be related to the existence of a discrete non-Abelian family symmetry. In this paper the family symmetry is the non-Abelian discrete group $\\Delta(27)$, a subgroup of $SU(3)$ with triplet and anti-triplet representations. Different frameworks are constructed in which the mixing follows from combining fermion mass terms with the vacuum structure enforced by the discrete symmetry. Mass terms for the fermions originate from familon triplets, anti-triplets or both. Vacuum alignment for the family symmetry breaking familons follows from simple invariants.

  3. Neutrino mass and mixing with discrete symmetry

    King, Stephen F.; Luhn, Christoph

    2013-05-01

    This is a review paper about neutrino mass and mixing and flavour model building strategies based on discrete family symmetry. After a pedagogical introduction and overview of the whole of neutrino physics, we focus on the PMNS mixing matrix and the latest global fits following the Daya Bay and RENO experiments which measure the reactor angle. We then describe the simple bimaximal, tri-bimaximal and golden ratio patterns of lepton mixing and the deviations required for a non-zero reactor angle, with solar or atmospheric mixing sum rules resulting from charged lepton corrections or residual trimaximal mixing. The different types of see-saw mechanism are then reviewed as well as the sequential dominance mechanism. We then give a mini-review of finite group theory, which may be used as a discrete family symmetry broken by flavons either completely, or with different subgroups preserved in the neutrino and charged lepton sectors. These two approaches are then reviewed in detail in separate chapters including mechanisms for flavon vacuum alignment and different model building strategies that have been proposed to generate the reactor angle. We then briefly review grand unified theories (GUTs) and how they may be combined with discrete family symmetry to describe all quark and lepton masses and mixing. Finally, we discuss three model examples which combine an SU(5) GUT with the discrete family symmetries A4, S4 and Δ(96).

  4. Schemes and Mechanisms of Neutrino Mixings (Oscillations) and a Solution of the Sun Neutrinos Deficit Problem

    Beshtoev, Kh. M.

    2004-01-01

    Three schemes of neutrino mixings (oscillations) are proposed. The problems of origin of angle mixings, with the law of energy-momentum conservation and disintegration of neutrino as wave pocket are solved. These two schemes belong to mass mixings schemes, where mixing angles and oscillation lengths are expressed via elements of mass matrix. The third scheme belongs to the charge mixings scheme, where mixing parameters are expressed via neutrino weak charges, as it takes place in the vector d...

  5. Neutrino Mixing Discriminates Geo-reactor Models

    Dye, S T

    2009-01-01

    Geo-reactor models suggest the existence of natural nuclear reactors at different deep-earth locations with loosely defined output power. Reactor fission products undergo beta decay with the emission of electron antineutrinos, which routinely escape the earth. Neutrino mixing distorts the energy spectrum of the electron antineutrinos. Characteristics of the distorted spectrum observed at the earth's surface could specify the location of a geo-reactor, discriminating the models and facilitating more precise power measurement. The existence of a geo-reactor with known position could enable a precision measurement of the neutrino oscillation parameter delta-mass-squared.

  6. Neutrino Mass and Mixing with Discrete Symmetry

    King, Stephen F

    2013-01-01

    This is a review article about neutrino mass and mixing and flavour model building strategies based on discrete family symmetry. After a pedagogical introduction and overview of the whole of neutrino physics, we focus on the PMNS mixing matrix and the latest global fits following the Daya Bay and RENO experiments which measure the reactor angle. We then describe the simple bimaximal, tri-bimaximal and golden ratio patterns of lepton mixing and the deviations required for a non-zero reactor angle, with solar or atmospheric mixing sum rules resulting from charged lepton corrections or residual trimaximal mixing. The different types of seesaw mechanism are then reviewed as well as the sequential dominance mechanism. We then give a mini-review of finite group theory, which may be used as a discrete family symmetry broken by flavons either completely, or with different subgroups preserved in the neutrino and charged lepton sectors. These two approaches are then reviewed in detail in separate chapters including mec...

  7. Tri-Bimaximal Mixing and the Neutrino Oscillation Data

    Harrison, P F; Scott, W G

    2002-01-01

    Following recent results from the SNO solar neutrino experiment and the K2K long-baseline neutrino experiment, the combined existing data on neutrino oscillations now point strongly to a specific form for the lepton mixing matrix, with effective bimaximal mixing of $\

  8. Large neutrino mixing from renormalization group evolution

    The renormalization group evolution equation for two neutrino mixing is known to exhibit nontrivial fixed point structure corresponding to maximal mixing at the weak scale. The presence of the fixed point provides a natural explanation of the observed maximal mixing of νμ - ντ, if the νμ and ντ are assumed to be quasi-degenerate at the seesaw scale without constraining the mixing angles at that scale. In particular, it allows them to be similar to the quark mixings as in generic grand unified theories. We discuss implementation of this program in the case of MSSM and find that the predicted mixing remains stable and close to its maximal value, for all energies below the O(TeV) SUSY scale. We also discuss how a particular realization of this idea can be tested in neutrinoless double beta decay experiments. (author)

  9. Democratic Neutrino Mixing and Radiative Corrections

    Xing, Z

    2001-01-01

    The renormalization effect on a specific ansatz of lepton mass matrices, arising naturally from the breaking of flavor democracy for charged leptons and that of mass degeneracy for light neutrinos, is studied from a superhigh energy scale M_0 \\sim 10^{13} GeV to the electroweak scale in the framework of the minimal supersymmetric standard model. We find that the democratic neutrino mixing pattern obtained from this ansatz may in general be instable against radiative corrections. With the help of similar flavor symmetries we prescribe a slightly different scheme of lepton mass matrices at the scale M_0, from which the democratic mixing pattern of lepton flavors can be achieved, after radiative corrections, at the experimentally accessible scales.

  10. Democratic neutrino mixing and radiative corrections

    Xing, Zhi-Zhong

    2001-03-01

    The renormalization effect on a specific ansatz of lepton mass matrices, arising naturally from the breaking of flavor democracy for charged leptons and that of mass degeneracy for light neutrinos, is studied from a superhigh energy scale M0~1013 GeV to the electroweak scale in the framework of the minimal supersymmetric standard model. We find that the democratic neutrino mixing pattern obtained from this ansatz may in general be unstable against radiative corrections. With the help of similar flavor symmetries we prescribe a slightly different scheme of lepton mass matrices at the scale M0, from which the democratic mixing pattern of lepton flavors can be achieved, after radiative corrections, at the experimentally accessible scales.

  11. Neutrino Flavor Tagging in a Four-Neutrino Mixing and Oscillation Model

    Lipmanov, E M

    1999-01-01

    A neutrino mass dominance quantity is introduced for tagging the neutrino flavor in the phenomenological two-parameter four neutrino mixing matrix with two neutrino mass doublets and thorough maximal neutrino doublet mixing. While there is no hierarchy of the neutrino masses in the neutrino flavor eigenstates of this model, it may rather be a special hierarchy of the mass dominance ratios in these eigenstates. A neutrino flavor hierarchy condition is suggested: a direct link between the neutrino flavor and the flavor of the charged leptons which interconnects the two mixing angles, theta and phi, via the charged lepton mass ratios, with the net result tg^2 phi = (tg^2 theta)^gamma, gamma ~ 2.06. It leads to distinct inferences testable at SNO and Super-K.

  12. Theory of Neutrino Masses and Mixing

    González-Garciá, M Concepción

    2003-01-01

    In this talk I will review our present knowledge on neutrino masses and mixing trying to emphasize what has been definitively proved and what is in the process of being probed. I will also discuss the most important theoretical implications of these results: the existence of new physics, the estimate of the scale of this new physics as well as some other possible consequences such as leptogenesis origin of the baryon asymmetry.

  13. Small Violation of Universal Yukawa Coupling and Neutrino Large Mixing

    Teshima, T

    2001-01-01

    We assume the universal Yukawa coupling (democratic mass matrix) with small violations for quarks, charged leptons and neutrinos masses. We could reproduce the mass hierarchy for quark masses and V_{CKM} matrix elements precisely. We adopt the see-saw mechanism for the explanation of smallness of neutrino masses and introduce the right-handed Majorana neutrinos and Dirac neutrinos. We assume the universal Yukawa coupling with small violations for Majorana and Dirac neutrinos. We can get the hierarchy of charged lepton masses and effective neutrino masses and the large mixing of neutrinos expressed in V_{NMS}.

  14. Inverting a Supernova: Neutrino Mixing, Temperatures and Binding Energy

    Barger, V.; Marfatia, D.; Wood, B. P.

    2001-01-01

    We show that the temperatures of the emergent non-electron neutrinos and the binding energy released by a galactic Type II supernova are determinable, assuming the Large Mixing Angle (LMA) solution is correct, from observations at the Sudbury Neutrino Observatory (SNO) and at Super-Kamiokande (SK). If the neutrino mass hierarchy is inverted, either a lower or upper bound can be placed on the neutrino mixing angle $\\theta_{13}$, and the hierarchy can be deduced for adiabatic transitions. For t...

  15. Neutrino Masses and Mixing one Decade from Now

    González-Garciá, M Concepción

    2000-01-01

    We review the status of neutrino masses and mixings in the light of the solar and atmospheric neutrino data. The result from the LSND experiment is also considered. We discuss the present knowledge and the expected sensitivity to the neutrino mixing parameters in the simplest schemes proposed to reconcile these data some of which include a light sterile neutrino in addition to the three standard ones.

  16. Neutrinos and the hunt for the last mixing angle

    Neutrinos are the universe's second most common particles after photons. During their journey through space-time, the elusive neutrinos can change types through the phenomenon called neutrino oscillations. The hunt for the Θ13 mixing angle has mainly been taken up by 3 neutrino experiments: the Daya Bay experiment in China, the Double Chooz experiment in France and the RENO experiment in South-Korea. All 3 are reactor neutrino experiments, which examine electron antineutrinos from nuclear power plants to directly determine the value of Θ13. We have now 3 independent measurements from 3 different experiments which all indicate that the value of the mixing angle Θ13 is about 9 degrees. One of the 3 CP-violating phases, the so-called Dirac CP-violating phase δ, can be measured using neutrino oscillation experiments. This phase appears only in combination with the third mixing angle Θ13. Thus a non-zero value of Θ13 means that it is, in principle, possible to determine δ. Accelerator-based neutrino oscillation experiments will provide the most promising opportunity to observe CP violations by studying both neutrino and anti-neutrino oscillations. If anti-neutrinos do not oscillate in the same way as neutrino do, then this will be a signal of CP violation. The fact that neutrinos are massive and mixed means that the Standard Model must be modified to include massive and mixed neutrinos. (A.C.)

  17. Radiative magnification of neutrino mixings and a natural explanation of the neutrino anomalies

    Balaji, K R S; Mohapatra, Rabindra N; Parida, M K; Dighe, Amol S.

    2000-01-01

    We show that the neutrino mixing pattern with the large mixing required forthe atmospheric neutrino problem and the small mixing angle MSW solution forthe solar neutrino problem can be naturally generated through radiativemagnification, even though all the mixing angles at the seesaw scale may besmall. This can account for the neutrino anomalies as well as the CHOOZconstraints in the context of quark-lepton unified theories, where the quarkand lepton mixing angles are expected to be similar in magnitude at the highscale. We also indicate the 4$\

  18. Calculating error bars for neutrino mixing parameters

    Burroughs, H R; Escamilla-Roa, J; Latimer, D C; Ernst, D J

    2012-01-01

    One goal of contemporary particle physics is to determine the mixing angles and mass-squared differences that constitute the phenomenological constants that describe neutrino oscillations. Of great interest are not only the best fit values of these constants but also their errors. Some of the neutrino oscillation data is statistically poor and cannot be treated by normal (Gaussian) statistics. To extract confidence intervals when the statistics are not normal, one should not utilize the value for chisquare versus confidence level taken from normal statistics. Instead, we propose that one should use the normalized likelihood function as a probability distribution; the relationship between the correct chisquare and a given confidence level can be computed by integrating over the likelihood function. This allows for a definition of confidence level independent of the functional form of the !2 function; it is particularly useful for cases in which the minimum of the !2 function is near a boundary. We present two ...

  19. On non-unitary lepton mixing and neutrino mass observables

    There are three observables related to neutrino mass, namely the kinematic mass in direct searches, the effective mass in neutrino-less double beta decay, and the sum of neutrino masses in cosmology. In the limit of exactly degenerate neutrinos there are very simple relations between those observables, and we calculate corrections due to non-zero mass splitting. We discuss how the possible non-unitarity of the lepton mixing matrix may modify these relations and find in particular that corrections due to non-unitarity can exceed the corrections due to mass splitting. We furthermore investigate constraints from neutrino-less double beta decay on mass and mixing parameters of heavy neutrinos in the type I see-saw mechanism. There are constraints from assuming that heavy neutrinos are exchanged, and constraints from assuming light neutrino exchange, which arise from an exact see-saw relation. The latter has its origin in the unitarity violation arising in see-saw scenarios. We illustrate that the limits from the latter approach are much stronger. The drastic impact of the new limit on inverse neutrino-less double beta decay (e-e-→W-W-) is studied. We furthermore discuss neutrino mixing in case there is one or more light sterile neutrinos. Neutrino oscillation probabilities for long baseline neutrino oscillation experiments are considered, and the analogy to general non-unitarity phenomenology, such as zero-distance effects, is pointed out.

  20. Neutrino Mass and Mixing in the Seesaw Playground

    King, Stephen F

    2015-01-01

    We discuss neutrino mass and mixing in the framework of the classic seesaw mechanism, involving right-handed neutrinos with large Majorana masses, which provides an appealing way to understand the smallness of neutrino masses. However, with many input parameters, the seesaw mechanism is in general not predictive. We focus on natural implementations of the seesaw mechanism, in which large cancellations do not occur, where one of the right handed neutrinos is dominantly responsible for the atmospheric neutrino mass, while a second right-handed neutrino accounts for the solar neutrino mass, leading to an effective two right-handed neutrino model. We discuss recent attempts to predict lepton mixing and CP violation within such natural frameworks, focussing on the Littlest Seesaw and its distinctive predictions.

  1. Neutrino mass and mixing in the seesaw playground

    King, Stephen F.

    2016-07-01

    We discuss neutrino mass and mixing in the framework of the classic seesaw mechanism, involving right-handed neutrinos with large Majorana masses, which provides an appealing way to understand the smallness of neutrino masses. However, with many input parameters, the seesaw mechanism is in general not predictive. We focus on natural implementations of the seesaw mechanism, in which large cancellations do not occur, where one of the right-handed neutrinos is dominantly responsible for the atmospheric neutrino mass, while a second right-handed neutrino accounts for the solar neutrino mass, leading to an effective two right-handed neutrino model. We discuss recent attempts to predict lepton mixing and CP violation within such natural frameworks, focusing on the Littlest Seesaw and its distinctive predictions.

  2. On flavor violation for massive and mixed neutrinos

    We discuss flavor charges and states for interacting mixed neutrinos in QFT. We show that the Pontecorvo states are not eigenstates of the flavor charges. This implies that their use in describing the flavor neutrinos produces a violation of lepton charge conservation in the production/detection vertices. The flavor states defined as eigenstates of the flavor charges give the correct representation of mixed neutrinos in charged current weak interaction processes.

  3. Renormalisation Group Corrections to Neutrino Mixing Sum Rules

    Gehrlein, J; Spinrath, M; Titov, A V

    2016-01-01

    Neutrino mixing sum rules are common to a large class of models based on the (discrete) symmetry approach to lepton flavour. In this approach the neutrino mixing matrix $U$ is assumed to have an underlying approximate symmetry form $\\tilde{U}_{\

  4. The case for mixed dark matter from sterile neutrinos

    Lello, Louis

    2015-01-01

    Sterile neutrinos are $SU(2)$ singlets that mix with active neutrinos via a mass matrix, its diagonalization leads to mass eigenstates that couple via standard model vertices. We study the cosmological production of heavy neutrinos via \\emph{standard model charged and neutral current vertices} under a minimal set of assumptions: i) the mass basis contains a hierarchy of heavy neutrinos, ii) these have very small mixing angles with the active (flavor) neutrinos, iii) standard model particles, including light (active-like) neutrinos are in thermal equilibrium. If kinematically allowed, the same weak interaction processes that produce active-like neutrinos also produce the heavier species. We introduce the quantum kinetic equations that describe their production, freeze out and decay and discuss the various processes that lead to their production in a wide range of temperatures assessing their feasibility as dark matter candidates. We identify processes in which finite temperature collective excitations may lead...

  5. Neutrino Mixing Angles in Sequential Dominance to NLO and NNLO

    Antusch, S; King, S F

    2010-01-01

    Neutrinos with hierarchical masses and two large mixing angles may naturally originate from sequential dominance (SD). Within this framework we present analytic expressions for the neutrino mixing angles including the next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) corrections arising from the second lightest and lightest neutrino masses. The analytic results for neutrino mixing angles in SD presented here, including the NLO and NNLO corrections, are applicable to a wide class of models and may provide useful insights when confronting the models with data from high precision neutrino experiments. We also point out that for special cases of SD corresponding to form dominance (FD) the NLO and NNLO corrections both vanish. For example we study tri-bimaximal (TB) mixing via constrained sequential dominance (CSD) which involves only a NNLO correction and tri-bimaximal-reactor (TBR) mixing via partially constrained sequential dominance (PCSD) which involves a NLO correction suppressed by the sm...

  6. Review of Neutrino Mixing and Results from Daya Bay

    Experimental observations have established that neutrinos undergo flavor oscillations as they propagate due to quantum mechanical mixing between the mass states and flavor states. The Daya Bay reactor neutrino experiment has observed the disappearance of electron-type antineutrinos from nuclear reactor cores at the Daya Bay nuclear power complex located in China. This observation allowed Daya Bay to make a measurement of the last neutrino mixing angle, which was previously only known to be small in comparison to the other neutrino mixing angles. An overview of the current status of neutrino oscillation measurements will be presented, followed by the most recent results from Daya Bay and prospects for JUNO, a future neutrino experiment in China

  7. Seesaw neutrino masses and mixing with extended democracy

    Joaquim, F R

    2001-01-01

    In the context of a minimal extension of the Standard Model with three extra heavy right-handed neutrinos, we propose a model for neutrino masses and mixing based on the hipothesis of a complete alignment of the lepton mass matrices in flavour space. Considering a uniform quasi-democratic structure for these matrices, we show that, in the presence of a highly hierarchical right-handed neutrino mass spectrum, the effective neutrino mass matrix, obtained through the seesaw mechanism, can reproduce all the solutions of the solar neutrino problem.

  8. Seesaw neutrino masses and mixing with extended democracy

    In the context of a minimal extension of the Standard Model with three extra heavy right-handed neutrinos, we propose a model for neutrino masses and mixing based on the hipothesis of a complete alignment of the lepton mass matrices in flavour space. Considering a uniform quasi-democratic structure for these matrices, we show that, in the presence of a highly hierarchical right-handed neutrino mass spectrum, the effective neutrino mass matrix, obtained through the seesaw mechanism, can reproduce all the solutions of the solar neutrino problem

  9. Leptonic Generation Mixing, Noncommutative Geometry and Solar Neutrino Fluxes

    Häussling, R; Scheck, F

    1998-01-01

    Triangular mass matrices for neutrinos and their charged partners contain full information on neutrino mixing in a most concise form. Although the scheme is general and model independent, triangular matrices are typical for reducible but indecomposable representations of graded Lie algebras which, in turn, are characteristic for the standard model in noncommutative geometry. The mixing matrix responsible for neutrino oscillations is worked out analytically for two and three lepton families. The example of two families fixes the mixing angle to just about what is required by the Mikheyev-Smirnov-Wolfenstein resonance oscillation of solar neutrinos. In the case of three families we classify all physically plausible choices for the neutrino mass matrix and derive interesting bounds on some of the moduli of the mixing matrix.

  10. Limits on sterile neutrino mixing using atmospheric neutrinos in Super-Kamiokande

    collaboration, The Super-Kamiokande; :; Abe, K.; Haga, Y.; Hayato, Y.; Ikeda, M; Iyogi, K.; Kameda, J.; Kishimoto, Y.; Miura, M.; Moriyama, S.; Nakahata, M.(University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan); Nakano, Y.; Nakayama, S.; Sekiya, H.

    2014-01-01

    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 mix...

  11. Particle Physics Seminar: Towards 3+1 Neutrino Mixing

    Geneva University

    2011-01-01

    GENEVA UNIVERSITY Ecole de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92 Wednesday  12 October  2011 PARTICLE PHYSICS SEMINAR at 17.00 hrs – Stückelberg Auditorium “Towards 3+1 Neutrino Mixing” Par Prof. Carlo Giunti, INFN Torino I will review the recent experimental indications in favor of  short-baseline neutrino oscillations. I will discuss their interpretation in the framework of neutrino mixing schemes with one or more sterile neutrinos which have masses around the eV scale. Taking into account also cosmological constraints, I will present arguments in favor of 3+1 neutrino mixing with one sterile neutrino at the eV scale. Information : http://dpnc.unige.ch/seminaire/annonce.html Organizer : G. Pasztor

  12. Lepton mixing and neutrino masses from A5 and CP

    Di Iura, Andrea

    2016-01-01

    Some properties of lepton mixing and neutrino masses can be computed under the assumption of A5 and CP as a symmetry in the leptonic sector. The results show that four mixing patterns accommodate well the oscillation data, i.e. all the mixing angles are in the 3sigma confidence region. We also introduce an explicit realization of this framework in the case of the Weinberg operator where the neutrino mass spectrum can be computed.

  13. The case for mixed dark matter from sterile neutrinos

    Lello, Louis; Boyanovsky, Daniel

    2016-06-01

    Sterile neutrinos are SU(2) singlets that mix with active neutrinos via a mass matrix, its diagonalization leads to mass eigenstates that couple via standard model vertices. We study the cosmological production of heavy neutrinos via standard model charged and neutral current vertices under a minimal set of assumptions: i) the mass basis contains a hierarchy of heavy neutrinos, ii) these have very small mixing angles with the active (flavor) neutrinos, iii) standard model particles, including light (active-like) neutrinos are in thermal equilibrium. If kinematically allowed, the same weak interaction processes that produce active-like neutrinos also produce the heavier species. We introduce the quantum kinetic equations that describe their production, freeze out and decay and discuss the various processes that lead to their production in a wide range of temperatures assessing their feasibility as dark matter candidates. The final distribution function at freeze-out is a mixture of the result of the various production processes. We identify processes in which finite temperature collective excitations may lead to the production of the heavy species. As a specific example, we consider the production of heavy neutrinos in the mass range Mh lesssim 140 MeV from pion decay shortly after the QCD crossover including finite temperature corrections to the pion form factors and mass. We consider the different decay channels that allow for the production of heavy neutrinos showing that their frozen distribution functions exhibit effects from ``kinematic entanglement'' and argue for their viability as mixed dark matter candidates. We discuss abundance, phase space density and stability constraints and argue that heavy neutrinos with lifetime τ> 1/H0 freeze out of local thermal equilibrium, and conjecture that those with lifetimes τ ll 1/H0 may undergo cascade decay into lighter DM candidates and/or inject non-LTE neutrinos into the cosmic neutrino background. We provide a

  14. Seesaw Neutrino Masses with Large Mixings from Dimensional Deconstruction

    Balaji, K R S; Seidl, G

    2003-01-01

    We demonstrate how the dimension-five seesaw operator which generates neutrino masses and mixings can have a dynamical origin in dimensional deconstruction models. Light neutrino masses arise in such a scenario from the seesaw scale which corresponds to the inverse lattice spacing. It is shown that the deconstructing limit naturally prefers maximal leptonic mixing. Higher-order corrections which are allowed by gauge invariance can transform the bi-maximal into a bi-large mixing. These terms may appear to be non-renormalizable at scales smaller than the deconstruction scale. We quantitatively outline all relevant features for a few example field theories which accomodate current neutrino data.

  15. Higgs mass from neutrino-messenger mixing

    Byakti, Pritibhajan; Mummidi, V Suryanarayana; Vempati, Sudhir K

    2016-01-01

    The discovery of the Higgs particle at 125 GeV has put strong constraints on minimal messenger models of gauge mediation, pushing the stop masses into the multi-TeV regime. Extensions of these models with matter-messenger mixing terms have been proposed to generate a large trilinear parameter, $A_t$, relaxing these constraints. The detailed survey of these models \\cite{Byakti:2013ti,Evans:2013kxa} so far considered messenger mixings with only MSSM superfields. In the present work, we extend the survey to MSSM with inverse-seesaw mechanism. The neutrino-sneutrino corrections to the Higgs mass in the inverse seesaw model are not significant in the minimal gauge mediation model, unless one considers messenger-matter interaction terms. We classify all possible models with messenger-matter interactions and perform thorough numerical analysis to find out the promising models. We found that out of the 17 possible models 15 of them can lead to Higgs mass within the observed value without raising the sfermion masses s...

  16. Constraints on neutrino mixing angle theta_13 and Supernova neutrino fluxes from the LSD neutrino signal from SN1987A

    Lychkovskiy, O

    2006-01-01

    Detection of 5 events by the Liquid Scintillation Detector (LSD) on February, 23, 1987 was recently interpreted as a detection of the electron neutrino flux from the first stage of the two-stage Supernova collapse. We show that, if neutrino mass hierarchy is normal, such interpretation excludes values of neutrino mixing angle \\theta_{13} larger than 3\\cdot 10^{-2}, independently of the particular Supernova collapse model. Also constraints on the original fluxes of neutrinos and antineutrinos of different flavours are obtained.

  17. Leptogenesis from Oscillations of Heavy Neutrinos with Large Mixing Angles

    Drewes, Marco; Gueter, Dario; Klaric, Juraj

    2016-01-01

    The extension of the Standard Model by heavy right-handed neutrinos can simultaneously explain the observed neutrino masses via the seesaw mechanism and the baryon asymmetry of the Universe via leptogenesis. If the mass of the heavy neutrinos is below the electroweak scale, they may be found at LHCb, BELLE II, the proposed SHiP experiment or a future high-energy collider. In this mass range, the baryon asymmetry is generated via $CP$-violating oscillations of the heavy neutrinos during their production. We study the generation of the baryon asymmetry of the Universe in this scenario from first principles of non-equilibrium quantum field theory, including spectator processes and feedback effects. We eliminate several uncertainties from previous calculations and find that the baryon asymmetry of the Universe can be explained with larger heavy neutrino mixing angles, increasing the chance for an experimental discovery. For the limiting cases of fast and strongly overdamped oscillations of right-handed neutrinos,...

  18. Nonmaximal neutrino mixing at NOvA from nonstandard interactions

    Liao, Jiajun; Whisnant, Kerry

    2016-01-01

    Muon neutrino disappearance measurements at NOvA suggest that maximal \\theta_{23} is excluded at the 2.5\\sigma CL. This is in mild tension with T2K data which prefer maximal mixing. Considering that NOvA has a much longer baseline than T2K, we point out that the apparent departure from maximal mixing in NOvA may be a consequence of nonstandard neutrino propagation in matter.

  19. The mixing angle as a function of neutrino mass ratio

    Roy, Subhankar

    2016-01-01

    In the quark sector, we experience a correlation between the mixing angles and the mass ratios. A partial realization of the similar tie-up in the neutrino sector helps to constrain the parametrization of masses and mixing, and hints for a predictive framework. We derive five hierarchy dependent textures of neutrino mass matrix with minimum number of parameters ($\\leq\\,4$), following a model-independent strategy.

  20. Neutrinos How Do They Mix and Violate CP?

    Fritzsch, Harald; Fritzsch, Harald; Xing, Zhi-zhong

    2000-01-01

    We discuss a simple model of lepton mixing and CP violation based on the flavor democracy of charge leptons and the mass degeneracy of neutrinos. A nearly bi-maximal flavor mixing pattern, which is favored by current data on atmospheric and solar neutrino oscillations, emerges naturally from this model after explicit symmetry breaking. The rephasing-invariant strength of CP or T violation can be as large as one percent, leading to significant probability asymmetries between \

  1. Radiative generation of neutrino mixing: degenerate masses and threshold corrections

    Degenerate neutrino masses are excluded by experiment. The experimentally measured mass squared differences together with the yet undetermined absolute neutrino mass scale allow for a quasi-degenerate mass spectrum. For the lightest neutrino mass larger than roughly 0.1 eV, we analyse the influence of threshold corrections at the electroweak scale. We show that typical one-loop corrections can generate the observed neutrino mixing as well as the mass differences starting from exactly degenerate masses at the tree-level. Those threshold corrections have to be explicitly flavour violating. Flavour diagonal, non-universal corrections are not sufficient to simultaneously generate the correct mixing and the mass differences. We apply the new insights to an extension of the Minimal Supersymmetric Standard Model with non-minimal flavour violation in the soft breaking terms and discuss the low-energy threshold corrections to the light neutrino mass matrix in that model.

  2. Status of Tri/Bi-Maximal Neutrino Mixing

    Harrison, P F

    2004-01-01

    Tri/bi-maximal mixing (TBM) is a specific lepton mixing ansatz, which describes the trend of the current neutrino oscillation data, in particular the recent SNO and KAMLAND results. The significant feature of TBM in this respect is |U_e2|^2=|U_m2|^2=|U_t2|^2=1/3, and we say that the nu_2 is tri-maximally mixed. We have generalised the TBM ansatz to a generic mixing matrix with the nu_2 trimaximally mixed, whereby the neutrino mass matrix in the lepton flavour basis takes the form of a general S3 group matrix (3 x 3 `magic-square'). In exact TBM the charged-lepton mass matrix in the neutrino mass basis (where the neutrino mass matrix is diagonal) takes the form of a general S3 class operator. The neutrino mass matrix in the flavour basis is a particular S3 group matrix which is also an S1 C S2 C S3 group-chain class operator, whereby the neutrino mass eigenstates are distinguished by their `mutativity' (M_i = +/-1) and `democracy' (D_i = 0,3) which are both good quantum numbers in exact TBM.

  3. A prediction of neutrino mixing matrix with CP violating phase

    The latest experimental progress has established three kinds of neutrino oscillations with three mixing angles measured to rather high precision. There is still one parameter, i.e., the CP violating phase, missing in the neutrino mixing matrix. It is shown that a replay between different parameterizations of the mixing matrix can determine the full neutrino mixing matrix together with the CP violating phase. From the maximal CP violation observed in the original Kobayashi-Maskawa (KM) scheme of quark mixing matrix, we make an Ansatz of maximal CP violation in the neutrino mixing matrix. This leads to the prediction of all nine elements of the neutrino mixing matrix and also a remarkable prediction of the CP violating phase δCK=(85.48-1.80(-4.90)+4.67(+12.87))° within 1σ (3σ) range from available experimental information. We also predict the three angles of the unitarity triangle corresponding to the quark sector for confronting with the CP violation related measurements.

  4. 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

    2014-01-01

    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.

  5. Models of neutrino mass, mixing and CP violation

    King, Stephen F.

    2015-12-01

    In this topical review we argue that neutrino mass and mixing data motivates extending the Standard Model (SM) to include a non-Abelian discrete flavour symmetry in order to accurately predict the large leptonic mixing angles and {C}{P} violation. We begin with an overview of the SM 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 {C}{P} violation, with precise predictions emerging from constrained SD (CSD). We define the flavour problem and discuss progress towards a theory of favour 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 {C}{P} 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 × SU(5) SUSY GUT of flavour, where both models have interesting implications for leptogenesis.

  6. Models of Neutrino Mass, Mixing and CP Violation

    King, Stephen F

    2015-01-01

    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 ...

  7. Search for sterile neutrino mixing in the muon neutrino to tau neutrino appearance channel with the OPERA detector

    Di Crescenzo, A.; OPERA Collaboration

    2016-05-01

    The OPERA experiment observed ν μ → ν τ oscillations in the atmospheric sector. To this purpose the hybrid OPERA detector was exposed to the CERN Neutrinos to Gran Sasso beam from 2008 to 2012, at a distance of 730 km from the neutrino source. Charged-current interactions of ν τ were searched for through the identification of τ lepton decay topologies. The five observed ν τ interactions are consistent with the expected number of events in the standard three neutrino framework. Based on this result, new limits on the mixing parameters of a massive sterile neutrino may be set. Preliminary results of the analysis performed in the 3+1 neutrino framework are here presented.

  8. Geometric relation for neutrino mixing angles and theta(13)

    Lipmanov, E M

    2011-01-01

    Inspired by the recent T2K discovery of a relatively large theta(13) angle in the neutrino mixing matrix we propose here a simple geometric relation between the three usually thought "independent" neutrino mixing angles - solar {\\theta}12, atmospheric {\\theta}23 and reactor {\\theta}13 ones: cos2(2{\\theta}sol) + cos2(2{\\theta}atm) + cos2(2{\\theta}13) = 1. Using the estimations for the two largest neutrino mixing angles from experimental data analyses in the literature, {\\theta}sol{\\cong} ~ 34.4o, {\\theta}atm{\\cong} ~ 42.8o, the reactor neutrino mixing angle is uniquely predicted {\\theta}13 = 10.8o. In case a little changed data, {\\theta}sol{\\cong} = 34o and {\\theta}atm{\\cong} = 43o the result will be {\\theta}13 =11.2o. And so, the {\\theta}13-value is not very sensitive to the accurate magnitudes of the two largest mixing angles. That prediction for the 'small' neutrino mixing angle is compatible with the latest T2K experimental data with best fit values for the reactor angle ({\\theta}13)bf{\\cong}= 9.7o(11o) fo...

  9. An analytical treatment of the neutrino masses and mixings

    Jora, Renata; Shahid, M Naeem

    2013-01-01

    We obtain analytical formulas which connect the neutrino masses and the leptonic mixing matrix with the entries in the mass matrix for the approximation in which the charged lepton mixing matrix is the unit matrix. We also extract the CP violation phase and determine the conditions in which this is present.

  10. Overview of Neutrino Mixing Models and Their Mixing Angle Predictions

    Albright, Carl H.

    2009-01-01

    Comment: 5 pages, 6 figures, written version of talk presented at the 11th International Workshop on Neutrino Factories, Superbeams and Beta Beams, Illinois Institute of Technology, Chicago, July 20-25, 2009; abbreviated version of arXiv:0905.0146 which appeared in Proceedings of the 13th International Workshop on Neutrino Telescopes, Venice, March 10-13, 2009

  11. Sterile neutrinos: direct mixing effects versus induced mass matrix of active neutrinos

    Smirnov, A Yu; Funchal, Renata Zukanovich; Smirnov, Alexei Yu.

    2006-01-01

    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 ...

  12. Implications of neutrino masses and mixing for weak processes

    A general theory is presented of weak processes involving neutrinos which consistently incorporates the possibility of nonzero neutrino masses and associated lepton mixing. The theory leads to new tests for and bounds on such masses and mixing. These tests make use of (π,K)/sub l2/ decay, nuclear β decay, and μ and tau decays, among others. New experiments at SIN and KEK to apply the tests are mentioned. Further, some implications are discussed for (1) the analysis of the spectral parameters in leptonic decays to determine the Lorentz structure of the weak leptonic couplings; (2) fundamental weak interaction constants such as G/sub μ/, G/sub V/', f/sub π/, f/sub K/, V/sub uq/, q = d or s, m/sub W/, and m/sub Z/; and (3) neutrino propagation

  13. Modified Friedberg-Lee symmetry for neutrino mixing

    Zhao, Zhen-hua

    2015-12-01

    In this paper, we put forward a special neutrino mass matrix which is invariant under a modified Friedberg-Lee (FL) transformation νe→νe-2 ξ and νμ ,τ→νμ ,τ+ξ with ξ being a space-time independent element of the Grassmann algebra. Compared to the original FL symmetry (with the transformation νe ,μ ,τ→νe ,μ ,τ+ξ ) which results in the TM2 neutrino mixing, the modified FL symmetry will lead us to the TM1 mixing which has a better agreement with the experimental results. While the original FL symmetry has to be broken in order to produce a realistic neutrino mass spectrum, the modified FL symmetry is allowed to remain intact and give us a vanishing m1. A combination of the FL symmetry with the μ -τ reflection symmetry is also discussed.

  14. Pattern of neutrino mixing in grand unified theories

    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. 1015GeV) but no left-handed Majorana mass, there is small ν/sub e/ mixing but ν/sub μ/ - ν/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, ν/sub e/ - ν/sub μ/ mixing can be of the order of the Cabbibo angle

  15. On self-complementarity relations of neutrino mixing

    With the latest results of a large mixing angle θ13 for neutrinos by the T2K, MINOS and Double Chooz experiments, we find that the self-complementarity (SC) relations agree with the data in some angle-phase parametrizations of the lepton mixing matrix. There are three kinds of self-complementarity relations: (1) θi+θj=θk=45°; (2) θi+θj=θk; (3) θi+θj=45° (where i, j, k denote the mixing angles in the angle-phase parametrizations). We present a detailed study on the self-complementarity relations in nine different angle-phase parametrizations, and also examine the explicit expressions in reparametrization-invariant form, as well as their deviations from global fit. These self-complementarity relations may lead to new perspective on the mixing pattern of neutrinos.

  16. Seesaw neutrino masses with large mixings from dimensional deconstruction

    We demonstrate a dynamical origin for the dimension-five seesaw operator in dimensional deconstruction models. Light neutrino masses arise from the seesaw scale which corresponds to the inverse lattice spacing. It is shown that the deconstructing limit naturally prefers maximal leptonic mixing. Higher-order corrections which are allowed by gauge invariance can transform the bimaximal into a bilarge mixing. These terms may appear to be nonrenormalizable at scales smaller than the deconstruction scale

  17. Neutrino Mixing and Leptogenesis in $\\mu-\\tau$ Symmetry

    Lashin, E I; Hamzaoui, C; Nasri, S

    2014-01-01

    We study the consequences of the $Z_2$-symmetry behind the $\\mu$-$\\tau$ universality in neutrino mass matrix. We then implement this symmetry in the type-I seesaw mechanism and show how it can accommodate all sorts of lepton mass hierarchies and generate enough lepton asymmetry to interpret the observed baryon asymmetry in the universe. We also show how a specific form of a high-scale perturbation is kept when translated via the seesaw into the low scale domain, where it can accommodate the neutrino mixing data. We finally present a realization of the high scale perturbed texture through addition of matter and extra exact symmetries.

  18. Exploring neutrino mixing with low energy superbeams

    We explore as clearly as possible the features of neutrino oscillation which are relevant for measurements of the CP violating Kobayashi-Maskawa phase δ and the sign of Δ m132. We focus on the so called low-energy option and discuss principles for optimizing experimental parameters to measure these two quantities simultaneously. Toward the goal, we first formulate a method for obtaining a bird-eye view of the phenomenon of neutrino oscillation by introducing a new powerful tool called the 'CP trajectory diagram in bi-probability space'. It allows us to represent pictorially the three effects separately in a single diagram; effect from genuine CP violation due to the sin δ term, effect from the CP conserving cos δ term, and the fake CP violating effect due to earth matter. By using the CP trajectory diagram we observe that there is a two-fold ambiguity in the determination of δ which is related with the sign of Δ m132. We then address the question of what are the promising options for conceptual design of experiments at low energies which looks for CP violation and at the same time would resolve the two-fold ambiguity. We point out that a version with distance of about 700 km, with a megaton class water Cherenkov detector gives an optimal design which allows simultaneous determination of δ and the sign of Δ m132 in situ. We also point out that there is a possibility that the similar in situ measurement of both quantities can be done at the Phase II of JHF experiment with much shorter baseline, under the assumption of nature's kind setting of δ to the region of sin δ·Δm132<0. A technique of running at high (∼ 1 GeV) and low (∼ 0.5 GeV) beam energies is proposed as a method for better identification of δ. (author)

  19. Mixing transformations in quantum field theory and neutrino oscillations

    Blasone, M; Vitiello, G

    1996-01-01

    Field mixing transformations are studied in quantum field theory and the generator of the transformations is found to induce an SU(2) coherent structure in the vacuum state, both for bosons and for fermions. The Fock space for mixed fields is unitarily inequivalent to the Fock space of the unmixed fields in the infinite volume limit. We study neutrino mixing and oscillations and find that the oscillation amplitude is depressed by a factor which is momentum and mass dependent. The usual formula is recovered in the relativistic limit. Phenomenological features of the modified oscillation formula are discussed. Finally, preliminary results of the Green's function formalism are presented.

  20. Large Solar Neutrino Mixing in an Extended Zee Model

    Kitabayashi, T; Kitabayashi, Teruyuki; Yasue, Masaki

    2002-01-01

    The Zee model, which employs the standard Higgs scalar ($\\phi$) with its duplicate ($\\phi^\\prime$) and a singly charged scalar ($h^+$), can utilize two global symmetries associated with the conservation of the numbers of $\\phi$ and $\\phi^\\prime$, $N_{\\phi,\\phi^\\prime}$, where $N_\\phi+N_{\\phi^\\prime}$ coincides with the hypercharge while $N_\\phi-N_{\\phi^\\prime}$ ($\\equiv X$) is a new conserved charge, which is identical to $L_e-L_\\mu-L_\\tau$ for the left-handed leptons. Charged leptons turn out to have $e$-$\\mu$ and $e$-$\\tau$ mixing masses, which are found to be crucial for the large solar neutrino mixing. In an extended version of the Zee model with an extra triplet Higgs scalar (s), neutrino oscillations are described by three steps: 1) the maximal atmospheric mixing is induced by democratic mass terms supplied by $s$ with $X$=2 that can initiate the type II seesaw mechanism for the smallness of these masses; 2) the maximal solar neutrino mixing is triggered by the creation of radiative masses by $h^+$ with...

  1. Neutrino Large Mixing in Universal Yukawa Coupling Model with Small Violation

    Teshima, T; Abe, Y

    2002-01-01

    We have analyzed the possibility that the universal Yukawa coupling (democratic mass matrix) with small violations of Dirac and Majorana neutrinos can induce the large mixing of neutrinos through the seesaw mechanism. The possibility can be achieved by the condition that the violation parameters of Majorana neutrinos are sufficiently smaller than the violation parameters of Dirac neutrinos. Allowed regions of the violation parameters producing the observed neutrino mass hierarchy and large neutrino mixing are not so restricted at present in contrast to the violation parameters for quark sector.

  2. Corrections to scaling neutrino mixing: Non-zero θ13,δCP and baryon asymmetry

    Rupam Kalita

    2015-05-01

    Full Text Available We study a very specific type of neutrino mass and mixing structure based on the idea of Strong Scaling Ansatz (SSA where the ratios of neutrino mass matrix elements belonging to two different columns are equal. There are three such possibilities, all of which are disfavored by the latest neutrino oscillation data. We focus on the specific scenario which predicts vanishing reactor mixing angle θ13 and inverted hierarchy with vanishing lightest neutrino mass. Motivated by several recent attempts to explain non-zero θ13 by incorporating corrections to a leading order neutrino mass or mixing matrix giving θ13=0, here we study the origin of non-zero θ13 as well as leptonic Dirac CP phase δCP by incorporating two different corrections to scaling neutrino mass and mixing: one, where type II seesaw acts as a correction to scaling neutrino mass matrix and the other, with charged lepton correction to scaling neutrino mixing. Although scaling neutrino mass matrix originating from type I seesaw predicts inverted hierarchy, the total neutrino mass matrix after type II seesaw correction can give rise to either normal or inverted hierarchy. However, charged lepton corrections do not disturb the inverted hierarchy prediction of scaling neutrino mass matrix. We further discriminate between neutrino hierarchies, different choices of lightest neutrino mass and Dirac CP phase by calculating baryon asymmetry and comparing with the observations made by the Planck experiment.

  3. Neutrino mass and mixing, and non-accelerator experiments

    We review the current status of experimental knowledge about neutrinos derived from kinematic mass measurements, neutrino oscillation searches at reactors and accelerators, solar neutrinos, atmospheric neutrinos, and single and double beta decay. The solar neutrino results yield fairly strong and consistent indication that neutrino oscillations are occurring. Other evidence for new physics is less consistent and convincing

  4. Neutrino Mixing and the Frobenius Group T13

    Hartmann, Christine

    2011-01-01

    We show that the Frobenius group $T_{13} = Z_{13} \\rtimes Z_3$ is a suitable family symmetry group to study neutrino oscillations. Our approach is to catalog all possibilities within an effective field theory approach, assuming only SU(2)xU(1) supplemented by family symmetry. We will use tribimaximal mixing as a guide to place a constraint on the otherwise various possibilities. This leads to an exact fit between the neutrino and charged lepton sector. Such a fit has not been achieved with any other group so far. The results of this paper may then be useful in future studies on the compatibility of this Frobenius group with other models and mechanisms.

  5. Can a "natural" three-generation neutrino mixing scheme satisfy everything?

    Cardall, C Y; Cardall, Christian Y; Fuller, George M

    1996-01-01

    We examine the potential for a ``natural'' three-neutrino mixing scheme to satisfy available data and astrophysical arguments. By ``natural'' we mean no sterile neutrinos, and a neutrino mass hierarchy similar to that of the charged leptons. We seek to satisfy (or solve): 1. Accelerator and reactor neutrino oscillation constraints, including LSND; 2. The atmospheric muon neutrino deficit problem; 3. The solar neutrino problem; 4. Supernova r-process nucleosynthesis in neutrino-heated supernova ejecta; 5. Cold+hot dark matter models. We argue that putative supernova r-process nucleosynthesis bounds on two-neutrino flavor mixing can be applied directly to three-neutrino mixing in the case where one vacuum neutrino mass eigenvalue difference dominates the others. We show that in this ``one mass scale dominance'' limit, a natural three-neutrino oscillation solution meeting all the above constraints exists only if the atmospheric neutrino data {\\em and} the LSND data can be explained with one neutrino mass differe...

  6. Three-Flavor Analysis of Neutrino Mixing with and without Mass Hierarchy

    Minakata, H

    1996-01-01

    I summarize the results of barely model-dependent phenomenological analyses of the structure of the neutrino flavor mixing. The analyses are based on the three-flavor mixing framework without sterile neutrinos and utilize the hints from solar and atmospheric neutrino observations as well as that from mixed dark matter cosmology. It will be demonstrated that the features of the analysis is sharply distinguished by the two cases (I) with and (II) without dark matter mass scale, and by whether one (or two) mass is dominant (OMD) or the three states are almost degenerate (ADN). The global features of the neutrino mixing is illuminated for these different mass patterns.

  7. Neutrino mixing and oscillations in quantum field theory

    Alfinito, E; Iorio, A; Vitiello, G

    1996-01-01

    We show that the generator of field mixing transformations in Quantum Field Theory induces a non trivial structure in the vacuum which turns out to be a coherent state, both for bosons and for fermions, although with a different condensate structure. The Fock space for mixed fields is unitarily inequivalent to the Fock space of the massive (free) fields in the infinite volume limit. As a practical application we study neutrino mixing and oscillations. A new oscillation formula is found where the oscillation amplitude is depressed, with respect to the usual one, by a factor which is momentum and mass dependent. In the relativistic limit, the usual formula is recovered. We finally discuss in some detail phenomenological features of the modified oscillation formula.

  8. Flavor democracy and type-II seesaw realization of bilarge neutrino mixing

    We generalize the democratic neutrino mixing ansatz by incorporating the type-II seesaw mechanism with S(3) flavor symmetry. For only the triplet mass term or only the conventional seesaw term large neutrino mixing can be achieved only by assuming an unnatural suppression of the flavor democracy contribution. We show that bilarge neutrino mixing can naturally appear if the flavor democracy term is strongly suppressed due to significant cancellation between the conventional seesaw and triplet mass terms. Explicit S(3) symmetry breaking yields successful neutrino phenomenology and various testable correlations between the neutrino mass and mixing parameters. Among the results are a normal neutrino mass ordering, 0.005=e3 vertical bar =22θ23>=0.005, positive JCP and moderate cancellation in the effective mass of the neutrinoless double beta decay

  9. Unitarity and the Three Flavour Neutrino Mixing Matrix

    Parke, Stephen [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Ross-Lonergan, Mark [Durham Univ. (United Kingdom)

    2015-08-20

    Unitarity is a fundamental property of any theory required to ensure we work in a theoretically consistent framework. In comparison with the quark sector, experimental tests of unitarity for the 3x3 neutrino mixing matrix are considerably weaker. It must be remembered that the vast majority of our information on the neutrino mixing angles originates from v-e and vμ disappearance experiments, with the assumption of unitarity being invoked to constrain the remaining elements. New physics can invalidate this assumption for the 3x3 subset and thus modify our precision measurements. We also perform a reanalysis to see how global knowledge is altered when one refits oscillation results without assuming unitarity, and present 3σ ranges for allowed UPMNS elements consistent with all observed phenomena. We calculate the bounds on the closure of the six neutrino unitarity triangles, with the closure of the v-e and vμ triangle being constrained to be ≤0.03, while the remaining triangles are significantly less constrained to be ≤ 0.1 - 0.2. Similarly for the row and column normalization, we find their deviation from unity is constrained to be ≤ 0.2 - 0.4, for four out of six such normalizations, while for the vμ and ve row normalization the deviations are constrained to be ≤0.07, all at the 3σCL. Additionally, we emphasize that there is significant room for new low energy physics, especially in the vτ sector which very few current experiments constrain directly.

  10. High scale mixing relations as a natural explanation for large neutrino mixing

    Abbas, Gauhar; Biswas, Aritra; Gupta, Saurabh; Patra, Monalisa; Rajasekaran, G; Srivastava, Rahul

    2015-01-01

    The origin of small mixing among the quarks and a large mixing among the neutrinos has been an open question in particle physics. In order to answer this question, we postulate general relations among the quarks and the leptonic mixing angles at a high scale, which could be the scale of Grand Unified Theories. The central idea of these relations is that the quark and the leptonic mixing angles can be unified at some high scale either due to some quark-lepton symmetry or some other underlying mechanism and as a consequence, the mixing angles of the leptonic sector are proportional to that of the quark sector. We investigate the phenomenology of the possible relations where the leptonic mixing angles are proportional to the quark mixing angles at the unification scale by taking into account the latest experimental constraints from the neutrino sector. These relations are able to explain the pattern of leptonic mixing at the low scale and thereby hint that these relations could be possible signatures of a hidden...

  11. Neutrino mixing and CP violation from Dirac-Majorana mixing

    Harada, Junpei

    2016-01-01

    We consider a minimal condition that predicts the 1-3 lepton mixing angle $\\theta_{13} \\simeq \\theta_{\\rm C}/\\sqrt{2}$ with $\\theta_{\\rm C}$ the Cabibbo angle, and give the improved prediction of $\\theta_{13}$. In the case of normal mass ordering, the theoretical value of $\\theta_{13}$ is predicted as $\\theta_{13}=8.6^\\circ$, which is in good agreement with the current global best fit. In the case of inverted mass ordering, the theoretical value is predicted as $\\theta_{13}=9.7^\\circ$, which is far from the current global best fit. We also study the leptonic CP violation. We show that any values of the leptonic Dirac CP phase $\\delta_{\\rm CP}$ can be obtained by fine tuning. Without fine tuning, $|\\sin\\delta_{\\rm CP}|$ should be very small, typically of ${\\cal O}(\\lambda^2)$ where $\\lambda\\equiv \\sin\\theta_{\\rm C}$. Furthermore, a model-independent measure of CP violation is proposed, which is applicable to any flavor models.

  12. Exponential parameterization of neutrino mixing matrix with account for CP-violation data

    Zhukovsky, K

    2016-01-01

    The exponential parameterization of Pontecorvo-Maki-Nakagawa-Sakata mixing matrix for neutrino is discussed. The exponential form allows easy factorization and separate analysis of the CP-violating and Majorana terms. Based upon the recent experimental data on the neutrino mixing, the values for the exponential parameterization matrix for neutrinos are determined. The matrix entries for the pure rotational part in charge of the mixing without CP-violation are derived. The complementarity hypothesis for quarks and neutrinos is demonstrated. The comparison of the results, based on most recent and on old data is held. The CP-violating parameter value is estimated, based on the so far imprecise experimental indications, regarding CP-violation for neutrinos. The unitarity of the exponential parameterisation and the CP-violating term transform is confirmed. The transform of the neutrino mass state vector by the exponential matrix with account for CP-violation is shown.

  13. Two-texture zeros and near-maximal atmospheric neutrino mixing angle

    S Dev; Radha Raman Gautam; Lal Singh; Manmohan Gupta

    2016-02-01

    We study the implications of a large value of the effective Majorana neutrino mass for a class of two-texture zero neutrino mass matrices in the flavour basis. We find that these textures predict near-maximal atmospheric neutrino mixing angle in the limit of large effective Majorana neutrino mass. We present the symmetry realization of these textures using the discrete cyclic group Z3. It is found that the texture zeros realized in this work remain stable under the renormalization group running of the effective neutrino mass matrix at one-loop level.

  14. Neutrino masses and mixings: Status of known and unknown $3\

    Capozzi, F; Marrone, A; Montanino, D; Palazzo, A

    2016-01-01

    Within the standard 3nu mass-mixing framework, we present an up-to-date global analysis of neutrino oscillation data (as of January 2016), including the latest available results from experiments with atmospheric neutrinos (Super-Kamiokande and IceCube DeepCore), at accelerators (first T2K anti-nu and NOvA nu runs in both appearance and disappearance mode), and at short-baseline reactors (Daya Bay and RENO far/near spectral ratios), as well as a reanalysis of older KamLAND data in the light of the "bump" feature recently observed in reactor spectra. We discuss improved constraints on the five known oscillation parameters (delta m^2, |Delta m^2|, sin^2theta_12, sin^2theta_13, sin^2theta_23), and the status of the three remaining unknown parameters: the mass hierarchy, the theta_23 octant, and the possible CP-violating phase delta. With respect to previous global fits, we find that the reanalysis of KamLAND data induces a slight decrease of both delta m^2 and sin^2theta_12, while the latest accelerator and atmos...

  15. Noncommutative Geometry and the standard model with neutrino mixing

    Connes, A

    2006-01-01

    We show that allowing the metric dimension of a space to be independent of its KO-dimension and turning the finite noncommutative geometry F-- whose product with classical 4-dimensional space-time gives the standard model coupled with gravity--into a space of KO-dimension 6 by changing the grading on the antiparticle sector into its opposite, allows to solve three problems of the previous noncommutative geometry interpretation of the standard model of particle physics: The finite geometry F is no longer put in "by hand" but a conceptual understanding of its structure and a classification of its metrics is given. The fermion doubling problem in the fermionic part of the action is resolved. The spectral action of our joint work with Chamseddine now automatically generates the full standard model coupled with gravity with neutrino mixing and see-saw mechanism for neutrino masses. The predictions of the Weinberg angle and the Higgs scattering parameter at unification scale are the same as in our joint work but we...

  16. Neutrino Mixing With Non-Zero $\\theta_{13}$ In Zee-Babu Model

    Long, H N

    2014-01-01

    The exact solution for the neutrino mass matrix of the Zee-Babu model is derived. Tribimaximal mixing imposes conditions on the Yukawa couplings, from which the normal mass hierarchy is preferred. The derived conditions give a possibility of Majorana maximal $\\mathrm{CP}$ violation in the neutrino sector. We have shown that non-zero $\\theta_{13}$ is generated if Yukawa couplings between leptons almost equal to each other. The model gives some regions of the parameters where neutrino mixing angles and the normal neutrino mass hierarchy obtained consistent with the recent experimental data.

  17. Neutrino mixing with nonzero θ13 in Zee-Babu model

    Long, Hoang Ngoc; Vien, Vo Van

    2014-05-01

    The exact solution for the neutrino mass matrix of the Zee-Babu model is derived. Tribimaximal mixing imposes conditions on the Yukawa couplings, from which the normal mass hierarchy is preferred. The derived conditions give a possibility of Majorana maximal CP violation in the neutrino sector. We have shown that nonzero θ13 is generated if Yukawa couplings between leptons almost equal to each other. The model gives some regions of the parameters where neutrino mixing angles and the normal neutrino mass hierarchy obtained are consistent with the recent experimental data.

  18. Towards neutrino transport with flavor mixing in supernovae: the Liouville operator

    Cardall, Christian Y

    2009-01-01

    The calculation of neutrino decoupling from nuclear matter requires a transport formalism capable of handling both collisions and flavor mixing. The first steps towards such a formalism are the construction of neutrino and antineutrino "distribution matrices," and a determination of the Liouville equations they satisfy in the noninteracting case. These steps are accomplished through study of a Wigner-transformed "density function," the mean value of paired neutrino quantum field operators.

  19. The see-saw mechanism: Neutrino mixing, leptogenesis and lepton flavour violation

    Werner Rodejohann

    2009-01-01

    The see-saw mechanism to generate small neutrino masses is reviewed. After summarizing our current knowledge about the low energy neutrino mass matrix, we consider reconstructing the see-saw mechanism. Indirect tests of see-saw are leptogenesis and lepton flavour violation in supersymmetric scenarios, which together with neutrino mass and mixing define the framework of see-saw phenomenology. Several examples are given, both phenomenological and GUT-related.

  20. Unifying leptogenesis, dark matter and high-energy neutrinos with right-handed neutrino mixing via Higgs portal

    Di Bari, Pasquale; Palomares-Ruiz, Sergio

    2016-01-01

    We revisit a model in which neutrino masses and mixing are described by a two right-handed (RH) neutrino seesaw scenario, implying a strictly hierarchical light neutrino spectrum. A third decoupled RH neutrino, $N_{\\rm DM}$ with mass $M_{\\rm DM}$, plays the role of cold dark matter (DM) and is produced by the mixing with a source RH neutrino, $N_{\\rm S}$ with mass $M_{\\rm S}$, induced by Higgs portal interactions. The same interactions are also responsible for $N_{\\rm DM}$ decays. We discuss in detail the constraints coming from DM abundance and stability conditions, showing that in the hierarchical case ($M_{\\rm DM} \\gg M_{\\rm S}$) there is an allowed window on $M_{\\rm DM}$, which necessarily implies a contribution from DM decays to the high-energy neutrino flux recently detected by IceCube. We also show how the model can explain the matter-antimatter asymmetry of the Universe via leptogenesis in the quasi-degenerate limit. In this case, the DM mass should be within the range 300 GeV $\\lesssim M_{\\rm S} <...

  1. An $S_4$ model inspired from self-complementary neutrino mixing

    Zhang, Xinyi

    2015-01-01

    We build an $S_4$ model for neutrino masses and mixing based on the self-complementary (SC) neutrino mixing pattern. The SC mixing is constructed from the self-complementarity relation and a maximal CP violation ansatz (with a minus sign), and is realized perturbatively in this model. The model gives predictions on the observables that are compatible with their $3\\sigma$ range, and gives predictions for the not-yet observed quantities like the lightest neutrino mass $m_1\\in [0.003,0.006]$ eV and the Dirac CP violating phase $\\delta\\in[256.05^\\circ,283.69^\\circ]$.

  2. Robust flavor equalization of cosmic neutrino flux by quasi bi-maximal mixing

    Ahluwalia, D V; Adunas, G Z

    2000-01-01

    The observed L/E flatness of the electron-like event ratio in the Super-Kamiokande atmospheric neutrino data strongly favors a quasi bi-maximal mixing matrix. This situation is here exploited to understand the numerical results of Yasuda on the high energy cosmic neutrino flux. In agreement with the Yasuda result, we analytically show how the quasi bi-maximal neutrino mixing makes the high energy cosmic neutrino flux at the AGN/GRB source, F(nu_e):F(nu_mu):F(nu_tau) approx 1:2:0, oscillates to, F(nu_e):F(nu_\\mu):F(nu_tau)approx 1:1:1. Apart from its independence from the underlying mass-squared differences, we find that this prediction is quite robust in that it is independent of the mixing angle responsible for the resolution of the solar/LSND neutrino anomaly.

  3. Flavor Democracy and Type-II Seesaw Realization of Bilarge Neutrino Mixing

    Rodejohann, W; Rodejohann, Werner; Xing, Zhi-zhong

    2004-01-01

    We generalize the democratic neutrino mixing Ansatz by incorporating the type-II seesaw mechanism with S(3) flavor symmetry. We find that bilarge neutrino mixing can naturally appear if the flavor democracy contribution is strongly suppressed due to significant cancellation between the conventional seesaw and triplet mass terms. Explicit S(3) symmetry breaking yields successful neutrino phenomenology and various testable correlations between the neutrino mass and mixing parameters. Among the results are a normal neutrino mass ordering, $0.005 \\le |U_{e3}| \\le 0.057$, $1 - \\sin^2 2\\theta_{23} \\ge 0.005$, positive $J_{\\rm CP}$ and moderate cancellation in the effective mass of the neutrinoless double beta decay.

  4. Oscillation and Mixing Among the Three Neutrino Flavors

    Weiler, Thomas J

    2013-01-01

    With the educated, interested non-specialist as the target audience, we overview what is known and not known about contemporary neutrino physics. Theory tells us that neutrinos are the second-most common particle in the Universe, behind only the quanta of radiation called photons. Almost a trillion neutrinos per second enter each human eyeball, and yet we do not see them; these neutrinos, in roughly equal numbers, are emanations from our Sun and relics of the hot "big bang" era of the early Universe. Much of what we know about neutrinos, and hope to learn in the future, is derived from a unique feature of neutrinos -- "oscillation" among neutrino "flavor" types. An initial neutrino flavor will in general oscillate into another flavor as the neutrino propagates in space and time. Oscillations are a quantum mechanical phenomenon. One of the wonders of neutrinos is that their quantum mechanics may be observed over large distances, even astronomically large. We begin this article with neutrino phenomenology in te...

  5. Neutrino mixing and oscillation in a grand unified field theory SO(10)

    The investigation shows that it is very difficult to achieve neutrino mixing of other than the V/sub μ/-ν/sub tau/ type in any minimal SO(10) model in which neutrino masses are generated by the Gell-Mann-Ramond-Slansky mechanism, because of the severe constraints placed on the mass matrix by quark phenomenology

  6. Search for the sterile neutrino mixing with the ICAL detector at INO

    Behera, S P; Choubey, Sandhya; Datar, V M; Mishra, D K; Mohanty, A K

    2016-01-01

    The study has been carried out on the prospects of probing the sterile neutrino mixing with the magnetized Iron CALorimeter (ICAL) at the India-based Neutrino Observatory (INO), using atmospheric neutrinos as a source. The so-called 3~$+$~1 scenario is considered for active-sterile neutrino mixing and lead to projected exclusion curves in the sterile neutrino mass and mixing angle plane. The analysis is performed using the neutrino event generator NUANCE, modified for ICAL, and folded with the detector resolutions obtained by the INO collaboration from a full GEANT4 based detector simulation. A comparison has been made between the results obtained from the analysis considering only the energy and zenith angle of the muon and combined with the hadron energy due to the neutrino induced event. A small improvement has been observed with the addition of the hadron information to the muon. In the analysis we consider neutrinos coming from all zenith angles and the Earth matter effects are also included. The inclusi...

  7. Neutrino masses and mixing within a SU(3) family symmetry model with one or two light sterile neutrinos

    Hernandez-Galeana, Albino

    2013-01-01

    We report a global fit of parameters for fermion masses and mixing, including light sterile neutrinos, within a local vector $SU(3)$ family symmetry model. In this scenario, ordinary heavy fermions, top and bottom quarks and tau lepton, become massive at tree level from {\\bf Dirac See-saw} mechanisms implemented by the introduction of a new set of $SU(2)_L$ weak singlet vector-like fermions, $U,D,E,N$, with $N$ a sterile neutrino. The $N_{L,R}$ sterile neutrinos allow the implementation of a $8\\times 8$ general tree level See-saw Majorana neutrino mass matrix with four massless eigenvalues. Hence, light fermions, including light neutrinos obtain masses from one loop radiative corrections mediated by the massive $SU(3)$ gauge bosons. This BSM model is able to accommodate the known spectrum of quark masses and mixing in a $4\\times 4$ non-unitary $V_{CKM}$ as well as the charged lepton masses. The explored parameter space region provide the vector-like fermion masses: $M_D \\approx 914.365 $GeV, $M_U \\approx 1.5 ...

  8. Charged lepton correction to tribimaximal lepton mixing and its implications to neutrino phenomenology

    Gollu, Srinu; Mohanta, R

    2013-01-01

    The recent results from Daya Bay and RENO reactor neutrino experiments have firmly established that the smallest reactor mixing angle $\\theta_{13}$ is non-vanishing at the $5 \\sigma$ level, with a relatively large value, i.e., $\\theta_{13}\\approx 9^{\\circ}$. Using the fact that the neutrino mixing matrix can be represented as $V_{\\rm PMNS}=U_l^{\\dagger} U_{\

  9. On-shell renormalization of the mixing matrices in Majorana neutrino theories

    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. (orig.)

  10. Neutrino mixing and CP violation phases in Zee-Babu model

    Van Vien, Vo; Thu, Pham Ngoc

    2014-01-01

    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.

  11. Search for possible forms of neutrino mixing matrix U{sub PMNS}

    Nimai Singh, N.

    2014-06-15

    Two popular forms of neutrino mixing matrix U{sub PMNS}, are the Bi-maximal (BM) mixing and Tri-bimaximal (TBM) mixing matrices which are derived from well known underlying symmetry principles. In the present work, we examine their validity after taking appropriate charged lepton corrections. Tri-bimaximal mixing matrix with charged lepton correction, agrees with the present observational data at 1σ level, but the Bi-maximal mixing with charged lepton correction, fails to accommodate the present observational data at 1σ level on neutrino oscillations. This shortcoming is removed in Bi-large (BL) mixing ansatz with appropriate charged lepton correction. We also discuss the Quark–Lepton Complementarity(QLC) relations and other related issues in neutrino physics.

  12. Neutrino mixing: from the broken μ-τ symmetry to the broken Friedberg–Lee symmetry

    I argue that the observed flavor structures of leptons and quarks might imply the existence of certain flavor symmetries. The latter should be a good starting point to build realistic models towards deeper understanding of the fermion mass spectra and flavor mixing patterns. The μ-τ permutation symmetry serves for such an example to interpret the almost maximal atmospheric neutrino mixing angle (θ23 ~ 45°) and the strongly suppressed CHOOZ neutrino mixing angle (θ13 < 10°). In this talk I like to highlight a new kind of flavor symmetry, the Friedberg–Lee symmetry, for the effective Majorana neutrino mass operator. Luo and I have shown that this symmetry can be broken in an oblique way, such that the lightest neutrino remains massless but an experimentally-favored neutrino mixing pattern is achievable. We get a novel prediction for θ13 in the CP-conserving case: sinθ13 = tanθ12|(1 - tanθ23)/(1 + tanθ23)|. Our scenario can simply be generalized to accommodate CP violation and be combined with the seesaw mechanism. Finally I stress the importance of probing possible effects of μ-τ symmetry breaking either in terrestrial neutrino oscillation experiments or with ultrahigh-energy cosmic neutrino telescopes. (author)

  13. Solar neutrino variations: a manifestation of nonzero neutrino mass and magnetic moment, and mixing

    Time variations of solar neutrino flux are investigated for more that two solar cycles (1970-1994). For each solar neutrino run n, the effective Earth's helio-latitude, the effective sunspots number, the effective latitude of sunspots distribution, and the effective surfaces of sunspots are determined. The correlation of solar electron neutrino fluxes with these parameters for different periods of solar activity are considered. It is found that correlation coefficients change the sign in different periods of solar activity. The obtained information indicate that neutrino should have nonzero mass and nonzero magnetic moment

  14. Self-induced neutrino flavor conversion without flavor mixing

    Chakraborty, Sovan; Izaguirre, Ignacio; Raffelt, Georg

    2016-01-01

    Neutrino-neutrino refraction in dense media can cause self-induced flavor conversion triggered by collective run-away modes of the interacting flavor oscillators. The growth rates were usually found to be of order a typical vacuum oscillation frequency $\\Delta m^2/2E$. However, even in the simple case of a $\

  15. Inconsistence of super-luminal Opera neutrino speed with SN1987A neutrinos burst and with flavor neutrino mixing

    Fargion, D

    2011-01-01

    Recent news from Cern Opera experiment seem to hint for a muon neutrino faster than light, maybe tachyon in nature. If all neutrino are just tachyon their arrival (at 17 MeV) will be even much faster than 17 GeV Opera neutrino, nearly 2.5 times faster than c, coming back nearly 100000 years ago. If all the neutrino velocity, independently on their energy, were frozen at a Opera speed 2.5 10^{-5} times faster than c, than Supernova 1987A had not to be observed (as it is well known to be) on February 23th 1987, but just 4.2 years before. Possibly in late 1982 early 1983, miraculously hidden in oldest IMB records. In such tuned new physics no explanation will be on the same neutrino burst found on February 23 1987. A more consistent scenario is the one where electron neutrinos (and antineutrino) fly at velocity c, while muon neutrino are super-luminal: than SN1987A electron neutrino may be in agreement with observed signals; nevertheless even in this ideal scenario one should also find a coexisting precursor neu...

  16. Progress on the neutrino mixing angle, theta_13

    Karlen, D

    2011-01-01

    Until recently, measurements of theta_13, which describes the nu_e component in the nu_3 mass eigenstate, gave only upper limits, leaving open the possibility that it is zero and eliminating a source of CP violation in the neutrino sector. This year has seen significant advances in measuring theta_13 as precision reactor experiments move from construction phase to physics operation and accelerator experiments give first indications that theta_13 differs from zero. In the years to come, the results from these and other experiments will stringently test the PMNS framework for neutrino oscillation and will start to give information about neutrino CP violation and the neutrino mass hierarchy. This paper summarizes the situation for measuring theta_13 at this pivotal time in neutrino research.

  17. Bilarge neutrino mixing and μ-τ permutation symmetry for two-loop radiative mechanism

    The presence of approximate electron number conservation and μ-τ permutation symmetry of S2 is shown to naturally provide bilarge neutrino mixing. First, the bimaximal neutrino mixing together with Ue3=0 is guaranteed to appear owing to S2, and then, the bilarge neutrino mixing together with |Ue3|2. The observed mass hierarchy of Δm·2 atm2 is subject to another tiny violation of the electron number conservation. This scenario is realized in a specific model based on SU(3)LxU(1)N with two-loop radiative mechanism for neutrino masses. The radiative effects from heavy leptons contained in lepton triplets generate the bimaximal structure, and those from charged leptons, which break S2, generate the bilarge structure together with vertical bar Ue3 vertical bar 2 symmetry is extended to a discrete Z8 symmetry, which also ensures the absence of a one-loop radiative mechanism

  18. What can we learn from high precision measurements of neutrino mixing angles?

    R N Mohapatra

    2004-12-01

    Many experiments are being planned to measure the neutrino mixing angles more precisely. In this note, the theoretical significance of a high precision measurement of these parameters is discussed. It is emphasized that they can provide crucial information about different ways to understand the origin of large atmospheric neutrino mixing and move us closer towards determining the neutrino mass matrix. They may also be able to throw light on the question of lepton–quark unification as well as the existence of any leptonic symmetries. For instance if exact ↔ symmetry in the neutrino mass matrix is assumed to be the reason for maximal - mixing, one gets 13 = 0 and 13 ≃ $\\sqrt{ m^{2}_{\\odot} / m^{2}_{{\\text{A}}}$ or 13 ≃ $ m^{2}_{\\odot} / m^{2}_{{\\text{A}}}$ can provide information about the way the ↔ symmetry breaking manifests in the case of normal hierarchy.

  19. Neutrino masses, lepton flavor mixing and leptogenesis in the minimal seesaw model

    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 μ→e+γ, are also discussed in the supersymmetric extension of the MSM. (author)

  20. Neutrinos

    de Gouvea, A; Scholberg, K; Zeller, G P; Alonso, J; Bernstein, A; Bishai, M; Elliott, S; Heeger, K; Hoffman, K; Huber, P; Kaufman, L J; Kayser, B; Link, J; Lunardini, C; Monreal, B; Morfin, J G; Robertson, H; Tayloe, R; Tolich, N; Abazajian, K; Akiri, T; Albright, C; Asaadi, J; Babu, K S; Balantekin, A B; Barbeau, P; Bass, M; Blake, A; Blondel, A; Blucher, E; Bowden, N; Brice, S J; Bross, A; Carls, B; Cavanna, F; Choudhary, B; Coloma, P; Connolly, A; Conrad, J; Convery, M; Cooper, R L; Cowen, D; da Motta, H; de Young, T; Di Lodovico, F; Diwan, M; Djurcic, Z; Dracos, M; Dodelson, S; Efremenko, Y; Ekelof, T; Feng, J L; Fleming, B; Formaggio, J; Friedland, A; Fuller, G; Gallagher, H; Geer, S; Gilchriese, M; Goodman, M; Grant, D; Gratta, G; Hall, C; Halzen, F; Harris, D; Heffner, M; Henning, R; Hewett, J L; Hill, R; Himmel, A; Horton-Smith, G; Karle, A; Katori, T; Kearns, E; Kettell, S; Klein, J; Kim, Y; Kim, Y K; Kolomensky, Yu; Kordosky, M; Kudenko, Yu; Kudryavtsev, V A; Lande, K; Lang, K; Lanza, R; Lau, K; Lee, H; Li, Z; Littlejohn, B R; Lin, C J; Liu, D; Liu, H; Long, K; Louis, W; Luk, K B; Marciano, W; Mariani, C; Marshak, M; Mauger, C; McDonald, K T; McFarland, K; McKeown, R; Messier, M; Mishra, S R; Mosel, U; Mumm, P; Nakaya, T; Nelson, J K; Nygren, D; Gann, G D Orebi; Osta, J; Palamara, O; Paley, J; Papadimitriou, V; Parke, S; Parsa, Z; Patterson, R; Piepke, A; Plunkett, R; Poon, A; Qian, X; Raaf, J; Rameika, R; Ramsey-Musolf, M; Rebel, B; Roser, R; Rosner, J; Rott, C; Rybka, G; Sahoo, H; Sangiorgio, S; Schmitz, D; Shrock, R; Shaevitz, M; Smith, N; Smy, M; Sobel, H; Sorensen, P; Sousa, A; Spitz, J; Strauss, T; Svoboda, R; Tanaka, H A; Thomas, J; Tian, X; Tschirhart, R; Tully, C; Van Bibber, K; Van de Water, R G; Vahle, P; Vogel, P; Walter, C W; Wark, D; Wascko, M; Webber, D; Weerts, H; White, C; White, H; Whitehead, L; Wilson, R J; Winslow, L; Wongjirad, T; Worcester, E; Yokoyama, M; Yoo, J; Zimmerman, E D

    2013-01-01

    This document represents the response of the Intensity Frontier Neutrino Working Group to the Snowmass charge. We summarize the current status of neutrino physics and identify many exciting future opportunities for studying the properties of neutrinos and for addressing important physics and astrophysics questions with neutrinos.

  1. Precise measurement of the neutrino mixing parameter θ23 from muon neutrino disappearance in an off-axis beam.

    Abe, K; Adam, J; Aihara, H; Akiri, T; Andreopoulos, C; Aoki, S; Ariga, A; Ariga, T; Assylbekov, S; Autiero, D; Barbi, M; Barker, G J; Barr, G; Bass, M; Batkiewicz, M; Bay, F; Bentham, S W; Berardi, V; Berger, B E; Berkman, S; Bertram, I; 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; Caravaca Rodríguez, J; 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; Di Lodovico, F; Di Luise, S; Drapier, O; Duboyski, T; Duffy, K; Dufour, F; Dumarchez, J; Dytman, S; Dziewiecki, M; Emery, S; Ereditato, A; Escudero, L; Finch, A J; Floetotto, L; 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; Ives, S J; Iwai, E; Iyogi, K; Izmaylov, A; Jacob, A; Jamieson, B; Johnson, R A; 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; Kearns, E; Khabibullin, M; Khotjantsev, A; Kielczewska, D; Kikawa, T; Kilinski, A; Kim, J; Kisiel, J; Kitching, P; Kobayashi, T; Koch, L; Kolaceke, A; Konaka, A; Kormos, L L; Korzenev, A; Koseki, K; Koshio, Y; Kreslo, I; Kropp, W; Kubo, H; Kudenko, Y; Kumaratunga, S; Kurjata, R; Kutter, T; Lagoda, J; Laihem, K; Lamont, I; Laveder, M; Lawe, M; Lazos, M; Lee, K P; Lindner, T; Lister, C; Litchfield, R P; Longhin, A; Ludovici, L; Macaire, M; Magaletti, L; Mahn, K; Malek, M; Manly, S; Marino, A D; Marteau, J; Martin, J F; Maruyama, T; Marzec, J; Mathie, E L; Matveev, V; Mavrokoridis, K; Mazzucato, E; McCarthy, M; McCauley, N; McFarland, K S; McGrew, C; Metelko, C; Mezzetto, M; Mijakowski, P; Miller, C A; Minamino, A; Mineev, O; Mine, S; Missert, A; Miura, M; Monfregola, L; Moriyama, S; Mueller, Th A; Murakami, A; Murdoch, M; Murphy, S; Myslik, J; Nagasaki, T; Nakadaira, T; Nakahata, M; Nakai, T; Nakamura, K; Nakayama, S; Nakaya, T; Nakayoshi, K; Naples, D; Nielsen, C; Nirkko, M; Nishikawa, K; Nishimura, Y; O'Keeffe, H M; Ohta, R; Okumura, K; Okusawa, T; Oryszczak, W; Oser, S M; Owen, R A; Oyama, Y; Palladino, V; Palomino, J; Paolone, V; Payne, D; Perevozchikov, O; Perkin, J D; Petrov, Y; Pickard, L; Pinzon Guerra, E S; Pistillo, C; Plonski, P; Poplawska, E; Popov, B; Posiadala, 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; Retiere, F; Robert, A; Rodrigues, P A; Rojas, P; Rondio, E; Roth, S; Rubbia, A; Ruterbories, D; Sacco, R; Sakashita, K; Sánchez, F; Sato, F; Scantamburlo, E; Scholberg, K; Schoppmann, S; Schwehr, J; Scott, M; Seiya, Y; Sekiguchi, T; Sekiya, H; Sgalaberna, D; Shiozawa, M; Short, S; Shustrov, Y; Sinclair, P; Smith, B; Smith, R J; 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; Szeglowski, T; 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; Ueno, K; 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; 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; Żmuda, J

    2014-05-01

    New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter θ23. Using an off-axis neutrino beam with a peak energy of 0.6 GeV and a data set corresponding to 6.57×10(20) protons on target, T2K has fit the energy-dependent νμ oscillation probability to determine oscillation parameters. The 68% confidence limit on sin(2)(θ23) is 0.514(-0.056)(+0.055) (0.511±0.055), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is Δm32(2)=(2.51±0.10)×10(-3)  eV(2)/c(4) (inverted hierarchy: Δm13(2)=(2.48±0.10)×10(-3)  eV(2)/c(4)). Adding a model of multinucleon interactions that affect neutrino energy reconstruction is found to produce only small biases in neutrino oscillation parameter extraction at current levels of statistical uncertainty. PMID:24856687

  2. Precise Measurement of the Neutrino Mixing Parameter \\theta_{23} from Muon Neutrino Disappearance in an Off-axis Beam

    Abe, K; Aihara, H; Akiri, T; Andreopoulos, C; Aoki, S; Ariga, A; Ariga, T; Assylbekov, S; Autiero, D; Barbi, M; Barker, G J; Barr, G; Bass, M; Batkiewicz, M; Bay, F; Bentham, S W; Berardi, V; Berger, B E; Berkman, S; Bertram, I; 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; Caravaca, J; 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, P; De, G; Dealtry, T; Dennis, S R; Densham, C; Di, F; Di, S; Drapier, O; Duboyski, T; Duffy, K; Dufour, F; Dumarchez, J; Dytman, S; Dziewiecki, M; Emery, S; Ereditato, A; Escudero, L; Finch, A J; Floetotto, L; 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; Ives, S J; Iwai, E; Iyogi, K; Izmaylov, A; Jacob, A; Jamieson, B; Johnson, R A; 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; Kearns, E; Khabibullin, M; Khotjantsev, A; Kielczewska, D; Kikawa, T; Kilinski, A; Kim, J; Kisiel, J; Kitching, P; Kobayashi, T; Koch, L; Kolaceke, A; Konaka, A; Kormos, L L; Korzenev, A; Koseki, K; Koshio, Y; Kreslo, I; Kropp, W; Kubo, H; Kudenko, Y; Kumaratunga, S; Kurjata, R; Kutter, T; Lagoda, J; Laihem, K; Lamont, I; Laveder, M; Lawe, M; Lazos, M; Lee, K P; Lindner, T; Lister, C; Litchfield, R P; Longhin, A; Ludovici, L; Macaire, M; Magaletti, L; Mahn, K; Malek, M; Manly, S; Marino, A D; Marteau, J; Martin, J F; Maruyama, T; Marzec, J; Mathie, E L; Matveev, V; Mavrokoridis, K; Mazzucato, E; McCarthy, M; McCauley, N; McFarland, K S; McGrew, C; Metelko, C; Mezzetto, M; Mijakowski, P; Miller, C A; Minamino, A; Mineev, O; Mine, S; Missert, A; Miura, M; Monfregola, L; Moriyama, S; Mueller, Th A; Murakami, A; Murdoch, M; Murphy, S; Myslik, J; Nagasaki, T; Nakadaira, T; Nakahata, M; Nakai, T; Nakamura, K; Nakayama, S; Nakaya, T; Nakayoshi, K; Naples, D; Nielsen, C; Nirkko, M; Nishikawa, K; Nishimura, Y; O'Keeffe, H M; Ohta, R; Okumura, K; Okusawa, T; Oryszczak, W; Oser, S M; Owen, R A; Oyama, Y; Palladino, V; Paolone, V; Payne, D; Perevozchikov, O; Perkin, J D; Petrov, Y; Pickard, L; Pinzon, E S; Pistillo, C; Plonski, P; Poplawska, E; Popov, B; Posiadala, 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; Retiere, F; Robert, A; Rodrigues, P A; Rojas, P; Rondio, E; Roth, S; Rubbia, A; Ruterbories, D; Sacco, R; Sakashita, K; Sánchez, F; Sato, F; Scantamburlo, E; Scholberg, K; Schoppmann, S; Schwehr, J; Scott, M; Seiya, Y; Sekiguchi, T; Sekiya, H; Sgalaberna, D; Shiozawa, M; Short, S; Shustrov, Y; Sinclair, P; Smith, B; Smith, R J; 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; Szeglowski, T; 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; Ueno, K; 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; 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

    2014-01-01

    New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter theta_{23}. Using an off-axis neutrino beam with a peak energy of 0.6 GeV and a data set corresponding to 6.57 x 10^{20} protons on target, T2K has fit the energy-dependent nu_mu oscillation probability to determine oscillation parameters. Marginalizing over the values of other oscillation parameters yields sin^2 (theta_{23}) = 0.514 +0.055/-0.056 (0.511 +- 0.055), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is Delta m^2_{32} = 2.51 +- 0.10 x 10^{-3} eV^2/c^4 (inverted hierarchy: Delta m^2_{13} = 2.48 +- 0.10 x 10^{-3} eV^2/c^4). Adding a model of multinucleon interactions that affect neutrino energy reconstruction is found to produce only small biases in neutrino oscillation parameter extraction at current levels of statistical uncertainty.

  3. On neutrino-mixing-generated lepton asymmetry and the primordial helium-4 abundance

    In this article we discuss lepton asymmetry effect on BBN with neutrino oscillations. We argue that asymmetry much smaller than 0.01, although not big enough to influence directly the nucleosynthesis kinetics, can effect considerably BBN indirectly via neutrino oscillations. Namely, it distorts neutrino spectrum and changes neutrino density evolution and the pattern of oscillations (either suppressing or enhancing them), which in turn effect the primordial synthesis of elements. We show that the results of the paper X. Shi et al., Phys. Rev. D 60, 063002 (1999), based on the assumption that only L > 0.01 will influence helium-4 production, are not valid. Instead, the precise constraints on neutrino mixing parameters from BBN are presented. (author)

  4. Neutrino masses and mixing with seesaw mechanism and universal breaking of extended democracy

    Akhmedov, E K; Joaquim, F R; Silva-Marcos, Joaquim I

    2001-01-01

    In the framework of a minimal extension of the SM, where the only additional fields are three right-handed neutrinos, we suggest that the charged lepton, the Dirac neutrino and the right-handed Majorana neutrino mass matrices are all, to leading approximation, proportional to the democratic matrix. With the further assumption that the breaking of this extended democracy is universal for all leptonic mass matrices, a large mixing in the 2-3 sector can be obtained and is linked to the seesaw mechanism, together with the existence of a strong hierarchy in the masses of right-handed neutrinos. A good fit to all solar and atmospheric neutrino data is obtained.

  5. Bounds on sterile neutrino mixing for cosmologically interesting mass range

    Nunokawa, H; Rossi, A; Valle, José W F

    1999-01-01

    This talk summarizes our recent work which studied the impact of resonant neutrino) conversions on supernova physics, under the assumption that the mass of the sterile state is in the few eV -cosmologically significant range.

  6. Reactor anti-neutrinos: measurement of the θ13 leptonic mixing angle and search for potential sterile neutrinos

    The Double Chooz experiment aims to measure the θ13 mixing angle through the disappearance -induced by the oscillation phenomenon - of anti-neutrinos produced by the Chooz nuclear reactors. In order to reduce systematic uncertainties, the experiment relies on the relative comparison of detected signals in two identical liquid scintillator detectors. The near one, giving the normalization of the emitted flux, is currently being built and will be delivered in spring 2014. The far detector, sensitive to θ13, is located at about one kilometer and is taking data since 2011. In this first phase of the experiment, the far detector data are compared to a prediction of the emitted neutrino flux to estimate θ13. In this thesis, the Double Chooz experiment and its analysis are presented, especially the background studies and the rejection of parasitic signals due to light emitted by photo-multipliers. Neutron fluxes between the different detector volumes impact the definition of the fiducial volume of neutrino interactions and the efficiency of detection. Detailed studies of these effects are presented. As part of the Double Chooz experiment, studies were performed to improve the prediction of neutrino flux emitted by reactors. This work revealed a deficit of observed neutrino rates in the short baseline experiments of last decades. This deficit could be explained by an oscillation to a sterile state. The Stereo project aims to observe a typical signature of oscillations: the distortion of neutrino spectra both in energy and baseline. This thesis presents the detector concept and simulations as well as sensitivity studies. Background sources and the foreseen shielding are also discussed. (author)

  7. Mixed cold-hot dark matter model with several massive neutrino types

    Pogosyan, D; Pogosyan, Dmitri; Starobinsky, Alexei

    1995-01-01

    Mixed cold-hot dark matter cosmological models (CHDM) with \\Omega_{tot}=1, approximately flat initial spectrum of adiabatic perturbations and 1, 2 or 3 types of massive neutrinos are compared and tested using recent observational data. The models with 2 or 3 neutrino types of equal mass permit as the best fit larger values of both the Hubble constant (H_0\\le 60 for 2 types, H_0\\le 65 for 3 types) and the total \\Omega_{\

  8. A further study of the Frampton-Glashow-Yanagida model for neutrino masses, flavor mixing and baryon number asymmetry

    Zhang, Jue; Zhou, Shun

    2015-01-01

    In light of the latest neutrino oscillation data, we revisit the minimal scenario of type-I seesaw model, in which only two heavy right-handed Majorana neutrinos are introduced to account for both tiny neutrino masses and the baryon number asymmetry in our Universe. In this framework, we carry out a systematic study of the Frampton-Glashow-Yanagida ansatz by taking into account the renormalization-group running of neutrino mixing parameters and the flavor effects in leptogenesis. We demonstra...

  9. Bi-large Neutrino Mixing See-Saw Mass Matrix with Texture Zeros and Leptogenesis

    CHAO Wei; HE Xiao-Gang; LI Xue-Qian

    2006-01-01

    We study constraints on neutrino properties for a class of bi-large mixing See-Saw mass matrices with texture zeros and with the related Dirac neutrino mass matrix to be proportional to a diagonal matrix of the form diag(e, 1, 1). Texture zeros may occur in the light (class a)) or in the heavy (class b)) neutrino mass matrices. Each of these two classes has 5 different forms which can produce non-trivial three generation mixing with at least one texture zero. We find that two types of texture zero mass matrices in both class a and class b can be consistent with present data on neutrino masses and mixing. None of the neutrinos can have zero masses and the lightest of the light neutrinos has a mass larger than about 0.046 eV for class a and 0.0027 eV for class b. In these models although the CKM CP violating phase vanishes, the non-zero Majorana phases can exist and can play an important role in producing the observed baryon asymmetry in our universe through leptogenesis mechanism. The requirement of producing the observed baryon asymmetry can further distinguish different models and also restrict the See-Saw scale to be in the range of 1012 ~ 1015GeV. We also discuss RG effects on V13.

  10. A massless neutrino and lepton mixing patterns from finite discrete subgroups of U(3)

    Finite discrete subgroups of U(3) as possible flavour symmetries Gf for a massless neutrino with predictive mixing angles are studied. This is done by assuming that a residual symmetry Sν appropriate for describing a massless neutrino is contained in Gf. It is shown that all the groups Gf admitting three dimensional faithful irreducible representation and generated from a specific set of 3×3 matrices imply only one of the three flavour compositions for the massless state namely, unmixed, maximally mixed with equal probabilities and bimaximally mixed with probabilities (0,1/2,1/2) and their permutations. This result holds irrespective of the order of Gf and the choice of Sν within it. All of these lead to unfavorable leading order prediction for the solar mixing angle. Neutrino mixing pattern is then numerically investigated in case of subgroups of U(3) with order less than 512 and it is found that only one of these can lead to a massless neutrino and leading order predictions for all the mixing angles close to their experimental values. Ways to correct for the solar angle prediction are proposed and two concrete examples giving the observed mixing pattern are discussed

  11. Neutrino oscillations

    Lecture notes on neutrino oscillations are given, including some background about neutrino mixing and masses, descriptions of flavour oscillations and experimental attempts to detect them, matter effects and neutrino-antineutrino oscillations. (U.K.)

  12. The strongest bounds on active-sterile neutrino mixing after Planck data

    Light sterile neutrinos can be excited by oscillations with active neutrinos in the early universe. Their properties can be constrained by their contribution as extra-radiation, parameterized in terms of the effective number of neutrino species Neff, and to the universe energy density today Ωνh2. Both these parameters have been measured to quite a good precision by the Planck satellite experiment. We use this result to update the bounds on the parameter space of (3+1) sterile neutrino scenarios, with an active-sterile neutrino mass squared splitting in the range (10−5–102) eV2. We consider both normal and inverted mass orderings for the active and sterile states. For the first time we take into account the possibility of two non-vanishing active-sterile mixing angles. We find that the bounds are more stringent than those obtained in laboratory experiments. This leads to a strong tension with the short-baseline hints of light sterile neutrinos. In order to relieve this disagreement, modifications of the standard cosmological scenario, e.g. large primordial neutrino asymmetries, are required

  13. The strongest bounds on active-sterile neutrino mixing after Planck data

    Mirizzi, Alessandro [II Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Mangano, Gianpiero [Istituto Nazionale di Fisica Nucleare – Sezione di Napoli, Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Saviano, Ninetta, E-mail: ninetta.saviano@desy.de [II Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Istituto Nazionale di Fisica Nucleare – Sezione di Napoli, Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Dipartimento di Fisica, Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Borriello, Enrico [II Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Giunti, Carlo [Department of Physics, University of Torino and INFN, Via P. Giuria 1, I-10125 Torino (Italy); Miele, Gennaro; Pisanti, Ofelia [Istituto Nazionale di Fisica Nucleare – Sezione di Napoli, Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Dipartimento di Fisica, Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy)

    2013-10-07

    Light sterile neutrinos can be excited by oscillations with active neutrinos in the early universe. Their properties can be constrained by their contribution as extra-radiation, parameterized in terms of the effective number of neutrino species N{sub eff}, and to the universe energy density today Ω{sub ν}h{sup 2}. Both these parameters have been measured to quite a good precision by the Planck satellite experiment. We use this result to update the bounds on the parameter space of (3+1) sterile neutrino scenarios, with an active-sterile neutrino mass squared splitting in the range (10{sup −5}–10{sup 2}) eV{sup 2}. We consider both normal and inverted mass orderings for the active and sterile states. For the first time we take into account the possibility of two non-vanishing active-sterile mixing angles. We find that the bounds are more stringent than those obtained in laboratory experiments. This leads to a strong tension with the short-baseline hints of light sterile neutrinos. In order to relieve this disagreement, modifications of the standard cosmological scenario, e.g. large primordial neutrino asymmetries, are required.

  14. Quantum effects for the neutrino mixing matrix in the democratic-type model

    Miura, T; Yoshimura, M; Miura, Takahiro; Takasugi, Eiichi; Yoshimura, Masaki

    2000-01-01

    We investigate the quantum effects for the democratic-type neutrino mass matrix given at the right-handed neutrino mass scale $m_R$ in order to see (i) whether $\\theta_{23}=-\\pi/4$ predicted by the model is stable to explain the atmospheric neutrino anomaly, (ii) how $\\theta_{12}$ and $\\theta_{13}$ behave, and (iii) whether the predicted Dirac CP phase $\\delta$ keeps maximal size, at the weak scale $m_Z$. We find that, for the (inversely) hierarchical mass spectrum with $m_1\\sim m_2$, $\\theta_{23}$ and $\\theta_{13}$ are stable, while $\\theta_{12}$ is not so, which leads to the possibility that the solar neutrino mixing angle can become small at $m_Z$ even if it is taken large at $m_R$, or vice versa. We also show that $\\delta$ keeps almost maximal for the above mass spectrum, and our model can give the large CP violation effect in the future neutrino oscillation experiments if the solar neutrino puzzle is explained by the large mixing angle MSW solution.

  15. A Mechanism for Ordinary-Sterile Neutrino Mixing

    Langacker, Paul

    1998-01-01

    Efficient oscillations between ordinary (active) and sterile neutrinos can occur only if Dirac and Majorana mass terms exist which are both small and comparable. It is shown that this can occur naturally in a class of string models, in which higher-dimensional operators in the superpotential lead to an intermediate scale expectation value for a scalar field and to suppressed Dirac and Majorana fermion masses.

  16. Higgs portal dark matter and neutrino mass and mixing with a doubly charged scalar

    Hierro, I M; Rigolin, S

    2016-01-01

    We consider an extension of the Standard Model involving two new scalar particles around the TeV scale: a singlet neutral scalar $\\phi$, to be eventually identified as the Dark Matter candidate, plus a doubly charged $SU(2)_L$ singlet scalar, $S^{++}$, that can be the source for the non-vanishing neutrino masses and mixings. Assuming an unbroken $Z_2$ symmetry in the scalar sector, under which only the additional neutral scalar $\\phi$ is odd, we write the most general (renormalizable) scalar potential. The model may be regarded as a possible extension of the conventional Higgs portal Dark Matter scenario which also accounts for neutrino mass and mixing. This framework cannot completely explain the observed positron excess. However a softening of the discrepancy observed in conventional Higgs portal framework can be obtained, especially when the scale of new physics responsible for generating neutrino masses and lepton number violating processes is around 2 TeV.

  17. Quark-lepton complementarity and tribimaximal neutrino mixing from discrete symmetry

    The quark-lepton complementarity (QLC) relations indicate a deep structure that interrelates quarks and leptons. We propose new scenarios, in a seesaw framework with discrete A4 flavor symmetry, which can accommodate the QLC relations and the nonzero neutrino mixing angle θ13 together with all the available neutrino experimental data, in a consistent way to generate the Cabibbo-Kobayashi-Maskawa (CKM) matrix for the quark mixing. Certain effective dimension-5 operators are introduced, which induce a deviation of the lepton mixing matrix from the tribimaximal mixing pattern and lead the quark mixing matrix to the CKM one in form. We explicitly demonstrate three different possibilities of constructing the charged-lepton mixing matrix and point out that the phases of its elements play a crucial role to satisfy the QLC relations. We find that for the reactor mixing angle θ13 its possible values can vary around the center value sinθ13≅λ/√(2) (λ≅0.22 being the Cabbibo angle) and have the lower bound θ13 > or approx. 3.5 deg. We also show that sizable leptonic CP violation characterized by the Jarlskog invariant |JCP|∼O(10-2) is allowed, which is expected to be tested in future experiments such as the upcoming long baseline neutrino oscillation ones.

  18. On quasidegeneracy of Majorana neutrinos and the observed pattern of Leptonic mixing

    Rebelo, M N

    2016-01-01

    We relate the observed pattern of leptonic mixing to the quaidegeneracy of three Majorana neutrinos. We show how lifting the degeneracy may lead to the measured value of $|U_{13}|$ and to sizeable CP violation of Dirac-type. We show some of the correlations obtained among physical observables, starting from some of the most interesting schemes proposed in the literature.

  19. The S{sub 3} flavour symmetry: Neutrino masses and mixings

    Gonzalez Canales, F. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (Mexico); Facultad de Ciencias de la Electronica, Benemerita Universidad Autonoma de Puebla (Mexico); Mondragon, A.; Mondragon, M. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (Mexico)

    2013-04-02

    In this work, we discuss the neutrino masses and mixings as the realization of an S{sub 3} flavour permutational symmetry in two models, namely the Standard Model and an extension of the Standard Model with three Higgs doublets. In the S{sub 3} Standard Model, mass matrices of the same generic form are obtained for the neutrino and charged leptons when the S{sub 3} flavour symmetry is broken sequentially according to the chain S{sub 3L} x S{sub 3R} contains S{sub 3}{sup diag} contains S{sub 2}. In the minimal S{sub 3}-symmetric extension of the Standard Model, the S{sub 3} symmetry is left unbroken, and the concept of flavour is extended to the Higgs sector by introducing in the theory three Higgs fields which are SU(2) doublets. In both models, the mass matrices of the neutrinos and charged leptons are reparametrized in terms of their eigenvalues, and exact, explicit analytical expressions for the neutrino mixing angles as functions of the masses of neutrinos and charged leptons are obtained. In the case of the S{sub 3} Standard Model, from a {chi}{sup 2} fit of the theoretical expressions of the lepton mixing matrix to the values extracted from experiment, the numerical values of the neutrino mixing angles are obtained in excellent agreement with experimental data. In the S{sub 3} extension of the Standard Model, if two of the right handed neutrinos masses are degenerate, the reactor and atmospheric mixing angles are determined by the masses of the charged leptons, yielding {theta}{sub 23} in excellent agreement with experimental data, and {theta}{sub 13} different from zero but very small. If the masses of the three right handed neutrinos are assumed to be different, then it is possible to get {theta}{sub 13}also in very good agreement with experimental data. We also show the branching ratios of some selected flavour changing neutral currents (FCNC) process as well as the contribution of the exchange of a neutral flavour changing scalar to the anomaly of the

  20. Neutrino masses and oscillations

    New effects related to refraction of neutrinos in different media are reviewed and implication of the effects to neutrino mass and mixing are discussed. Patterns of neutrino masses and mixing implied by existing hints/bounds are described. Recent results on neutrino mass generation are presented. They include neutrino masses in SO(10) GUT's and models with anomalous U(1), generation of neutrino mass via neutrino-neutralino mixing, models of sterile neutrino. (author). 95 refs, 9 figs

  1. Numerical consistency check between two approaches to radiative corrections for neutrino masses and mixings

    Mrinal Kumar Das; Mahadev Patgiri; N Nimai Singh

    2005-12-01

    We briefly outline the two popular approaches on radiative corrections to neutrino masses and mixing angles, and then carry out a detailed numerical analysis for a consistency check between them in MSSM. We find that the two approaches are nearly consistent with a discrepancy factor of 4.2% with running vacuum expectation value (VEV) (13% for scale-independent VEV) in mass eigenvalues at low-energy scale but the predictions on mixing angles are almost consistent. We check the stability of the three types of neutrino models, i.e., hierarchical, inverted hierarchical and degenerate models, under radiative corrections, using both approaches, and find consistent conclusions. The neutrino mass models which are found to be stable under radiative corrections in MSSM are the normal hierarchical model and the inverted hierarchical model with opposite CP parity. We also carry out numerical analysis on some important conjectures related to radiative corrections in the MSSM, viz., radiative magnification of solar and atmospheric mixings in the case of nearly degenerate model having same CP parity (MPR conjecture) and radiative generation of solar mass scale in exactly two-fold degenerate model with opposite CP parity and non-zero 3 (JM conjecture). We observe certain exceptions to these conjectures. We find a new result that both solar mass scale and 3 can be generated through radiative corrections at low energy scale. Finally the effect of scale-dependent vacuum expectation value in neutrino mass renormalisation is discussed.

  2. Very Long Baseline Neutrino Oscillation Experiments for Precise Measurements of Mixing Parameters and CP Violating Effects

    Diwan, M V; Gallardo, J; Kahn, S; Kirk, H; Marciano, W; Morse, W; Parsa, Z; Samios, Nicholas P; Semertzidis, Y K; Viren, B M; Weng, W; Yamin, P; Frati, W; Lande, K; Mann, A K; Berg, R V; Wildenhain, P S; Klein, J R; Mocioiu, I; Shrock, R E; McDonald, K T

    2003-01-01

    We analyze the prospects of a feasible, very long baseline neutrino oscillation experiment consisting of a conventional horn produced low energy wide band beam and a detector of 500 kT fiducial mass with modest requirements on event recognition and resolution. Such an experiment is intended primarily to measure CP violating effects in the neutrino sector for 3-generation mixing. We analyze the sensitivity of such an experiment. We conclude that this experiment will allow determination of the CP parameter $\\delta_{CP}$, if the currently unknown mixing parameter $\\sin ^2 2 \\theta_{13} \\geq 0.01$, a value about 10 times lower than the present experimental upper limit. In addition to $\\theta_{13}$ and $\\delta_{CP}$, the experiment has great potential for precise measurements of most other parameters in the neutrino mixing matrix including $\\Delta m^2_{32}$, $\\sin^2 2\\theta_{23}$, $\\Delta m^2_{21}\\times \\sin^2 2 \\theta_{12}$, and the mass ordering of neutrinos through the observation of the matter effect in the $\\...

  3. What can we learn from high precision measurements of neutrino mixing angles?

    Many experiments are being planned to measure the neutrino mixing angles more precisely. In this note, the theoretical significance of a high precision measurement of these parameters is discussed. It is emphasized that they can provide crucial information about different ways to understand the origin of large atmospheric neutrino mixing and move us closer towards determining the neutrino mass matrix. They may also be able to throw light on the question of lepton-quark unification as well as the existence of any leptonic symmetries. For instance if exact μ ↔ τ symmetry in the neutrino mass matrix is assumed to be the reason for maximal νμ → ντ mixing, one gets θ13 = 0 and θ13 ≅ √ Δm20/Δm2A or θ13 ≅ Δm20/Δm2A can provide information about the way the μ ↔ τ symmetry breaking manifests in the case of normal hierarchy. (author)

  4. Doubly perturbed S3 neutrinos and the s13 mixing parameter

    We further study a predictive model for the masses and mixing matrix of three Majorana neutrinos. At zeroth order the model yielded degenerate neutrinos and a generalized tribimaximal mixing matrix. At first order the mass splitting was incorporated and the tribimaximal mixing matrix emerged with very small corrections but with a zero value for the parameter s13. In the present paper a different, assumed weaker, perturbation is included which gives a nonzero value for s13 and further corrections to other quantities. These corrections are worked out and their consequences discussed under the simplifying assumption that the conventional CP violation phase vanishes. It is shown that the existing measurements of the parameter s23 provide strong bounds on s13 in this model.

  5. Doubly perturbed $S_3$ neutrinos and the $s_{13}$ mixing parameter

    Jora, Renata; Shahid, M Naeem

    2010-01-01

    We further study a predictive model for the masses and mixing matrix of three Majorana neutrinos. At zeroth order the model yielded degenerate neutrinos and a generalized ``tribimaximal" mixing matrix. At first order the mass splitting was incorporated and the tribimaximal mixing matrix emerged with very small corrections but with a zero value for the parameter $s_{13}$. In the present paper a different, assumed weaker, perturbation is included which gives a non zero value for $s_{13}$ and further corrections to other quantities. These corrections are worked out and their consequences discussed under the simplifying assumption that the conventional CP violation phase vanishes. It is shown that the existing measurements of the parameter $s_{23}$ provide strong bounds on $s_{13}$ in this model.

  6. Neutrino masses and mixings in a predictive SO(10) model with CKM CP violation

    It has recently been shown that a minimal SO(10) model with a single 10 and a single 126 Higgs field breaking B-L symmetry predicts large solar and atmospheric mixings in agreement with observations if it is assumed that the neutrino mass obeys the type II seesaw formula. No additional symmetries need to be assumed for this purpose. Understanding CP violation in the renormalizable version of the model, however, requires a significant non-CKM source. In this Letter we show that if we extend the model by the inclusion of a heavy 120-dimensional Higgs field, then it can accommodate CKM CP violation while remaining predictive in the neutrino sector. Among the predictions are: (i) solar mixing angle in the observed range; (ii) θ13 in the range of 0.1 to 0.26; (iii) the Dirac phase close to maximal for the central value of the solar mixing angle

  7. Determination of the third neutrino-mixing angle θ13 and its implications

    Roy, D. P.

    2013-05-01

    Until 2010 we had three unknown parameters of neutrino oscillation—the third mixing angle θ13, the sign of the larger mass difference Δm312 and the CP violating phase δ. Thanks to a number of consistent experimental results since then, culminating in the recent Daya Bay reactor neutrino data, we now have a definitive determination of θ13. Moreover its measured value, sin22θ13 ≈ 0.1, is close to its earlier upper limit. This has promising implications for the determination of the two remaining unknown parameters from the present and proposed accelerator neutrino experiments in the foreseeable future. This article presents a pedagogical review of these profound developments for the wider community of young physicists including university students.

  8. Determination of the Third Neutrino-Mixing Angle {\\theta}_(13) and its Implications

    Roy, D P

    2013-01-01

    Till 2010 we had three unknown parameters of neutrino oscillation: the third mixing angle {\\theta}_(13), the sign of the larger mass difference {\\Delta}m^(2)_(31) and the CP violating phase {\\delta}. Thanks to a number of consistent experimental results since then, culminating in the recent Daya Bay reactor neutrino data, we have a definitive determination of {\\theta}_(13) now. Moreover its measured value, sin^(2)_(2 {\\theta}_(13)) = 0.1, is close to its earlier upper limit. This has promising implications for the determination of the two remaining unknown parameters from the present and proposed accelerator neutrino experiments in the foreseeable future. This article presents a pedagogical review of these profound developments for the wider community of young physicists including university students.

  9. Neutrino mixing predictions of a minimal SO(10) model with suppressed proton decay

    During the past year, a minimal renormalizable supersymmetric SO(10) model has been proposed with the following properties: it predicts a naturally stable dark matter and neutrino mixing angles θatm and θ13 while at the same time accommodating Cabibbo-Kobayashi-Maskawa CP violation among quarks with no supersymmetry (SUSY) CP problem. Suppression of proton decay for all allowed values of tanβ strongly restricts the flavor structure of the model making it predictive for other processes as well. We discuss the following predictions of the model in this paper, e.g. down-type quark masses, and neutrino oscillation parameters, Ue3, δMNSP, which will be tested by long baseline experiments such as T2K and subsequent experiments using the neutrino beam from JPARC. We also calculate lepton flavor violation and the lepton asymmetry of the Universe in this model

  10. Lepton family symmetries for neutrino masses and mixing

    Ernest Ma

    2006-11-01

    I review some of the recent progress (up to December 2005) in applying non-Abelian discrete symmetries to the family structure of leptons, with particular emphasis on the tribimaximal mixing ansatz of Harrison, Perkins and Scott.

  11. Implications of Recent Data on Neutrino Mixing and Lepton Flavour Violating Decays for the Zee Model

    He, Xiao-Gang

    2011-01-01

    We study implications of recent data on neutrino mixing from T2K, MINOS, Double Chooz and $\\mu \\to e \\gamma$ from MEG for the Zee model. The simplest version of this model has been shown to be ruled out by experimental data some time ago. The general Zee model is still consistent with recent data. We demonstrate this with a constrained Zee model based on naturalness consideration. In this constrained model, only inverted mass hierarchy for neutrino masses is allowed, and $\\theta_{13}$ must be non-zero in order to have correct ratio for neutrino mass-squared differences and for mixing in solar and atmospherical neutrino oscillations. The best fit value of our model for $\\theta_{13}$ is $8.91\\deg$ from T2K and MINOS data, very close to the central value obtained by Double Chooz experiment. There are solutions with non-zero CP violation with the Jarlskog parameter predicted in the range $\\pm 0.039$, $\\pm 0.044$ and $\\pm 0.048$ respectively for a 1$\\sigma$, 2$\\sigma$ and 3$\\sigma$ ranges of other input parameters...

  12. See-saw neutrino masses and large mixing angles in the vortex background on a sphere

    Frère, Jean-Marie; Ling, Fu-Sin

    2010-01-01

    In the vortex background on a sphere, a single 6-dimensional fermion family gives rise to 3 zero-modes in the 4-dimensional point of view, which may explain the replication of families in the Standard Model. Previously, it had been shown that realistic hierarchical mass and mixing patterns can be reproduced for the quarks and the charged leptons. Here, we show that the addition of a single heavy 6-dimensional field that is gauge singlet, unbound to the vortex, and embedded with a bulk Majorana mass enables to generate 4D Majorana masses for the light neutrinos through the see-saw mechanism. The scheme is very predictive. The hierarchical structure of the fermion zero-modes leads automatically to an inverted pseudo-Dirac mass pattern, and always predicts one maximal angle in the neutrino see-saw matrix. It is possible to obtain a second large mixing angle from either the charged lepton or the neutrino sector, and we demonstrate that this model can fit all observed data in neutrino oscillations experiments. Als...

  13. Neutrino mixing and masses in SO(10) GUTs with hidden sector and flavor symmetries

    Chu, Xiaoyong

    2016-01-01

    We consider the neutrino masses and mixing in the framework of SO(10) GUTs with hidden sector consisting of fermionic and bosonic SO(10) singlets and flavor symmetries. The framework allows to disentangle the CKM physics responsible for the CKM mixing and different mass hierarchies of quarks and leptons and the neutrino new physics which produces smallness of neutrino masses and large lepton mixing. The framework leads naturally to the relation $U_{PMNS} \\sim V_{CKM}^{\\dagger} U_0$, where structure of $U_0$ is determined by the flavor symmetry. The key feature of the framework is that apart from the Dirac mass matrices $m_D$, the portal mass matrix $M_D$ and the mass matrix of singlets $M_S$ are also involved in generation of the lepton mixing. This opens up new possibilities to realize the flavor symmetries and explain the data. Using $A_4 \\times Z_4$ as the flavor group, we systematically explore the flavor structures which can be obtained in this framework depending on field content and symmetry assignment...

  14. The weak mixing angle from low energy neutrino measurements: a global update

    Canas, B C; Miranda, O G; Tortola, M; Valle, J W F

    2016-01-01

    Taking into account recent theoretical and experimental inputs on reactor fluxes we reconsider the determination of the weak mixing angle from low energy experiments. We perform a global analysis to all available neutrino-electron scattering data from reactor antineutrino experiments, obtaining sin^2(theta_W) = 0.252 \\pm 0.030. We discuss the impact of the new theoretical prediction for the neutrino spectrum, the new measurement of the reactor antineutrino spectrum by the Daya Bay collaboration, as well as the effect of radiative corrections. We also reanalyze the measurements of the nu_e-e cross section at accelerator experiments including radiative corrections. By combining reactor and accelerator data we obtain an improved determination for the weak mixing angle, sin^2(theta_W) = 0.254 \\pm 0.024.

  15. Direct and Semi-Direct Approaches to Lepton Mixing with a Massless Neutrino

    King, Stephen F

    2016-01-01

    We discuss the possibility of enforcing a massless Majorana neutrino in the direct and semi-direct approaches to lepton mixing, in which the PMNS matrix is partly predicted by subgroups of a discrete family symmetry, extending previous group searches up to order 1535. We find a phenomenologically viable scheme for the semi-direct approach based on $Q(648)$ which contains $\\Delta(27)$ and the quaternion group as subgroups. This leads to novel predictions for the first column of the PMNS matrix corresponding to a normal neutrino mass hierarchy with $m_1=0$, and sum rules for the mixing angles and phase which are characterised by the solar angle being on the low side $\\theta_{12}\\sim 31^{\\circ}$ and the Dirac (oscillation) CP phase $\\delta$ being either about $\\pm 45^\\circ$ or $\\pm \\pi$.

  16. Direct and semi-direct approaches to lepton mixing with a massless neutrino

    King, Stephen F.; Ludl, Patrick Otto

    2016-06-01

    We discuss the possibility of enforcing a massless Majorana neutrino in the direct and semi-direct approaches to lepton mixing, in which the PMNS matrix is partly predicted by subgroups of a discrete family symmetry, extending previous group searches up to order 1535. We find a phenomenologically viable scheme for the semi-direct approach based on Q(648) which contains Δ(27) and the quaternion group as subgroups. This leads to novel predictions for the first column of the PMNS matrix corresponding to a normal neutrino mass hierarchy with m 1 = 0, and sum rules for the mixing angles and phase which are characterised by the solar angle being on the low side θ 12 ˜ 31° and the Dirac (oscillation) CP phase δ being either about ±45° or ±π.

  17. Constructing the large mixing angle MNS matrix in see-saw models with right-handed neutrino dominance

    King, Stephen F.

    2002-09-01

    Recent SNO results strongly favour the large mixing angle (LMA) MSW solar solution. We argue that there are only two technically natural low energy neutrino mass matrix structures consistent with the LMA MSW solution, corresponding to either a hierarchy or an inverted hierarchy with pseudo-Dirac neutrinos. We construct the MNS matrix to leading order in the small angle θ13 including the neutrino and charged lepton mixing angles and phases, the latter playing a crucial rôle for allowing the inverted hierarchy case to be consistent with the LMA MSW solution. We then consider the see-saw mechanism with right-handed neutrino dominance and show how the successful neutrino mass matrix structures may be constructed with no tuning and with small radiative corrections, leading to a full, partial or inverted neutrino mass hierarchy. In each case we derive approximate analytic relations between the input see-saw parameters and the resulting neutrino masses, mixing angles and phases, which will provide a useful guide for unified model building. For the hierarchical cases the LMA MSW solution gives a soft lower bound |Ue3| gtrsim 0.1, just below the current CHOOZ limit. Both hierarchical and inverted hierarchical cases predict small ββ0ν with |mee| ~ 0.007 eV within the sensitivity of future proposals such as GENIUS. Successful leptogenesis is possible if the dominant right-handed neutrino is the heaviest one, but the leptogenesis phase is unrelated to the MNS phases.

  18. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    Spinella, William M.; Weber, Fridolin; Contrera, Gustavo A.; Orsaria, Milva G.

    2016-03-01

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (lesssim10^9 K) and quark fractions (lesssim 30% , and that contributions due to lattice vibrations are insignificant compared to static-lattice contributions.

  19. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (

  20. A new determination of the electroweak mixing angle from muon-neutrino electron scattering

    In this paper the recent result for the weak mixing angle sin2ΘW, determined in neutrino electron scattering by the CHARM II collaboration at the CERN SPS is reported. From the ratio of νμe to νμe scattering cross sections a value of sin2ΘW = 0.233 ± 0.012(stat) ± 0.008(syst) was determined

  1. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    Spinella, William M. [Computational Science Research Center San Diego State University, San Diego, CA (United States); San Diego State University, Department of Physics, San Diego, CA (United States); Weber, Fridolin [San Diego State University, Department of Physics, San Diego, CA (United States); University of California San Diego, Center for Astrophysics and Space Sciences, La Jolla, CA (United States); Contrera, Gustavo A. [CONICET, Buenos Aires (Argentina); CONICET - Dept. de Fisica, UNLP, IFLP, La Plata (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina); Orsaria, Milva G. [CONICET, Buenos Aires (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina)

    2016-03-15

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (

  2. Improved measurements of the neutrino mixing angle $\\theta_{13}$ with the Double Chooz detector

    Abe, Y; Barriere, J C; Baussan, E; Bekman, I; Bergevin, M; Bezerra, T J C; Bezrukov, L; Blucher, E; Buck, C; Busenitz, J; Cabrera, A; Caden, E; Camilleri, L; Carr, R; Cerrada, M; Chang, P -J; Chauveau, E; Chimenti, P; Collin, A P; Conover, E; Conrad, J M; Crespo-Anadón, J I; Crum, K; Cucoanes, A S; Damon, E; Dawson, J V; Dietrich, D; Djurcic, Z; Dracos, M; Elnimr, M; Etenko, A; Fallot, M; von Feilitzsch, F; Felde, J; Fernandes, S M; Fischer, V; Franco, D; Franke, M; Furuta, H; Gil-Botella, I; Giot, L; Göger-Neff, M; Gonzalez, L F G; Goodenough, L; Goodman, M C; Grant, C; Haag, N; Hara, T; Haser, J; Hofmann, M; Horton-Smith, G A; Hourlier, A; Ishitsuka, M; Jochum, J; Jollet, C; Kaether, F; Kalousis, L N; Kamyshkov, Y; Kaplan, D M; Kawasaki, T; Kemp, E; de Kerret, H; Kryn, D; Kuze, M; Lachenmaier, T; Lane, C E; Lasserre, T; Letourneau, A; Lhuillier, D; Lima, H P; Lindner, M; López-Castaño, J M; LoSecco, J M; Lubsandorzhiev, B; Lucht, S; Maeda, J; Mariani, C; Maricic, J; Martino, J; Matsubara, T; Mention, G; Meregaglia, A; Miletic, T; Milincic, R; Minotti, A; Nagasaka, Y; Nikitenko, Y; Novella, P; Oberauer, L; Obolensky, M; Onillon, A; Osborn, A; Palomares, C; Pepe, I M; Perasso, S; Pfahler, P; Porta, A; Pronost, G; Reichenbacher, J; Reinhold, B; Röhling, M; Roncin, R; Roth, S; Rybolt, B; Sakamoto, Y; Santorelli, R; Schilithz, A C; Schönert, S; Schoppmann, S; Shaevitz, M H; Sharankova, R; Shimojima, S; Shrestha, D; Sibille, V; Sinev, V; Skorokhvatov, M; Smith, E; Spitz, J; Stahl, A; Stancu, I; Stokes, L F F; Strait, M; Stüken, A; Suekane, F; Sukhotin, S; Sumiyoshi, T; Sun, Y; Svoboda, R; Terao, K; Tonazzo, A; Thi, H H Trinh; Valdiviesso, G; Vassilopoulos, N; Veyssiere, C; Vivier, M; Wagner, S; Watanabe, H; Wiebusch, C; Winslow, L; Wurm, M; Yang, G; Yermia, F; Zimmer, V

    2014-01-01

    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\

  3. Revisiting the model predicting maximal 2–3 mixing and CP violation for neutrinos

    The model of the neutrino mass matrix that we proposed in 2000 is revisited in the light of the recent T2K experiments. This model has the special property that it predicts maximal 2–3 mixing and CP violation under some simple condition. In this model, if the condition is relaxed, the 2–3 angle and the CP violation deviate from their maximal values and are related. We present such relations for typical cases

  4. Neutrino Oscillations With Two Sterile Neutrinos

    Kisslinger, Leonard S

    2016-01-01

    This work estimates the probability of $\\mu$ to $e$ neutrino oscillation with two sterile neutrinos using a 5x5 U-matrix, an extension of the previous estimate with one sterile neutrino and a 4x4 U-matrix. The sterile neutrino-active neutrino mass differences and the mixing angles of the two sterile neutrinos with the three active neutrinos are taken from recent publications, and the oscillation probability for one sterile neutrino is compared to the previous estimate.

  5. D4 flavor symmetry for neutrino masses and mixing

    We present the D4xZ2 flavor symmetry, which is different from the previous work by Grimus and Lavoura. Our model reduces to the standard model in the low energy and there is no FCNC at the tree level. Putting the experimental data, parameters are fixed, and then the implication of our model is discussed. The condition to realize the tri-bimaximal mixing is presented. The possibility for stringy realization of our model is also discussed

  6. Neutrino Physics

    Langacker, Paul; Erler, Jens; Peinado, Eduardo

    2005-01-01

    The theoretical and experimental bases of neutrino mass and mixing are reviewed. A brief chronological evolution of the weak interactions, the electroweak Standard Model, and neutrinos is presented. Dirac and Majorana mass terms are explained as well as models such as the seesaw mechanism. Schemes for two, three and four neutrino mixings are presented.

  7. CP violation and neutrino masses and mixings from quark mass hierarchies

    Buchmueller, W.; Covi, L. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Emmanuel-Costa, D. [CFTP, Departamento de Fisica, Istituto Superior Tecnico, Lisbon (Portugal); Wiesenfeldt, S. [Illinois Univ., Urbana-Champaign, IL (United States). Dept. of Physics

    2007-10-15

    We study the connection between quark and lepton mass matrices in a supersymmetric SO(10) GUT model in six dimensions, compactified on an orbifold. The physical quarks and leptons are mixtures of brane and bulk states. This leads to a characteristic pattern of mass matrices and high-energy CP violating phases. The hierarchy of up and down quark masses determines the CKM matrix and most charged lepton and neutrino masses and mixings. The small hierarchy of neutrino masses is a consequence of the mismatch of the up and down quark mass hierarchies. The effective CP violating phases in the quark sector, neutrino oscillations and leptogenesis are unrelated. In the neutrino sector we can accomodate naturally sin {theta}{sub 23} {proportional_to}1, sin {theta}{sub 13}

  8. An A4 x Z4 model for neutrino mixing

    BenTov, Yoni; Zee, A

    2012-01-01

    The A4 x U(1) flavor model of He, Keum, and Volkas is extended to provide a minimal modification to tribimaximal mixing that accommodates a nonzero reactor angle theta13 ~ 0.1. The sequestering problem is circumvented by forbidding superheavy scales and large coupling constants which would otherwise generate sizable RG flows. The model is compatible with (but does not require) a stable or metastable dark matter candidate in the form of a complex scalar field with unit charge under a discrete subgroup Z4 of the U(1) flavor symmetry.

  9. Oscillating neutrinos

    After a general introduction into the mixing of muon and electron neutrinos due to a possible mass difference between these particles some experiments for the study of neutrino oscillations are described. (HSI).

  10. A field-theoretical approach to entanglement in neutrino mixing and oscillations

    Blasone, M; De Siena, S; Illuminati, F

    2014-01-01

    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.

  11. An A4-based see-saw model for realistic neutrino mass and mixing

    Pramanick, Soumita

    2015-01-01

    We present an $A4$-based model where neutrino masses arise from a combination of see-saw mechanisms. The model is motivated by several small mixing and mass parameters indicated by the data. These are $\\theta_{13}$, the solar mass splitting, and the small deviation of $\\theta_{23}$ from maximal mixing (= $\\pi/4$). We take the above as indications that at some level the small quantities are well-approximated by zero. In particular the mixing angles, to a zero order, should be either 0 or $\\pi/4$. Accordingly, in this model the Type-II see-saw dominates and generates the larger atmospheric mass splitting and sets $\\theta_{23} = \\pi/4$. The other mixing angles are vanishing as is the solar splitting. We show how the $A4$ assignment for the lepton doublets leads to this form. We also specify the $A4$ properties of the right-handed neutrinos which result in a smaller Type-I see-saw contribution that acts as a perturbation and shifts the angles $\\theta_{12}$ and $\\theta_{13}$ into the correct range and the desired ...

  12. Implications of recent data on neutrino mixing and lepton flavour violating decays for the Zee model

    He, Xiao-Gang; Majee, Swarup Kumar

    2012-03-01

    We study implications of recent data on neutrino mixing from T2K, MINOS, Double Chooz and μ → eγ from MEG for the Zee model. The simplest version of this model has been shown to be ruled out by experimental data some time ago. The general Zee model is still consistent with recent data. We demonstrate this with a constrained Zee model based on naturalness consideration. In this constrained model, only inverted mass hierarchy for neutrino masses is allowed, and θ 13 must be non-zero in order to have correct ratio for neutrino mass-squared differences and for mixing in solar and atmospherical neutrino oscillations. The best-fit value of our model for θ 13 is 8.91° from T2K and MINOS data, very close to the central value obtained by Double Chooz experiment. There are solutions with non-zero CP violation with the Jarlskog parameter predicted in the range ±0.039, ±0.044 and ±0.048 respectively for a 1 σ, 2 σ and 3 σ ranges of other input parameters. However, without any constraint on the θ 13-parameter above respective ranges become ±0.049, ±0.053 and ±0.056. We analyse different cases to obtain a branching ratio for μ → eγ close to the recent MEG bound. We also discuss other radiative as well as the charged trilepton flavour violating decay modes of the τ-lepton.

  13. Theoretical Results on Neutrinos

    Zhou, Shun

    2015-01-01

    In this talk, I first summarize our current knowledge about the fundamental properties of neutrinos and emphasize the remaining unsolved problems in neutrino physics. Then, recent theoretical results on neutrino mass models are introduced. Different approaches to understanding tiny neutrino masses, lepton flavor mixing and CP violation are presented. Finally, I report briefly some new progress in the studies of astrophysical neutrinos, including keV sterile neutrinos, supernova neutrinos and ultrahigh-energy cosmic neutrinos.

  14. Trimaximal TM1 neutrino mixing in S4 with spontaneous CP violation

    Luhn, Christoph

    2013-01-01

    The measurement of the reactor angle by the Daya Bay and RENO experiments in 2012 has ruled out the tri-bimaximal paradigm. Adopting an S4 family symmetry, we propose direct models of the trimaximal type TM1 in which the tri-bimaximal Klein symmetry of the neutrino sector is broken to a residual Z2 symmetry. In such a scenario, the solar mixing angle is decreased compared to its tri-bimaximal value by about one degree, thus bringing it in excellent agreement with experimental observation. The atmospheric mixing angle, on the other hand, depends on the CP violating Dirac phase delta. Imposing CP conservation in the family symmetry limit, we show how to break the CP symmetry via flavon VEVs with well-defined complex phases, so that sizable deviations of the atmospheric angle from maximal mixing, consistent with the latest global fits, are produced.

  15. Spontaneous breaking of flavor symmetry and naturalness of nearly degenerate neutrino masses and bi-maximal mixing

    2000-01-01

    The gauge model with SO(3)F flavor symmetry and three Higgs triplets is studied. We show how the intriguing nearly degenerate neutrino mass and bi-maximal mixing scenario comes out naturally after spontaneous breaking of the symmetry. The hierarchy between the neutrino mass-squared differences, which is needed for reconciling both solar and atmospheric neutrino data, naturally results from an approximate permutation symmetry. The model can also lead to interesting phenomena on lepton-flavor violations via the SO(3)F gauge interactions.

  16. Constraints on anomalous charged current couplings, tau neutrino mass and fourth generation mixing from tau leptonic branching fractions

    We use recent experimental measurements of tau branching fractions to determine the weak charged current magnetic and electric dipole moments of the tau and the Michel parameter η with unprecedented precision. These results are then used to constrain the tau compositeness scale and the allowed parameter space for Higgs doublet models. We also present new constraints on the mass of the tau neutrino and its mixing with a fourth generation neutrino

  17. Measuring the Leptonic CP Phase in Neutrino Oscillations with Non-Unitary Mixing

    Ge, Shao-Feng; Tortola, M; Valle, J W F

    2016-01-01

    Non-unitary neutrino mixing implies an extra CP violating phase that can fake the leptonic Dirac CP phase $\\delta_{CP}$ of the simplest three-neutrino mixing benchmark scheme. This would hinder the possibility of probing for CP violation in accelerator-type experiments. We take T2K and T2HK as examples to demonstrate the degeneracy between the "standard" (or "unitary") and "non-unitary" CP phases. We find, under the assumption of non-unitary mixing, that their CP sensitivities severely deteriorate. Fortunately, the TNT2K proposal of supplementing T2(H)K with a $\\mu$DAR source for better measurement of $\\delta_{CP}$ can partially break the CP degeneracy by probing both $\\cos \\delta_{CP}$ and $\\sin \\delta_{CP}$ dependences in the wide spectrum of the $\\mu$DAR flux. We also show that the further addition of a near detector to the $\\mu$DAR setup can eliminate the degeneracy completely.

  18. The 2-3 symmetry: Flavour Changing $b$, $\\tau$ Decays and Neutrino Mixing

    Datta, A; Datta, Alakabha; Donnell, Patrick J. O'

    2005-01-01

    The observed pattern of neutrino mixing may be the result of a 2-3($ \\mu- \\tau$) symmetry in the leptonic sector. We consider a two higgs doublet model with a 2-3 symmetry in the down type quark and the charged lepton sector. The breaking of the 2-3 symmetry by the strange quark mass and the muon mass leads to FCNC in the quark sector and the charged lepton sector that are suppressed by ${m_s \\over m_b}$ and ${m_{\\mu} \\over m_{\\tau}}$ in addition to the mass of the heavy higgs boson of the second higgs doublet. A higgs boson mass of $ m_H \\sim 900$ GeV can explain the deviation from standard model reported in several rare B decays. Predictions for other B decays are made and new CP phase is predicted in $B_{s}-{\\bar{B}_{s}}$ mixing. The lepton flavour violating decays $ \\tau \\to \\mu \\bar{l(q)} l(q)$ are below the experimental limits. The breaking of 2-3 symmetry in the lepton sector can lead to deviations of the atmospheric neutrino mixing angle from the maximal value by $ \\sim 2$ degrees.

  19. NuTeV anomaly, neutrino mixing, and a heavy Higgs boson

    Recent results from the NuTeV experiment at Fermilab and the deviation of the Z invisible width, measured at CERN LEP and the SLAC Linear Collider, from its standard model (SM) prediction suggest the suppression of neutrino-Z couplings. Such suppressions occur naturally in models which mix the neutrinos with heavy gauge singlet states. We postulate a universal suppression of the Zνν couplings by a factor of (1-ε) and perform a fit to the Z-pole and NuTeV observables with ε and the oblique correction parameters S and T. Compared to a fit with S and T only, the inclusion of ε leads to a dramatic improvement in the quality of the fit. The values of S and T preferred by the fit can be obtained within the SM by a simple increase in the Higgs boson mass. However, if the W mass is also included in the fit, a non-zero U parameter becomes necessary which cannot be supplied within the SM. The preferred value of ε suggests that the seesaw mechanism may not be the reason why neutrinos are so light

  20. Neutrino neutral current isoscalar excitations in 12C-isospin mixing, II

    The neutrino-neutral current isoscalar excitation of 12C( (1+; T = 0; 12.71 MeV) is investigated systematically to examine the specific roles of the various pieces of the neutral current. An effective Hamiltonian for the (isoscalar) neutrino-nucleus neutral current interaction is derived, within the context of the standard electroweak theory. The hadronic part of the neutral current interaction is found to be vectorial. Numerical results for the isoscalar total cross sections are found to satisfy the Primakoff inequality. The T = 1 admixture into the 12C( (1+; T = 0; 12.71 MeV) from the 12C( (1+; T = 1; 15.1 MeV) is taken into account. It is found that the isospin admixtures makes the total cross sections for the neutrino and antineutrino excitation of the 1+; 12.71 MeV in 12C different. The asymmetry R is thus a direct measure of T = 1 admixture. When the T-1 admixture is large (0.2), the Primakoff inequality is disturbed. Further effects of isospin mixing on the total cross sections are discussed

  1. Constructing the large mixing angle MNS matrix in see-saw models with right-handed neutrino dominance

    King, S F

    2002-01-01

    Recent SNO results strongly favour the large mixing angle (LMA) MSW solar solution. We argue that there are only two technically natural low energy neutrino mass matrix structures consistent with the LMA MSW solution, corresponding to either a hierarchy or an inverted hierarchy with pseudo-Dirac neutrinos. We first present a model-independent analysis in which we diagonalise each of these two mass matrix structures to leading order in $\\theta_{13}$ and extract the neutrino masses, mixing angles and phases. In this analysis we express the MNS matrix to leading order in the small angle $\\theta_{13}$ including the neutrino {\\em and} charged lepton mixing angles and phases, the latter playing a crucial r\\^{o}le for allowing the inverted hierarchy solution to be consistent with the LMA MSW solution. We then consider the see-saw mechanism with right-handed neutrino dominance and show how the successful neutrino mass matrix structures may be constructed with no tuning and with small radiative corrections, leading to...

  2. The Sensitivity of a Lithium Experiment on Solar Neutrinos to the Mixing Angle theta_{12}

    Kopylov, Anatoly; Petukhov, Valery

    2003-01-01

    A lithium-based radiochemical detector is aimed primarily to detect neutrinos from CNO cycle what will provide a direct proof of its existence and will be a stringent test of the theory of stellar evolution. Another task which can be solved by this experiment is to measure a mixing angle $\\theta_{12}$. The sensitivity of a lithium experiment to $\\theta_{12}$ was calculated by Monte-Carlo following the proposed original technique which can be used as a complimentary one to a chi-square techniq...

  3. Neutrino oscillations in non-inertial frames and the violation of the equivalence principle neutrino mixing induced by the equivalence principle violation

    Neutrino oscillations are analyzed in an accelerating and rotating reference frame, assuming that the gravitational coupling of neutrinos is flavor dependent, which implies a violation of the equivalence principle. Unlike the usual studies in which a constant gravitational field is considered, such frames could represent a more suitable framework for testing if a breakdown of the equivalence principle occurs, due to the possibility to modulate the (simulated) gravitational field. The violation of the equivalence principle implies, for the case of a maximal gravitational mixing angle, the presence of an off-diagonal term in the mass matrix. The consequences on the evolution of flavor (mass) eigenstates of such a term are analyzed for solar (oscillations in the vacuum) and atmospheric neutrinos. We calculate the flavor oscillation probability in the non-inertial frame, which does depend on its angular velocity and linear acceleration, as well as on the energy of neutrinos, the mass-squared difference between two mass eigenstates, and on the measure of the degree of violation of the equivalence principle (Δγ). In particular, we find that the energy dependence disappears for vanishing mass-squared difference, unlike the result obtained by Gasperini, Halprin, Leung, and other physical mechanisms proposed as a viable explanation of neutrino oscillations. Estimations on the upper values of Δγ are inferred for a rotating observer (with vanishing linear acceleration) comoving with the earth, hence ω∝7.10-5 rad/sec, and all other alternative mechanisms generating the oscillation phenomena have been neglected. In this case we find that the constraints on Δγ are given by Δγ≤102 for solar neutrinos and Δγ≤106 for atmospheric neutrinos. (orig.)

  4. Neutrino masses and large mixings as a indirect signature of grand unified theory

    Grand unified theory (GUT) unifies not only three forces (electromagnetic force, strong force and weak force) but also quarks and leptons. As an experimental support for the unification of forces, it is well-known that three gauge couplings meet at a scale (the GUT scale). However, it is not so well-known that there is an experimental support even for the unification of matters (quarks and leptons). We explain the indirect support in this document and show that the important key is what the neutrino experiments have revealed for 20 years. Concretely, for the unification of matters in SU(5) GUT, various observed hierarchies of quark and lepton masses and mixings can be understood only from one assumption that '10 dimensional fields of SU(5) induce stronger hierarchy for the Yukawa couplings than 5-bar fields'. For this explanation, the knowledges on neutrino masses and mixings are critical. In the end, we comment E6 unification in which the above assumption in the SU(5) GUT can be induced. (author)

  5. Neutrino emissivity in the quark-hadron mixed phase of neutron stars

    Spinella, William M; Contrera, Gustavo A; Orsaria, Milva G

    2015-01-01

    Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron m...

  6. Reactor Neutrinos

    Lasserre, T; Lasserre, Thierry; Sobel, Henry W.

    2005-01-01

    We review the status and the results of reactor neutrino experiments, that toe the cutting edge of neutrino research. Short baseline experiments have provided the measurement of the reactor neutrino spectrum, and are still searching for important phenomena such as the neutrino magnetic moment. They could open the door to the measurement of coherent neutrino scattering in a near future. Middle and long baseline oscillation experiments at Chooz and KamLAND have played a relevant role in neutrino oscillation physics in the last years. It is now widely accepted that a new middle baseline disappearance reactor neutrino experiment with multiple detectors could provide a clean measurement of the last undetermined neutrino mixing angle theta13. We conclude by opening on possible use of neutrinos for Society: NonProliferation of Nuclear materials and Geophysics.

  7. Majorana CP-violating phases, RG running of neutrino mixing parameters and charged lepton flavour violating decays

    We consider the MSSM with see-saw mechanism of neutrino mass generation and soft SUSY breaking with flavour-universal boundary conditions at the GUT scale, in which the lepton flavour violating (LFV) decays μ → e + γ, τ → μ + γ, etc., are predicted with rates that can be within the reach of present and planned experiments. These predictions depend critically on the matrix of neutrino Yukawa couplings Yν which can be expressed in terms of the light and heavy right-handed (RH) neutrino masses, neutrino mixing matrix UPMNS, , and an orthogonal matrix R. We investigate the effects of Majorana CP-violation phases in UPMNS, and of the RG running of light neutrino masses and mixing angles from MZ to the RH Majorana neutrino mass scale MR, on the predictions for the rates of LFV decays μ → e + γ, τ → μ + γ, and τ →e + γ. Results for neutrino mass spectrum with normal hierarchy, values of the lightest ν-mass in the range 0 ≤ m1 ≤ 0.30 eV, and quasi-degenerate heavy RH Majorana neutrinos in the cases of R = 1 and complex matrix R are presented. We find that the effects of the Majorana CP-violation phases and of the RG evolution of neutrino mixing parameters can change by few orders of magnitude the predicted rates of the LFV decays μ → e + γ, and τ → e + γ. The impact of these effects on the τ → μ + γ decay rate is typically smaller and only possible for m1 ≥ or approx. 0.10 eV. If the RG running effects are negligible, in a large region of soft SUSY breaking parameter space the ratio of the branching ratios of the μ → e + γ and τ →e + γ (τ → μ + γ) decays is entirely determined in the case of R ≅ 1 by the values of the neutrino mixing parameters at MZ. (author)

  8. Neutrino anomalies without oscillations

    Sandip Pakvasa

    2000-01-01

    I review explanations for the three neutrino anomalies (solar, atmospheric and LSND) which go beyond the `conventional' neutrino oscillations induced by mass-mixing. Several of these require non-zero neutrino masses as well.

  9. Intrinsic deviation from the tri-bimaximal neutrino mixing in a class of A4 flavor models

    It is well known that the tri-bimaximal neutrino mixing pattern V0 can be derived from a class of flavor models with the non-Abelian A4 symmetry. We point out that small corrections to V0, which are inherent in the A4 models and arise from both the charged-lepton and neutrino sectors, have been omitted in the previous works. We show that such corrections may lead the 3x3 neutrino mixing matrix V to a non-unitary deviation from V0, but they cannot result in a nonzero value of θ13 or any new CP-violating phases. Current experimental constraints on the unitarity of V allow us to constrain the model parameters to some extent.

  10. Abelian family symmetries and the simplest models that give theta13=0 in the neutrino mixing matrix

    Low, C I

    2005-01-01

    I construct predictive models of neutrino mass and mixing that have fewer parameters, both in the lepton sector and overall, than the default seesaw model. The predictions are theta13=0 and one massless neutrino, with the models having a Z4 or Z2 symmetry and just one extra degree of freedom: one real singlet Higgs field. It has been shown that models with an unbroken family symmetry, and with no Higgs fields other than the Standard Model Higgs doublet produce masses and mixing matrices that have been ruled out by experiment. Therefore, this article investigates the predictions of models with Abelian family symmetries that involve Higgs singlets, doublets and triplets, in the hope that they may produce the maximal and minimal mixing angles seen in the best fit neutrino mixing matrix. I demonstrate that these models can only produce mixing angles that are zero, maximal or unconfined by the symmetry. The maximal mixing angles do not correspond to physical mixing, so an Abelian symmetry can, at best, ensure that...

  11. Are Neutrinos Democratic?

    Karl, G

    2002-01-01

    We generalize the notion of democratic mixing matrices for neutrinos and propose a scheme in which the electron neutrino is a superposition of three different mass eigenstates with equal weights. This scheme accounts for the recent SNO results as well as atmospheric muon neutrino and electron neutrino data. The outcomes of reactor neutrino and accelerator experiments are also discussed.

  12. Neutrino Masses and Deviation from Tri-bimaximal mixing in \\Delta(27) model with Inverse Seesaw Mechanism

    Abbas, M; Rashed, A; Sil, A

    2016-01-01

    We propose a scheme, based on \\Delta(27) flavor symmetry and supplemented by other discrete symmetries and inverse seesaw mechanism, where both the light neutrino masses and the deviation from tri-bimaximal mixing matrix can be linked to the source of lepton number violation. The hierarchies of the charged leptons are explained. We find that the quark masses including their hierarchies and the mixing can also be constructed in a similar way.

  13. The neutrino mixing matrix could (almost) be diagonal with entries {\\pm}1

    BenTov, Yoni

    2012-01-01

    It is consistent with the measurement of \\theta_13 ~ 0.15 by Daya Bay to suppose that, in addition to being unitary, the neutrino mixing matrix is also almost hermitian, and thereby only a small perturbation from diag(+1,-1,-1) in a suitable basis. We suggest this possibility simply as an easily falsifiable ansatz that has not already been studied, as well as to offer a potentially useful means of organizing the experimental data. We explore the phenomenological implications of this ansatz and parametrize one type of deviation from the leading order relation |V_e3| \\approx |V_\\tau 1|. We also emphasize the group-invariant angle between orthogonal matrices as a means of comparing to data. The discussion is purely phenomenological, without any attempt to derive the condition V{\\dag} \\approx V from a fundamental theory.

  14. Predictive Grand Unified Textures for Quark and Neutrino Masses and Mixings

    Berezhiani, Z G; Berezhiani, Zurab; Rossi, Anna

    2001-01-01

    We propose new textures for the fermion Yukawa matrices which aregeneralizations of the so-called Stech ansatz. We discuss how these texturescan be realized in supersymmetric grand unified models with horizontal symmetry$SU(3)_H$ among the fermion generations. In this framework the mass and mixinghierarchy of fermions (including neutrinos) can emerge in a natural way. Weemphasize the central role played by the $SU(3)_H$ adjoint Higgs field whichreduces $SU(3)_H$ to $U(2)_H$ at the GUT scale. A $SO(10)\\times SU(3)_H$ modelis presented in which the desired Yukawa textures can be obtained. Thephenomenological implications of these textures are thoroughly investigated.Among various realistic possibilities for the Clebsch factors between the quarkand lepton entries, we find three different solutions which provide excellentfits of the quark masses and CKM mixing angles. Interestingly, all thesesolutions predict the correct amount of CP violation via the CKM mechanism,and, in addition, lead to an appealing pattern o...

  15. From the measurement of the θ13 mixing angle to the search for geo-neutrinos: studying νe-bare with Double Chooz and Borexino

    Double Chooz is a reactor neutrino oscillation experiment which aims at measuring the θ13 mixing angle thanks to two identical detectors located at different distances from the two reactors of the Chooz nuclear power plant, in the French Ardennes. While the near detector will start taking data in fall 2014 to normalize the flux of the neutrinos emitted by the nuclear reactors, the far detector is running since April 2011 and allows to observe the neutrinos disappearance through the neutrino oscillation phenomenon. This thesis is also dedicated to the Borexino experiment which was designed to observe solar neutrinos. Due to its low background level as well as its position in a nuclear free country, Italy, Borexino is also sensitive to geo-neutrinos. This thesis presents both the Double Chooz and Borexino experiments, from the description of the detectors to the main results, with a special attention to the background and its rejection. Studies on the neutrino directionality with these two experiments are also detailed. In the case of Double Chooz, since the neutrinos are coming from the two nuclear reactors, the precision of the analysis method can be assessed. This thesis presents also for the first time the possibility to retrieve the initial direction of the neutrinos when the neutrons created in the inverse beta decay reactions are captured on hydrogen. In the case of Borexino, neutrino directionality information could facilitate the discrimination between geo-neutrinos and neutrinos from nuclear reactors. (author)

  16. A PRECISION MEASUREMENT OF THE NEUTRINO MIXING ANGLE THETA (SUB 13) USING REACTOR ANTINEUTRINOS AT DAYA BAY.

    KETTELL, S.; ET AL.

    2006-10-16

    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.

  17. Estimation of the systematic uncertainties of the measurement of the neutrino mixing angle theta 13 related to the trigger system of the Double Chooz Experiment

    Stüken, David Anselm

    2013-01-01

    The Double Chooz experiment, located in the Ardennes region next to the CHOOZ-B nuclear power plant, is a reactor antineutrino experiment to measure neutrino oscillations. It has been designed as precision experiment to measure the neutrino mixing angel theta13 with highest possible accuracy due to its small value close to zero. The electron antineutrinoflux emitted by the reactor cores is measured by two identical neutrino detectors located at different distances from the reactor cores. Each...

  18. Deviation from tri-bimaximal mixings through flavour twisters in inverted and normal hierarchical neutrino mass models

    N Nimai Singh; Monisa Rajkhowa; Abhijit Borah

    2007-10-01

    We explore a novel possibility for lowering the solar mixing angle (12) from tri-bimaximal mixings, without sacrificing the predictions of maximal atmospheric mixing angle (23 = 45°) and zero reactor angle (13 = 0°) in the inverted and normal hierarchical neutrino mass models having 2-3 symmetry. This can be done through the identification of a flavour twister term in the texture of neutrino mass matrix and the variation of such term leads to lowering of solar mixing angle. For the observed ranges of $ m_{21}^{2}$ and $ m_{23}^{2}$, we calculate the predictions on tan2 12 = 0.5, 0.45, 0.35 for different input values of the parameters in the neutrino mass matrix. We also observe a possible transition from inverted hierarchical model having even CP parity (Type-IHA) to inverted hierarchical model having odd CP parity (Type-IHB) in the first two mass eigenvalues, when there is a change in input values of parameters in the same mass matrix. The present work differs from the conventional approaches for the deviations from tri-bimaximal mixing, where the 2-3 symmetry is broken, leading to 23 ≠ 45° and 13 ≠ 0°.

  19. Experimental Neutrino Physics: Final Report

    Lane, Charles E.; Maricic, Jelena

    2012-09-05

    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.

  20. Optimizing the determination of the neutrino mixing angle θ13 from reactor data

    Khan, Amir N.; McKay, Douglas W.; Ralston, John P.

    2014-07-01

    The technical breakthroughs of multiple detectors developed by Daya Bay and RENO collaborations have gotten great attention. Yet the optimal determination of neutrino mixing parameters from reactor data depends on the statistical method and demands equal attention. We find that a straightforward method using minimal parameters will generally outperform a multi-parameter method by delivering more reliable values with sharper resolution. We review standard confidence levels and statistical penalties for models using extra parameters, and apply those rules to our analysis. We find that the methods used in recent work of the Daya Bay and RENO collaborations have several undesirable properties. The existing work also uses nonstandard measures of significance which we are unable to explain. A central element of the current methods consists of variationally fitting many more parameters than data points. As a result, the experimental resolution of sin2(2θ13) is degraded. The results also become extremely sensitive to certain model parameters that can be adjusted arbitrarily. The number of parameters to include in evaluating significance is an important issue that has generally been overlooked. The measures of significance applied previously would be consistent if and only if all parameters but one were considered to have no physical relevance for the experiment's hypothesis test. Simpler, more transparent methods can improve the determination of the mixing angle θ13 from reactor data, and exploit the advantages from superb hardware technique of the experiments. We anticipate that future experimental analysis will fully exploit those advantages.

  1. Total cross section measurement of muon neutrinos on isoscalar target. Exact determination of the electroweak mixing parameter

    The work presented in this thesis is concerned with high energy muon-neutrino nucleon interactions. The experiment was performed at CERN in 1984 using the CHARM marble target-calorimeter exposed to the 160 GeV narrow band beam. The experimental analysis is based on an event-by-event classification of neutral currents (NC) and charged currents (CC) interactions and on precise measurements of neutrinos and antineutrinos fluxes. This leads to precise measurements of CC total cross-sections of neutrinos and antineutrinos between 10 and 160 GeV and of NC to CC ratios of total cross-sections of events with hadron energy greater than 4 GeV: R neutrino and Rantineutrino. From the measurements of Rneutrino and of the ratio of CC total cross-sections of antineutrinos and neutrinos, we obtain a high precision value of the electroweak mixing angle. Comparison of this result with those obtained in proton-antiproton collisions make it possible to derive a measurement of electroweak radiative corrections and a precise determination of ρ

  2. Neutrino Lensing

    LUO Xin-Lian

    2009-01-01

    Due to the intrinsic properties of neutrinos, the gravitational lens effect for a neutrino should be more colorful and meaningful than the normal lens effect of a photon. Other than the experiments operated at terrestrial laboratory, in principle, we can propose a completely new astrophysical method to determine not only the nature of the gravity of lens objects but also the mixing parameters of neutrinos by analyzing neutrino trajectories near the central objects.However, the angular, energy and time resolution of the neutrino telescopes are still comparatively poor, so we just concentrate on the two classical tests of general relativity, i.e.the angular deflection and the time delay of the neutrino by a lens object as a preparative work in this paper.In addition, some simple properties of neutrino lensing are investigated.

  3. Predictions for fermion masses and mixing from a low energy SU(3) flavor symmetry model with a Light Sterile Neutrino

    Galeana, Albino Hernandez

    2011-01-01

    I report low energy results on the study of fermion masses and mixing for quarks and leptons, including neutrinos within a SU(3) flavor symmetry model, where ordinary heavy fermions, top and bottom quarks and tau lepton become massive at tree level from {\\bf Dirac See-saw} mechanisms implemented by the introduction a new set of $SU(2)_L$ weak singlet vector-like fermions $U,D,E,N$, with $N$ a sterile neutrino. Light fermions obtain masses from one loop radiative corrections mediated by the massive SU(3) gauge bosons. Recent results shows the existence of a low energy space parameter where this model is able to accommodate the known spectrum of quark masses and mixing in a $4\\times 4$ non-unitary $V_{CKM}$ as well as the charged lepton masses. Motivated by the recent LSND and MiniBooNe short-baseline neutrino oscillation experiments we fit for the 3+1 scenario the neutrino squared mass differences $m_2^2 - m_1^2\\approx 7.6\\times 10^{-5}\\;\\text{eV}^2$, $m_3^2 - m_2^2\\approx 2.43\\times 10^{-3} \\text{eV}^2$ and $...

  4. Neutrino Mass Models

    King, S. F.

    2003-01-01

    This is a review article about neutrino mass models, particularly see-saw models involving three active neutrinos which are capable of describing both the atmospheric neutrino oscillation data, and the large mixing angle MSW solar solution, which is now uniquely specified by recent data. We briefly review the current experimental status, show how to parametrise and construct the neutrino mixing matrix, and present the leading order neutrino Majorana mass matrices. We then introduce the see-sa...

  5. Measurement of the neutrino mass splitting and flavor mixing by MINOS

    Adamson, P.; Andreopoulos, C.; Armstrong, R.; Auty, D. J.; Ayres, D. S.; Backhouse, C.; Barr, G.; Bishai, M.; Blake, A.; Bock, G. J.; Devenish, N. E.; Falk, E.; Hartnell, J.; Lefeuvre, G.; et al, ...

    2011-01-01

    Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of $7.25 \\times 10^{20}$ protons on target. A fit to neutrino oscillations yields values of $|\\Delta m^2| = (2.32^{+0.12}_{-0.08})\\times10^{-3}$\\,eV$^2$ for the atmospheric mass splitting and $\\rm \\sin^2\\!(2\\theta) > 0.90$ (90%\\,C.L.) for the m...

  6. Neutrino masses and tribimaximal mixing in Minimal renormalizable SUSY SU(5) Grand Unified Model with A4 Flavor symmetry

    Ciafaloni, Paolo; Torrente-Lujan, Emilio; Urbano, Alfredo

    2009-01-01

    We analyze all possible extensions of the recently proposed minimal renormalizable SUSY SU(5) grand unified model with the inclusion of an additional A4 flavor symmetry. We find that there are 5 possible Cases but only one of them is phenomenologically interesting. We develop in detail such Case and we show how the fermion masses and mixing angles come out. As prediction we obtain the neutrino masses of order of 0.1 eV with an inverted hierarchy.

  7. Effect of cross-section models on the validity of sterile neutrino mixing limits

    Stowell, Patrick; Cartwright, Susan

    2015-01-01

    Charged-Current Quasi-Elastic (CCQE) neutrino scattering is the signal channel for sterile neutrino oscillation experiments. Recent cross-section measurements have made it clear that the current understanding of this channel in the few-GeV region is incomplete, and several sophisticated theoretical models have been proposed to tackle this issue, although it is not clear which model best describes the global dataset. In this paper we argue that the current uncertainty surrounding CCQE cross-sections is a serious problem for experiments seeking to produce sterile neutrino limits. We perform a sterile neutrino analysis with published MINERvA data as an illustrative example. We highlight the need for caution in interpreting sterile neutrino limits given the context of incomplete cross-section model information.

  8. 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

    2015-01-01

    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...

  9. Does DaYa-Bay reactor neutrino experiment play an important role in θ13 of lepton mixing (PMNS) matrix?

    Reactor neutrinos play an important role in determining parameter θ13 in the lepton mixing (PMNS) matrix. An important step on measuring PMNS matrix could be to build another reactor neutrino experiment in DaYa Bay, China, to search the possible oscillations via sin2 2θ13 and Δm132. We consider 4 different schemes for positions of three 8-ton detectors of this experiment, and simulate the results with respect to an array of assumed 'true' values of physics parameters. Using three kinds of analysis methods, we suggest a best scheme for DaYa-Bay which is to place a detector 2200m ∼ 2500m symmetrically away from two reactors, and to put the other two detectors closer to their corresponding reactors respectively, almost at a 100m ∼ 200m distance. Moreover, with conservative assumption on the experimental technique, we construct series of allowed regions from our simulation results, and give detailed explanations therein. The movable detectors in DaYa-Bay can measure solar neutrino parameters in the next phase. (author)

  10. Neutrino refraction by the cosmic neutrino background

    Diaz, J S

    2015-01-01

    We have determined the dispersion relation of a neutrino test particle propagating in the cosmic neutrino background. Describing the relic neutrinos and antineutrinos from the hot big bang as a dense medium, a matter potential or refractive index is obtained. The vacuum neutrino mixing angles are unchanged, but the energy of each mass state is modified. Using a matrix in the space of neutrino species, the induced potential is decomposed into a part which produces signatures in beta-decay experiments and another part which modifies neutrino oscillations. The low temperature of the relic neutrinos makes a direct detection extremely challenging. From a different point of view, the identified refractive effects of the cosmic neutrino background constitute an ultralow background for future experimental studies of nonvanishing Lorentz violation in the neutrino sector.

  11. Neutrino refraction by the cosmic neutrino background

    Díaz, J. S.; Klinkhamer, F. R.

    2016-03-01

    We have determined the dispersion relation of a neutrino test particle propagating in the cosmic neutrino background. Describing the relic neutrinos and antineutrinos from the hot big bang as a dense medium, a matter potential or refractive index is obtained. The vacuum neutrino mixing angles are unchanged, but the energy of each mass state is modified. Using a matrix in the space of neutrino species, the induced potential is decomposed into a part which produces signatures in beta-decay experiments and another part which modifies neutrino oscillations. The low temperature of the relic neutrinos makes a direct detection extremely challenging. From a different point of view, the identified refractive effects of the cosmic neutrino background constitute an ultralow background for future experimental studies of nonvanishing Lorentz violation in the neutrino sector.

  12. Limits on heavy neutrino mixing from the beta decay of 38mK confined in a magneto-optical trap

    This thesis details the search for mixing between electron neutrinos and possible heavy neutrinos using the positron decay of 38mK produced at ISAC, TRIUMF's new radioactive beam facility. Using the novel technique of laser atom trapping to confine 38mK, direct limits on such mixing in β-decay are determined for the mass range of 0.7 MeV/c2 to 3.8 MeV/c2. The results, for part of this mass range, provide the best direct limits for the mixing of heavy neutrinos with the electron neutrino in the literature to date. The Standard Model of electroweak physics has been able to describe a wide range of experimental results, but an unresolved question arises in accounting for lepton masses. The charged leptons (electrons, muons and taus) have masses which vary enormously from one to another (me = 0.511 MeV/c2, mμ = 106 MeV/c2, mτ = 1777 MeV/c2), while their accompanying neutrinos appear to have no (or very little) mass. If neutrinos have finite mass, then mixing could occur among the different neutrino species. Thus, evidence of mixing would indicate the existence of non-zero neutrino mass and of the need to modify or extend the Standard Model. Consequently, this is a highly active field of physics. Evidence of possible neutrino mass and oscillation has been recently observed by the detection of energetic neutrinos from the atmosphere. The TRINAT collaboration at TRIUMF has searched for evidence of physics beyond the Standard Model using a radioactive source of 38mK atoms held in a neutral atom trap. The trap provides a source of several thousand atoms confined to a volume of less than a cubic millimeter, suspended in a vacuum vessel, in which the 38mK undergoes radioactive decay with the emission of a positron and a neutrino. This results in the creation of a daughter nucleus, 38Ar, with momentum equal to the vector sum of the momenta of the positron and the neutrino. The unperturbed nucleus then recoils from the trap and is detected in coincidence with the positron

  13. Limits on heavy neutrino mixing from the beta decay of {sup 38m}K confined in a magneto-optical trap

    Trinczek, M.C

    2001-07-01

    This thesis details the search for mixing between electron neutrinos and possible heavy neutrinos using the positron decay of {sup 38m}K produced at ISAC, TRIUMF's new radioactive beam facility. Using the novel technique of laser atom trapping to confine {sup 38m}K, direct limits on such mixing in {beta}-decay are determined for the mass range of 0.7 MeV/c{sup 2} to 3.8 MeV/c{sup 2}. The results, for part of this mass range, provide the best direct limits for the mixing of heavy neutrinos with the electron neutrino in the literature to date. The Standard Model of electroweak physics has been able to describe a wide range of experimental results, but an unresolved question arises in accounting for lepton masses. The charged leptons (electrons, muons and taus) have masses which vary enormously from one to another (m{sub e} = 0.511 MeV/c{sup 2}, m{sub {mu}} = 106 MeV/c{sup 2}, m{sub {tau}} = 1777 MeV/c{sup 2}), while their accompanying neutrinos appear to have no (or very little) mass. If neutrinos have finite mass, then mixing could occur among the different neutrino species. Thus, evidence of mixing would indicate the existence of non-zero neutrino mass and of the need to modify or extend the Standard Model. Consequently, this is a highly active field of physics. Evidence of possible neutrino mass and oscillation has been recently observed by the detection of energetic neutrinos from the atmosphere. The TRINAT collaboration at TRIUMF has searched for evidence of physics beyond the Standard Model using a radioactive source of {sup 38m}K atoms held in a neutral atom trap. The trap provides a source of several thousand atoms confined to a volume of less than a cubic millimeter, suspended in a vacuum vessel, in which the {sup 38m}K undergoes radioactive decay with the emission of a positron and a neutrino. This results in the creation of a daughter nucleus, 38{sup Ar}, with momentum equal to the vector sum of the momenta of the positron and the neutrino. The

  14. Global analyses of neutrino oscillation experiments

    Gonzalez-Garcia, M. C.; Maltoni, Michele; Schwetz, Thomas

    2016-07-01

    We summarize the determination of some neutrino properties from the global analysis of solar, atmospheric, reactor, and accelerator neutrino data in the framework of three-neutrino mixing as well as in some extended scenarios such as the mixing with eV-scale sterile neutrinos invoked for the interpretation of the short baseline anomalies, and the presence of non-standard neutrino interactions.

  15. Neutrino electromagnetic properties

    Giunti, Carlo

    2008-01-01

    The main goal of the paper is to give a short review on a neutrino electromagnetic properties. In the introductory part of the paper a summary on what we really know about neutrinos is given: we discuss the basics of neutrino mass and mixing as well as the phenomenology of neutrino oscillations. This is important for the further discussion on a neutrino electromagnetic properties that starts with derivation of the neutrino electromagnetic vertex function in the most general form, that follows from the requirement of Lorentz invariance, for both the Dirac and Majorana cases. Then the problem of a neutrino form factors definition and calculation within gauge models is considered. In particular, we discuss a neutrino electric charge form factor and charge radius, dipole magnetic and electric and anapole form factors. Available experimental constraints on a neutrino electromagnetic properties are also reviewed, and the most important experiments on obtaining limits on a neutrino magnetic moment are discussed. A s...

  16. Acquire information about neutrino parameters by detecting supernova neutrinos

    Huang, Ming-Yang; Guo, Xin-Heng; Young, Bing-Lin

    2010-01-01

    We consider the supernova shock effects, the Mikheyev-Smirnov-Wolfenstein (MSW) effects, the collective effects, and the Earth matter effects in the detection of type II supernova neutrinos on the Earth. It is found that the event number of supernova neutrinos depends on the neutrino mass hierarchy, the neutrino mixing angle $\\theta_{13}$, and neutrino masses. Therefore, we propose possible methods to identify the mass hierarchy and acquire information about $\\theta_{13}$ and neutrino masses ...

  17. $T_7$ flavor symmetry scheme for understanding neutrino mass and mixing in 3-3-1 model with neutral leptons

    Vien, V V

    2015-01-01

    We construct a new version for the 3-3-1 model based on $T_7$ flavor symmetry where the left-handed leptons under $T_7$ differ from those of our previous work while the $\\mathrm{SU}(3)_C \\otimes \\mathrm{SU}(3)_L \\otimes \\mathrm{U}(1)_X$ gauge symmetry is retain. The flavor mixing patterns and mass splitting are obtained without perturbation. The realistic lepton mixing can be obtained if both the direction of breakings $T_7 \\rightarrow Z_3$ and $Z_3 \\rightarrow \\{\\mathrm{Identity}\\}$ are taken place in neutrino sector. Maximal CP violation is predicted and CKM matrix is the identity matrix at the tree-level.

  18. Breaking eightfold degeneracies in neutrino CP violation, mixing, and mass hierarchy

    We identify three independent twofold parameter degeneracies (δ,θ13), sgn(δm312) and (θ23,π/2-θ23) inherent in the usual three-neutrino analysis of long-baseline neutrino experiments, which can lead to as much as an eightfold degeneracy in the determination of the oscillation parameters. We discuss the implications these degeneracies have for detecting CP violation and present criteria for breaking them. A superbeam facility with a baseline at least as long as the distance between Fermilab and Homestake (1290 km) and a narrow band beam with energy tuned so that the measurements are performed at the first oscillation peak can resolve all the ambiguities other than the (θ23,π/2-θ23) ambiguity (which can be resolved at a neutrino factory) and a residual (δ,π-δ) ambiguity. However, whether or not CP violation occurs in the neutrino sector can be ascertained independently of the latter two ambiguities. The (δ,π-δ) ambiguity can be eliminated by performing a second measurement to which only the cos δ terms contribute. The hierarchy of mass eigenstates can be determined at other oscillation peaks only in the most optimistic conditions, making it necessary to use the first oscillation maximum. We show that the degeneracies may severely compromise the ability of the proposed SuperJHF-HyperKamiokande experiment to establish CP violation. In our calculations we use approximate analytic expressions for oscillation probabilities that agree with numerical solutions with a realistic Earth density profile

  19. Breaking eightfold degeneracies in neutrino CP violation, mixing, and mass hierarchy

    Barger, V.; Marfatia, D.; Whisnant, K.

    2002-04-01

    We identify three independent twofold parameter degeneracies (δ,θ13), sgn(δm231) and (θ23,π/2-θ23) inherent in the usual three-neutrino analysis of long-baseline neutrino experiments, which can lead to as much as an eightfold degeneracy in the determination of the oscillation parameters. We discuss the implications these degeneracies have for detecting CP violation and present criteria for breaking them. A superbeam facility with a baseline at least as long as the distance between Fermilab and Homestake (1290 km) and a narrow band beam with energy tuned so that the measurements are performed at the first oscillation peak can resolve all the ambiguities other than the (θ23,π/2-θ23) ambiguity (which can be resolved at a neutrino factory) and a residual (δ,π-δ) ambiguity. However, whether or not CP violation occurs in the neutrino sector can be ascertained independently of the latter two ambiguities. The (δ,π-δ) ambiguity can be eliminated by performing a second measurement to which only the cos δ terms contribute. The hierarchy of mass eigenstates can be determined at other oscillation peaks only in the most optimistic conditions, making it necessary to use the first oscillation maximum. We show that the degeneracies may severely compromise the ability of the proposed SuperJHF-HyperKamiokande experiment to establish CP violation. In our calculations we use approximate analytic expressions for oscillation probabilitites that agree with numerical solutions with a realistic Earth density profile.

  20. Breaking Eight-fold Degeneracies in Neutrino CP Violation, Mixing, and Mass Hierarchy

    Barger, V; Whisnant, K

    2002-01-01

    We identify three independent two-fold parameter degeneracies (\\delta, \\theta_{13}), sgn(\\delta m^2_{31}) and (\\theta_{23}, \\pi/2-\\theta_{23}) inherent in the usual three-neutrino analysis of long-baseline neutrino experiments, which can lead to as much as an eight-fold degeneracy in the determination of the oscillation parameters. We discuss the implications these degeneracies have for detecting CP violation and present criteria for breaking them. A superbeam facility with a baseline at least as long as the distance between Fermilab and Homestake (1290 km) and a narrow band beam with energy tuned so that the measurements are performed at the first oscillation peak can resolve all the ambiguities other than the (\\theta_{23}, \\pi/2-\\theta_{23}) ambiguity (which can be resolved at a neutrino factory) and a residual (\\delta, \\pi-\\delta) ambiguity. However, whether or not CP violation occurs in the neutrino sector can be ascertained independently of the latter two ambiguities. The (\\delta,\\pi-\\delta) ambiguity ca...

  1. Ambiguity in source flux of high-energy cosmic\\/astrophysical neutrinos Effects of bi-maximal mixing and quantum-gravity induced decoherence

    Ahluwalia, D V

    2001-01-01

    For high energy cosmic neutrinos Athar, Jezabek, and Yasuda (AJY) have recently shown that the existing data on neutrino oscillations suggests that cosmic neutrino flux at the AGN/GRB source, F(nu_e):F(nu_mu):F(nu_tau) approx 1:2:0, oscillates to F(nu_e):F(nu_mu):F(nu_tau) approx 1:1:1. These results can be confirmed at AMANDA, Baikal, ANTARES and NESTOR, and other neutrino detectors with a good flavor resolution. Here, we re-derive the AJY result from quasi bi-maximal mixing, and show that observation of F(nu_e):F(nu_mu):F(nu_tau) approx 1:1:1 does not necessarily establish cosmic neutrino flux at the AGN/GRB source to be F(nu_e):F(nu_mu):F(nu_tau) approx 1:2:0. We also note that if the length scale for the quantum-gravity induced de-coherence for astrophysical neutrinos is of the order of a Mpc, then independent of the MNS matrix, the Liu-Hu-Ge (LHG) mechanism would lead to flux equalization for the cosmic/astrophysical neutrinos.

  2. Neutrinos in particle physics, astronomy and cosmology

    ''Neutrinos in Particle Physics, Astronomy and Cosmology'' provides a comprehensive and up-to-date introduction to neutrino physics, neutrino astronomy and neutrino cosmology. The intrinsic properties and fundamental interactions of neutrinos are described, as is the phenomenology of lepton flavor mixing, seesaw mechanisms and neutrino oscillations. The cosmic neutrino background, stellar neutrinos, supernova neutrinos and ultrahigh-energy cosmic neutrinos, together with the cosmological matter-antimatter asymmetry and other roles of massive neutrinos in cosmology, are discussed in detail. This book is intended for researchers and graduate students in the fields of particle physics, particle astrophysics and cosmology. (orig.)

  3. Fermion masses and Neutrino mixing in an U(1)_H flavor symmetry model with hierarchical radiative generation for light charged fermion masses

    Hernandez-Galeana, Albino

    2007-01-01

    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)_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. Lepton mixing matrix, V_{PMNS}, is written completely in terms of the neutrino masses m_1, m_2 and m_3. Large lepton mixing for \\theta_{12} and \\theta_{23} are predicted in the range of values 0.7 \\lesssim \\sin^22\\theta_{12}\\lesssim 0.7772 and 0.87 \\lesssim \\sin^22\\thet...

  4. Neutrino masses and mixings in the baryon triality constrained minimal supersymmetric standard model

    Dreiner, Herbi K.; Hanussek, Marja; Kim, Jong-Soo; Kom, C. H.

    2011-01-01

    We discuss how the experimental neutrino oscillation data can be realized in the framework of the baryon triality ($B_3$) constrained supersymmetric Standard Model (cSSM). We show how to obtain phenomenologically viable solutions, which are compatible with the recent WMAP observations. We present results for the hierarchical, inverted and degenerate cases which illustrate the possible size and structure of the lepton number violating couplings. We work with a new, as yet unpublished version o...

  5. Solar neutrino oscillations

    The special properties of solar neutrinos that render this flux so uniquely important in searches for neutrino masses and flavor mixing are reviewed. The effects of matter, including density fluctuations and turbulence, on solar neutrino oscillations are explained through analogies with more familiar atomic physics phenomena

  6. Neutrino mass and mixing in a minimally-extended SU(2)LxU(1) model

    The standard electroweak model, i.e. the minimal SU(2)LxU(1) gauge model, is extended so as to incorporate three more ingredients: one right-handed neutrino singlet, one Higgs singlet and a second Higgs doublet. In such a scheme, four Majorana neutrinos emerge, with two of them (ω3 and ω4) forming a see-saw pair while the rest (ω2 and ω1) acquiring mass at one- and two-loop levels respectively. Their masses therefore exhibit a remarkable hierarchy: m1 2 3 4. Spontaneous breakdown of the presupposed lepton-number conservation gives rise to a Nambu-Goldstone boson (majoron), which allows ω4 and ω3 to have a rapid invisible decay mode at tree and one-loop levels respectively. An attempt is made to derive constraints to the model from a cosmological consideration and from analyses of experimental data on τ-lepton decays, neutrino oscillations and double beta decays. It is found that m4 is rather severely restricted (3 is allowed to take any value below the laboratory upper limit (31 MeV). (author)

  7. Neutrino Sources and Properties

    Vissani, Francesco

    2014-01-01

    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.

  8. Neutrino Oscillation Studies with Reactors

    Vogel, Petr; Zhang, Chao

    2015-01-01

    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.

  9. Status of Neutrino Oscillations

    J.W.F. Valle

    2001-01-01

    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 hi...

  10. Measurement of neutrino mixing angle θ13 and mass difference Δ mee2 from reactor antineutrino disappearance in the RENO experiment

    Kim, Soo-Bong

    2016-07-01

    RENO (Reactor Experiment for Neutrino Oscillation) made a definitive measurement of the smallest neutrino mixing angle θ13 in 2012, based on the disappearance of reactor electron antineutrinos. The experiment has obtained a more precise value of the mixing angle and the first result on neutrino mass difference Δ mee2 from an energy and baseline dependent reactor neutrino disappearance using ∼500 days of data. Based on the ratio of inverse-beta-decay (IBD) prompt spectra measured in two identical far and near detectors, we obtain sin2 ⁡ (2θ13) = 0.082 ± 0.009 (stat .) ± 0.006 (syst .) and | Δ mee2 | = [2.62-0.23+0.21 (stat .)-0.13+0.12 (syst .) ] ×10-3 eV2. An excess of reactor antineutrinos near 5 MeV is observed in the measured prompt spectrum with respect to the most commonly used models. The excess is found to be consistent with coming from reactors. A successful measurement of θ13 is also made in an IBD event sample with a delayed signal of neutron capture on hydrogen. A precise value of θ13 would provide important information on determination of the leptonic CP phase if combined with a result of an accelerator neutrino beam experiment.

  11. A unified analysis of the reactor neutrino program towards the measurement of the {theta}{sub 13} mixing angle

    Mention, G.; Motta, D. [DAPNIA/SPP, CEA Saclay, 91191 Gif sur Yvette (France); Lasserre, Th. [DAPNIA/SPP, CEA Saclay, 91191 Gif sur Yvette (France); Laboratoire Astroparticule et Cosmologie (APC), Paris (France)

    2007-04-15

    We present in this article a detailed quantitative discussion of the measurement of the leptonic mixing angle {theta}{sub 13} through currently scheduled reactor neutrino oscillation experiments. We thus focus on Double Chooz (Phase I and II), Daya Bay (Phase I and II) and RENO experiments. We perform a unified analysis, including systematics, backgrounds and accurate experimental setup in each case. Each identified systematic error and background impact has been assessed on experimental setups following published data when available and extrapolating from Double Chooz acquired knowledge otherwise. After reviewing the experiments, we present a new analysis of their sensitivities to sin{sup 2}(2{theta}{sub 13}) and study the impact of the different systematics based on the pulls approach. Through this generic statistical analysis we discuss the advantages and drawbacks of each experimental setup. (authors)

  12. A unified analysis of the reactor neutrino program towards the measurement of the θ13 mixing angle

    We present in this article a detailed quantitative discussion of the measurement of the leptonic mixing angle θ13 through currently scheduled reactor neutrino oscillation experiments. We thus focus on Double Chooz (Phase I and II), Daya Bay (Phase I and II) and RENO experiments. We perform a unified analysis, including systematics, backgrounds and accurate experimental setup in each case. Each identified systematic error and background impact has been assessed on experimental setups following published data when available and extrapolating from Double Chooz acquired knowledge otherwise. After reviewing the experiments, we present a new analysis of their sensitivities to sin2(2θ13) and study the impact of the different systematics based on the pulls approach. Through this generic statistical analysis we discuss the advantages and drawbacks of each experimental setup. (authors)

  13. A Measurement of the Weak Mixing Angle in Neutrino-Nucleon Scattering at NuTeV

    Zeller, G P; Alton, A; Avvakumov, S; Bernstein, R H; Bodek, Arie; Bolton, T; Brau, J E; Buchholz, D A; Budd, H S; Bugel, L; Conrad, J; Drucker, R B; Formaggio, J A; Frey, R; Goldman, J; Goncharov, M; Harris, D A; Johnson, R A; Koutsoliotas, S; Kim, J H; Lamm, M J; Marsh, W; Mason, D; McNulty, C; McFarland, K S; Naples, D; Nienaber, P; Romosan, A; Sakumoto, W K; Schellman, H; Shaevitz, M H; Spentzouris, P; Stern, E G; Tamminga, B; Vakili, M; Vaitaitis, A G; Yang, U K

    1999-01-01

    The NuTeV experiment at Fermilab presents a determination of the electroweak mixing angle. High purity, large statistics samples of muon-neutrino and muon-antineutrino events allow the use of the Paschos-Wolfenstein relation. This considerably reduces systematic errors associated with charm production and other sources. With Standard Model assumptions, this measurement of sin2thw indirectly determines the W boson mass to a precision comparable to direct measurements from high energy e+e- and p-pbar colliders. NuTeV measures sin^2theta_W (on-shell) = 0.2253 +/- 0.0019(stat) +/- 0.0010(syst) which implies M_W = 80.26 +/- 0.11 GeV.

  14. Workshop on low energy neutrino physics

    The main topics of the workshop are: the determination of the neutrino mixing angle theta-13, the experiments concerning the monitoring of reactors based on the measurement of neutrino spectra, solar neutrinos, supernovae neutrinos, geo-neutrinos, neutrino properties, neutrinoless double beta decay and future low energy neutrino detectors. This document gathers together the program of the workshop, the slides of the presentations, some abstracts and some posters

  15. Effects of sudden mixing in the solar core on solar neutrinos and ice ages.

    Ezer, D.; Cameron, A. G. W.

    1972-01-01

    Some numerical experiments with a solar model have been conducted in connection with the hypothesis regarding the effects of mixing in the solar core. Questions concerning a plausible mechanism by which such a mixing could be produced are explored. The variation of solar luminosity throughout the numerical experiments is shown. In connection with a great change in luminosity after a second mixing, it is suggested that the earth is presently undergoing an ice age.

  16. Neutrino Physics (theory)

    Langacker, Paul

    2004-01-01

    Nonzero neutrino masses are the first definitive need to extend the standard model. After reviewing the basic framework, I describe the status of some of the major issues, including tests of the basic framework of neutrino masses and mixings; the question of Majorana vs. Dirac; the spectrum, mixings, and number of neutrinos; models, with special emphasis on constraints from typical superstring constructions (which are not consistent with popular bottom-up assumptions); and other implications.

  17. Neutrinos from a core collapse supernova

    Dighe, Amol

    2007-01-01

    The neutrino burst from a galactic supernova can help determine the neutrino mass hierarchy and $\\theta_{13}$, and provide crucial information about supernova astrophysics. Here we review our current understanding of the neutrino burst, flavor conversions of these neutrinos, and model independent signatures of various neutrino mixing scenarios.

  18. Physics of Neutrino Oscillation

    Mondal, Spandan

    2015-01-01

    The Standard Model of particle physics describes neutrinos as massless, chargeless elementary particles that come in three different flavours. However, recent experiments indicate that neutrinos not only have mass, but also have multiple mass eigenstates that are not identical to the flavour states, thereby indicating mixing. As an evidence of mixing, neutrinos have been observed to change from one flavour to another during their propagation, a phenomenon called neutrino oscillation. We have studied the reasons and derived the probabilities of neutrino flavour change, both in vacuum and in matter. We have also studied the parameters affecting this probability. We have discussed the special case of two-neutrino oscillations. Lastly, we have discussed some basic properties of neutrinos that are reflected in the previous derivations and highlighted a few relevant open problems. To begin with, we have also studied the relevant topics in introductory High Energy Physics and Quantum Mechanics to familiarize with th...

  19. Introduction to sterile neutrinos

    Volkas, R R

    2002-01-01

    Model-building issues raised by the prospect of light sterile neutrinos are discussed in a pedagogical way. I first review the na\\"{\\i}ve proposal that sterile neutrinos be identified with ``right handed neutrinos''. A critical discussion of the simple expedient of adding three gauge singlet fermions to the usual minimal standard model matter content is followed by an examination of right handed neutrinos in extended theories. I introduce the terminology of ``fully sterile'' and ``weakly sterile'' to classify varieties usually conflated under the sterile neutrino banner. After introducing the concepts of ``technical naturalness'' and plain ``naturalness'', the unbearable lightness of being a sterile neutrino is confronted. This problem is used to motivate mirror neutrinos, whose connection with pairwise maximal mixing is emphasised. Some brief remarks about phenomenology are made throughout. The impossibility of identifying the sole sterile neutrino of the currently favoured $2 + 2$ and $3 + 1$ phenomenologic...

  20. Supernova neutrinos and their oscillations

    The recent observations of neutrinos from a supernova have many implications for astrophysics and particle physics. Besides containing information on the supernova, the signal depends on the properties of neutrinos. In order to interpret the recent observations, the uncertainties in supernova dynamics must be disentangled from the effects of neutrino propagation. The authors concentrate on the mixing of neutrino fluxes from neutrino oscillations, both in vacuum and in matter

  1. Real Invariant Matrices and Flavour-Symmetric Mixing Variables with Emphasis on Neutrino Oscillations

    Harrison, P F.; Scott, W. G.(Particle Physics Department, Rutherford Appleton Laboratory, Didcot, UK); Weiler, T. J.

    2006-01-01

    In fermion mixing phenomenology, the matrix of moduli squared, P=(|U|^2), is well-known to carry essentially the same information as the complex mixing matrix U itself, but with the advantage of being phase-convention independent. The matrix K (analogous to the Jarlskog CP-invariant J) formed from the real parts of the mixing matrix "plaquette" products is similarly invariant. In this paper, the P and K matrices are shown to be entirely equivalent, both being directly related (in the leptonic...

  2. KamLAND potentiality on the determination of Neutrino mixing parameters in the post SNO-NC era

    Aliani, P; Picariello, M; Torrente-Lujan, E

    2003-01-01

    We study in detail the power of the reactor experiment kamLAND for discriminating existing solutions to the SNP and giving accurate information on neutrino masses and mixing angles. Assuming the expected signal corresponding to various ``benchmark'' points in the 2 dimensional $(\\Delta m^2,\\tan^2 \\theta)$ mixing plane, we develop a full-fledged $\\chi^2$ analysis which includes KamLAND spectrum and all the existing solar evidence. A complete modelling of statistical and known systematics errors for 1 and 3 years of data taking is also included, exclusion plots are presented. We find a much higher sensitivity especially for values of $\\Delta m^2$ lying in the central part of the LMA region. The situation would be more complicate for values closer to the border of the LMA region (the so called HLMA region, i.e. $\\Delta m^2 \\leq 2 \\times 10^{5}$ and $\\Delta m^2 \\geq 8-9 \\times 10^{-5}$ or $tan^2 \\theta$ far from $\\tan^2 \\theta = 0.5$). In this case kamLAND, with or without solar evidence, will be able only to sel...

  3. Direct Neutrino Mass Searches

    VanDevender, B. A.

    2009-12-01

    Neutrino flavor oscillation experiments have demonstrated that the three Standard Model neutrino flavor eigenstates are mixed with three mass eigenstates whose mass eigenvalues are nondegenerate. The oscillation experiments measure the differences between the squares of the mass eigenvalues but tell us nothing about their absolute values. The unknown absolute neutrino mass scale has important implications in particle physics and cosmology. Beta decay endpoint measurements are presented as a model-independent method to measure the absolute neutrino mass. The Karlsruhe Tritium Neutrino Experiment (KATRIN) is explored in detail.

  4. Long-Baseline Neutrino Experiments

    Diwan, M V; Qian, X; Rubbia, A

    2016-01-01

    We review long-baseline neutrino experiments in which neutrinos are detected after traversing macroscopic distances. Over such distances neutrinos have been found to oscillate among flavor states. Experiments with solar, atmospheric, reactor, and accelerator neutrinos have resulted in a coherent picture of neutrino masses and mixing of the three known flavor states. We will summarize the current best knowledge of neutrino parameters and phenomenology with our focus on the evolution of the experimental technique. We proceed from the first evidence produced by astrophysical neutrino sources to the current open questions and the goals of future research.

  5. Neutrino oscillation measurements with reactors

    McKeown, R.D.

    2010-01-01

    Since the first direct observations of antineutrino events by Reines and Cowan in the 1950's, nuclear reactors have been an important tool in the study of neutrino properties. More recently, the study of neutrino oscillations has been a very active area of research. The pioneering observation of oscillations by the KamLAND experiment has provided important information on the neutrino masses and the neutrino mixing matrix. New experiments to study the remaining unknown mixing angle are current...

  6. Cosmic Neutrino Flavor Democracy and Unitarity Violation at Neutrino Telescopes

    Xing, Zhi-zhong

    2008-01-01

    Provided ultrahigh-energy cosmic neutrinos are produced from the decays of charged pions arising from proton-proton and (or) proton-gamma collisions, their flavor ratios at a neutrino telescope will be \\phi^T_e : \\phi^T_\\mu : \\phi^T_\\tau \\approx 1 : 1 : 1. We show that the exact flavor democracy can occur if the unitary neutrino mixing matrix satisfies either \\theta_13 = 0 and \\theta_{23} = \\pi/4 (CP invariance) or \\delta= \\pm \\pi/2 and \\theta_{23} = \\pi/4 (CP violation) in the standard parametrization. Allowing for slight deviations from either condition, we calculate the corresponding neutrino flavor distribution at neutrino telescopes. If the neutrino mixing matrix is non-unitary, as expected in a class of seesaw models with TeV-scale Majorana neutrinos, we demonstrate that the effect of unitarity violation on the flavor democracy of cosmic neutrinos at neutrino telescopes can be as large as several percent.

  7. Sterile neutrinos at LBNE

    Hollander, David

    2014-01-01

    In this paper we examine the sensitivity of the Long Baseline Neutrino Oscillation Experiment to the inclusion of two new sterile neutrino flavors with masses in the eV range. We implement a modified Casas-Ibarra parametrization which can accommodate medium scale mass eigenstates and introduces a new complex mixing angle. We explore the new mixing angle parameter space and demonstrate how LBNE can be used to either provide evidence for or rule out a particular model of sterile neutrinos. Certain three-flavor CP-violation scenarios cannot be distinguished from the sterile neutrinos. Constraints from the Daya Bay reactor experiment are used to help lift this degeneracy.

  8. Yang-Mills duality as origin of generations, quark mixing and neutrino oscillations

    Tsou, S T

    2000-01-01

    The origin of fermion generations is one of the great mysteries in particle physics. We consider here a possible solution within the Standard Model framework based on a nonabelian generalization of electric-magnetic duality. First, nonabelian duality says that dual to the colour (electric) symmetry SU(3), there is a ``colour magnetic symmetry'' $\\widetilde{SU}(3)$, which by a result of 't~Hooft is spontaneously broken and can thus play the role of the "horizontal symmetry" of generations. Second, nonabelian duality suggests the manner this symmetry is broken with frame vectors in internal symmetry space acting as Higgs fields. As a result, mass matrices factorize leading to fermion mass hierarchy. A calculation to first order gives mixing (CKM and MNS) matrices in general agreement with experiment. In particular, quark mixing is seen naturally to be weak compared with leptons, while within the lepton sector, $\\mu-\\tau$ mixing turns out near maximal but $e-\\tau$ mixing small, just as seen in recent $\

  9. Impacts of the observed theta_{13} on the running behaviors of Dirac and Majorana neutrino mixing angles and CP-violating phases

    Luo, Shu; Xing, Zhi-zhong

    2012-01-01

    The recent observation of the smallest neutrino mixing angle $\\theta_{13}$ in the Daya Bay and RENO experiments motivates us to examine whether $\\theta_{13} \\simeq 9^\\circ$ at the electroweak scale can be generated from $\\theta_{13} = 0^\\circ$ at a superhigh-energy scale via the radiative corrections. We find that it is difficult but not impossible in the minimal supersymmetric standard model (MSSM), and a relatively large $\\theta_{13}$ may have some nontrivial impacts on the running behavior...

  10. Neutrino oscillations: From a historical perspective to the present status

    Bilenky, S.

    2016-07-01

    The history of neutrino mixing and oscillations is briefly presented. Basics of neutrino mixing and oscillations and convenient formalism of neutrino oscillations in vacuum are given. The role of neutrino in the Standard Model and the Weinberg mechanism of the generation of the Majorana neutrino masses are discussed.

  11. Neutrino oscillations: from an historical perspective to the present status

    Bilenky, S

    2016-01-01

    The history of neutrino mixing and oscillations is briefly presented. Basics of neutrino mixing and oscillations and convenient formalism of neutrino oscillations in vacuum is given. The role of neutrino in the Standard Model and the Weinberg mechanism of the generation of the Majorana neutrino masses are discussed.

  12. Sterile neutrino dark matter and core-collapse supernovae

    Mathews, Grant. J.; Warren, MacKenzie; Hidaka, Jun; Kajino, Toshitaka

    2016-01-01

    We have explored the impact of sterile neutrino dark matter on core-collapse supernova explosions. We have included oscillations between electron neutrinos or mixed $\\mu,\\tau$ neutrinos and right-handed sterile neutrinos into a supernova model. We have chosen sterile neutrino masses and mixing angles that are consistent with sterile neutrino dark matter candidates as indicated by recent x-ray flux measurements. Using these simulations, we have explored the impact of sterile neutrinos on the c...

  13. On the role of the rotations and Bogoliubov transformations in neutrino mixing

    Blasone, Massimo; Vitiello, Giuseppe

    2016-01-01

    We show that mixing transformations for Dirac fields arise as a consequence of the non-trivial interplay between rotations and Bogoliubov transformations at level of ladder operators. Indeed the non-commutativity between the algebraic generators of such transformations turns out to be responsible of the unitary inequivalence of the flavor and mass representations and of the associated vacuum structure. A possible thermodynamic interpretation is also investigated.

  14. Minimalistic Neutrino Mass Model

    De Gouvêa, A; Gouvea, Andre de

    2001-01-01

    We consider the simplest model which solves the solar and atmospheric neutrino puzzles, in the sense that it contains the smallest amount of beyond the Standard Model ingredients. The solar neutrino data is accounted for by Planck-mass effects while the atmospheric neutrino anomaly is due to the existence of a single right-handed neutrino at an intermediate mass scale between 10^9 GeV and 10^14 GeV. Even though the neutrino mixing angles are not exactly predicted, they can be naturally large, which agrees well with the current experimental situation. Furthermore, the amount of lepton asymmetry produced in the early universe by the decay of the right-handed neutrino is very predictive and may be enough to explain the current baryon-to-photon ratio if the right-handed neutrinos are produced out of thermal equilibrium. One definitive test for the model is the search for anomalous seasonal effects at Borexino.

  15. Progress in neutrino oscillation searches and their implications

    Srubabati Goswami

    2003-02-01

    Neutrino oscillation, in which a given flavor of neutrino transforms into another is a powerful tool for probing small neutrino masses. The intrinsic neutrino properties involved are neutrino mass squared difference 2 and the mixing angle in vacuum . In this paper I will summarize the progress that we have achieved in our search for neutrino oscillation with special emphasis on the recent results from the Sudbury Neutrino Observatory (SNO) on the measurement of solar neutrino fluxes. I will outline the current bounds on the neutrino masses and mixing parameters and discuss the major physics goals of future neutrino experiments in the context of the present picture.

  16. A field-theoretical approach to entanglement in neutrino mixing and oscillations

    Blasone, M.; Dell'Anno, F.; De Siena, S.; Illuminati, F.

    2014-01-01

    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 th...

  17. Results from neutrino experiments

    Recent (first or/and the best) results from the neutrino experiments are reviewed and their implications for the theory are discussed. The sense of the experiments is the searching for neutrino masses, mixing and interactions beyond the standard model. Present laboratory experiments give upper bounds on the masses and the mixing which are at the level of predictions of the ''electroweak see-saw''. Positive indications of nonzero lepton mixing follow from studies of the solar and atmospheric neutrinos. (author). 95 refs, 11 figs

  18. Neutrino Mass Models

    King, S F

    2004-01-01

    This is a review article about neutrino mass models, particularly see-saw models involving three active neutrinos which are capable of describing both the atmospheric neutrino oscillation data, and the large mixing angle MSW solar solution, which is now uniquely specified by recent data. We briefly review the current experimental status, show how to parametrise and construct the neutrino mixing matrix, and present the leading order neutrino Majorana mass matrices. We then introduce the see-saw mechanism, and discuss a natural application of it to current data using the sequential dominance mechanism, which we compare to an early proposal for obtaining large mixing angles. We show how both the Standard Model and the Minimal Supersymmetric Standard Model may be extended to incorporate the see-saw mechanism, and show how the latter case leads to the expectation of lepton flavour violation. The see-saw mechanism motivates models with additional symmetries such as unification and family symmetry models, and we tab...

  19. Low-energy neutrino physics and neutrino mass

    Boehm, F.; Vogel, P.

    1984-01-01

    Among the principal concerns in neutrino physics today are the questions of whether neutrinos are massive and, if so, whether the neutrinos emitted in a weak decay are pure or mixed quantum states. The concept of mixed neutrinos has been with us for more than 20 years, having first been introduced by Maki et al (1) and by Pontecorvo (2) following demonstration in 1962 that more than one type (flavor) of neutrino existed. After having been dormant for some time, the interest in these issues wa...

  20. Physics at neutrino factories

    Peach, Kenneth J

    2001-01-01

    There is increasing interest in using intense neutrino beams from a high-energy muon storage ring-the Neutrino Factory-to make precise measurements of the lepton mixing matrix, including the T-violating phase, as well as a diverse programme of other physics.

  1. Neutrino properties from ultra-high energy cosmic neutrinos

    Huang, Yanqi

    2015-01-01

    Neutrino properties can be constrained by the detection of ultra-high energy cosmic neutrinos (UHECNs). By using the updated global fitting results of neutrino mixing parameters, we present predictions on the neutrino flavor ratios at the Earth from three possibly astrophysical sources. Comparing with the latest IceCube data, we find that the normal hierarchy (NH) and inverted hierarchy (IH) cases from the initial ratios $\\phi_{\

  2. Observables in neutrino mass spectroscopy using atoms

    The process of collective de-excitation of atoms in a metastable level into emission mode of a single photon plus a neutrino pair, called radiative emission of neutrino pair (RENP), is sensitive to the absolute neutrino mass scale, to the neutrino mass hierarchy and to the nature (Dirac or Majorana) of massive neutrinos. We investigate how the indicated neutrino mass and mixing observables can be determined from the measurement of the corresponding continuous photon spectrum taking the example of a transition between specific levels of the Yb atom. The possibility of determining the nature of massive neutrinos and, if neutrinos are Majorana fermions, of obtaining information about the Majorana phases in the neutrino mixing matrix, is analyzed in the cases of normal hierarchical, inverted hierarchical and quasi-degenerate types of neutrino mass spectrum. We find, in particular, that the sensitivity to the nature of massive neutrinos depends critically on the atomic level energy difference relevant in the RENP

  3. Sudbury Neutrino Observatory

    Beier, E. W.

    1992-03-01

    This document is a technical progress report on work performed at the University of Pennsylvania during the current year on the Sudbury Neutrino Observatory project. The motivation for the experiment is the measurement of neutrinos emitted by the sun. The Sudbury Neutrino Observatory (SNO) is a second generation dedicated solar neutrino experiment which will extend the results of our work with the Kamiokande II detector by measuring three reactions of neutrinos rather than the single reaction measured by the Kamiokande experiment. The collaborative project includes physicists from Canada, the United Kingdom, and the United States. Full funding for the construction of this facility was obtained in Jan. 1990, and its construction is estimated to take five years. The motivation for the SNO experiment is to study the fundamental properties of neutrinos, in particular the mass and mixing parameters, which remain undetermined after decades of experiments in neutrino physics utilizing accelerators and reactors as sources of neutrinos. To continue the study of neutrino properties it is necessary to use the sun as a neutrino source. The long distance to the sun makes the search for neutrino mass sensitive to much smaller mass than can be studied with terrestrial sources. Furthermore, the matter density in the sun is sufficiently large to enhance the effects of small mixing between electron neutrinos and mu or tau neutrinos. This experiment, when combined with the results of the radiochemical Cl-37 and Ga-71 experiments and the Kamiokande II experiment, should extend our knowledge of these fundamental particles, and as a byproduct, improve our understanding of energy generation in the sun.

  4. Theoretical Aspects of Neutrino Physics

    Recent years have seen an extraordinary breakthrough in neutrino physics. Compelling experimental evidence indicates that, contrary to earlier believes, this fundamental particles have non zero masses and mix. Such properties are manifested in the oscillation phenomena in neutrino fluxes produced within the Sun, by cosmic rays, and in nuclear plants on the Earth, among other astrophysical and terrestrial sources. In these lecture we provide a short introduction to neutrino properties, mainly intended to give some basic elements of the physics of neutrino oscillations for beginners. We also discuss some of the theoretical questions raised on particle physics by the discovery of neutrino masses and mixings

  5. Introduction to neutrino physics

    Totsuka, Y

    2003-01-01

    An elementary particle 'neutrino' was born in Pauli's conjecture 70 years ago. Its study has made remarkable contributions to establishing the weak interactions and the electro-weak unification theory. Recently much interest has been directed to investigating the intrinsic properties of the neutrinos and important experimental results on their masses and mixings were obtained. This article introduces several experiments that have made breakthroughs in neutrino physics. Also presented is a personal view of what should be done in future to further develop neutrino physics. This article is devoted to Professor Koshiba's 2002 Nobel Prize in physics. (author)

  6. Eighty years of neutrino physics

    This is a pedagogical overview of neutrino physics from the invention of neutrino by Pauli in 1930 to the precise measurement of neutrino mass and mixing parameters via neutrino oscillation experiments in recent years. I have tried to pitch it at the level of undergraduate students, occasionally cutting corners to avoid the use of advanced mathematical tools. I hope it will be useful in introducing this exciting field to a broad group of young physicists. (author)

  7. Neutrino physics with JUNO

    An, Fengpeng; An, Guangpeng; An, Qi; Antonelli, Vito; Baussan, Eric; Beacom, John; Bezrukov, Leonid; Blyth, Simon; Brugnera, Riccardo; Buizza Avanzini, Margherita; 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, Hervé; 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; Göger-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, Cécile; 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; Möllenberg, 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, Yi; Wang, Yifang; Wang, Zhe; Wang, Zheng; Wang, Zhigang; Wang, Zhimin; Wei, Wei; Wen, Liangjian; Wiebusch, Christopher; Wonsak, Björn; 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, Frédéric; 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

    2016-03-01

    . Detection of neutrinos from all past core-collapse supernova explosions in the visible universe with JUNO would further provide valuable information on the cosmic star-formation rate and the average core-collapse neutrino energy spectrum. Antineutrinos originating from the radioactive decay of uranium and thorium in the Earth can be detected in JUNO with a rate of ˜400 events per year, significantly improving the statistics of existing geoneutrino event samples. Atmospheric neutrino events collected in JUNO can provide independent inputs for determining the MH and the octant of the {θ }23 mixing angle. Detection of the 7Be and 8B solar neutrino events at JUNO would shed new light on the solar metallicity problem and examine the transition region between the vacuum and matter dominated neutrino oscillations. Regarding light sterile neutrino topics, sterile neutrinos with {10}-5 {{{eV}}}2\\lt {{Δ }}{m}412\\lt {10}-2 {{{eV}}}2 and a sufficiently large mixing angle {θ }14 could be identified through a precise measurement of the reactor antineutrino energy spectrum. Meanwhile, JUNO can also provide us excellent opportunities to test the eV-scale sterile neutrino hypothesis, using either the radioactive neutrino sources or a cyclotron-produced neutrino beam. The JUNO detector is also sensitive to several other beyondthe-standard-model physics. Examples include the search for proton decay via the p\\to {K}++\\bar{ν } decay channel, search for neutrinos resulting from dark-matter annihilation in the Sun, search for violation of Lorentz invariance via the sidereal modulation of the reactor neutrino event rate, and search for the effects of non-standard interactions. The proposed construction of the JUNO detector will provide a unique facility to address many outstanding crucial questions in particle and astrophysics in a timely and cost-effective fashion. It holds the great potential for further advancing our quest to understanding the fundamental properties of neutrinos, one

  8. Pseudo-Dirac Scenario for Neutrino Oscillations

    Kobayashi, Makoto; Lim, C. S.

    2000-01-01

    We argue how pseudo-Dirac scenario for neutrinos leads to rich neutrino oscillation phenomena, including oscillation inside each generation. The pseudo-Dirac scenario is generalized by incorporating generation mixings and formulae for the various neutrino oscillations are derived. As the application we compare the formulae with the corresponding data. We find that observed pattern of mixings, such as almost maximal mixing in the atmospheric neutrino oscillation, is naturally explained in the ...

  9. Resurrection of large lepton number asymmetries from neutrino flavor oscillations

    Barenboim, Gabriela; Park, Wan-Il

    2016-01-01

    We numerically solve the evolution equations of neutrino three-flavor density matrices, and show that, even if neutrino oscillations mix neutrino flavors, large lepton number asymmetries are still allowed in certain limits by Big Bang Nucleosynthesis (BBN).

  10. Direct neutrino mass measurements

    Thümmler, T.

    2011-07-01

    The determination of the neutrino rest mass plays an important role at the intersections of cosmology, particle physics and astroparticle physics. This topic is currently being addressed by two complementary approaches in laboratory experiments. Neutrinoless double beta decay experiments probe whether neutrinos are Majorana particles and determine an effective neutrino mass value. Single beta decay experiments such as KATRIN and MARE investigate the spectral shape of β-decay electrons close to their kinematic endpoint in order to determine the neutrino rest mass with a model-independent method. Owing to neutrino flavour mixing, the neutrino mass parameter 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. Applying an ultra-luminous molecular windowless gaseous tritium source and an integrating high-resolution spectrometer of MAC-E filter type, it allows β-spectroscopy close to the T 2 end-point with unprecedented precision and will reach a sensitivity of 200 meV/ c 2 (90% C.L.) on the neutrino rest mass.

  11. Neutrino assisted gauge mediation

    Recent observation shows that the Higgs mass is at around 125 GeV while the prediction of the minimal supersymmetric standard model is below 120 GeV for stop mass lighter than 2 TeV unless the top squark has a maximal mixing. We consider the right-handed neutrino supermultiplets as messengers in addition to the usual gauge mediation to obtain sizeable trilinear soft parameters At needed for the maximal stop mixing. Neutrino messengers can explain the observed Higgs mass for stop mass around 1 TeV. Neutrino assistance can also generate charged lepton flavor violation including μ→e γ as a possible signature of the neutrino messengers. We consider the S4 discrete flavor model and show the relation of the charged lepton flavor violation, θ 13 of neutrino oscillation and the muon's g-2. (orig.)

  12. Los Alamos Science, Number 25 -- 1997: Celebrating the neutrino

    Cooper, N.G. [ed.

    1997-12-31

    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.

  13. Los Alamos Science, Number 25 -- 1997: Celebrating the neutrino

    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

  14. The Neutrino: Evidence of a Negative-Energy Vacuum State

    Daywitt W. C.

    2009-04-01

    Full Text Available This note argues that the neutrino is a phonon packet that exists and propagates within the negative-energy Planck vacuum. Simple calculations connect the three neutrinos to their corresponding leptons and show: that the neutrino mass is a ficticious or effective mass; that the neutrino mass cannot be zero; that each of the three neutrinos has a unique mass that determines its velocity; and that flavor (neutrino-type mixing does not involve mass mixing.

  15. Neutrino oscillations and supersymmetry

    The Super-Kamiokande experiment measured the atmospheric muon and electron neutrinos. The standard model predicts a ratio of 2, while Super-Kamiokande and others measure a much smaller value (1.30±0.02 for Super-Kamiokande). But Super-Kamiokande can also measure roughly the direction and the energy of the neutrinos. The zenith angle dependence for the muon neutrinos suggests that the muon neutrinos oscillate into a third neutrino species either into the τ neutrino or a sterile neutrino. This finding is investigated within the supersymmetric model. The neutrinos mix with the neutralinos, this means the wino, the bino and the two higgsinos. The 7 x 7 mass matrix is calculated on the tree level. One finds that the mass matrix has three linearly dependent rows which means, that two masses are zero. They are identified with the two lightest neutrino masses. The fit of the Super-Kamiokande data to oscillations between three neutrinos yields together with the result of supersymmetry that the third neutrino mass lies between 2 · 10-2 and 10-1 [eV]. The two lightest neutrino masses are in supersymmetry on the tree level zero. The averaged electron neutrino mass which is the essential parameter in the neutrinoless double beta decay νe> = mν3 · P3e ≤ 0.8 · 10-2 [eV] (95 % confidence limit). It is derived from the Super-Kamiokande data in this supersymmetric model to be two orders smaller than the best value (l[eV]) from the neutrinoless double beta decay. (author)

  16. Dimensional deconstruction and neutrino physics

    We present a simple observation for neutrino mixings and masses which arise naturally in dimensional deconstruction models. There are two essential ingredients of such models: (i) the presence of a symmetry mediated by the link fields which results in the neutrino mixings to be maximal; and (ii) a large deconstruction scale which gives rise to a small neutrino mass, similar in feature to the seesaw mechanism

  17. Dimensional Deconstruction and Neutrino Physics

    Balaji, K R S

    2005-01-01

    We present a simple observation for neutrino mixings and masses which arises naturally in dimensional deconstruction models. There are two essential ingredients of such models: (i) the presence of a symmetry mediated by the link fields which results in the neutrino mixings to be maximal; and (ii) a deconstruction scale which for large values gives rise to a small neutrino mass, similar in feature to the seesaw mechanism.

  18. Neutrino masses From fantasy to facts

    Valle, José W F

    1999-01-01

    Theory suggests the existence of neutrino masses, but little more. Facts are coming close to reveal our fantasy: solar and atmospheric neutrino data strongly indicate the need for neutrino conversions, while LSND provides an intriguing hint. The simplest ways to reconcile these data in terms of neutrino oscillations invoke a light sterile neutrino in addition to the three active ones. Out of the four neutrinos, two are maximally-mixed and lie at the LSND scale, while the others are at the solar mass scale. These schemes can be distinguished at neutral-current-sensitive solar & atmospheric neutrino experiments. I discuss the simplest theoretical scenarios, where the lightness of the sterile neutrino, the nearly maximal atmospheric neutrino mixing, and the generation of $\\Delta {m^2}_\\odot$ & $\\Delta {m^2}_{atm}$ all follow naturally from the assumed lepton-number symmetry and its breaking. Although the most likely interpretation of the present data is in terms of neutrino-mass-induced oscillations, one...

  19. Neutrino Masses, where do we stand?

    Valle, José W F

    1999-01-01

    I review the status of neutrino physics post-Neutrino~98, including the implications of solar and atmospheric neutrino data, which strongly indicate nonzero neutrino masses. LSND and the possible role of neutrinos as hot dark matter (HDM) are also mentioned. The simplest schemes proposed to reconcile these requirements invoke a light sterile neutrino in addition to the three active ones, two of them at the MSW scale and the other two maximally-mixed neutrinos at the HDM/LSND scale. In the simplest theory the latter scale arises at one-loop, while the solar and atmospheric parameters $\\Delta {m^2}_\\odot$ & neutrino, the nearly maximal atmospheric neutrino mixing, and the generation of lepton-number symmetry and its breaking. These two basic schemes can be distinguished at future solar & atmospheric neutrino experiments and have different cosmological implications.

  20. Radiative emission of neutrino pairs in atoms and light sterile neutrinos

    D.N. Dinh

    2015-03-01

    Full Text Available The process of Radiative Emission of Neutrino Pair (RENP in atoms is sensitive to the absolute neutrino mass scale, the type of spectrum neutrino masses obey and the nature – Dirac or Majorana – of massive neutrinos. We analyse the possibility to test the hypothesis of existence of neutrinos with masses at the eV scale coupled to the electron in the weak charged lepton current in an RENP experiment. The presence of eV scale neutrinos in the neutrino mixing is associated with the existence of sterile neutrinos which mix with the active flavour neutrinos. At present there are a number of hints for active–sterile neutrino oscillations driven by Δm2∼1 eV2. We perform a detailed analysis of the RENP phenomenology within the “3+1” scheme with one sterile neutrino.

  1. Cosmic Neutrinos

    Quigg, Chris; /Fermilab /CERN

    2008-02-01

    I recall the place of neutrinos in the electroweak theory and summarize what we know about neutrino mass and flavor change. I next review the essential characteristics expected for relic neutrinos and survey what we can say about the neutrino contribution to the dark matter of the Universe. Then I discuss the standard-model interactions of ultrahigh-energy neutrinos, paying attention to the consequences of neutrino oscillations, and illustrate a few topics of interest to neutrino observatories. I conclude with short comments on the remote possibility of detecting relic neutrinos through annihilations of ultrahigh-energy neutrinos at the Z resonance.

  2. The JHF-Kamioka neutrino project

    Itow, Y.; Kajita, T.; Kaneyuki, K.; Shiozawa, M; Totsuka, Y.; Hayato, Y.; Ishida, T.; Ishii, T.; Kobayashi, T.; Maruyama, T.; K. Nakamura; Obayashi, Y.; Oyama, Y.; Sakuda, M.; Yoshida, M

    2001-01-01

    The JHF-Kamioka neutrino project is a second generation long base line neutrino oscillation experiment that probes physics beyond the Standard Model by high precision measurements of the neutrino masses and mixing. A high intensity narrow band neutrino beam is produced by secondary pions created by a high intensity proton synchrotron at JHF (JAERI). The neutrino energy is tuned to the oscillation maximum at ~1 GeV for a baseline length of 295 km towards the world largest water Cerenkov detect...

  3. Pseudo-Dirac neutrinos as a potential complete solution to the neutrino oscillation puzzle

    Geiser, A

    1998-01-01

    A solution for the neutrino mass and mixing pattern is proposed which is compatible with all available experimental data on neutrino oscillations. This solution involves Majorana neutrinos of the pseudo-Dirac type, i.e. $m_{\\rm Majorana} \\ll m_{\\rm Dirac}$. The solar and atmospheric neutrino observations are mainly explained as $\

  4. Neutrino telescopes

    Carr, J

    2002-01-01

    This review presents the scientific objectives and status of Neutrino Telescope Projects. The science program of these projects covers: neutrino astronomy, dark matter searches and measurements of neutrino oscillations. The two neutrino telescopes in operation: AMANDA and BAIKAL will be described together with the ANTARES neutrino telescope being built in the Mediterranean. (18 refs).

  5. Evaluation of neutrino masses from $m_{\\beta\\beta}$ values

    Khrushchov, V V

    2008-01-01

    A neutrino mass matrix is considered under conditions of the CP invariance and the negligible reactor mixing $\\theta_{13}$ angle. Absolute mass values for three neutrinos are evaluated in normal and inverted hierarchy spectra on the ground of data for oscillation mixing neutrino parameters and effective neutrino mass entering into a probability of neutrinoless two beta decay $m_{\\beta\\beta}$ values.

  6. Review of neutrino mass measurements

    The current status of the experimental search for neutrino mass is reviewed, with emphasis on direct kinematic methods. New data on the /tau/ neutrino from the Argus collaboration have reduced the upper mass limit a factor of 2. The situation concerning the electron neutrino mass as measured in tritium beta decay is essentially unchanged from a year ago. Simpson and Hime report finding evidence for a 17-keV neutrino in the β decay of 35S. There may be evidence for neutrino mass and mixing in the SN1987a data. 62 refs., 4 figs

  7. Riddle of the Neutrino Mass

    Smirnov, A Yu

    2015-01-01

    We discuss some known approaches and results as well as few new ideas concerning origins and nature of neutrino mass. The key issues include (i) connections of neutrino and charged fermions masses, relation between masses and mixing, energy scale of new physics behind neutrino mass where possibilities spread from the Planck and GUT masses down to a sub-eV scale. The data hint two different new physics involved in generation of neutrino mass. Determination of the CP phase as well as mass hierarchy can play important role in identification of new physics. It may happen that sterile neutrinos provide the key to resolve the riddle.

  8. Neutrinos: summary of new results

    After a short presentation of the neutrino mass-mixing parameters, the core of the paper will be devoted to the recent experimental results from SNO, KamLAND and K2K. As a conclusion, I will discuss possible CP violation measurements with neutrinos. The paper is structured as follows: 1 Neutrino Oscillations Physics; 2 New results in solar neutrinos; 2.1 The SNO experiment; 2.2 The KamLAND experiment; 4 Opening the road toward a measurement of neutrino CP violation?

  9. Estimation of the systematic uncertainties of the measurement of the neutrino mixing angle θ13 related to the trigger system of the Double Chooz experiment

    The Double Chooz experiment, located in the Ardennes region next to the CHOOZ-B nuclear power plant, is a reactor antineutrino experiment to measure neutrino oscillations. It has been designed as precision experiment to measure the neutrino mixing angel θ13 with highest possible accuracy due to its small value close to zero. The electron antineutrino flux emitted by the reactor cores is measured by two identical neutrino detectors located at different distances from the reactor cores. Each detector consist of a 10.3 m3 target volume filled with liquid scintillator and surrounded by 390 photomultiplier tubes. The far detector is located 1.05 km away from the reactor cores to be most sensitive to oscillation effects. The unoscillated neutrino flux is measured by the near detector located 400 m away from the reactor cores. In order to reduce background events and other sources resulting in systematic uncertainties, special requirements have been demanded for all detector components and electronic systems. In this context, a most efficiently operating data acquisition system is essential. The subsystem responsible to start data storage for events of interest is the so called ''trigger system''. The design concept of the Double Chooz trigger system introduces two redundancy concepts in order to trigger the data acquisition in the most robust and efficient way: The trigger decision is based on a combination of an energy threshold and the number of active photomultiplier tubes (multiplicity condition). Secondly, the system is divided into two identical but independently operating subsystems for most robust operations of the full system. Additionally, the two subsystem provide the possibility to measure the efficiency of the system. Apart from generating the trigger signal for the data acquisition, the system provides an online event classification in order to adjust the amount of stored data for each event type. After one and a half year of data taking the Double Chooz

  10. Future Neutrino Oscillation Sensitivities for LBNE

    Bass, Matthew; Wilson, Robert J

    2013-01-01

    The primary goal of the Long-Baseline Neutrino Experiment (LBNE) is to measure the neutrino mixing matrix parameters. The design, optimized to search for CP violation and to determine the neutrino mass hierarchy, includes a large $\\mathcal{O}(10$ kt) Liquid Argon Time Projection Chamber (LAr TPC) at 1300 km downstream of a wide-band neutrino beam. A brief introduction to the neutrino mixing parameters will be followed by a discussion of sensitivity study analysis methods and a summary of the results for LBNE. The studies include comparisons with the Tokai-to-Kamioka (T2K) and NuMI Off-axis electron-neutrino Appearance (NO$\

  11. Reconciling sterile neutrinos with Big Bang nucleosynthesis

    We reexamine the big bang nucleosynthesis (BBN) bounds on the mixing of neutrinos with sterile species. These bounds depend on the assumption that the relic neutrino asymmetry Lν is very small. We show that for Lν large enough (greater than about 10endash5) the standard BBN bounds do not apply. We apply this result to the sterile neutrino solution to the atmospheric neutrino anomaly and show that for Lν approx-gt 7x10-5 it is consistent with BBN. The BBN bounds on sterile neutrinos mixing with electron neutrinos can also be weakened considerably. copyright 1995 The American Physical Society

  12. Oscillation Parameters with forthcoming Reactor Neutrino Experiments

    Lasserre, Thierry

    2010-01-01

    I review the status of the forthcoming reactor neutrino experiments that toe the cutting edge of neutrino oscillation research. Kilometer baseline oscillation experiments (Double Chooz, Daya Bay, and Reno) will soon play a relevant role providing clean information on the last undetermined neutrino mixing angle !13. A 50-70 km baseline reactor neutrino experiment could later provide the best sensitivity to the !12 mixing angle.

  13. Decay of reactor neutrinos

    We consider the decay of massive neutrinos which couple to electrons and are, therefore, produced in nuclear reactors. Lifetime limits for the γ and electron-positron decay modes of these neutrinos are deduced from the experimental limit on the singles count rate in the detector used to study neutrino oscillations at the Goesgen reactor. The dominantly coupled neutrinos are light, and their invariant-lifetime limit t/sup c.m.//m/sub ν/ is 1--3 sec/eV. The subdominantly coupled heavy neutrinos with mass 1--4 MeV could decay into electron-positron pairs. These pairs were not observed, and from the absence of such a signal we deduce restrictions on the corresponding mixing parameters

  14. Democratic Neutrino Paradigm

    Zhuridov, Dmitry

    2014-03-01

    I will introduce a democratic neutrino theory, which sets the absolute scale of the neutrino masses at about 0.03 eV, and has only one free parameter in contrast to 7 (9) free parameters in the conventional model of Dirac (Majorana) neutrino masses and mixing. Taking into account the incoherence and matter effects, this democratic theory agrees with the atmospheric and solar neutrino data. Moreover the results of the reactor neutrino experiments with the baselines around 100 m can be better explained. I will also discuss the predictions of this theory for low energy beta decays, magnetic moments, and neutrinoless double beta decays. Supported in part by the U.S. Department of Energy under contract DE-FG02-12ER41825.

  15. Neutrino physics

    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. (author)

  16. Neutrino Physics

    Gil-Botella, I

    2013-01-01

    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.

  17. Electron Neutrino Appearance in the MINOS Experiment

    MINOS is a long-baseline neutrino oscillation experiment tasked to make a precision measurement of the neutrino mixing parameters associated with the atmospheric neutrino mass splitting. Using a high powered neutrino beam from the Main Injector (NuMI) facility at Fermilab, it compares the neutrino energy spectrum for neutrino interactions observed in two large detectors located at Fermilab and in the Soudan mine in northern Minnesota at a distance of 735 km. We have recently presented muon-neutrino disappearance results after two years of data taking. Beyond those results there is the possibility that for a mixing angle related to electron-neutrino appearance in the vicinity of the current experimental limit, MINOS could make an initial measurement of this parameter. We present a method for particle identification of electron neutrinos and show several techniques being used to study the background contributions for this analysis in the non-oscillated data at the Near Detector

  18. Neutrino cosmology

    These lectures offer a self-contained review of the role of neutrinos in cosmology. The first part deals with the question 'What is a neutrino.' and describes in a historical context the theoretical ideas and experimental discoveries related to the different types of neutrinos and their properties. The basic differences between the Dirac neutrino and the Majorana neutrino are pointed out and the evidence for different neutrino 'flavours', neutrino mass, and neutrino oscillations is discussed. The second part summarizes current views on cosmology, particularly as they are affected by recent theoretical and experimental advances in high-energy particle physics. Finally, the close relationship between neutrino physics and cosmology is brought out in more detail, to show how cosmological constraints can limit the various theoretical possibilities for neutrinos and, more particularly, how increasing knowledge of neutrino properties can contribute to our understanding of the origin, history, and future of the Universe. The level is that of the beginning graduate student. (orig.)

  19. Present Aspects and Future Prospects of Neutrino Mass and Oscillation

    Ghosh, Monojit

    2016-01-01

    Neutrinos are neutral, spin-$\\frac{1}{2}$ particles which undergo only weak interactions. The experimentally observed phenomenon of neutrino oscillation establishes the fact that neutrinos are massive and there is mixing between different neutrino flavours. This constitutes the first unambiguous hint towards the physics Beyond Standard Model (BSM). In the BSM theories, the neutrino mass terms in the Lagrangian lead to the non-diagonal neutrino mass matrix in the flavour basis which depends on neutrino mass and mixing parameters. Thus knowledge of the neutrino oscillation parameters and understanding the underlying symmetries of the neutrino mass matrix are very important as they can give an insight to the new physics beyond Standard Model. Therefore the measurement of different oscillation parameters and studying the structure of the neutrino mass matrix are some of the main goals in neutrino physics at present. In this thesis we have studied the potential of present/future neutrino oscillation experiments an...

  20. Structure formation in a mixed dark matter model with decaying sterile neutrino: the 3.5 keV X-ray line and the Galactic substructure

    Harada, Akira; Yoshida, Naoki

    2016-01-01

    We perform a set of cosmological simulations of structure formation in a mixed dark matter (MDM) model. Our model is motivated by the recently identified $3.5\\,{\\rm keV}$ X-ray line that can be explained by the decay of non-resonantly produced sterile neutrinos, if they account for $10$-$60\\%$ of the dark matter in the Universe. The non-resonantly produced sterile neutrino has sizable free-streaming length and hence behaves effectively as warm dark matter (WDM). Assuming the rest of dark matter is composed of some stable and cold particles, i.e. cold dark matter (CDM), we follow the coevolution of the CDM and WDM density perturbations. Specifically, we consider the models with the warm component fraction of $r_{\\rm warm}=0.25$ and $0.5$. Our MDM model predicts that the comoving Jeans length at the matter-radiation equality is close to that of the thermally produced warm dark matter model with particle mass $m_{\\rm WDM}=2.4\\,{\\rm keV}$ but that the suppression in the fluctuation power spectrum is weaker. We pe...

  1. Geometric Mean Neutrino Mass Relation

    He, Xiao-Gang; Zee, A.

    Present experimental data from neutrino oscillations have provided much information about the neutrino mixing angles. Since neutrino oscillations only determine the mass squared differences Δ m2ij = m2i - m2j, the absolute values for neutrino masses mi, can not be determined using data just from oscillations. In this work we study implications on neutrino masses from a geometric mean mass relation m2 = √ {m1m_3} which enables one to determined the absolute masses of the neutrinos. We find that the central values of the three neutrino masses and their 2σ errors to be m1 = (1.58 ± 0.18)meV, m2 = (9.04 ± 0.42)meV, and m3 = (51.8 ± 3.5)meV. Implications for cosmological observation, beta decay and neutrinoless double beta decays are discussed.

  2. Neutrino Physics

    Lederman, L. M.

    1963-01-09

    The prediction and verification of the neutrino are reviewed, together with the V A theory for its interactions (particularly the difficulties with the apparent existence of two neutrinos and the high energy cross section). The Brookhaven experiment confirming the existence of two neutrinos and the cross section increase with momentum is then described, and future neutrino experiments are considered. (D.C.W.)

  3. Neutrino Masses and Flavor Oscillations

    Wang, Yifang

    2015-01-01

    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.

  4. Four-Neutrino Oscillation Solutions of the Solar Neutrino Problem

    Giunti, C; Peña-Garay, C

    2000-01-01

    We present an analysis of the neutrino oscillation solutions of the solar neutrino problem in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones. We perform a fit to the full data set corresponding to the 825-day Super-Kamiokande data sample as well as to Chlorine, GALLEX and SAGE and Kamiokande experiments. In our analysis we use all measured total event rates as well as all Super-Kamiokande data on the zenith angle dependence and the recoil electron energy spectrum. We consider both transitions via the Mikheyev-Smirnov-Wolfenstein (MSW) mechanism as well as oscillations in vacuum (just-so) and find the allowed solutions for different values of the additional mixing angles. This framework permits transitions into active or sterile neutrinos controlled by the additional parameter $\\cos^2(\\vartheta_{23}) \\cos^2(\\vartheta_{24})$ . We discuss the maximum allowed values of this additional mixing parameter for the different solutions.

  5. Neutrino Masses

    Weinheimer, Christian

    2013-01-01

    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 ...

  6. Probing the Origin of Neutrino Masses and Mixings via Doubly Charged Scalars: Complementarity of the Intensity and the Energy Frontiers

    Geib, Tanja; Merle, Alexander; No, Jose Miguel; Panizzi, Luca

    2015-01-01

    We discuss how the intensity and the energy frontiers provide complementary constraints within a minimal model of neutrino mass involving just one new field beyond the Standard Model at accessible energy, namely a doubly charged scalar $S^{++}$ and its antiparticle $S^{--}$. In particular we focus on the complementarity between high-energy LHC searches and low-energy probes such as lepton flavor violation. Our setting is a prime example of how high- and low-energy physics can cross-fertilize each other.

  7. Probing the origin of neutrino masses and mixings via doubly charged scalars: Complementarity of the intensity and the energy frontiers

    Geib, Tanja; King, Stephen F.; Merle, Alexander; No, Jose Miguel; Panizzi, Luca

    2016-04-01

    We discuss how the intensity and the energy frontiers provide complementary constraints within a minimal model of neutrino mass involving just one new field beyond the Standard Model at accessible energy, namely a doubly charged scalar S++ and its antiparticle S-- . In particular, we focus on the complementarity between high-energy LHC searches and low-energy probes such as lepton flavor violation. Our setting is a prime example of how high- and low-energy physics can cross-fertilize each other.

  8. Neutrino physics

    Harris, Deborah A.; /Fermilab

    2008-09-01

    The field of neutrino physics has expanded greatly in recent years with the discovery that neutrinos change flavor and therefore have mass. Although there are many neutrino physics results since the last DIS workshop, these proceedings concentrate on recent neutrino physics results that either add to or depend on the understanding of Deep Inelastic Scattering. They also describe the short and longer term future of neutrino DIS experiments.

  9. Embedding A4 into SU(3)xU(1) flavor symmetry: Large neutrino mixing and fermion mass hierarchy in SO(10) GUT

    Bazzocchi, F; Picariello, M; Torrente-Lujan, E

    2008-01-01

    We present a common explanation of the fermion mass hierarchy and the large lepton mixing angles in the context of a grand unified flavor and gauge theory (GUTF). Our starting point is a SU(3)xU(1) flavor symmetry and a SO(10) GUT, a basic ingredient of our theory which plays a major role is that two different breaking pattern of the flavor symmetry are at work. On one side, the dynamical breaking of SU(3)xU(1) flavor symmetry into U(2)xZ_3 explains why one family is much heavier than the others. On the other side, an explicit symmetry breaking of SU(3) into a discrete flavor symmetry leads to the observed tribimaximal mixing for the leptons. We write an explicit model where this discrete symmetry group is A4. Naturalness of the charged fermion mass hierarchy appears as a consequence of the continuous SU(3) flavor symmetry. Moreover, the same discrete A4-GUT invariant operators are the root of the large lepton mixing, small Cabibbo angle, and neutrino masses.

  10. Phenomenological consequences of singlet neutrinos

    In this paper, we study the phenomenology of right-handed neutrino isosinglets. We consider the general situation where the neutrino masses are not necessarily given by mD2/M, where mD and M are the Dirac and Majorana mass terms respectively. The consequent mixing between the light and heavy neutrinos is then not suppressed, and we treat it as an independent parameter in the analysis. It turns out that μ - e conversion is an important experiment in placing limits on the heavy mass scale (M) and the mixing. Mixings among light neutrinos are constrained by neutrinoless double beta decay, as well as by solar and atmospheric neutrino experiments. Detailed one-loop calculations for lepton number violating vertices are provided. (author). 26 refs., 8 figs

  11. Neutrino masses: from fantasy to facts

    Valle, J. W. F.

    Theory suggests the existence of neutrino masses, but little more. Facts are coming close to revealing our fantasy: solar- and atmospheric-neutrino data strongly indicate the need for neutrino conversions, while LSND provides an intriguing hint. The simplest ways to reconcile these data in terms of neutrino oscillations invoke a light sterile neutrino in addition to the three active ones. Out of the four neutrinos, two are maximally mixed and lie at the LSND scale, while the others are at the solar-mass scale. These schemes can be distinguished at neutral-current-sensitive solar- and atmospheric-neutrino experiments. I discuss the simplest theoretical scenarios, where the lightness of the sterile neutrino, the nearly maximal atmospheric-neutrino mixing and the generation of Δm {⊙/2} and Δm {atm/2} all follow naturally from the assumed lepton-number symmetry and its breaking. Although the most likely interpretation of the present data is in terms of neutrino-mass-induced oscillations, one still has room for alternative explanations, such as flavor-changing neutrino interactions, with no need for neutrino mass or mixing. Such flavor-violating transitions arise in theories with strictly massless neutrinos and may lead to other sizeable flavor non-conservation effects, such as μ → e + γ, μ - e conversion in nuclei, unaccompanied by neutrinoless double-beta decay.

  12. Neutrino mass models

    King, S. F.

    2004-02-01

    This is a review article about neutrino mass models, particularly see-saw models involving three active neutrinos that are capable of describing both the atmospheric neutrino oscillation data and the large mixing angle (LMA) MSW solar solution, which is now uniquely specified by recent data. We briefly review the current experimental status, show how to parametrize and construct the neutrino mixing matrix, and present the leading order neutrino Majorana mass matrices. We then introduce the see-saw mechanism and discuss a natural application of it to current data using the sequential dominance mechanism, which we compare with an early proposal for obtaining LMAs. We show how both the Standard Model and the Minimal Supersymmetric Standard Model may be extended to incorporate the see-saw mechanism and show how the latter case leads to the expectation of lepton flavour violation. The see-saw mechanism motivates models with additional symmetries such as unification and family symmetry models, and we tabulate some possible models before focusing on two particular examples based on SO(10) grand unification and either U(1) or SU(3) family symmetry as specific examples. This review contains extensive appendices that include techniques for analytically diagonalizing different types of mass matrices involving two LMAs and one small mixing angle, to leading order in the small mixing angle.

  13. Physics Potential of Solar Neutrino Experiments

    Balantekin, A. B.; Yuksel, H.

    2003-01-01

    We discuss the physics potential of the solar neutrino experiments i) To explore the parameter space of neutrino mass and mixings; ii) To probe the physics of the Sun; iii) To explore nuclear physics of the neutrino-target interactions. Examples are given for these three classes.

  14. Studies of Neutrino Oscillations at Reactors

    Boehm, Felix

    2000-01-01

    Experiments with reactor neutrinos continue to shed light on our understanding of neutrino oscillations. We review some of the early decisive experiments. We then turn to the recent long baseline oscillation experiments at Palo Verde and Chooz which are leading to the conclusion that the atmospheric neutrino anomaly if attributed to oscillations does not involve an appreciable mixing with the $\\bar\

  15. Solar models and solar neutrino oscillations

    Bahcall, John N.; Peña Garay, Carlos

    2004-01-01

    We provide a summary of the current knowledge, theoretical 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 doing new solar neutrino experiments and what we think may be learned from the future measurements.

  16. Neutrino spectrum from theory and experiments

    Anjan S Joshipura

    2000-01-01

    The observed deficits in the solar and atmospheric neutrino fluxes along with the accelerator results on neutrino oscillations significantly constrain possible mass and mixing patterns among neutrinos. We discuss possible patterns emerging from the experimental results and review theoretical attempts to understand them.

  17. Detecting sterile neutrinos with KATRIN like experiments

    Riis, Anna Sejersen; Hannestad, Steen

    2011-01-01

    A sterile neutrino with mass in the eV range, mixing with bar nue, is allowed and possibly even preferred by cosmology and oscillation experiments. If such eV-mass neutrinos exist they provide a much better target for direct detection in beta decay experiments than the active neutrinos which...

  18. Fermion masses and neutrino mixing in an SU(5)/sub GUT/ x SU(8)/sub ETC/ model

    We extend the SU(3) x SU(2) x U(1) model without scalars to SU(5)/sub GUT/ x SU(8)/sub ETC/. In our model, the mixing in the leptons is identical to that for the quarks, so that the Cabibbo angle determines the mixing of nu/sub e/ and nu/sub μ/. The quark masses and mixing angles are studied for two and three generations of quarks

  19. Atmospheric neutrinos and neutrino oscillations

    The results on the composition of atmospheric neutrinos interacting in underground detectors and on the rate of atmospheric muon neutrino interactions in the earth surrounding the detectors are reviewed. So far, systematic errors on the neutrino flux and on the electrons and muons neutrino interaction identifications are not yet reliable enough to prove that atmospheric neutrinos oscillate before being detected. (author) 22 refs., 5 figs

  20. Non-unitary neutrino propagation from neutrino decay

    Neutrino propagation in space-time is not constrained to be unitary if very light states – lighter than the active neutrinos – exist into which neutrinos may decay. If this is the case, neutrino flavor-change is governed by a handful of extra mixing and “oscillation” parameters, including new sources of CP-invariance violation. We compute the transition probabilities in the two- and three-flavor scenarios and discuss the different phenomenological consequences of the new physics. These are qualitatively different from other sources of unitarity violation discussed in the literature

  1. Non-unitary neutrino propagation from neutrino decay

    Jeffrey M. Berryman

    2015-03-01

    Full Text Available Neutrino propagation in space–time is not constrained to be unitary if very light states – lighter than the active neutrinos – exist into which neutrinos may decay. If this is the case, neutrino flavor-change is governed by a handful of extra mixing and “oscillation” parameters, including new sources of CP-invariance violation. We compute the transition probabilities in the two- and three-flavor scenarios and discuss the different phenomenological consequences of the new physics. These are qualitatively different from other sources of unitarity violation discussed in the literature.

  2. Sterile neutrino dark matter and core-collapse supernovae

    Mathews, Grant J; Hidaka, Jun; Kajino, Toshitaka

    2016-01-01

    We have explored the impact of sterile neutrino dark matter on core-collapse supernova explosions. We have included oscillations between electron neutrinos or mixed $\\mu,\\tau$ neutrinos and right-handed sterile neutrinos into a supernova model. We have chosen sterile neutrino masses and mixing angles that are consistent with sterile neutrino dark matter candidates as indicated by recent x-ray flux measurements. Using these simulations, we have explored the impact of sterile neutrinos on the core bounce and shock reheating. We find that, for ranges of sterile neutrino mass and mixing angle consistent with most dark matter constraints, the shock energy can be significantly enhanced and even a model that does not explode can be made to explode. In addition, we have found that the presence of a sterile neutrino may lead to detectable changes in the observed neutrino luminosities.

  3. Constraints on neutrino oscillations from big bang nucleosynthesis

    We discuss in detail the effect of neutrino oscillations in Big Bang nucleosynthesis between active and sterile neutrinos as well as between active and active neutrinos. We calculate the constraints on mixings between active and sterile neutrinos from the present observation of the primordial helium abundance and discuss the potential implications on various astrophysical and cosmological problems of such oscillations. In particular, we show that large-angle sterile neutrino mixing seems to be excluded as a MSW solution to the solar neutrino situation or a solution to the atmospheric neutrino mixing hinted at in some underground experiments. We show how, with this constraint, the next generation of solar neutrino experiments should be able to determine the resolution of the solar neutrino problem. It is also shown how sterile neutrinos remain a viable dark matter candidate

  4. Dark energy and neutrino model in SUSY

    We consider a Mass Varying Neutrinos (MaVaNs) model in supersymmetric theory. The model includes effects of supersymmetry breaking transmitted by the gravitational interaction from the hidden sector, in which supersymmetry was broken, to the dark energy sector. Then evolutions of the neutrino mass and the equation of state parameter of the dark energy are presented in the model. It is remarked that only the mass of a sterile neutrino is variable in the case of the vanishing mixing between the left-handed and a sterile neutrino on cosmological time scale. The finite mixing makes the mass of the left-handed neutrino variable. (author)

  5. Relic neutrino decoupling including flavour oscillations

    Mangano, Gianpiero [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II and INFN, Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Naples (Italy); Department of Physics, Syracuse University, Syracuse, NY 13244-1130 (United States); Miele, Gennaro [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II and INFN, Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Naples (Italy); Pastor, Sergio [Instituto de Fisica Corpuscular (CSIC-Universitat de Valencia), Ed. Institutos de Investigacion, Apdo. 22085, E-46071 Valencia (Spain)]. E-mail: pastor@ific.uv.es; Pinto, Teguayco [Instituto de Fisica Corpuscular (CSIC-Universitat de Valencia), Ed. Institutos de Investigacion, Apdo. 22085, E-46071 Valencia (Spain); Pisanti, Ofelia [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II and INFN, Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Naples (Italy); Serpico, Pasquale D. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, D-80805 Munich (Germany)

    2005-11-21

    In the early universe, neutrinos are slightly coupled when electron-positron pairs annihilate transferring their entropy to photons. This process originates non-thermal distortions on the neutrino spectra which depend on neutrino flavour, larger for {nu}{sub e} than for {nu}{sub {mu}} or {nu}{sub {tau}}. We study the effect of three-neutrino flavour oscillations on the process of neutrino decoupling by solving the momentum-dependent kinetic equations for the neutrino spectra. We find that oscillations do not essentially modify the total change in the neutrino energy density, giving N{sub eff}=3.046 in terms of the effective number of neutrinos, while the small effect over the production of primordial {sup 4}He is increased by O(20%), up to 2.1x10{sup -4}. These results are stable within the presently favoured region of neutrino mixing parameters.

  6. Neutrino self-interactions

    Hasenkamp, Jasper

    2016-03-01

    We propose a theory that equips the active neutrinos with interactions among themselves that are at least 3 orders of magnitude stronger than the weak interaction. We introduce an Abelian gauge group U (1 )X with vacuum expectation value vx≲O (100 MeV ) . An asymmetric mass matrix implements the active neutrinos as massless mass eigenstates carrying "effective" charges. To stabilize vx, supersymmetry breaking is mediated via loops to the additional sector with the only exception of xHiggs terms. No Standard Model interaction eigenstate carries U (1 )X charge. Thus, the dark photon's kinetic mixing is two-loop suppressed. With only simple and generic values of dimensionless parameters, our theory might explain the high-energy neutrino spectrum observed by IceCube including the PeV neutrinos. We comment on the imposing opportunity to incorporate a self-interacting dark matter candidate.

  7. Neutrino Self-Interactions

    Hasenkamp, Jasper

    2016-01-01

    We propose a theory that equips the active neutrinos with interactions among themselves that are at least three orders of magnitude stronger than the weak interaction. We introduce an Abelian gauge group $U(1)_x$ with vacuum expectation value $v_x \\lesssim \\mathcal{O}(100 \\textrm{ MeV})$. An asymmetric mass matrix implements the active neutrinos as massless mass eigenstates carrying "effective" charges. To stabilize $v_x$, supersymmetry breaking is mediated via loops to the additional sector with the only exception of xHiggs terms. No Standard Model interaction eigenstate carries $U(1)_x$ charge. Thus the dark photon's kinetic mixing is two-loop suppressed.With only simple and generic values of dimensionless parameters, our theory might explain the high-energy neutrino spectrum observed by IceCube including the PeV neutrinos. We comment on the imposing opportunity to incorporate a self-interacting dark matter candidate.

  8. Neutrino oscillations refitted

    Forero, D V; Valle, J W F

    2014-01-01

    Here we update our previous global fit of neutrino oscillations by including the recent results which have appeared since the Neutrino-2012 conference. These include the measurements of reactor anti-neutrino disappearance reported by Daya Bay and RENO, together with latest T2K and MINOS data including both disappearance and appearance channels. We also include the revised results from the third solar phase of Super-Kamiokande, SK-III, as well as new solar results from the fourth phase of Super-Kamiokande, SK-IV. We find that the preferred global determination of the atmospheric angle $\\theta_{23}$ is consistent with maximal mixing. We also determine the impact of the new data upon all the other neutrino oscillation parameters with emphasis on the increasing sensitivity to the CP phase, thanks to the interplay between accelerator and reactor data.

  9. Neutrino astrophysics

    A general overview of neutrino physics and astrophysics is given, starting with a historical account of the development of our understanding of neutrinos and how they helped to unravel the structure of the Standard Model. We discuss why it is so important to establish if neutrinos are massive and introduce the main scenarios to provide them a mass. The present bounds and the positive indications in favor of non-zero neutrino masses are discussed, including the recent results on atmospheric and solar neutrinos. The major role that neutrinos play in astrophysics and cosmology is illustrated. (author)

  10. Measurement of Atmospheric Neutrino Oscillations with the ANTARES Neutrino Telescope

    Adrian-Martinez, S; Albert, A; Andre, M; Anghinolfi, M; Anton, G; Anvar, S; Ardid, M; Astraatmadja, T; Aubert, J -J; Baret, B; Basa, S; Bertin, V; Biagi, S; Bigongiari, C; Bogazzi, C; Bou-Cabo, M; Bouhou, B; Bouwhuis, M C; Brunner, J; Busto, J; Capone, A; Carloganu, C; Carr, J; Cecchini, S; Charif, Z; Charvis, Ph; Chiarusi, T; Circella, M; Coniglione, R; Core, L; Costantini, H; Coyle, P; Creusot, A; Curtil, C; De Bonis, G; Decowski, M P; Dekeyser, I; Deschamps, A; Distefano, C; Donzaud, C; Dornic, D; Dorosti, Q; Drouhin, D; Eberl, T; Emanuele, U; Enzenhoefer, A; Ernenwein, J -P; Escoffier, S; Fehn, K; Fermani, P; Ferri, M; Ferry, S; Flaminio, V; Folger, F; Fritsch, U; Fuda, J -L; Galata, S; Gay, P; Geyer, K; Giacomelli, G; Giordano, V; Gleixner, A; Gomez-Gonzalez, J P; Graf, K; Guillard, G; Hallewell, G; Hamal, M; van Haren, H; Heijboer, A J; Hello, Y; Hernandez-Rey, J J; Herold, B; Hoessl, J; Hsu, C C; de Jong, M; Kadler, M; Kalekin, O; Kappes, A; Katz, U; Kavatsyuk, O; Kooijman, P; Kopper, C; Kouchner, A; Kreykenbohm, I; Kulikovskiy, V; Lahmann, R; Lambard, G; Larosa, G; Lattuada, D; Lefevre, D; Lim, G; Presti, D Lo; Loehner, H; Loucatos, S; Louis, F; Mangano, S; Marcelin, M; Margiotta, A; Martinez-Mora, J A; Meli, A; Montaruli, T; Morganti, M; Moscoso, L; Motz, H; Neff, M; Nezri, E; Palioselitis, D; Pavalas, G E; Payet, K; Petrovic, J; Piattelli, P; Popa, V; Pradier, T; Presani, E; Racca, C; Reed, C; Riccobene, G; Richardt, C; Richter, R; Riviere, C; Robert, A; Roensch, K; Rostovtsev, A; Ruiz-Rivas, J; Rujoiu, M; Russo, G V; Samtleben, D F E; Sanchez-Losa, A; Sapienza, P; Schmid, J; Schnabel, J; Schoeck, F; Schuller, J -P; Schuessler, F; Seitz, T; Shanidze, R; Simeone, F; Spies, A; Spurio, M; Steijger, J J M; Stolarczyk, Th; Taiuti, M; Tamburini, C; Trovato, A; Vallage, B; Vallee, C; Van Elewyck, V; Vecchi, M; Vernin, P; Visser, E; Wagner, S; Wijnker, G; Wilms, J; de Wolf, E; Yepes, H; Zaborov, D; Zornoza, J D; Zuniga, J

    2012-01-01

    The data taken with the ANTARES neutrino telescope from 2007 to 2010, a total live time of 863 days, are used to measure the oscillation parameters of atmospheric neutrinos. Muon tracks are reconstructed with energies as low as 20 GeV. Neutrino oscillations will cause a suppression of vertical upgoing muon neutrinos of such energies crossing the Earth. The parameters determining the oscillation of atmospheric neutrinos are extracted by fitting the event rate as a function of the ratio of the estimated neutrino energy and reconstructed flight path through the Earth. Measurement contours of the oscillation parameters in a two-flavour approximation are derived. Assuming maximum mixing, a mass difference of $\\Delta m_{32}^2=(3.1\\pm 0.9)\\cdot 10^{-3}$ eV$^2$ is obtained, in good agreement with the world average value.

  11. Measurement of atmospheric neutrino oscillations with the ANTARES neutrino telescope

    Adrian-Martinez, S. [Institut d' Investigacio per a la Gestio Integrada de les Zones Costaneres (IGIC), Universitat Politecnica de Valencia, C/ Paranimf 1, 46730 Gandia (Spain); Al Samarai, I. [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Albert, A. [GRPHE - Institut universitaire de technologie de Colmar, 34 rue du Grillenbreit, BP 50568, 68008 Colmar (France); Andre, M. [Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposicio, 08800 Vilanova i la Geltru, Barcelona (Spain); Anghinolfi, M. [INFN - Sezione di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Anton, G. [Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Anvar, S. [Direction des Sciences de la Matiere, Institut de recherche sur les lois fondamentales de l' Univers, Service d' Electronique des Detecteurs et d' Informatique, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France); Ardid, M. [Institut d' Investigacio per a la Gestio Integrada de les Zones Costaneres (IGIC), Universitat Politecnica de Valencia, C/ Paranimf 1, 46730 Gandia (Spain); Astraatmadja, T. [Nikhef, Science Park, Amsterdam (Netherlands); Aubert, J.-J. [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); and others

    2012-08-14

    The data taken with the ANTARES neutrino telescope from 2007 to 2010, a total live time of 863 days, are used to measure the oscillation parameters of atmospheric neutrinos. Muon tracks are reconstructed with energies as low as 20 GeV. Neutrino oscillations will cause a suppression of vertical upgoing muon neutrinos of such energies crossing the Earth. The parameters determining the oscillation of atmospheric neutrinos are extracted by fitting the event rate as a function of the ratio of the estimated neutrino energy and reconstructed flight path through the Earth. Measurement contours of the oscillation parameters in a two-flavour approximation are derived. Assuming maximal mixing, a mass difference of {Delta}m{sub 32}{sup 2}=(3.1{+-}0.9) Dot-Operator 10{sup -3} eV{sup 2} is obtained, in good agreement with the world average value.

  12. Measurement of atmospheric neutrino oscillations with the ANTARES neutrino telescope

    The data taken with the ANTARES neutrino telescope from 2007 to 2010, a total live time of 863 days, are used to measure the oscillation parameters of atmospheric neutrinos. Muon tracks are reconstructed with energies as low as 20 GeV. Neutrino oscillations will cause a suppression of vertical upgoing muon neutrinos of such energies crossing the Earth. The parameters determining the oscillation of atmospheric neutrinos are extracted by fitting the event rate as a function of the ratio of the estimated neutrino energy and reconstructed flight path through the Earth. Measurement contours of the oscillation parameters in a two-flavour approximation are derived. Assuming maximal mixing, a mass difference of Δm322=(3.1±0.9)⋅10-3 eV2 is obtained, in good agreement with the world average value.

  13. Dependence of the leptonic decays of H{sup ±} on the neutrino mixing angles θ{sub 13} and θ{sub 23} in models with neutrinophilic charged scalars

    Akeroyd, A.G., E-mail: a.g.akeroyd@soton.ac.uk [School of Physics and Astronomy, University of Southampton Highfield, Southampton SO17 1BJ (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Moretti, S., E-mail: S.Moretti@soton.ac.uk [School of Physics and Astronomy, University of Southampton Highfield, Southampton SO17 1BJ (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Sugiyama, Hiroaki, E-mail: sugiyama@cc.kyoto-su.ac.jp [Maskawa Institute for Science and Culture, Kyoto Sangyo University, Kyoto 603-8555 (Japan)

    2014-01-20

    In the Higgs Triplet Model and the neutrinophilic Two-Higgs-Doublet Model the observed neutrinos obtain mass from a vacuum expectation value which is much smaller than the vacuum expectation value of the Higgs boson in the Standard Model. Both models contain a singly charged Higgs boson (H{sup ±}) whose Yukawa coupling is directly related to the neutrino mass (i.e. a “neutrinophilic charged Higgs”). The partial decay widths of H{sup ±} into a charged lepton and a neutrino (H{sup ±}→ℓ{sup ±}ν) depend identically on the neutrino masses and mixings in the two models. We quantify the impact of the recent measurement of sin{sup 2}2θ{sub 13}, which plays a crucial role in determining the magnitude of the branching ratio of H{sup ±}→e{sup ±}ν for the case of a normal neutrino mass ordering if the lightest neutrino mass m{sub 0}<10{sup −3} eV. We also discuss the sizeable dependence of H{sup ±}→μ{sup ±}ν and H{sup ±}→τ{sup ±}ν on sin{sup 2}θ{sub 23}, which would enable information to be obtained on sin{sup 2}θ{sub 23} and the sign of Δm{sub 31}{sup 2} if these decays are measured. Such information would help neutrino oscillation experiments to determine the CP-violating phase δ.

  14. Neutrino masses

    Buccella, F

    2004-01-01

    By requiring the lower limit for the lightest right-handed neutrino mass, obtained in the baryogenesis from leptogenesis scenario, and a Dirac neutrino mass matrix similar to the up-quark mass matrix we predict small values for the $\

  15. Neutrino astronomy

    In recent years, there has been considerable discussion on the field called neutrino astronomy which represents exciting prospect in that it deals with the radiations which are distinct from electromagnetic spectra. Because of the unique, enormously long interaction mean free path of neutrinos, this field can in principle give extremely valuable complementary information about the universe, in particular about the conditions in the core of the sun and the energy balance and extent of the galaxy. Remarkable difference is observed when outlining of the development of neutrino astronomy is attempted in a manner similar to that for radio astronomy. The development on solar neutrinos, calculation of solar neutrino flux, solar neutrino search experiments, efforts to resolve the discrepancy between theory and experiment concerning the neutrinos from the sun, chemistry consideration, nuclear physics problems, astrophysical calculation, neutrino physics and other physical accomplishments are reviewed in the report. (Iwase, T.)

  16. Neutrino Astrophysics

    Haxton, W. C.

    2000-01-01

    A general overview of neutrino physics and astrophysics is given, starting with a historical account of the development of our understanding of neutrinos and how they helped to unravel the structure of the Standard Model. We discuss why it is so important to establish if neutrinos are massive and introduce the main scenarios to provide them a mass. The present bounds and the positive indications in favor of non-zero neutrino masses are discussed, including the recent results on atmospheric an...

  17. Neutrino Physics

    Romanino, Andrea

    2012-01-01

    These lectures aim at providing a pedagogical overview of neutrino physics. We will mostly deal with standard neutrinos, the ones that are part of the Standard Model of particle physics, and with their standard dynamics, which is enough to understand in a coherent picture most of the rich data available. After introducing the basic theoretical framework, we will illustrate the experimental determination of the neutrino parameters and their theoretical implications, in particular for the origin of neutrino masses.

  18. A Novel Approach In The Detection Of Muon Neutrino To Tau Neutrino Oscillation From Extragalactic Neutrinos

    Iyer, S R

    2001-01-01

    A novel approach is proposed for studying the νμ → ν τ oscillation and detection of extragalactic neutrinos. Active Galactic Nuclei (AGN), Gamma Ray Bursters (GRB) and Topological Defects are believed to be sources of ultrahigh energy νμ and ντ. These astrophysical sources provide a long baseline of 100Mpc, or more, for possible detection of νμ → ντ oscillation with mixing parameter Δm2 down to 10 −17 eV2, many orders of magnitude below the current accelerator experiments. The propagation characteristics of upward going muon and tau neutrinos is studied to show that high energy tau neutrinos cascade down in energy as they propagate through the Earth, producing an enhancement of the incoming tau neutrino flux in the low energy region. By contrast, high energy muon neutrinos get attenuated as they traverse the Earth. It is observed that the relative steepness of the incoming neutrino flux...

  19. Entanglement in neutrino oscillations

    Flavor oscillations in elementary particle physics are related to multimode entanglement of single-particle states. We show that mode entanglement can be expressed in terms of flavor transition probabilities, and therefore that single-particle entangled states acquire a precise operational characterization in the context of particle mixing. We treat in detail the physically relevant cases of two- and three-flavor neutrino oscillations, including the effective measure of CP violation. We discuss experimental schemes for the transfer of the quantum information encoded in single-neutrino states to spatially delocalized two-flavor charged-lepton states, thus showing, at least in principle, that single-particle entangled states of neutrino mixing are legitimate physical resources for quantum information tasks. (authors)

  20. Entanglement in neutrino oscillations

    Blasone, M.; Dell' Anno, F.; De Siena, S.; Illuminati, F. [Universita degli Studi di Salerno Via Ponte don Melillon, Dipt. di Matematica e Informatica, Fisciano SA (Italy); INFN Sezione di Napoli, Gruppo collegato di Salerno - Baronissi SA (Italy); Dell' Anno, F.; De Siena, S.; Illuminati, F. [CNR-INFM Coherentia - Napoli (Italy); Blasone, M. [ISI Foundation for Scientific Interchange, Torino (Italy)

    2009-03-15

    Flavor oscillations in elementary particle physics are related to multimode entanglement of single-particle states. We show that mode entanglement can be expressed in terms of flavor transition probabilities, and therefore that single-particle entangled states acquire a precise operational characterization in the context of particle mixing. We treat in detail the physically relevant cases of two- and three-flavor neutrino oscillations, including the effective measure of CP violation. We discuss experimental schemes for the transfer of the quantum information encoded in single-neutrino states to spatially delocalized two-flavor charged-lepton states, thus showing, at least in principle, that single-particle entangled states of neutrino mixing are legitimate physical resources for quantum information tasks. (authors)

  1. Neutrino properties

    Valle, José W F

    1996-01-01

    A brief sketch is made of the present observational status of neutrino properties, with emphasis on the hints from solar and atmospheric neutrinos, as well as cosmological data on the amplitude of primordial density fluctuations. Implications of neutrino mass in particle accelerators, astrophysics and cosmology are discussed.

  2. Neutrino Radar

    Panigrahi, P K

    2002-01-01

    We point out that with improving our present knowledge of experimental neutrino physics it will be possible to locate nuclear powered vehicles like submarines, aircraft carriers and UFOs and detect nuclear testing. Since neutrinos cannot be shielded, it will not be possible to escape these detection. In these detectors it will also be possible to perform neutrino oscillation experiments during any nuclear testing.

  3. Naturally perturbed S$_3$ neutrinos

    Jora, Renata; Shahid, M Naeem

    2012-01-01

    We simplify and extend our previous model for the masses and mixing matrix of three Majorana neutrinos based on permutation symmetry $S_3$ and the perturbations which violate this symmetry. The perturbations are arranged such that we get the smaller solar neutrinos mass difference at second order. We work out the corrections to the tribimaximal mixing matrix with the non-zero value for $s_{13}$ and the conventional CP-violating phase. It is shown that the results of the model are comparable with the global analysis of neutrino oscillation data.

  4. Measuring Neutrino Oscillations with Nuclear Reactors

    McKeown, R.D.

    2007-01-01

    Since the first direct observations of antineutrino events by Reines and Cowan in the 1950's [1], nuclear reactors have been an important tool in the study of neutrino properties. More recently, the study of neutrino oscillations has been a very active area of research. The pioneering observation of oscillations by the KamLAND experiment has provided crucial information on the neutrino mixing matrix. New experiments to study the remaining unknown mixing angle are currently under development. ...

  5. Phenomenological Consequences of Heavy Right Handed Neutrinos

    Rayyan, Saifuddin Ramadan

    2007-01-01

    The discovery of neutrino mixing provides the possibility of a non vanishing CP violating phase in the neutrino mixing matrix. CP violation in the leptonic sector can be large enough to explain the matter-antimatter asymmetry in the universe. An indirect probe of CP violation is the experimental measurement of Electric Dipole Moment (EDM). CP violation has been discovered in the quark sector,but it contributes to lepton EDM at the 3-loop level. Neutrino masses can...

  6. Leptogenesis with Almost Degenerate Majorana Neutrinos

    Fujii, M; Yanagida, T; Fujii, Masaaki

    2002-01-01

    We investigate the leptogenesis with almost degenerate neutrinos, in the framework of democratic mass matrix, which naturally explains the large mixing angles for neutrino oscillations as well as quark masses and mixing matrix. We find that the baryon asymmetry in the present universe is explained via the decays of right-handed neutrinos produced nonthermally by the inflaton decay. The model predicts neutrinoless double beta decays accessible in near future experiments.

  7. Supernova Neutrino Nucleosynthesis of Light Elements with Neutrino Oscillations

    Yoshida, T; Yokomakura, H; Kimura, K; Takamura, A; Hartmann, D H

    2006-01-01

    Light element synthesis in supernovae through neutrino-nucleus interactions, i.e., the nu-process, is affected by neutrino oscillations in the supernova environment. There is a resonance of 13-mixing in the O/C layer, which increases the rates of charged-current nu-process reactions in the outer He-rich layer. The yields of 7Li and 11B increase by about a factor of 1.9 and 1.3, respectively, for a normal mass hierarchy and an adiabatic 13-mixing resonance, compared to those without neutrino oscillations. In the case of an inverted mass hierarchy and a non-adiabatic 13-mixing resonance, the increase in the 7Li and 11B yields is much smaller. Observations of the 7Li/11B ratio in stars showing signs of supernova enrichment could thus provide a unique test of neutrino oscillations and constrain their parameters and the mass hierarchy.

  8. Neutrino spin-flavor oscillations derived from the mass basis

    Fabbricatore, Riccardo; Studenikin, Alexander

    2016-01-01

    We consider neutrino mixing and oscillations in presence of an arbitrary constant magnetic field with nonzero transversal $B_{\\perp}$ and longitudinal $B_{\\parallel}$ components with respect to the direction of neutrino propagation. The electromagnetic interaction of neutrinos is determined by diagonal and transition neutrino magnetic moments that are introduced for the neutrino mass states. Explicit expressions for the effective neutrino diagonal and transition magnetic moments for the flavor basis in terms of these values for the mass states are obtained. The effective evolution Hamiltonian for the flavor neutrino and the corresponding oscillation probability are derived. The role of the longitudinal magnetic field component is examined. In particular, it is shown that: 1) $B_{\\parallel}$ coupled to the corresponding magnetic moments shifts the neutrino energy, and 2) in case of nonvanishing neutrino transition magnetic moments $B_{\\parallel}$ produces an additional mixing between neutrino states, both in t...

  9. Sterile neutrino oscillations in core-collapse supernova simulations

    Warren, MacKenzie L; Mathews, Grant; Hidaka, Jun; Kajino, Toshitaka

    2014-01-01

    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.

  10. Solar neutrinos

    The problem with solar neutrinos is that there seem to be too few of them, at least near the top end of the spectrum, since the 37Cl detector finds only about 35% of the standard predicted flux. Various kinds of explanation have been offered: (a) the standard solar model is wrong, (b) neutrinos decay, (c) neutrinos have magnetic moments, (d) neutrinos oscillate. The paper surveys developments in each of these areas, especially the possible enhancement of neutrino oscillations by matter effects and adiabatic level crossing. The prospects for further independent experiments are also discussed. (author)

  11. A precise measurement of the electroweak mixing angle in the scattering of high energy neutrinos of an iron target

    A precise measurement of the neutral to charged current interaction ratio has been performed in 1984 by the CDHS collaboration (CERN-Dortmund-Heidelberg-Saclay). The value of the electroweak mixing angle has been extracted using a method proposed by Llewellyn-Smith where the quark parton model enters only through small corrections

  12. Solar neutrinos and neutrino physics

    Maltoni, Michele; Smirnov, Alexei Yu.

    2016-04-01

    Solar neutrino studies triggered and largely motivated the major developments in neutrino physics in the last 50 years. The theory of neutrino propagation in different media with matter and fields has been elaborated. It includes oscillations in vacuum and matter, resonance flavor conversion and resonance oscillations, spin and spin-flavor precession, etc. LMA MSW has been established as the true solution of the solar neutrino problem. Parameters θ_{12} and Δ m 2 21 have been measured; θ_{13} extracted from the solar data is in agreement with results from reactor experiments. Solar neutrino studies provide a sensitive way to test theory of neutrino oscillations and conversion. Characterized by long baseline, huge fluxes and low energies they are a powerful set-up to search for new physics beyond the standard 3 ν paradigm: new neutrino states, sterile neutrinos, non-standard neutrino interactions, effects of violation of fundamental symmetries, new dynamics of neutrino propagation, probes of space and time. These searches allow us to get stringent, and in some cases unique bounds on new physics. We summarize the results on physics of propagation, neutrino properties and physics beyond the standard model obtained from studies of solar neutrinos.

  13. JUNO. Determination of the neutrino mass hierarchy using reactor neutrinos

    The Jiangmen Underground Neutrino Observatory (JUNO) is a medium-baseline reactor neutrino experiment located in China. Its aim is to determine the neutrino mass hierarchy at more than 3 sigma significance after six years of data taking by using a 20kt liquid scintillator detector. To achieve this goal, an energy resolution of less than 3%/√(E) is necessary, creating strict requirements on the detector design and the liquid scintillator. Moreover, JUNO will be the only experiment in the near future able to measure the solar mixing parameters with a precision of better than 1%. This is at the same level as our current knowledge on flavour mixing in the quark sector, marking an important milestone of neutrino physics. In addition, supernova neutrinos, geo-neutrinos, sterile neutrinos as well as solar and atmospheric neutrinos can be studied. JUNO was approved in 2013 and the construction of the underground facility started early this year. In this talk the status of the experiment and its prospects is discussed.

  14. JUNO. Determination of the neutrino mass hierarchy using reactor neutrinos

    Wonsak, Bjoern [Hamburg University, Inst. Exp. Phys., Hamburg (Germany)

    2015-07-01

    The Jiangmen Underground Neutrino Observatory (JUNO) is a medium-baseline reactor neutrino experiment located in China. Its aim is to determine the neutrino mass hierarchy at more than 3 sigma significance after six years of data taking by using a 20kt liquid scintillator detector. To achieve this goal, an energy resolution of less than 3%/√(E) is necessary, creating strict requirements on the detector design and the liquid scintillator. Moreover, JUNO will be the only experiment in the near future able to measure the solar mixing parameters with a precision of better than 1%. This is at the same level as our current knowledge on flavour mixing in the quark sector, marking an important milestone of neutrino physics. In addition, supernova neutrinos, geo-neutrinos, sterile neutrinos as well as solar and atmospheric neutrinos can be studied. JUNO was approved in 2013 and the construction of the underground facility started early this year. In this talk the status of the experiment and its prospects is discussed.

  15. Neutrino mass spectrum with υμ → υs oscillations of atmospheric neutrinos

    We consider the ''standard'' spectrum of the active neutrinos (characterized by strong mass hierarchy and small mixing) with additional sterile, υs. The sterile neutrino mixes strongly with the muon neutrino, so that υμ ↔ υs oscillations solve the atmospheric neutrino problem. We show that the parametric enhancement of the υμ ↔ υs oscillations occurs for the high energy atmospheric neutrinos which cross the core of the Earth. This can be relevant for the anomaly observed by the MACRO experiment. Solar neutrinos are converted both to υμ and υs. The heaviest neutrino (approx. υτ) may compose the hot dark matter of the Universe. Phenomenology of this scenario is elaborated and crucial experimental signatures are identified. We also discuss properties of the underlying neutrino mass matrix. (author)

  16. Neutrino Factory

    Bogomilov, M; Tsenov, R; Dracos, M; Bonesini, M; Palladino, V; Tortora, L; Mori, Y; Planche, T; Lagrange, J  B; Kuno, Y; Benedetto, E; Efthymiopoulos, I; Garoby, R; Gilardoini, S; Martini, M; Wildner, E; Prior, G; Blondel, A; Karadzhow, Y; Ellis, M; Kyberd, P; Bayes, R; Laing, A; Soler, F  J  P; Alekou, A; Apollonio, M; Aslaninejad, M; Bontoiu, C; Jenner, L  J; Kurup, A; Long, K; Pasternak, J; Zarrebini, A; Poslimski, J; Blackmore, V; Cobb, J; Tunnell, C; Andreopoulos, C; Bennett, J  R  J; Brooks, S; Caretta, O; Davenne, T; Densham, C; Edgecock, T  R; Fitton, M; Kelliher, D; Loveridge, P; McFarland, A; Machida, S; Prior, C; Rees, G; Rogers, C; Rooney, M; Thomason, J; Wilcox, D; Booth, C; Skoro, G; Back, J  J; Harrison, P; Berg, J  S; Fernow, R; Gallardo, J  C; Gupta, R; Kirk, H; Simos, N; Stratakis, D; Souchlas, N; Witte, H; Bross, A; Geer, S; Johnstone, C; Mokhov, N; Neuffer, D; Popovic, M; Strait, J; Striganov, S; Morfín, J  G; Wands, R; Snopok, P; Bogacz, S  A; Morozov, V; Roblin, Y; Cline, D; Ding, X; Bromberg, C; Hart, T; Abrams, R  J; Ankenbrandt, C  M; Beard, K  B; Cummings, M  A  C; Flanagan, G; Johnson, R  P; Roberts, T  J; Yoshikawa, C  Y; Graves, V  B; McDonald, K  T; Coney, L; Hanson, G

    2014-01-01

    The properties of the neutrino provide a unique window on physics beyond that described by the standard model. The study of subleading effects in neutrino oscillations, and the race to discover CP-invariance violation in the lepton sector, has begun with the recent discovery that $\\theta_{13} > 0$. The measured value of $\\theta_{13}$ is large, emphasizing the need for a facility at which the systematic uncertainties can be reduced to the percent level. The neutrino factory, in which intense neutrino beams are produced from the decay of muons, has been shown to outperform all realistic alternatives and to be capable of making measurements of the requisite precision. Its unique discovery potential arises from the fact that only at the neutrino factory is it practical to produce high-energy electron (anti)neutrino beams of the required intensity. This paper presents the conceptual design of the neutrino factory accelerator facility developed by the European Commission Framework Programme 7 EURO$\

  17. Expectation values of flavor-neutrino numbers with respect to neutrino-source hadron states --Neutrino oscillations and decay probabilities--

    Fujii, Kanji

    2014-01-01

    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.

  18. A review of the impact of sterile neutrino dark matter on core-collapse supernovae

    Warren, MacKenzie; Meixner, Matthew; Hidaka, Jun; Kajino, Toshitaka

    2016-01-01

    We review the impact of sterile neutrino dark matter on core-collapse supernova explosions. We summarize various oscillations between electron neutrinos or mixed $\\mu-\\tau$ neutrinos and right-handed sterile neutrinos that have been studied within a supernova model. In particular, we consider sterile neutrino masses and mixing angles that are consistent with sterile neutrino dark matter candidates as indicated by recent x-ray flux measurements. We review how mixing between electron neutrinos and sterile neutrinos can significantly enhance the shock energy, and even a model that does not explode can be made to explode by this mechanism. However, the mixing between $\\mu-\\tau$ neutrinos and sterile neutrinos does not significantly alter the explosion and has little effect on the neutrino luminosities at early times.

  19. Neutrino masses

    Weinheimer, Christian [Institut fuer Kernphysik, Westfaelische Wilhelms-Universitaet Muenster, Wilhelm-Klemm-Str. 9, D-48149 Muenster (Germany); Zuber, Kai [Institut fuer Kern- und Teilchenphysik, Technische Universitaet Dresden, Zellescher Weg 19, D-01069 Dresden (Germany)

    2013-09-15

    The various experiments on neutrino oscillation evidence that neutrinos have indeed non-zero masses but cannot provide 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 using different techniques are being constructed, commissioned, or are even running, which aim for a sensitivity on the neutrino mass of O(100) meV. The principal methods and these experiments are discussed in this short review. (copyright 2013 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Liquid argon neutrino detectors

    Battistoni, G

    2001-01-01

    The liquid argon imaging technique, as proposed for the ICARUS detector, offers the possibility to perform complementary and simultaneous measurements of neutrinos, as those of CERN to Gran Sasso beam (CNGS) and those from cosmic ray events. For the currently allowed values of the Super-Kamiokande results, the combination of both CNGS and atmospheric data will provide a precise determination of the oscillation parameters. Since one can observe and unambiguously identify nu /sub e/, nu /sub mu / and nu /sub tau / components, this technology allows to explore the full (3*3) mixing matrix. The same class of detector can be proposed for high precision measurements at a neutrino factory. (3 refs).

  1. Neutrino sunshine

    Full text: On 10 June 1992, at the Neutrino 92 meeting in Grenada, Spain, Till Kirsten of Heidelberg's Max Planck Institute reported that neutrinos from sunshine had been seen. Most of the energy pumped out by the Sun comes from the fusion of protons into alpha particles, a process which also liberates neutrinos. While it takes about a million years for radiant energy formed in the deep interior of the Sun to fight its way to the surface, the highly penetrating neutrinos emerge almost immediately. It was in 1970 that Ray Davis and his team began taking data with a tank containing 615 tons of perchloroethylene (dry cleaning fluid) 1500 metres underground in the Homestake gold mine, South Dakota. The observed signal is consistently smaller than what is expected. This 'solar neutrino problem' was confirmed by the Kamioka mine experiment in Japan, looking at the Cherenkov light released by neutrino interactions in some 700 tons of water. However these experiments are only sensitive to a tiny high energy tail of the solar neutrino spectrum, and to understand what is going on needs measurements of the primary neutrinos from proton fusion. To get at these neutrinos, two large new detectors, using gallium and sensitive to these lower energy particles, have been built and commissioned in the past few years. The detectors are SAGE ('Soviet' American Gallium Experiment) in the Baksan Neutrino Observatory in the Caucasus, and Gallex, a team from France, Germany, Israel, Italy and the US in the Italian Gran Sasso underground Laboratory. At Grenada, Kirsten reported unmistakable signs of solar neutrinos of proton origin recorded in Gallex. SAGE and Gallex do not yet have enough data to unambiguously fix the level of primary solar neutrinos reaching the Earth, and the interpretation of the interim results tends to be subjective. However after 23 years of conditioning through watching the solar neutrinos' high energy tail, the prospect of a neutrino

  2. Quantum numbers of heavy neutrinos, tri-bi-maximal mixing through double seesaw with permutation symmetry, and comment on θsol + θc ≅ π/4

    Using the family symmetry, in the neutrino mass matrix we remove the Yukawa coupling (arising in the Dirac type mass between the heavy neutrinos and light lepton doublets) dependence in the double seesaw mechanism so that it is directly proportional to the mass matrix m(nn) of heavy Majorana neutrinos. The family symmetry is supposed to be broken spontaneously at high energy scale so that the neutrino mass matrix is given by the family symmetry at high energy scale. With the permutation symmetry S3, we note a variety of possible mass hierarchies arising distinctly in neutrinos, charged leptons, Qem = -1/3 quarks, and Qem = 2/3 quarks. Distinguishing these hierarchies, we obtain a relation between the CKM angles and the MNS angles. Finally, we comment on the approximate relation θsol + θc ≅ π/4

  3. Quasi-Degenerate Neutrino Masses with Normal and Inverted Hierarchy

    Francis, Ng K

    2012-01-01

    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{\

  4. Physics prospects of future neutrino oscillation experiments in Asia

    Hagiwara, Kaoru

    2004-01-01

    The three neutrino model has 9 physical parameters, 3 neutrino masses, 3 mixing angles and 3 CP violating phases. Among them, neutrino oscillation experiments can probe 6 parameters: 2 mass squared differences, 3 mixing angles, and 1 CP phase. The experiments performed so far determined the magnitudes of the two mass squared differences, the sign of the smaller mass squared difference, the magnitudes of two of the three mixing angles, and the upper bound on the third mixing angle. The sign of...

  5. Solar Neutrinos

    Davis, R. Jr.; Harmer, D. S.

    1964-12-01

    The prospect of studying the solar energy generation process directly by observing the solar neutrino radiation has been discussed for many years. The main difficulty with this approach is that the sun emits predominantly low energy neutrinos, and detectors for observing low fluxes of low energy neutrinos have not been developed. However, experimental techniques have been developed for observing neutrinos, and one can foresee that in the near future these techniques will be improved sufficiently in sensitivity to observe solar neutrinos. At the present several experiments are being designed and hopefully will be operating in the next year or so. We will discuss an experiment based upon a neutrino capture reaction that is the inverse of the electron-capture radioactive decay of argon-37. The method depends upon exposing a large volume of a chlorine compound, removing the radioactive argon-37 and observing the characteristic decay in a small low-level counter.

  6. Lepton physics versus neutrino mass

    The relationship between the strength of lepton flavour violating processes and the magnitude of the neutrino mass is rather model dependent. I review this question within different neutrino mixing models including superstring inspired models. Processes such as μ→e+γ, μ→3e, μ-e conversion in nuclei, etc. as well as lepton flavour violating Z0 decays can occur even if the physical neutrinos are strictly massless. As a result, the corresponding rates are unconstrained by bounds on the neutrino mass that follow from laboratory, astrophysics and cosmology and can therefore be large. Leptonic CP violation may also occur even when the physical neutrinos are strictly massless. (orig.)

  7. The Jiangmen Underground Neutrino Observatory

    Grassi, Marco

    2016-01-01

    The Jiangmen Underground Neutrino Observatory (JUNO) is a large and high precision liquid scintillator detector under construction in the south of China. With its 20 kt target mass, it aims to achieve an unprecedented 3% energy resolution at 1 MeV. Its main goal is to study the disappearance of reactor antineutrino to determine the neutrino mass ordering, and to precisely measure the mixing parameters $\\theta_{12}$, $\\Delta m^2_{12}$, and $\\Delta m ^2_{ee}$. It also aims to detect neutrinos emitted from radioactive processes taking place within the inner layers of the Earth (geonutrinos), as well as neutrinos produced during rare supernova bursts. Neutrinos emitted in solar nuclear reactions could also be observed, if stringent radiopurity requirements on the scintillator are met. This manuscript provides some highlights of JUNO's Physics Programme, and describes the detector design, as well as the ongoing detector R&D.

  8. Atmospheric Neutrinos

    Gaisser, Thomas K

    2016-01-01

    In view of the observation by IceCube of high-energy astrophysical neutrinos, it is important to quantify the uncertainty in the background of atmospheric neutrinos. There are two sources of uncertainty, the imperfect knowledge of the spectrum and composition of the primary cosmic rays that produce the neutrinos and the limited understanding of hadron production, including charm, at high energy. This paper is an overview of both aspects.

  9. Tritium neutrino mass experiments

    The current status of the experimental search for neutrino mass is reviewed, with emphasis on direct kinematic methods, such as the beta decay of tritium. The situation concerning the electron neutrino mass as measured in tritium beta decay is essentially unchanged from a year ago, although a great deal of experimental work is in progress. The ITEP group continues to find evidence for a nonzero mass, now slightly revised to 26(5) eV. After correcting for recently discovered errors in the energy loss distribution and source thickness, however, the Z/umlt u/rich group still claims and upper limit of 18 eV. There may be evidence for neutrino mass and mixing in the SN1987a data, in the same range suggested by the ITEP experiment. 42 refs., 3 figs

  10. Atmospheric neutrinos and discovery of neutrino oscillations

    Neutrino oscillation was discovered through studies of neutrinos produced by cosmic-ray interactions in the atmosphere. These neutrinos are called atmospheric neutrinos. They are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith-angle and energy dependent deficit of muon-neutrino events. Neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. Neutrino oscillations imply that neutrinos have small but non-zero masses. The small neutrino masses have profound implications to our understanding of elementary particle physics and the Universe. This article discusses the experimental discovery of neutrino oscillations. (author)

  11. Neutrinos Confronting Large Extra Dimensions

    Maalampi, J; Vilja, I

    2001-01-01

    We study neutrino physics in a model with one large extra dimension. We assume the existence of two four-dimensional branes in the five-dimensional space-time, one for the ordinary particles and the other one for mirror particles, and we investigate neutrino masses and mixings in this scheme. Comparison of experimental neutrino data with the predictions of the model leads to various restrictions on the parameters of the model. For instance, the size of the extra dimension, R, turns out to be bounded from below. Cosmological considerations seem to favor a large R. The usual mixing schemes proposed as solutions to the solar and atmospheric neutrino anomalies are compatible with our model.

  12. Constraints on singlet right-handed neutrinos coming from the Z0-width

    We study the constraints on masses and mixing angles imposed by the measured Z deg invisible width, in a model in which a singlet right-handed neutrino mixes with all the Standard Model neutrinos. (author)

  13. Light sterile neutrinos, lepton number violating interactions and short baseline neutrino experiments

    Babu, K. S.; McKay, D. W.; Mocioiu, Irina; Pakvasa, Sandip

    2016-06-01

    We develop the consequences of introducing a purely leptonic, non-standard interaction (NSI) ΔL = 2, four-fermion effective Lagrangian and standard model neutrino mixing with a fourth, sterile neutrino in the analysis of short-baseline, neutrino experiments. We focus on the muon decay at rest (DAR) results from the Liquid Scintillation Neutrino Experiment (LSND) and the Karlsruhe and Rutherford medium Energy Neutrino Experiment (KARMEN), seeking a reconciliation between the two. Both v¯e appearance from v¯μ oscillation and v¯e survival after production from NSI decay of the µ+ contribute to the expected signal. This is a unique feature of our scheme. We comment on further implications of the lepton number violating interaction and sterile neutrino-standard neutrino mixing.

  14. Neutrino Mass Hierarchy and Stepwise Spectral Swapping of Supernova Neutrino Flavors

    We examine a phenomenon recently predicted by numerical simulations of supernova neutrino flavor evolution: the swapping of supernova νe and νμ,τ energy spectra below (above) energy EC for the normal (inverted) neutrino mass hierarchy. We present the results of large-scale numerical calculations which show that in the normal neutrino mass hierarchy case, EC decreases as the assumed effective 2x2 vacuum νeνμ,τ mixing angle (≅θ13) is decreased. In contrast, these calculations indicate that EC is essentially independent of the vacuum mixing angle in the inverted neutrino mass hierarchy case. With a good neutrino signal from a future galactic supernova, the above results could be used to determine the neutrino mass hierarchy even if θ13 is too small to be measured by terrestrial neutrino oscillation experiments

  15. Atmospheric neutrinos, nu_e-nu_s oscillations, and a novel neutrino evolution equation

    Akhmedov, Evgeny

    2016-01-01

    If a sterile neutrino nu_s with an eV-scale mass and a sizeable mixing to the electron neutrino exists, as indicated by the reactor and gallium neutrino anomalies, a strong resonance enhancement of nu_e-nu_s oscillations of atmospheric neutrinos should occur in the TeV energy range. At these energies neutrino flavour transitions in the 3+1 scheme depend on just one neutrino mass squared difference and are fully described within a 3-flavour oscillation framework. We demonstrate that the flavour transitions of atmospheric nu_e can actually be very accurately described in a 2-flavour framework, with neutrino flavour evolution governed by an inhomogeneous Schroedinger-like equation. Evolution equations of this type have not been previously considered in the theory of neutrino oscillations.

  16. Axions, majorons and neutrino masses

    We point out that there is an intimate connection between the seesaw scale for the light neutrinos and the invisible axion scale based on a series of recent investigations on the neutrino masses and mixings within a class of realistic SO(10) models. We can then extend the standard model accordingly so that both the standard invisible axion and majoron can be treated in a naturally unified manner. 7 refs

  17. Multipartite entanglement in neutrino oscillations

    Particle mixing is related to multi-mode entanglement of single-particle states The occupation number of both flavor eigenstates and mass eigenstates can be used to define a multiqubit space. In such a framework, flavor neutrino states can be interpreted as multipartite mode-entangled states. By using two different entanglement measures, we analyze the behavior of multipartite entanglement in the phenomenon of neutrino oscillations.

  18. Multipartite entanglement in neutrino oscillations

    Blasone, Massimo; Dell' Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio, E-mail: blasone@sa.infn.i [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)

    2009-06-01

    Particle mixing is related to multi-mode entanglement of single-particle states The occupation number of both flavor eigenstates and mass eigenstates can be used to define a multiqubit space. In such a framework, flavor neutrino states can be interpreted as multipartite mode-entangled states. By using two different entanglement measures, we analyze the behavior of multipartite entanglement in the phenomenon of neutrino oscillations.

  19. Solar Neutrinos

    Bellini, G.; Ranucci, G.

    2010-01-01

    Solar neutrino investigation has represented one of the most active field of particle physics over the past decade, accumulating important and sometimes unexpected achievements. After reviewing some of the most recent impressive successes, the future perspectives of this exciting area of neutrino research will be discussed.

  20. Quantum decoherence effect and neutrino oscillation

    Sun, C P

    1998-01-01

    In the view of the quantum dynamic theory of measurement developed from the Hepp-Colemen (HC) model (K. Hepp, Hev.Phys.Acta, {\\bf 45}, 237 (1972)), the quantum decoherence in neutrino flavor oscillation caused by an environment surrounding neutrinos is generally considered in this paper. The Ellis, Hagelin, Nanopoulos and Srednicki (EHNS) mechanism for solving the solar neutrino problem can be comprehended in a framework of the ordinary quantum mechanics. In the weak- coupling limit, a microscopic model is proposed to describe the transition of two neutrino system from a pure state to a mixed state. It gives the modified formula of survival probability of neutrino oscillation with two additional time-dependent parameters. For specified environments, this result shows that the oscillating phenomena of neutrino still exist even without a mass difference in free neutrino.

  1. Neutrino oscillations in strong magnetic fields

    Neutrino conversion processes between two neutrino species and the corresponding oscillations induced by strong magnetic fields are considered. The value of the critical strength of magnetic field Bcr as a function of characteristics of neutrinos in vacuum (Δm2ν, mixing angle θ), effective particle density of matter neff, neutrino (transition) magnetic moment μ-tilde and energy E is introduced. It is shown that the neutrino conversion and oscillations effects induced by magnetic fields B ≥ Bcr are important and may result in the depletion of the initial type of ν's in the bunch. A possible increase of these effects in the case when neutrinos pass through a sudden decrease of density of matter (''cross-boundary effect'') and applications to neutrinos from neutron stars and supernova are discussed. (author). 25 refs

  2. Reactor Neutrino Experiments: $\\theta_{13}$ and Beyond

    Qian, X

    2014-01-01

    We review the current-generation short-baseline reactor neutrino experiments that have firmly established the third neutrino mixing angle $\\theta_{13}$ to be non-zero. The relative large value of $\\theta_{13}$ (around 9$^\\circ$) has opened many new and exciting opportunities for future neutrino experiments. Daya Bay experiment with the first measurement of $\\Delta m^2_{ee}$ is aiming for a precision measurement of this atmospheric mass-squared splitting with a comparable precision as $\\Delta m^2_{\\mu\\mu}$ from accelerator muon neutrino experiments. JUNO, a next-generation reactor neutrino experiment, is targeting to determine the neutrino mass hierarchy with medium baselines ($\\sim$50 km). Beside these {\\color{black} opportunities enabled by the large $\\theta_{13}$}, the current-generation (Daya Bay, Double Chooz, and RENO) and the next-generation (JUNO, RENO-50, and PROSPECT) reactor experiments, with their unprecedented statistics, are also leading the precision era of the 3-flavor neutrino oscillation phys...

  3. Neutrino magnetohydrodynamics

    A new neutrino magnetohydrodynamics (NMHD) model is formulated, where the effects of the charged weak current on the electron-ion magnetohydrodynamic fluid are taken into account. The model incorporates in a systematic way the role of the Fermi neutrino weak force in magnetized plasmas. A fast neutrino-driven short wavelengths instability associated with the magnetosonic wave is derived. Such an instability should play a central role in strongly magnetized plasma as occurs in supernovae, where dense neutrino beams also exist. In addition, in the case of nonlinear or high frequency waves, the neutrino coupling is shown to be responsible for breaking the frozen-in magnetic field lines condition even in infinite conductivity plasmas. Simplified and ideal NMHD assumptions were adopted and analyzed in detail

  4. Neutrino magnetohydrodynamics

    Haas, Fernando; Pascoal, Kellen Alves [Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Mendonça, José Tito [IPFN, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal and Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo, SP (Brazil)

    2016-01-15

    A new neutrino magnetohydrodynamics (NMHD) model is formulated, where the effects of the charged weak current on the electron-ion magnetohydrodynamic fluid are taken into account. The model incorporates in a systematic way the role of the Fermi neutrino weak force in magnetized plasmas. A fast neutrino-driven short wavelengths instability associated with the magnetosonic wave is derived. Such an instability should play a central role in strongly magnetized plasma as occurs in supernovae, where dense neutrino beams also exist. In addition, in the case of nonlinear or high frequency waves, the neutrino coupling is shown to be responsible for breaking the frozen-in magnetic field lines condition even in infinite conductivity plasmas. Simplified and ideal NMHD assumptions were adopted and analyzed in detail.

  5. Highlights on experimental neutrino physics

    Full text: In the last years a remarkable progress was achieved in a deeper understanding of neutrino sector. Nowadays we know all mixing angles and mass splits which govern the neutrino oscillation phenomena. The parameters of neutrino mixing were measured by combining results of different experimental approaches including accelerator beams, nuclear reactors, radiative decays and astrophysical neutrinos. Nevertheless, there are open questions which can be viewed as key points to consolidate our knowledge on the intrinsic properties of neutrinos such as mass hierarchy and the existence of a CP violation in leptonic sector. To answer these questions and also to improve the precision of the already known mixing parameters, a series of huge experimental efforts are being set up, even in a world-wide scale in some cases. In this presentation I will review the current knowledge of the fundamental properties of neutrinos and the experimental scenario in which we expect, in a time frame of a decade, to find missing pieces in the leptonic sector. The findings can strengthen the foundations of the Standard Model as well as open very interesting paths for new physics. (author)

  6. Method of Fission Product Beta Spectra Measurements for Predicting Reactor Anti-neutrino Emission

    Asner, D. M.; Burns, K; Campbell, L. W.; Greenfield, B.; Kos, M. S.; Orrell, J. L.; Schram, M.; VanDevender, B.; Wood, L. S.; Wootan, D. W.

    2014-01-01

    The nuclear fission process that occurs in the core of nuclear reactors results in unstable, neutron rich fission products that subsequently beta decay and emit electron anti-neutrinos. These reactor neutrinos have served neutrino physics research from the initial discovery of the neutrino to current precision measurements of neutrino mixing angles. The prediction of the absolute flux and energy spectrum of the emitted reactor neutrinos hinges upon a series of seminal papers based on measurem...

  7. Split neutrinos - leptogenesis, dark matter and inflation

    Mazumdar, Anupam; Morisi, Stefano

    2012-01-01

    We propose a simple framework to split neutrinos with a slight departure from tribimaximal mixing - where two of the neutrinos are Majorana type which provide thermal leptogenesis. The Dirac neutrino with a tiny Yukawa coupling explains primordial inflation and the cosmic microwave background radiation, where the inflaton is the gauge invariant flat direction. The observed baryon asymmetry, and the scale of inflation are intimately tied to the observed reactor angle, which can be further cons...

  8. Revisiting the texture zero neutrino mass matrices

    Singh, Madan; Gupta, Manmohan

    2016-01-01

    In the light of refined and large reactor mixing angle $\\theta_{13}$, we have revisited the texture three and two zero neutrino mass matrices in the flavor basis. For Majorana neutrinos, it has been explicitly shown that all the texture three zero mass matrices remain ruled out. Further, for both normal and inverted mass ordering, for the texture two zero neutrino mass matrices one finds interesting constraints on the Dirac-like CP violating phase $\\delta$ and Majorana phases $\\rho$ and $\\sigma$.

  9. The Daya Bay Reactor Neutrino Experiment

    2012-01-01

    On Aug.15, 201l, a new large-scale scientific facility in China, Daya Bay Reactor Neutrino Experiment, started to operate. It is located in Daya Bay Nuclear Power Plant in Guangdong Province, around 50kin to both Hong Kong and Shenzhen City. The main scientific goal is to precisely determine the neutrino mixing angle 013 by detecting neutrinos from the reactors at different distances.

  10. Neutrino mass and oscillation: An introductory review

    D P Roy

    2000-01-01

    After a brief introduction to neutrino mass via the see-saw model I discuss neutrinomixing and oscillation, first in vacuum and then its matter enhancement. Then the solar and atmospheric neutrino oscillation data are briefly reviewed. Finally I discuss the problem of reconciling hierarchical neutrino masses with at least one large mixing, as implied by these data. A minimal see-saw model for reconciling the two is discussed.

  11. Constraints on the Neutrino Mass from Cosmology and their impact on world neutrino data

    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

  12. Neutrino Mass Matrix from Seesaw Mechanism Subjected to Texture Zero and Invariant Under a Cyclic Permutation

    Damanik, Asan; Muslim,; Anggraita, Pramudita

    2007-01-01

    We evaluate the predictive power of the neutrino mass matrices arising from seesaw mechanism subjected to texture zero and satisfying a cyclic permutation invariant. We found that only two from eight possible patterns of the neutrino mass matrices are invariant under a cyclic permutation. The two resulted neutrino mass matrices which are invariant under a cyclic permutation can be used qualitatively to explain the neutrino mixing phenomena for solar neutrino and to derive the mixing angle that agress with the experimental data.

  13. Academic Training: Neutrino Physics, Present and Future

    2006-01-01

    2006-2007 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 27, 28, 29, 30 November, 1st December, from 11:00 to 12:00 - TH Auditorium, bldg 4 - 3 - 006 Neutrino Physics, Present and Future B. KAYSER / Fermilab, USA Our understanding of neutrinos has been revolutionized by the discovery that they have nonzero masses and very large mixing. We will explain the phenomenology of massive neutrinos, including neutrino oscillation in vacuum and in matter, and the physics of neutrinos that are their own antiparticles. We will review the evidence for neutrino masses and mixing, and summarize what has been learned about the neutrinos so far. Identifying the very interesting open questions raised by the discovery of neutrino mass, we will discuss how these questions may be answered through future experiments. Finally, we will consider the possibility that CP violation by neutrinos is the key to understanding the matter-antimatter asymmetry of the universe, and discuss the see-saw theory of why neutrino masses are so tiny....

  14. Academic Training: Neutrino Physics, Present and Future

    2006-01-01

    2006-2007 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 27, 28, 29, 30 November, 1st December, from 11:00 to 12:00 - TH Auditorium, bldg 4 - 3 - 006 Neutrino Physics, Present and Future B. KAYSER, Fermilab, USA Our understanding of neutrinos has been revolutionized by the discovery that they have nonzero masses and very large mixing. We will explain the phenomenology of massive neutrinos, including neutrino oscillation in vacuum and in matter, and the physics of neutrinos that are their own antiparticles. We will review the evidence for neutrino masses and mixing, and summarize what has been learned about the neutrinos so far. Identifying the very interesting open questions raised by the discovery of neutrino mass, we will discuss how these questions may be answered through future experiments. Finally, we will consider the possibility that CP violation by neutrinos is the key to understanding the matter-antimatter asymmetry of the universe, and discuss the see-saw theory of why neutrino masses are so tiny....

  15. LOS ALAMOS: New neutrino experiment

    Full text: The Liquid Scintillator Neutrino Detector (LSND) experiment at Los Alamos' Meson Physics Facility (LAMPF) has been designed for a high sensitivity search for oscillations between muon- and electron-type neutrinos and, concurrently, between the corresponding antineutrinos. In addition, the experiment will measure neutrino-proton elastic scattering, thereby determining the strange quark contribution to the proton spin. At low momentum transfer, neutrino-proton elastic scattering is a direct probe of this contribution. The detector tank, filled with 200 tons of dilute liquid scintillator, has 1220 8'' Hamamatsu photomultiplier tubes mounted on the inside, covering 25% of the surface area. The dilute liquid scintillator is a mixture of mineral oil and 0.03 g/l of b-PBD, so that Cherenkov and scintillation light will be detected in an approximate ratio of 1 to 4. The attenuation length of the scintillator is greater than 30 m for wavelengths above 425 nm. After two years of data collection for (anti)neutrino mixing, the upper limits on the square of the mass difference will be 1.7 x 10-2 ev2 for maximal mixing for antineutrinos and 4.0 x 10-2 for neutrinos. Similarly, mixing strengths of 2.7 x 10-4 can be probed for each channel for all squared mass differences above 1eV2. This will provide the best terrestrial limits on oscillations between muon- and electron-type neutrinos. In addition, the neutrino-proton elastic scattering reaction rate will be measured to an accuracy of 10, determining the strange quark contribution to the proton spin to within ±0.05. Other physics goals include measurements of the charged current reactions where the neutrinos produce electrons or muons, the inelastic neutral current reaction where the neutrino stays a neutrino but excites the target, and a search for the 'rare' decays of a neutral pion and an eta into a neutrino-antineutrino pair. The LSND collaboration includes groups from California at

  16. Mixed

    Pau Baya

    2011-05-01

    Full Text Available Remenat (Catalan (Mixed, "revoltillo" (Scrambled in Spanish, is a dish which, in Catalunya, consists of a beaten egg cooked with vegetables or other ingredients, normally prawns or asparagus. It is delicious. Scrambled refers to the action of mixing the beaten egg with other ingredients in a pan, normally using a wooden spoon Thought is frequently an amalgam of past ideas put through a spinner and rhythmically shaken around like a cocktail until a uniform and dense paste is made. This malleable product, rather like a cake mixture can be deformed pulling it out, rolling it around, adapting its shape to the commands of one’s hands or the tool which is being used on it. In the piece Mixed, the contortion of the wood seeks to reproduce the plasticity of this slow heavy movement. Each piece lays itself on the next piece consecutively like a tongue of incandescent lava slowly advancing but with unstoppable inertia.

  17. Entanglement in neutrino oscillations

    Blasone, Massimo; Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio

    2007-01-01

    Flavor oscillations in elementary particle physics are related to multi-mode entanglement of single-particle states. We show that mode entanglement can be expressed in terms of flavor transition probabilities, and therefore that single-particle entangled states acquire a precise operational characterization in the context of particle mixing. We treat in detail the physically relevant cases of two- and three-flavor neutrino oscillations, including the effective measure of CP violation. We disc...

  18. Search for Massive Neutrinos in the Decay pi --> e nu

    Aoki, M; Bryman, D A; Chen, S; Ding, M; Doria, L; Gumplinger, P; Hurst, C; Hussein, A; Igarashi, Y; Ito, N; Kettell, S H; Kurchaninov, L; Littenberg, L; Malbrunot, C; Numao, T; Poutissou, R; Sher, A; Sullivan, T; Yamada, K; Yoshida, M; Vavilov, D

    2011-01-01

    Evidence of massive neutrinos in the pi --> e nu decay spectrum was sought with the background pi --> mu --> e decay chain highly suppressed. Upper limits (90% C.L.) on the neutrino mixing matrix element |U_ei|^2 in the neutrino mass region 60--129 MeV/c^2 were set at the level of 10^-8.

  19. An overview of the Daya Bay Reactor Neutrino Experiment

    Cao, Jun

    2016-01-01

    The Daya Bay Reactor Neutrino Experiment discovered an unexpectedly large neutrino oscillation related to the mixing angle $\\theta_{13}$ in 2012. This finding paved the way to the next generation of neutrino oscillation experiments. In this article, we review the history, featured design, and scientific results of Daya Bay. Prospects of the experiment are also described.

  20. Neutrino properties from observations of SN 1987A

    Observations of the neutrino burst from SN 1987A by KAMIOKANDE II and IMB water Cherenkov detectors are discussed. They yield strong constraints on the lifetime, mass, mixings, electric charge and magnetic moment of the electron neutrino and on the number of flavors of light neutrinos

  1. Light sterile neutrino production in the early universe with dynamical neutrino asymmetries

    Mirizzi, Alessandro; Miele, Gennaro; Serpico, Pasquale Dario

    2012-01-01

    Light sterile neutrinos mixing with the active ones have been recently proposed to solve different anomalies observed in short-baseline oscillation experiments. These neutrinos can also be produced by oscillations of the active neutrinos in the early universe, leaving possible traces on different cosmological observables. Here we perform an updated study of the neutrino kinetic equations in (3+1) and (2+1) oscillation schemes, dynamically evolving primordial asymmetries of active neutrinos and taking into account for the first time CP-violation effects. In the absence of neutrino asymmetries, eV-mass scale sterile neutrinos would be completely thermalized creating a tension with respect to the CMB, LSS and BBN data. In the past literature, active neutrino asymmetries have been invoked as a way to inhibit the sterile neutrino production via the in-medium suppression of the sterile-active mixing angle. However, neutrino asymmetries also permit a resonant sterile neutrino production. We find that if the active s...

  2. Generalized mass ordering degeneracy in neutrino oscillation experiments

    Coloma, Pilar

    2016-01-01

    We consider the impact of neutral-current (NC) non-standard neutrino interactions (NSI) on the determination of the neutrino mass ordering. We show that in presence of NSI there is an exact degeneracy which makes it impossible to determine the neutrino mass ordering and the octant of the solar mixing angle $\\theta_{12}$ at oscillation experiments. The degeneracy holds at the probability level and for arbitrary matter density profiles, and hence, solar, atmospheric, reactor, and accelerator neutrino experiments are affected simultaneously. The degeneracy requires order-one corrections from NSI to the NC electron neutrino--quark interaction and can be tested in electron neutrino NC scattering experiments.

  3. A theoretical perspective on neutrino physics

    A survey of sin2 θW, ρ, CKM matrix, and axial-isoscalar neutral current measurements via neutrino scattering is presented. Loop effects due to heavy top or a fourth generation are described. Neutrino oscillations are discussed in a three generation mixing framework and some motivation for νμ → ντ oscillation searches is given. 15 refs., 1 tab

  4. Updating neutrino magnetic moment constraints

    B.C. Cañas

    2016-02-01

    Full Text Available In this paper we provide an updated analysis of the neutrino magnetic moments (NMMs, discussing both the constraints on the magnitudes of the three transition moments Λi and the role of the CP violating phases present both in the mixing matrix and in the NMM matrix. The scattering of solar neutrinos off electrons in Borexino provides the most stringent restrictions, due to its robust statistics and the low energies observed, below 1 MeV. Our new limit on the effective neutrino magnetic moment which follows from the most recent Borexino data is 3.1×10−11μB at 90% C.L. This corresponds to the individual transition magnetic moment constraints: |Λ1|≤5.6×10−11μB, |Λ2|≤4.0×10−11μB, and |Λ3|≤3.1×10−11μB (90% C.L., irrespective of any complex phase. Indeed, the incoherent admixture of neutrino mass eigenstates present in the solar flux makes Borexino insensitive to the Majorana phases present in the NMM matrix. For this reason we also provide a global analysis including the case of reactor and accelerator neutrino sources, presenting the resulting constraints for different values of the relevant CP phases. Improved reactor and accelerator neutrino experiments will be needed in order to underpin the full profile of the neutrino electromagnetic properties.

  5. Determinations of flavor ratios and flavor transitions of astrophysical neutrinos

    Lin, Guey-Lin; Liu, Tsung-Che; Lai, Kwang-Chang [Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan (China); Huang, Minghuey [National United University, Lianda, Miaoli City, Miaoli County 360, Taiwan (China)

    2010-07-01

    We argue that effective flavor discrimination in neutrino telescopes is the key to probe the flavor ratios of astrophysical neutrinos at the source [1,3] and flavor transition mechanisms [2] of these neutrinos during their propagations from the source to the Earth. We first discuss how well one can reconstruct the flavor ratios of astrophysical neutrinos at the source, given achievable efficiencies of neutrino telescopes in flavor discriminations and expected understandings of neutrino mixing parameters in the future. It will be shown that the signatures for tau neutrinos are energy dependent, hence the methods for flavor reconstruction depend on neutrino energies as well. We then discuss how to probe flavor transition mechanisms of propagating astrophysical neutrinos. In this regard, we propose a model independent parametrization for neutrino flavor transitions, with the neutrino oscillation as a special case. We illustrate how one can determine parameters of this parameterization by neutrino telescope measurements. The situation with non-conservation of neutrino flux during neutrino propagations (such as that caused by neutrino decays) is also discussed. Refs.: [1] T. C. Liu, M. A. Huang and G. L. Lin, arXiv: 1004.5154. [2] K. C. Lai, G. L. Lin and T. C. Liu, arXiv: 1004.1583. [3] K. C. Lai, G. L. Lin and T. C. Liu, Phys. Rev. D80, 103005 (2009). (authors)

  6. Neutrino physics

    The basic concepts of neutrino physics are presented at a level appropriate for integration into elementary courses on quantum mechanics and/or modern physics. (c) 2000 American Association of Physics Teachers

  7. Neutrino cosmology

    Lesgourgues, Julien; Miele, Gennaro; Pastor, Sergio

    2013-01-01

    The role that neutrinos have played in the evolution of the Universe is the focus of one of the most fascinating research areas that has stemmed from the interplay between cosmology, astrophysics and particle physics. In this self-contained book, the authors bring together all aspects of the role of neutrinos in cosmology, spanning from leptogenesis to primordial nucleosynthesis, their role in CMB and structure formation, to the problem of their direct detection. The book starts by guiding the reader through aspects of fundamental neutrino physics, such as the standard cosmological model and the statistical mechanics in the expanding Universe, before discussing the history of neutrinos in chronological order from the very early stages until today. This timely book will interest graduate students and researchers in astrophysics, cosmology and particle physics, who work with either a theoretical or experimental focus.

  8. Sterile neutrino production in models with low reheating temperatures

    Yaguna, Carlos E

    2007-01-01

    By numerically solving the appropriate Boltzmann equations, we study the production of sterile neutrinos in models with low reheating temperatures. We take into account the production in oscillations as well as in direct decays and compute the sterile neutrino primordial spectrum, the effective number of neutrino species, and the sterile neutrino contribution to the mass density of the Universe as a function of the mixing and the reheating parameters. It is shown that sterile neutrinos with non-negligible mixing angles do not necessarily lead to $N_\

  9. Possible explanation of the solar-neutrino puzzle

    Bethe, H. A.

    1986-01-01

    A new derivation of the Mikheyev and Smirnov (1985) mechanism for the conversion of electron neutrinos into mu neutrinos when traversing the sun is presented, and various hypotheses set forth. It is assumed that this process is responsible for the detection of fewer solar neutrinos than expected, with neutrinos below a minimum energy, E(m), being undetectable. E(m) is found to be about 6 MeV, and the difference of the squares of the respective neutrino masses is calculated to be 6 X 10 to the - 5th sq eV. A restriction on the neutrino mixing angle is assumed such that the change of density near the crossing point is adiabatic. It is predicted that no resonance conversion of neutrinos will occur in the dense core of supernovae, but conversion of electron neutrinos to mu neutrinos will occur as they escape outward through a density region around 100.

  10. Sterile neutrinos

    Kopp, J.; Machado, P. A. N.; Maltoni, M.; Schwetz, T.

    2016-06-01

    We characterize statistically the indications of a presence of one or more light sterile neutrinos from MiniBooNE and LSND data, together with the reactor and gallium anomalies, in the global context. The compatibility of the aforementioned signals with null results from solar, atmospheric, reactor, and accelerator experiments is evaluated. We conclude that a severe tension is present in the global fit, and therefore the addition of eV-scale sterile neutrinos does not satisfactorily explain the anomalies.

  11. Precision measurement of neutrino oscillation parameters at INO-ICAL detector

    Daljeet Kaur; Md Naimuddin; Sanjeev Kumar Verma

    2016-02-01

    A magnetized Iron CALorimeter (ICAL) detector at the India-based neutrino observatory (INO) is used to study neutrino oscillation sensitivity using atmospheric muon neutrino source. The ICAL detector will be able to detect muon tracks and hadron showers produced by neutrino interactions with the iron target. We have performed precision measurement analysis for the atmospheric neutrino oscillation parameters with the muon neutrino events, generated by Monte Carlo NUANCE event generator. A marginalized 2 analysis based on reconstructed neutrino energy and muon zenith angle binning scheme has been performed to determine the sensitivity for the atmospheric neutrino mixing parameters, ${\\rm sin}^{2} \\theta_{23}$ and $|\\Delta m^{2}_{23}|$.

  12. Neutrino oscillations: Present status and outlook

    Thomas Schwetz

    2009-01-01

    The status of neutrino oscillations from global data is summarized, with the focus on the three-flavour picture. The status of sterile neutrino oscillation interpretations of the LSND anomaly in the light of recent MiniBooNE results is also discussed. Further-more, an outlook on the measurement of the mixing angle 13 in the near term future, as well as prospects to discover CP violation in neutrino oscillations and to determine the type of the neutrino mass ordering by long-baseline experiments in the long term future are given.

  13. A dynamical collective calculation of supernova neutrino signals

    Gava, J.; Kneller, J.; Volpe, C.; McLaughlin, G.C.

    2009-01-01

    We present the first calculations with three flavors of collective and shock wave effects for neutrino propagation in core-collapse supernovae using hydroynamical density profiles and the S matrix formalism. We explore the interplay between the neutrino-neutrino interaction and the effects of multiple resonances upon the time signal of positrons in supernova observatories. A specific signature is found for the inverted hierarchy and a large third neutrino mixing angle and we predict, in this ...

  14. Neutrino Oscillations as a Probe of Light Scalar Dark Matter

    Berlin, Asher

    2016-01-01

    We consider a class of models involving interactions between ultra-light scalar dark matter and Standard Model neutrinos. Such couplings modify the neutrino mass splittings and mixing angles to include additional components that vary in time periodically with a frequency and amplitude set by the mass and energy density of the dark matter. Null results from recent searches for anomalous periodicities in the solar neutrino flux strongly constrain the dark matter-neutrino coupling to be orders o...

  15. Search for Sterile Neutrinos at OPERA and other Long--Baseline Experiments

    Stanco, Luca

    2015-01-01

    The OPERA experiment at the CNGS beam has observed muon to tau neutrino oscillations in the atmospheric sector. Based on this result new limits on the mixing parameters of a massive sterile neutrino may be set. Preliminary results of the analysis done in the 3+1 neutrino framework are here presented. An update of the search for sterile neutrinos in the $\

  16. Sterile Neutrinos in Cold Climates

    Jones, Benjamin J.P. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-09-01

    Measurements of neutrino oscillations at short baselines contain an intriguing set of experimental anomalies that may be suggestive of new physics such as the existence of sterile neutrinos. This three-part thesis presents research directed towards understanding these anomalies and searching for sterile neutrino oscillations. Part I contains a theoretical discussion of neutrino coherence properties. The open-quantum-system picture of neutrino beams, which allows a rigorous prediction of coherence distances for accelerator neutrinos, is presented. Validity of the standard treatment of active and sterile neutrino oscillations at short baselines is verified, and non-standard coherence loss effects at longer baselines are predicted. Part II concerns liquid argon detector development for the MicroBooNE experiment, which will search for short-baseline oscillations in the Booster Neutrino Beam at Fermilab. Topics include characterization and installation of the MicroBooNE optical system; test-stand measurements of liquid argon optical properties with dissolved impurities; optimization of wavelength-shifting coatings for liquid argon scintillation light detection; testing and deployment of high-voltage surge arrestors to protect TPC field cages; and software development for optical and TPC simulation and reconstruction. Part III presents a search for sterile neutrinos using the IceCube neutrino telescope, which has collected a large sample of atmospheric-neutrino-induced events in the 1-10 TeV energy range. Sterile neutrinos would modify the detected neutrino flux shape via MSW-resonant oscillations. Following a careful treatment of systematic uncertainties in the sample, no evidence for MSW-resonant oscillations is observed, and exclusion limits on 3+1 model parameter space are derived. Under the mixing assumptions made, the 90% confidence level exclusion limit extends to sin224 ≤ 0.02 at m2 ~ 0.3 eV2, and the LSND and Mini

  17. Neutrino observables from predictive flavour patterns

    Cebola, Luis M.; Emmanuel-Costa, David [Universidade de Lisboa, Departamento de Fisica and Centro de Fisica Teorica de Particulas - CFTP, Instituto Superior Tecnico, Lisboa (Portugal); Felipe, Ricardo Gonzalez [Universidade de Lisboa, Departamento de Fisica and Centro de Fisica Teorica de Particulas - CFTP, Instituto Superior Tecnico, Lisboa (Portugal); ISEL - Instituto Superior de Engenharia de Lisboa, Instituto Politecnico de Lisboa, Lisboa (Portugal)

    2016-03-15

    We look for predictive flavour patterns of the effective Majorana neutrino mass matrix that are compatible with current neutrino oscillation data. Our search is based on the assumption that the neutrino mass matrix contains equal elements and a minimal number of parameters, in the flavour basis where the charged lepton mass matrix is diagonal and real. Three unique patterns that can successfully explain neutrino observables at the 3σ confidence level with just three physical parameters are presented. Neutrino textures described by four and five parameters are also studied. The predictions for the lightest neutrino mass, the effective mass parameter in neutrinoless double beta decays and for the CP-violating phases in the leptonic mixing are given. (orig.)

  18. Neutrino observables from predictive flavour patterns

    Cebola, Luis M; Felipe, Ricardo Gonzalez

    2016-01-01

    We look for predictive flavour patterns of the effective Majorana neutrino mass matrix that are compatible with current neutrino oscillation data. Our search is based on the assumption that the neutrino mass matrix contains equal elements and a minimal number of parameters, in the flavour basis where the charged lepton mass matrix is diagonal and real. Three unique patterns that can successfully explain neutrino observables at the $3\\sigma$ confidence level with just three physical parameters are presented. Neutrino textures described by four and five parameters are also studied. The predictions for the lightest neutrino mass, the effective mass parameter in neutrinoless double beta decays and the CP-violating phases in the leptonic mixing are given.

  19. Dynamical collective calculation of supernova neutrino signals.

    Gava, Jérôme; Kneller, James; Volpe, Cristina; McLaughlin, G C

    2009-08-14

    We present the first calculations with three flavors of collective and shock wave effects for neutrino propagation in core-collapse supernovae using hydrodynamical density profiles and the S matrix formalism. We explore the interplay between the neutrino-neutrino interaction and the effects of multiple resonances upon the time signal of positrons in supernova observatories. A specific signature is found for the inverted hierarchy and a large third neutrino mixing angle and we predict, in this case, a dearth of lower energy positrons in Cherenkov detectors midway through the neutrino signal and the simultaneous revelation of valuable information about the original fluxes. We show that this feature is also observable with current generation neutrino detectors at the level of several sigmas. PMID:19792628

  20. Testing constrained sequential dominance models of neutrinos

    Björkeroth, Fredrik; King, Stephen F.

    2015-12-01

    Constrained sequential dominance (CSD) is a natural framework for implementing the see-saw mechanism of neutrino masses which allows the mixing angles and phases to be accurately predicted in terms of relatively few input parameters. We analyze a class of CSD(n) models where, in the flavour basis, two right-handed neutrinos are dominantly responsible for the ‘atmospheric’ and ‘solar’ neutrino masses with Yukawa couplings to ({ν }e,{ν }μ ,{ν }τ ) proportional to (0,1,1) and (1,n,n-2), respectively, where n is a positive integer. These coupling patterns may arise in indirect family symmetry models based on A 4. With two right-handed neutrinos, using a χ 2 test, we find a good agreement with data for CSD(3) and CSD(4) where the entire Pontecorvo-Maki-Nakagawa-Sakata mixing matrix is controlled by a single phase η, which takes simple values, leading to accurate predictions for mixing angles and the magnitude of the oscillation phase | {δ }{CP}| . We carefully study the perturbing effect of a third ‘decoupled’ right-handed neutrino, leading to a bound on the lightest physical neutrino mass {m}1{{≲ }}1 meV for the viable cases, corresponding to a normal neutrino mass hierarchy. We also discuss a direct link between the oscillation phase {δ }{CP} and leptogenesis in CSD(n) due to the same see-saw phase η appearing in both the neutrino mass matrix and leptogenesis.

  1. Lower bound on neutrino mass and possible CP violation in neutrino oscillations

    Verma, Rohit

    2013-01-01

    The phenomenology of the most general lepton mass matrices obtained through weak basis transformations has been discussed. Using a hierarchical parametrization of these mass matrices, the exact relations for lepton mixing angles have been obtained assuming normal neutrino mass hierarchy and natural structures of lepton mass matrices. The recent three neutrino oscillation data together with the condition of naturalness on Dirac lepton mass matrices provide a lower bound on the lightest neutrino mass of m{\

  2. Future Neutrino Long Baseline Experiments

    A new generation of reactor and accelerator neutrino oscillation experiments - Double Chooz, Daya Bay, Reno, T2K and NOA - is ready to start a sensitive search for oscillation signals generated by the mixing parameter θ13. Their output will be a fundamental milestone to optimize further experiments aimed at detecting CP violation in the neutrino sector, a key phenomenon with profound implications in particle physics and cosmology. Since late 90s, a world-wide activity is in progress to design facilities that can access CP violation in neutrino oscillation and perform high precision measurements of the lepton mixing matrix. In this paper the status of these studies will be summarized, focusing on the options that are best suited to exploit existing European facilities. (author)

  3. Boron neutrino flux and resonant conversion of solar neutrinos

    In view of large uncertainties in the prediction of the boron neutrino flux from the Sun we consider the magnitude of this flux, ΦB, as a parameter to be found from experiment. A consistent description of the data in terms of neutrino resonance conversion admits ΦB/Φ0B=0.4 - 2.5 in small mixing domain and ΦB/Φ0B=1 - 3 in large mixing domain, (here φ0B ≡ 5.7 · 106 cm-2s-1 is the flux in the reference SSM). Variations of the flux within these intervals enlarge the allowed region of mixing angles to sin22θ=(0.06 -2) · 10-2 and sin22θ=0.2 - 0.9 correspondingly. If the value of ΦB is about that measured by Kamiokande, the data fix the region Δm2 ∼ (4-9) · 10-6 eV2 and sin2 2θ ∼ (0.6 - 2) · 10-3 (''very small mixing solution''). We comment on the possibility to measure the neutrino parameters and the original boron neutrino flux in future experiments. (author). 31 refs, 3 figs, 2 tabs

  4. Effect of tau neutrino contribution to muon signals at neutrino factories

    Indumathi, D

    2009-01-01

    We discuss precision measurements of the leading atmospheric parameters at a standard neutrino factory with a detector that is sensitive to muons alone. The oscillation of the muon- and electron neutrinos in the neutrino factory beam to tau neutrinos adds to the muon events sample (both right sign and wrong sign) via leptonic decays of the taus produced through charge-current interactions in the detector. In particular, we study how this affects a precision measurement of the atmospheric mixing parameters and the deviation of nu_mu nu_tau mixing from maximality. In spite of the enhancement of the number of events due to the additional tau contribution, the determination of the atmospheric mixing angle and the deviation from maximality will be poorer. We show that it is impossible to devise satisfactory cuts to remove this tau contamination. Neglect of these tau contributions will lead to an incorrect conclusion about the precision obtainable at such a neutrino factory.

  5. Solar neutrino oscillation phenomenology

    Srubabati Goswami

    2004-02-01

    This article summarises the status of the solar neutrino oscillation phenomenology at the end of 2002 in the light of the SNO and KamLAND results. We first present the allowed areas obtained from global solar analysis and demonstrate the preference of the solar data towards the large-mixing-angle (LMA) MSW solution. A clear confirmation in favour of the LMA solution comes from the KamLAND reactor neutrino data. the KamLAND spectral data in conjunction with the global solar data further narrows down the allowed LMA region and splits it into two allowed zones - a low $ m^{2}$ region (low-LMA) and high $ m^{2}$ region (high-LMA). We demonstrate through a projected analysis that with an exposure of 3 kton-year (kTy) KamLAND can remove this ambiguity.

  6. Neutrino Catalyzed Diphoton Excess

    Chao, Wei

    2015-01-01

    In this paper we explain the 750 GeV diphoton resonance observed at the run-2 LHC as a scalar singlet $S$, that plays a key rule in generating tiny but nonzero Majorana neutrino masses. The model contains four electroweak singlets: two leptoquarks, a singly charged scalar and a neutral scalar $S$. Majorana neutrino masses might be generated at the two-loop level as $S$ get nonzero vacuum expectation value. $S$ can be produced at the LHC through the gluon fusion and decays into diphoton at the one-loop level with charged scalars running in the loop. The model fits perfectly with a wide width of the resonance. Constraints on the model are investigated, which shows a negligible mixing between the resonance and the standard model Higgs boson.

  7. The three neutrino scenario

    I have discussed in my talk several remaining issues in the standard three-flavor mixing scheme of neutrinos, in particular, the sign of Δm213 and the leptonic CP violating phase. In this report I focus on two topics: (1) supernova method for determining the former sign, and (2) illuminating how one can detect the signatures for both of them in long-baseline (> or approx. 10 km) neutrino oscillation experiments. I do this by formulating perturbative frameworks appropriate for the two typical options of such experiments, the high energy and the low energy options with beam energies of ∼ 10 GeV and ∼ 100 MeV, respectively

  8. A Model for Pseudo-Dirac Neutrinos: Leptogenesis and Ultra-High Energy Neutrinos

    Ahn, Y H; Kim, C S

    2016-01-01

    We propose a model where sterile neutrinos are introduced to make light neutrinos to be pseudo-Dirac particles. It is shown how tiny mass splitting necessary for realizing pseudo-Dirac neutrinos can be achieved. Within the model, we show how leptogenesis can be successfully generated. Motivated by the recent observation of very high energy neutrino events at IceCube, we study a possibility to observe the effects of the pseudo-Dirac property of neutrinos by performing astronomical-scale baseline experiments to uncover the oscillation effects of very tiny mass splitting. Using the result of global fit to neutrino data for the input of neutrino mixing angles and CP phase at $1\\sigma$ C.L. and fixing neutrino energy and mass splittings, we study how the oscillation effects induced by pseudo-Dirac neutrinos may affect the track-to-shower ratio obtained from IceCube data. We also discuss future prospect to observe the effects of the pseudo-Dirac property of neutrinos at high energy neutrino experiments.

  9. Neutrino factory near detector

    Bogomilov, M.; Y. Karadzhov; Matev, R.; Tsenov, R.; Laing, A.; F.J.P. Soler

    2013-01-01

    The neutrino factory is a facility for future precision studies of neutrino oscillations. A so-called near detector is essential for reaching the required precision for a neutrino oscillation analysis. The main task of the near detector is to measure the flux of the neutrino beam. Such a high intensity neutrino source like a neutrino factory provides also the opportunity for precision studies of various neutrino interaction processes in the near detector. We discuss the design concepts of suc...

  10. Neutrino Physics with JUNO

    An, Fengpeng; An, Guangpeng; 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

    2015-01-01

    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,...

  11. Neutrino physics and the mirror world: how exact parity symmetry explains the solar neutrino deficit, the atmospheric neutrino anomaly and the LSND experiment

    Evidence for ν-barμ → ν-bare oscillations has been reported at LAMPF using the LSND detector. Further evidence for neutrino mixing comes from the solar neutrino deficit and the atmospheric neutrino anomaly. All of these anomalies require new physics. It is shown that all of these anomalies can be explained if the standard model is enlarged so that an unbroken parity symmetry can be defined. This explanation holds independently of the actual model for neutrino masses. Thus, it is argued that parity symmetry is not only a beautiful candidate for a symmetry beyond the standard model, but it can also explain the known neutrino physics anomalies. 41 refs

  12. Implications of Fermionic Dark Matter on recent neutrino oscillation data

    Singirala, Shivaramakrishna

    2016-01-01

    We investigate flavor phenomenology and dark matter in the context of scotogenic model. In this model, the neutrino masses are generated through radiative corrections at one-loop level. Considering the neutrino mixing matrix to be of tri-bimaximal form with additional perturbations to accommodate the recently observed non-zero value of reactor mixing angle $\\theta_{13}$, we obtain the relation between various neutrino oscillation parameters and the model parameters. Working in degenerate heav...

  13. Democratic Approach To Atmospheric And Solar Neutrino Oscillations

    Shafi, Qaisar; Shafi, Qaisar; Tavartkiladze, Zurab

    2002-01-01

    Working with a U(1) flavor symmetry, we show how the hierarchical structure in the charged fermion sector and a democratic approach for neutrinos that yields large solar and atmospheric neutrino mixings can be simultaneously realized in the MSSM framework. However, in SU(5) due to the unified multiplets we encounter difficulties. Namely, democracy for the neutrinos leads to a wrong hierarchical pattern for charged fermion masses and mixings. We discuss how this is overcome in flipped SU(5).

  14. Observation of electron neutrino appearance in a muon neutrino beam.

    Abe, K; Adam, J; Aihara, H; Akiri, T; Andreopoulos, C; Aoki, S; Ariga, A; Ariga, T; Assylbekov, S; Autiero, D; Barbi, M; Barker, G J; Barr, G; Bass, M; Batkiewicz, M; Bay, F; Bentham, S W; Berardi, V; Berger, B E; Berkman, S; Bertram, I; 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; Caravaca Rodríguez, J; 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; Di Lodovico, F; Di Luise, S; Drapier, O; Duboyski, T; Duffy, K; Dufour, F; Dumarchez, J; Dytman, S; Dziewiecki, M; Emery, S; Ereditato, A; Escudero, L; Finch, A J; Floetotto, L; Friend, M; Fujii, Y; Fukuda, Y; Furmanski, A P; Galymov, V; Gaudin, A; Giffin, S; Giganti, C; Gilje, K; Goeldi, D; Golan, T; Gomez-Cadenas, J J; 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; Ives, S J; Iyogi, K; Izmaylov, A; Jacob, A; Jamieson, B; Johnson, R A; Jo, J H; Jonsson, P; Jung, C K; Kaboth, A C; Kajita, T; Kakuno, H; Kameda, J; Kanazawa, Y; Karlen, D; Karpikov, I; Kearns, E; Khabibullin, M; Khotjantsev, A; Kielczewska, D; Kikawa, T; Kilinski, A; Kim, J; Kisiel, J; Kitching, P; Kobayashi, T; Koch, L; Kolaceke, A; Konaka, A; Kormos, L L; Korzenev, A; Koseki, K; Koshio, Y; Kreslo, I; Kropp, W; Kubo, H; Kudenko, Y; Kumaratunga, S; Kurjata, R; Kutter, T; Lagoda, J; Laihem, K; Lamont, I; Laveder, M; Lawe, M; Lazos, M; Lee, K P; Licciardi, C; Lindner, T; Lister, C; Litchfield, R P; Longhin, A; Ludovici, L; Macaire, M; Magaletti, L; Mahn, K; Malek, M; Manly, S; Marino, A D; Marteau, J; Martin, J F; Maruyama, T; Marzec, J; Mathie, E L; Matveev, V; Mavrokoridis, K; Mazzucato, E; McCarthy, M; McCauley, N; McFarland, K S; McGrew, C; Metelko, C; Mezzetto, M; Mijakowski, P; Miller, C A; Minamino, A; Mineev, O; Mine, S; Missert, A; Miura, M; Monfregola, L; Moriyama, S; Mueller, Th A; Murakami, A; Murdoch, M; Murphy, S; Myslik, J; Nagasaki, T; Nakadaira, T; Nakahata, M; Nakai, T; Nakamura, K; Nakayama, S; Nakaya, T; Nakayoshi, K; Naples, D; Nielsen, C; Nirkko, M; Nishikawa, K; Nishimura, Y; O'Keeffe, H M; Ohta, R; Okumura, K; Okusawa, T; Oryszczak, W; Oser, S M; Owen, R A; Oyama, Y; Palladino, V; Paolone, V; Payne, D; Pearce, G F; Perevozchikov, O; Perkin, J D; Petrov, Y; Pickard, L J; Pinzon Guerra, E S; Pistillo, C; Plonski, P; Poplawska, E; Popov, B; Posiadala, 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; Retiere, F; Robert, A; Rodrigues, P A; Rojas, P; Rondio, E; Roth, S; Rubbia, A; Ruterbories, D; Sacco, R; Sakashita, K; Sánchez, F; Sato, F; Scantamburlo, E; Scholberg, K; Schwehr, J; Scott, M; Seiya, Y; Sekiguchi, T; Sekiya, H; Sgalaberna, D; Shiozawa, M; Short, S; Shustrov, Y; Sinclair, P; Smith, B; Smith, R J; 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; Szeglowski, T; 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; Ueno, K; 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; Yen, S; Yershov, N; Yokoyama, M; Yuan, T; Zalewska, A; Zalipska, J; Zambelli, L; Zaremba, K; Ziembicki, M; Zimmerman, E D; Zito, M; Zmuda, J

    2014-02-14

    The T2K experiment has observed electron neutrino appearance in a muon neutrino beam produced 295 km from the Super-Kamiokande detector with a peak energy of 0.6 GeV. A total of 28 electron neutrino events were detected with an energy distribution consistent with an appearance signal, corresponding to a significance of 7.3σ when compared to 4.92±0.55 expected background events. In the Pontecorvo-Maki-Nakagawa-Sakata mixing model, the electron neutrino appearance signal depends on several parameters including three mixing angles θ12, θ23, θ13, a mass difference Δm(32)(2) and a CP violating phase δ(CP). In this neutrino oscillation scenario, assuming |Δm(32)(2)|=2.4×10(-3)  eV(2), sin(2)θ(23)=0.5, and Δm322>0 (Δm(32)(2)<0), a best-fit value of sin(2)2θ(13)=0.140(-0.032)(+0.038) (0.170(-0.037)(+0.045)) is obtained at δ(CP)=0. When combining the result with the current best knowledge of oscillation parameters including the world average value of θ(13) from reactor experiments, some values of δ(CP) are disfavored at the 90% C.L. PMID:24580687

  15. Observation of Electron Neutrino Appearance in a Muon Neutrino Beam

    Abe, K; Aihara, H; Akiri, T; Andreopoulos, C; Aoki, S; Ariga, A; Ariga, T; Assylbekov, S; Autiero, D; Barbi, M; Barker, G J; Barr, G; Bass, M; Batkiewicz, M; Bay, F; Bentham, S W; Berardi, V; Berger, B E; Berkman, S; Bertram, I; 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; Rodríguez, 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; Di Lodovico, F; Di Luise, S; Drapier, O; Duboyski, T; Duffy, K; Dufour, F; Dumarchez, J; Dytman, S; Dziewiecki, M; Emery, S; Ereditato, A; Escudero, L; Finch, A J; Floetotto, L; Friend, M; Fujii, Y; Fukuda, Y; Furmanski, A P; Galymov, V; Gaudin, A; Giffin, S; Giganti, C; Gilje, K; Goeldi, D; Golan, T; Gomez-Cadenas, J J; 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; Ives, S J; Iyogi, K; Izmaylov, A; Jacob, A; Jamieson, B; Johnson, R A; Jo, J H; Jonsson, P; Jung, C K; Kaboth, A C; Kajita, T; Kakuno, H; Kameda, J; Kanazawa, Y; Karlen, D; Karpikov, I; Kearns, E; Khabibullin, M; Khotjantsev, A; Kielczewska, D; Kikawa, T; Kilinski, A; Kim, J; Kisiel, J; Kitching, P; Kobayashi, T; Koch, L; Kolaceke, A; Konaka, A; Kormos, L L; Korzenev, A; Koseki, K; Koshio, Y; Kreslo, I; Kropp, W; Kubo, H; Kudenko, Y; Kumaratunga, S; Kurjata, R; Kutter, T; Lagoda, J; Laihem, K; Lamont, I; Laveder, M; Lawe, M; Lazos, M; Lee, K P; Licciardi, C; Lindner, T; Lister, C; Litchfield, R P; Longhin, A; Ludovici, L; Macaire, M; Magaletti, L; Mahn, K; Malek, M; Manly, S; Marino, A D; Marteau, J; Martin, J F; Maruyama, T; Marzec, J; Mathie, E L; Matveev, V; Mavrokoridis, K; Mazzucato, E; McCarthy, M; McCauley, N; McFarland, K S; McGrew, C; Metelko, C; Mijakowski, P; Miller, C A; Minamino, A; Mineev, O; Mine, S; Missert, A; Miura, M; Monfregola, L; Moriyama, S; Mueller, Th A; Murakami, A; Murdoch, M; Murphy, S; Myslik, J; Nagasaki, T; Nakadaira, T; Nakahata, M; Nakai, T; Nakamura, K; Nakayama, S; Nakaya, T; Nakayoshi, K; Naples, D; Nielsen, C; Nirkko, M; Nishikawa, K; Nishimura, Y; O'Keeffe, H M; Ohta, R; Okumura, K; Okusawa, T; Oryszczak, W; Oser, S M; Owen, R A; Oyama, Y; Palladino, V; Paolone, V; Payne, D; Pearce, G F; Perevozchikov, O; Perkin, J D; Petrov, Y; Pickard, L J; Guerra, E S Pinzon; Pistillo, C; Plonski, P; Poplawska, E; Popov, B; Posiadala, 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; Retiere, F; Robert, A; Rodrigues, P A; Rondio, E; Roth, S; Rubbia, A; Ruterbories, D; Sacco, R; Sakashita, K; Sánchez, F; Sato, F; Scantamburlo, E; Scholberg, K; Schwehr, J; Scott, M; Seiya, Y; Sekiguchi, T; Sekiya, H; Sgalaberna, D; Shiozawa, M; Short, S; Shustrov, Y; Sinclair, P; Smith, B; Smith, R J; 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; Szeglowski, T; 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; Ueno, K; 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; Yen, S; Yershov, N; Yokoyama, M; Yuan, T; Zalewska, A; Zalipska, J; Zambelli, L; Zaremba, K; Ziembicki, M; Zimmerman, E D; Zito, M; Żmuda, J

    2013-01-01

    The T2K experiment has observed electron neutrino appearance in a muon neutrino beam produced 295 km from the Super-Kamiokande detector with a peak energy of 0.6 GeV. A total of 28 electron neutrino events were detected with an energy distribution consistent with an appearance signal, corresponding to a significance of 7.3$\\sigma$ when compared to 4.92 $\\pm$ 0.55 expected background events. In the PMNS mixing model, the electron neutrino appearance signal depends on several parameters including three mixing angles $\\theta_{12}$, $\\theta_{23}$, $\\theta_{13}$, a mass difference $\\Delta m^2_{32}$ and a CP violating phase $\\delta_{\\mathrm{CP}}$. In this neutrino oscillation scenario, assuming $|\\Delta m^2_{32}| = 2.4 \\times 10^{-3}$ $\\rm eV^2$, $\\sin^2 \\theta_{23} = 0.5$, $\\delta_{\\mathrm{CP}}=0$, and $\\Delta m^2_{32} >0$ ($\\Delta m^2_{32} <0$), a best-fit value of $\\sin^2 2 \\theta_{13}$ = $0.140^{+0.038}_{-0.032}$ ($0.170^{+0.045}_{-0.037}$) is obtained.

  16. Flavor distribution of UHE cosmic neutrino oscillations at neutrino telescopes

    Xing, Zhi-Zhong

    2009-04-01

    If the ultrahigh-energy (UHE) cosmic neutrinos produced from a distant astrophysical source can be measured at a km-size neutrino telescope such as the IceCube or KM3NeT, they will open a new window to understand the nature of flavor mixing and to probe possible new physics. Considering the conventional UHE cosmic neutrino source with the flavor ratio φe:φμ:φτ=1:2:0, I point out two sets of conditions for the flavor democracy φeT:φμT:φτT=1:1:1 to show up at neutrino telescopes: either θ13=0 and θ23=π/4 (CP invariance) or δ=±π/2 and θ23=π/4 (CP violation) in the standard parametrization of the 3×3 neutrino mixing matrix V. Allowing for slight μ-τ symmetry breaking effects characterized by Δ∈[-0.1,+0.1], I find φeT:φμT:φτT=(1-2Δ):(1+Δ):(1+Δ) as a good approximation. Another possibility to constrain Δ is to detect the ν flux of E≈6.3PeV via the Glashow resonance channel νe→W→anything. I also give some brief comments on (1) possible non-unitarity of V in the seesaw framework and its effects on the flavor distribution at neutrino telescopes and (2) a generic description and determination of the cosmic neutrino flavor composition at distant astrophysical sources.

  17. RENO: An Experiment for Neutrino Oscillation Parameter theta_13 Using Reactor Neutrinos at Yonggwang

    RENO Collaboration; Ahn, J. K.

    2010-01-01

    The RENO experiment is a short baseline neutrino experiment in Korea aiming to measure the neutrino mixing angle theta_13 or set limit to sin^2(2 theta_13) less than 0.02. This document describes physics goals, experimental site, detector design, scintillator, electronics, calibration, simulation, and physics reach.

  18. Obtaining nonvanishing $\\theta_{13}$ with constrained neutrino Yukawa matrix and implications for flavor model buildings

    Zhao, Ya

    2016-01-01

    Assuming a diagonal Majorana neutrino mass matrix, we investigate the neutrino Yukawa textures which lead to a non-zero reactor mixing angle $\\theta_{13}$. The neutrino effective coupling matrix $\\kappa^{eff}$ is pre-diagonalized by a constant mixing pattern $V_{\

  19. BEST sensitivity to O(1) eV sterile neutrino

    Barinov, Vladislav; Gorbunov, Dmitry; Ibragimova, Tatiana

    2016-01-01

    Numerous anomalous results in neutrino oscillation experiments can be attributed to interference of ~1 eV sterile neutrino. The specially designed to fully explore the Gallium anomaly Baksan Experiment on Sterile Transitions (BEST) starts next year. We investigate the sensitivity of BEST in searches for sterile neutrino mixed with electron neutrino. Then, performing the combined analysis of all the Gallium experiments (SAGE, GALLEX, BEST) we find the regions in model parameter space (sterile neutrino mass and mixing angle), which will be excluded if BEST agrees with no sterile neutrino hypothesis. For the opposite case, if BEST observes the signal as it follows from the sterile neutrino explanation of the Gallium (SAGE and GALLEX) anomaly, we show how BEST will improve upon the present estimates of the model parameters.

  20. Muon neutrino disappearance at MINOS

    Armstrong, R [Indiana Univ., Bloomington, IN (United States)

    2009-08-01

    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 Δm322 = 2.45+0.12-0.12 x 10-3 eV2 and sin232) = 1.00-0.04+0.00 (> 0.90 at 90% confidence level).

  1. Muon neutrino disappearance at MINOS

    Armstrong, R.; /Indiana U.

    2009-08-01

    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).

  2. The Borexino Solar Neutrino Experiment And Its Scintillator Containment Vessel

    Cadonati, L

    2001-01-01

    Thirty years ago, the first solar neutrino detector proved fusion reactions power the Sun. However, the total rate detected in this and all subsequent solar neutrino experiments is consistently two to three times lower than predicted by the Standard Solar Model. Current experiments seek to explain this “solar neutrino puzzle” through non-standard particle properties, like neutrino mass and flavor mixing, within the context of the MSW theory. The detection of the monoenergetic 7Be solar neutrino is the missing clue for the solution of the solar neutrino problem; this constitutes the main physics goal of Borexino, a real- time, high-statistics solar neutrino detector located under the Gran Sasso mountain, in Italy. In the first part of this thesis, I present a Monte Carlo study of the expected performance of Borexino, with simulations of the neutrino rate, the external y background and the α/β/γ activity in the scintillator. The Standard Solar Model predicts a so...

  3. Phenomenology of neutrino oscillations at the neutrino factory

    Tang, Jian

    2011-12-19

    We consider the prospects for a neutrino factory measuring mixing angles, the CP violating phase and mass-squared differences by detecting wrong-charge muons arising from the chain {mu}{sup +} {yields} {nu}{sub e} {yields} {nu}{sub {mu}} {yields} {mu}{sup -} and the right-charge muons coming from the chain {mu}{sup +} {yields} anti {nu}{sub {mu}} {yields} anti {nu}{sub {mu}} {yields} {mu}{sup -} (similar to {mu}{sup -} chains), where {nu}{sub e} {yields} {nu}{sub {mu}} and anti {nu}{sub {mu}} {yields} anti {nu}{sub {mu}} are neutrino oscillation channels through a long baseline. First, we study physics with near detectors and consider the treatment of systematic errors including cross section errors, flux errors, and background uncertainties. We illustrate for which measurements near detectors are required, discuss how many are needed, and what the role of the flux monitoring is. We demonstrate that near detectors are mandatory for the leading atmospheric parameter measurements if the neutrino factory has only one baseline, whereas systematic errors partially cancel if the neutrino factory complex includes the magic baseline. Second, we perform the baseline and energy optimization of the neutrino factory including the latest simulation results from the magnetized iron neutrino detector (MIND). We also consider the impact of {tau} decays, generated by appearance channels {nu}{sub {mu}} {yields} {nu}{sub {tau}} and {nu}{sub e} {yields} {nu}{sub {tau}}, on the discovery reaches of the mass orderings, the leptonic CP violation, and the non-zero {theta}{sub 13}, which we find to be negligible for the considered detector. Third, we make a comparison of a high energy neutrino factory to a low energy neutrino factory and find that they are just two versions of the same experiment optimized for different regions of the parameter space. In addition, we briefly comment on whether it is useful to build the bi-magic baseline at the low energy neutrino factory. Finally, the

  4. Measuring Atmospheric Neutrino Oscillations with Neutrino Telescopes

    Albuquerque, Ivone F. M.; Smoot, George F.

    2001-01-01

    Neutrino telescopes with large detection volumes can demonstrate that the current indications of neutrino oscillation are correct or if a better description can be achieved with non-standard alternatives. Observations of contained muons produced by atmospheric neutrinos can better constrain the allowed region for oscillations or determine the relevant parameters of non-standard models. We analyze the possibility of neutrino telescopes measuring atmospheric neutrino oscillations. We suggest ad...

  5. Neutrino Data and Neutrino-Antineutrino Transition

    Alexeyev, E N

    2005-01-01

    A problem, whether a neutrino-antineutrino transition could be responsible for the muon neutrino deficit found in underground experiments (Super-Kamiokande, MACRO, Soudan 2) and in the accelerator long-baseline K2K experiment, is discussed in this paper. The intention of the work is not consideration of concrete models for muon neutrino-antineutrino transition but a desire to attract an attention to another possibility of understanding the nature of the measured muon neutrino deficit in neutrino experiments.

  6. Liouville equations for neutrino distribution matrices

    Cardall, Christian Y

    2007-01-01

    The classical notion of a single-particle scalar distribution function or phase space density can be generalized to a matrix in order to accommodate superpositions of states of discrete quantum numbers, such as neutrino mass/flavor. Such a `neutrino distribution matrix' is thus an appropriate construct to describe a neutrino gas that may vary in space as well as time and in which flavor mixing competes with collisions. The Liouville equations obeyed by neutrino distribution matrices, including the spatial derivative and vacuum flavor mixing terms, can be explicitly but elegantly derived in two new ways: from a covariant version of the familiar simple model of flavor mixing, and from the Klein-Gordon equations satisfied by a quantum `density function' (mean value of paired quantum field operators). Associated with the latter derivation is a case study in how the joint position/momentum dependence of a classical gas (albeit with Fermi statistics) emerges from a formalism built on quantum fields.

  7. Constraining the lightest neutrino mass and mee from general lepton mass matrices

    Samandeep Sharma; Gulsheen Ahuja; Manmohan Gupta

    2016-02-01

    Despite spectacular advances in fixing the neutrino mass and mixing parameters through various neutrino oscillation experiments, we still have little knowledge about the magnitudes of some vital parameters in the neutrino sector such as the absolute neutrino mass scale, effective Majorana mass mee measured in neutrinoless double beta decay. In this context, the present work aims to make an attempt to obtain some bounds for mee and the lightest neutrino mass using fairly general lepton mass matrices in the Standard Model.

  8. A Combined View of Sterile-Neutrino Constraints from CMB and Neutrino Oscillation Measurements

    Bridle, Sarah; Evans, Justin; Fernandez, Susana; Guzowski, Pawel; Soldner-Rembold, Stefan

    2016-01-01

    We perform a comparative analysis of constraints on sterile neutrinos from the Planck experiment and from current and future neutrino oscillation experiments (MINOS, IceCube, SBN). For the first time, we express the Planck constraints on $N_{\\rm eff}$ and $m_{\\rm eff}^{\\rm sterile}$ from the Cosmic Microwave Background in the parameter space used by oscillation experiments using both mass-squared differences and mixing angles. In a model with a single sterile neutrino species and using standard assumptions, we find that the Planck data and the oscillation experiments measuring muon-neutrino disappearance have similar sensitivity.

  9. Long Baseline Neutrino Beams and Large Detectors

    Samios,N.P.

    2008-10-27

    It is amazing to acknowledge that in roughly 70 years from when the existence of the neutrino was postulated, we are now contemplating investigating the mysteries of this particle (or particles) requiring and utilizing detectors of 300 ktons , distances of 1,000-2,000 kilometers, beam intensities of megawatts and underground depth of 5,000 feet. This evolution has evolved slowly, from the experimental discovery of the neutrino in 1956, to the demonstration that there were two neutrinos in 1962 and three and only three by 1991. The great excitement occurred in the 2000's coming from the study of solar and atmospheric neutrinos in which neutrinos were observed to oscillate and therefore have mass. Although the absolute mass of any of the neutrinos has yet to be determined (the upper limit is less than I electron volt) the difference in this square of these masses has been measured, yielding a value of (2.3 {+-} .2) 10{sup -3} ev{sup 2} for atmospheric neutrinos and (7.6 {+-} .2) 10{sup -5} ev{sup 2} for solar neutrinos. In addition their mixing angles were found to be 45{sup o} for atmospheric neutrinos and 34{sup o} for solar neutrinos. This present state of knowledge on neutrinos is pictorially displayed in Fig. 1. Of course, mixing between flavors had already been observed in the quark sector as exemplified by the Cabbibo-Kobayashi-Meskawa Matrix. It was therefore natural to extend this formalism to the lepton sector involving unitary 3 x 3 matrices and one CP violating phase. This is shown in Fig. 2 for the two sectors, quark and leptons including the Jarlskog invariant (J).

  10. Neutrino cave

    1977-01-01

    Here the end of the underground decay tunnel, its window and beam stopper. On the left one sees the end of the last quadrupole of the neutrino narrow-band beam, and the detectors measuring the beam profile. Further downstream one sees two Beam Current Transformers (BCT, see photo 7801005) measuring the beam intensity, and a Cerenkov counter.

  11. Neutrino horn

    1967-01-01

    View of the new neutrino horn installed in its blockhouse from the target end. Protons pass through the 2mm hole in the centre of the small fluorescent screen, hitting the target immediately behind it. The circular tubes carry pressurized cooling water.

  12. Neutrino experiments

    After participating in a several experiments near the reactor at Bugey, at distances from 15 to 100 m from the reactor the laboratory joined a collaboration for search of effect of neutrino oscillations at longer distances (1 km) from the neutrinos' point of origin. The zone covered by this experiment raises a particular interest because the results of several underground experiments on the atmospheric neutrinos indicated that oscillation could appear in this zone. The Chooz collaboration, reported here, joined three American universities (Philadelphia, New Mexico and Irvine), two Italian universities (Pisa and Trieste), the Kurchatov Institute in Moscow and two French laboratories (the LAPP in Annecy and the College de France). The first data have been recorded during the autumn of 1996 prior to the commissioning of the reactors (2 x 4200 MWth), to measure the background noise. The detector is a target of 6 t liquid scintillator doped with Gd, sunk in 120 t non-doped liquid scintillator separated by thin transparent wall. The target is viewed by 192 photomultipliers. The scintillator liquids are carried up to the detector and then to the exterior tanks by a tunnel of 200 m length and a height gradient of 15 m. The fragility of the detector imposes a simultaneous filling of its components, with an accuracy of the order of 1 cm. A 200 MHz sampling system of the photomultiplier pulses signing the neutrino interaction was developed in order to obtain simultaneously information on the pulse-height, timing and shape. This experiment could serve as a prototype for heavier experiments conceived in US, in Russia at Rovno and Krasnoyarsk, and in France, at 15 km from the Perry reactor, at 500 m underground. Still more ambitious is the Japan project at Kamioka, at 160 m distance from a nuclear reactor. The experiment at Perry will push the electron neutrino upper mass estimates down to 0.01 eV

  13. The solar neutrino puzzle: Mapping a solution

    Remarkable progress has been made over the past 30 years in understanding the flux of neutrinos coming from the sun. The so-called 'solar neutrino puzzle', whereby the total number of electron neutrinos from the sun does not match the expected total neutrino yield can be now understood in the context of neutrino flavor transformations. The Sudbury Neutrino Observatory has contributed to understanding the solar neutrino problem by measuring both the electron and non-electron components of the solar neutrino flux. The Sudbury Neutrino Observatory is a 1000 T D2O Cerenkov detector that is sensitive to 8B neutrinos produced in the sun. By using the energy, radius, and direction with respect to the sun, the SNO experiment can separately determine the rates of the charged current, neutral current and electron scattering reactions of neutrinos on deuterium. Assuming an undistorted 8B spectrum, the ve component of the 8B solar flux is φe 1.76-0.05+0.05(stat.)-0.09+0.09 (syst.) x 106 cm-2s-1 based on events with a measured kinetic energy above 5 MeV. The non-ve component is φμτ 3.41-0.45+0.45(stat.)-0.45+0.48 (syst.) x 106 cm-2s-1, 5.3σ greater than zero, providing strong evidence for solar ve flavor transformation. The total flux measured with the NC reaction is φNC = 5.09-0.43+0.44(stat.)-0.43+0.46 (syst.) x 106 cm-2s-1, consistent with the Standard Solar Model. A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the Large Mixing Angle (LMA) solution

  14. Resonant enhancement of flavor-changing neutrino interactions

    The resonant amplification of neutrino oscillations in the presence of flavor-changing neutrino interactions with matter is analyzed. It is shown that a significant μ-flavor conversion can take place even in the absence of neutrino mixing in vacuum. To account for the solar neutrino deficit, the strength of the new interactions should be ∼ 10-2GF and the resulting neutrino suppression and spectrum is similar to that in the ordinary MSW effect. I discuss some extensions of the standard model where these interactions can be present, taking into account the experimental constraints that arise mainly from the induced leptonic rare decays

  15. Muon Colliders and Neutrino Factories

    Kaplan, Daniel M

    2014-01-01

    Muon colliders and neutrino factories are attractive options for future facilities aimed at achieving the highest lepton-antilepton collision energies and precision measurements of Higgs boson and neutrino mixing matrix parameters. The facility performance and cost depend on how well a beam of muons can be cooled. Recent progress in muon cooling design studies and prototype tests nourishes the hope that such facilities could be built starting in the coming decade. The status of the key technologies and their various demonstration experiments is summarized. Prospects "post-P5" are also discussed.

  16. Neutrino Oscillations: Hierarchy Question

    Ernst, D J; Burroughs, H R; Escamilla-Roa, J; Latimer, D C

    2013-01-01

    The only experimentally observed phenomenon that lies outside the standard model of the electroweak interaction is neutrino oscillations. A way to try to unify the extensive neutrino oscillation data is to add a phenomenological mass term to the Lagrangian that is not diagonal in the flavor basis. The goal is then to understand the world's data in terms of the parameters of the mixing matrix and the differences between the squares of the masses of the neutrinos. An outstanding question is what is the correct ordering of the masses, the hierarchy question. We point out a broken symmetry relevant to this question, the symmetry of the simultaneous interchange of hierarchy and the sign of $\\theta_{13}$. We first present the results of an analysis of data that well determine the phenomenological parameters but are not sensitive to the hierarchy. We find $\\theta_{13} = 0.152\\pm 0.014$, $\\theta_{23} = 0.25^{+0.03}_{-0.05} \\pi$ and $\\Delta_{32} = 2.45\\pm 0.14 \\times 10^{-3}$ eV$^2$, results consistent with others. We...

  17. Expectation values of flavor-neutrino numbers with respect to neutrino-source hadron states: Neutrino oscillations and decay probabilities

    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 the 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. In addition, it is shown that the oscillation formulas, similar to the usual ones, are derived irrespectively of the details of neutrino-producing processes. The derived oscillation formulas are regarded as being the same in form as the usually adopted ones, except for some simple distinctions

  18. Measuring neutrino mass without neutrinos!

    Peach, Kenneth J

    2004-01-01

    Neutrinoless double beta decay offers the most precise (if challenging) way of measuring the absolute mass of the neutrino. Particle Physics met at the Rutherford Appleton Laboratory last autumn to discuss wether the UK should take a lead in setting up such an experiment

  19. Neutrino beams and experiments

    After a brief review of the early history of neutrino experiments, the principle of neutrino beams at proton accelerators is described and a survey of neutrino experiments since 1963 is given. ((orig.))

  20. Can a non-unitary effect be prominent In neutrino oscillation measurements?

    L(U) Lei; WANG Wen-Yu; XIONG zhao-Hua

    2010-01-01

    Subject to neutrino experiments, the mixing matrix of ordinary neutrinos can still have small vi-olation from unitarity. We introduce a quasi-unitary matrix to interpret this violation and propose a natural scheme to parameterize it. A quasi-unitary factor △QF is defined to be measured in neutrino oscillation exper-iments and the numerical results show that the improvement in experimental precision may help us figure out the secret of neutrino mixing.

  1. An Appraisal of Muon Neutrino Disappearance at Short Baseline Neutrino Beams

    Stanco, Luca; Longhin, Andrea; Bertolin, Alessandro; Laveder, Marco

    2013-01-01

    Neutrino physics is nowadays receiving more and more attention as a possible source of information for the long standing problem of new Physics beyond the Standard Model. The recent measurements of the third mixing angle $\\theta_{13}$ in the standard mixing oscillation scenario encourage to pursue the still missing results on the leptonic CP violation and the absolute neutrino masses. However, several puzzling and incomplete measurements are in place which deserve an exhaustive evaluation and study. We will report about the present situation of the muon disappearance measurements at small $L/E$ in the context of the current CERN project to revitalize the neutrino field in Europe and the search for sterile neutrinos. We will then illustrate the achievements that a double muon spectrometer can attain in terms of discovery of new neutrino states, performing a newly developed analysis.

  2. Updated determination of the solar neutrino fluxes from solar neutrino data

    Bergstrom, Johannes; Maltoni, Michele; Pena-Garay, Carlos; Serenelli, Aldo M; Song, Ningqiang

    2016-01-01

    We present an update of the determination of the solar neutrino fluxes from a global analysis of the solar and terrestrial neutrino data in the framework of three-neutrino mixing. Using a Bayesian analysis we reconstruct the posterior probability distribution function for the eight normalization parameters of the solar neutrino fluxes plus the relevant masses and mixing, with and without imposing the luminosity constraint. We then use these results to compare the description provided by different Standard Solar Models. Our results show that, at present, both models with low and high metallicity can describe the data with equivalent statistical agreement. We also argue that even with the present experimental precision the solar neutrino data have the potential to improve the accuracy of the solar model predictions.

  3. A measurement of neutrino oscillations with muon neutrinos in the MINOS experiment

    Coleman, Stephen James [College of William and Mary, Williamsburg, VA (United States)

    2011-05-01

    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 Δm232 = (2.32-0.08+0.12) x 10-3 eV2/c4 and the mixing angle sin2(2θ32) > 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 7.2σ and the neutrino quantum decoherence hypothesis is disfavored at 9.0σ.

  4. Experimental Neutrino Physics

    Zuber, K.

    2008-01-01

    It's been a remarkable decade in neutrino physics. Ten years ago this summer, at the 1998 neutrino conference in Takayama, the Super-Kamiokande collaboration reported the observation of neutrinos changing flavor, thereby establishing the existence of neutrino mass. A few years later, the SNO experiment solved the long-standing solar neutrino problem demonstrating that it too was due to neutrino oscillation. Just a few years after that, these effects were confirmed and the oscillation paramete...

  5. The Simplest Neutrino Mass Matrix

    Harrison, P F

    2004-01-01

    We motivate the simplest ansatz for the neutrino mass matrix consistent with the data from neutrino oscillation experiments, and admitting CP violation. It has only two free parameters: an arbitrary mass-scale and a small dimensionless ratio. This mass matrix exhibits two symmetries, Democracy and Mutativity, which respectively ensure trimaximal mixing of the |nu_2> mass eigenstate, and mixing parameter values |theta_{23}|=45 degrees and |delta|=90 degrees, consistent with bimaximal mixing of the |nu_3> mass eigenstate. A third constraint relates the smallness of |U_{e3}|^2 to that of the mass-squared difference ratio, Delta m^2_sol/Delta m^2_atm, yielding the prediction sin(theta_{13})=sqrt{2 Delta m^2_sol/3 Delta m^2_atm} ~ 0.13 +- 0.03.

  6. Nuclear effects in neutrino-nucleus DIS

    Hirai, M; Saitô, K

    2009-01-01

    We explain the current status of nuclear parton distribution functions in connection with neutrino-nucleus interactions. Neutrino deep inelastic scattering (DIS) measurements have been done for heavy nuclear targets such as iron and lead. In order to extract structure functions of the nucleon, one needs to remove nuclear effects from the data. However, recent studies indicate that there are inconsistencies in nuclear modifications between charged-lepton and neutrino scattering measurements. Nuclear medium effects could be also an origin for the NuTeV anomaly in the weak-mixing angle. In addition, the modifications could affect neutrino-oscillation experiments because some DIS events of neutrino-oxygen nucleus interactions are contained. On the other hand, the nuclear medium effects themselves are interesting and important for describing nuclei in terms of quark and gluon degrees of freedom.

  7. Investigation of Neutrino Properties with Bolometric Detectors

    Heeger, Karsten M [University of Wisconsin & Yale University

    2014-11-01

    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 (0νββ) is the only known mechanism to test whether neutrinos are their own antiparticles. The observation of 0νββ 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 0νββ 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.

  8. Neutrinos: Theory and Phenomenology

    Parke, Stephen J

    2013-01-01

    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.

  9. Neutrinos: Theory and Phenomenology

    Parke, Stephen

    2013-10-22

    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.

  10. Neutrinos: theory and phenomenology

    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. (paper)

  11. Resolving the reactor neutrino anomaly with the KATRIN neutrino experiment

    Formaggio, J. A.; Barrett, J.

    2011-11-01

    The KArlsruhe TRItium Neutrino experiment (KATRIN) combines an ultra-luminous molecular tritium source with an integrating high-resolution spectrometer to gain sensitivity to the absolute mass scale of neutrinos. The projected sensitivity of the experiment on the electron neutrino mass is 200 meV at 90% C.L. With such unprecedented resolution, the experiment is also sensitive to physics beyond the Standard Model, particularly to the existence of additional sterile neutrinos at the eV mass scale. A recent analysis of available reactor data appears to favor the existence of such a sterile neutrino with a mass splitting of | Δmsterile | 2 ⩾ 1.5eV2 and mixing strength of sin2 2θsterile = 0.17 ± 0.08 at 95% C.L. Upcoming tritium beta decay experiments should be able to rule out or confirm the presence of the new phenomenon for a substantial fraction of the allowed parameter space.

  12. The one loop corrections to the neutrino masses in BLMSSM

    Zhao, Shu-Min; Feng, Tai-Fu; Dong, Xing-Xing; Zhang, Hai-Bin; Ning, Guo-Zhu; Guo, Tao

    2016-09-01

    The neutrino masses and mixings are studied in the model which is the supersymmetric extension of the standard model with local gauged baryon and lepton numbers (BLMSSM). At tree level the neutrinos can obtain tiny masses through the See-Saw mechanism in the BLMSSM. The one-loop corrections to the neutrino masses and mixings are important, and they are studied in this work with the mass insertion approximation. We study the numerical results and discuss the allowed parameter space of BLMSSM. It can contribute to study the neutrino masses and to explore the new physics beyond the standard model (SM).

  13. The one loop corrections to the neutrino masses in BLMSSM

    Zhao, Shu-Min; Dong, Xing-Xing; Zhang, Hai-Bin; Ning, Guo-Zhu; Tao-Guo,

    2016-01-01

    The neutrino masses and mixing are studied in the model which is the supersymmetric extension of the standard model with local gauged baryon and lepton numbers(BLMSSM). BLMSSM includes the See-Saw mechanism for neutrinos at tree level. The one-loop corrections to the neutrino masses and mixing are important, which are studied in this work with the mass insertion approximation. The numerical analysis shows the relations between the experimental data and the BLMSSM parameters. It can contribute to the study of neutrino masses and to explore the new physics beyond the standard model(SM).

  14. The one loop corrections to the neutrino masses in BLMSSM

    Shu-Min Zhao

    2016-09-01

    Full Text Available The neutrino masses and mixings are studied in the model which is the supersymmetric extension of the standard model with local gauged baryon and lepton numbers (BLMSSM. At tree level the neutrinos can obtain tiny masses through the See-Saw mechanism in the BLMSSM. The one-loop corrections to the neutrino masses and mixings are important, and they are studied in this work with the mass insertion approximation. We study the numerical results and discuss the allowed parameter space of BLMSSM. It can contribute to study the neutrino masses and to explore the new physics beyond the standard model (SM.

  15. Supernova neutrinos

    In the first part of his in-depth article on the 1987 supernova, David Schramm of the University of Chicago and the NASA/Fermilab Astrophysics Centre reviewed the background to supernovae, the composition of massive stars and the optical history of SN 1987A, and speculated on what the 1987 remnant might be. In such a Type II supernova, gravitational pressure crushes the atoms of the star's interior producing neutron matter, or even a black hole, and releasing an intense burst of neutrinos. 1987 was the first time that physicists were equipped (but not entirely ready!) to intercept these particles, and in the second part of his article, David Schramm covers the remarkable new insights from the science of supernova neutrino astronomy, born on 23 February 1987

  16. Study on the Neutrino Oscillation with a Next Generation Medium-Baseline Reactor Experiment

    For over fifty years, reactor experiments have played an important role in neutrino physics, in both discoveries and precision measurements. One of the methods to verify the existence of neutrino is the observation of neutrino oscillation phenomena. Electron antineutrinos emitted from a reactor provide the measurement of the small mixing angle θ13, providing rich programs of neutrino properties, detector development, nuclear monitoring, and application. Using reactor neutrinos, future reactor neutrino experiments, more precise measurements of θ12,Δm122, and mass hierarchy will be explored. The precise measurement of θ13 would be crucial for measuring the CP violation parameters at accelerators. Therefore, reactor neutrino physics will assist in the complete understanding of the fundamental nature and implications of neutrino masses and mixing. In this paper, we investigated several characteristics of RENO-50, which is a future medium-baseline reactor neutrino oscillation experiment, by using the GloBES simulation package

  17. CP-phase effects on the effective neutrino mass $m_{ee}$ in the case of quasi-degenerate neutrinos

    Maalampi, J.; Riittinen, J.

    2009-01-01

    We study the possibility that the three mass states of the ordinary active neutrinos actually split into pairs of quasi-degenerate states, with $\\Delta m^2_{kk'} \\sim 10^{-12}$ eV$^2$ or less, as a result of mixing of active neutrinos with sterile neutrinos. Although these quasi-degenerate pairs will look in laboratory experiment identical to single active states, the CP phase factors associated with active-sterile mixing might cause cancellations in the effective electron neutrino mass $m_{e...

  18. PREFACE: Neutrino physics at spallation neutron sources

    Avignone, F. T.; Chatterjee, L.; Efremenko, Y. V.; Strayer, M.

    2003-11-01

    Unique because of their super-light masses and tiny interaction cross sections, neutrinos combine fundamental physics on the scale of the miniscule with macroscopic physics on the scale of the cosmos. Starting from the ignition of the primal p-p chain of stellar and solar fusion reactions that signal star-birth, these elementary leptons (neutrinos) are also critical players in the life-cycles and explosive deaths of massive stars and the production and disbursement of heavy elements. Stepping beyond their importance in solar, stellar and supernova astrophysics, neutrino interactions and properties influence the evolution, dynamics and symmetries of the cosmos as a whole. Further, they serve as valuable probes of its material content at various levels of structure from atoms and nuclei to valence and sea quarks. In the light of the multitude of physics phenomena that neutrinos influence, it is imperative to enhance our understanding of neutrino interactions and properties to the maximum. This is accentuated by the recent evidence of finite neutrino mass and flavour mixing between generations that reverberates on the plethora of physics that neutrinos influence. Laboratory experiments using intense neutrino fluxes would allow precision measurements and determination of important neutrino reaction rates. These can then complement atmospheric, solar and reactor experiments that have enriched so valuably our understanding of the neutrino and its repertoire of physics applications. In particular, intermediate energy neutrino experiments can provide critical information on stellar and solar astrophysical processes, along with advancing our knowledge of nuclear structure, sub-nuclear physics and fundamental symmetries. So where should we look for such intense neutrino sources? Spallation neutron facilities by their design are sources of intense neutrino pulses that are produced as a by-product of neutron spallation. These neutrino sources could serve as unique laboratories

  19. Working group report: Neutrino and astroparticle physics

    Srubabati Goswami; Raghavan Rangarajan; K Agashe; A Bandyopadhyay; K Bhattacharya; B Brahmachari; C Burgess; E J Chun; D Choudhury; P K Das; A Dighe; A Godbole; S Goswami; N Gupta; M Kaplinghat; D Indumathi; J Forshaw; Y Y Keum; B Layek; D Majumdar; N Mahajan; P Mehta; R N Mohapatra; N Mondal; S More; N Nir; S Pakvasa; M K Parida; M Ravikumar; G Rajasekaran; P Ramadevi; R Rangarajan; S D Rindani; D P Roy; P Roy; N Sahu; A samanta; Y Shadmi; A M Srivastava; S Uma Sankar; R Vaidya; U Yajnik

    2004-12-01

    This is the report of neutrino and astroparticle physics working group at WHEPP-8. We present the discussions carried out during the workshop on selected topics in the above fields and also indicate progress made subsequently. The neutrino physics subgroup studied the possibilities of constraining neutrino masses, mixing and CPT violation in lepton sector from future experiments. Neutrino mass models in the context of Abelian horizontal symmetries, warped extra dimensions and in the presence of triplet Higgs were studied. Effect of threshold corrections on radiative magnification of mixing angles was investigated. The astroparticle physics subgroup focused on how various particle physics inputs affect the CMBR fluctuation spectrum, and on brane cosmology. This report also contains an introduction on how to use the publicly available code CMBFAST to calculate the CMBR fluctuations.

  20. Future reactor neutrino oscillation experiments at Krasnoyarsk

    Recent studies of atmospheric neutrinos and the results from CHOOZ and Palo-Verde experiment call for new and more sensitive searches for neutrino oscillations at reactors. The main goal of the project considered here is to look for very small mixing angle oscillations of electron neutrinos in the atmospheric neutrino mass parameter region around Δm2 ∼ 3 x 10-3eV2 and to define the element Ue3 of the neutrino mixing matrix (Ue3 is the contribution of the mass-3 state to the electron neutrino flavor state). The practical goal of the project is to decrease, relative to the CHOOZ, the statistic and systematic errors as much as possible. To achieve this we plan to use two identical antineutrino detectors each with a ∼ 50-ton liquid scintillator target located at ∼1100 m and ∼250 m from the underground reactor (∼ 600 mwe). Much attention is given to the detector calibration and monitoring procedures. As a first step we consider two much smaller pilot detectors each of ∼ a 3 ton target mass stationed at ∼20 m and 35-60 m from the reactor. The goals of this first stage are: (i) to accumulate necessary experience and (ii) to investigate with electron neutrinos the LSND mass parameter region