Model of neutrino effective masses
Dinh Nguyen Dinh; Nguyen Thi Hong Van; Nguyen Anh Ky; Phi Quang Van
2006-10-01
It is shown that an effective (nonrenormalizable) coupling of lepton multiplets to scalar triplets in the 331 model with sterile/exotic neutrinos, can be a good way for generating neutrino masses of different types. The method is simple and avoids radiative/loop calculations which, sometimes, are long and complicated. Basing on some astrophysical arguments it is also stated that the scale of SU(3){sub L} symmetry breaking is at TeV scale, in agreement with earlier investigations. Or equivalently, starting from this symmetry breaking scale we could have sterile/exotic neutrinos with mass of a few keV's which could be used to explain several astrophysical and cosmological puzzles, such as the dark matter, the fast motion of the observed pulsars, the re-ionization of the Universe, etc.
Predictive models of radiative neutrino masses
NASA Astrophysics Data System (ADS)
Julio, J.
2016-06-01
We discuss two models of radiative neutrino mass generation. The first model features one-loop Zee model with Z4 symmetry. The second model is the two-loop neutrino mass model with singly- and doubly-charged scalars. These two models fit neutrino oscillation data well and predict some interesting rates for lepton flavor violation processes.
Predictive models of radiative neutrino masses
Julio, J.
2016-06-21
We discuss two models of radiative neutrino mass generation. The first model features one–loop Zee model with Z{sub 4} symmetry. The second model is the two–loop neutrino mass model with singly- and doubly-charged scalars. These two models fit neutrino oscillation data well and predict some interesting rates for lepton flavor violation processes.
Radiative neutrino mass model with degenerate right-handed neutrinos
NASA Astrophysics Data System (ADS)
Kashiwase, Shoichi; Suematsu, Daijiro
2016-03-01
The radiative neutrino mass model can relate neutrino masses and dark matter at a TeV scale. If we apply this model to thermal leptogenesis, we need to consider resonant leptogenesis at that scale. It requires both finely degenerate masses for the right-handed neutrinos and a tiny neutrino Yukawa coupling. We propose an extension of the model with a U(1) gauge symmetry, in which these conditions are shown to be simultaneously realized through a TeV scale symmetry breaking. Moreover, this extension can bring about a small quartic scalar coupling between the Higgs doublet scalar and an inert doublet scalar which characterizes the radiative neutrino mass generation. It also is the origin of the Z_2 symmetry which guarantees the stability of dark matter. Several assumptions which are independently supposed in the original model are closely connected through this extension.
Neutrino mass models and CP violation
Joshipura, Anjan S.
2011-10-06
Theoretical ideas on the origin of (a) neutrino masses (b) neutrino mass hierarchies and (c) leptonic mixing angles are reviewed. Topics discussed include (1) symmetries of neutrino mass matrix and their origin (2) ways to understand the observed patterns of leptonic mixing angles and (3)unified description of neutrino masses and mixing angles in grand unified theories.
New model for the neutrino mass matrix
NASA Astrophysics Data System (ADS)
Lavoura, L.
2000-11-01
I suggest a model based on a softly broken symmetry Le-Lμ-Lτ and on Babu's mechanism for the two-loop radiative generation of neutrino masses. The model predicts that one of the physical neutrinos (ν3) is massless and that its component along the νe direction (Ue3) is zero. Moreover, if the soft-breaking term is assumed to be very small, then the vacuum oscillations of νe have almost maximal amplitude and solve the solar-neutrino problem. New scalars are predicted in the 10 TeV energy range, and a breakdown of e-μ-τ universality should not be far from existing experimental bounds.
Supersymmetric model with Dirac neutrino masses
Marshall, Gardner; McCaskey, Mathew; Sher, Marc
2010-03-01
New models have recently been proposed in which a second Higgs doublet couples only to the lepton doublets and right-handed neutrinos, yielding Dirac neutrino masses. The vacuum value of this second 'nu-Higgs' doublet is made very small by means of a very softly-broken Z{sub 2} or U(1) symmetry. The latter is technically natural and avoids fine-tuning and very light scalars. We consider a supersymmetric version of this model, in which two additional doublets are added to the minimal supersymmetric standard model (MSSM). If kinematically allowed, the decay of the heavy MSSM scalar into charged nu-Higgs scalars will yield dilepton events which can be separated from the W-pair background. In addition, the nu-Higgsinos can lead to very dramatic tetralepton, pentalepton, and hexalepton events which have negligible background and can be detected at the LHC and the Tevatron.
Predictive minimal model for neutrino masses and mixings
NASA Astrophysics Data System (ADS)
Stech, Berthold
2000-11-01
A model is considered in which the scale of the heavy singlet neutrinos is a few orders of magnitude below the grand unification scale and where right-handed vector bosons still play a negligible role. In a basis with diagonal up-quark and Dirac-neutrino mass matrices it is assumed that the heavy neutrino mass matrix has only zero elements in its diagonal, in analogy with the light neutrino mass matrix in the Zee model. Connecting then the remaining matrix elements with the small parameter describing the hierarchy of quark masses and mixings and by assuming commutativity of the charged lepton with the down-quark mass matrix, the calculation of all neutrino properties can be performed in terms of the two mass differences relevant for atmospheric and solar neutrino oscillations. CP violation is directly related to CP violation in the quark sector.
Robertson, R.G.H.
1992-01-01
Despite intensive experimental work since the neutrino's existence was proposed by Pauli 60 years ago, and its first observation by Reines and Cowan almost 40 years ago, the neutrino's fundamental properties remain elusive. Among those properties are the masses of the three known flavors, properties under charge conjugation, parity and time-reversal, and static and dynamic electromagnetic moments. Mass is perhaps the most fundamental, as it constrains the other properties. The present status of the search for neutrino mass is briefly reviewed.
Renormalization of a two-loop neutrino mass model
Babu, K. S.; Julio, J.
2014-01-01
We analyze the renormalization group structure of a radiative neutrino mass model consisting of a singly charged and a doubly charged scalar fields. Small Majorana neutrino masses are generated by the exchange of these scalars via two-loop diagrams. We derive boundedness conditions for the Higgs potential and show how they can be satisfied to energies up to the Planck scale. Combining boundedness and perturbativity constraints with neutrino oscillation phenomenology, new limits on the masses and couplings of the charged scalars are derived. These in turn lead to lower limits on the branching ratios for certain lepton flavor violating (LFV) processes such as μ→eγ, μ→3e and μ – e conversion in nuclei. Improved LFV measurements could test the model, especially in the case of inverted neutrino mass hierarchy where these are more prominent.
Model independent explorations of Majorana neutrino mass origins
NASA Astrophysics Data System (ADS)
Jenkins, James Phearl, Jr.
The recent observation of nonzero neutrino mass is the first concrete indication of physics beyond the Standard Model. Their properties, unique among the other fermions, leads naturally to the idea of a Majorana neutrino mass term. Despite the strong theoretical prejudice toward this concept, it must be tested experimentally. This is indeed possible in the context of next generation experiments. Unfortunately, the scale of neutrino mass generation may be too large to explore directly, but useful information may still be extracted from independent experimental channels. Here I survey various model independent probes of Majorana neutrino mass origins. A brief introduction to the concepts relevant to the analysis is followed by a discussion of the physical ranges of neutrino mass and mixing parameters within the context of standard and non-standard interactions. Armed with this, I move on to systematically analyze the properties of radiatively generated neutrino masses induced by nonrenormalizable lepton number violating effective operators of mass dimensions five through eleven. By fitting these to the observed light mass scale, I extract predictions for neutrino mixing as well as neutrinoless double beta decay, rare meson/tau decays and collider phenomenology. I find that many such models are already constrained by current data and many more will be probed in the near future. I then move on demonstrate the utility of a low scale see saw mechanism via a viable 3+2+1 sterile neutrino model that satisfies all oscillation data as well as solves problems associated with supernova kicks and heavy element nucleosynthesis. From this I extract predictions for tritium and neutrinoless double beta decay searches. This is supplemented throughout by descriptions of practical limitations in addition to suggestions for future work.
NASA Astrophysics Data System (ADS)
Capelli, Silvia; Di Bari, Pasquale
2013-04-01
Neutrino oscillation experiments firmly established non-vanishing neutrino masses, a result that can be regarded as a strong motivation to extend the Standard Model. In spite of being the lightest massive particles, neutrinos likely represent an important bridge to new physics at very high energies and offer new opportunities to address some of the current cosmological puzzles, such as the matter-antimatter asymmetry of the Universe and Dark Matter. In this context, the determination of the absolute neutrino mass scale is a key issue within modern High Energy Physics. The talks in this parallel session well describe the current exciting experimental activity aiming to determining the absolute neutrino mass scale and offer an overview of a few models beyond the Standard Model that have been proposed in order to explain the neutrino masses giving a prediction for the absolute neutrino mass scale and solving the cosmological puzzles.
Unification of gauge couplings in radiative neutrino mass models
NASA Astrophysics Data System (ADS)
Hagedorn, Claudia; Ohlsson, Tommy; Riad, Stella; Schmidt, Michael A.
2016-09-01
We investigate the possibility of gauge coupling unification in various radiative neutrino mass models, which generate neutrino masses at one- and/or two-loop level. Renormalization group running of gauge couplings is performed analytically and numerically at one- and two-loop order, respectively. We study three representative classes of radiative neutrino mass models: (I) minimal ultraviolet completions of the dimension-7 Δ L = 2 operators which generate neutrino masses at one- and/or two-loop level without and with dark matter candidates, (II) models with dark matter which lead to neutrino masses at one-loop level and (III) models with particles in the adjoint representation of SU(3). In class (I), gauge couplings unify in a few models and adding dark matter amplifies the chances for unification. In class (II), about a quarter of the models admits gauge coupling unification. In class (III), none of the models leads to gauge coupling unification. Regarding the scale of unification, we find values between 1014 GeV and 1016 GeV for models belonging to class (I) without dark matter, whereas models in class (I) with dark matter as well as models of class (II) prefer values in the range 5·1010 - 5·1014 GeV.
The seesaw portal in testable models of neutrino masses
NASA Astrophysics Data System (ADS)
Caputo, A.; Hernández, P.; López-Pavón, J.; Salvado, J.
2017-06-01
A Standard Model extension with two Majorana neutrinos can explain the measured neutrino masses and mixings, and also account for the matter-antimatter asymmetry in a region of parameter space that could be testable in future experiments. The testability of the model relies to some extent on its minimality. In this paper we address the possibility that the model might be extended by extra generic new physics which we parametrize in terms of a low-energy effective theory. We consider the effects of the operators of the lowest dimensionality, d = 5, and evaluate the upper bounds on the coefficients so that the predictions of the minimal model are robust. One of the operators gives a new production mechanism for the heavy neutrinos at LHC via higgs decays. The higgs can decay to a pair of such neutrinos that, being long-lived, leave a powerful signal of two displaced vertices. We estimate the LHC reach to this process.
Radiative model of neutrino mass with neutrino interacting MeV dark matter
Arhrib, Abdesslam; Boehm, Céline; Ma, Ernest; Yuan, Tzu-Chiang
2016-04-26
We consider the radiative generation of neutrino mass through the interactions of neutrinos with MeV dark matter. We construct a realistic renormalizable model with one scalar doublet (in additional to the standard model doublet) and one complex singlet together with three light singlet Majorana fermions, all transforming under a dark U(1){sub D} symmetry which breaks softly to Z{sub 2}. We study in detail the scalar sector which supports this specific scenario and its rich phenomenology.
Models of Neutrino Masses: Anarchy versus Hierarchy
NASA Astrophysics Data System (ADS)
Altarelli, Guido; Feruglio, Ferruccio; Masina, Isabella
2003-01-01
We present a quantitative study of the ability of models with different levels of hierarchy to reproduce the solar neutrino solutions, in particular the LA solution. As a flexible testing ground we consider models based on SU(5) × U(1)F. In this context, we have made statistical simulations of models with different patterns from anarchy to various types of hierarchy: normal hierarchical models with and without automatic suppression of the 23 (sub)determinant and inverse hierarchy models. We find that, not only for the LOW or VO solutions, but even in the LA case, the hierarchical models have a significantly better success rate than those based on anarchy. The normal hierarchy and the inverse hierarchy models have comparable performances in models with see-saw dominance, while the inverse hierarchy models are particularly good in the no see-saw versions. As a possible distinction between these categories of models, the inverse hierarchy models favour a maximal solar mixing angle and their rate of success drops dramatically as the mixing angle decreases, while normal hierarchy models are far more stable in this respect.
Direct neutrino mass measurements
NASA Astrophysics Data System (ADS)
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.
False vacuum in the supersymmetric mass varying neutrinos model
Takahashi, Ryo; Tanimoto, Morimitsu
2008-02-15
We present detailed analyses of the vacuum structure of the scalar potential in a supersymmetric mass varying neutrinos model. The observed dark energy density is identified with false vacuum energy and the dark energy scale of order (10{sup -3} eV){sup 4} is understood by the gravitationally suppressed supersymmetry breaking scale, F(TeV){sup 2}/M{sub Pl}, in the model. The vacuum expectation values of sneutrinos should be tiny in order that the model works. Some decay processes of superparticles into an acceleron and sterile neutrino are also discussed in the model.
Neutrino masses and oscillations in an unconventional model of lepton number violation
NASA Astrophysics Data System (ADS)
Tamvakis, K.; Vergados, J. D.
1985-06-01
Radiatively generated neutrino masses are studied in the framework of a simple model which predicts large mixings for neutrinos independently of the actual value of neutrino masses. The associated phenomenology of neutrino oscillations is analysed in detail. Other lepton violating processes are also discussed.
False Vacuum in the Supersymmetric Mass Varying Neutrino Model
Tanimoto, Morimitsu
2009-04-17
We discuss the vacuum structure of the scalar potential in a supersymmetric Mass Varying Neutrinos model. The observed dark energy density is identified with the false vacuum energy and the dark energy scale of order (10{sup -3} eV){sup 4} is understood by gravitationally suppressed supersymmetry breaking scale, F(TeV{sup 2})/M{sub pl}.
Neutrino masses in the left right supersymmetric model
NASA Astrophysics Data System (ADS)
Frank, M.
2002-08-01
We show that in a left-right supersymmetric model with a Higgs structure that supports the see-saw mechanism, the neutrinos get additional contributions to their masses at one loop level. The mechanism responsible is analogous to the Grossman-Haber see-saw mechanism, but the additional mass terms are proportional to the mass difference of the right-handed sneutrinos. We show that the data on both the solar and the atmospheric neutrinos can be accommodated by either two almost degenerate right-handed sneutrinos, or two heavy sneutrino with different, but still relatively small, mass splittings. We discuss the implications of this result for the masses and mixings of the heavy sneutrinos, and the soft-breaking parameters of the left-right supersymmetric model.
Models of neutrino mass, mixing and CP violation
NASA Astrophysics Data System (ADS)
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.
Predictive model for radiatively induced neutrino masses and mixings with dark matter.
Gustafsson, Michael; No, Jose M; Rivera, Maximiliano A
2013-05-24
A minimal extension of the standard model to naturally generate small neutrino masses and provide a dark matter candidate is proposed. The dark matter particle is part of a new scalar doublet field that plays a crucial role in radiatively generating neutrino masses. The symmetry that stabilizes the dark matter also suppresses neutrino masses to appear first at three-loop level. Without the need of right-handed neutrinos or other very heavy new fields, this offers an attractive explanation of the hierarchy between the electroweak and neutrino mass scales. The model has distinct verifiable predictions for the neutrino masses, flavor mixing angles, colliders, and dark matter signals.
A radiative neutrino mass model with SIMP dark matter
NASA Astrophysics Data System (ADS)
Ho, Shu-Yu; Toma, Takashi; Tsumura, Koji
2017-07-01
We propose the first viable radiative seesaw model, in which the neutrino masses are induced radiatively via the two-loop Feynman diagram involving Strongly Interacting Massive Particles (SIMP). The stability of SIMP dark matter (DM) is ensured by a ℤ 5 discrete symmetry, through which the DM annihilation rate is dominated by the 3 → 2 self-annihilating processes. The right amount of thermal relic abundance can be obtained with perturbative couplings in the resonant SIMP scenario, while the astrophysical bounds inferred from the Bullet cluster and spherical halo shapes can be satisfied. We show that SIMP DM is able to maintain kinetic equilibrium with thermal plasma until the freeze-out temperature via the Yukawa interactions associated with neutrino mass generation.
Neutrino mass model with S3 symmetry and seesaw interplay
NASA Astrophysics Data System (ADS)
Pramanick, Soumita; Raychaudhuri, Amitava
2016-12-01
We develop a seesaw model for neutrino masses and mixing with an S3×Z3 symmetry. It involves an interplay of type-I and type-II seesaw contributions of which the former is subdominant. The S3×Z3 quantum numbers of the fermion and scalar fields are chosen such that the type-II seesaw generates a mass matrix which incorporates the atmospheric mass splitting and sets θ23=π /4 . The solar splitting and θ13 are absent, while the third mixing angle can achieve any value, θ120. Specific choices of θ120 are of interest, e.g., 35.3° (tribimaximal), 45.0° (bimaximal), 31.7° (golden ratio), and 0° (no solar mixing). The role of the type-I seesaw is to nudge all the above into the range indicated by the data. The model results in novel interrelationships between these quantities due to their common origin, making it readily falsifiable. For example, normal (inverted) ordering is associated with θ23 in the first (second) octant. C P violation is controlled by phases in the right-handed neutrino Majorana mass matrix, Mν R . In their absence, only normal ordering is admissible. When Mν R is complex, the Dirac C P phase, δ , can be large, i.e., ˜±π /2 , and inverted ordering is also allowed. The preliminary results from T2K and NOVA which favor normal ordering and δ ˜-π /2 are indicative, in this model, of a lightest neutrino mass of 0.05 eV or more.
Neutrino masses, leptogenesis, and dark matter in a hybrid seesaw model
Gu Peihong; Hirsch, M.; Valle, J. W. F.
2009-02-01
We suggest a hybrid seesaw model where relatively light right-handed neutrinos give no contribution to neutrino mass matrix due to a special symmetry. This allows their Yukawa couplings to the standard model particles to be relatively strong, so that the standard model Higgs boson can decay dominantly to a left- and a right-handed neutrino, leaving another stable right-handed neutrino as cold dark matter. In our model neutrino masses arise via the type-II seesaw mechanism, the Higgs triplet scalars being also responsible for the generation of the matter-antimatter asymmetry via the leptogenesis mechanism.
Is the Zee model the model of neutrino masses?
Smirnov, A.Y.; Tanimoto, M.
1997-02-01
The Zee model predicts naturally two heavy, strongly degenerate and almost maximally mixed neutrinos and one light neutrino with small mixing. This pattern coincides with the one needed for a solution of the atmospheric neutrino problem by {nu}{sub {mu}}{r_arrow}{nu}{sub {tau}} oscillations and for existence of the two component hot dark matter in the Universe. Furthermore, the oscillations {bar {nu}}{sub {mu}}{r_arrow}{bar {nu}}{sub e} can be in the range of sensitivity of KARMEN, LSND experiments. The phenomenology of this scenario is considered and the possibility to check it in the forthcoming experiments is discussed. The scenario implies large values and inverse flavor hierarchy of couplings of the Zee boson with fermions: f{sub e{tau}}{lt}f{sub {mu}{tau}}{le}f{sub e{mu}}{approximately}0.1. The main signatures of the scenario are a strongly suppressed signal of {nu}{sub {mu}}{r_arrow}{nu}{sub {tau}} oscillation in CHORUS and NOMAD experiments, so that a positive result from these experiments will rule out the scenario, the possibility of the observation of {nu}{sub e}{r_arrow}{nu}{sub {tau}} oscillations by CHORUS and NOMAD, the corrections to the muon decay and neutrino-electron scattering at the level of experimental errors, and a branching ratio B({mu}{r_arrow}e{gamma}) bigger than 10{sup {minus}13}. The solar neutrino problem can be solved by the introduction of an additional very light singlet fermion without appreciable modification of the active neutrino pattern. {copyright} {ital 1997} {ital The American Physical Society}
Constraints from unrealistic vacua in the supersymmetric standard model with neutrino mass operators
Kanehata, Yoshimi; Kobayashi, Tatsuo; Konishi, Yasufumi; Shimomura, Takashi
2010-10-01
We analyze a scalar potential of the minimal supersymmetric standard model (MSSM) with neutrino mass operators along unbounded-from-below and color and/or charged breaking directions. We show necessary conditions to avoid the potential minima which can be deeper than the realistic vacuum. These conditions would constrain more strongly than conditions in the MSSM without taking into account neutrino mass operators and can improve the predictive power of supersymmetric models with neutrino mass operators.
Connecting Dirac and Majorana neutrino mass matrices in the minimal left-right symmetric model.
Nemevšek, Miha; Senjanović, Goran; Tello, Vladimir
2013-04-12
Probing the origin of neutrino mass by disentangling the seesaw mechanism is one of the central issues of particle physics. We address it in the minimal left-right symmetric model and show how the knowledge of light and heavy neutrino masses and mixings suffices to determine their Dirac Yukawa couplings. This in turn allows one to make predictions for a number of high and low energy phenomena, such as decays of heavy neutrinos, neutrinoless double beta decay, electric dipole moments of charged leptons, and neutrino transition moments. We also discuss a way of reconstructing the neutrino Dirac Yukawa couplings at colliders such as the LHC.
Cosmological Neutrino Mass Detection: The Best Probe of Neutrino Lifetime
Serpico, Pasquale D.
2007-04-27
Future cosmological data may be sensitive to the effects of a finite sum of neutrino masses even as small as {approx}0.06 eV, the lower limit guaranteed by neutrino oscillation experiments. We show that a cosmological detection of neutrino mass at that level would improve by many orders of magnitude the existing limits on neutrino lifetime, and as a consequence, on neutrino secret interactions with (quasi)massless particles as in Majoron models. On the other hand, neutrino decay may provide a way out to explain a discrepancy < or approx. 0.1 eV between cosmic neutrino bounds and lab data.
Cosmological neutrino mass detection: The Best probe of neutrino lifetime
Serpico, Pasquale D.; /Fermilab
2007-01-01
Future cosmological data may be sensitive to the effects of a finite sum of neutrino masses even as small as {approx}0.06 eV, the lower limit guaranteed by neutrino oscillation experiments. We show that a cosmological detection of neutrino mass at that level would improve by many orders of magnitude the existing limits on neutrino lifetime, and as a consequence on neutrino secret interactions with (quasi-)massless particles as in majoron models. On the other hand, neutrino decay may provide a way-out to explain a discrepancy {approx}< 0.1 eV between cosmic neutrino bounds and Lab data.
Neutrino masses, neutrino oscillations, and cosmological implications
NASA Technical Reports Server (NTRS)
Stecker, F. W.
1982-01-01
Theoretical concepts and motivations for considering neutrinos having finite masses are discussed and the experimental situation on searches for neutrino masses and oscillations is summarized. The solar neutrino problem, reactor, deep mine and accelerator data, tri decay experiments and double beta-decay data are considered and cosmological implications and astrophysical data relating to neutrino masses are reviewed. The neutrino oscillation solution to the solar neutrino problem, the missing mass problem in galaxy halos and galaxy cluster galaxy formation and clustering, and radiative neutrino decay and the cosmic ultraviolet background radiation are examined.
Gauge Trimming of Neutrino Masses
Chen, Mu-Chun; de Gouvea, Andre; Dobrescu, Bogdan A.; /Fermilab
2006-12-01
We show that under a new U(1) gauge symmetry, which is non-anomalous in the presence of one ''right-handed neutrino'' per generation and consistent with the standard model Yukawa couplings, the most general fermion charges are determined in terms of four rational parameters. This generalization of the B-L symmetry with generation-dependent lepton charges leads to neutrino masses induced by operators of high dimensionality. Neutrino masses are thus naturally small without invoking physics at energies above the TeV scale, whether neutrinos are Majorana or Dirac fermions. This ''Leptocratic'' Model predicts the existence of light quasi-sterile neutrinos with consequences for cosmology, and implies that collider experiments may reveal the origin of neutrino masses.
Wolfenstein, L.
1991-12-31
Theoretical prejudices, cosmology, and neutrino oscillation experiments all suggest neutrino mass are far below present direct experimental limits. Four interesting scenarios and their implications are discussed: (1) a 17 keV {nu}{sub {tau}}, (2) a 30 ev {nu}{sub {tau}} making up the dark matter, (3) a 10{sup {minus}3} ev {nu}{sub {mu}} to solve the solar neutrino problem, and (4) a three-neutrino MSW solution.
Mass determination of neutrinos
NASA Technical Reports Server (NTRS)
Chiu, Hong-Yee
1988-01-01
A time-energy correlation method has been developed to determine the signature of a nonzero neutrino mass in a small sample of neutrinos detected from a distant source. The method is applied to the Kamiokande II (Hirata et al., 1987) and IMB (Bionta et al., 1987) observations of neutrino bursts from SN 1987A. Using the Kamiokande II data, the neutrino rest mass is estimated at 2.8 + 2.0, - 1.4 eV and the initial neutrino pulse is found to be less than 0.3 sec full width, followed by an emission tail lasting at least 10 sec.
Mass determination of neutrinos
NASA Technical Reports Server (NTRS)
Chiu, Hong-Yee
1988-01-01
A time-energy correlation method has been developed to determine the signature of a nonzero neutrino mass in a small sample of neutrinos detected from a distant source. The method is applied to the Kamiokande II (Hirata et al., 1987) and IMB (Bionta et al., 1987) observations of neutrino bursts from SN 1987A. Using the Kamiokande II data, the neutrino rest mass is estimated at 2.8 + 2.0, - 1.4 eV and the initial neutrino pulse is found to be less than 0.3 sec full width, followed by an emission tail lasting at least 10 sec.
Neutrino mass, a status report
Robertson, R.G.H.
1993-08-01
Experimental approaches to neutrino mass include kinematic mass measurements, neutrino oscillation searches at rectors and accelerators, solar neutrinos, atmospheric neutrinos, and single and double beta decay. The solar neutrino results yield fairly strong and consistent indications that neutrino oscillations are occurring. Other evidence for new physics is less consistent and convincing.
Dark matter and strong electroweak phase transition in a radiative neutrino mass model
Ahriche, Amine; Nasri, Salah E-mail: snasri@uaeu.ac.ae
2013-07-01
We consider an extension of the standard model (SM) with charged singlet scalars and right handed (RH) neutrinos all at the electroweak scale. In this model, the neutrino masses are generated at three loops, which provide an explanation for their smallness, and the lightest RH neutrino, N{sub 1}, is a dark matter candidate. We find that for three generations of RH neutrinos, the model can be consistent with the neutrino oscillation data, lepton flavor violating processes, N{sub 1} can have a relic density in agreement with the recent Planck data, and the electroweak phase transition can be strongly first order. We also show that the charged scalars may enhance the branching ratio h→γγ, where as h→γZ get can get few percent suppression. We also discuss the phenomenological implications of the RH neutrinos at the collider.
Neutrino masses and family replication
Hung, P.Q.
1999-06-01
The issue of whether or not there is any link between the smallness of the neutrino mass (if present) and the odd or even nature of the number of families is investigated. It is found that, by assuming the existence of right-handed neutrinos (which would imply that neutrinos will have a mass) and a new chiral SU(2) gauge theory, a constraint on the nature of the number of families can be obtained. In addition, a model, based on that extra SU(2), is constructed where it is plausible to have one {open_quotes}very heavy{close_quotes} fourth neutrino and three almost degenerate light neutrinos whose masses are all of the Dirac type. {copyright} {ital 1999} {ital The American Physical Society}
New U(1) gauge model of radiative lepton masses with sterile neutrino and dark matter
Adhikari, Rathin; Borah, Debasish; Ma, Ernest
2016-02-23
Here, an anomaly-free U(1) gauge extension of the standard model (SM) is presented. Only one Higgs doublet with a nonzero vacuum expectation is required as in the SM. New fermions and scalars as well as all SM particles transform nontrivially under this U(1), resulting in a model of three active neutrinos and one sterile neutrino, all acquiring radiative masses. Charged-lepton masses are also radiative as well as the mixing between active and sterile neutrinos. At the same time, a residual Z2 symmetry of the U(1) gauge symmetry remains exact, allowing for the existence of dark matter.
Direct neutrino mass measurements
NASA Astrophysics Data System (ADS)
Drexlin, G.
2008-11-01
Direct neutrino mass measurements are based on high precision spectroscopy studies close to the kinematic end-point of low-energy β-emitters such as 3H and 187Re. Relying only on energy-momentum conservation in β-decay, they offer the only model-independent method to measure the absolute ν-mass scale with sub-eV sensitivity. The two most sensitive detection principles, electrostatic retarding spectrometers and microbolometers, are complementary to each other, and two experiments are currently being prepared to explore ν-masses down to m(ν) = 200 meV. β-spectroscopy will thus allow to constrain the role of neutrino hot dark matter in structure formation, as well as to explore the parameter region of ν-mass scenarios with quasi-degenerate pattern. The MARE project will investigate the β-decay of 187Re with bolometers based on metallic Re and AgReO4 in a two-staged approach: in a phase-I set-up a sensitivity of m(ν) = 2 eV is expected, forming the basis for a later sub-eV phase-II. The Karlsruhe Tritium Neutrino (KATRIN) experiment is currently being set-up on the site of Tritium Laboratory at KIT. The experiment will combine an ultra-luminous windowless gaseous tritium source with a high resolution electrostatic spectrometer and offer an unprecedented precision in β-decay studies, pushing this technique to its technological limits. First KATRIN measurements with 3H after successful system integration are expected for mid-2011. This contribution gives a status report and outlook for both experiments and discusses the impact of direct ν-mass experiments on astroparticle physics.
Baryon asymmetry via leptogenesis in a neutrino mass model with complex scaling
NASA Astrophysics Data System (ADS)
Samanta, Rome; Chakraborty, Mainak; Roy, Probir; Ghosal, Ambar
2017-03-01
Baryogenesis via leptogenesis is investigated in a specific model of light neutrino masses and mixing angles. The latter was proposed on the basis of an assumed complex-extended scaling property of the neutrino Majorana mass matrix Mν, derived with a type-1 seesaw from a Dirac mass matrix mD and a heavy singlet neutrino Majorana mass matrix MR. One of its important features, highlighted here, is that there is a common source of the origin of a nonzero θ13 and the CP violating lepton asymmetry through the imaginary part of mD. The model predicted CP violation to be maximal for the Dirac type and vanishing for the Majorana type. We assume strongly hierarchical mass eigenvalues for MR. The leptonic CP asymmetry parameter εα1 mm with lepton flavor α, originating from the decays of the lightest of the heavy neutrinos N1 (of mass M1) at a temperature T ~ M1, is what matters here with the lepton asymmetries, originating from the decays of N2,3, being washed out. The light leptonic and heavy neutrino number densities (normalized to the entropy density) are evolved via Boltzmann equations down to electroweak temperatures to yield a baryon asymmetry through sphaleronic transitions. The effects of flavored vs. unflavored leptogenesis in the three mass regimes (1) M1 < 109 GeV, (2) 109 GeV < M1 < 1012 GeV and (3) M1 > 1012 GeV are numerically worked out for both a normal and an inverted mass ordering of the light neutrinos. Corresponding results on the baryon asymmetry of the universe are obtained, displayed and discussed. For values close to the best-fit points of the input neutrino mass and mixing parameters, obtained from neutrino oscillation experiments, successful baryogenesis is achieved for the mass regime (2) and a normal mass ordering of the light neutrinos with a nonzero θ13 playing a crucial role. However, the other possibility of an inverted mass ordering for the same mass regime, though disfavored, cannot be excluded. A discussion is also given on the
Systematic U(1 ) B - L extensions of loop-induced neutrino mass models with dark matter
NASA Astrophysics Data System (ADS)
Ho, Shu-Yu; Toma, Takashi; Tsumura, Koji
2016-08-01
We study the gauged U(1 ) B - L extensions of the models for neutrino masses and dark matter. In this class of models, tiny neutrino masses are radiatively induced through the loop diagrams, while the origin of the dark matter stability is guaranteed by the remnant of the gauge symmetry. Depending on how the lepton number conservation is violated, these models are systematically classified. We present complete lists for the one-loop Z2 and the two-loop Z3 radiative seesaw models as examples of the classification. The anomaly cancellation conditions in these models are also discussed.
Tritium beta decay, neutrino mass matrices, and interactions beyond the standard model
NASA Astrophysics Data System (ADS)
Stephenson, G. J., Jr.; Goldman, T.; McKellar, B. H. J.
2000-11-01
The interference of charge changing interactions, weaker than the V-A standard model (SM) interaction and having a different Lorentz structure, with that SM interaction, can, in principle, produce effects near the end point of the tritium beta decay spectrum which are of a different character from those produced by the purely kinematic effect of neutrino mass expected in the simplest extension of the SM. We show that the existence of more than one mass eigenstate can lead to interference effects at the end point that are stronger than those occurring over the entire spectrum. We discuss these effects both for the special case of Dirac neutrinos and the more general case of Majorana neutrinos and show that, for the present precision of the experiments, one formula should suffice to express the interference effects in all cases. Implications for ``sterile'' neutrinos are noted.
Neutrino mass from triton decay
NASA Astrophysics Data System (ADS)
Weinheimer, Christian
2006-07-01
Since the discovery of neutrino flavor oscillation in different fields and by many different experiments we believe that neutrinos have non-vanishing masses in contrast to their current description within the Standard Model of particle physics. However, the absolute values of the neutrino masses, which are as important for particle physics as they are for cosmology and astrophysics, cannot be determined by oscillation experiments alone. There are a few ways to determine the neutrino mass scale, but the only model-independent method is the investigation of the electron energy spectrum of a β decay near its endpoint with tritium being the ideal isotope for the classical spectrometer set-up. The tritium β decay experiments at Mainz and Troitsk have recently been finished. At Mainz all relevant systematic uncertainties have been investigated by dedicated experiments yielding an upper limit of m(ν)<2.3eV/c (90% C.L.). The new Karlsruhe Tritium Neutrino Experiment (KATRIN) will enhance the sensitivity on the neutrino mass by an ultra-precise measurement of the tritium β decay spectrum near the endpoint by another order of magnitude down to 0.2 eV/c2 by using a very strong windowless gaseous molecular tritium source and a huge ultra-high resolution electrostatic spectrometer of MAC-E-Filter type. The recent achievements in test experiments show, that this very challenging experiment is feasible.
Direct measurements of neutrino mass
Robertson, R.G.H.
1991-01-01
Some recent developments in the experimental search for neutrino mass are discussed. New data from Los Alamos on the electron neutrino mass as measured in tritium beta decay give an upper limit of 9.3 eV at the 95% confidence level. This result is not consistent with the long-standing ITEP result of 26(5) eV within a model-independent'' range of 17 to 40 eV. It now appears that the electron neutrino is not sufficiently massive to close the universe by itself. Hime and Jelley report finding new evidence for a 17-keV neutrino in the {Beta} decay of {sup 35}S and {sup 63}Ni. Many other experiments are being reported and the situation is still unresolved. 56 refs., 1 fig., 3 tabs.
Maximum Entropy Inferences on the Axion Mass in Models with Axion-Neutrino Interaction
NASA Astrophysics Data System (ADS)
Alves, Alexandre; Dias, Alex Gomes; da Silva, Roberto
2017-08-01
In this work, we use the maximum entropy principle (MEP) to infer the mass of an axion which interacts to photons and neutrinos in an effective low energy theory. The Shannon entropy function to be maximized is defined in terms of the axion branching ratios. We show that MEP strongly constrains the axion mass taking into account the current experimental bounds on the neutrinos masses. Assuming that the axion is massive enough to decay into all the three neutrinos and that MEP fixes all the free parameters of the model, the inferred axion mass is in the interval 0.1 eV < m A < 0.2 eV, which can be tested by forthcoming experiments such as IAXO. However, even in the case where MEP fixes just the axion mass and no other parameter, we found that 0.1 eV < m A < 6.3 eV in the DFSZ model with right-handed neutrinos. Moreover, a light axion, allowed to decay to photons and the lightest neutrino only, is determined by MEP as a viable dark matter candidate.
AN OVERVIEW OF NEUTRINO MASSES AND MIXING IN SO(10) MODELS.
CHEN,M.C.MAHANTHAPPA,K.T.
2003-06-05
We review in this talk various SUSY SO(10) models. Specifically, we discuss how small neutrino masses are generated in and generic predictions of different SO(10) models. A comparison of the predictions of these models for sin{sup 2} {theta}{sub 13}is given.
Pierce, Aaron; Murayama, Hitoshi
2003-10-28
Recent data from the Wilkinson Microwave Anisotropy Probe (WMAP) place important bounds on the neutrino sector. The precise determination of the baryon number in the universe puts a strong constraint on the number of relativistic species during Big-Bang Nucleosynthesis. WMAP data, when combined with the 2dF Galaxy Redshift Survey (2dFGRS), also directly constrain the absolute mass scale of neutrinos. These results impinge upon a neutrino oscillation interpretation of the result from the Liquid Scintillator Neutrino Detector (LSND).We also note that the Heidelberg-Moscow evidence for neutrinoless double beta decay is only consistent with the WMAP+2dFGRS data for the largest values of the nuclear matrix element.
Neutrino masses and solar neutrinos
Wolfenstein, L.
1992-11-01
It has been pointed out by Bahcall and Bethe and others that all solar neutrino data can be explained by MSW oscillations with m({nu}{sub {mu}}) {approximately} 10{sup {minus}3} eV consistent with ideas grand unified theories (GUTS). There is a second possibility consistent with GUTS ideas with m({nu}{sub {tau}}) {approximately} 10{sup {minus}2} eV and m({nu} {sub {mu}}) {approximately} 10 {sup {minus}4} eV. The two cases can be distinguished by a measurement of the solar neutrinos from {sup {tau}}Be.
A realistic model of neutrino masses with a large neutrinoless double beta decay rate
NASA Astrophysics Data System (ADS)
del Aguila, Francisco; Aparici, Alberto; Bhattacharya, Subhaditya; Santamaria, Arcadi; Wudka, Jose
2012-05-01
The minimal Standard Model extension with the Weinberg operator does accommodate the observed neutrino masses and mixing, but predicts a neutrinoless double beta (0 νββ) decay rate proportional to the effective electron neutrino mass, which can be then arbitrarily small within present experimental limits. However, in general 0 νββ decay can have an independent origin and be near its present experimental bound; whereas neutrino masses are generated radiatively, contributing negligibly to 0 νββ decay. We provide a realization of this scenario in a simple, well defined and testable model, with potential LHC effects and calculable neutrino masses, whose two-loop expression we derive exactly. We also discuss the connection of this model to others that have appeared in the literature, and remark on the significant differences that result from various choices of quantum number assignments and symmetry assumptions. In this type of models lepton flavor violating rates are also preferred to be relatively large, at the reach of foreseen experiments. Interestingly enough, in our model this stands for a large third mixing angle, {{si}}{{{n}}^{{2}}}{θ_{{{13}}}}{˜}}}{ > }}0.00{8} , when μ→ eee is required to lie below its present experimental limit.
Direct neutrino mass measurements
NASA Astrophysics Data System (ADS)
Weinheimer, Christian
2013-03-01
Direct neutrino mass experiments are complementary to searches for neutrinoless double β-decay and to analyses of cosmological data. The previous tritium beta decay experiments at Mainz and at Troitsk have achieved upper limits on the neutrino mass of about 2 eV/c2 . The KATRIN experiment under construction will improve the neutrino mass sensitivity down to 200 meV/c2 by increasing strongly the statistics and—at the same time—reducing the systematic uncertainties. Huge improvements have been made to operate the system extremely stably and at very low background rate. The latter comprises new methods to reject secondary electrons from the walls as well as to avoid and to eject electrons stored in traps. As an alternative to tritium β-decay experiments cryo-bolometers investigating the endpoint region of 187Re β-decay or the electron capture of 163Ho are being developed. This article briefly reviews the current status of the direct neutrino mass measurements.
S3 × Bbb Z2 model for neutrino mass matrices
NASA Astrophysics Data System (ADS)
Grimus, Walter; Lavoura, Luís
2005-08-01
We propose a model for lepton mass matrices based on the seesaw mechanism, a complex scalar gauge singlet and a horizontal symmetry S3 × Bbb Z2. In a suitable weak basis, the charged-lepton mass matrix and the neutrino Dirac mass matrix are diagonal, but the vacuum expectation value of the scalar gauge singlet renders the Majorana mass matrix of the right-handed neutrinos non-diagonal, thereby generating lepton mixing. When the symmetry S3 is not broken in the scalar potential, the effective light-neutrino Majorana mass matrix enjoys μ-τ interchange symmetry, thus predicting maximal atmospheric neutrino mixing together with Ue3 = 0. A partial and less predictive form of μ-τ interchange symmetry is obtained when the symmetry S3 is softly broken in the scalar potential. Enlarging the symmetry group S3 × Bbb Z2 by an additional discrete electron-number symmetry Bbb Z2(e), a more predicitive model is obtained, which is in practice indistinguishable from a previous one based on the group D4.
Neutrinos beyond the Standard Model
Valle, J.W.F.
1989-08-01
I review some basic aspects of neutrino physics beyond the Standard Model such as neutrino mixing and neutrino non-orthogonality, universality and CP violation in the lepton sector, total lepton number and lepton flavor violation, etc.. These may lead to neutrino decays and oscillations, exotic weak decay processes, neutrinoless double /beta/ decay, etc.. Particle physics models are discussed where some of these processes can be sizable even in the absence of measurable neutrino masses. These may also substantially affect the propagation properties of solar and astrophysical neutrinos. 39 refs., 4 figs.
NASA Astrophysics Data System (ADS)
Borgohain, Happy; Das, Mrinal Kumar
2017-09-01
We have studied neutrinoless double beta decay and charged lepton flavour violation in broken μ - τ symmetric neutrino masses in a generic left-right symmetric model (LRSM). The leading order μ - τ symmetric mass matrix originates from the type I (II) seesaw mechanism, whereas the perturbations to μ - τ symmetry in order for generation of non-zero reactor mixing angle 𝜃 13, as required by latest neutrino oscillation data, originates from the type II (I) seesaw mechanism. In our work, we considered four different realizations of μ - τ symmetry, viz. Tribimaximal Mixing (TBM), Bimaximal Mixing (BM), Hexagonal Mixing (HM) and Golden Ratio Mixing (GRM). We then studied the new physics contributions to neutrinoless double beta decay (NDBD) ignoring the left-right gauge boson mixing and the heavy-light neutrino mixing within the framework of LRSM. We have considered the mass of the gauge bosons and scalars to be around TeV and studied the effects of the new physics contributions on the effective mass and the NDBD half life and compared with the current experimental limit imposed by KamLAND-Zen. We further extended our analysis by correlating the lepton flavour violation of the decay processes, ( μ → 3 e) and ( μ → e γ) with the lightest neutrino mass and atmospheric mixing angle 𝜃 23 respectively.
NASA Astrophysics Data System (ADS)
Borgohain, Happy; Das, Mrinal Kumar
2017-06-01
We have studied neutrinoless double beta decay and charged lepton flavour violation in broken μ - τ symmetric neutrino masses in a generic left-right symmetric model (LRSM). The leading order μ - τ symmetric mass matrix originates from the type I (II) seesaw mechanism, whereas the perturbations to μ - τ symmetry in order for generation of non-zero reactor mixing angle 𝜃 13, as required by latest neutrino oscillation data, originates from the type II (I) seesaw mechanism. In our work, we considered four different realizations of μ - τ symmetry, viz. Tribimaximal Mixing (TBM), Bimaximal Mixing (BM), Hexagonal Mixing (HM) and Golden Ratio Mixing (GRM). We then studied the new physics contributions to neutrinoless double beta decay (NDBD) ignoring the left-right gauge boson mixing and the heavy-light neutrino mixing within the framework of LRSM. We have considered the mass of the gauge bosons and scalars to be around TeV and studied the effects of the new physics contributions on the effective mass and the NDBD half life and compared with the current experimental limit imposed by KamLAND-Zen. We further extended our analysis by correlating the lepton flavour violation of the decay processes, (μ → 3e) and (μ → e γ) with the lightest neutrino mass and atmospheric mixing angle 𝜃 23 respectively.
Model for neutrino masses and dark matter with a discrete gauge symmetry
NASA Astrophysics Data System (ADS)
Chang, We-Fu; Wong, Chi-Fong
2012-01-01
A simple renormalizable U(1) gauge model is constructed to explain the smallness of the active neutrino masses and provide the stable cold dark matter candidate simultaneously. The local U(1) symmetry is assumed to be spontaneously broken by a scalar field around the TeV scale. The active neutrino masses are then generated at one-loop level. This model contains several cold dark matter candidates whose stability is guaranteed by a residual discrete gauge Z2 symmetry à la the Krauss-Wilczek mechanism. Unlike the other dark matter models, no further global discrete or continuous symmetry is introduced. Moreover, the masses of all fermionic degrees of freedom beyond the standard model are closely related to the scale of spontaneous breaking of U(1); thus they could be probed at or below the TeV scale. The possible cosmological and phenomenological consequences are briefly discussed.
Constraints on texture zero and cofactor zero models for neutrino mass
Whisnant, K.; Liao, Jiajun; Marfatia, D.
2014-06-24
Imposing a texture or cofactor zero on the neutrino mass matrix reduces the number of independent parameters from nine to seven. Since five parameters have been measured, only two independent parameters would remain in such models. We find the allowed regions for single texture zero and single cofactor zero models. We also find strong similarities between single texture zero models with one mass hierarchy and single cofactor zero models with the opposite mass hierarchy. We show that this correspondence can be generalized to texture-zero and cofactor-zero models with the same homogeneous costraints on the elements and cofactors.
Neutrino Oscillations and Neutrino Masses
NASA Astrophysics Data System (ADS)
Fritzsch, Harald
In 1914 James Chadwick discovered that energy and momentum were not conserved in the beta decay of atomic nuclei. For the next 16 years this phenomenon was not understood. In 1930 Wolfgang Pauli suggested in a letter to the participants of a conference in Tuebingen, that in the beta decays not only an electron was emitted, but also a neutral particle, which could not be observed. The energy and momentum of this particle would be the observed missing energy and momentum. Enrico Fermi proposed a name for this hypothetical particle: neutrino...
Starobinsky-like inflation and neutrino masses in a no-scale SO(10) model
NASA Astrophysics Data System (ADS)
Ellis, John; Garcia, Marcos A. G.; Nagata, Natsumi; Nanopoulos, Dimitri V.; Olive, Keith A.
2016-11-01
Using a no-scale supergravity framework, we construct an SO(10) model that makes predictions for cosmic microwave background observables similar to those of the Starobinsky model of inflation, and incorporates a double-seesaw model for neutrino masses consistent with oscillation experiments and late-time cosmology. We pay particular attention to the behaviour of the scalar fields during inflation and the subsequent reheating.
Starobinsky-like inflation and neutrino masses in a no-scale SO(10) model
Ellis, John; Garcia, Marcos A.G.; Nagata, Natsumi; Nanopoulos, Dimitri V.; Olive, Keith A.
2016-11-08
Using a no-scale supergravity framework, we construct an SO(10) model that makes predictions for cosmic microwave background observables similar to those of the Starobinsky model of inflation, and incorporates a double-seesaw model for neutrino masses consistent with oscillation experiments and late-time cosmology. We pay particular attention to the behaviour of the scalar fields during inflation and the subsequent reheating.
Study of radiative neutrino mass generation and physics beyond the Standard Model
NASA Astrophysics Data System (ADS)
Julio, Julio
Scope and methods. In this dissertation I propose a new class of models of radiative neutrino mass generation induced by leptoquarks. These models generate neutrino mass at two-loop level. Chapter 2 and Chapter 3 are devoted to discuss such models. In Chapter 4, I study the perturbative unitarity constraints on class of W' models attempting to explain the Tevatron top quark asymmetry and CDF Wjj anomaly. Findings and conclusions. In one model discussed in Chapter 2, it is shown that all of neutrino oscillation data can be explained consistently. The lightest of neutrinos is predicted to be massless with the hierarchy of neutrino mass being normal. The oscillation parameters are linked to leptoquark branching ratios. Neutrinoless double beta decay might be observed through vector-scalar exchange. New contribution to CP violation in B0s system arises from leptoquark box diagrams, which can explain the apparent anomaly observed in experiments. In Chapter 3, I propose a model of two-loop neutrino mass involving a charge 2/3 vectorlike particle and a doublet of leptoquark scalar. This model predicts one of the neutrinos to be massless and admits both the normal and inverted neutrino mass hierarchies with correlated predictions for ℓi → ℓ j + gamma branching ratios. New contributions to CP violation in B0s-B0s mixing arise in the model through leptoquark box diagrams and through mixing of quarks with vectorlike quark. These can explain the anomalous dimuon events reported by the D0 Collaboration. These leptoquarks, with masses below 500 GeV, also provide a natural resolution to the apparent discrepancy in the measured values of the CP violation parameters sin 2beta and epsilonK. In Chapter 4, I study perturbative unitarity constraints on general W' models by considering the high energy behavior of fermion scattering into gauge bosons. In most cases that are surveyed, a Z' boson with a comparable mass must be present for the theory to be consistent, with fixed
Radiative neutrino mass, dark matter, and leptogenesis
Gu Peihong; Sarkar, Utpal
2008-05-15
We propose an extension of the standard model, in which neutrinos are Dirac particles and their tiny masses originate from a one-loop radiative diagram. The new fields required by the neutrino mass generation also accommodate the explanation for the matter-antimatter asymmetry and dark matter in the Universe.
Measuring the neutrino mass using intense photon and neutrino beams
NASA Astrophysics Data System (ADS)
Dicus, Duane A.; Repko, Wayne W.; Vega, Roberto
2000-11-01
We compute the cross section for neutrino-photon scattering taking into account a neutrino mass. We explore the possibility of using intense neutrino beams, such as those available at proposed muon colliders, together with high powered lasers to probe the neutrino mass in photon-neutrino collisions.
A critical analysis of one-loop neutrino mass models with minimal dark matter
NASA Astrophysics Data System (ADS)
Ahriche, Amine; McDonald, Kristian L.; Nasri, Salah; Picek, Ivica
2016-06-01
A recent paper investigated minimal RνMDM models with the type T1-iii and T3 one-loop topologies. However, the candidate most-minimal model does not possess an accidental symmetry - the scalar potential contains an explicit symmetry breaking term, rendering the dark matter unstable. We present two models that cure this problem. However, we further show that all of the proposed minimal one-loop RνMDM models suffer from a second problem - an additional source of explicit Z2 symmetry breaking in the Yukawa sector. We perform a more-general analysis to show that neutrino mass models using either the type T3 or type T1-iii one-loop topologies do not give viable minimal dark matter candidates. Consequently, one-loop models of neutrino mass with minimal dark matter do not appear possible. Thus, presently there remains a single known (three-loop) model of neutrino mass that gives stable dark matter without invoking any new symmetries.
Predictivity of neutrino mass sum rules
NASA Astrophysics Data System (ADS)
Gehrlein, Julia; Merle, Alexander; Spinrath, Martin
2016-11-01
Correlations between light neutrino observables are arguably the strongest predictions of lepton flavor models based on (discrete) symmetries, except for the very few cases which unambiguously predict the full set of leptonic mixing angles. A subclass of these correlations is neutrino mass sum rules, which connect the three (complex) light neutrino mass eigenvalues among each other. This connection constrains both the light neutrino mass scale and the Majorana phases, so that mass sum rules generically lead to a nonzero value of the lightest neutrino mass and to distinct predictions for the effective mass probed in neutrinoless double beta decay. However, in nearly all cases known, the neutrino mass sum rules are not exact and receive corrections from various sources. We introduce a formalism to handle these corrections perturbatively in a model-independent manner, which overcomes issues present in earlier approaches. Our ansatz allows us to quantify the modification of the predictions derived from neutrino mass sum rules. We show that, in most cases, the predictions are fairly stable: while small quantitative changes can appear, they are generally rather mild. We therefore establish the predictivity of neutrino mass sum rules on a level far more general than previously known.
Neutrino mass and mixing: Summary of the neutrino sessions
Bowles, T.J.
1993-01-01
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.
Validity of quasi-degenerate neutrino mass models and their predictions on baryogenesis
NASA Astrophysics Data System (ADS)
Francis, Ng. K.; Nimai Singh, N.
2012-10-01
Quasi-degenerate neutrino mass models (QDN) which can explain the current data on neutrino masses and mixings, are studied. In the first part, we study the effect of CP-phases on QDN mass matrix (mLL) obeying μ-τ symmetry in normal hierarchical (QD-NH) and inverted hierarchical (QD-IH) patterns. The numerical predictions are consistent with observed data on (i) solar mixing angle (θ12) which lies below tri-bimaximal (TBM) value, (ii) absolute neutrino masses consistent with 0νββ decay mass parameter (mee) and (iii) cosmological upper bound ∑i3mi. mLL is parameterized using only two unknown parameters (ɛ,η) within μ-τ symmetry. The second part deals with the estimation of observed baryon asymmetry of the universe (BAU) where we consider the Majorana CP violating phases (α,β) and the Dirac neutrino mass matrix (mLR). mLR is taken as either the charged lepton or the up quark mass matrix. α, β is derived from the heavy right-handed Majorana mass matrix MRR. MRR is generated from mLL and mLR through inversion of Type-I seesaw formula. The predictions for BAU are nearly consistent with observations for flavoured thermal leptogenesis scenario for Type-IA in both QD-NH and QD-IH models. We also observe some enhancement effects in flavour leptogenesis compared to non-flavour leptogenesis by a magnitude of order one. In non-thermal leptogenesis QD-NH Type-IA is the only model consistent with observed data on baryon asymmetry. QD-NH model appears to be more favourable than those of QD-IH. The predicted inflaton mass needed to produce the BAU is found to be Mϕ˜1010 GeV corresponding to the reheating temperature TR=106 GeV. The present analysis shows that the three absolute neutrino masses may exhibit quasi-degenerate pattern in nature.
A class of three-loop models with neutrino mass and dark matter
NASA Astrophysics Data System (ADS)
Chen, Chian-Shu; McDonald, Kristian L.; Nasri, Salah
2014-06-01
We study a class of three-loop models for neutrino mass in which dark matter plays a key role in enabling the mass diagram. The simplest models in this class have Majorana dark matter and include the proposal of Krauss, Nasri and Trodden; we identify the remaining related models, including the viable colored variants. The next-to-simplest models use either more multiplets and/or a slight modification of the loop-diagram, and predict inert N-tuplet scalar dark matter.
Model independent extraction of the axial mass parameter in CCQE anti neutrino-nucleon scattering
NASA Astrophysics Data System (ADS)
Grebe, Heather
2013-10-01
Neutrino oscillation studies depend on a consistent value for the axial mass. For this reason, a model-independent extraction of this parameter from quasielastic (anti)neutrino-nucleon scattering data is vital. While most studies employ a model-dependent extraction using the dipole model of the axial form factor, we present a model-independent description using the z expansion of the axial form factor. Quasielastic antineutrino scattering data on C-12 from the MiniBooNE experiment are analyzed using this model-independent description. The value found, mA = 0 .85-0 . 06 + 0 . 13 +/- 0 . 13 GeV, differs significantly from the value utilized by the MiniBooNE Collaboration, mA = 1 . 35 GeV. Advisor: Dr. Gil Paz Wayne State Univerity.
Decaying warm dark matter and neutrino masses.
Lattanzi, M; Valle, J W F
2007-09-21
Neutrino masses may arise from spontaneous breaking of ungauged lepton number. Because of quantum gravity effects the associated Goldstone boson - the majoron - will pick up a mass. We determine the lifetime and mass required by cosmic microwave background observations so that the massive majoron provides the observed dark matter of the Universe. The majoron decaying dark matter scenario fits nicely in models where neutrino masses arise via the seesaw mechanism, and may lead to other possible cosmological implications.
Decaying Warm Dark Matter and Neutrino Masses
Lattanzi, M.; Valle, J. W. F.
2007-09-21
Neutrino masses may arise from spontaneous breaking of ungauged lepton number. Because of quantum gravity effects the associated Goldstone boson--the majoron--will pick up a mass. We determine the lifetime and mass required by cosmic microwave background observations so that the massive majoron provides the observed dark matter of the Universe. The majoron decaying dark matter scenario fits nicely in models where neutrino masses arise via the seesaw mechanism, and may lead to other possible cosmological implications.
Evidence for neutrino mass: A decade of discovery
Heeger, Karsten M.
2004-12-08
Neutrino mass and mixing are amongst the major discoveries of recent years. From the observation of flavor change in solar and atmospheric neutrino experiments to the measurements of neutrino mixing with terrestrial neutrinos, recent experiments have provided consistent and compelling evidence for the mixing of massive neutrinos. The discoveries at Super-Kamiokande, SNO, and KamLAND have solved the long-standing solar neutrino problem and demand that we make the first significant revision of the Standard Model in decades. Searches for neutrinoless double-beta decay probe the particle nature of neutrinos and continue to place limits on the effective mass of the neutrino. Possible signs of neutrinoless double-beta decay will stimulate neutrino mass searches in the next decade and beyond. I review the recent discoveries in neutrino physics and the current evidence for massive neutrinos.
NASA Astrophysics Data System (ADS)
Xing, Zhi-Zhong; Zhang, He; Zhou, Shun
Assuming the Majorana nature of massive neutrinos, we generalize the Friedberg-Lee neutrino mass model to include CP violation in the neutrino mass matrix Mν. The most general case with all the free parameters of Mν being complex is discussed. We show that a favorable neutrino mixing pattern (with θ12 ≈ 35.3°, θ23 = 45°, θ13 ≠ 0° and δ = 90°) can naturally be derived from Mν, if it has an approximate or softly-broken μ-τ symmetry. We also point out a different way to obtain the nearly tri-bimaximal neutrino mixing pattern with δ = 0° and non-vanishing Majorana phases.
Seesaw model in SO(10) with an upper limit on right-handed neutrino masses
NASA Astrophysics Data System (ADS)
Abud, M.; Buccella, F.; Falcone, D.; Oliver, L.
2012-08-01
In the framework of SO(10) gauge unification and the seesaw mechanism, we show that the upper bound on the mass of the heaviest right-handed neutrino MR3<3×1011GeV, given by the Pati-Salam intermediate scale of B-L spontaneous symmetry breaking, constrains the observables related to the left-handed light neutrino mass matrix. We assume such an upper limit on the masses of right-handed neutrinos and, as a first approximation, a Cabibbo form for the matrix VL that diagonalizes the Dirac neutrino matrix mD. Using the inverse seesaw formula, we show that our hypotheses imply a triangular relation in the complex plane of the light neutrino masses with the Majorana phases. We obtain normal hierarchy with an absolute scale for the light neutrino spectrum. Two regions are allowed for the lightest neutrino mass m1 and for the Majorana phases, implying predictions for the neutrino mass measured in Tritium decay and for the double beta decay effective mass |⟨mee⟩|.
Ishikawa, K.; Tobita, Y.
2008-05-21
We report (1) the current status of neutrino parameters and (2) our recent work on implications of particle's coherence, which are weakly related each others. In the first part, current status of the neutrino parameters obtained from oscillation experiments and their prospects are briefly reviewed. From various oscillation experiments, existence of three mass scales have been confirmed. One value of the difference of mass squared is around 10{sup -3}eV{sup 2} and another is around 10{sup -5}eV{sup 2}. Although mixing angles are partly found, one important angle, {theta}{sub 13} is left unknown.In the second part, implications of coherence length of particles in the scattering of ultra-high energy cosmic rays (UHCR) with cosmic background radiations (CBR) is discussed. Although coherence length is regarded usually irrelevant to observations, its role is important in several situations of recent experiments which include that of the ultra-high energy charged particles. Here we discuss the scattering of UHCR with CBR.
Neff versus the lightest neutrino mass
NASA Astrophysics Data System (ADS)
Kekic, Marija
2016-04-01
Within the framework of low-scale Type I seesaw models with two and three extra sterile neutrinos we evaluate the production of the sterile states in the Early Universe. We explore the full parameter space and find that in the model with two extra states both of them reach thermal equilibrium with the primordial plasma. In the model with three sterile neutrinos, if the lightest active neutrino mass is below O (10-3eV) one sterile neutrino might not thermalize, while the other two always reach thermalization. Applying constrains from both extra radiation at BBN and CMB, and the dark matter allowed abundance, we show that the spectra of heavier states are severely restricted in the mass range 1eV-100MeV. The possible impact of extra sterile neutrinos on neutrinoless double beta decay is also discussed.
Constraints on Neutrino Mass from Galaxy Surveys
NASA Astrophysics Data System (ADS)
Cuesta, A. J.; Niro, V.; Verde, L.
2017-03-01
Modern large-scale galaxy surveys, combined with measurements of the cosmic microwave background, have managed to constrain the sum of neutrino masses to an order of magnitude below the limit placed by laboratory experiments. We discuss the signature of massive neutrinos in the distribution of galaxies and the current state of the art of neutrino mass constraints, focusing on parameter degeneracies that reveal how we can improve current constraints with next-generation galaxy surveys. We also comment on how the near future cosmology experiments are an opportunity for the first measurement of the value of the sum of neutrino masses, or alternatively, to find profound implications for neutrino physics extensions beyond the Standard Model.
Revised WMAP constraints on neutrino masses and other extensions of the minimal {lambda}CDM model
Kristiansen, Jostein R.; Elgaroey, Oystein; Eriksen, Hans Kristian
2006-12-15
Recently, two issues concerning the three-year Wilkinson Microwave Anisotropy Probe (WMAP) likelihood code were pointed out. On large angular scales (l(less-or-similar sign)30), a suboptimal likelihood approximation resulted in a small power excess. On small angular scales (l(greater-or-similar sign)300), over-subtraction of unresolved point sources produced a small power deficit. For a minimal six-parameter cosmological model, these two effects conspired to decrease the value of n{sub s} by {approx}0.7{sigma}. In this paper, we study the change in preferred parameter ranges for extended cosmological models, including running of n{sub s}, massive neutrinos, curvature, and the equation of state for dark energy. We also include large-scale structure and supernova data in our analysis. We find that the parameter ranges for {alpha}{sub s}, {omega}{sub k} and w are not much altered by the modified analysis. For massive neutrinos the upper limit on the sum of the neutrino masses decreases from M{sub {nu}}<1.90 eV to M{sub {nu}}<1.57 eV when using the modified WMAP code and WMAP data only. We also find that the shift of n{sub s} to higher values is quite robust to these extensions of the minimal cosmological model.
Pathways to naturally small Dirac neutrino masses
NASA Astrophysics Data System (ADS)
Ma, Ernest; Popov, Oleg
2017-01-01
If neutrinos are truly Dirac fermions, the smallness of their masses may still be natural if certain symmetries exist beyond those of the standard model of quarks and leptons. We perform a systematic study of how this may occur at tree level and in one loop. We also propose a scotogenic version of the left-right gauge model with naturally small Dirac neutrino masses in one loop.
Limits on neutrino masses from neutrinoless double-β decay.
Barea, J; Kotila, J; Iachello, F
2012-07-27
Neutrinoless double-β decay is of fundamental importance for the determining neutrino mass. By combining a calculation of nuclear matrix elements within the framework of the microscopic interacting boson model with an improved calculation of phase space factors, we set limits on the average light neutrino mass and on the average inverse heavy neutrino mass (flavor-violating parameter).
Marshak, R. E.
1982-01-01
Several crucial tests of three popular unification models (of strong, electromagnetic, and weak interactions) are described. The models are SU(5) and SO(10) at the grand unification theory (GUT) level and SU(4)C × SU(2)L × SU(2)R at the partial unification theory (PUT) level. The tests selected for discussion are the finiteness of the neutrino mass in the electron volt region, the decay of protons into antileptons in the range of 1031± yr, and the detectability of neutron oscillations at all. The PUT group can also be tested by establishing the existence of four generations of quarks and leptons.
Neutrino masses in supersymmetric SU(3){sub c} x SU(3){sub L} x U(1){sub X} models
Rodriguez, J-Alexis; Duarte, J.
2008-11-23
The mass spectra and the superpotential of two different supersymetric models based on the gauge symmetry SU(3){sub C} x SU(3){sub L} x U(1){sub X}(331) without any exotic charges assigned to the fermionic spectra are studied. These two models have three families in different representations of the gauge group. In these kind of models, the diagonalization of the neutralino mass matrix allows that three light neutrinos get different mass values. Possible values for the neutrino masses are calculated covering the parameter space of the models. These values have to agree with the available data coming from the neutrino oscillations experiments. Therefore, a reduced space of parameters for the superpotential and the vacuum expectation values allowed in the framework of the 331 supersymetric models can be obtained.
Hiding neutrino mass in modified gravity cosmologies
NASA Astrophysics Data System (ADS)
Bellomo, Nicola; Bellini, Emilio; Hu, Bin; Jimenez, Raul; Pena-Garay, Carlos; Verde, Licia
2017-02-01
Cosmological observables show a dependence with the neutrino mass, which is partially degenerate with parameters of extended models of gravity. We study and explore this degeneracy in Horndeski generalized scalar-tensor theories of gravity. Using forecasted cosmic microwave background and galaxy power spectrum datasets, we find that a single parameter in the linear regime of the effective theory dominates the correlation with the total neutrino mass. For any given mass, a particular value of this parameter approximately cancels the power suppression due to the neutrino mass at a given redshift. The extent of the cancellation of this degeneracy depends on the cosmological large-scale structure data used at different redshifts. We constrain the parameters and functions of the effective gravity theory and determine the influence of gravity on the determination of the neutrino mass from present and future surveys.
The KATRIN Neutrino Mass Experiment
NASA Astrophysics Data System (ADS)
Parno, Diana; Katrin Collaboration
2017-01-01
While neutrino oscillation experiments have demonstrated that the particles have non-zero mass, the absolute neutrino mass scale is still unknown. The Karlsruhe Tritium Neutrino experiment (KATRIN) is designed to improve on previous laboratory limits by an order of magnitude, probing the effective neutrino mass with a sensitivity approaching 0.2 eV at 90% confidence via the kinematics of tritium beta decay. At the same time, KATRIN has the potential to scan for sterile neutrinos at eV and keV scales. After years of preparation, all major components are now on site and commissioning is underway. I will report on the current status of the experiment, including recent results and preparations for the introduction of tritium later this year. US participation in KATRIN is supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics under Award Number DE-FG02-97ER41020.
Gauged U(1) Lμ -Lτ model in light of muon g - 2 anomaly, neutrino mass and dark matter phenomenology
NASA Astrophysics Data System (ADS)
Patra, Sudhanwa; Rao, Soumya; Sahoo, Nirakar; Sahu, Narendra
2017-04-01
Gauged U(1) Lμ -Lτ model has been advocated for a long time in light of muon g - 2 anomaly, which is a more than 3σ discrepancy between the experimental measurement and the standard model prediction. We augment this model with three right-handed neutrinos (Ne ,Nμ ,Nτ) and a vector-like singlet fermion (χ) to explain simultaneously the non-zero neutrino masses and dark matter content of the Universe, while satisfying the anomalous muon g - 2 constraints. We find that the model suffers stringent constraints from the simultaneous explanation of neutrino trident production and muon g - 2 anomaly. In a large region of the parameter space, where contribution to muon g - 2 anomaly comes partially and yet not ruled out by neutrino trident production, the model can explain the positron excess, observed at PAMELA, Fermi-LAT and AMS-02 through dark matter annihilation, while satisfying the relic density and direct detection limits.
NASA Astrophysics Data System (ADS)
Ehrlich, R.
2016-12-01
Evidence is presented in support of an unconventional 3 + 3 model of the neutrino mass eigenstates with specific m2 > 0 and m2 < 0 masses. The two large m2 > 0 masses of the model were originally suggested based on a SN 1987A analysis, and they were further supported by several dark matter fits. The new evidence for one of the m2 > 0 mass values comes from an analysis of published data from the three most precise tritium β - decay experiments. The KATRIN experiment by virtue of a unique 3-part signature should either confirm or reject the model in its entirety.
Neutrino masses, leptogenesis, and sterile neutrino dark matter
NASA Astrophysics Data System (ADS)
Tsuyuki, Takanao
2014-07-01
We analyze a scenario in which the lightest heavy neutrino N1 is a dark matter candidate and the second-heaviest neutrino N2 decays producing a lepton number. If N1 were in thermal equilibrium, its energy density today would be much larger than that of the observed dark matter, so we consider energy injection by the decay of N2. In this paper, we show the parameters of this scenario that give the correct abundances of dark matter and baryonic matter and also induce the observed neutrino masses. This model can explain a possible sterile neutrino dark matter signal of M1=7 keV in the x-ray observation of x-ray multi-mirror mission.
Neutrino mixing matrix and masses from a generalized Friedberg-Lee model
NASA Astrophysics Data System (ADS)
Razzaghi, N.; Gousheh, S. S.
2014-02-01
The overall characteristics of the solar and atmospheric neutrino oscillation are approximately consistent with a tribimaximal form of the mixing matrix U of the lepton sector. Exact tribimaximal mixing leads to θ13=0. However, recent results from the Daya Bay and RENO experiments have established a nonzero value for θ13. Keeping the leading behavior of U as tribimaximal, we use a generalized Friedberg-Lee neutrino mass model along with a complementary ansatz to incorporate a nonzero θ13 along with CP violation. We generalize this model in two stages: In the first stage, we assume μ -τ symmetry and add imaginary components which leads to nonzero phases. In the second stage, we add a perturbation with real components which breaks the μ-τ symmetry, and this leads to a nonzero value for θ13. The combination of these two generalizations leads to CP violation. Using only two sets of the experimental data, we can fix all of the parameters of our model and predict not only values for the other experimental data, which agree well with the available data, but also the masses of neutrinos and the CP-violating phases and parameters. These predictions include the following: ⟨mνe⟩≈(0.033-0.037) eV, ⟨mνμ⟩≈(0.043-0.048) eV, ⟨mντ⟩≈(0.046-0.051) eV, and 59.21°≲δ ≲59.34°.
Direct determination of neutrino mass parameters at future colliders
Kadastik, M.; Raidal, M.; Rebane, L.
2008-06-01
If the observed light neutrino masses are induced by their Yukawa couplings to singlet right-handed neutrinos, the natural smallness of those makes direct collider tests of the electroweak scale neutrino mass mechanisms difficult in the simplest models. In the triplet Higgs seesaw scenario the smallness of light neutrino masses may come from the smallness of B-L breaking parameters, allowing sizable Yukawa couplings even for a TeV scale triplet. We show that, in this scenario, measuring the branching fractions of doubly charged Higgs to different same-charged lepton flavors at CERN LHC and/or ILC experiments will allow one to measure the neutrino mass parameters that neutrino oscillation experiments are insensitive to, including the neutrino mass hierarchy, lightest neutrino mass, and Majorana phases.
NASA Astrophysics Data System (ADS)
Liu, Zhen; Gu, Pei-Hong
2017-02-01
We extend some two Higgs doublet models, where the Yukawa couplings for the charged fermion mass generation only involve one Higgs doublet, by two singlet scalars respectively carrying a singly electric charge and a doubly electric charge. The doublet and singlet scalars together can mediate a two-loop diagram to generate a tiny Majorana mass matrix of the standard model neutrinos. Remarkably, the structure of the neutrino mass matrix is fully determined by the symmetric Yukawa couplings of the doubly charged scalar to the right-handed leptons. Meanwhile, a one-loop induced neutrinoless double beta decay can arrive at a testable level even if the electron neutrino has an extremely small Majorana mass. We also study other experimental constraints and implications including some rare processes and Higgs phenomenology.
Observational constraints on varying neutrino-mass cosmology
Geng, Chao-Qiang; Lee, Chung-Chi; Myrzakulov, R.; Sami, M.; Saridakis, Emmanuel N. E-mail: g9522545@oz.nthu.edu.tw E-mail: sami@iucaa.ernet.in
2016-01-01
We consider generic models of quintessence and we investigate the influence of massive neutrino matter with field-dependent masses on the matter power spectrum. In case of minimally coupled neutrino matter, we examine the effect in tracker models with inverse power-law and double exponential potentials. We present detailed investigations for the scaling field with a steep exponential potential, non-minimally coupled to massive neutrino matter, and we derive constraints on field-dependent neutrino masses from the observational data.
NASA Astrophysics Data System (ADS)
Samanta, Rome; Chakraborty, Mainak; Ghosal, Ambar
2016-03-01
We evaluate the Majorana phases for a general 3 × 3 complex symmetric neutrino mass matrix on the basis of Mohapatra-Rodejohann's phase convention using the three rephasing invariant quantities I12, I13 and I23 proposed by Sarkar and Singh. We find them interesting as they allow us to evaluate each Majorana phase in a model independent way even if one eigenvalue is zero. Utilizing the solution of a general complex symmetric mass matrix for eigenvalues and mixing angles we determine the Majorana phases for both the hierarchies, normal and inverted, taking into account the constraints from neutrino oscillation global fit data as well as bound on the sum of the three light neutrino masses (Σimi) and the neutrinoless double beta decay (ββ0ν) parameter |m11 |. This methodology of finding the Majorana phases is applied thereafter in some predictive models for both the hierarchical cases (normal and inverted) to evaluate the corresponding Majorana phases and it is shown that all the sub cases presented in inverted hierarchy section can be realized in a model with texture zeros and scaling ansatz within the framework of inverse seesaw although one of the sub cases following the normal hierarchy is yet to be established. Except the case of quasi degenerate neutrinos, the methodology obtained in this work is able to evaluate the corresponding Majorana phases, given any model of neutrino masses.
Splitting Neutrino masses and Showering into Sky
NASA Astrophysics Data System (ADS)
Fargion, D.; D'Armiento, D.; Lanciano, O.; Oliva, P.; Iacobelli, M.; de Sanctis Lucentini, P. G.; Grossi, M.; de Santis, M.
2007-06-01
Neutrino masses might be as light as a few time the atmospheric neutrino mass splitting. The relic cosmic neutrinos may cluster in wide Dark Hot Local Group Halo. High Energy ZeV cosmic neutrinos (in Z-Showering model) might hit relic ones at each mass in different resonance energies in our nearby Universe. This non-degenerated density and energy must split UHE Z-boson secondaries (in Z-Burst model) leading to multi injection of UHECR nucleons within future extreme AUGER energy. Secondaries of Z-Burst as neutral gamma, below a few tens EeV are better surviving local GZK cut-off and they might explain recent Hires BL-Lac UHECR correlations at small angles. A different high energy resonance must lead to Glashow's anti-neutrino showers while hitting electrons in matter. In water and ice it leads to isotropic light explosions. In air, Glashow's anti-neutrino showers lead to collimated and directional air-showers offering a new Neutrino Astronomy. Because of neutrino flavor mixing, astrophysical energetic tau neutrino above tens GeV must arise over atmospheric background. At TeV range is difficult to disentangle tau neutrinos from other atmospheric flavors. At greater energy around PeV, Tau escaping mountains and Earth and decaying in flight are effectively showering in air sky. These Horizontal showering is splitting by geomagnetic field in forked shapes. Such air-showers secondaries release amplified and beamed gamma bursts (like observed TGF), made also by muon and electron pair bundles, with their accompanying rich Cherenkov flashes. Also planet's largest (Saturn, Jupiter) atmosphere limbs offer an ideal screen for UHE GZK and Z-burst tau neutrino, because their largest sizes. Titan thick atmosphere and small radius are optimal for discovering up-going resonant Glashow resonant anti-neutrino electron showers. Detection from Earth of Tau, anti-Tau, anti-electron neutrino induced Air-showers by twin Magic Telescopes on top mountains, or space based detection on
Seesaw neutrino masses and mixing with extended democracy
NASA Astrophysics Data System (ADS)
Joaquim, F. R.
2001-05-01
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.
New development in radiative neutrino mass generation
NASA Astrophysics Data System (ADS)
Julio
2014-10-01
We present a simple and predictive model of radiative neutrino masses. It is a special case of the Zee model with a family-dependent Z4 symmetry acting on the leptons. A variety of predictions follow: The hierarchy of neutrino masses must be inverted; the lightest neutrino mass is extremely small and calculable; one of the neutrino mixing angles is determined in terms of the other two; the phase parameters take CP-conserving values with δCP = π and the effective mass in neutrinoless double beta decay lies in a narrow range, mββ =(17.6-18.5) meV. The ratio of vacuum expectation values of the two Higgs doublets, tan β, is determined to be either 1.9 or 0.19 from neutrino oscillation data. Flavor-conserving and flavor-changing couplings of the Higgs doublets are also determined from neutrino data. The non-standard neutral Higgs bosons, if they are moderately heavy, decay significantly into μ and τ with prescribed branching ratios. Observable rates for the decays μ → eγ and τ → 3μ are predicted if these scalars have masses in the range of 150-500 GeV.
Right-handed neutrinos at CERN LHC and the mechanism of neutrino mass generation
Kersten, Joern; Smirnov, Alexei Yu.
2007-10-01
We consider the possibility to detect right-handed neutrinos, which are mostly singlets of the standard model gauge group, at future accelerators. Substantial mixing of these neutrinos with the active neutrinos requires a cancellation of different contributions to the light neutrino mass matrix at the level of 10{sup -8}. We discuss possible symmetries behind this cancellation and argue that for three right-handed neutrinos they always lead to conservation of total lepton number. Light neutrino masses can be generated by small perturbations violating these symmetries. In the most general case, LHC physics and the mechanism of neutrino mass generation are essentially decoupled; with additional assumptions, correlations can appear between collider observables and features of the neutrino mass matrix.
Probing radiative neutrino mass models using trilepton channel at the LHC
NASA Astrophysics Data System (ADS)
Cherigui, Dounia; Guella, Chahrazed; Ahriche, Amine; Nasri, Salah
2016-11-01
In this work, we probe a class of neutrino mass models through the lepton flavor violating interactions of a singlet charged scalar, S± at the LHC proton-proton collisions with 8 TeV and 14 TeV energies. This scalar couples to the leptons and induces many processes such as pp →ℓ±ℓ±ℓ∓ +E̸T. In our analysis we discuss the opposite sign same flavor leptons signal, as well as the background free channel with the tau contribution which can enhance the signal/background ratio for center of mass energies √{ s} = 8 TeV and √{ s} = 14 TeV.
Neutrino Masses and Mixing from Supersymmetric Inflation
NASA Astrophysics Data System (ADS)
Lazarides, G.
A supersymmetric model based on a l-right symmetric gauge group is proposed where hybrid inflation, baryogenesis and neutrino oscillations are linked.This scheme, supplemented by a familiar ansatz for the neutrino Dirac masses and mixing of the two heaviest families and with the MSW resolution of the solar neutrino puzzle, implies that 1
Status of neutrino mass experiments
Fackler, O.
1985-12-01
In 1980 two experiments ignited a fertile field of research the determination of the neutrino masses. Subsequently, over 35 experiments using a variety of techniques have probed or are probing this question. Primarily I will discuss electron antineutrino (hereafter referred to as neutrino) mass experiments. However, let me begin in Section I to discuss astronomical and terrestrial observations which motivated these experiments. In Section II, I will quote limits from muon and tau mass determinations. These limits are more thoroughly discussed in other papers. I will continue by describing the four approaches used to measure the electron neutrino mass. In Section III, tritium beta decay mass determinations will be reviewed. This section includes a general summary of previous experimental results, and discussion of the major ongoing experiments. Section IV offers concluding remarks. 24 refs., 24 figs.
Constraining dynamical neutrino mass generation with cosmological data
NASA Astrophysics Data System (ADS)
Koksbang, S. M.; Hannestad, S.
2017-09-01
We study models in which neutrino masses are generated dynamically at cosmologically late times. Our study is purely phenomenological and parameterized in terms of three effective parameters characterizing the redshift of mass generation, the width of the transition region, and the present day neutrino mass. We also study the possibility that neutrinos become strongly self-interacting at the time where the mass is generated. We find that in a number of cases, models with large present day neutrino masses are allowed by current CMB, BAO and supernova data. The increase in the allowed mass range makes it possible that a non-zero neutrino mass could be measured in direct detection experiments such as KATRIN. Intriguingly we also find that there are allowed models in which neutrinos become strongly self-interacting around the epoch of recombination.
Determining the neutrino mass hierarchy with cosmology
De Bernardis, Francesco; Kitching, Thomas D.; Heavens, Alan; Melchiorri, Alessandro
2009-12-15
The combination of current large-scale structure and cosmic microwave background anisotropies data can place strong constraints on the sum of the neutrino masses. Here we show that future cosmic shear experiments, in combination with cosmic microwave background constraints, can provide the statistical accuracy required to answer questions about differences in the mass of individual neutrino species. Allowing for the possibility that masses are nondegenerate we combine Fisher matrix forecasts for a weak lensing survey like Euclid with those for the forthcoming Planck experiment. Under the assumption that neutrino mass splitting is described by a normal hierarchy we find that the combination Planck and Euclid will possibly reach enough sensitivity to put a constraint on the mass of a single species. Using a Bayesian evidence calculation we find that such future experiments could provide strong evidence for either a normal or an inverted neutrino hierarchy. Finally we show that if a particular neutrino hierarchy is assumed then this could bias cosmological parameter constraints, for example, the dark energy equation of state parameter, by > or approx. 1{sigma}, and the sum of masses by 2.3{sigma}. We finally discuss the impact of uncertainties on the theoretical modeling of nonlinearities. The results presented in this analysis are obtained under an approximation to the nonlinear power spectrum. This significant source of uncertainty needs to be addressed in future work.
Hannestad, Steen
2005-11-25
At present, cosmology provides the nominally strongest constraint on the masses of standard model neutrinos. However, this constraint is extremely dependent on the nature of the dark energy component of the Universe. When the dark energy equation of state parameter is taken as a free (but constant) parameter, the neutrino mass bound is sigma m(v) < or = 1.48 eV (95% C.L.), compared with sigma m(v) < or = 0.65 eV (95% C.L.) in the standard model where the dark energy is in the form of a cosmological constant. This has important consequences for future experiments aimed at the direct measurement of neutrino masses. We also discuss prospects for future cosmological measurements of neutrino masses.
The KATRIN neutrino mass experiment
NASA Astrophysics Data System (ADS)
Wolf, Joachim; Katrin Collaboration
2010-11-01
The Karlsruhe Tritium Neutrino experiment (KATRIN) aims to determine the electron neutrino mass from tritium decay in a model-independent way, by a kinematic measurement of the energy of β-electrons. The unprecedented sensitivity of 0.2 eV/c2 will improve present limits by one order of magnitude. The decay electrons will originate from a 10 m long windowless gaseous tritium source. Super-conducting magnets will guide the electrons through a differential and cryogenic pumping section to the electro-static tandem spectrometer (MAG-E-filter), where the kinetic energy will be measured. The experiment is presently being built at the Forschungszentrum Karlsruhe by an international collaboration of more than 120 scientists. The largest component, the 1240 m3 main spectrometer, was delivered end of 2006 and first commissioning tests have been performed. This paper gives an overview of the goals and technological challenges of the experiment and reports on the progress in commissioning first major components. The start of first measurements is expected in 2012.
Neutrino mass as the probe of intermediate mass scales
Senjanovic, G.
1980-01-01
A discussion of the calculability of neutrino mass is presented. The possibility of neutrinos being either Dirac or Majorana particles is analyzed in detail. Arguments are offered in favor of the Majorana case: the smallness of neutrino mass is linked to the maximality of parity violation in weak interactions. It is shown how the measured value of neutrino mass would probe the existence of an intermediate mass scale, presumably in the TeV region, at which parity is supposed to become a good symmetry. Experimental consequences of the proposed scheme are discussed, in particular the neutrino-less double ..beta.. decay, where observation would provide a crucial test of the model, and rare muon decays such as ..mu.. ..-->.. e..gamma.. and ..mu.. ..-->.. ee anti e. Finally, the embedding of this model in an O(10) grand unified theory is analyzed, with the emphasis on the implications for intermediate mass scales that it offers. It is concluded that the proposed scheme provides a distinct and testable alternative for understanding the smallness of neutrino mass. 4 figures.
Neutrino mass implications for muon decay parameters
Erwin, Rebecca J.; Kile, Jennifer; Ramsey-Musolf, Michael J.; Wang Peng
2007-02-01
We use the scale of neutrino mass and naturalness considerations to obtain model-independent expectations for the magnitude of possible contributions to muon decay Michel parameters from new physics above the electroweak symmetry-breaking scale. Focusing on Dirac neutrinos, we obtain a complete basis of dimension four and dimension six effective operators that are invariant under the gauge symmetry of the standard model and that contribute to both muon decay and neutrino mass. We show that - in the absence of fine tuning - the most stringent neutrino-mass naturalness bounds on chirality-changing vector operators relevant to muon decay arise from one-loop operator mixing. The bounds we obtain on their contributions to the Michel parameters are 2 orders of magnitude stronger than bounds previously obtained in the literature. In addition, we analyze the implications of one-loop matching considerations and find that the expectations for the size of various scalar and tensor contributions to the Michel parameters are considerably smaller than derived from previous estimates of two-loop operator mixing. We also show, however, that there exist gauge-invariant operators that generate scalar and tensor contributions to muon decay but whose flavor structure allows them to evade neutrino-mass naturalness bounds. We discuss the implications of our analysis for the interpretation of muon-decay experiments.
Review of direct neutrino mass experiments
Dragoun, O.
2015-10-28
Advantages and drawbacks of the kinematic methods of the neutrino mass determination are discussed. The meaning of the effective neutrino mass, resulting from measurements of the endpoint region of β-spectra is clarified. Current experimental constraints on the mass of active as well as sterile neutrinos are presented. Several new experiments are briefly outlined.
Neutrinos: in and out of the standard model
Parke, Stephen; /Fermilab
2006-07-01
The particle physics Standard Model has been tremendously successful in predicting the outcome of a large number of experiments. In this model Neutrinos are massless. Yet recent evidence points to the fact that neutrinos are massive particles with tiny masses compared to the other particles in the Standard Model. These tiny masses allow the neutrinos to change flavor and oscillate. In this series of Lectures, I will review the properties of Neutrinos In the Standard Model and then discuss the physics of Neutrinos Beyond the Standard Model. Topics to be covered include Neutrino Flavor Transformations and Oscillations, Majorana versus Dirac Neutrino Masses, the Seesaw Mechanism and Leptogenesis.
Beyond the Standard Model: The Weak Scale, Neutrino Mass, and the Dark Sector
Weiner, Neal
2010-12-20
The goal of this proposal was to advance theoretical studies into questions of collider physics at the weak scale, models and signals of dark matter, and connections between neutrino mass and dark energy. The project was a significant success, with a number of developments well beyond what could have been anticipated at the outset. A total of 35 published papers and preprints were produced, with new ideas and signals for LHC physics and dark matter experiments, in particular. A number of new ideas have been found on the possible indirect signals of models of dark matter which relate to the INTEGRAL signal of astrophysical positron production, high energy positrons seen at PAMELA and Fermi, studies into anomalous gamma rays at Fermi, collider signatures of sneutrino dark matter, scenarios of Higgs physics arising in SUSY models, the implications of galaxy cluster surveys for photon-axion conversion models, previously unconsidered collider phenomenology in the form of 'lepton jets' and a very significant result for flavor physics in supersymmetric theories. Progress continues on all fronts, including development of models with dramatic implications for direct dark matter searches, dynamics of dark matter with various excited states, flavor physics, and consequences of modified missing energy signals for collider searches at the LHC.
Renormalizable model for neutrino mass, dark matter, muon g - 2 and 750 GeV diphoton excess
NASA Astrophysics Data System (ADS)
Okada, Hiroshi; Yagyu, Kei
2016-05-01
We discuss a possibility to explain the 750 GeV diphoton excess observed at the LHC in a three-loop neutrino mass model which has a similar structure to the model by Krauss, Nasri and Trodden. Tiny neutrino masses are naturally generated by the loop effect of new particles with their couplings and masses to be of order 0.1-1 and TeV, respectively. The lightest right-handed neutrino, which runs in the three-loop diagram, can be a dark matter candidate. In addition, the deviation in the measured value of the muon anomalous magnetic moment from its prediction in the standard model can be compensated by one-loop diagrams with exotic multi-charged leptons and scalar bosons. For the diphoton event, an additional isospin singlet real scalar field plays the role to explain the excess by taking its mass of 750 GeV, where it is produced from the gluon fusion production via the mixing with the standard model like Higgs boson. We find that the cross section of the diphoton process can be obtained to be a few fb level by taking the masses of new charged particles to be about 375 GeV and related coupling constants to be order 1.
Higgs Boson Mass, Neutrino Oscillations and Inflation
Shafi, Qaisar
2008-11-23
Finding the Standard Model scalar (Higgs) boson is arguably the single most important mission of the LHC. I review predictions for the Higgs boson mass based on stability and perturbativity arguments, taking into account neutrino oscillations. Primordial inflation based on the Coleman-Weinberg potential is briefly discussed.
Neutrino masses, Majorons, and muon decay
Santamaria, A.; Bernabeu, J.; Pich, A.
1987-09-01
The contributions to the parameters xi, delta, rho, and eta in muon decay coming from double Majoron emission, Majorana neutrino masses, and effects of charged scalars are evaluated in the scalar-triplet model. The relevance of these effects for planned experiments is discussed.
Neutrino masses, mixing, moments, and matter
Marciano, W.J.
1988-01-01
The present status of neutrino masses, mixing, and electromagnetic moments is surveyed. Potential enhancements of neutrino oscillations, decay, and spin-flavor precession due to their interactions with matter are described.
Neutrino mass from M theory SO(10)
NASA Astrophysics Data System (ADS)
Acharya, Bobby S.; Bożek, Krzysztof; Romão, Miguel Crispim; King, Stephen F.; Pongkitivanichkul, Chakrit
2016-11-01
We study the origin of neutrino mass from SO(10) arising from M Theory compactified on a G 2-manifold. This is linked to the problem of the breaking of the extra U(1) gauge group, in the SU(5) × U(1) subgroup of SO(10), which we show can achieved via a (generalised) Kolda-Martin mechanism. The resulting neutrino masses arise from a combination of the seesaw mechanism and induced R-parity breaking contributions. The rather complicated neutrino mass matrix is analysed for one neutrino family and it is shown how phenomenologically acceptable neutrino masses can emerge.
Introduction to direct neutrino mass measurements and KATRIN
NASA Astrophysics Data System (ADS)
Thümmler, T.; Katrin Collaboration
2012-08-01
The properties of neutrinos and especially their rest mass play an important role at the intersections of cosmology, particle physics and astroparticle physics. At present there are two complementary approaches to address this topic in laboratory experiments. The search for neutrinoless double beta decay probes whether neutrinos are Majorana particles and determines an effective neutrino mass value. On the other hand experiments such as MARE, KATRIN and the recently proposed Project 8 will investigate the spectral shape of β-decay electrons close to their kinematic endpoint in order to determine the neutrino rest mass with a model-independent method. Here, because of neutrino flavour mixing, the neutrino mass appears as an average of all neutrino mass eigenstates contributing to the electron neutrino. The KArlsruhe TRItium Neutrino experiment (KATRIN) is currently the experiment in the most advanced status of commissioning. It combines an ultra-luminous molecular windowless gaseous tritium source with an integrating high-resolution spectrometer of MAC-E filter type. It will investigate the neutrino rest mass with 0.2 eV/c (90% C.L.) sensitivity and allow β spectroscopy close to the T endpoint at 18.6 keV with unprecedented precision.
Neutrino mass and proton lifetime in a realistic supersymmetric SO(10) model
NASA Astrophysics Data System (ADS)
Severson, Matthew
This work presents a complete analysis of fermion fitting and proton decay in a supersymmetric SO(10) model previously suggested by Dutta, Mimura, and Mohapatra. A key question in any grand unified theory is whether it satisfies the stringent experimental lower limits on the partial lifetimes of the proton. In more generic models, substantial fine-tuning is required among GUT-scale parameters to satisfy the limits. In the proposed model, the 10, 1¯2¯6¯, and 20 Yukawa couplings contributing to fermion masses have restricted textures intended to give favorable results for proton lifetime, while still giving rise to a realistic fermion sector, without the need for fine-tuning, even for large beta, and for either type-I or type-II dominance in the neutrino mass matrix. In this thesis, I investigate the above hypothesis at a strict numerical level of scrutiny; I obtain a valid fit for the entire fermion sector for both types of seesaw dominance, including theta13 in good agreement with the most recent data. For the case with type-II seesaw, I find that, using the Yukawa couplings fixed by the successful fermion sector fit, proton partial lifetime limits are readily satisfied for all but one of the pertinent decay modes for nearly arbitrary values of the triplet-Higgs mixing parameters, with the K+v¯ mode requiring a minor ∂(10--1) cancellation in order to satisfy its limit. I also find a maximum partial lifetime for that mode of τ( K+v¯) ˜ 1036,years. For the type-I seesaw case, I find that K+ v¯ decay mode is satisfied for any values of the triplet mixing parameters giving no major enhancement, and all other modes are easily satisfied for arbitrary mixing values; I also find a maximum partial lifetime for K+v¯ of nearly 1036years, which is largely sub-dominant to gauge boson decay channels.
Masses, mixing angles and phases of general Majorana neutrino mass matrix
NASA Astrophysics Data System (ADS)
Adhikary, Biswajit; Chakraborty, Mainak; Ghosal, Ambar
2013-10-01
General Majorana neutrino mass matrix is complex symmetric and for three generations of neutrinos it contains 12 real parameters. We diagonalize this general neutrino mass matrix and express the three neutrino masses, three mixing angles, one Dirac CP phase and two Majorana phases (removing three unphysical phases) in terms of the neutrino mass matrix elements. We apply the results in the context of a neutrino mass matrix derived from a broken cyclic symmetry invoking type-I seesaw mechanism. Phenomenological study of the above mass matrix allows enough parameter space to satisfy the neutrino oscillation data with only 10% breaking of this symmetry. In this model only normal mass hierarchy is allowed. In addition, the Dirac CP phase and the Majorana phases are numerically estimated. Σ m i and | m νee | are also calculated.
Neutrino oscillations and the seesaw origin of neutrino mass
NASA Astrophysics Data System (ADS)
Miranda, O. G.; Valle, J. W. F.
2016-07-01
The historical discovery of neutrino oscillations using solar and atmospheric neutrinos, and subsequent accelerator and reactor studies, has brought neutrino physics to the precision era. We note that CP effects in oscillation phenomena could be difficult to extract in the presence of unitarity violation. As a result upcoming dedicated leptonic CP violation studies should take into account the non-unitarity of the lepton mixing matrix. Restricting non-unitarity will shed light on the seesaw scale, and thereby guide us towards the new physics responsible for neutrino mass generation.
Decaying majoron dark matter and neutrino masses
Lattanzi, Massimiliano
2008-01-03
We review our recent proposal of the majoron as a suitable warm dark matter candidate. The majoron is the Goldstone boson associated to the spontaneous breaking of ungauged lepton number, one of the mechanisms proposed to give rise to neutrino masses. The majoron can acquire a mass through quantum gravity effects, and can possibly account for the observed dark matter component of the Universe. We present constraints on the majoron lifetime, mass and abundance obtained by the analysis of the cosmic microwave background data. We find that, in the case of thermal production, the limits for the majoron mass read 0.12 keV
Constraining absolute neutrino masses via detection of galactic supernova neutrinos at JUNO
Lu, Jia-Shu; Cao, Jun; Li, Yu-Feng; Zhou, Shun E-mail: caoj@ihep.ac.cn E-mail: zhoush@ihep.ac.cn
2015-05-01
A high-statistics measurement of the neutrinos from a galactic core-collapse supernova is extremely important for understanding the explosion mechanism, and studying the intrinsic properties of neutrinos themselves. In this paper, we explore the possibility to constrain the absolute scale of neutrino masses m{sub ν} via the detection of galactic supernova neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO) with a 20 kiloton liquid-scintillator detector. In assumption of a nearly-degenerate neutrino mass spectrum and a normal mass ordering, the upper bound on the absolute neutrino mass is found to be m{sub ν} < (0.83 ± 0.24) eV at the 95% confidence level for a typical galactic supernova at a distance of 10 kpc, where the mean value and standard deviation are shown to account for statistical fluctuations. For comparison, we find that the bound in the Super-Kamiokande experiment is m{sub ν} < (0.94 ± 0.28) eV at the same confidence level. However, the upper bound will be relaxed when the model parameters characterizing the time structure of supernova neutrino fluxes are not exactly known, and when the neutrino mass ordering is inverted.
Constraining absolute neutrino masses via detection of galactic supernova neutrinos at JUNO
Lu, Jia-Shu; Cao, Jun; Li, Yu-Feng; Zhou, Shun
2015-05-26
A high-statistics measurement of the neutrinos from a galactic core-collapse supernova is extremely important for understanding the explosion mechanism, and studying the intrinsic properties of neutrinos themselves. In this paper, we explore the possibility to constrain the absolute scale of neutrino masses m{sub ν} via the detection of galactic supernova neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO) with a 20 kiloton liquid-scintillator detector. In assumption of a nearly-degenerate neutrino mass spectrum and a normal mass ordering, the upper bound on the absolute neutrino mass is found to be m{sub ν}<(0.83±0.24) eV at the 95% confidence level for a typical galactic supernova at a distance of 10 kpc, where the mean value and standard deviation are shown to account for statistical fluctuations. For comparison, we find that the bound in the Super-Kamiokande experiment is m{sub ν}<(0.94±0.28) eV at the same confidence level. However, the upper bound will be relaxed when the model parameters characterizing the time structure of supernova neutrino fluxes are not exactly known, and when the neutrino mass ordering is inverted.
Testable two-loop radiative neutrino mass model based on an LLQd c Qd c effective operator
NASA Astrophysics Data System (ADS)
Angel, Paul W.; Cai, Yi; Rodd, Nicholas L.; Schmidt, Michael A.; Volkas, Raymond R.
2013-10-01
A new two-loop radiative Majorana neutrino mass model is constructed from the gauge-invariant effective operator L i L j Q k d c Q l d c ɛ ik ɛ jl that violates lepton number conservation by two units. The ultraviolet completion features two scalar leptoquark flavors and a color-octet Majorana fermion. We show that there exists a region of parameter space where the neutrino oscillation data can be fitted while simultaneously meeting flavor-violation and collider bounds. The model is testable through lepton flavor-violating processes such as μ → eγ, μ → eee, and μN → eN conversion, as well as collider searches for the scalar leptoquarks and color-octet fermion. We computed and compiled a list of necessary Passarino-Veltman integrals up to boxes in the approximation of vanishing external momenta and made them available as a Mathematica package, denoted as ANT.
Neutrino masses and scalar singlet dark matter
NASA Astrophysics Data System (ADS)
Bhattacharya, Subhaditya; Jana, Sudip; Nandi, S.
2017-03-01
We propose a simple extension of the Standard Model (SM) which has a viable dark matter (DM) candidate and can explain the generation of tiny neutrino masses. The DM is an electroweak (EW) singlet scalar S , odd under an imposed exact Z2 symmetry, that interacts with the SM through the "Higgs portal" coupling, while all other particles are even under Z2. The model also has an EW isospin 3 /2 scalar Δ and a pair of EW isospin vectors Σ and Σ ¯, which are responsible for generating tiny neutrino mass via the effective dimension-seven operator. Thanks to the additional interactions with Δ , the scalar singlet DM S survives a large region of parameter space by relic density constraints from WMAP/Planck and direct search bounds from updated LUX data. Constraints on the model from the LHC are also discussed.
Searching for radiative neutrino mass generation at the LHC
NASA Astrophysics Data System (ADS)
Volkas, Raymond R.
2015-04-01
In this talk (talk given at the International Conference on Massive Neutrinos, Singapore, 9-13 February 2015), I describe the general characteristics of radiative neutrino mass models that can be probed at the LHC. I then cover the specific constraints on a new, explicit model of this type.
Neutrino oscillations from Dirac and Majorana masses
Ring, D.
1997-05-01
We present a scenario of neutrino masses and mixing angles. Each generation includes a sterile right-handed neutrino in addition to the usual left-handed one. We assume a hierarchy in their Dirac masses similar to, but much larger than, the hierarchies in the quarks and charged leptons. In addition, we include a Majorana mass term for the sterile neutrinos only. These assumptions prove sufficient to accommodate scales of mass differences and mixing angles consistent with all existing neutrino oscillation data. {copyright} {ital 1997} {ital The American Physical Society}
Probing the Absolute Mass Scale of Neutrinos
Prof. Joseph A. Formaggio
2011-10-12
The experimental efforts of the Neutrino Physics Group at MIT center primarily around the exploration of neutrino mass and its significance within the context of nuclear physics, particle physics, and cosmology. The group has played a prominent role in the Sudbury Neutrino Observatory, a neutrino experiment dedicated to measure neutrino oscillations from 8B neutrinos created in the sun. The group is now focusing its efforts in the measurement of the neutrino mass directly via the use of tritium beta decay. The MIT group has primary responsibilities in the Karlsruhe Tritium Neutrino mass experiment, expected to begin data taking by 2013. Specifically, the MIT group is responsible for the design and development of the global Monte Carlo framework to be used by the KATRIN collaboration, as well as responsibilities directly associated with the construction of the focal plane detector. In addition, the MIT group is sponsoring a new research endeavor for neutrino mass measurements, known as Project 8, to push beyond the limitations of current neutrino mass experiments.
Hybrid method to resolve the neutrino mass hierarchy by supernova (anti)neutrino induced reactions
Vale, D.; Rauscher, T.; Paar, N. E-mail: Thomas.Rauscher@unibas.ch
2016-02-01
We introduce a hybrid method to determine the neutrino mass hierarchy by simultaneous measurements of responses of at least two detectors to antineutrino and neutrino fluxes from accretion and cooling phases of core-collapse supernovae. The (anti)neutrino-nucleus cross sections for {sup 56}Fe and {sup 208}Pb are calculated in the framework of the relativistic nuclear energy density functional and weak interaction Hamiltonian, while the cross sections for inelastic scattering on free protons p(ν-bar {sub e},e{sup +})n are obtained using heavy-baryon chiral perturbation theory. The modelling of (anti)neutrino fluxes emitted from a protoneutron star in a core-collapse supernova include collective and Mikheyev-Smirnov-Wolfenstein effects inside the exploding star. The particle emission rates from the elementary decay modes of the daughter nuclei are calculated for normal and inverted neutrino mass hierarchy. It is shown that simultaneous use of (anti)neutrino detectors with different target material allows to determine the neutrino mass hierarchy from the ratios of ν{sub e}- and ν-bar {sub e}-induced particle emissions. This hybrid method favors neutrinos from the supernova cooling phase and the implementation of detectors with heavier target nuclei ({sup 208}Pb) for the neutrino sector, while for antineutrinos the use of free protons in mineral oil or water is the appropriate choice.
Nomura, Takaaki; Okada, Hiroshi; Okada, Nobuchika
2016-09-22
Here, we propose a radiative seesaw model at the three-loop level, in which quarks, leptons, leptoquark bosons, and a Majorana fermion of dark matter candidate are involved in the neutrino loop. When analyzing neutrino oscillation data includes all possible constraints such as flavor changing neutral currents, lepton flavor violations, upper/lower bound on the mass of leptoquark from the collider physics, and the measured relic density of the dark matter, we show the allowed region to satisfy all the data/constraints.
The modified correlation mass method for detecting neutrino mass from astrophysical neutrino bursts
NASA Technical Reports Server (NTRS)
Chan, Kwing L.; Chiu, Hong-Yee; Kondo, Yoji
1989-01-01
A modified correlation mass method for calculating the value of a possible neutrino mass from neutrino bursts of astrophysical origin is proposed which can more sensitively detect small neutrino masses than previous methods. Application of the method to the neutrinos detected from SN 1987 A yields a value of 3.6 + or - 0.3 eV for the neutrino mass energy with a confidence level of 97 percent. Assuming a neutrino mass of 3.6 eV, and transforming all of the detected neutrino events back to the point of emission, it is shown that bursts are composed of a short initial pulse (which lasts for about 0.1 sec and contains 30-40 percent of the total neutrinos) and an extended emission lasting for about 10 sec.
Neutrino mixing, CP and T violation, and textures in four-neutrino models
Barger, V.; Dai, Y.; Whisnant, K.; Young, B.
1999-06-01
We examine the prospects for determining the neutrino mixing matrix and for observing CP and T violation in neutrino oscillations in four-neutrino models. We focus on a general class of four-neutrino models with two pairs of nearly degenerate mass eigenstates separated by approximately 1 eV, which can describe the solar, atmospheric and LSND neutrino data. We present a general parametrization of these models and discuss in detail the determination of the mixing parameters and the mass matrix texture from current and future neutrino data in the case where {nu}{sub e} and {nu}{sub {mu}} each mix primarily with one other neutrino. We find that measurable CP or T violation in long-baseline experiments, with amplitude at the level of the LSND signal, is possible given current experimental constraints. Also, additional oscillation effects in short- and long-baseline experiments may be measurable in many cases. We point out that, given separate scales for the mass-squared differences of the solar and atmospheric oscillations, observable CP or T violation effects in neutrino oscillations signal the existence of a sterile neutrino. We examine several textures of the neutrino mass matrix and determine which textures can have measurable CP or T violation in neutrino oscillations in long-baseline experiments. We also briefly discuss some possible origins of the neutrino mass terms in straightforward extensions of the standard model. {copyright} {ital 1999} {ital The American Physical Society}
The experimental status of neutrino masses and mixings
Robertson, R.G.H.
1992-01-01
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 indications that neutrino oscillations are occurring. Other evidence for new physics is less consistent and convincing.
Neutrino mass and mixing, and non-accelerator experiments
Robertson, R.G.H.
1992-01-01
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.
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).
Mass varying neutrinos, symmetry breaking, and cosmic acceleration
NASA Astrophysics Data System (ADS)
Sadjadi, H. Mohseni; Anari, V.
2017-06-01
We introduce a new proposal for the onset of cosmic acceleration based on mass varying neutrinos. When massive neutrinos become nonrelativistic, the Z2 symmetry breaks, and the quintessence potential becomes positive from its initially zero value. This positive potential behaves like a cosmological constant at the present era and drives the Universe's acceleration during the slow roll evolution of the quintessence. In contrast to Λ CDM model, the dark energy in our model is dynamical, and the acceleration is not persistent. Contrary to some of the previous models of dark energy with mass varying neutrinos, we do not use the adiabaticity condition, which leads to instability.
PINGU sensitivity to neutrino mass hierarchy
Groß, Andreas; Collaboration: IceCube-PINGU Collaboration
2014-11-18
Determination of the neutrino mass hierarchy (NMH) is among the most fundamental questions in particle physics. Recent measurements of 1) a large mixing angle between the first and the third neutrino mass eigenstates and 2) the first observation of atmospheric neutrino oscillations at tens of GeV with neutrino telescopes, open the intriguing new possibility to exploit matter effects in neutrino oscillation to determine the neutrino mass hierarchy. A further extension of IceCube/DeepCore called PINGU (Precision IceCube Next Generation Upgrade) has been recently envisioned with the ultimate goal to measure neutrino mass hierarchy. PINGU would consist of additional IceCube-like strings of detectors deployed in the deepest and cleanest ice in the center of IceCube. More densely deployed instrumentation would provide a threshold substantially below 10 GeV and enhance the sensitivity to the mass hierarchy signal in atmospheric neutrinos. Here we discuss an estimate of the PINGU sensitivity to the mass hierarchy determined using an approximation with an Asimov dataset and an oscillation parameter fit.
Cosmology in Mirror Twin Higgs and neutrino masses
Chacko, Zackaria; Craig, Nathaniel; Fox, Patrick J.; ...
2017-07-06
We explore a simple solution to the cosmological challenges of the original Mirror Twin Higgs (MTH) model that leads to interesting implications for experiment. We consider theories in which both the standard model and mirror neutrinos acquire masses through the familiar seesaw mechanism, but with a low right-handed neutrino mass scale of order a few GeV. In thesemore » $$\
Revisiting the texture zero neutrino mass matrices
NASA Astrophysics Data System (ADS)
Singh, Madan; Ahuja, Gulsheen; Gupta, Manmohan
2016-12-01
In the light of refined and large measurements of the reactor mixing angle θ, 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 δ and Majorana phases ρ and σ.
Distinguishing neutrino mass hierarchies using dark matter annihilation signals at IceCube
Allahverdi, Rouzbeh; Dutta, Bhaskar; Ghosh, Dilip Kumar; Knockel, Bradley; Saha, Ipsita
2015-12-01
We explore the possibility of distinguishing neutrino mass hierarchies through the neutrino signal from dark matter annihilation at neutrino telescopes. We consider a simple extension of the standard model where the neutrino masses and mixing angles are obtained via the type-II seesaw mechanism as an explicit example. We show that future extensions of IceCube neutrino telescope may detect the neutrino signal from DM annihilation at the Galactic Center and inside the Sun, and differentiate between the normal and inverted mass hierarchies, in this model.
Status of the neutrino mass experiment KATRIN
Bornschein, L.; Bornschein, B.; Sturm, M.; Roellig, M.; Priester, F.
2015-03-15
The most sensitive way to determine the neutrino mass scale without further assumptions is to measure the shape of a tritium beta spectrum near its kinematic end-point. Tritium is the nucleus of choice because of its low endpoint energy, superallowed decay and simple atomic structure. Within an international collaboration the Karlsruhe Tritium Neutrino experiment (KATRIN) is currently being built up at KIT. KATRIN will allow a model-independent measurement of the neutrino mass scale with an expected sensitivity of 0.2 eV/c{sup 2} (90% CL). KATRIN will use a source of ultrapure molecular tritium. This contribution presents the status of the KATRIN experiment, thereby focusing on its Calibration and Monitoring System (CMS), which is the last component being subject to research/development. After a brief overview of the KATRIN experiment in Section II the CMS is introduced in Section III. In Section IV the Beta Induced X-Ray Spectroscopy (BIXS) as method of choice to monitor the tritium activity of the KATRIN source is described and first results are presented.
Neutrino jets from high-mass WR gauge bosons in TeV-scale left-right symmetric models
NASA Astrophysics Data System (ADS)
Mitra, Manimala; Ruiz, Richard; Scott, Darren J.; Spannowsky, Michael
2016-11-01
We reexamine the discovery potential at hadron colliders of high-mass right-handed (RH) gauge bosons WR—an inherent ingredient of left-right symmetric models (LRSM). We focus on the regime where the WR is very heavy compared to the heavy Majorana neutrino N , and we investigate an alternative signature for WR→N decays. The produced neutrinos are highly boosted in this mass regime. Subsequently, their decays via off-shell WR bosons to jets, i.e., N →ℓ±jj, are highly collimated, forming a single neutrino jet (jN). The final-state collider signature is then ℓ±jN, instead of the widely studied ℓ±ℓ±j j . Present search strategies are not sensitive to this hierarchical mass regime due to the breakdown of the collider signature definition. We take into account QCD corrections beyond next-to-leading order (NLO) that are important for high-mass Drell-Yan processes at the 13 TeV Large Hadron Collider (LHC). For the first time, we evaluate WR production at NLO with threshold resummation at next-to-next-to-leading logarithm (NNLL) matched to the threshold-improved parton distributions. With these improvements, we find that a WR of mass MWR=3 (4 )[5 ] TeV and mass ratio of (mN/MWR)<0.1 can be discovered with a 5 - 6 σ statistical significance at 13 TeV after 10 (100 )[2000 ] fb-1 of data. Extending the analysis to the hypothetical 100 TeV Very Large Hadron Collider (VLHC), 5 σ can be obtained for WR masses up to MW R=15 (30 ) with approximately 100 fb-1 (10 ab-1 ). Conversely, with 0.9 (10 )[150 ] fb-1 of 13 TeV data, MWR<3 (4 )[5 ] TeV and (mN/MWR)<0.1 can be excluded at 95% C.L.; with 100 fb-1 (2.5 ab-1 ) of 100 TeV data, MW R<22 (33 ) TeV can be excluded.
Pseudo Dirac neutrinos in the seesaw model
NASA Astrophysics Data System (ADS)
Dutta, Gautam; Joshipura, Anjan S.
1995-04-01
A specific class of textures for the Dirac and Majorana mass matrices in the seesaw model leading to a pair of almost degenerate neutrinos is discussed. These textures can be obtained by imposing a horizontal U(1) symmetry. A specific model is discussed in which (1) all three neutrino masses are similar in magnitude and could lie around 1 eV providing the hot component of the dark matter in the Universe, (2) two of these are highly degenerate and their (mass)2 difference could solve the solar neutrino problem through the large angle MSW solution, and (3) the electron neutrino mass may be observable through a Kurie plot as well as through a search of the neutrinoless double β decay.
Neutrino masses in lepton number violating mSUGRA
Kom, Steve C. H.
2008-11-23
In SUSY models which violate R-parity, there exist trilinear lepton number violating (LNV) operators which can lead to neutrino masses. If these operators are defined at the unification scale, the renormalization group flow becomes important and generally leads to one neutrino mass much heavier than the others. We study, in a minimal supergravity (mSUGRA) set-up with two trilinear LNV operators and three charged lepton mixing angles, numerically how these parameters may be arranged to be compatible with neutrino oscillation data, and discuss some phenomenological observations.
Neutrino mass hierarchy and octant determination with atmospheric neutrinos.
Barger, Vernon; Gandhi, Raj; Ghoshal, Pomita; Goswami, Srubabati; Marfatia, Danny; Prakash, Suprabh; Raut, Sushant K; Sankar, S Uma
2012-08-31
The recent discovery by the Daya-Bay and RENO experiments, that θ(13) is nonzero and relatively large, significantly impacts existing experiments and the planning of future facilities. In many scenarios, the nonzero value of θ(13) implies that θ(23) is likely to be different from π/4. Additionally, large detectors will be sensitive to matter effects on the oscillations of atmospheric neutrinos, making it possible to determine the neutrino mass hierarchy and the octant of θ(23). We show that a 50 kT magnetized liquid argon neutrino detector can ascertain the mass hierarchy with a significance larger than 4σ with moderate exposure times, and the octant at the level of 2-3σ with greater exposure.
Extended Higgs sectors in radiative neutrino models
NASA Astrophysics Data System (ADS)
Antipin, Oleg; Čuljak, Petar; Kumerički, Krešimir; Picek, Ivica
2017-05-01
Testable Higgs partners may be sought within the extensions of the SM Higgs sector aimed at generating neutrino masses at the loop level. We study a viability of extended Higgs sectors for two selected models of radiative neutrino masses: a one-loop mass model, providing the Higgs partner within a real triplet scalar representation, and a three-loop mass model, providing it within its two-Higgs-doublet sector. The Higgs sector in the one-loop model may remain stable and perturbative up to the Planck scale, whereas the three-loop model calls for a UV completion around 106 GeV. Additional vector-like lepton and exotic scalar fields, which are required to close one- and three-loop neutrino-mass diagrams, play a decisive role for the testability of the respective models. We constrain the parameter space of these models using LHC bounds on diboson resonances.
McKeown, R. D.
2010-08-04
Recent studies of neutrino oscillations have established the existence of finite neutrino masses and mixing between generations of neutrinos. The combined results from studies of atmospheric neutrinos, solar neutrinos, reactor antineutrinos and neutrinos produced at accelerators paint an intriguing picture that clearly requires modification of the standard model of particle physics. These results also provide clear motivation for future neutrino oscillation experiments as well as searches for direct neutrino mass and nuclear double-beta decay. I will discuss the program of new neutrino oscillation experiments aimed at completing our knowledge of the neutrino mixing matrix.
Neutrino masses from a pseudo-Dirac bino
Coloma, Pilar; Ipek, Seyda
2016-09-09
We show that, in U(1)_{R}-symmetric supersymmetric models, the bino and its Dirac partner (the singlino) can play the role of right-handed neutrinos and generate the neutrino masses and mixing, without the need for traditional bilinear or trilinear R-parity violating operators. The two particles form a pseudo-Dirac pair, the “bi νo.” An inverse seesaw texture is generated for the neutrino-biνo sector, and the lightest neutrino is predicted to be massless. Lastly, unlike in most models with heavy right-handed neutrinos, the bi νo can be sizably produced at the LHC through its interactions with colored particles, while respecting low energy constraints from neutrinoless double-beta decay and charged lepton flavor violation.
Neutrino masses from a pseudo-Dirac bino
Coloma, Pilar; Ipek, Seyda
2016-09-09
We show that, in U(1)_{R}-symmetric supersymmetric models, the bino and its Dirac partner (the singlino) can play the role of right-handed neutrinos and generate the neutrino masses and mixing, without the need for traditional bilinear or trilinear R-parity violating operators. The two particles form a pseudo-Dirac pair, the “bi νo.” An inverse seesaw texture is generated for the neutrino-biνo sector, and the lightest neutrino is predicted to be massless. Lastly, unlike in most models with heavy right-handed neutrinos, the bi νo can be sizably produced at the LHC through its interactions with colored particles, while respecting low energy constraints from neutrinoless double-beta decay and charged lepton flavor violation.
Neutrino masses from a pseudo-Dirac bino
Coloma, Pilar; Ipek, Seyda
2016-09-09
We show that, in U(1)R-symmetric supersymmetric models, the bino and its Dirac partner (the singlino) can play the role of right-handed neutrinos and generate the neutrino masses and mixing, without the need for traditional bilinear or trilinear R-parity violating operators. The two particles form a pseudo-Dirac pair, the “bi νo.” An inverse seesaw texture is generated for the neutrino-biνo sector, and the lightest neutrino is predicted to be massless. Lastly, unlike in most models with heavy right-handed neutrinos, the bi νo can be sizably produced at the LHC through its interactions with colored particles, while respecting low energy constraints frommore » neutrinoless double-beta decay and charged lepton flavor violation.« less
Neutrino Masses from a Pseudo-Dirac Bino
NASA Astrophysics Data System (ADS)
Coloma, Pilar; Ipek, Seyda
2016-09-01
We show that, in U (1 )R -symmetric supersymmetric models, the bino and its Dirac partner (the singlino) can play the role of right-handed neutrinos and generate the neutrino masses and mixing, without the need for traditional bilinear or trilinear R -parity violating operators. The two particles form a pseudo-Dirac pair, the "bi ν o ." An inverse seesaw texture is generated for the neutrino-bi ν o sector, and the lightest neutrino is predicted to be massless. Unlike in most models with heavy right-handed neutrinos, the bi ν o can be sizably produced at the LHC through its interactions with colored particles, while respecting low energy constraints from neutrinoless double-beta decay and charged lepton flavor violation.
Neutrino Masses from a Pseudo-Dirac Bino.
Coloma, Pilar; Ipek, Seyda
2016-09-09
We show that, in U(1)_{R}-symmetric supersymmetric models, the bino and its Dirac partner (the singlino) can play the role of right-handed neutrinos and generate the neutrino masses and mixing, without the need for traditional bilinear or trilinear R-parity violating operators. The two particles form a pseudo-Dirac pair, the "biνo." An inverse seesaw texture is generated for the neutrino-biνo sector, and the lightest neutrino is predicted to be massless. Unlike in most models with heavy right-handed neutrinos, the biνo can be sizably produced at the LHC through its interactions with colored particles, while respecting low energy constraints from neutrinoless double-beta decay and charged lepton flavor violation.
Hernandez-Galeana, Albino
2007-11-01
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){sub L} Higgs triplets. All the resulting mass matrices in the model, for the u, d, and e fermion charged sectors, the neutrinos and the exotic scalar particles, are diagonalized in exact analytical form. Quantitative analysis shows that this model is successful to accommodate the hierarchical spectrum of masses and mixing in the quark sector as well as the charged lepton masses. The lepton mixing matrix, V{sub PMNS}, is written completely in terms of the neutrino masses m{sub 1}, m{sub 2}, and m{sub 3}. Large lepton mixing for {theta}{sub 12} and {theta}{sub 23} is predicted in the range of values 0.7 < or approx. sin{sup 2}2{theta}{sub 12} < or approx. 0.7772 and 0.87 < or approx. sin{sup 2}2{theta}{sub 23} < or approx. 0.9023 by using 0.033 < or approx. s{sub 13}{sup 2} < or approx. 0.04. These values for lepton mixing are consistent with 3{sigma} allowed ranges provided by recent global analysis of neutrino data oscillation. From {delta}m{sub sol}{sup 2} bounds, neutrino masses are predicted in the range of values m{sub 1}{approx_equal}(1.706-2.494)x10{sup -3} eV, m{sub 2}{approx_equal}(6.675-12.56)x10{sup -3} eV, and m{sub 3}{approx_equal}(1.215-2.188)x10{sup -2} eV, respectively. The above allowed lepton mixing leads to the quark-lepton complementary relations {theta}{sub 12}{sup CKM}+{theta}{sub 12}{sup PMNS}{approx_equal}41.543 deg. -44.066 deg. and {theta}{sub 23}{sup CKM}+{theta}{sub 23}{sup PMNS}{approx_equal}36.835 deg. -38.295 deg. The new exotic scalar particles induce flavor changing neutral currents and contribute to lepton flavor violating processes such as E{yields}e{sub 1}e
Lepton mass hierarchy and neutrino oscillations
NASA Astrophysics Data System (ADS)
Fritzsch, Harald; Zhi-Zhong, Xing
1996-02-01
Starting from the symmetry of lepton flavor democracy, we propose and discuss a simple pattern for the mass generation and flavor mixing of the charged leptons and neutrinos. The three neutrino masses are nearly degenerate, and the flavor mixing angles can be calculated. The observed deficit of solar and atmospheric neutrinos can be interpreted as a consequence of the near degeneracy and large oscillations of νe, νμ and ντ in the vacuum. Our ansatz can also accommodate the cosmological requirement for hot dark matter and the current data on neutrinoless ββ-decay.
Higgs mass from neutrino-messenger mixing
NASA Astrophysics Data System (ADS)
Byakti, Pritibhajan; Khosa, Charanjit K.; Mummidi, V. S.; Vempati, Sudhir K.
2017-03-01
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 [1, 2] 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 9 of them can lead to Higgs mass within the observed value without raising the sfermion masses significantly. The successful models have stop masses ˜1.5 TeV with small or negligible mixing and yet a light CP even Higgs at 125 GeV.
A model for pseudo-Dirac neutrinos: leptogenesis and ultra-high energy neutrinos
NASA Astrophysics Data System (ADS)
Ahn, Y. H.; Kang, Sin Kyu; Kim, C. S.
2016-10-01
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. We also discuss future prospect to observe the effects of the pseudo-Dirac property of neutrinos at high energy neutrino experiments.
Minimal supergravity scalar neutrino dark matter and inverse seesaw neutrino masses.
Arina, C; Bazzocchi, F; Fornengo, N; Romao, J C; Valle, J W F
2008-10-17
We show that within the inverse seesaw mechanism for generating neutrino masses, minimal supergravity naturally provides the scalar neutrino as the lightest superparticle. We also demonstrate that such schemes naturally reconcile the small neutrino masses with the correct relic scalar neutrino dark matter abundance and accessible direct detection rates in nuclear recoil experiments. This way, inverse seesaw minimal supergravity offers a common solution to the generation of the neutrino mass and to the origin of dark matter.
Doublet-triplet dark matter with neutrino masses
NASA Astrophysics Data System (ADS)
Betancur, Amalia; Longas, Robinson; Zapata, Oscar
2017-08-01
We consider a dark matter (DM) model that arises from the interplay of two renormalizable dark matter models, namely, the doublet-triplet fermion model and the doublet-triplet scalar model. Despite being excellent exponents of the weakly interacting massive particle paradigm, the physics related to DM in each of these models fails at the same time to account for neutrino masses. It turns out that from the combination of these two models it is possible to generate neutrino masses at one-loop level in the four topologies that are realizations of the Weinberg operator for neutrino masses at one loop. In this work, we combine both models focusing mostly on fermionic dark matter lying at the electroweak scale. We analyze the impact of the extra charged fields on the Higgs diphoton decay and find that, thanks to the presence of the charged scalars, it is possible to have a viable DM region at the electroweak scale.
Fogli, G.L.; Lisi, E.; Marrone, A.; Palazzo, A.; Melchiorri, A.; Serra, P.; Silk, J.
2004-12-01
In the context of three-flavor neutrino mixing, we present a thorough study of the phenomenological constraints applicable to three observables sensitive to absolute neutrino masses: The effective neutrino mass in Tritium beta-decay (m{sub {beta}}); the effective Majorana neutrino mass in neutrinoless double beta-decay (m{sub {beta}}{sub {beta}}); and the sum of neutrino masses in cosmology ({sigma}). We discuss the correlations among these variables which arise from the combination of all the available neutrino oscillation data, in both normal and inverse neutrino mass hierarchy. We set upper limits on m{sub {beta}} by combining updated results from the Mainz and Troitsk experiments. We also consider the latest results on m{sub {beta}}{sub {beta}} from the Heidelberg-Moscow experiment, both with and without the lower bound claimed by such experiment. We derive upper limits on {sigma} from an updated combination of data from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite and the two degrees Fields (2dF) Galaxy Redshifts Survey, with and without Lyman-{alpha} forest data from the Sloan Digital Sky Survey (SDSS), in models with a nonzero running of the spectral index of primordial inflationary perturbations. The results are discussed in terms of two-dimensional projections of the globally allowed region in the (m{sub {beta}},m{sub {beta}}{sub {beta}},{sigma}) parameter space, which neatly show the relative impact of each data set. In particular, the (in)compatibility between {sigma} and m{sub {beta}}{sub {beta}} constraints is highlighted for various combinations of data. We also briefly discuss how future neutrino data (both oscillatory and nonoscillatory) can further probe the currently allowed regions.
Impacts of dark energy on weighing neutrinos: Mass hierarchies considered
NASA Astrophysics Data System (ADS)
Wang, Sai; Wang, Yi-Fan; Xia, Dong-Mei; Zhang, Xin
2016-10-01
Taking into account the mass splittings between three active neutrinos, we investigate the impacts of dark energy on constraining the total neutrino mass ∑mν by using recent cosmological observations. We consider two typical dark energy models, namely, the w CDM model and the holographic dark energy (HDE) model, which both have an additional free parameter compared with the Λ CDM model. We employ the Planck 2015 data of CMB temperature and polarization anisotropies, combined with low-redshift measurements on BAO distance scales, type Ia supernovae, the Hubble constant, and Planck lensing. Compared to the Λ CDM model, our study shows that the upper limit on ∑mν becomes much looser in the w CDM model but much tighter in the HDE model. In the HDE model, we obtain the 95% confidence level upper limit ∑mν<0.105 eV for three degenerate neutrinos. This might be the most stringent constraint on ∑mν by far, and it is on the verge of diagnosing the neutrino mass hierarchies in the HDE model. However, the difference of χ2 is still not significant enough to distinguish the neutrino mass hierarchies, even though the minimal χ2 of the normal hierarchy is slightly smaller than that of the inverted hierarchy.
Observables sensitive to absolute neutrino masses. II
Fogli, G. L.; Marrone, A.; Rotunno, A. M.; Lisi, E.; Melchiorri, A.; Palazzo, A.; Silk, J.; Slosar, A.
2008-08-01
In this followup to Phys. Rev. D 75, 053001 (2007) , we report updated constraints on neutrino mass-mixing parameters, in light of recent neutrino oscillation data (KamLAND, SNO, and MINOS) and cosmological observations (WMAP 5-year and other data). We discuss their interplay with the final 0{nu}2{beta} decay results in {sup 76}Ge claimed by part of the Heidelberg-Moscow Collaboration, using recent evaluations of the corresponding nuclear matrix elements, and their uncertainties. We also comment on the 0{nu}2{beta} limits in {sup 130}Te recently set by Cuoricino and on prospective limits or signals from the Karlsruhe tritium neutrino experiment.
Neutrino masses and ordering via multimessenger astronomy
NASA Astrophysics Data System (ADS)
Langæble, Kasper; Meroni, Aurora; Sannino, Francesco
2016-09-01
We define the theoretical framework and deduce the conditions under which multimessenger astronomy can provide useful information about neutrino masses and their ordering. The framework uses time differences between the arrival of neutrinos and the other light messenger, i.e. the graviton, emitted in astrophysical catastrophes. We also provide a preliminary feasibility study elucidating the experimental reach and challenges for planned neutrino detectors such as Hyper-Kamiokande as well as future several-megaton detectors. This study shows that future experiments can be useful in independently testing the cosmological bounds on absolute neutrino masses. Concretely, the success of such measurements depends crucially on the available rate of astrophysical events and further requires development of high resolution timing besides the need for megaton-size detectors.
Measurement of neutrino masses from relative velocities.
Zhu, Hong-Ming; Pen, Ue-Li; Chen, Xuelei; Inman, Derek; Yu, Yu
2014-09-26
We present a new technique to measure neutrino masses using their flow field relative to dark matter. Present day streaming motions of neutrinos relative to dark matter and baryons are several hundred km/s, comparable with their thermal velocity dispersion. This results in a unique dipole anisotropic distortion of the matter-neutrino cross power spectrum, which is observable through the dipole distortion in the cross correlation of different galaxy populations. Such a dipole vanishes if not for this relative velocity and so it is a clean signature for neutrino mass. We estimate the size of this effect and find that current and future galaxy surveys may be sensitive to these signature distortions.
Comments on the determination of the neutrino mass ordering in reactor neutrino experiments
NASA Astrophysics Data System (ADS)
Bilenky, S. M.
2017-05-01
We consider the problem of determination of the neutrino mass ordering via precise study of the vacuum neutrino oscillations in the JUNO and other future medium baseline reactor neutrino experiments. We are proposing to resolve neutrino mass ordering by determination of the neutrino oscillation parameters from analysis of the data of the reactor experiments and comparison them with the oscillation parameters obtained from analysis of the solar and KamLAND experiments.
Neutrino masses and mixings in non-factorizable geometry
Grossman, Y.
2000-01-07
The authors study bulk fermion fields in the localized gravity model with non-factorizable metric recently proposed by Randall and Sundrum, and Gogberashvili. In addition to a tower of weak-scale Kaluza-Klein states the authors find a zero mode for any value of the fundamental fermion mass. If the fermion mass is larger than half the curvature of the compact dimension, the zero mode can be localized on the ``hidden'' 3-brane in the Randall-Sundrum model. Identifying this mode with a right-handed neutrino provides a new way for obtaining small Dirac neutrino masses without invoking a see-saw mechanism. Cancellation of the parity anomaly requires introducing an even number of bulk fermions. This naturally leads to a strong hierarchy of neutrino masses and generically large mixing angles.
Zero minors of the neutrino mass matrix
Lashin, E. I.; Chamoun, N.
2008-10-01
We examine the possibility that a certain class of neutrino mass matrices, namely, those with two independent vanishing minors in the flavor basis, regardless of being invertible or not, is sufficient to describe current data. We compute generic formulas for the ratios of the neutrino masses and for the Majorana phases. We find that seven textures with two vanishing minors can accommodate the experimental data. We present an estimate of the mass matrix for these patterns. All of the possible textures can be dynamically generated through the seesaw mechanism augmented with a discrete Abelian symmetry.
Constraining bilinear R-parity violation from neutrino masses
NASA Astrophysics Data System (ADS)
Góźdź, Marek; Kamiński, Wiesław A.
2008-10-01
We confront the R-parity violating minimal supersymmetric standard model with the neutrino oscillation data. Investigating the 1-loop particle-sparticle diagrams with additional bilinear insertions on the external neutrino lines we construct the relevant contributions to the neutrino mass matrix. A comparison of the so-obtained matrices with the experimental ones assuming normal or inverted hierarchy and taking into account possible CP-violating phases allows to set constraints on the values of the bilinear coupling constants. A similar calculation is presented with the input from the Heidelberg-Moscow neutrinoless double beta decay experiment. We base our analysis on the renormalization group evolution of the minimal supersymmetric standard model parameters which are unified at the grand unified theory scale. Using the obtained bounds we calculate the contributions to the Majorana neutrino transition magnetic moments.
Small Neutrino Masses from Supersymmetry Breaking
Arkani-Hamed, Nima; Hall, Lawrence; Murayama, Hitoshi; Smith, David; Weiner, Neal
2000-06-27
An alternative to the conventional see-saw mechanism is proposed to explain the origin of small neutrino masses in supersymmetric theories. The masses and couplings of the right-handed neutrino field are suppressed by supersymmetry breaking, in a way similar to the suppression of the Higgs doublet mass, $\\mu$. New mechanisms for light Majorana, Dirac and sterile neutrinos arise, depending on the degree of suppression. Superpartner phenomenology is greatly altered by the presence of weak scale right-handed sneutrinos, which may have a coupling to a Higgs boson and a left-handed sneutrino. The sneutrino spectrum and couplings are quite unlike the conventional case - the lightest sneutrino can be the dark matter and predictions are given for event rates at upcoming halo dark matter direct detection experiments. Higgs decays and search strategies are changed. Copious Higgs production at hadron colliders can result from cascade decays of squarks and gluinos.
The Higgs seesaw induced neutrino masses and dark matter
Cai, Yi; Chao, Wei
2015-08-12
In this study we propose a possible explanation of the active neutrino Majorana masses with the TeV scale new physics which also provide a dark matter candidate. We extend the Standard Model (SM) with a local U(1)' symmetry and introduce a seesaw relation for the vacuum expectation values (VEVs) of the exotic scalar singlets, which break the U(1)' spontaneously. The larger VEV is responsible for generating the Dirac mass term of the heavy neutrinos, while the smaller for the Majorana mass term. As a result active neutrino masses are generated via the modified inverse seesaw mechanism. The lightest of themore » new fermion singlets, which are introduced to cancel the U(1)' anomalies, can be a stable particle with ultra flavor symmetry and thus a plausible dark matter candidate. We explore the parameter space with constraints from the dark matter relic abundance and dark matter direct detection.« less
Probing neutrino masses with CMB lensing extraction
Lesgourgues, Julien; Perotto, Laurence; Pastor, Sergio; Piat, Michel
2006-02-15
We evaluate the ability of future cosmic microwave background (CMB) experiments to measure the power spectrum of large scale structure using quadratic estimators of the weak lensing deflection field. We calculate the sensitivity of upcoming CMB experiments such as BICEP, QUaD, BRAIN, ClOVER and Planck to the nonzero total neutrino mass M{sub {nu}} indicated by current neutrino oscillation data. We find that these experiments greatly benefit from lensing extraction techniques, improving their one-sigma sensitivity to M{sub {nu}} by a factor of order four. The combination of data from Planck and the SAMPAN mini-satellite project would lead to {sigma}(M{sub {nu}}){approx}0.1 eV, while a value as small as {sigma}(M{sub {nu}}){approx}0.035 eV is within the reach of a space mission based on bolometers with a passively cooled 3-4 m aperture telescope, representative of the most ambitious projects currently under investigation. We show that our results are robust not only considering possible difficulties in subtracting astrophysical foregrounds from the primary CMB signal but also when the minimal cosmological model ({lambda} Mixed Dark Matter) is generalized in order to include a possible scalar tilt running, a constant equation-of-state parameter for the dark energy and/or extra relativistic degrees of freedom.
Improvement of cosmological neutrino mass bounds
NASA Astrophysics Data System (ADS)
Giusarma, Elena; Gerbino, Martina; Mena, Olga; Vagnozzi, Sunny; Ho, Shirley; Freese, Katherine
2016-10-01
The most recent measurements of the temperature and low-multipole polarization anisotropies of the cosmic microwave background from the Planck satellite, when combined with galaxy clustering data from the Baryon Oscillation Spectroscopic Survey in the form of the full shape of the power spectrum, and with baryon acoustic oscillation measurements, provide a 95% confidence level (C.L.) upper bound on the sum of the three active neutrinos ∑mν<0.183 eV , among the tightest neutrino mass bounds in the literature, to date, when the same data sets are taken into account. This very same data combination is able to set, at ˜70 % C.L., an upper limit on ∑mν of 0.0968 eV, a value that approximately corresponds to the minimal mass expected in the inverted neutrino mass hierarchy scenario. If high-multipole polarization data from Planck is also considered, the 95% C.L. upper bound is tightened to ∑mν<0.176 eV . Further improvements are obtained by considering recent measurements of the Hubble parameter. These limits are obtained assuming a specific nondegenerate neutrino mass spectrum; they slightly worsen when considering other degenerate neutrino mass schemes. Low-redshift quantities, such as the Hubble constant or the reionization optical depth, play a very important role when setting the neutrino mass constraints. We also comment on the eventual shifts in the cosmological bounds on ∑mν when possible variations in the former two quantities are addressed.
Peccei, R. D.
1999-10-25
These lectures describe some aspects of the physics of massive neutrinos. After a brief introduction of neutrinos in the Standard Model, I discuss possible patterns for their masses. In particular, I show how the presence of a large Majorana mass term for the right-handed neutrinos can engender tiny neutrino masses for the observed neutrinos. If neutrinos have mass, different flavors of neutrinos can oscillate into one another. To analyze this phenomena, I develop the relevant formalism for neutrino oscillations, both in vacuum and in matter. After reviewing the existing (negative) evidence for neutrino masses coming from direct searches, I discuss evidence for, and hints of, neutrino oscillations in the atmosphere, the sun, and at accelerators. Some of the theoretical implications of these results are emphasized. I close these lectures by briefly outlining future experiments which will shed further light on atmospheric, accelerator and solar neutrino oscillations. A pedagogical discussion of Dirac and Majorana masses is contained in an appendix.
NASA Astrophysics Data System (ADS)
Hirsch, M.; Díaz, M. A.; Porod, W.; Romão, J. C.; Valle, J. W. F.
2000-12-01
The simplest unified extension of the minimal supersymmetric standard model with bilinear R-parity violation naturally predicts a hierarchical neutrino mass spectrum, in which one neutrino acquires mass by mixing with neutralinos, while the other two get mass radiatively. We have performed a full one-loop calculation of the neutralino-neutrino mass matrix in the bilinear R/p minimal supersymmetric standard model, taking special care to achieve a manifestly gauge invariant calculation. Moreover we have performed the renormalization of the heaviest neutrino, needed in order to get meaningful results. The atmospheric mass scale and maximal mixing angle arise from tree-level physics, while solar neutrino scale and oscillations follow from calculable one-loop corrections. If universal supergravity assumptions are made on the soft-supersymmetry breaking terms then the atmospheric scale is calculable as a function of a single R/p violating parameter by the renormalization group evolution due to the nonzero bottom quark Yukawa coupling. The solar neutrino problem must be accounted for by the small mixing angle Mikheyev-Smirnov-Wolfenstein (MSW) solution. If these assumptions are relaxed then one can implement large mixing angle solutions. The theory predicts the lightest supersymmetic particle decay to be observable at high-energy colliders, despite the smallness of neutrino masses indicated by experiment. This provides an independent way to test this solution of the atmospheric and solar neutrino anomalies.
Cosmology in Mirror Twin Higgs and neutrino masses
NASA Astrophysics Data System (ADS)
Chacko, Zackaria; Craig, Nathaniel; Fox, Patrick J.; Harnik, Roni
2017-07-01
We explore a simple solution to the cosmological challenges of the original Mirror Twin Higgs (MTH) model that leads to interesting implications for experiment. We consider theories in which both the standard model and mirror neutrinos acquire masses through the familiar seesaw mechanism, but with a low right-handed neutrino mass scale of order a few GeV. In these νMTH models, the right-handed neutrinos leave the thermal bath while still relativistic. As the universe expands, these particles eventually become nonrelativistic, and come to dominate the energy density of the universe before decaying. Decays to standard model states are preferred, with the result that the visible sector is left at a higher temperature than the twin sector. Consequently the contribution of the twin sector to the radiation density in the early universe is suppressed, allowing the current bounds on this scenario to be satisfied. However, the energy density in twin radiation remains large enough to be discovered in future cosmic microwave background experiments. In addition, the twin neutrinos are significantly heavier than their standard model counterparts, resulting in a sizable contribution to the overall mass density in neutrinos that can be detected in upcoming experiments designed to probe the large scale structure of the universe.
NASA Astrophysics Data System (ADS)
Bergström, L.; Hulth, P. O.; Botner, O.; Carlson, P.; Ohlsson, T.
2006-03-01
J. N. Bahcall (1934-2005) -- Preface -- List of participants -- Committees -- Nobel symposium on neutrino physics - program -- The history of neutrino oscillations / S. M. Bilenky -- Super-Kamiokande results on neutrino oscillations / Y. Suzuki -- Sudbury neutrino observatory results / A. B. McDonald -- Results from KamLAND reactor neutrino detection / A. Suzuki -- New opportunities for surprise / J. Conrad -- Solar models and solar neutrinos / J. N. Bahcall -- Atmospheric neutrino fluxes / T. K. Gaisser -- The MSW effect and matter effects in neutrino oscillations / A. Yu. Smirnov -- Three-flavour effects and CP- and T-violation in neutrino oscillations / E. Kh. Akhmedov -- Global analysis of neutrino data / M. C. Gonzalez-Garcia -- Future precision neutrino oscillation experiments and theoretical implications / M. Lindner -- Experimental prospects of neutrinoless double beta decay / E. Fiorini -- Theoretical prospects of neutrinoless double beta decay / S. T. Petcov -- Supernova neutrino oscillations / G. G. Raffelt -- High-energy neutrino astronomy / F. Halzen -- Neutrino astrophysics in the cold: Amanda, Baikal and IceCube / C. Spiering -- Status of radio and acoustic detection of ultra-high energy cosmic neutrinos and a proposal on reporting results / D. Saltzberg -- Detection of neutrino-induced air showers / A. A. Watson -- Prospect for relic neutrino searches / G. B. Gelmini -- Leptogenesis in the early universe / T. Yanagida -- Neutrinos and big bang nucleosynthesis / G. Steigman -- Extra galactic sources of high energy neutrinos / E. Waxman -- Cosmological neutrino bounds for non-cosmologists / M. Tegmark -- Neutrino intrinsic properties: the neutrino-antineutrino relation / B. Kayser -- NuTeV and neutrino properties / M. H. Shaevitz -- Absolute masses of neutrinos - experimental results and future possibilities / C. Weinheimer -- Flavor theories and neutrino masses / P. Ramond -- Neutrino mass models and leptogenesis / S. F. King -- Neutrino mass and
Explaining solar neutrinos with heavy Higgs masses in partial split supersymmetry
Diaz, Marco Aurelio; Garay, Francisca; Koch, Benjamin
2009-12-01
Partial Split Supersymmetry with violation of R-parity as a model for neutrino masses is explored. It is shown that at the one-loop level the model can give predictions that are in agreement with all present experimental values for the neutrino sector. An analytical result is that the small solar neutrino mass difference can be naturally explained in the decoupling limit for the heavy Higgs mass eigenstates.
Challenges Confronting Superluminal Neutrino Models
NASA Astrophysics Data System (ADS)
Evslin, Jarah
2012-12-01
This talk opens the CosPA2011 session on OPERA's superluminal neutrino claim. I summarize relevant observations and constraints from OPERA, MINOS, ICARUS, KamLAND, IceCube and LEP as well as observations of SN1987A. I selectively review some models of neutrino superluminality which have been proposed since OPERA's announcement, focusing on a neutrino dark energy model. Powerful theoretical constraints on these models arise from Cohen-Glashow bremsstrahlung and from phase space requirements for the initial neutrino production. I discuss these constraints and how they might be evaded in models in which the maximum velocities of both neutrinos and charged leptons are equal but only superluminal inside of a dense medium.
Gu, Pei-Hong
2014-12-01
We propose an SO(10) × SO(10)' model to simultaneously realize a seesaw for Dirac neutrino masses and a leptogenesis for ordinary and dark matter-antimatter asymmetries. A (16 × 1-bar 6-bar '){sub H} scalar crossing the SO(10) and SO(10)' sectors plays an essential role in this seesaw-leptogenesis scenario. As a result of lepton number conservation, the lightest dark nucleon as the dark matter particle should have a determined mass around 15 GeV to explain the comparable fractions of ordinary and dark matter in the present universe. The (16 × 1-bar 6-bar '){sub H} scalar also mediates a U(1){sub em} × U(1)'{sub em} kinetic mixing after the ordinary and dark left-right symmetry breaking so that we can expect a dark nucleon scattering in direct detection experiments and/or a dark nucleon decay in indirect detection experiments. Furthermore, we can impose a softly broken mirror symmetry to simplify the parameter choice.
Shedding light on neutrino masses with dark forces
NASA Astrophysics Data System (ADS)
Batell, Brian; Pospelov, Maxim; Shuve, Brian
2016-08-01
Heavy right-handed neutrinos, N , provide the simplest explanation for the origin of light neutrino masses and mixings. If M N is at or below the weak scale, direct experimental discovery of these states is possible at accelerator experiments such as the LHC or new dedicated beam dump experiments; in these experiments, N decays after traversing a macroscopic distance from the collision point. The experimental sensitivity to right-handed neutrinos is significantly enhanced if there is a new "dark" gauge force connecting them to the Standard Model (SM), and detection of N can be the primary discovery mode for the new dark force itself. We take the well-motivated example of a B - L gauge symmetry and analyze the sensitivity to displaced decays of N produced via the new gauge interaction in two experiments: the LHC and the proposed SHiP beam dump experiment. In the most favorable case in which the mediator can be produced on-shell and decays to right handed neutrinos ( pp → X + V B- L → X + N N ), the sensitivity reach is controlled by the square of the B - L gauge coupling. We demonstrate that these experiments could access neutrino parameters responsible for the observed SM neutrino masses and mixings in the most straightforward implementation of the see-saw mechanism.
Shedding light on neutrino masses with dark forces
Batell, Brian; Pospelov, Maxim; Shuve, Brian
2016-08-08
Heavy right-handed neutrinos, N , provide the simplest explanation for the origin of light neutrino masses and mixings. If MN is at or below the weak scale, direct experimental discovery of these states is possible at accelerator experiments such as the LHC or new dedicated beam dump experiments; in these experiments, N decays after traversing a macroscopic distance from the collision point. The experimental sensitivity to right-handed neutrinos is significantly enhanced if there is a new “dark” gauge force connecting them to the Standard Model (SM), and detection of N can be the primary discovery mode for the new darkmore » force itself. We take the well-motivated example of a B – L gauge symmetry and analyze the sensitivity to displaced decays of N produced via the new gauge interaction in two experiments: the LHC and the proposed SHiP beam dump experiment. In the most favorable case in which the mediator can be produced on-shell and decays to right handed neutrinos (pp → X + VB–L → X + N N ), the sensitivity reach is controlled by the square of the B – L gauge coupling. Here, we demonstrate that these experiments could access neutrino parameters responsible for the observed SM neutrino masses and mixings in the most straightforward implementation of the see-saw mechanism.« less
Shedding light on neutrino masses with dark forces
Batell, Brian; Pospelov, Maxim; Shuve, Brian
2016-08-08
Heavy right-handed neutrinos, N , provide the simplest explanation for the origin of light neutrino masses and mixings. If M_{N} is at or below the weak scale, direct experimental discovery of these states is possible at accelerator experiments such as the LHC or new dedicated beam dump experiments; in these experiments, N decays after traversing a macroscopic distance from the collision point. The experimental sensitivity to right-handed neutrinos is significantly enhanced if there is a new “dark” gauge force connecting them to the Standard Model (SM), and detection of N can be the primary discovery mode for the new dark force itself. We take the well-motivated example of a B – L gauge symmetry and analyze the sensitivity to displaced decays of N produced via the new gauge interaction in two experiments: the LHC and the proposed SHiP beam dump experiment. In the most favorable case in which the mediator can be produced on-shell and decays to right handed neutrinos (pp → X + V_{B–L} → X + N N ), the sensitivity reach is controlled by the square of the B – L gauge coupling. Here, we demonstrate that these experiments could access neutrino parameters responsible for the observed SM neutrino masses and mixings in the most straightforward implementation of the see-saw mechanism.
Neutrino mass hierarchy determination using reactor antineutrinos
NASA Astrophysics Data System (ADS)
Ghoshal, Pomita; Petcov, S. T.
2011-03-01
Building on earlier studies, we investigate the possibility to determine the type of neutrino mass spectrum (i.e., "the neutrino mass hierarchy") in a high statistics reactor {bar{ν }_e} experiment with a relatively large KamLAND-like detector and an optimal baseline of 60 Km. We analyze systematically the Fourier Sine and Cosine Transforms (FST and FCT) of simulated reactor antineutrino data with reference to their specific mass hierarchy-dependent features discussed earlier in the literature. We perform also a binned χ 2 analysis of the sensitivity of simulated reactor {bar{ν }_e} event spectrum data to the neutrino mass hierarchy, and determine, in particular, the characteristics of the detector and the experiment (energy resolution, visible energy threshold, exposure, systematic errors, binning of data, etc.), which would allow us to get significant information on, or even determine, the type of the neutrino mass spectrum. We find that if sin2 2 θ 13 is sufficiently large, sin2 2 θ 13 ≳ 0 .02, the requirements on the set-up of interest are very challenging, but not impossible to realize.
Towards a cosmological neutrino mass detection
NASA Astrophysics Data System (ADS)
Allison, R.; Caucal, P.; Calabrese, E.; Dunkley, J.; Louis, T.
2015-12-01
Future cosmological measurements should enable the sum of neutrino masses to be determined indirectly through their effects on the expansion rate of the Universe and the clustering of matter. We consider prospects for the gravitationally lensed cosmic microwave background (CMB) anisotropies and baryon acoustic oscillations (BAOs) in the galaxy distribution, examining how the projected uncertainty of ≈15 meV on the neutrino mass sum (a 4 σ detection of the minimal mass) might be reached over the next decade. The current 1 σ uncertainty of ≈103 meV (Planck-2015 +BAO -15 ) will be improved by upcoming "Stage-3" (S3) CMB experiments (S 3 +BAO -15 : 44 meV ), then upcoming BAO measurements (S 3 +DESI : 22 meV ), and planned next-generation "Stage 4" (S4) CMB experiments (S 4 +DESI : 15 - 19 meV , depending on angular range). An improved optical depth measurement is important: the projected neutrino mass uncertainty increases to 26 meV if S4 is limited to ℓ>20 and combined with current large-scale polarization data. Looking beyond Λ CDM , including curvature uncertainty increases the forecast mass error by ≈50 % for S 4 +DESI , and more than doubles the error with a two-parameter dark-energy equation of state. Complementary low-redshift probes including galaxy lensing will play a role in distinguishing between massive neutrinos and a departure from a w =-1 , flat geometry.
Universal Extra Dimension models with right-handed neutrinos
Matsumoto, Shigeki; Sato, Joe; Yamanaka, Masato; Senami, Masato
2008-04-21
Relic abundance of dark matter is investigated in the framework of universal extra dimension (UED) models with right-handed neutrinos. These models are free from the KK graviton problem in the minimal UED model. The first KK particle of the right-handed neutrino is a dark matter candidate in this framework. When ordinary neutrino masses are large enough such as the degenerate mass spectrum case, the dark matter relic abundance can increase significantly. The scale of the extra dimension consistent with cosmological observations can be 500 GeV in the minimal setup of UED models with right-handed 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.
Neutrino Mass Seesaw Version 3: Recent Developments
Ma, Ernest
2009-04-20
The origin of neutrino mass is usually attributed to a seesaw mechanism, either through a heavy Majorana fermion singlet (version 1) or a heavy scalar triplet (version 2). Recently, the idea of using a heavy Majorana fermion triplet (version 3) has gained some attention. This is a review of the basic idea involved, its U(1) gauge extension, and some recent developments.
Late Time Neutrino Masses, the LSND Experiment and the Cosmic Microwave Background
Chacko, Z.; Hall, Lawrence J.; Oliver, Steven J.; Perelstein, Maxim
2004-05-07
Models with low-scale breaking of global symmetries in the neutrino sector provide an alternative to the seesaw mechanism for understanding why neutrinos are light. Such models can easily incorporate light sterile neutrinos required by the LSND experiment. Furthermore, the constraints on the sterile neutrino properties from nucleosynthesis and large scale structure can be removed due to the non-conventional cosmological evolution of neutrino masses and densities. We present explicit, fully realistic supersymmetric models, and discuss the characteristic signatures predicted in the angular distributions of the cosmic microwave background.
Unique forbidden beta decays and neutrino mass
Dvornický, Rastislav; Šimkovic, Fedor
2015-10-28
The measurement of the electron energy spectrum in single β decays close to the endpoint provides a direct determination of the neutrino masses. The most sensitive experiments use β decays with low Q value, e.g. KATRIN (tritium) and MARE (rhenium). We present the theoretical spectral shape of electrons emitted in the first, second, and fourth unique forbidden β decays. Our findings show that the Kurie functions for these unique forbidden β transitions are linear in the limit of massless neutrinos like the Kurie function of the allowed β decay of tritium.
Measuring neutrino masses with a future galaxy survey
Hamann, Jan; Hannestad, Steen; Wong, Yvonne Y.Y. E-mail: sth@phys.au.dk
2012-11-01
We perform a detailed forecast on how well a EUCLID-like photometric galaxy and cosmic shear survey will be able to constrain the absolute neutrino mass scale. Adopting conservative assumptions about the survey specifications and assuming complete ignorance of the galaxy bias, we estimate that the minimum mass sum of Σm{sub ν} ≅ 0.06 eV in the normal hierarchy can be detected at 1.5σ to 2.5σ significance, depending on the model complexity, using a combination of galaxy and cosmic shear power spectrum measurements in conjunction with CMB temperature and polarisation observations from PLANCK. With better knowledge of the galaxy bias, the significance of the detection could potentially reach 5.4σ. Interestingly, neither PLANCK+shear nor PLANCK+galaxy alone can achieve this level of sensitivity; it is the combined effect of galaxy and cosmic shear power spectrum measurements that breaks the persistent degeneracies between the neutrino mass, the physical matter density, and the Hubble parameter. Notwithstanding this remarkable sensitivity to Σm{sub ν}, EUCLID-like shear and galaxy data will not be sensitive to the exact mass spectrum of the neutrino sector; no significant bias ( < 1σ) in the parameter estimation is induced by fitting inaccurate models of the neutrino mass splittings to the mock data, nor does the goodness-of-fit of these models suffer any significant degradation relative to the true one (Δχ{sub eff}{sup 2} < 1)
Reconstructing SUSY and R-Neutrino Masses in SO(10)
Deppisch, F.; Freitas, A.; Porod, W.; Zerwas, P. M.
2008-11-23
We report on the extrapolation of scalar mass parameters in the lepton sector to reconstruct SO(10) scenarios close to the unification scale. The method is demonstrated for an example in which SO(10) is broken directly to the Standard Model, based on the expected precision from coherent LHC and ILC collider analyses. In addition to the fundamental scalar mass parameters at the unification scale, the mass of the heaviest right-handed neutrino can be estimated in the seesaw scenario.
QLC relation and neutrino mass hierarchy
Ferrandis, Javier; Pakvasa, Sandip
2005-01-27
Latest measurements have revealed that the deviation from a maximal solar mixing angle is approximately the Cabibbo angle, i.e., QLC relation. We argue that it is not plausible that this deviation from maximality, be it a coincidence or not, comes from the charged lepton mixing. Consequently we have calculated the required corrections to the exactly bimaximal neutrino mass matrix ansatz necessary to account for the solar mass difference and the solar mixing angle. We point out that the relative size of these two corrections depends strongly on the hierarchy case under consideration. We find that the inverted hierarchy case with opposite CP parities, which is known to guarantee the RGE stability of the solar mixing angle, offers the most plausible scenario for a high energy origin of a QLC-corrected bimaximal neutrino mass matrix. This possibility may allow us to explain the QLC relation in connection with the origin of the charged fermion mass matrices.
Phenomenological study of extended seesaw model for light sterile neutrino
NASA Astrophysics Data System (ADS)
Nath, Newton; Ghosh, Monojit; Goswami, Srubabati; Gupta, Shivani
2017-03-01
We study the zero textures of the Yukawa matrices in the minimal extended type-I seesaw (MES) model which can give rise to ˜ eV scale sterile neutrinos. In this model, three right handed neutrinos and one extra singlet S are added to generate a light sterile neutrino. The light neutrino mass matrix for the active neutrinos, m ν , depends on the Dirac neutrino mass matrix ( M D ), Majorana neutrino mass matrix ( M R ) and the mass matrix ( M S ) coupling the right handed neutrinos and the singlet. The model predicts one of the light neutrino masses to vanish. We systematically investigate the zero textures in M D and observe that maximum five zeros in M D can lead to viable zero textures in m ν . For this study we consider four different forms for M R (one diagonal and three off diagonal) and two different forms of ( M S ) containing one zero. Remarkably we obtain only two allowed forms of m ν ( m eτ = 0 and m ττ = 0) having inverted hierarchical mass spectrum. We re-analyze the phenomenological implications of these two allowed textures of m ν in the light of recent neutrino oscillation data. In the context of the MES model, we also express the low energy mass matrix, the mass of the sterile neutrino and the active-sterile mixing in terms of the parameters of the allowed Yukawa matrices. The MES model leads to some extra correlations which disallow some of the Yukawa textures obtained earlier, even though they give allowed one-zero forms of m ν . We show that the allowed textures in our study can be realized in a simple way in a model based on MES mechanism with a discrete Abelian flavor symmetry group Z 8 × Z 2.
NASA Astrophysics Data System (ADS)
Dermíšek, Radovan
2004-08-01
We show that both small mixing in the quark sector and large mixing in the lepton sector can be obtained from a simple assumption of universality of Yukawa couplings and the right-handed neutrino Majorana mass matrix in leading order. We discuss conditions under which bilarge mixing in the lepton sector is achieved with a minimal amount of fine-tuning requirements for possible models. From knowledge of the solar and atmospheric mixing angles we determine the allowed values of sin θ13. If embedded into grand unified theories, the third generation Yukawa coupling unification is a generic feature while masses of the first two generations of charged fermions depend on small perturbations. In the neutrino sector, the heavier two neutrinos are model dependent, while the mass of the lightest neutrino in this approach does not depend on perturbations in the leading order. The right-handed neutrino mass scale can be identified with the GUT scale in which case the mass of the lightest neutrino is given as (m2top/MGUT)sin2 θ23 sin2 θ12 in the limit sin θ13≃0. Discussing symmetries we make a connection with hierarchical models and show that the basis independent characteristic of this scenario is a strong dominance of the third generation right-handed neutrino, M1,M2<10-4M3, M3=MGUT.
Generalized mass ordering degeneracy in neutrino oscillation experiments
Coloma, Pilar; Schwetz, Thomas
2016-09-07
Here, we consider the impact of neutral-current (NC) nonstandard neutrino interactions (NSI) on the determination of the neutrino mass ordering. We show that in the 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 θ_{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-1 corrections from NSI to the NC electron neutrino-quark interaction and can be tested in electron neutrino NC scattering experiments.
Generalized mass ordering degeneracy in neutrino oscillation experiments
Coloma, Pilar; Schwetz, Thomas
2016-09-07
Here, we consider the impact of neutral-current (NC) nonstandard neutrino interactions (NSI) on the determination of the neutrino mass ordering. We show that in the 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 θ_{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-1 corrections from NSI to the NC electron neutrino-quark interaction and can be tested in electron neutrino NC scattering experiments.
Generalized mass ordering degeneracy in neutrino oscillation experiments
NASA Astrophysics Data System (ADS)
Coloma, Pilar; Schwetz, Thomas
2016-09-01
We consider the impact of neutral-current (NC) nonstandard neutrino interactions (NSI) on the determination of the neutrino mass ordering. We show that in the 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 θ12 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-1 corrections from NSI to the NC electron neutrino-quark interaction and can be tested in electron neutrino NC scattering experiments.
NASA Astrophysics Data System (ADS)
Schneps, J.; Kafka, T.; Mann, W. A.; Nath, P.
Contents: 1. Neutrino mass. 2. Neutrino oscillations. 3. Double beta decay. 4. Solar neutrinos. 5. Neutrinos from supernovae. 6. Neutrino interactions at accelerators. 7. New detectors for neutrino processes. 8. Neutrino interactions at accelerators II. 9. W, Z, and the standard model. 10. "Fred Reines at 70" Fest. 11. Nucleon decay, the standard model, and beyond. 12. Neutrinos: Earth, atmosphere, Sun, and galaxies. 13. Dark matter and cosmology. 14. Theoretical topics. 15. Future prospects.
One vanishing minor in the neutrino mass matrix
Lashin, E. I.; Chamoun, N.
2009-11-01
We study a specific texture of the neutrino mass matrix, namely the models with one 2x2 subdeterminant equal to zero. We carry out a complete phenomenological analysis with all possible relevant correlations. Every pattern of the six possible ones is found able to accommodate the experimental data, with three cases allowing also for noninvertible mass matrices. We present symmetry realizations for all the models.
Implications of 4 texture zeros mass matrices for neutrino anomalies
NASA Astrophysics Data System (ADS)
Gill, P. S.; Gupta, Manmohan
1998-04-01
Phenomenological 4 texture zeros mass matrices, successful in accommodating the CKM phenomenology, are used to simultaneously explain the three neutrino anomalies: the solar neutrino problem (SNP), the atmospheric neutrino problem (ANP), and the LSND anomaly. When the SNP is resolved through vacuum oscillations, we obtain a solution implying large mixing. In case the SNP is resolved through the MSW mechanism, the neutrino masses follow a ``natural'' hierarchy.
The halo model in a massive neutrino cosmology
Massara, Elena; Villaescusa-Navarro, Francisco; Viel, Matteo E-mail: villaescusa@oats.inaf.it
2014-12-01
We provide a quantitative analysis of the halo model in the context of massive neutrino cosmologies. We discuss all the ingredients necessary to model the non-linear matter and cold dark matter power spectra and compare with the results of N-body simulations that incorporate massive neutrinos. Our neutrino halo model is able to capture the non-linear behavior of matter clustering with a ∼20% accuracy up to very non-linear scales of k = 10 h/Mpc (which would be affected by baryon physics). The largest discrepancies arise in the range k = 0.5 – 1 h/Mpc where the 1-halo and 2-halo terms are comparable and are present also in a massless neutrino cosmology. However, at scales k < 0.2 h/Mpc our neutrino halo model agrees with the results of N-body simulations at the level of 8% for total neutrino masses of < 0.3 eV. We also model the neutrino non-linear density field as a sum of a linear and clustered component and predict the neutrino power spectrum and the cold dark matter-neutrino cross-power spectrum up to k = 1 h/Mpc with ∼30% accuracy. For masses below 0.15 eV the neutrino halo model captures the neutrino induced suppression, casted in terms of matter power ratios between massive and massless scenarios, with a 2% agreement with the results of N-body/neutrino simulations. Finally, we provide a simple application of the halo model: the computation of the clustering of galaxies, in massless and massive neutrinos cosmologies, using a simple Halo Occupation Distribution scheme and our halo model extension.
Neutrino mass hierarchy and stepwise spectral swapping of supernova neutrino flavors.
Duan, Huaiyu; Fuller, George M; Carlson, J; Qian, Yong-Zhong
2007-12-14
We examine a phenomenon recently predicted by numerical simulations of supernova neutrino flavor evolution: the swapping of supernova nu(e) and nu(mu,tau) energy spectra below (above) energy E(C) 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, E(C) decreases as the assumed effective 2x2 vacuum nu(e)<==>nu(mu,tau) mixing angle (approximately theta13) is decreased. In contrast, these calculations indicate that E(C) 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 theta13 is too small to be measured by terrestrial neutrino oscillation experiments.
NASA Astrophysics Data System (ADS)
Fukugita, Masataka; Kaneta, Yuya; Shimizu, Yusuke; Tanimoto, Morimitsu; Yanagida, Tsutomu T.
2017-01-01
The model of neutrino mass matrix with minimal texture is now tightly constrained by experiment so that it can yield a prediction for the phase of CP violation. This phase is predicted to lie in the range δCP = 0.77 π- 1.24 π. If neutrino oscillation experiment would find the CP violation phase outside this range, this means that the minimal-texture neutrino mass matrix, the element of which is all real, fails and the neutrino mass matrix must be complex, i.e., the phase must be present that is responsible for leptogenesis.
Besson, Dave; Cowen, Doug; Selen, Mats; Wiebusch, Christopher
1999-01-01
Neutrinos represent a new “window” to the Universe, spanning a large range of energy. We discuss the science of neutrino astrophysics and focus on two energy regimes. At “lower” energies (≈1 MeV), studies of neutrinos born inside the sun, or produced in interactions of cosmic rays with the atmosphere, have allowed the first incontrovertible evidence that neutrinos have mass. At energies typically one thousand to one million times higher, sources further than the sun (both within the Milky Way and beyond) are expected to produce a flux of particles that can be detected only through neutrinos. PMID:10588680
Measuring neutrino masses with weak lensing
Wong, Yvonne Y. Y.
2006-11-17
Weak gravitational lensing of distant galaxies by large scale structure (LSS) provides an unbiased way to map the matter distribution in the low redshift universe. This technique, based on the measurement of small distortions in the images of the source galaxies induced by the intervening LSS, is expected to become a key cosmological probe in the future. We discuss how future lensing surveys can probe the sum of the neutrino masses at the 0 05 eV level.
A neutrino mass-mixing sum rule from SO(10) and neutrinoless double beta decay
NASA Astrophysics Data System (ADS)
Buccella, F.; Chianese, M.; Mangano, G.; Miele, G.; Morisi, S.; Santorelli, P.
2017-04-01
Minimal SO(10) grand unified models provide phenomenological predictions for neutrino mass patterns and mixing. These are the outcome of the interplay of several features, namely: i) the seesaw mechanism; ii) the presence of an intermediate scale where B-L gauge symmetry is broken and the right-handed neutrinos acquire a Majorana mass; iii) a symmetric Dirac neutrino mass matrix whose pattern is close to the up-type quark one. In this framework two natural characteristics emerge. Normal neutrino mass hierarchy is the only allowed, and there is an approximate relation involving both light-neutrino masses and mixing parameters. This differs from what occurring when horizontal flavour symmetries are invoked. In this case, in fact, neutrino mixing or mass relations have been separately obtained in literature. In this paper we discuss an example of such comprehensive mixing-mass relation in a specific realization of SO(10) and, in particular, analyse its impact on the expected neutrinoless double beta decay effective mass parameter < m ee >, and on the neutrino mass scale. Remarkably a lower limit for the lightest neutrino mass is obtained ( m lightest ≳ 7 .5 × 10 -4 eV, at 3 σ level).
Constraints on the relic neutrino abundance and implications for cosmological neutrino mass limits
Bell, Nicole F.; /Fermilab
2004-01-01
The authors examine a mechanism which can lead to flavor transformation of neutrino-antineutrino asymmetries in the early universe, a process which is unavoidable when the neutrino mixing angles are large. This sets the best limit on the lepton number of the universe, and hence on the relic neutrino abundance. They also consider the consequences for the relic neutrino abundance if extra neutrino interactions are allowed, e.g., the coupling of the neutrinos to a light (compared to m{sub {nu}}) boson. For a wide range of couplings not excluded by other considerations, the relic neutrinos would annihilate to bosons at late times, and thus make a negligible contribution to the matter density today. This mechanism evades the neutrino mass limits arising from large scale structure.
Supernovae, neutrino rest mass, and the middle-energy neutrino background in the universe
NASA Astrophysics Data System (ADS)
Bisnovatyi-Kogan, G. S.; Seidov, Z. F.
Neutrinos emitted during the formation of the neutron stars and black holes form, together with relict microwave radiation and relict neutrinos, a background for the present universe. The energy of the kind of neutrino emitted in neutron star formation, at 3-30 MeV, is much greater than that of relict neutrinos and much smaller than that of the cosmic ray neutrinos; they are accordingly designated 'middle energy neutrinos' (MENs). It is presently shown that the MEN background's density, at 2-10 x 10 to the -33rd gm/cu cm, is greater than the density of relict microwave radiation and less than the density of matter. The MEN spectra presently calculated yield 0.002 to 0.008 solar neutrino units in the solar chlorine-argon detector. Possible neutrino rest mass effects are discussed for the cases of expanding universe propagation and MEN background spatial structure.
Low Temperature Magnetic Calorimeters For Neutrino Mass Direct Measurement
NASA Astrophysics Data System (ADS)
Gastaldo, L.; Porst, J. P.; von Seggern, F.; Kirsch, A.; Ranitzsch, P.; Fleischmann, A.; Enss, C.; Seidel, G. M.
2009-12-01
In the last years the mixing of the three neutrino flavor eigenstates through a unitary matrix has been experimentally proved. Presently one of the greatest challenges in neutrino physics is to establish the absolute value of the masses of the three neutrino mass eigenstates. The kinematic determination of electron neutrino and antineutrino mass by means of the analysis of calorimetric spectra of isotopes which undergo a beta or electron-capture decay, with especially low energy available for the decay itself, represents an interesting method. In fact this method is less affected by theoretical models defining branching ratio among different decay modes. For the beta decay the isotope with the lowest Q-value present in nature is the 187Re (Q about 2.5 keV) while for the electron capture decay the best candidate known is the 163Ho (Q about 2.5 keV). Since those experiments need to be extremely precise, they might suffer from unexpected systematic errors. It is therefore important to investigate in detail the performance of the detectors and the calorimetric spectrum. We present our results obtained with low temperature magnetic calorimeters designed for measuring low energy beta and electron capture spectra. We also discuss problematic and the possibly present systematic uncertainties using this kind of detectors.
Neutrinoless double beta decay and neutrino mass
NASA Astrophysics Data System (ADS)
Vergados, J. D.; Ejiri, H.; Šimkovic, F.
2016-11-01
The observation of neutrinoless double beta decay (DBD) will have important consequences. First it will signal that lepton number is not conserved and the neutrinos are Majorana particles. Second, it represents our best hope for determining the absolute neutrino mass scale at the level of a few tens of meV. To achieve the last goal, however, certain hurdles have to be overcome involving particle, nuclear and experimental physics. Particle physics is important since it provides the mechanisms for neutrinoless DBD. In this review, we emphasize the light neutrino mass mechanism. Nuclear physics is important for extracting the useful information from the data. One must accurately evaluate the relevant nuclear matrix elements (NMEs), a formidable task. To this end, we review the recently developed sophisticated nuclear structure approaches, employing different methods and techniques of calculation. We also examine the question of quenching of the axial vector coupling constant, which may have important consequences on the size of the NMEs. From an experimental point of view it is challenging, since the life times are extremely long and one has to fight against formidable backgrounds. One needs large isotopically enriched sources and detectors with good energy resolution and very low background.
Status of the KATRIN neutrino mass experiment
NASA Astrophysics Data System (ADS)
Martin, Eric; Katrin Collaboration
2016-09-01
The upcoming Karlsruhe Tritium Neutrino (KATRIN) experiment aims to explore neutrino mass down to 0.2 eV/c2 (90% CL) by measuring the shape of the tritium beta decay spectrum. Using magnetic adiabatic collimation with an electrostatic filter (MAC-E filter) KATRIN will measure the electron kinetic energy spectrum with a resolution better than one part in 104. All major components are on site and commissioning is underway, with first tritium data currently scheduled for 2017. The measurement technique will be explained along with an update on commissioning progress. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics under Award Number DE-FG02-97ER41020.
Two-loop neutrino model with exotic leptons
NASA Astrophysics Data System (ADS)
Okada, Hiroshi; Orikasa, Yuta
2016-01-01
We propose a two-loop induced neutrino mass model, in which we show some bench mark points to satisfy the observed neutrino oscillation, the constraints of lepton flavor violations, and the relic density in the coannihilation system satisfying the current upper bound on the spin independent scattering cross section with nuclei. We also discuss new sources of muon anomalous magnetic moments.
Assess the neutrino mass with micro and macro calorimeter approach
NASA Astrophysics Data System (ADS)
Giachero, A.
2017-05-01
Thanks to oscillation experiments it is now an established fact that neutrinos are massive particles. Yet, the assessment of neutrinos absolute mass scale is still an outstanding challenge in particle physics and cosmology as oscillation experiments are sensitive only to the squared mass differences of the three neutrino mass eigenstates. The mass hierarchy is not the only missing piece in the puzzle. Theories of neutrino mass generation call into play Majorana neutrinos and there are experimental observations pointing toward the existence of sterile neutrinos in addition to the three weakly interacting ones. Three experimental approaches are currently pursued: an indirect neutrino mass determination via cosmological observables, the search for neutrinoless double β-decay, and a direct measurement based on the kinematics of single β or electron capture decays. Bolometers and calorimeters are low temperature detectors used in many applications, such as astrophysics, fast spectroscopy and particle physics. In particular, sensitive calorimeters play an important role in the neutrino mass measurement and in the search for the neutrinoless double β-decay. There has been great technical progress on low temperature detectors since they were proposed for neutrino physics experiments in 1984. This general detector paradigm can be implemented in devices as small as a micrometer for sub eV radiation or as large as 1 kg for MeV scale particles. Today this technique offers the high energy resolution and scalability required for leading edges and competitive experiments addressing the still open questions in neutrino physics.
Three-loop neutrino mass model with a colored triplet scalar
NASA Astrophysics Data System (ADS)
Cheung, Kingman; Nomura, Takaaki; Okada, Hiroshi
2017-01-01
We study a variation of the Krauss-Nasri-Trodden model with a colored triplet scalar field and a colored singlet scalar field. We discuss the anomaly coming from b →s μ μ ¯, fit to the muon anomalous magnetic moment and the relic density of the Majorana-type dark matter candidate, and satisfy various constraints such as lepton flavor violations and flavor-changing neutral currents. Also, we discuss the direct constraints from the collider searches and the possibilities of detecting the new fields at the LHC.
Gravity effects on neutrino masses in split supersymmetry
Diaz, Marco Aurelio; Koch, Benjamin; Panes, Boris
2009-06-01
The mass differences and mixing angles of neutrinos can neither be explained by R-parity violating split supersymmetry nor by flavor blind quantum gravity alone. It is shown that combining both effects leads, within the allowed parameter range, to good agreement with the experimental results. The atmospheric mass is generated by supersymmetry through mixing between neutrinos and neutralinos, while the solar mass is generated by gravity through flavor blind dimension five operators. Maximal atmospheric mixing forces the tangent squared of the solar angle to be equal to 1/2. The scale of the quantum gravity operator is predicted within a 5% error, implying that the reduced Planck scale should lie around the grand unified theory scale. In this way, the model is very predictive and can be tested at future experiments.
Weighing neutrinos in Finslerian cosmological models
NASA Astrophysics Data System (ADS)
Wang, Deng; Meng, Xin-He
2017-07-01
To explore the neutrino physics in the framework of Finsler geometry, we perform constraints on five cosmological models using the most stringent constraint we can provide so far. For the first time, we give the 95% limits of the total mass of three active neutrinos Σ mν for three Finslerian models in the presence of massive neutrinos. We find that the base Finslerian model, a two-parameter extension to the Λ CDM model based on the Finsler geometry, can fit better to current data than the other four models, and that the values of constrained effective typical parameters α and β in four Finslerian models are all consistent with zero at the 1 σ confidence level (CL), indicating that four Finslerian models just deviate very slightly from the Λ CDM model. For the base Finslerian model with a constant equation of state (EoS) of dark energy (DE) and massive neutrinos, we obtain a tighter constraint on the EoS of DE, which is more stringent than Planck's prediction by one order of magnitude. For the nonflat base Finslerian model with massive neutrinos, we find that our measured value of spatial curvature is in a strong tension with a flat universe at the 2.45 σ CL. However, if fixing Σ mν=0.06 eV with a normal hierarchy, this tension vanishes, i.e., a flat universe is still preferred in the nonflat base Finslerian model. We also find that the current H0 tension can be effectively alleviated by four Finslerian models.
Neutrino Mass from Beta Decay of the Free Neutron
NASA Astrophysics Data System (ADS)
Tegen, R.; Miller, H. G.
We calculate the beta decay rate of the free neutron including effects due to (i) a neutrino mass around 1 eV, (ii) deviations from the leptonic V-A structure, (iii) nucleon form factors F1,2V (q2), GA(q2), and (iv) W- propagation. At the end-point energies linear neutrino mass effects in n -> p + e- + ¯ {ν }e are almost exclusively kinematical. If the neutrino spectrum is (almost) degenerate, neutrino oscillations cannot uniquely determine the mass of the neutrino, and direct mass determinations become necessary. The traditional Kurie plot and a partially integrated decay rate are found to be sensitive to a neutrino mass between 1 eV and 3 eV.
NASA Astrophysics Data System (ADS)
Kang, Kyungsik; Shin, Michael
1987-02-01
The light neutrino masses and their mixing angles are investigated in a class of SO(10) models with the GRSY seesaw mechanism. The models are motivated by a recent proposal on the structure of the Yukawa couplings postulated from the observed K-M angles and the strong-CP problem. The scale of the seesaw mechanism is found to be bounded from above by the invisible axion scale, leading to a lower bound on the light neutrino masses. The main results are: 0.18eV<=mv3<=100eV, mv1/mv2=O(mu/mc), and mv2/mv3=O((mc/mt)(√mumc/mt)) for the non-hierarchical structure of the right-handed neutrino mass matrix (MN), and mv2/mv3=O(mc/mt) for the hierarchical structure of MN, θeμ≅√me/mμ+exp(iηl')O(√mu/mc), θμt≅√mμ/mt-exp(iη2)O(√mc/mt), and θe/mtθμt, where η1' and η2 are some phases. With present experimental constraints on the mixing angles, νμ-ντ and νe-νμ oscillations may be observable in the next generation of experiments. Regarding the solution to the solar neutrino problem with the MSW amplification mechanism, we find that the relevant neutrino oscillation in the sun should be in the νe-νμ channel, instead of the νe-νt channel which the ``naive seesaw'' model at the GUT scale predicts. Moreover, we also find that, for the structure of MN similar to those of quarks, the existence of a light fourth generation neutrino is inevitable, if the cosmological mass density bound is to be saturated by the light neutrino masses and the solar neutrino problem is solved by the MSW mechanism.
Neutrino mass matrix with the seesaw mechanism and two-loop mass splitting
NASA Astrophysics Data System (ADS)
Grimus, W.; Lavoura, L.
2000-11-01
We propose a model which uses the seesaw mechanism and the lepton number L¯=Le-Lμ-Lτ to achieve the neutrino mass spectrum m1=m2 and m3=0, together with a lepton mixing matrix U with Ue3=0. In this way, we accommodate atmospheric neutrino oscillations. A small mass splitting m1>m2 is generated by breaking L¯ spontaneously and using Babu's two-loop mechanism. This allows us to incorporate either the ``just so'' or the LOW solution of the solar-neutrino problem, with maximal mixing, into the model. The resulting mass matrix has three parameters only, since L¯ breaking leads exclusively to a non-zero ee matrix element.
Common origin of neutrino mass, dark matter and Dirac leptogenesis
NASA Astrophysics Data System (ADS)
Borah, Debasish; Dasgupta, Arnab
2016-12-01
We study the possibility of generating tiny Dirac neutrino masses at one loop level through the scotogenic mechanism such that one of the particles going inside the loop can be a stable cold dark matter (DM) candidate. Majorana mass terms of singlet fermions as well as tree level Dirac neutrino masses are prevented by incorporating the presence of additional discrete symmetries in a minimal fashion, which also guarantee the stability of the dark matter candidate. Due to the absence of total lepton number violation, the observed baryon asymmetry of the Universe is generated through the mechanism of Dirac leptogenesis where an equal and opposite amount of leptonic asymmetry is generated in the left and right handed sectors which are prevented from equilibration due to tiny Dirac Yukawa couplings. Dark matter relic abundance is generated through its usual freeze-out at a temperature much below the scale of leptogenesis. We constrain the relevant parameter space from neutrino mass, baryon asymmetry, Planck bound on dark matter relic abundance, and latest LUX bound on spin independent DM-nucleon scattering cross section. We also discuss the charged lepton flavour violation (μ → e γ) and electric dipole moment of electron in this model in the light of the latest experimental data and constrain the parameter space of the model.
Upper bound on neutrino mass based on T2K neutrino timing measurements
NASA Astrophysics Data System (ADS)
Abe, K.; Adam, J.; Aihara, H.; Akiri, T.; Andreopoulos, C.; Aoki, S.; Ariga, A.; Assylbekov, S.; Autiero, D.; Barbi, M.; Barker, G. J.; Barr, G.; Bartet-Friburg, P.; Bass, M.; Batkiewicz, M.; Bay, F.; Berardi, V.; Berger, B. E.; Berkman, S.; Bhadra, S.; Blaszczyk, F. d. M.; Blondel, A.; Bojechko, C.; Bolognesi, S.; 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.; Chikuma, N.; Christodoulou, G.; Clifton, A.; Coleman, J.; Coleman, S. J.; Collazuol, G.; Connolly, K.; Cremonesi, L.; Dabrowska, A.; Danko, I.; Das, R.; Davis, S.; de Perio, P.; De Rosa, G.; Dealtry, T.; Dennis, S. R.; Densham, C.; Dewhurst, D.; Di Lodovico, F.; Di Luise, S.; Dolan, S.; Drapier, O.; Duboyski, T.; Duffy, K.; Dumarchez, J.; Dytman, S.; Dziewiecki, M.; Emery-Schrenk, S.; Ereditato, A.; Escudero, L.; Feusels, T.; Finch, A. J.; Fiorentini, G. A.; Friend, M.; Fujii, Y.; Fukuda, Y.; Furmanski, A. P.; Galymov, V.; Garcia, A.; Giffin, S.; Giganti, C.; Gilje, K.; Goeldi, D.; Golan, T.; Gonin, M.; Grant, N.; Gudin, D.; Hadley, D. R.; Haegel, L.; Haesler, A.; Haigh, M. D.; Hamilton, P.; Hansen, D.; Hara, T.; Hartz, M.; Hasegawa, T.; Hastings, N. C.; Hayashino, T.; Hayato, Y.; Hearty, C.; Helmer, R. L.; Hierholzer, M.; Hignight, J.; Hillairet, A.; Himmel, A.; Hiraki, T.; Hirota, S.; Holeczek, J.; Horikawa, S.; Hosomi, F.; Huang, K.; Ichikawa, A. K.; Ieki, K.; Ieva, M.; Ikeda, M.; Imber, J.; Insler, J.; Irvine, T. J.; Ishida, T.; Ishii, T.; Iwai, E.; Iwamoto, K.; Iyogi, K.; Izmaylov, A.; Jacob, A.; Jamieson, B.; Jiang, M.; Johnson, R. A.; Johnson, S.; Jo, J. H.; Jonsson, P.; Jung, C. K.; Kabirnezhad, M.; Kaboth, A. C.; Kajita, T.; Kakuno, H.; Kameda, J.; Kanazawa, Y.; Karlen, D.; Karpikov, I.; Katori, T.; Kearns, E.; Khabibullin, M.; Khotjantsev, A.; Kielczewska, D.; Kikawa, T.; Kilinski, A.; Kim, J.; King, S.; Kisiel, J.; Kitching, P.; Kobayashi, T.; Koch, L.; Koga, T.; Kolaceke, A.; Konaka, A.; Kopylov, A.; Kormos, L. L.; Korzenev, A.; Koshio, Y.; Kropp, W.; Kubo, H.; Kudenko, Y.; Kurjata, R.; Kutter, T.; Lagoda, J.; Lamont, I.; Larkin, E.; Laveder, M.; Lawe, M.; Lazos, M.; Lindner, T.; Lister, C.; Litchfield, R. P.; Longhin, A.; Lopez, J. P.; Ludovici, L.; Magaletti, L.; Mahn, K.; Malek, M.; Manly, S.; Marino, A. D.; Marteau, J.; Martin, J. F.; Martins, P.; Martynenko, S.; Maruyama, T.; Matveev, V.; Mavrokoridis, K.; Mazzucato, E.; McCarthy, M.; McCauley, N.; McFarland, K. S.; McGrew, C.; Mefodiev, A.; Metelko, C.; Mezzetto, M.; Mijakowski, P.; Miller, C. A.; Minamino, A.; Mineev, O.; Missert, A.; Miura, M.; Moriyama, S.; Mueller, Th. A.; Murakami, A.; Murdoch, M.; Murphy, S.; Myslik, J.; Nakadaira, T.; Nakahata, M.; Nakamura, K. G.; Nakamura, K.; Nakayama, S.; Nakaya, T.; Nakayoshi, K.; Nantais, C.; Nielsen, C.; Nirkko, M.; Nishikawa, K.; Nishimura, Y.; Nowak, J.; O'Keeffe, H. M.; Ohta, R.; Okumura, K.; Okusawa, T.; Oryszczak, W.; Oser, S. M.; Ovsyannikova, T.; Owen, R. A.; Oyama, Y.; Palladino, V.; Palomino, J. L.; Paolone, V.; Payne, D.; Perevozchikov, O.; Perkin, J. D.; Petrov, Y.; Pickard, L.; Pinzon Guerra, E. S.; Pistillo, C.; Plonski, P.; Poplawska, E.; Popov, B.; Posiadala-Zezula, M.; Poutissou, J.-M.; Poutissou, R.; Przewlocki, P.; Quilain, B.; Radicioni, E.; Ratoff, P. N.; Ravonel, M.; Rayner, M. A. M.; Redij, A.; Reeves, M.; Reinherz-Aronis, E.; Riccio, C.; Rodrigues, P. A.; Rojas, P.; Rondio, E.; Roth, S.; Rubbia, A.; Ruterbories, D.; Rychter, A.; 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.; Shah, R.; Shaker, F.; Shaw, D.; Shiozawa, M.; Short, S.; Shustrov, Y.; Sinclair, P.; Smith, B.; Smy, M.; Sobczyk, J. T.; Sobel, H.; Sorel, M.; Southwell, L.; Stamoulis, P.; Steinmann, J.; Still, B.; Suda, Y.; Suzuki, A.; Suzuki, K.; Suzuki, S. Y.; Suzuki, Y.; Tacik, R.; Tada, M.; Takahashi, S.; Takeda, A.; Takeuchi, Y.; Tanaka, H. K.; Tanaka, H. A.; Tanaka, M. M.; Terhorst, D.; Terri, R.; Thompson, L. F.; Thorley, A.; Tobayama, S.; Toki, W.; Tomura, T.; Totsuka, Y.; Touramanis, C.; Tsukamoto, T.; Tzanov, M.; Uchida, Y.; Vacheret, A.; Vagins, M.; Vasseur, G.; Wachala, T.; Wakamatsu, K.; Walter, C. W.; Wark, D.; Warzycha, W.; Wascko, M. O.; Weber, A.; Wendell, R.; Wilkes, R. J.; Wilking, M. J.; Wilkinson, C.; Williamson, Z.; Wilson, J. R.; Wilson, R. J.; Wongjirad, T.; Yamada, Y.; Yamamoto, K.; Yanagisawa, C.; Yano, T.; Yen, S.; Yershov, N.; Yokoyama, M.; Yoo, J.; Yoshida, K.; Yuan, T.; Yu, M.; Zalewska, A.; Zalipska, J.; Zambelli, L.; Zaremba, K.; Ziembicki, M.; Zimmerman, E. D.; Zito, M.; Żmuda, J.; T2K Collaboration
2016-01-01
The Tokai to Kamioka (T2K) long-baseline neutrino experiment consists of a muon neutrino beam, produced at the J-PARC accelerator, a near detector complex and a large 295-km-distant far detector. The present work utilizes the T2K event timing measurements at the near and far detectors to study neutrino time of flight as a function of derived neutrino energy. Under the assumption of a relativistic relation between energy and time of flight, constraints on the neutrino rest mass can be derived. The sub-GeV neutrino beam in conjunction with timing precision of order tens of ns provide sensitivity to neutrino mass in the few MeV /c2 range. We study the distribution of relative arrival times of muon and electron neutrino candidate events at the T2K far detector as a function of neutrino energy. The 90% C.L. upper limit on the mixture of neutrino mass eigenstates represented in the data sample is found to be mν2<5.6 MeV2/c4 .
NASA Astrophysics Data System (ADS)
Cheung, Kingman; Nomura, Takaaki; Okada, Hiroshi
2016-12-01
We propose a one-loop radiative Majorana-type neutrino-mass matrix without any kind of additional symmetries by introducing two leptoquark-like bosons only. In this scenario, we show that the anomaly appearing in the process b →s ℓℓ ¯ can be explained without any conflicts against various constraints such as lepton-flavor violations, flavor-changing neutral currents, oblique parameters Δ S , Δ T , and the Drell-Yan process. We make the predictions for the flavor-violating lepton-pair production (e μ , e τ , and μ τ ) at the LHC, as well as the cross sections for pair production of these leptoquark-like bosons.
Challenging the Neutrino Mass with Cuore
NASA Astrophysics Data System (ADS)
Ferroni, F.
2008-06-01
One of the fundamental questions still open in elementary particle is the nature of the neutrino mass. Whether Dirac or Majorana, its knowledge would deeply impact the development of the field. Double Beta Decay experiments are, although extremely challenging, the only way known that might give an answer to the question. In this paper one of the second generation experiment that aims to get the sensitivity for probing the inverted hierarchy will be discussed. It is CUORE, in preparation at the Gran Sasso underground laboratories of INFN.
Degeneracy effects of neutrino mass ejection in supernovae
NASA Technical Reports Server (NTRS)
Mazurek, T. J.
1974-01-01
A neutrino mechanism is discussed in order to explain supernovae in massive stars. An argument is presented for supernova mass ejection through leptonic neutrino transport characteristics suppressed by the arbitrary zero chemical potential condition. Results show that lepton conservation effects may be important in supernova neutrino transport. At low temperature and density the diffusion approximation becomes less precise because of the long mean free paths of low energy neutrinos. The amount of equilibrium neutrino spectrum affected here is small over most of the collapsing supernova structure.
Sneutrino dark matter in gauged inverse seesaw models for neutrinos.
An, Haipeng; Dev, P S Bhupal; Cai, Yi; Mohapatra, R N
2012-02-24
Extending the minimal supersymmetric standard model to explain small neutrino masses via the inverse seesaw mechanism can lead to a new light supersymmetric scalar partner which can play the role of inelastic dark matter (IDM). It is a linear combination of the superpartners of the neutral fermions in the theory (the light left-handed neutrino and two heavy standard model singlet neutrinos) which can be very light with mass in ~5-20 GeV range, as suggested by some current direct detection experiments. The IDM in this class of models has keV-scale mass splitting, which is intimately connected to the small Majorana masses of neutrinos. We predict the differential scattering rate and annual modulation of the IDM signal which can be testable at future germanium- and xenon-based detectors.
Prospects for constraining neutrino mass using Planck and Lyman-{alpha} forest data
Gratton, Steven; Lewis, Antony; Efstathiou, George
2008-04-15
In this paper we investigate how well Planck and Lyman-{alpha} forest data will be able to constrain the sum of the neutrino masses, and thus, in conjunction with flavor oscillation experiments, be able to determine the absolute masses of the neutrinos. It seems possible that Planck, together with a Lyman-{alpha} survey, will be able to put pressure on an inverted hierarchial model for the neutrino masses. However, even for optimistic assumptions of the precision of future Lyman-{alpha} data sets, it will not be possible to confirm a minimal-mass normal hierarchy.
NASA Astrophysics Data System (ADS)
Dutta, Rupak; Ch, Upender; Giri, Anjan K.; Sahu, Narendra
2014-08-01
We discuss the role of lightest neutrino mass (m0) in the neutrino mass matrix, defined in a flavor basis, through a bottom-up approach using the current neutrino oscillation data. We find that if m0 < 10-3eV, then the deviation δMν in the neutrino mass matrix from a tree-level, say tribimaximal neutrino mass matrix, does not depend on m0. As a result δMν's are exactly predicted in terms of the experimentally determined quantities such as solar and atmospheric mass squared differences and the mixing angles. On the other hand for m0 ≳10-3eV, δMν strongly depends on m0 and hence cannot be determined within the knowledge of oscillation parameters alone. In this limit, we provide an exponential parametrization for δMν for all values of m0 such that it can factorize the m0 dependency of δMν from rest of the oscillation parameters. This helps us in finding δMν as a function of the solar and atmospheric mass squared differences and the mixing angles for all values of m0. We use this information to build up a model of neutrino masses and mixings in a top-down scenario which can predict large θ13 perturbatively.
NASA Astrophysics Data System (ADS)
Wang, Weijian; Guo, Shu-Yuan; Wang, Zhi-Gang
2016-04-01
In this paper, we study the cofactor 2 zero neutrino mass matrices with the Fritzsch-type structure in charged lepton mass matrix (CLMM). In the numerical analysis, we perform a scan over the parameter space of all the 15 possible patterns to get a large sample of viable scattering points. Among the 15 possible patterns, three of them can accommodate the latest lepton mixing and neutrino mass data. We compare the predictions of the allowed patterns with their counterparts with diagonal CLMM. In this case, the severe cosmology bound on the neutrino mass set a strong constraint on the parameter space, rendering two patterns only marginally allowed. The Fritzsch-type CLMM will have impact on the viable parameter space and give rise to different phenomenological predictions. Each allowed pattern predicts the strong correlations between physical variables, which is essential for model selection and can be probed in future experiments. It is found that under the no-diagonal CLMM, the cofactor zeros structure in neutrino mass matrix is unstable as the running of renormalization group (RG) from seesaw scale to the electroweak scale. A way out of the problem is to propose the flavor symmetry under the models with a TeV seesaw scale. The inverse seesaw model and a loop-induced model are given as two examples.
Astrophysics and cosmology closing in on neutrino masses
NASA Technical Reports Server (NTRS)
Dar, Arnon
1990-01-01
Massive neutrinos are expected in most grand unified theories that attempt to unify the strong and electroweak interactions. So far, heroic laboratory experiments have yielded only upper bounds on the masses of the elusive neutrinos. These bounds, however, are not very restrictive and cannot even exclude the possibility that the dark matter in the universe consists of neutrinos. The astrophysical and cosmological bounds on the masses of the muon and tau neutrinos, m(nu sub mu) and m(nu sub tau), which already are much more restrictive than the laboratory bounds, and the laboratory bound on the mass of the electron neutrino, m(nu sub e) can be improved significantly by future astrophysical and cosmological observations that perhaps will pin down the neutrino masses. Indeed, the recent results from the solar neutrino experiments combined with the seesaw mechanism for generating neutrino masses suggest that m(nu sub e) of about 10 to the -8th electron volts, m(nu sub mu) of about 0.001 electron volts, and m(nu sub tau) of about 10 electron volts, which can be tested in the near future by solar neutrino and accelerator experiments.
Strong thermal leptogenesis and the absolute neutrino mass scale
Bari, Pasquale Di; King, Sophie E.; Fiorentin, Michele Re E-mail: sk1806@soton.ac.uk
2014-03-01
We show that successful strong thermal leptogenesis, where the final asymmetry is independent of the initial conditions and in particular a large pre-existing asymmetry is efficiently washed-out, favours values of the lightest neutrino mass m{sub 1}∼>10 meV for normal ordering (NO) and m{sub 1}∼>3 meV for inverted ordering (IO) for models with orthogonal matrix entries respecting |Ω{sub ij}{sup 2}|∼<2. We show analytically why lower values of m{sub 1} require a higher level of fine tuning in the seesaw formula and/or in the flavoured decay parameters (in the electronic for NO, in the muonic for IO). We also show how this constraint exists thanks to the measured values of the neutrino mixing angles and could be tightened by a future determination of the Dirac phase. Our analysis also allows us to place a more stringent constraint for a specific model or class of models, such as SO(10)-inspired models, and shows that some models cannot realise strong thermal leptogenesis for any value of m{sub 1}. A scatter plot analysis fully supports the analytical results. We also briefly discuss the interplay with absolute neutrino mass scale experiments concluding that they will be able in the coming years to either corner strong thermal leptogenesis or find positive signals pointing to a non-vanishing m{sub 1}. Since the constraint is much stronger for NO than for IO, it is very important that new data from planned neutrino oscillation experiments will be able to solve the ambiguity.
Measurable neutrino mass scale in A{sub 4}xSU(5)
Antusch, S.; Spinrath, M.; King, Stephen F.
2011-01-01
We propose a supersymmetric A{sub 4}xSU(5) model of quasidegenerate neutrinos which predicts the effective neutrino mass m{sub ee} relevant for neutrinoless double beta decay to be proportional to the neutrino mass scale, thereby allowing its determination approximately independently of unknown Majorana phases. Such a natural quasidegeneracy is achieved by using A{sub 4} family symmetry (as an example of a non-Abelian family symmetry with real triplet representations) to enforce a contribution to the neutrino mass matrix proportional to the identity. Tribimaximal neutrino mixing as well as quark CP violation with {alpha}{approx_equal}90 deg. d a leptonic CP phase {delta}{sub MNS{approx_equal}}90 deg. arise from the breaking of the A{sub 4} family symmetry by the vacuum expectation values of four 'flavon' fields pointing in specific postulated directions in flavor space.
NASA Astrophysics Data System (ADS)
Aoki, Mayumi; Kanemura, Shinya; Sakurai, Kodai; Sugiyama, Hiroaki
2016-12-01
We investigate how observations of the lepton flavor violating decay of the Higgs boson (h → ℓℓ‧) can narrow down models of neutrino mass generation mechanisms, which were systematically studied in Refs. [1,2] by focusing on the combination of new Yukawa coupling matrices with leptons. We find that a wide class of models for neutrino masses can be excluded if evidence for h → ℓℓ‧ is really obtained in the current or future collider experiments. In particular, simple models of Majorana neutrino masses cannot be compatible with the observation of h → ℓℓ‧. It is also found that some of the simple models to generate masses of Dirac neutrinos radiatively can be compatible with a significant rate of the h → ℓℓ‧ process.
Blennow, Mattias
2008-06-01
We discuss the effects of neutrino mixing and the neutrino mass hierarchy when considering the capture of the cosmic neutrino background (CNB) on radioactive nuclei. The implications of mixing and hierarchy at future generations of tritium decay experiments are considered. We find that the CNB should be detectable at these experiments provided that the resolution for the kinetic energy of the outgoing electron can be pushed to a few 0.01 eV for the scenario with inverted neutrino mass hierarchy, about an order of magnitude better than that of the upcoming KATRIN experiment. Another order of magnitude improvement is needed in the case of normal neutrino mass hierarchy. We also note that mixing effects generally make the prospects for CNB detection worse due to an increased maximum energy of the normal beta decay background.
Experimental constraints on the neutrino oscillations and a simple model of three-flavor mixing
Raczka, P.A.; Szymacha, A. ); Tatur, S. )
1994-02-01
A simple model of neutrino mixing is considered which contains only one right-handed neutrino field coupled, via the mass term, to the three usual left-handed fields. This is the simplest model that allows for three-flavor neutrino oscillations. The existing experimental limits on the neutrino oscillations are used to obtain constraints on the two free-mixing parameters of the model. A specific sum rule relating the oscillation probabilities of different flavors is derived.
Neutrino mass effects on the CMB polarization with PMF
Kojima, Kazuhiko; Kajino, Toshitaka; Mathews, Grant J.
2009-05-04
Our previous work showed that if a primordial magnetic field (PMF) was present during photon decoupling and afterward, massive neutrinos affect all modes of the CMB. This is because of the compensation of anisotropic stress between the neutrinos and the PMF. In order to study the observability of this new effect, we need careful analysis of the passive mode generated by the PMF. Here, we focus on the polarization of the CMB and study the observability of the finite neutrino mass effect.
Active and sterile neutrino mass effects on beta decay spectra
Boillos, Juan Manuel; Moya de Guerra, Elvira
2013-06-10
We study the spectra of the emitted charged leptons in charge current weak nuclear processes to analyze the effect of neutrino masses. Standard active neutrinos are studied here, with masses of the order of 1 eV or lower, as well as sterile neutrinos with masses of a few keV. The latter are warm dark matter (WDM) candidates hypothetically produced or captured as small mixtures with the active neutrinos. We compute differential decay or capture rates spectra in weak charged processes of different nuclei ({sup 3}H, {sup 187}Re, {sup 107}Pd, {sup 163}Ho, etc) using different masses of both active and sterile neutrinos and different values of the mixing parameter.
Cosmology of mass-varying neutrinos driven by quintessence: Theory and observations
Brookfield, A.W.; Bruck, C. van de; Mota, D.F.; Tocchini-Valentini, D.
2006-04-15
The effects of mass-varying neutrinos on cosmic microwave background (CMB) anisotropies and large scale structures (LSS) are studied. In these models, dark energy and neutrinos are coupled such that the neutrino masses are functions of the scalar field playing the role of dark energy. We begin by describing the cosmological background evolution of such a system. It is pointed out that, similar to models with a dark matter/dark energy interaction, the apparent equation of state measured with SNIa can be smaller than -1. We then discuss the effect of mass-varying neutrinos on the CMB anisotropies and the matter power spectrum. A suppression of power in the CMB power spectrum at large angular scales is usually observed. We give an explanation for this behavior and discuss different couplings and quintessence potentials to show the generality of the results obtained. We perform a likelihood analysis using wide-ranging SNIa, CMB, and LSS observations to assess whether such theories are viable. Treating the neutrino mass as a free parameter we find that the constraints on the coupling are weak, since CMB and LSS surveys give only upper bounds on the neutrino mass. However, fixing a priori the neutrino masses, we find that there is some evidence that the existence of such a coupling is actually preferred by current cosmological data over the standard {lambda}CDM cosmology.
Diffuse supernova neutrinos: oscillation effects, stellar cooling and progenitor mass dependence
Lunardini, Cecilia; Tamborra, Irene E-mail: tamborra@mpp.mpg.de
2012-07-01
We estimate the diffuse supernova neutrino background (DSNB) using the recent progenitor-dependent, long-term supernova simulations from the Basel group and including neutrino oscillations at several post-bounce times. Assuming multi-angle matter suppression of collective effects during the accretion phase, we find that oscillation effects are dominated by the matter-driven MSW resonances, while neutrino-neutrino collective effects contribute at the 5–10% level. The impact of the neutrino mass hierarchy, of the time-dependent neutrino spectra and of the diverse progenitor star population is 10% or less, small compared to the uncertainty of at least 25% of the normalization of the supernova rate. Therefore, assuming that the sign of the neutrino mass hierarchy will be determined within the next decade, the future detection of the DSNB will deliver approximate information on the MSW-oscillated neutrino spectra. With a reliable model for neutrino emission, its detection will be a powerful instrument to provide complementary information on the star formation rate and for learning about stellar physics.
Form invariance and symmetry in the neutrino mass matrix
Lashin, E. I.; Nasri, S.; Malkawi, E.; Chamoun, N.
2011-01-01
We present the general form of the unitary matrices keeping invariant the Majorana neutrino mass matrix of specific texture suitable for explaining oscillation data. In the case of the tri-bimaximal pattern with two degenerate masses, we give a specific realization of the underlying U(1) symmetry which can be uplifted to a symmetry in a complete theory including charged leptons. For this, we present a model with three light SM-like Higgs doublets and one heavy Higgs triplet and find that one can accommodate the hierarchy of the charged-lepton masses. The lepton mass spectrum can also be achieved in another model extending the SM with three SM-singlet scalars transforming nontrivially under the flavor symmetry. We discuss how such a model has room for generating enough baryon asymmetry through leptogenesis in the framework of type-I and -II seesaw mechanisms.
Leptogenesis, neutrino masses and gauge unification
NASA Astrophysics Data System (ADS)
Cosme, N.
2004-08-01
Leptogenesis is considered in its natural context where Majorana neutrinos fit in a gauge unification scheme and therefore couple to some extra gauge bosons. The masses of some of these gauge bosons are expected to be similar to those of the heavy Majorana particles, and this can have important consequences for leptogenesis. In fact, the effect can go both ways. Stricter bounds are obtained on one hand due to the dilution of the CP-violating effect by new decay and scattering channels, while, in a re-heating scheme, the presence of gauge couplings facilitates the re-population of the Majorana states. The latter effect allows in particular for smaller Dirac couplings.
Tsirigotis, A. G.; Collaboration: KM3NeT Collaboration
2014-11-18
With the measurement of a non zero value of the θ{sub 13} neutrino mixing parameter, interest in neutrinos as source of the baryon asymmetry of the universe has increased. Among the measurements of a rich and varied program in near future neutrino physics is the determination of the mass hierarchy. We present the status of a study of the feasibility of using a densely instrumented undersea neutrino detector to determine the mass hierarchy, utilizing the Mikheyev-Smirnov-Wolfenstein (MSW) effect on atmospheric neutrino oscillations. The detector will use technology developed for KM3NeT. We present the systematic studies of the optimization of a detector in the required 5–10 GeV energy regime. These studies include new tracking and interaction identification algorithms as well as geometrical optimizations of the detector.
Can electron capture tell us the mass of the neutrino?
NASA Astrophysics Data System (ADS)
Faessler, Amand; Šimkovic, F.
2016-04-01
The neutrino masses are one of the most important open problems in particle physics. Presently major efforts are underway to measure the electron antineutrino-mass by the triton beta decay [1] and the effective Majorana neutrino mass by the double beta decay [2]. The best way to determine the neutrino mass by electron capture was assumed to be in {}163{Ho}. The total decay energy of the excited daughter atom has for all excitations the same upper energy limit of the Q-value minus the mass of the electron neutrino. Recently Robertson [3] claimed, that the excitation of the two-hole states makes the determination of the neutrino mass by this method practically impossible. But Faessler and Simkovic [4] showed, that the influence of the two-hole states is less than 1% near the Q-value, the area relevant for the determination of the neutrino mass. Even weaker are the contributions of the three-hole states [5]. The upper end of the calorimetric deexcitation spectrum of Dy is dominated by the highest energy one-hole resonance. With a Lorentzian profile of this resonance one has to fit after including the experimental sensitivity four parameters: (1) the neutrino mass, (2) the Q-value, (3) the width of the resonance and (4) its strength. This contribution discusses the problems of the determination of the neutrino mass by electron capture in {}163{Ho}. The conclusion of this work is, that the determination of the electron neutrino mass by electron capture in {}163{Ho} is difficult, but (probably) not impossible.
Probing the origins of neutrino mass with supernova data.
Davoudiasl, Hooman; Huber, Patrick
2005-11-04
We study type II supernova signatures of neutrino mass generation via symmetry breaking at a scale in the range from keV to MeV. The scalar responsible for symmetry breaking is thermalized in the supernova core and restores the symmetry. The neutrinos from scalar decays have about half the average energy of thermal neutrinos. The Bose-Einstein distribution of the scalars can be established with a megaton water Cerenkov detector. The discovery of the bimodal neutrino flux is, however, well within the reach of the Super-Kamiokande detector, without a detailed knowledge of the supernova parameters.
Towards a unified model of neutrino-nucleus reactions for neutrino oscillation experiments
NASA Astrophysics Data System (ADS)
Nakamura, S. X.; Kamano, H.; Hayato, Y.; Hirai, M.; Horiuchi, W.; Kumano, S.; Murata, T.; Saito, K.; Sakuda, M.; Sato, T.; Suzuki, Y.
2017-05-01
A precise description of neutrino-nucleus reactions will play a key role in addressing fundamental questions such as the leptonic CP violation and the neutrino mass hierarchy through analyzing data from next-generation neutrino oscillation experiments. The neutrino energy relevant to the neutrino-nucleus reactions spans a broad range and, accordingly, the dominant reaction mechanism varies across the energy region from quasi-elastic scattering through nucleon resonance excitations to deep inelastic scattering. This corresponds to transitions of the effective degree of freedom for theoretical description from nucleons through meson-baryon to quarks. The main purpose of this review is to report our recent efforts towards a unified description of the neutrino-nucleus reactions over the wide energy range; recent overall progress in the field is also sketched. Starting with an overview of the current status of neutrino-nucleus scattering experiments, we formulate the cross section to be commonly used for the reactions over all the energy regions. A description of the neutrino-nucleon reactions follows and, in particular, a dynamical coupled-channels model for meson productions in and beyond the Δ (1232) region is discussed in detail. We then discuss the neutrino-nucleus reactions, putting emphasis on our theoretical approaches. We start the discussion with electroweak processes in few-nucleon systems studied with the correlated Gaussian method. Then we describe quasi-elastic scattering with nuclear spectral functions, and meson productions with a Δ -hole model. Nuclear modifications of the parton distribution functions determined through a global analysis are also discussed. Finally, we discuss issues to be addressed for future developments.
Towards a unified model of neutrino-nucleus reactions for neutrino oscillation experiments.
Nakamura, S X; Kamano, H; Hayato, Y; Hirai, M; Horiuchi, W; Kumano, S; Murata, T; Saito, K; Sakuda, M; Sato, T; Suzuki, Y
2017-05-01
A precise description of neutrino-nucleus reactions will play a key role in addressing fundamental questions such as the leptonic CP violation and the neutrino mass hierarchy through analyzing data from next-generation neutrino oscillation experiments. The neutrino energy relevant to the neutrino-nucleus reactions spans a broad range and, accordingly, the dominant reaction mechanism varies across the energy region from quasi-elastic scattering through nucleon resonance excitations to deep inelastic scattering. This corresponds to transitions of the effective degree of freedom for theoretical description from nucleons through meson-baryon to quarks. The main purpose of this review is to report our recent efforts towards a unified description of the neutrino-nucleus reactions over the wide energy range; recent overall progress in the field is also sketched. Starting with an overview of the current status of neutrino-nucleus scattering experiments, we formulate the cross section to be commonly used for the reactions over all the energy regions. A description of the neutrino-nucleon reactions follows and, in particular, a dynamical coupled-channels model for meson productions in and beyond the [Formula: see text](1232) region is discussed in detail. We then discuss the neutrino-nucleus reactions, putting emphasis on our theoretical approaches. We start the discussion with electroweak processes in few-nucleon systems studied with the correlated Gaussian method. Then we describe quasi-elastic scattering with nuclear spectral functions, and meson productions with a [Formula: see text]-hole model. Nuclear modifications of the parton distribution functions determined through a global analysis are also discussed. Finally, we discuss issues to be addressed for future developments.
Leptoquark mechanism of neutrino masses within the grand unification framework
NASA Astrophysics Data System (ADS)
Doršner, Ilja; Fajfer, Svjetlana; Košnik, Nejc
2017-06-01
We demonstrate the viability of the one-loop neutrino mass mechanism within the framework of grand unification when the loop particles comprise scalar leptoquarks (LQs) and quarks of the matching electric charge. This mechanism can be implemented in both supersymmetric and non-supersymmetric models and requires the presence of at least one LQ pair. The appropriate pairs for the neutrino mass generation via the up-type and down-type quark loops are S_3-R_2 and S_{1, 3}-\\tilde{R}_2, respectively. We consider two distinct regimes for the LQ masses in our analysis. The first regime calls for very heavy LQs in the loop. It can be naturally realized with the S_{1, 3}-\\tilde{R}_2 scenarios when the LQ masses are roughly between 10^{12} and 5 × 10^{13} GeV. These lower and upper bounds originate from experimental limits on partial proton decay lifetimes and perturbativity constraints, respectively. Second regime corresponds to the collider accessible LQs in the neutrino mass loop. That option is viable for the S_3-\\tilde{R}_2 scenario in the models of unification that we discuss. If one furthermore assumes the presence of the type II see-saw mechanism there is an additional contribution from the S_3-R_2 scenario that needs to be taken into account beside the type II see-saw contribution itself. We provide a complete list of renormalizable operators that yield necessary mixing of all aforementioned LQ pairs using the language of SU(5). We furthermore discuss several possible embeddings of this mechanism in SU(5) and SO(10) gauge groups.
Neutrino mass spectrum and future beta decay experiments
NASA Astrophysics Data System (ADS)
Farzan, Y.; Peres, O. L. G.; Smirnov, A. Yu.
2001-09-01
We study the discovery potential of future beta decay experiments on searches for the neutrino mass in the sub-eV range, and, in particular, KATRIN experiment with sensitivity m>0.3 eV. Effects of neutrino mass and mixing on the beta decay spectrum in the neutrino schemes which explain the solar and atmospheric neutrino data are discussed. The schemes which lead to observable effects contain one or two sets of quasi-degenerate states. Future beta decay measurements will allow to check the three-neutrino scheme with mass degeneracy, moreover, the possibility appears to measure the CP-violating Majorana phase. Effects in the four-neutrino schemes which can also explain the LSND data are strongly restricted by the results of Bugey and CHOOZ oscillation experiments: apart from bending of the spectrum and the shift of the end point one expects appearance of small kink of (<2%) size or suppressed tail after bending of the spectrum with rate below 2% of the expected rate for zero neutrino mass. We consider possible implications of future beta decay experiments for the neutrino mass spectrum, the determination of the absolute scale of neutrino mass and for establishing the nature of neutrinos. We show that beta decay measurements in combination with data from the oscillation and double beta decay experiments will allow to establish the structure of the scheme (hierarchical or non-hierarchical), the type of the hierarchy or ordering of states (normal or inverted) and to measure the relative CP-violating phase in the solar pair of states.
Unifying inflation and dark matter with neutrino masses.
Allahverdi, Rouzbeh; Dutta, Bhaskar; Mazumdar, Anupam
2007-12-31
We propose a simple model where a gauge-invariant inflaton is responsible for cosmic inflation and generates the seed for structure formation, while its relic thermal abundance explains the missing matter of the Universe in the form of cold dark matter. The inflaton self-coupling also explains the observed neutrino masses. All the virtues can be attained in a minimal extension of the standard model gauge group around the TeV scale. We can also unveil these properties of an inflaton in forthcoming space and ground based experiments.
An alternative method of determining the neutrino mass ordering in reactor neutrino experiments
NASA Astrophysics Data System (ADS)
Bilenky, S. M.; Capozzi, F.; Petcov, S. T.
2017-09-01
We discuss a novel alternative method of determining the neutrino mass ordering in medium baseline experiments with reactor antineutrinos. Results on the potential sensitivity of the new method are also presented.
Predictive models of large neutrino mixing angles
Barr, S.M.
1997-02-01
Several experimental results could be interpreted as evidence that certain neutrino mixing angles are large, of order unity. However, in the context of grand unified models the neutrino angles come out characteristically to be small, like the KM angles. It is shown how to construct simple grand-unified models in which neutrino angles are not only large but completely predicted with some precision. Six models are presented for illustration. {copyright} {ital 1997} {ital The American Physical Society}
Measuring neutrino mass imprinted on the anisotropic galaxy clustering
NASA Astrophysics Data System (ADS)
Oh, Minji; Song, Yong-Seon
2017-04-01
The anisotropic galaxy clustering of large scale structure observed by the Baryon Oscillation Spectroscopic Survey Data Release 11 is analyzed to probe the sum of neutrino masses in the small mν lesssim 1 eV limit in which the early broadband shape determined before the last scattering surface is immune from the variation of mν. The signature of mν is imprinted on the altered shape of the power spectrum at later epoch, which provides an opportunity to access the non-trivial mν through the measured anisotropic correlation function in redshift space (hereafter RSD instead of Redshift Space Distortion). The non-linear RSD corrections with massive neutrinos in the quasi linear regime are approximately estimated using one-loop order terms. We suggest an approach to probe mν simultaneously with all other distance measures and coherent growth functions, exploiting this deformation of the early broadband shape of the spectrum at later epoch. If the origin of cosmic acceleration is unknown, mν is poorly determined after marginalizing over all other observables. However, we find that the measured distances and coherent growth functions are minimally affected by the presence of mild neutrino mass. Although the standard model of cosmic acceleration is assumed to be the cosmological constant, the constraint on mν is little improved. Interestingly, the measured Cosmic Microwave Background (hereafter CMB) distance to the last scattering surface sharply slices the degeneracy between the matter content and mν, and the mν is observed to be mν = 0.19+0.28-0.17 eV which is different from massless neutrino at 68% confidence.
Molecular effects in the neutrino mass determination from beta-decay of the tritium molecule
Fackler, O.; Jeziorski, B.; Kolos, W.; Szalewicz, K.; Monkhorst, H.J.; Mugge, M.
1986-03-01
Molecular final state energies and transition probabilities have been computed for beta-decay of the tritium molecule. The results are of sufficient accuracy to make a determination of the electron neutrino rest mass with an error not exceeding a few tenths of an electron volt. Effects of approximate models of tritium beta-decay on the neutrino mass determination are discussed. 14 refs., 3 figs., 1 tab.
Neutrino masses and absence of flavor changing interactions in the 2HDM from gauge principles
NASA Astrophysics Data System (ADS)
Campos, Miguel D.; Cogollo, D.; Lindner, Manfred; Melo, T.; Queiroz, Farinaldo S.; Rodejohann, Werner
2017-08-01
We propose several Two Higgs Doublet Models with the addition of an Abelian gauge group which free the usual framework from flavor changing neutral interactions and explain neutrino masses through the seesaw mechanism. We discuss the kinetic and mass-mixing gripping phenomenology which encompass several constraints coming from atomic parity violation, the muon anomalous magnetic moment, rare meson decays, Higgs physics, LEP precision data, neutrino-electron scattering, low energy accelerators and LHC probes.
Effects of Non-Standard Neutrino Emission on the Evolution of Low-Mass Stars
NASA Astrophysics Data System (ADS)
Arceo-Díaz, S.; Schrüder, K. P.; Zuber, K.
2013-04-01
In this work we use models created with the Eggleton stellar evolution code, with near solar mass and metallicity, and determine which are the parameters sensitive to an enhanced neutrino emission. We analyze the changes in stellar evolution, through alterations in the HR-Diagram and internal structure, when the existence of a non-zero magnetic dipole moment causes an increased plasmon decay rate and an enhanced neutrino cooling flux in the stellar core. We also study the apparent connection between the mass-loss rate during the RGB branch, by the Reimers mechanism, and the enhanced neutrino emission by their magnetic dipole moment.
Generalized mass ordering degeneracy in neutrino oscillation experiments
Coloma, Pilar; Schwetz, Thomas
2016-09-07
Here, we consider the impact of neutral-current (NC) nonstandard neutrino interactions (NSI) on the determination of the neutrino mass ordering. We show that in the 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 θ12 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-1 corrections from NSI to the NC electron neutrino-quark interaction and can be tested in electron neutrinomore » NC scattering experiments.« less
Grand unification and low scale implications: D₂ parity for unification and neutrino masses
Tavartkiladze, Zurab
2014-01-01
The Grand Unified SU(5)-SU(5)´ model, augmented with D₂ Parity, is considered. The latter play crucial role for phenomenology. The model has several novel properties and gives interesting phenomenological implications. The charged leptons together with right handed (or sterile) neutrinos emerge es composite states. Within considered scenario, we study the charged fermion and neutrino mass generation. Moreover, we show that the model gives successful gauge coupling unification.
Neutrino masses and mixing in A5 with flavor antisymmetry
NASA Astrophysics Data System (ADS)
Joshipura, Anjan S.; Nath, Newton
2016-08-01
We discuss the consequences of assuming that the (Majorana) neutrino mass matrix Mν and the charged lepton mass matrix Ml satisfy SνTMνSν=-Mν and Tl†MlMl†Tl=MlMl† with respect to some discrete groups Sν and Tl contained in A5. These assumptions lead to a neutrino mass spectrum with two degenerate and one massless neutrino and also constrain mixing among them. We derive possible mixing patterns following from the choices Sν=Z2 , Z2×Z2 , and Tl=Z2,Z2×Z2,Z3,Z5 as subgroups of A5. One predicts the maximal atmospheric neutrino mixing angle θ23 and μ -τ reflection symmetry in a large number of cases, but it is also possible to obtain nonmaximal values for θ23. Only the third column of the neutrino mixing matrix can be obtained at the leading order due to degeneracy in masses of two of the neutrinos. We take up a specific example within the A5 group and identify Higgs vacuum expectation values which realize the above assumptions. Nonleading terms present in this example are shown to lead to splitting among degenerate pairs and a consistent description of both neutrino masses and mixing angles.
NASA Astrophysics Data System (ADS)
Kyutoku, K.; Kiuchi, K.; Sekiguchi, Y.; Shibata, M.; Taniguchi, K.
2016-10-01
We present our recent results of numerical-relativity simulations of black hole-neutron star binary mergers incorporating approximate neutrino transport. We in particular discuss dynamical mass ejection and neutrino-driven wind.
Neutrino Mass Measurement Using a Directed Mono-Energetic Beam
NASA Astrophysics Data System (ADS)
Tsifrinovich, Vladimir; Folan, Lorcan
2015-04-01
It was shown that a directed mono-energetic neutrino beam can be generated by electron capture beta-decay in a sample with a strong hyperfine field at the radioactive nuclei. We study the conditions required to measure the neutrino rest mass using the recoil force produced by a directed neutrino beam. We consider the displacement of an atomic force microscope cantilever due to such a recoil force. We find the change in the cantilever displacement associated with the non-zero neutrino mass, as a function of nuclear half-life T1 / 2, cantilever spring constant, and temperature. We consider the opportunity to increase the sensitivity of the neutrino mass measurement using averaging of the measurement signal. We show that the optimal time for the signal accumulation is, approximately, 1.8T1 / 2. We compute the optimal signal-to-noise ratio for 119Sb nuclei decaying to 119Sn with a decrease in the nuclear spin from I = 5/2 to I = 3/2, and T1 / 2 = 38.2 hours. Finally, we present the parameters values required for detection of sub-eV neutrino rest mass, and estimate the angular distribution of neutrino radiation as a function of temperature.
Probing nonstandard neutrino cosmology with terrestrial neutrino experiments
NASA Astrophysics Data System (ADS)
Ghalsasi, Akshay; McKeen, David; Nelson, Ann E.
2017-06-01
Neutrino masses and the number of light neutrino species can be tested in a variety of laboratory experiments and also can be constrained by particle astrophysics and precision cosmology. A conflict between these various results could be an indication of new physics in the neutrino sector. In this paper, we explore the possibility for reconciliation of otherwise discrepant results in a simple model containing a light scalar field which produces mass-varying neutrinos. We extend previous work on mass-varying neutrinos to consider issues of neutrino clumping, the effects of additional contributions to neutrino mass, and reconciliation of eV mass sterile neutrinos with cosmology.
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.
Forbidden unique beta-decays and neutrino mass
NASA Astrophysics Data System (ADS)
Dvornický, Rastislav; Šimkovic, Fedor
2013-12-01
The measurement of the electron spectrum in beta-decays provides a robust direct determination of the values of neutrino masses. The planned rhenium beta-decay experiment, called the "Microcalorimeter Arrays for a Rhenium Experiment" (MARE), might probe the absolute mass scale of neutrinos with the same sensitivity as the Karlsruhe tritium neutrino mass (KATRIN) experiment, which is expected to collect data in a near future. In this contribution we discuss the spectrum of emitted electrons close to the end point in the case of the first unique forbidden beta-decay of 79Se, 107Pd and 187Re. It is found that the p3/2-wave emission dominates over the s1/2-wave. It is shown that the Kurie plot near the end point is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed beta-decay of 3H.
Massive neutrinos in the standard model and beyond
NASA Astrophysics Data System (ADS)
Thalapillil, Arun Madhav
The generation of the fermion mass hierarchy in the standard model of particle physics is a long-standing puzzle. The recent discoveries from neutrino physics suggests that the mixing in the lepton sector is large compared to the quark mixings. To understand this asymmetry between the quark and lepton mixings is an important aim for particle physics. In this regard, two promising approaches from the theoretical side are grand unified theories and family symmetries. In the first part of my thesis we try to understand certain general features of grand unified theories with Abelian family symmetries by taking the simplest SU(5) grand unified theory as a prototype. We construct an SU(5) toy model with U(1) F ⊗Z'2 ⊗Z'' 2⊗Z''' 2 family symmetry that, in a natural way, duplicates the observed mass hierarchy and mixing matrices to lowest approximation. The system for generating the mass hierarchy is through a Froggatt-Nielsen type mechanism. One idea that we use in the model is that the quark and charged lepton sectors are hierarchical with small mixing angles while the light neutrino sector is democratic with larger mixing angles. We also discuss some of the difficulties in incorporating finer details into the model without making further assumptions or adding a large scalar sector. In the second part of my thesis, the interaction of high energy neutrinos with weak gravitational fields is explored. The form of the graviton-neutrino vertex is motivated from Lorentz and gauge invariance and the non-relativistic interpretations of the neutrino gravitational form factors are obtained. We comment on the renormalization conditions, the preservation of the weak equivalence principle and the definition of the neutrino mass radius. We associate the neutrino gravitational form factors with specific angular momentum states. Based on Feynman diagrams, spin-statistics, CP invariance and symmetries of the angular momentum states in the neutrino-graviton vertex, we deduce
Nonlinear cosmological matter power spectrum with massive neutrinos: The halo model
Abazajian, Kevork; Habib, Salman; Switzer, Eric R.; Dodelson, Scott; Heitmann, Katrin
2005-02-15
Measurements of the linear power spectrum of galaxies have placed tight constraints on neutrino masses. We extend the framework of the halo model of cosmological nonlinear matter clustering to include the effect of massive neutrino infall into cold dark matter (CDM) halos. The magnitude of the effect of neutrino clustering for three degenerate mass neutrinos with m{sub {nu}{sub i}}=0.9 eV is of order {approx}1%, within the potential sensitivity of upcoming weak lensing surveys. In order to use these measurements to further constrain--or eventually detect--neutrino masses, accurate theoretical predictions of the nonlinear power spectrum in the presence of massive neutrinos will be needed, likely only possible through high-resolution multiple particle (neutrino, CDM and baryon) simulations.
The Nonlinear cosmological matter power spectrum with massive neutrinos. 1. The Halo model
Abazajian, Kevork; Switzer, Eric R.; Dodelson, Scott; Heitmann, Katrin; Habib, Salman; /Los Alamos
2004-11-01
Measurements of the linear power spectrum of galaxies have placed tight constraints on neutrino masses. We extend the framework of the halo model of cosmological nonlinear matter clustering to include the effect of massive neutrino infall into cold dark matter (CDM) halos. The magnitude of the effect of neutrino clustering for three degenerate mass neutrinos with m{sub v{sub 1}} = 0.9 eV is of order {approx}1%, within the potential sensitivity of upcoming weak lensing surveys. In order to use these measurements to further constrain--or eventually detect--neutrino masses, accurate theoretical predictions of the nonlinear power spectrum in the presence of massive neutrinos will be needed, likely only possible through high-resolution multiple particle (neutrino, CDM and baryon) simulations.
Sterile neutrinos with eV masses in cosmology — How disfavoured exactly?
Hamann, Jan; Hannestad, Steen; Raffelt, Georg G.; Wong, Yvonne Y.Y. E-mail: sth@phys.au.dk E-mail: yvonne.wong@physik.rwth-aachen.de
2011-09-01
We study cosmological models that contain sterile neutrinos with eV-range masses as suggested by reactor and short-baseline oscillation data. We confront these models with both precision cosmological data (probing the CMB decoupling epoch) and light-element abundances (probing the BBN epoch). In the minimal ΛCDM model, such sterile neutrinos are strongly disfavoured by current data because they contribute too much hot dark matter. However, if the cosmological framework is extended to include also additional relativistic degrees of freedom beyond the three standard neutrinos and the putative sterile neutrinos, then the hot dark matter constraint on the sterile states is considerably relaxed. A further improvement is achieved by allowing a dark energy equation of state parameter w < −1. While BBN strongly disfavours extra radiation beyond the assumed eV-mass sterile neutrino, this constraint can be circumvented by a small ν{sub e} degeneracy. Any model containing eV-mass sterile neutrinos implies also strong modifications of other cosmological parameters. Notably, the inferred cold dark matter density can shift up by 20–75% relative to the standard ΛCDM value.
Neutrino mass hierarchy and three-flavor spectral splits of supernova neutrinos
Dasgupta, Basudeb; Mirizzi, Alessandro; Tomas, Ricard; Tamborra, Irene
2010-05-01
It was recently realized that three-flavor effects could peculiarly modify the development of spectral splits induced by collective oscillations, for supernova neutrinos emitted during the cooling phase of a protoneutron star. We systematically explore this case, explaining how the impact of these three-flavor effects depends on the ordering of the neutrino masses. In inverted mass hierarchy, the solar mass splitting gives rise to instabilities in regions of the (anti)neutrino energy spectra that were otherwise stable under the leading two-flavor evolution governed by the atmospheric mass splitting and by the 1-3 mixing angle. As a consequence, the high-energy spectral splits found in the electron (anti)neutrino spectra disappear, and are transferred to other flavors. Imperfect adiabaticity leads to smearing of spectral swap features. In normal mass hierarchy, the three-flavor and the two-flavor instabilities act in the same region of the neutrino energy spectrum, leading to only minor departures from the two-flavor treatment.
Impact of eV-mass sterile neutrinos on neutrino-driven supernova outflows
Tamborra, Irene; Raffelt, Georg G.; Hüdepohl, Lorenz; Janka, Hans-Thomas E-mail: raffelt@mpp.mpg.de E-mail: thj@mpa-garching.mpg.de
2012-01-01
Motivated by recent hints for sterile neutrinos from the reactor anomaly, we study active-sterile conversions in a three-flavor scenario (2 active + 1 sterile families) for three different representative times during the neutrino-cooling evolution of the proto-neutron star born in an electron-capture supernova. In our ''early model'' (0.5 s post bounce), the ν{sub e}-ν{sub s} MSW effect driven by Δm{sup 2} = 2.35eV{sup 2} is dominated by ordinary matter and leads to a complete ν{sub e}-ν{sub s} swap with little or no trace of collective flavor oscillations. In our ''intermediate'' (2.9 s p.b.) and ''late models'' (6.5 s p.b.), neutrinos themselves significantly modify the ν{sub e}-ν{sub s} matter effect, and, in particular in the late model, νν refraction strongly reduces the matter effect, largely suppressing the overall ν{sub e}-ν{sub s} MSW conversion. This phenomenon has not been reported in previous studies of active-sterile supernova neutrino oscillations. We always include the feedback effect on the electron fraction Y{sub e} due to neutrino oscillations. In all examples, Y{sub e} is reduced and therefore the presence of sterile neutrinos can affect the conditions for heavy-element formation in the supernova ejecta, even if probably not enabling the r-process in the investigated outflows of an electron-capture supernova. The impact of neutrino-neutrino refraction is strong but complicated, leaving open the possibility that with a more complete treatment, or for other supernova models, active-sterile neutrino oscillations could generate conditions suitable for the r-process.
A tight SO(10) connection between leptogenesis and neutrino masses
Frigerio, Michele
2008-11-23
We discuss a source of light neutrino masses and leptogenesis in SO(10) unification theories, that was not previously recognized. It is present when the light lepton doublets belong (at least partially) to dimension-10 matter multiplets. At odds with previous leptogenesis scenarios, the CP asymmetry depends only on the low energy flavour parameters of the neutrino sector. We demonstrate that a successful generation of the baryon asymmetry of the Universe is possible.
Relic abundance of dark matter in universal extra dimension models with right-handed neutrinos
Matsumoto, Shigeki; Sato, Joe; Yamanaka, Masato; Senami, Masato
2009-04-17
Relic abundance of dark matter is investigated in the framework of universal extra dimension models with right-handed neutrinos. These models are free from the serious Kaluza-Klein (KK) graviton problem that the original universal extra dimension model possesses. The first KK particle of the right-handed neutrino is a candidate for dark matter in this framework. When ordinary neutrino masses are large enough such as the degenerate mass spectrum case, the dark matter relic abundance can change significantly. The scale of the extra dimension consistent with cosmological observations can be 500 GeV in the minimal setup of universal extra dimension models with right-handed neutrinos.
TRITIUM-β-DECAY Experiments - the Direct way to the Absolute Neutrino Mass
NASA Astrophysics Data System (ADS)
Bornschein, Lutz
2013-11-01
Tritium-β-decay experiments provide the most sensitive approach to measure the absolute neutrino mass in a model independent way. The Karlsruhe Tritium Neutrino experiment KATRIN will measure the neutrino mass scale with an expected sensitivity of 0.2 eV/c2 (90% C.L.) and so will help to clarify the roles of neutrinos in the early universe. KATRIN investigates spectroscopically the electron spectrum from tritium β-decay 3 H -> 3 {He} + {e}^ - + bar ν e close to the kinematic endpoint of 18.6 keV. It will use a windowless gaseous tritium source in combination with an electrostatic filter for energy analysis. KATRIN is currently under construction at the Karlsruhe Institute of Technology (KIT) Campus North. This proceeding will give an overview of the status of the main components of the KATRIN experiment.
Probing neutrino mass with displaced vertices at the Fermilab Tevatron
Campos, F. de; Eboli, O.J.P.; Magro, M.B.; Porod, W.; Restrepo, D.; Valle, J.W.F.
2005-04-01
Supersymmetric extensions of the standard model exhibiting bilinear R-parity violation can generate naturally the observed neutrino mass spectrum as well as mixings. One interesting feature of these scenarios is that the lightest supersymmetric particle (LSP) is unstable, with several of its decay properties predicted in terms of neutrino mixing angles. A smoking gun of this model in colliders is the presence of displaced vertices due to LSP decays in large parts of the parameter space. In this work we focus on the simplest model of this type that comes from minimal supergravity with universal R-parity conserving soft breaking of supersymmetry augmented with bilinear R-parity breaking terms at the electroweak scale (RmSUGRA). We evaluate the potential of the Fermilab Tevatron to probe the RmSUGRA parameters through the analysis of events possessing two displaced vertices stemming from LSP decays. We show that requiring two displaced vertices in the events leads to a reach in m{sub 1/2} twice the one in the usual multilepton signals in a large fraction of the parameter space.
Neutrino mass and dark energy from weak lensing.
Abazajian, Kevork N; Dodelson, Scott
2003-07-25
Weak gravitational lensing of background galaxies by intervening matter directly probes the mass distribution in the Universe. This distribution is sensitive to both the dark energy and neutrino mass. We examine the potential of lensing experiments to measure features of both simultaneously. Focusing on the radial information contained in a future deep 4000 deg(2) survey, we find that the expected (1-sigma) error on a neutrino mass is 0.1 eV, if the dark-energy parameters are allowed to vary. The constraints on dark-energy parameters are similarly restrictive, with errors on w of 0.09.
Neutrinos and the origin of fermion mass structure
Ross, Graham G.
2007-11-20
The pattern of neutrino masses and mixings is characteristically different from those observed in the quark sector. I discuss why this should be the case and what implications this has for the origin of quark and lepton masses, mixings and CP violation.
Neutrino Masses, Cosmological Bound and Four Zero Yukawa Textures
NASA Astrophysics Data System (ADS)
Adhikary, Biswajit; Ghosal, Ambar; Roy, Probir
Four zero neutrino Yukawa textures in a specified weak basis, combined with μτ symmetry and type-I seesaw, yield a highly constrained and predictive scheme. Two alternately viable 3×3 light neutrino Majorana mass matrices mνA/mνB result with inverted/normal mass ordering. Neutrino masses, Majorana in character and predicted within definite ranges with laboratory and cosmological inputs, will have their sum probed cosmologically. The rate for 0νββ decay, though generally below the reach of planned experiments, could approach it in some parameter region. Departure from μτ symmetry due to RG evolution from a high scale and consequent CP violation, with a Jarlskog invariant whose magnitude could almost reach 6×10-3, are explored.
NASA Astrophysics Data System (ADS)
Kirilova, D. P.; Chizhov, M. V.
2000-12-01
We have provided a numerical study of the influence of the resonant active-sterile neutrino oscillations νe↔ νs, on the primordial production of helium-4. The evolution of the neutrino ensembles was followed selfconsistently with the evolution of the nucleons, using exact kinetic equations for the neutrino density matrix and the nucleon number densities in momentum space, from the time of neutrino decoupling till the freeze-out of nucleons at 0.3 MeV. The exact kinetic approach enabled us to study precisely the neutrino depletion, spectrum distortion and neutrino mixing generated asymmetry due to oscillations at each momentum mode, and to prove that their effect on nucleosynthesis is considerable. We have calculated the dependence of the primordially produced helium-4 on the oscillation parameters Yp( δm2, ϑ) for the full range of mixing parameters of the model of oscillations with small mass differences δm2≤10 -7 eV 2. We have obtained iso-helium contours on the δm2- ϑ plane. Cosmological constraints on oscillation parameters, more precise than the existing ones were extracted, due to the exact kinetic approach and the proper account for the neutrino spectrum distortion and the oscillations generated asymmetry.
Neutrino mass, dark matter, and Baryon asymmetry via TeV-scale physics without fine-tuning.
Aoki, Mayumi; Kanemura, Shinya; Seto, Osamu
2009-02-06
We propose an extended version of the standard model, in which neutrino oscillation, dark matter, and the baryon asymmetry of the Universe can be simultaneously explained by the TeV-scale physics without assuming a large hierarchy among the mass scales. Tiny neutrino masses are generated at the three-loop level due to the exact Z2 symmetry, by which the stability of the dark matter candidate is guaranteed. The extra Higgs doublet is required not only for the tiny neutrino masses but also for successful electroweak baryogenesis. The model provides discriminative predictions especially in Higgs phenomenology, so that it is testable at current and future collider experiments.
Higgs portal dark matter and neutrino mass and mixing with a doubly charged scalar
NASA Astrophysics Data System (ADS)
Hierro, I. M.; King, S. F.; Rigolin, S.
2017-06-01
We consider an extension of the Standard Model involving two new scalar particles around the TeV scale: a singlet neutral scalar ϕ, 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 Z2 symmetry in the scalar sector, under which only the additional neutral scalar ϕ 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.
On Morphing Neutrinos and Why They Must Have Mass
NASA Astrophysics Data System (ADS)
Hecht, Eugene
2003-03-01
This paper explores the recently confirmed hypothesis that neutrinos have mass and that they spontaneously transform from one type to another. That immensely important discovery culminates 40 years of experimental research. After briefly discussing that work, we'll study the quantum mechanical explanation of these phenomena elaborating the concepts of particle mixing, and the oscillation of flavor types. These rather esoteric ideas lead to the prediction that morphing neutrinos must have mass, but there's a much more elegant relativistic argument that brings us to this same conclusion.
Two-loop Dirac neutrino mass and WIMP dark matter
NASA Astrophysics Data System (ADS)
Bonilla, Cesar; Ma, Ernest; Peinado, Eduardo; Valle, Jose W. F.
2016-11-01
We propose a "scotogenic" mechanism relating small neutrino mass and cosmological dark matter. Neutrinos are Dirac fermions with masses arising only in two-loop order through the sector responsible for dark matter. Two triality symmetries ensure both dark matter stability and strict lepton number conservation at higher orders. A global spontaneously broken U(1) symmetry leads to a physical Diracon that induces invisible Higgs decays which add up to the Higgs to dark matter mode. This enhances sensitivities to spin-independent WIMP dark matter search below mh / 2.
Magic neutrino mass matrix and the Bjorken Harrison Scott parameterization
NASA Astrophysics Data System (ADS)
Lam, C. S.
2006-09-01
Observed neutrino mixing can be described by a tribimaximal MNS matrix. The resulting neutrino mass matrix in the basis of a diagonal charged lepton mass matrix is both 2-3 symmetric and magic. By a magic matrix, I mean one whose row sums and column sums are all identical. I study what happens if 2-3 symmetry is broken but the magic symmetry is kept intact. In that case, the mixing matrix is parameterized by a single complex parameter Ue 3, in a form discussed recently by Bjorken, Harrison, and Scott.
Global constraints on absolute neutrino masses and their ordering
NASA Astrophysics Data System (ADS)
Capozzi, Francesco; Di Valentino, Eleonora; Lisi, Eligio; Marrone, Antonio; Melchiorri, Alessandro; Palazzo, Antonio
2017-05-01
Within the standard three-neutrino framework, the absolute neutrino masses and their ordering (either normal, NO, or inverted, IO) are currently unknown. However, the combination of current data coming from oscillation experiments, neutrinoless double beta (0 ν β β ) decay searches, and cosmological surveys, can provide interesting constraints for such unknowns in the sub-eV mass range, down to O (10-1) eV in some cases. We discuss current limits on absolute neutrino mass observables by performing a global data analysis that includes the latest results from oscillation experiments, 0 ν β β decay bounds from the KamLAND-Zen experiment, and constraints from representative combinations of Planck measurements and other cosmological data sets. In general, NO appears to be somewhat favored with respect to IO at the level of ˜2 σ , mainly by neutrino oscillation data (especially atmospheric), corroborated by cosmological data in some cases. Detailed constraints are obtained via the χ2 method, by expanding the parameter space either around separate minima in NO and IO or around the absolute minimum in any ordering. Implications for upcoming oscillation and nonoscillation neutrino experiments, including β -decay searches, are also discussed.
Dirac or Inverse Seesaw Neutrino Masses from Gauged B - L Symmetry
NASA Astrophysics Data System (ADS)
Ma, Ernest; Srivastava, Rahul
The gauged B - L symmetry is one of the simplest and well studied extension of standard model. In the conventional case, addition of three singlet right-handed neutrinos each transforming as -1 under the B - L symmetry renders it anomaly free. It is usually assumed that the B - L symmetry is spontaneously broken by a singlet scalar having two units of B - L charge, resulting in a natural implementation of Majorana seesaw mechanism for neutrinos. However, as we discuss in this proceeding, there is another simple anomaly free solution which leads to Dirac or inverse seesaw masses for neutrinos. These new possibilities are explored along with an application to neutrino mixing with S3 flavour symmetry.
Dirac or inverse seesaw neutrino masses with B – L gauge symmetry and S₃ flavor symmetry
Ma, Ernest; Srivastava, Rahul
2015-02-01
Many studies have been made on extensions of the standard model with B – L gauge symmetry. The addition of three singlet (right-handed) neutrinos renders it anomaly-free. It has always been assumed that the spontaneous breaking of B – L is accomplished by a singlet scalar field carrying two units of B – L charge. This results in a very natural implementation of the Majorana seesaw mechanism for neutrinos. However, there exists in fact another simple anomaly-free solution which allows Dirac or inverse seesaw neutrino masses. We show for the first time these new possibilities and discuss an application tomore » neutrino mixing with S₃ flavor symmetry.« less
Leptogenesis, radiative neutrino masses and inert Higgs triplet dark matter
Lu, Wen-Bin; Gu, Pei-Hong
2016-05-18
We extend the standard model by three types of inert fields including Majorana fermion singlets/triplets, real Higgs singlets/triplets and leptonic Higgs doublets. In the presence of a softly broken lepton number and an exactly conserved Z{sub 2} discrete symmetry, these inert fields together can mediate a one-loop diagram for a Majorana neutrino mass generation. The heavier inert fields can decay to realize a successful leptogenesis while the lightest inert field can provide a stable dark matter candidate. As an example, we demonstrate the leptogenesis by the inert Higgs doublet decays. We also perform a systematic study on the inert Higgs triplet dark matter scenario where the interference between the gauge and Higgs portal interactions can significantly affect the dark matter properties.
Supersymmetric inflation with constraints on superheavy neutrino masses
Lazarides, G.; Schaefer, R.K.; Shafi, Q.
1997-07-01
We consider a supersymmetric model of inflation in which the primordial density fluctuations are nearly scale invariant (spectral index n{approx}0.98) with an amplitude proportional to (M/M{sub Planck}){sup 2}, where M{approximately}10{sup 16} GeV denotes the scale of the gauge symmetry breaking associated with inflation. The 60 or so e foldings take place when all relevant scales are close to M, which helps suppress supergravity corrections. The gravitino and baryogenesis (via leptogenesis) constraints help determine the two heaviest right-handed neutrino masses to be {approx}2{times}10{sup 13} GeV and 6{times}10{sup 9} GeV. {copyright} {ital 1997} {ital The American Physical Society}
Neutrino mass and mixing: from theory to experiment
NASA Astrophysics Data System (ADS)
King, Stephen F.; Merle, Alexander; Morisi, Stefano; Shimizu, Yusuke; Tanimoto, Morimitsu
2014-04-01
The origin of fermion mass hierarchies and mixings is one of the unresolved and most difficult problems in high-energy physics. One possibility to address the flavour problems is by extending the standard model to include a family symmetry. In the recent years it has become very popular to use non-Abelian discrete flavour symmetries because of their power in the prediction of the large leptonic mixing angles relevant for neutrino oscillation experiments. Here we give an introduction to the flavour problem and to discrete groups that have been used to attempt a solution for it. We review the current status of models in light of the recent measurement of the reactor angle, and we consider different model-building directions taken. The use of the flavons or multi-Higgs scalars in model building is discussed as well as the direct versus indirect approaches. We also focus on the possibility of experimentally distinguishing flavour symmetry models by means of mixing sum rules and mass sum rules. In fact, we illustrate in this review the complete path from mathematics, via model building, to experiments, so that any reader interested in starting work in the field could use this text as a starting point in order to obtain a broad overview of the different subject areas.
NASA Astrophysics Data System (ADS)
Jinnouchi, O.; Homma, K.
1998-09-01
The unphysical result of the negative mass square of the electron neutrinos recently reported in several tritium β-decay experiments, is one of the most attractive subjects among remaining physical problems. As a possible scenario to explain the anomaly, we have assumed a reaction with relic neutrinos which are predicted by the standard big bang cosmology. If such neutrinos could exist, the interaction of the relic neutrinos with the target tritium, νe+3H-->3He+e- could be laid under the large amount of the β-decay process, 3H-->3He+e-+νē, which would cause a peak-like structure beyond the end-point in the Kurie plot. Based on the assumption, we evaluated the cross section from the event rate found in the peak by re-fitting to the 1991 data published by the Mainz Group. In this letter we will provide a scenario that can account for the evaluated cross section by introducing a spatially inhomogeneous neutrino degeneration, which would result much lower temperature than the prediction from the standard big bang cosmology.
Differential neutrino condensation onto cosmic structure
NASA Astrophysics Data System (ADS)
Yu, Hao-Ran; Emberson, J. D.; Inman, Derek; Zhang, Tong-Jie; Pen, Ue-Li; Harnois-Déraps, Joachim; Yuan, Shuo; Teng, Huan-Yu; Zhu, Hong-Ming; Chen, Xuelei; Xing, Zhi-Zhong; Du, Yunfei; Zhang, Lilun; Lu, Yutong; Liao, Xiangke
2017-07-01
Astrophysical techniques have pioneered the discovery of neutrino mass properties. Currently, the known neutrino effects on the large-scale structure of the Universe are all global, and neutrino masses are constrained by attempting to disentangle the small neutrino contribution from the sum of all matter using precise theoretical models. We investigate an alternative approach: to detect the difference between the neutrinos and that of dark matter and baryons. Here, by using one of the largest N-body simulations yet, we discover the differential neutrino condensation effect: in regions of the Universe with different neutrino relative abundance (the local ratio of neutrino to cold dark matter density), halo properties are different and neutrino mass can be inferred. In 'neutrino-rich' regions, more neutrinos can be captured by massive halos compared with 'neutrino-poor' regions. This effect differentially skews the halo mass function and opens up the path to independent measurements of neutrino mass in current or future galaxy surveys.
Proton hexality from an anomalous flavor U(1) and neutrino masses: Linking to the string scale
NASA Astrophysics Data System (ADS)
Dreiner, Herbi K.; Luhn, Christoph; Murayama, Hitoshi; Thormeier, Marc
2008-05-01
We devise minimalistic gauged U(1 Froggatt-Nielsen models which at low-energy give rise to the recently suggested discrete gauge Z-symmetry, proton hexality, thus stabilizing the proton. Assuming three generations of right-handed neutrinos, with the proper choice of X-charges, we obtain viable neutrino masses. Furthermore, we find scenarios such that no X-charged hidden sector superfields are needed, which from a bottom-up perspective allows the calculation of g, g and G's Kač-Moody levels. The only mass scale apart from M is m.
Neutrino mass limits: Robust information from the power spectrum of galaxy surveys
NASA Astrophysics Data System (ADS)
Cuesta, Antonio J.; Niro, Viviana; Verde, Licia
2016-09-01
We present cosmological upper limits on the sum of active neutrino masses using large-scale power spectrum data from the WiggleZ Dark Energy Survey and from the Sloan Digital Sky Survey - Data Release 7 (SDSS-DR7) sample of Luminous Red Galaxies (LRG). Combining measurements on the Cosmic Microwave Background temperature and polarisation anisotropies by the Planck satellite together with WiggleZ power spectrum results in a neutrino mass bound of 0.37 eV at 95% C.L., while replacing WiggleZ by the SDSS-DR7 LRG power spectrum, the 95% C.L. bound on the sum of neutrino masses is 0.38 eV. Adding Baryon Acoustic Oscillation (BAO) distance scale measurements, the neutrino mass upper limits greatly improve, since BAO data break degeneracies in parameter space. Within a ΛCDM model, we find an upper limit of 0.13 eV (0.14 eV) at 95% C.L., when using SDSS-DR7 LRG (WiggleZ) together with BAO and Planck. The addition of BAO data makes the neutrino mass upper limit robust, showing only a weak dependence on the power spectrum used. We also quantify the dependence of neutrino mass limit reported here on the CMB lensing information. The tighter upper limit (0.13 eV) obtained with SDSS-DR7 LRG is very close to that recently obtained using Lyman-alpha clustering data, yet uses a completely different probe and redshift range, further supporting the robustness of the constraint. This constraint puts under some pressure the inverted mass hierarchy and favours the normal hierarchy.
Neutrino mass constraint from CMB, BAO and SN
Ichikawa, Kazuhide
2007-11-20
We show that the cosmic microwave background (CMB) data of WMAP can give subelectronvolt limit on the neutrino mass. We investigate how much we can make it more stringent by using 'standard ruler' measurements such as baryon acoustic oscillation (BAO) and type Ia supernovae (SN)
NASA Technical Reports Server (NTRS)
Loredo, Thomas J.; Lamb, Don Q.
1989-01-01
Data on neutrinos from SN 1987A are compared here with parameterized models of the neutrino emission using a consistent and straightforward statistical methodology. The empirically measured detector background spectra are included in the analysis, and the data are compared with a much wider variety of neutrino emission models than was explored previously. It is shown that the inferred neutrino emission model parameters are strongly correlated. The analysis confirms that simple models of the neutrino cooling of the nascent neutron star formed by the SN adequately explain the data. The inferred radius and binding energy of the neutron star are in excellent agreement with model calculations based on a wide range of equations of state. The results also raise the upper limit of the electron antineutrino rest mass to roughly 25 eV at the 95 percent confidence level, roughly 1.5-5 times higher than found previously.
NASA Technical Reports Server (NTRS)
Loredo, Thomas J.; Lamb, Don Q.
1989-01-01
Data on neutrinos from SN 1987A are compared here with parameterized models of the neutrino emission using a consistent and straightforward statistical methodology. The empirically measured detector background spectra are included in the analysis, and the data are compared with a much wider variety of neutrino emission models than was explored previously. It is shown that the inferred neutrino emission model parameters are strongly correlated. The analysis confirms that simple models of the neutrino cooling of the nascent neutron star formed by the SN adequately explain the data. The inferred radius and binding energy of the neutron star are in excellent agreement with model calculations based on a wide range of equations of state. The results also raise the upper limit of the electron antineutrino rest mass to roughly 25 eV at the 95 percent confidence level, roughly 1.5-5 times higher than found previously.
Avignone, F.T. III; Brodzinski, R.L.; Brown, D.P.; Evans, J.C. Jr.; Hensley, W.K.; Reeves, J.H.; Wogman, N.A.
1983-03-07
A continuing search for the no-neutrino mode of the double beta decay of /sup 76/Ge has resulted in a new lower limit T/sub 1/2//sup 0nu/ > or =1.7 x 10/sup 22/ yr. This value corresponds to a 90% confidence level determined with a maximum-likelihood analysis of the energy interval 2041 +- 2 keV. Combined with recent shell-model calculations, the data imply m/sub ..nu../< or =10 eV and a limit on lepton nonconservation Vertical BaretaVertical Bar< or =2.4 x 10/sup -5/. In the context of the shell model, the data imply that the electron neutrino is not a Majorana mass eigenstate.
Mass varying neutrinos, quintessence, and the accelerating expansion of the Universe
Chitov, Gennady Y.; August, Tyler; Natarajan, Aravind; Kahniashvili, Tina
2011-02-15
We analyze the mass varying neutrino scenario. We consider a minimal model of massless Dirac fermions coupled to a scalar field, mainly in the framework of finite-temperature quantum field theory. We demonstrate that the mass equation we find has nontrivial solutions only for special classes of potentials, and only within certain temperature intervals. We give most of our results for the Ratra-Peebles dark energy (DE) potential. The thermal (temporal) evolution of the model is analyzed. Following the time arrow, the stable, metastable, and unstable phases are predicted. The model predicts that the present Universe is below its critical temperature and accelerates. At the critical point, the Universe undergoes a first-order phase transition from the (meta)stable oscillatory regime to the unstable rolling regime of the DE field. This conclusion agrees with the original idea of quintessence as a force making the Universe roll towards its true vacuum with a zero {Lambda} term. The present mass varying neutrino scenario is free from the coincidence problem, since both the DE density and the neutrino mass are determined by the scale M of the potential. Choosing M{approx}10{sup -3} eV to match the present DE density, we can obtain the present neutrino mass in the range m{approx}10{sup -2}-1 eV and consistent estimates for other parameters of the Universe.
Mass hierarchy determination via future atmospheric neutrino detectors
NASA Astrophysics Data System (ADS)
Gandhi, Raj; Ghoshal, Pomita; Goswami, Srubabati; Mehta, Poonam; Uma Sankar, S.; Shalgar, Shashank
2007-10-01
We study the problem of determination of the sign of Δm312, or the neutrino mass hierarchy, through observations of atmospheric neutrinos in future detectors. We consider two proposed detector types: (a) Megaton sized water C̆erenkov detectors, which can measure the event rates of νμ+ν¯μ and νe+ν¯e and (b) 100 kton sized magnetized iron detectors, which can measure the event rates of νμ and ν¯μ. For energies and path lengths relevant to atmospheric neutrinos, these rates obtain significant matter contributions from Pμe, Pμμ and Pee, leading to an appreciable sensitivity to the hierarchy. We do a binned χ2 analysis of simulated data in these two types of detectors which includes the effect of smearing in neutrino energy and direction and incorporates detector efficiencies and relevant statistical, theoretical and systematic errors. We also marginalize the χ2 over the allowed ranges of neutrino parameters in order to accurately account for their uncertainties. Finally, we compare the performance of both types of detectors vis a vis the hierarchy determination.
Phenomenology of "bimaximal + Democratic" Type Neutrino Mass Matrix
NASA Astrophysics Data System (ADS)
Ghosal, Ambar; Majumdar, Debasish
We demonstrate that "Bimaximal + Democratic" type neutrino mass matrix can accommodate the deviation of θ⊙ from its maximal value along with the other present-day neutrino experimental results, namely, atmospheric, CHOOZ, neutrinoless double beta decay (ββ0ν) and result obtained from WMAP experiment. We define a function χp in terms of solar and atmospheric neutrino mass squared differences and solar neutrino mixing angle (obtained from different experiments and our proposed texture). The masses and mixing angles are expressed in terms of three parameters in our proposed texture. The allowed region of the texture parameters is obtained through minimization of the above function. The proposed texture crucially depends on the value of the experimental results of ββ0ν experiment among all other above-mentioned experiments. If, in future, ββ0ν experiments, namely, MOON, EXO, GENIUS shift the lower bound on
Forbidden unique beta-decays and neutrino mass
Dvornický, Rastislav; Šimkovic, Fedor
2013-12-30
The measurement of the electron spectrum in beta-decays provides a robust direct determination of the values of neutrino masses. The planned rhenium beta-decay experiment, called the “Microcalorimeter Arrays for a Rhenium Experiment” (MARE), might probe the absolute mass scale of neutrinos with the same sensitivity as the Karlsruhe tritium neutrino mass (KATRIN) experiment, which is expected to collect data in a near future. In this contribution we discuss the spectrum of emitted electrons close to the end point in the case of the first unique forbidden beta-decay of {sup 79}Se, {sup 107}Pd and {sup 187}Re. It is found that the p{sub 3/2}-wave emission dominates over the s{sub 1/2}-wave. It is shown that the Kurie plot near the end point is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed beta-decay of {sup 3}H.
TRIMS: Validating T2 Molecular Effects for Neutrino Mass Experiments
NASA Astrophysics Data System (ADS)
Lin, Ying-Ting; Bodine, Laura; Enomoto, Sanshiro; Kallander, Matthew; Machado, Eric; Parno, Diana; Robertson, Hamish; Trims Collaboration
2017-01-01
The upcoming KATRIN and Project 8 experiments will measure the model-independent effective neutrino mass through the kinematics near the endpoint of tritium beta-decay. A critical systematic, however, is the understanding of the molecular final-state distribution populated by tritium decay. In fact, the current theory incorporated in the KATRIN analysis framework predicts an observable that disagrees with an experimental result from the 1950s. The Tritium Recoil-Ion Mass Spectrometer (TRIMS) experiment will reexamine branching ratio of the molecular tritium (T2) beta decay to the bound state (3HeT+). TRIMS consists of a magnet-guided time-of-flight mass spectrometer with a detector located on each end. By measuring the kinetic energy and time-of-flight difference of the ions and beta particles reaching the detectors, we will be able to distinguish molecular ions from atomic ones and hence derive the ratio in question.We will give an update on simulation software, analysis tools, and the apparatus, including early commissioning results. U.S. Department of Energy Office of Science, Office of Nuclear Physics, Award Number DE-FG02-97ER41020.
NASA Astrophysics Data System (ADS)
Gu, Pei-Hong; Ma, Ernest; Sarkar, Utpal
2016-12-01
The scotogenic mechanism for radiative neutrino mass is generalized to include neutron-antineutron oscillation as well as proton decay. Dark matter is stabilized by extending the notion of lepton parity to matter parity. Leptogenesis is also a possible byproduct. This framework unifies the description of all these important topics in physics beyond the standard model of particle interactions.
Dark matter physics in neutrino specific two Higgs doublet model
NASA Astrophysics Data System (ADS)
Baek, Seungwon; Nomura, Takaaki
2017-03-01
Although the seesaw mechanism is a natural explanation for the small neutrino masses, there are cases when the Majorana mass terms for the right-handed neutrinos are not allowed due to symmetry. In that case, if neutrino-specific Higgs doublet is introduced, neutrinos become Dirac particles and their small masses can be explained by its small VEV. We show that the same symmetry, which we assume a global U(1) X , can also be used to explain the stability of dark matter. In our model, a new singlet scalar breaks the global symmetry spontaneously down to a discrete Z 2 symmetry. The dark matter particle, lightest Z 2-odd fermion, is stabilized. We discuss the phenomenology of dark matter: relic density, direct detection, and indirect detection. We find that the relic density can be explained by a novel Goldstone boson channel or by resonance channel. In the most region of parameter space considered, the direct detections is suppressed well below the current experimental bound. Our model can be further tested in indirect detection experiments such as FermiLAT gamma ray searches or neutrinoless double beta decay experiments.
Revisiting large neutrino magnetic moments
NASA Astrophysics Data System (ADS)
Lindner, Manfred; Radovčić, Branimir; Welter, Johannes
2017-07-01
Current experimental sensitivity on neutrino magnetic moments is many orders of magnitude above the Standard Model prediction. A potential measurement of next-generation experiments would therefore strongly request new physics beyond the Standard Model. However, large neutrino magnetic moments generically tend to induce large corrections to the neutrino masses and lead to fine-tuning. We show that in a model where neutrino masses are proportional to neutrino magnetic moments. We revisit, discuss and propose mechanisms that still provide theoretical consistent explanations for a potential measurement of large neutrino magnetic moments. We find only two viable mechanisms to realize large transition magnetic moments for Majorana neutrinos only.
Phenomenology of the minimal B-L extension of the standard model: Z{sup '} and neutrinos
Basso, Lorenzo; Belyaev, Alexander; Moretti, Stefano; Shepherd-Themistocleous, Claire H.
2009-09-01
We present the Large Hadron Collider (LHC) discovery potential in the Z{sup '} and heavy neutrino sectors of a U(1){sub B-L} enlarged standard model also encompassing 3 heavy Majorana neutrinos. This model exhibits novel signatures at the LHC, the most interesting arising from a Z{sup '} decay chain involving heavy neutrinos, eventually decaying into leptons and jets. In particular, this signature allows one to measure the Z{sup '} and heavy neutrino masses involved. In addition, over a large region of the parameter space, the heavy neutrinos are rather long-lived particles producing distinctive displaced vertices that can be seen in the detectors. Lastly, the simultaneous measurement of both the heavy neutrino mass and decay length enables an estimate of the absolute mass of the parent light neutrino.
Textures with two traceless submatrices of the neutrino mass matrix
Alhendi, H. A.; Mudlej, A. A.; Lashin, E. I.
2008-01-01
We propose a new texture for the light neutrino mass matrix. The proposal is based upon imposing a zero-trace condition on the two-by-two submatrices of the complex symmetric Majorana mass matrix in the flavor basis where the charged lepton mass matrix is diagonal. Restricting the mass matrix to have two traceless submatrices may be found sufficient to describe the current data. Eight out of 15 independent possible cases are found to be compatible with current data. Numerical and some approximate analytical results are presented.
Effect of neutrino rest mass on ionization equilibrium freeze-out
Grohs, Evan Bradley; Fuller, George M.; Kishimoto, Chad T.; ...
2015-12-23
We show how small neutrino rest masses can increase the expansion rate near the photon decoupling epoch in the early Universe, causing an earlier, higher temperature freeze-out for ionization equilibrium compared to the massless neutrino case. This yields a larger free-electron fraction, thereby affecting the photon diffusion length differently than the sound horizon at photon decoupling. This neutrino-mass and recombination effect depends strongly on the neutrino rest masses. Ultimately, though below current sensitivity, this effect could be probed by next-generation cosmic microwave background experiments, giving another observational handle on neutrino rest mass.
Effect of neutrino rest mass on ionization equilibrium freeze-out
NASA Astrophysics Data System (ADS)
Grohs, E.; Fuller, G. M.; Kishimoto, C. T.; Paris, M. W.
2015-12-01
We show how small neutrino rest masses can increase the expansion rate near the photon decoupling epoch in the early Universe, causing an earlier, higher temperature freeze-out for ionization equilibrium compared to the massless neutrino case. This yields a larger free-electron fraction, thereby affecting the photon diffusion length differently than the sound horizon at photon decoupling. This neutrino-mass and recombination effect depends strongly on the neutrino rest masses. Though below current sensitivity, this effect could be probed by next-generation cosmic microwave background experiments, giving another observational handle on neutrino rest mass.
Effect of neutrino rest mass on ionization equilibrium freeze-out
Grohs, Evan Bradley; Fuller, George M.; Kishimoto, Chad T.; Paris, Mark W.
2015-12-23
We show how small neutrino rest masses can increase the expansion rate near the photon decoupling epoch in the early Universe, causing an earlier, higher temperature freeze-out for ionization equilibrium compared to the massless neutrino case. This yields a larger free-electron fraction, thereby affecting the photon diffusion length differently than the sound horizon at photon decoupling. This neutrino-mass and recombination effect depends strongly on the neutrino rest masses. Ultimately, though below current sensitivity, this effect could be probed by next-generation cosmic microwave background experiments, giving another observational handle on neutrino rest mass.
Computation of neutrino masses in R-parity violating supersymmetry: SOFTSUSY3.2
NASA Astrophysics Data System (ADS)
Allanach, B. C.; Kom, C. H.; Hanussek, M.
2012-03-01
The program SOFTSUSY can calculate tree-level neutrino masses in the R-parity violating minimal supersymmetric standard model (MSSM) with real couplings. At tree-level, only one neutrino acquires a mass, in contradiction with neutrino oscillation data. Here, we describe an extension to the SOFTSUSY program which includes one-loop R-parity violating effects' contributions to neutrino masses and mixing. Including the one-loop effects refines the radiative electroweak symmetry breaking calculation, and may result in up to three massive, mixed neutrinos. This paper serves as a manual to the neutrino mass prediction mode of the program, detailing the approximations and conventions used. Program summaryProgram title: SOFTSUSY Catalogue identifier: ADPM_v3_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADPM_v3_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License version 3 No. of lines in distributed program, including test data, etc.: 93 291 No. of bytes in distributed program, including test data, etc.: 1 288 618 Distribution format: tar.gz Programming language: C++, Fortran Computer: Personal computer Operating system: Tested on Linux 4.x Word size: 32 bits Classification: 11.1, 11.6 Catalogue identifier of previous version: ADPM_v2_0 Journal reference of previous version: Comput. Phys. Comm. 181 (2010) 232 Does the new version supersede the previous version?: Yes Nature of problem: Calculation of neutrino masses and the neutrino mixing matrix at one-loop level in the R-parity violating minimal supersymmetric standard model. The solution to the renormalisation group equations must be consistent with a high or weak-scale boundary condition on supersymmetry breaking parameters and R-parity violating parameters, as well as a weak-scale boundary condition on gauge couplings, Yukawa couplings and the Higgs potential parameters. Solution method: Nested iterative algorithm
Cosmological axion and neutrino mass constraints from Planck 2015 temperature and polarization data
NASA Astrophysics Data System (ADS)
Di Valentino, Eleonora; Giusarma, Elena; Lattanzi, Massimiliano; Mena, Olga; Melchiorri, Alessandro; Silk, Joseph
2016-01-01
Axions currently provide the most compelling solution to the strong CP problem. These particles may be copiously produced in the early universe, including via thermal processes. Therefore, relic axions constitute a hot dark matter component and their masses are strongly degenerate with those of the three active neutrinos, as they leave identical signatures in the different cosmological observables. In addition, thermal axions, while still relativistic states, also contribute to the relativistic degrees of freedom, parameterized via Neff. We present the cosmological bounds on the relic axion and neutrino masses, exploiting the full Planck mission data, which include polarization measurements. In the mixed hot dark matter scenario explored here, we find the tightest and more robust constraint to date on the sum of the three active neutrino masses, ∑mν < 0.136 eV at 95% CL, as it is obtained in the very well-known linear perturbation regime. The Planck Sunyaev-Zeldovich cluster number count data further tightens this bound, providing a 95% CL upper limit of ∑mν < 0.126 eV in this very same mixed hot dark matter model, a value which is very close to the expectations in the inverted hierarchical neutrino mass scenario. Using this same combination of data sets we find the most stringent bound to date on the thermal axion mass, ma < 0.529 eV at 95% CL.
Minakata, H.; Nunokawa, H.; Parke, S.J.; Zukanovich Funchal, R.; /Sao Paulo U.
2006-07-01
Recently a new method for determining the neutrino mass hierarchy by comparing the effective values of the atmospheric {Delta}m{sup 2} measured in the electron neutrino disappearance channel, {Delta}m{sup 2}(ee), with the one measured in the muon neutrino disappearance channel, {Delta}m{sup 2}({mu}{mu}), was proposed. If {Delta}m{sup 2}(ee) is larger (smaller) than {Delta}m{sup 2} ({mu}{mu}) the hierarchy is of the normal (inverted) type. We re-examine this proposition in the light of two very high precision measurements: {Delta}m{sup 2}({mu}{mu}) that may be accomplished by the phase II of the Tokai-to-Kamioka (T2K) experiment, for example, and {Delta}m{sup 2}(ee) that can be envisaged using the novel Moessbauer enhanced resonant {bar {nu}}{sub e} absorption technique. Under optimistic assumptions for the systematic uncertainties of both measurements, we estimate the parameter region of ({theta}{sub 13}, {delta}) in which the mass hierarchy can be determined. If {theta}{sub 13} is relatively large, sin{sup 2} 2{theta}{sub 13} {approx}> 0.05, and both of {Delta}m{sup 2}(ee) and {Delta}m{sup 2}({mu}{mu}) can be measured with the precision of {approx} 0.5 % it is possible to determine the neutrino mass hierarchy at > 95% CL for 0.3{pi} {approx}< {delta} {approx}< 1.7 {pi} for the current best fit values of all the other oscillation parameters.
Solar models, neutrino experiments, and helioseismology
NASA Technical Reports Server (NTRS)
Bahcall, John N.; Ulrich, Roger K.
1988-01-01
The event rates and their recognized uncertainties are calculated for 11 solar neutrino experiments using accurate solar models. These models are also used to evaluate the frequency spectrum of the p and g oscillations modes of the sun. It is shown that the discrepancy between the predicted and observed event rates in the Cl-37 and Kamiokande II experiments cannot be explained by a 'likely' fluctuation in input parameters with the best estimates and uncertainties given in the present study. It is suggested that, whatever the correct solution to the solar neutrino problem, it is unlikely to be a 'trival' error.
Seesaw model and two zero flavor neutrino texture
NASA Astrophysics Data System (ADS)
Kitabayashi, Teruyuki; Yasuè, Masaki
2017-03-01
In the two zero flavor neutrino mass matrix scheme with nonvanishing Majorana effective mass Mee for the neutrinoless double beta decay, four textures are compatible with observed data. We obtain the complete list of the possible textures of four zero Dirac neutrino mass matrix mD in the seesaw mechanism providing these four flavor neutrino textures. Explicit analytical analysis of mD turns out to provide the relation of mD ∝Mee.
NASA Astrophysics Data System (ADS)
Mathews, G. J.; Kajino, T.; Aoki, W.; Fujiya, W.; Pitts, J. B.
2012-05-01
There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced ν-process B11 and or Li7 encapsulated in the grains. The synthesis of B11 and Li7 via neutrino-induced nucleon emission (the ν process) in supernovas is sensitive to the neutrino mass hierarchy for finite sin22θ13>0.001. This sensitivity arises because, when there is 13 mixing, the average electron neutrino energy for charged-current neutrino reactions is larger for a normal mass hierarchy than for an inverted hierarchy. Recent constraints on θ13 from the Daya Bay, Double Chooz, MINOS, RENO, and T2K collaborations all suggest that indeed sin22θ13>0.001. We examine the possible implications of these new results based upon a Bayesian analysis of the uncertainties in the measured meteoritic material and the associated supernova nucleosynthesis models. We show that although the uncertainties are large, they hint at a marginal preference for an inverted neutrino mass hierarchy. We discuss the possibility that an analysis of more X grains enriched in Li and B along with a better understanding of the relevant stellar nuclear and neutrino reactions could eventually reveal the neutrino mass hierarchy.
Multinucleon Ejection Model for Two Body Current Neutrino Interactions
Sobczyk, Jan T.; /Fermilab
2012-06-01
A model is proposed to describe nucleons ejected from a nucleus as a result of two-body-current neutrino interactions. The model can be easily implemented in Monte Carlo neutrino event generators. Various possibilities to measure the two-body-current contribution are discussed. The model can help identify genuine charge current quasielastic events and allow for a better determination of the systematic error on neutrino energy reconstruction in neutrino oscillation experiments.
Novel Ideas for Neutrino Beams
Peach, Ken
2007-04-23
Recent developments in neutrino physics, primarily the demonstration of neutrino oscillations in both atmospheric neutrinos and solar neutrinos, provide the first conclusive evidence for physics beyond the Standard Model of particle physics. The simplest phenomenology of neutrino oscillations, for three generations of neutrino, requires six parameters - two squared mass differences, 3 mixing angles and a complex phase that could, if not 0 or {pi}, contribute to the otherwise unexplained baryon asymmetry observed in the universe. Exploring the neutrino sector will require very intense beams of neutrinos, and will need novel solutions.
Lai, Kwang-Chang; Lee, Fei-Fan; Lee, Feng-Shiuh; Lin, Guey-Lin; Liu, Tsung-Che; Yang, Yi
2016-07-22
The neutrino mass hierarchy is one of the neutrino fundamental properties yet to be determined. We introduce a method to determine neutrino mass hierarchy by comparing the interaction rate of neutral current (NC) interactions, ν(ν-bar)+p→ν(ν-bar)+p, and inverse beta decays (IBD), ν-bar{sub e}+p→n+e{sup +}, of supernova neutrinos in scintillation detectors. Neutrino flavor conversions inside the supernova are sensitive to neutrino mass hierarchy. Due to Mikheyev-Smirnov-Wolfenstein effects, the full swapping of ν-bar{sub e} flux with the ν-bar{sub x} (x=μ, τ) one occurs in the inverted hierarchy, while such a swapping does not occur in the normal hierarchy. As a result, more high energy IBD events occur in the detector for the inverted hierarchy than the high energy IBD events in the normal hierarchy. By comparing IBD interaction rate with the mass hierarchy independent NC interaction rate, one can determine the neutrino mass hierarchy.
Dark matter, {mu} problem, and neutrino mass with gauged R symmetry
Choi, Ki-Young; Chun, Eung Jin; Lee, Hyun Min
2010-11-15
We show that the {mu} problem and the strong CP problem can be resolved in the context of the gauged U(1){sub R} symmetry, realizing an automatic Peccei-Quinn symmetry. In this scheme, right-handed neutrinos can be introduced to explain small Majorana or Dirac neutrino mass. The U(1){sub R} D-term mediated supersymmetry (SUSY) breaking, called the U(1){sub R} mediation, gives rise to a specific form of the flavor-conserving superpartner masses. For the given solution to the {mu} problem, electroweak symmetry breaking condition requires the superpartners of the standard model at low energy to be much heavier than the gravitino. Thus, the dark matter candidate can be either gravitino or right-handed sneutrino. In the Majorana neutrino case, only gravitino is a natural dark matter candidate. On the other hand, in the Dirac neutrino case, the right-handed sneutrino can be also a dark matter candidate as it gets mass only from SUSY breaking. We discuss the non-thermal production of our dark matter candidates from the late decay of stau and find that the constraints from the big bang nucleosynthesis can be evaded for a TeV-scale stau mass.
Peccei-Quinn symmetry, dark matter, and neutrino mass
Ma, Ernest
2014-06-24
It is pointed out that a residual Z{sub 2} symmetry of the usual anomalous Peccei-Quinn U(1){sub PQ} symmetry (which solves the strong CP problem) may be used for an absolutely stable heavy dark-matter particle in addition to the long-lived axion. The same Z{sub 2} symmetry may also be used to generate radiative neutrino mass.
High-scale leptogenesis with three-loop neutrino mass generation and dark matter
NASA Astrophysics Data System (ADS)
Gu, Pei-Hong
2017-04-01
We demonstrate a common origin for high-scale leptogenesis and three-loop neutrino mass generation. Specifically we extend the standard model by two real singlet scalars, two singly charged scalars carrying different quantum numbers under certain global symmetry and two or more singlet fermions with Majorana masses. This global symmetry is only allowed to be softly or spontaneously broken. Our model also respects an exactly conserved Z 2 discrete symmetry. Through the real scalar decays and then the charged scalar decays, we can obtain a lepton asymmetry stored in the standard model leptons. This lepton asymmetry can be partially converted to a baryon asymmetry by the sphaleron processes. The interactions for this leptogenesis can also result in a three-loop diagram to generate the neutrino masses. The lightest singlet fermion can keep stable to serve as a dark matter particle.
Neutrino mass, electron capture, and the shake-off contributions
NASA Astrophysics Data System (ADS)
Faessler, Amand; Gastaldo, Loredana; Šimkovic, Fedor
2017-04-01
Electron capture can determine the electron neutrino mass, while the β decay of tritium measures the electron antineutrino mass and the neutrinoless double β decay observes the Majorana neutrino mass. In electron capture, e.g., Ho16367+e-→Dy16366*+νe , one can determine the electron neutrino mass from the upper end of the decay spectrum of the excited Dy, which is given by the Q value minus the neutrino mass. The excitation of Dy is described by one, two, and even three hole excitations limited by the Q value. These states decay by x-ray and Auger electron emissions. The total decay energy is measured in a bolometer. These excitations have been studied by Robertson and by Faessler et al. In addition the daughter atom Dy can also be excited by moving in the capture process one (or more) electrons into the continuum. The escape of these continuum electrons is automatically included in the experimental bolometer spectrum. Recently a method developed by Intemann and Pollock was used by DeRujula and Lusignoli for a rough estimate of this shake-off process for "s " wave electrons in capture on 163Ho. The purpose of the present work is to give a more reliable description of "s " wave shake-off in electron capture on holmium. One uses the sudden approximation to calculate the spectrum of the decay of Dy16366* after electron capture on Ho16367. For that one needs very accurate atomic wave functions of Ho in its ground state and excited atomic wave functions of Dy including a description of the continuum electrons. DeRujula and Lusignoli use screened nonrelativistic Coulomb wave functions for the Ho electrons 3 s and 4 s and calculate the Dy* states by first-order perturbation theory based on Ho. In the present approach the wave functions of Ho and Dy* are determined self-consistently with the antisymmetrized relativistic Dirac-Hartree-Fock approach. The relativistic continuum electron wave functions for the ionized Dy* are obtained in the corresponding self
Fourth standard model family neutrino at future linear colliders
Ciftci, A.K.; Ciftci, R.; Sultansoy, S.
2005-09-01
It is known that flavor democracy favors the existence of the fourth standard model (SM) family. In order to give nonzero masses for the first three-family fermions flavor democracy has to be slightly broken. A parametrization for democracy breaking, which gives the correct values for fundamental fermion masses and, at the same time, predicts quark and lepton Cabibbo-Kobayashi-Maskawa (CKM) matrices in a good agreement with the experimental data, is proposed. The pair productions of the fourth SM family Dirac ({nu}{sub 4}) and Majorana (N{sub 1}) neutrinos at future linear colliders with {radical}(s)=500 GeV, 1 TeV, and 3 TeV are considered. The cross section for the process e{sup +}e{sup -}{yields}{nu}{sub 4}{nu}{sub 4}(N{sub 1}N{sub 1}) and the branching ratios for possible decay modes of the both neutrinos are determined. The decays of the fourth family neutrinos into muon channels ({nu}{sub 4}(N{sub 1}){yields}{mu}{sup {+-}}W{sup {+-}}) provide cleanest signature at e{sup +}e{sup -} colliders. Meanwhile, in our parametrization this channel is dominant. W bosons produced in decays of the fourth family neutrinos will be seen in detector as either di-jets or isolated leptons. As an example, we consider the production of 200 GeV mass fourth family neutrinos at {radical}(s)=500 GeV linear colliders by taking into account di-muon plus four jet events as signatures.
Radiative neutrino model with S U (2 )L triplet fields
NASA Astrophysics Data System (ADS)
Nomura, Takaaki; Okada, Hiroshi; Orikasa, Yuta
2016-12-01
We propose a loop-induced neutrino mass model, in which we introduce several exotic fermions and bosons with an S U (2 )L multiplet, and discuss various phenomenologies such as lepton flavor violations, the muon anomalous magnetic moment, nonstandard interacting neutrinoless double beta decay, the relic density of dark matter, and the possibility of the spin-independent direct detection searches, imposing the constraints of oblique parameters. And we show a benchmark point to satisfy all the constraints and discuss our predictions.
Relic abundance of dark matter in universal extra dimension models with right-handed neutrinos
Matsumoto, Shigeki; Sato, Joe; Yamanaka, Masato; Senami, Masato
2007-08-15
Relic abundance of dark matter is investigated in the framework of universal extra dimension models with right-handed neutrinos. These models are free from the serious Kaluza-Klein (KK) graviton problem that the original universal extra dimension model has. The first KK particle of the right-handed neutrino is a candidate for dark matter in this framework, and its relic abundance is determined by three processes, (1) the decay of the KK photon into the first KK right-handed neutrino in the late universe, (2) production of the first KK right-handed neutrino from the thermal bath in the early universe, and (3) the decay of higher KK right-handed neutrinos into the first KK right-handed neutrino in the late universe. When ordinary neutrino masses are large enough such as the degenerate mass spectrum case, the last process contributes to the abundance significantly, even if the reheating temperature is low. The scale of the extra dimension consistent with cosmological observations can be 500 GeV in the minimal setup of universal extra dimension models with right-handed neutrinos.
NASA Astrophysics Data System (ADS)
Murthy, P. V. R.
The astrophysics and high energy physics of neutrinos are discussed. The former includes the topics of solar neutrinos, gravitational stellar collapses, neutrinos at high and superhigh energies, and DUMAND and related topics. Experimental results from the Homestake mine chlorine-37 experiment on solar neutrinos are shown. The solar neutrino puzzle is assessed, the economic aspects of DUMAND are discussed, and expectations for related projects are examined. For high energy physics, the discussion includes DUMAND and related projects, neutrino oscillations, the resolution of the puzzles of the measurement of the stopping muon flux and of the cosmic ray event time intervals, and the proton decay experiments.
Physical effects involved in the measurements of neutrino masses with future cosmological data
NASA Astrophysics Data System (ADS)
Archidiacono, Maria; Brinckmann, Thejs; Lesgourgues, Julien; Poulin, Vivian
2017-02-01
Future Cosmic Microwave Background experiments together with upcoming galaxy and 21-cm surveys will provide extremely accurate measurements of different cosmological observables located at different epochs of the cosmic history. The new data will be able to constrain the neutrino mass sum with the best precision ever. In order to exploit the complementarity of the different redshift probes, a deep understanding of the physical effects driving the impact of massive neutrinos on CMB and large scale structures is required. The goal of this work is to describe these effects, assuming a summed neutrino mass close to its minimum allowed value. We find that parameter degeneracies can be removed by appropriate combinations, leading to robust and model independent constraints. A joint forecast of the sensitivity of Euclid and DESI surveys together with a CORE-like CMB experiment leads to a 1σ uncertainty of 14 meV on the summed neutrino mass. Finally the degeneracy between Mν and the optical depth at reionization τreio, originating in the combination of CMB and low redshift galaxy probes, might be broken by future 21-cm surveys, thus further decreasing the uncertainty on Mν. For instance, an independent determination of the optical depth with an accuracy of σ(τreio)=0.001 (which might be achievable, although this is subject to astrophysical uncertainties) would decrease the uncertainty down to σ(Mν)=12 meV.
Lepton jets and low-mass sterile neutrinos at hadron colliders
NASA Astrophysics Data System (ADS)
Dube, Sourabh; Gadkari, Divya; Thalapillil, Arun M.
2017-09-01
Sterile neutrinos, if they exist, are potential harbingers for physics beyond the Standard Model. They have the capacity to shed light on our flavor sector, grand unification frameworks, dark matter sector and origins of baryon antibaryon asymmetry. There have been a few seminal studies that have broached the subject of sterile neutrinos with low, electroweak-scale masses (i.e. ΛQCD≪mNR≪mW± ) and investigated their reach at hadron colliders using lepton jets. These preliminary studies nevertheless assume background-free scenarios after certain selection criteria which are overly optimistic and untenable in realistic situations. These lead to incorrect projections. The unique signal topology and challenging hadronic environment also make this mass-scale regime ripe for a careful investigation. With the above motivations, we attempt to perform the first systematic study of low, electroweak-scale, right-handed neutrinos at hadron colliders, in this unique signal topology. There are currently no active searches at hadron colliders for sterile neutrino states in this mass range, and we frame the study in the context of the 13 TeV high-luminosity Large Hadron Collider and the proposed FCC-hh/SppC 100 TeV p p -collider.
NASA Astrophysics Data System (ADS)
Borah, Debasish
2017-02-01
We revisit the possibility of generating a nonzero reactor mixing angle in a scenario where there is a sterile neutrino at the eV scale apart from the usual three sub-eV scale active neutrinos. We show that the 3 ×3 active neutrino mass matrix can possess a μ -τ symmetry and can still be consistent with the nonzero value of the reactor mixing angle θ13 if this μ -τ symmetry is broken in the sterile neutrino sector. We first propose a simple model based on the discrete flavor symmetry A4×Z3×Z3' to realize such a scenario and then numerically evaluate the complete 3 +1 neutrino parameter space that allows such a possibility. We show that the possibility of generating a nonzero θ13 can, in general, remain valid even if the present 3 +1 neutrino global fit data get ruled out by future experiments. We also discuss the possible implications at neutrinoless double beta decay (0 ν β β ) experiments in view of the latest results from the KamLAND-Zen experiment.
Neutrino mixing in a left-right model
NASA Astrophysics Data System (ADS)
Martins Simões, J. A.; Ponciano, J. A.
We study the mixing among different generations of massive neutrino fields in a mass terms in the Yukawa sector. Parity can be spontaneously broken at a scale model can accommodate a consistent pattern for neutral fermion masses as well as neutrino oscillations. The left and right sectors can be connected by a new neutral current. PACS: 12.60.-i, 14.60.St, 14.60.Pq
Classically conformal radiative neutrino model with gauged B - L symmetry
NASA Astrophysics Data System (ADS)
Okada, Hiroshi; Orikasa, Yuta
2016-09-01
We propose a classically conformal model in a minimal radiative seesaw, in which we employ a gauged B - L symmetry in the standard model that is essential in order to work the Coleman-Weinberg mechanism well that induces the B - L symmetry breaking. As a result, nonzero Majorana mass term and electroweak symmetry breaking simultaneously occur. In this framework, we show a benchmark point to satisfy several theoretical and experimental constraints. Here theoretical constraints represent inert conditions and Coleman-Weinberg condition. Experimental bounds come from lepton flavor violations (especially μ → eγ), the current bound on the Z‧ mass at the CERN Large Hadron Collider, and neutrino oscillations.
Saoulidou, Niki
2016-07-12
Neutrino oscillations provide the first evidenceÂ for physics beyond the Standard Model. I will briefly overview the neutrino "hi-story", describing key discoveries over the past decades that shaped our understanding of neutrinos and their behavior. Fermilab was, is and hopefully will be at the forefront of the accelerator neutrino experiments.Â NuMI, the most powerful accelerator neutrino beam in the world has ushered us into the era of precise measurements. Its further upgrades may give a chance to tackle the remaining mysteries of the neutrino mass hierarchy and possible CP violation.
Oscillating decay rate in electron capture and the neutrino mass difference
NASA Astrophysics Data System (ADS)
Peshkin, Murray
2015-04-01
Reported oscillations in the rate of decay of certain ions by K -electron capture have raised questions about whether and how such oscillations can arise in quantum-mechanical theory and whether they can measure the neutrino mass difference. Here I show that simple principles of quantum mechanics answer some questions and clarify what must be performed theoretically or experimentally to answer some others. The principal result is that quantum mechanics does allow mass-difference-dependent oscillations in principle, but it imposes conditions not obeyed by the approximate dynamical models that have been put forth up to now. In particular, indirect coupling between two neutrino mass channels must be taken into account. What needs to be done experimentally and theoretically is discussed.
NASA Astrophysics Data System (ADS)
Zhao, Ming-Ming; Li, Yun-He; Zhang, Jing-Fei; Zhang, Xin
2017-08-01
We investigate how the properties of dark energy affect the cosmological measurements of neutrino mass and extra relativistic degrees of freedom. We limit ourselves to the most basic extensions of Λ cold dark matter (CDM) model, i.e. the wCDM model with one additional parameter w, and the w0waCDM model with two additional parameters, w0 and wa. In the cosmological fits, we employ the 2015 cosmic microwave background temperature and polarization data from the Planck mission, in combination with low-redshift measurements such as the baryon acoustic oscillations, Type Ia supernovae and the Hubble constant (H0). Given effects of massive neutrinos on large-scale structure, we further include weak lensing, redshift space distortion, Sunyaev-Zeldovich cluster counts and Planck lensing data. We show that, though the cosmological constant Λ is still consistent with the current data, a phantom dark energy (w < -1) or an early phantom dark energy (i.e. quintom evolving from w < -1 to w > -1) is slightly more favoured by current observations, which leads to the fact that in both wCDM and w0waCDM models we obtain a larger upper limit of ∑mν. We also show that in the three dark energy models, the constraints on Neff are in good accordance with each other, all in favour of the standard value 3.046, which indicates that the dark energy parameters almost have no impact on constraining Neff. Therefore, we conclude that the dark energy parameters can exert a significant influence on the cosmological weighing of neutrinos, but almost cannot affect the constraint on dark radiation.
Supernova neutrinos in a strangeon star model
NASA Astrophysics Data System (ADS)
Yuan, Mao; Lu, Ji-Guang; Yang, Zhi-Liang; Lai, Xiao-Yu; Xu, Ren-Xin
2017-09-01
The neutrino burst detected during supernova SN 1987A is explained in a strangeon star model, in which it is proposed that a pulsar-like compact object is composed of strangeons (strangeon: an abbreviation for “strange nucleon”). A nascent strangeon star’s initial internal energy is calculated, with the inclusion of pion excitation (energy around 1053 erg, comparable to the gravitational binding energy of a collapsed core). A liquid-solid phase transition at temperature ∼ 1‑2 MeV may occur only a few tens of seconds after core collapse, and the thermal evolution of a strangeon star is then modeled. It is found that the neutrino burst observed from SN 1987A can be reproduced in such a cooling model.
Final scientific and technical report: New experiments to measure the neutrino mass scale
Monreal, Benjamin
2016-11-19
In this work, we made material progress towards future measurements of the mass of the neutrino. The neutrino is a fundamental particle, first observed in the 1950s and subjected to particularly intense study over the past 20 years. It is now known to have some, non-zero mass, but we are in an unusual situation of knowing the mass exists but not knowing what value it takes. The mass may be determined by precise measurements of certain radioactive decay distributions, particularly the beta decay of tritium. The KATRIN experiment is an international project which is nearing the beginning of a tritium measurement campaign using a large electrostatic spectrumeter. This research included participation in KATRIN, including construction and delivery of a key calibration subsystem, the ``Rear Section''. To obtain sensitivity beyond KATRIN's, new techniques are required; this work included R\\&D on a new technique we call CRES (Cyclotron Resonance Electron Spectroscopy) which has promise to enable even-more-sensitive tritium decay measurements. We successfully carried out CRES spectroscopy in a model system in 2014, making an important step towards the design of a next-generation tritium experiment with new neutrino mass measurement abilities.
Effect of atmospheric flux uncertainties on the determination of the neutrino mass hierarchy
NASA Astrophysics Data System (ADS)
Sandroos, Joakim; Erhardt, Thomas; Arlen, Tim; Böser, Sebastian
2016-04-01
The next generation of large-volume neutrino telescopes will include low-energy subarrays which will be able to measure neutrinos with energies of a few GeV. In this energy range the primary signal below the horizon is neutrinos created by cosmic ray interactions in the atmosphere. The measured event rate will depend on the neutrino mass hierarchy, allowing determination of this quantity to a significance level of about 3.5 sigma within a 5-year period, mostly limited by systematic uncertainties. We present here the impact of the uncertainties on the atmospheric neutrino flux normalization on the determination of the neutrino mass hierarchy. We suggest constraining the systematic uncertainties by including the downgoing neutrino sample, which will increase the significance. This work was performed using simulation data from the low-energy extension to the IceCube detector located at the geographic south pole, PINGU, and is relevant to a wide range of other experiments.
Higgs lepton flavour violation: UV completions and connection to neutrino masses
NASA Astrophysics Data System (ADS)
Herrero-García, Juan; Rius, Nuria; Santamaria, Arcadi
2016-11-01
We study lepton violating Higgs (HLFV) decays, first from the effective field theory (EFT) point of view, and then analysing the different high-energy realizations of the operators of the EFT, highlighting the most promising models. We argue why two Higgs doublet models can have a BR( h → τ μ) ˜ 0 .01, and why this rate is suppressed in all other realizations including vector-like leptons. We further discuss HLFV in the context of neutrino mass models: in most cases it is generated at one loop giving always BR( h → τ μ) < 10-4 and typically much less, which is beyond experimental reach. However, both the Zee model and extended left-right symmetric models contain extra SU(2) doublets coupled to leptons and could in principle account for the observed excess, with interesting connections between HLFV and neutrino parameters.
Leptogenesis with many neutrinos
Eisele, Marc-Thomas
2008-02-15
We consider leptogenesis in scenarios with many neutrino singlets. We find that the lower bound for the reheating temperature can be significantly relaxed with respect to the hierarchical three neutrino case. We further argue that the upper bound for the neutrino mass scale from leptogenesis gets significantly lifted in these scenarios. As a specific realization, we then discuss an extradimensional model, where the large number of neutrinos is provided by Kaluza-Klein excitations.
Neutrino masses and mixing with seesaw mechanism and universal breaking of extended democracy
NASA Astrophysics Data System (ADS)
Akhmedov, E. K.; Branco, G. C.; Joaquim, F. R.; Silva-Marcos, J. 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. The structure of the resulting effective mass matrix of light neutrinos is stable against the RGE evolution, and a good fit to all solar and atmospheric neutrino data is obtained.
Minakata, H.; Nunokawa, H.; Parke, Stephen J.; Zukanovich Funchal, R.; /Sao Paulo U.
2006-09-01
In this talk, the authors discuss the possibility of determining the neutrino mass hierarchy by comparing the two effective atmospheric neutrino mass squared differences measured, respectively, in electron, and in muon neutrino disappearance oscillation experiments. if the former, is larger (smaller) than the latter, the mass hierarchy is of normal (inverted) type. They consider two very high precision (a few per mil) measurements of such mass squared differences by the phase II of the T2K (Tokai-to-Kamioka) experiment and by the novel Moessbauer enhanced resonant {bar {nu}}{sub e} absorption technique. Under optimistic assumptions for the systematic errors of both measurements, they determine the region of sensitivities where the mass hierarchy can be distinguished. Due to the tight space limitation, they present only the general idea and show a few most important plots.
Generalized Friedberg-Lee model for CP violation in neutrino physics
NASA Astrophysics Data System (ADS)
Razzaghi, N.; Gousheh, S. S.
2012-09-01
We propose a phenomenological model of Dirac neutrino mass operator based on the Friedberg-Lee neutrino mass model to include CP violation. By considering the most general set of complex coefficients, and imposing the condition that the mass eigenvalues are real, we find a neutrino mass matrix which is non-Hermitian, symmetric, and magic. In particular, we find that the requirement of obtaining real mass eigenvalues by transferring the residual phases to the mass eigenstates self-consistently dictates the following relationship between the imaginary part of the mass matrix elements B and the parameters of the Friedberg-Lee model: B=±(3)/(4)(a-br)2sin22θ13cos2θ12. We obtain inverted neutrino mass hierarchy m3=0. Making a correspondence between our model and the experimental data produces stringent conditions on the parameters as follows: 35.06°≲θ12≲36.27°, θ23=45°, 7.27°≲θ13≲11.09°, and 82.03°≲δ≲85.37°. We get mildly broken μ-τ symmetry, which reduces the resultant neutrino mixing pattern from tri-bimaximal to trimaximal. The CP violation as measured by the Jarlskog parameter is restricted by 0.027≲J≲0.044.
Naturally light Dirac neutrino in Left-Right Symmetric Model
NASA Astrophysics Data System (ADS)
Borah, Debasish; Dasgupta, Arnab
2017-06-01
We study the possibility of generating tiny Dirac masses of neutrinos in Left-Right Symmetric Model (LRSM) without requiring the existence of any additional symmetries. The charged fermions acquire masses through a universal seesaw mechanism due to the presence of additional vector like fermions. The neutrinos acquire a one-loop Dirac mass from the same additional vector like charged leptons without requiring any additional discrete symmetries. The model can also be extended by an additional Z2 symmetry in order to have a scotogenic version of this scenario predicting a stable dark matter candidate. We show that the latest Planck upper bound on the effective number of relativistic degrees of freedom Neff=3.15 ± 0.23 tightly constrains the right sector gauge boson masses to be heavier than 3.548 TeV . This bound on gauge boson mass also affects the allowed values of right scalar doublet dark matter mass from the requirement of satisfying the Planck bound on dark matter relic abundance. We also discuss the possible implications of such a scenario in charged lepton flavour violation and generating observable electric dipole moment of leptons.
Maximal atmospheric neutrino mixing in an SU(5) model
NASA Astrophysics Data System (ADS)
Grimus, W.; Lavoura, L.
2003-05-01
We show that maximal atmospheric and large solar neutrino mixing can be implemented in SU(5) gauge theories, by making use of the U(1) F symmetry associated with a suitably defined family number F, together with a Z2 symmetry which does not commute with F. U(1) F is softly broken by the mass terms of the right-handed neutrino singlets, which are responsible for the seesaw mechanism; in additio n, U(1) F is also spontaneously broken at the electroweak scale. In our scenario, lepton mixing stems exclusively from the right-handed-neutrino Majorana mass matrix, whereas the CKM matrix originates solely in the up-type-quark sector. We show that, despite the non-supersymmetric character of our model, unification of the gauge couplings can be achieved at a scale 1016 GeV < m U < 1019 GeV; indeed, we have found a particula r solution to this problem which yields results almost identical to the ones of the minimal supersymmetric standard model.
Dynamics of neutrino lumps in growing neutrino quintessence
NASA Astrophysics Data System (ADS)
Casas, Santiago; Pettorino, Valeria; Wetterich, Christof
2016-11-01
We investigate the formation and dissipation of large-scale neutrino structures in cosmologies where the time evolution of dynamical dark energy is stopped by a growing neutrino mass. In models where the coupling between neutrinos and dark energy grows with the value of the scalar cosmon field, the evolution of neutrino lumps depends on the neutrino mass. For small masses the lumps form and dissolve periodically, leaving only a small backreaction of the neutrino structures on the cosmic evolution. This process heats the neutrinos to temperatures far above the photon temperature, such that neutrinos acquire again an almost relativistic equation of state. The present equation of state of the combined cosmon-neutrino fluid is very close to -1 . By contrast, for larger neutrino masses, the lumps become stable. The highly concentrated neutrino structures entail a large backreaction similar to the case of a constant neutrino-cosmon coupling. A present average neutrino mass of around 0.5 eV seems to be compatible with observations so far. For masses lower than this value, neutrino-induced gravitational potentials remain small, making the lumps difficult to detect.
Cosmogenic Neutrinos Challenge the Cosmic-ray Proton Dip Model
NASA Astrophysics Data System (ADS)
Heinze, Jonas; Boncioli, Denise; Bustamante, Mauricio; Winter, Walter
2016-07-01
The origin and composition of ultra-high-energy cosmic rays (UHECRs) remain a mystery. The proton dip model describes their spectral shape in the energy range above 109 GeV by pair production and photohadronic interactions with the cosmic microwave background. The photohadronic interactions also produce cosmogenic neutrinos peaking around 109 GeV. We test whether this model is still viable in light of recent UHECR spectrum measurements from the Telescope Array experiment and upper limits on the cosmogenic neutrino flux from IceCube. While two-parameter fits have been already presented, we perform a full scan of the three main physical model parameters: source redshift evolution, injected proton maximal energy, and spectral index. We find qualitatively different conclusions compared to earlier two-parameter fits in the literature: a mild preference for a maximal energy cutoff at the sources instead of the Greisen-Zatsepin-Kuzmin cutoff, hard injection spectra, and strong source evolution. The predicted cosmogenic neutrino flux exceeds the IceCube limit for any parameter combination. As a result, the proton dip model is challenged at more than 95% C.L. This is strong evidence against this model independent of mass composition measurements.
Neutrino exotica in the skew E6 left-right model
NASA Astrophysics Data System (ADS)
Ma, Ernest
2000-11-01
With the particle content of the 27 representation of E6, a skew left-right supersymmetric gauge model was proposed many years ago, with a variety of interesting phenomenological implications. The neutrino sector of this model offers a natural framework for obtaining small Majorana masses for νe, νμ, and ντ, with the added bonus of accommodating 2 light sterile neutrinos.
Radiofrequency instruments to search for new particles and measure neutrino mass
NASA Astrophysics Data System (ADS)
Rybka, Gray
2016-09-01
The smallness of the neutrino mass scale and renewed interest in sub-eV particles to explain dark matter and dark energy suggest that physics beyond the standard model may be found by looking at energies much lower than those traditionally associated with nuclear physics. Fortuitously, recent advances in microwave and radiofrequency electronics from fields such as radio astronomy and quantum computing offer the ability to access these energy scales with unprecedented sensitivity. I will discuss the application of these advances to nuclear physics, highlighting experiments using microwave technology to probe the neutrino mass scale and experiments using of quantum radiofrequency electronics to search for sub-eV particles such as axions.
Heavy neutrinos and lepton flavor violation in left-right symmetric models at the LHC
NASA Astrophysics Data System (ADS)
Das, S. P.; Deppisch, F. F.; Kittel, O.; Valle, J. W. F.
2012-09-01
We discuss lepton flavor violating processes induced in the production and decay of heavy right-handed neutrinos at the LHC. Such particles appear in left-right symmetrical extensions of the standard model as the messengers of neutrino mass generation, and can have masses at the TeV scale. We determine the expected sensitivity on the right-handed neutrino mixing matrix, as well as on the right-handed gauge boson and heavy neutrino masses. By comparing the sensitivity of the LHC with that of searches for low energy lepton flavor violating processes, we identify favorable areas of the parameter space to explore the complementarity between lepton flavor violating at low and high energies.
Los Alamos Science, Number 25 -- 1997: Celebrating the Neutrino
DOE R&D Accomplishments Database
Cooper, N. G. ed.
1997-01-01
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.
Los Alamos Science, Number 25 -- 1997: Celebrating the neutrino
Cooper, N.G.
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.
NEW NEUTRINO MASS BOUNDS FROM SDSS-III DATA RELEASE 8 PHOTOMETRIC LUMINOUS GALAXIES
De Putter, Roland; Mena, Olga; Giusarma, Elena; Ho, Shirley; Seo, Hee-Jong; White, Martin; Ross, Nicholas P.; Cuesta, Antonio; Ross, Ashley J.; Percival, Will J.; Bizyaev, Dmitry; Brewington, Howard; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Daniel; Pan, Kaike; Shelden, Alaina; Simmons, Audrey; Kirkby, David; Schneider, Donald P.; and others
2012-12-10
We present neutrino mass bounds using 900,000 luminous galaxies with photometric redshifts measured from Sloan Digital Sky Survey III Data Release 8. The galaxies have photometric redshifts between z = 0.45 and z = 0.65 and cover 10,000 deg{sup 2}, thus probing a volume of 3 h {sup -3} Gpc{sup 3} and enabling tight constraints to be derived on the amount of dark matter in the form of massive neutrinos. A new bound on the sum of neutrino masses {Sigma}m{sub {nu}} < 0.27 eV, at the 95% confidence level (CL), is obtained after combining our sample of galaxies, which we call ''CMASS'', with Wilkinson Microwave Anisotropy Probe (WMAP) seven-year cosmic microwave background data and the most recent measurement of the Hubble parameter from the Hubble Space Telescope (HST). This constraint is obtained with a conservative multipole range of 30 < l < 200 in order to minimize nonlinearities, and a free bias parameter in each of the four redshift bins. We study the impact of assuming this linear galaxy bias model using mock catalogs and find that this model causes a small ({approx}1{sigma}-1.5{sigma}) bias in {Omega}{sub DM} h {sup 2}. For this reason, we also quote neutrino bounds based on a conservative galaxy bias model containing additional, shot-noise-like free parameters. In this conservative case, the bounds are significantly weakened, e.g., {Sigma}m{sub {nu}} < 0.38 eV (95% CL) for WMAP+HST+CMASS (l{sub max} = 200). We also study the dependence of the neutrino bound on the multipole range (l{sub max} = 150 versus l{sub max} = 200) and on which combination of data sets is included as a prior. The addition of supernova and/or baryon acoustic oscillation data does not significantly improve the neutrino mass bound once the HST prior is included. A companion paper describes the construction of the angular power spectra in detail and derives constraints on a general cosmological model, including the dark energy equation of state w and the spatial curvature {Omega}{sub K
New Neutrino Mass Bounds from SDSS-III Data Release 8 Photometric Luminous Galaxies
NASA Astrophysics Data System (ADS)
de Putter, Roland; Mena, Olga; Giusarma, Elena; Ho, Shirley; Cuesta, Antonio; Seo, Hee-Jong; Ross, Ashley J.; White, Martin; Bizyaev, Dmitry; Brewington, Howard; Kirkby, David; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Daniel; Pan, Kaike; Percival, Will J.; Ross, Nicholas P.; Schneider, Donald P.; Shelden, Alaina; Simmons, Audrey; Snedden, Stephanie
2012-12-01
We present neutrino mass bounds using 900,000 luminous galaxies with photometric redshifts measured from Sloan Digital Sky Survey III Data Release 8. The galaxies have photometric redshifts between z = 0.45 and z = 0.65 and cover 10,000 deg2, thus probing a volume of 3 h -3 Gpc3 and enabling tight constraints to be derived on the amount of dark matter in the form of massive neutrinos. A new bound on the sum of neutrino masses ∑m ν < 0.27 eV, at the 95% confidence level (CL), is obtained after combining our sample of galaxies, which we call "CMASS," with Wilkinson Microwave Anisotropy Probe (WMAP) seven-year cosmic microwave background data and the most recent measurement of the Hubble parameter from the Hubble Space Telescope (HST). This constraint is obtained with a conservative multipole range of 30 < l < 200 in order to minimize nonlinearities, and a free bias parameter in each of the four redshift bins. We study the impact of assuming this linear galaxy bias model using mock catalogs and find that this model causes a small (~1σ-1.5σ) bias in ΩDM h 2. For this reason, we also quote neutrino bounds based on a conservative galaxy bias model containing additional, shot-noise-like free parameters. In this conservative case, the bounds are significantly weakened, e.g., ∑m ν < 0.38 eV (95% CL) for WMAP+HST+CMASS (lmax = 200). We also study the dependence of the neutrino bound on the multipole range (lmax = 150 versus lmax = 200) and on which combination of data sets is included as a prior. The addition of supernova and/or baryon acoustic oscillation data does not significantly improve the neutrino mass bound once the HST prior is included. A companion paper describes the construction of the angular power spectra in detail and derives constraints on a general cosmological model, including the dark energy equation of state w and the spatial curvature Ω K , while a second companion paper presents a measurement of the scale of baryon acoustic oscillations from
Neutrino oscillations: From a historical perspective to the present status
NASA Astrophysics Data System (ADS)
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.
Neutrino oscillations: from an historical perspective to the present status
NASA Astrophysics Data System (ADS)
Bilenky, S.
2016-05-01
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.
Neutrinos and lepton flavor violation in the left-right twin Higgs model
Abada, Asmaa; Hidalgo, Irene
2008-06-01
We analyze the lepton sector of the left-right twin Higgs model. This model offers an alternative way to solve the 'little hierarchy' problem of the standard model. We show that one can achieve an effective seesaw to explain the origin of neutrino masses and that this model can accommodate the observed neutrino masses and mixings. We have also studied the lepton flavor violation process l{sub i}{yields}l{sub j}{gamma} and discussed how the experimental bound from these branching ratios constrains the scale of symmetry breaking of this twin Higgs model.
Starobinsky-like inflation, supercosmology and neutrino masses in no-scale flipped SU(5)
NASA Astrophysics Data System (ADS)
Ellis, John; Garcia, Marcos A. G.; Nagata, Natsumi; Nanopoulos, Dimitri V.; Olive, Keith A.
2017-07-01
We embed a flipped SU(5) × U(1) GUT model in a no-scale supergravity framework, and discuss its predictions for cosmic microwave background observables, which are similar to those of the Starobinsky model of inflation. Measurements of the tilt in the spectrum of scalar perturbations in the cosmic microwave background, ns, constrain significantly the model parameters. We also discuss the model's predictions for neutrino masses, and pay particular attention to the behaviours of scalar fields during and after inflation, reheating and the GUT phase transition. We argue in favor of strong reheating in order to avoid excessive entropy production which could dilute the generated baryon asymmetry.
More is different: Reconciling eV sterile neutrinos with cosmological mass bounds
NASA Astrophysics Data System (ADS)
Tang, Yong
2015-11-01
It is generally expected that adding light sterile species would increase the effective number of neutrinos, Neff. In this paper we discuss a scenario that Neff can actually decrease due to the neutrino oscillation effect if sterile neutrinos have self-interactions. We specifically focus on the eV mass range, as suggested by the neutrino anomalies. With large self-interactions, sterile neutrinos are not fully thermalized in the early Universe because of the suppressed effective mixing angle or matter effect. As the Universe cools down, flavor equilibrium between active and sterile species can be reached after big bang nucleosynthesis (BBN) epoch, but leading to a decrease of Neff. In such a scenario, we also show that the conflict with cosmological mass bounds on the additional sterile neutrinos can be relaxed further when more light species are introduced. To be consistent with the latest Planck results, at least 3 sterile species are needed.
Neutrino oscillations in a stochastic model for space-time foam
Alexandre, J.; Farakos, K.; Mavromatos, N. E.; Pasipoularides, P.
2008-05-15
We study decoherence models for flavor oscillations in four-dimensional stochastically fluctuating space-times and discuss briefly the sensitivity of current neutrino experiments to such models. We demonstrate the model dependence of the associated decoherence-induced damping coefficients in front of the oscillatory terms in the respective transition probabilities between flavors. Within the context of specific models of foam, involving pointlike D-branes and leading to decoherence-induced damping which is inversely proportional to the neutrino energies, we also argue that future limits on the relevant decoherence parameters coming from TeV astrophysical neutrinos, to be observed in ICE-CUBE, are not far from theoretically expected values with Planck-mass suppression. Ultrahigh energy neutrinos from gamma ray bursts at cosmological distances can also exhibit in principle sensitivity to such effects.
NASA Astrophysics Data System (ADS)
Kopylov, A. V.
1993-01-01
The ratios of the fluxes of solar neutrinos from the CNO cycle to those of boron neutrinos are less model-dependent than the fluxes themselves in the standard Bahcall-Ulrich solar model. The uncertainties for these ratios are calculated at the level of three standard deviations. Their importance in the overall formulation of the problem of detecting solar neutrinos is discussed.
Two-loop snail diagrams: relating neutrino masses to dark matter
NASA Astrophysics Data System (ADS)
Farzan, Yasaman
2015-05-01
Various mechanisms have been developed to explain the origin of neutrino masses. One of them is radiative mass generation. Two-loop mass generation is of particular interest because the masses and couplings of new particles propagating in the loop can be in the range testable by other experiments and observations. In order for the radiative mass suppression to be reliable, it should be guaranteed that lower loop contributions are suppressed. Based on loop topology and the form of electroweak presentation of the particles propagating in the loop, one can determine whether a lower — and therefore dominant — loop contribution is possible. We present a model based on these general considerations which leads to neutrino masses via a two-loop diagram which we dub as "snail-diagram". The model has two natural candidates for dark matter one of them being a neutral Dirac fermion which can satisfy the conditions of the thermal freeze-out scenario by annihilation to lepton pairs. We comment on the possibility of explaining the GeV gamma ray excess observed by Fermi-LAT from the region close to the Galaxy Center. We also discuss possible signals at the LHC and at experiments searching for lepton flavor violating rare decays.
Beacom, J.F.; Vogel, P.
1998-11-01
Core-collapse supernovae emit of order 10{sup 58} neutrinos and antineutrinos of all flavors over several seconds, with average energies of 10{endash}25 MeV. In the Sudbury Neutrino Observatory (SNO), which begins operation this year, neutrinos and antineutrinos of all flavors can be detected by reactions which break up the deuteron. For a future Galactic supernova at a distance of 10 kpc, several hundred events will be observed in SNO. The {nu}{sub {mu}} and {nu}{sub {tau}} neutrinos and antineutrinos are of particular interest, as a test of the supernova mechanism. In addition, it is possible to measure or limit their masses by their delay (determined from neutral-current events) relative to the {bar {nu}}{sub e} neutrinos (determined from charged-current events). Numerical results are presented for such a future supernova as seen in SNO. Under reasonable assumptions, and in the presence of the expected counting statistics, a {nu}{sub {mu}} or {nu}{sub {tau}} mass down to about 30 eV can be simply and robustly determined. If zero delay is measured, then the mass limit is {ital independent} of the distance D. At present, this seems to be the best possibility for direct determination of a {nu}{sub {mu}} or {nu}{sub {tau}} mass within the cosmologically interesting range. We also show how to separately study the supernova and neutrino physics, and how changes in the assumed supernova parameters would affect the mass sensitivity. {copyright} {ital 1998} {ital The American Physical Society}
NASA Technical Reports Server (NTRS)
Kimble, R.; Bowyer, S.; Jakobsen, P.
1981-01-01
Upper limits to astronomical photon backgrounds are used to derive constraints on the radiative lifetime of neutrinos. With the assumption that the radiative decay dominates the decay routes available, comparisons with predicted fluxes exclude radiative lifetimes between 10 to the 13th and 10 to the 22nd-23rd sec for neutrinos which decay to lighter neutrinos and 5-50 eV photons. For a secondary neutrino mass much less than the parent neutrino mass, this photon-energy range corresponds to a parent-neutrino-mass range of 10-100 eV/c-squared.
Fermion Masses from Six Dimensions and Implications for Majorana Neutrinos
NASA Astrophysics Data System (ADS)
Frère, J.-M.; Libanov, M.; Mollet, S.; Troitsky, S.
2015-06-01
In these notes, we review the main results of our approach to fermion masses. The marge mass ratios between fermions, confronted with a unique breaking mechanism leading to vector bosons masses, led us to consider the possibility that they result from the overlap of fermion wave functions. Such overlaps vary indeed very strongly if the observed fermion families in 4 dimensions originate in a single family in 6 dimensions, through localized wave functions. This framework leads in a natural way to large mass ratios and small mixing angles between quarks. What came as a surprise is that if we impose that neutrinos behave as 2- component (“Majorana”) particles in 4D, a completely different situation is obtained for them. Instead of diagonal mass matrices, anti-diagonal ones emerge and lead to a generic prediction of combined inverted hierarchy, large mixing angles in the leptonicsector, and a suppression of neutrinoless-double beta decay placing it at the lower limit of the inverted hierarchy branch, a challenging situation for on-going and planned experiments. Our approach predicted the size of the θ13 mixing angle before its actual measurement. Possible signals at colliders are only briefly evoked.
Are neutrinos their own antiparticles?
Kayser, Boris; /Fermilab
2009-03-01
We explain the relationship between Majorana neutrinos, which are their own antiparticles, and Majorana neutrino masses. We point out that Majorana masses would make the neutrinos very distinctive particles, and explain why many theorists strongly suspect that neutrinos do have Majorana masses. The promising approach to confirming this suspicion is to seek neutrinoless double beta decay. We introduce a toy model that illustrates why this decay requires nonzero neutrino masses, even when there are both right-handed and left-handed weak currents.
Supernova heavy element nucleosynthesis: Can it tell us about neutrino masses?
Fuller, George M.
1997-05-20
Here we describe a new probe of neutrino properties based on heavy element nucleosynthesis. This technique is in many ways akin to the familiar light element Primordial Nucleosynthesis probe of conditions in the early universe. Our new probe is based on the fact that neutrino masses and vacuum mixings can engender matter-enhanced neutrino flavor transformation in the post core bounce supernova environment. Transformations of the type {nu}{sub {mu}}{sub (r)}<-->{nu}{sub e} in this site will have significant effects on the synthesis of the rapid neutron capture (r-Process) elements and the light p-nuclei. We suggest that an understanding of the origin of these nuclides, combined with the measured abundances of these species, may provide a ''Rosetta Stone'' for neutrino properties. Heavy element nucleosynthesis abundance considerations give either constraints/evidence for neutrino masses and flavor mixings, or strong constraints on the site of origin of r-Process nucleosynthesis. The putative limits on neutrino characteristics are complimentary to those derived from laboratory neutrino oscillation studies and solar and atmospheric neutrino experiments. Preliminary studies show that the existence of r-Process nuclei in the abundances observed in the Galaxy cannot be understood unless neutrinos have small masses (possibly in the cosmologically significant range)
Quantum Effects for the Neutrino Mixing Matrix in the Democratic-Type Model
NASA Astrophysics Data System (ADS)
Miura, T.; Takasugi, E.; Yoshimura, M.
2000-12-01
We investigate the quantum effects for the democratic-type neutrino mass matrix given at the right-handed neutrino mass scale mR in order to see (i) whether the prediction 𗏷=-π/4 which is crucial to explain the atmospheric neutrino anomaly is stable, (ii) how 𗏬 and 𗏭 behave, and (iii) whether the predicted Dirac CP phase δ maintains maximal size at the weak scale mZ. We find that for the (inversely) hierarchical mass spectrum with m1 ~ m2, 𗏷 and 𗏭 are stable, while 𗏬 is not stable. This leads to the possibility that the solar neutrino mixing angle can become large at mZ even if it is taken to be small at mR. We also show that δ maintains almost maximal size for the above-mentioned mass spectrum, and our model predicts a large CP violation effect in future neutrino oscillation experiments in the case that the solar neutrino puzzle is explained by the large mixing angle MSW solution.
Neutrino oscillation, finite self-mass and general Yang-Mills symmetry
NASA Astrophysics Data System (ADS)
Hsu, Jong-Ping
2016-10-01
The conservation of lepton number is assumed to be associated with a general Yang-Mills (gYM) symmetry. New transformations involve (Lorentz) vector gauge functions and characteristic phase functions, and they form a group. General Yang-Mills fields are associated with new fourth-order equations and linear potentials. Lepton self-masses turn out to be finite and proportional to the inverse of lepton masses, which implies that neutrinos should have nonzero masses. Thus, gYM symmetry could provide an understanding of neutrino oscillations and suggests that neutrinos with masses and very weak leptonic force may play a role in dark matter.
Correction to Neutrino Mass Square Difference in the Co-Bimaximal Mixings due to Quantum Gravity
NASA Astrophysics Data System (ADS)
Koranga, Bipin Singh; Narayan, Mohan
2017-08-01
We consider non-renormalizable interaction term as a perturbation of the neutrino mass matrix. We assume that the neutrino masses and mixing arise through physics at a scale intermediate between Planck scale and the electroweak breaking scale. We also assume that, just above the electroweak breaking scale, neutrino masses are nearly degenerate and their mixing is Co-bimaximal mixing by assumming mixing angle θ _{13}≠ 0=10°,θ _{23}={π}/{4}, tanθ _{12}2={1-3sinθ_{13}2}/{2}=34° and Dirac phase δ =± {π}/{2}. . Quantum gravity (Planck scale effects) lead to an effective S U(2) L × U(1) invariant dimension-5 Lagrangian involving neutrino and Higgs fields. On symmetry breaking, this operator gives rise to correction to the above masses and mixing. The gravitational interaction M X = M p l , we find that for degenerate neutrino mass spectrum, the considered perturbation term change the {Δ }_{21}^' } by 12% and {Δ }_{31}^' } mass square difference is unchanged above GUT scale. The nature of gravitational interaction demands that the element of this perturbation matrix should be independent of flavor indices. In this paper, we study the quantum gravity effects on neutrino mass square difference, namely modified dispersion relation for neutrino mass square differences.
4-Neutrino mass schemes and the likelihood of (3+1)-mass spectra
NASA Astrophysics Data System (ADS)
Grimus, W.; Schwetz, T.
2001-04-01
We examine the (3+1)-class of 4-neutrino mass spectra within a rigorous statistical analysis based on the Bayesian approach to probability. The data of the Bugey, CDHS and KARMEN experiments are combined by using a likelihood function. Our statistical approach allows us to incorporate solar and atmospheric neutrino data and also the result of the CHOOZ experiment via inequalities which involve elements of the neutrino mixing matrix and are derived from these data. For any short-baseline Δ m^2 we calculate a bound on the LSND transition amplitude A_{μ;e} and find that, in the Δ m^2 A_{μ;e} plane, there is no overlap between the 99% CL region allowed by the latest LSND analysis and the region allowed by our bound on A_{μ;e} at 95% CL; there are some small overlap regions if we take the bound at 99% CL. Therefore, we conclude that, with the existing data, the (3+1)-neutrino mass spectra are not very likely. However, treating the (2+2)-spectra with our method, we find that they are well compatible with all data.
Discrete flavor symmetries and models of neutrino mixing
Altarelli, Guido; Feruglio, Ferruccio
2010-07-15
Application of non-Abelian finite groups to the theory of neutrino masses and mixing is reviewed, which is strongly suggested by the agreement of the tribimaximal (TB) mixing pattern with experiment. After summarizing the motivation and the formalism, concrete models based on A{sub 4}, S{sub 4}, and other finite groups, and their phenomenological implications are discussed, including lepton flavor violating processes, leptogenesis, and the extension to quarks. As an alternative to TB mixing application of discrete flavor symmetries to quark-lepton complementarity and bimaximal mixing is also considered.
Bursts of gravitational radiation from superconducting cosmic strings and the neutrino mass spectrum
NASA Astrophysics Data System (ADS)
Mosquera Cuesta, H. J.; González, D. M.
2001-02-01
Berezinsky, Hnatyk and Vilenkin showed that superconducting cosmic strings could be central engines for cosmological gamma-ray bursts and for producing the neutrino component of ultra-high energy cosmic rays. A consequence of this mechanism would be that a detectable cusp-triggered gravitational wave burst should be released simultaneously with the /γ-ray surge. If contemporary measurements of both /γ and /ν radiation could be made for any particular source, then the cosmological time-delay between them might be useful for putting unprecedentedly tight bounds on the neutrino mass spectrum. Such measurements could consistently verify or rule out the model, since strictly correlated behaviour is expected for the duration of the event and for the time variability of the spectra.
Bursts of Gravitational Radiation from Superconducting Cosmic Strings and the Neutrino Mass Spectrum
NASA Astrophysics Data System (ADS)
Mosquera Cuesta, Herman J.; González, Danays Morejón
2001-09-01
Berezinsky, Hnatyk and Vilenkin showed that superconducting cosmic strings could be central engines for cosmological gamma-ray bursts and for producing the neutrino component of ultra-high energy cosmic rays. A consequence of this mechanism would be that a detectable cusp-triggered gravitational wave burst should be released simultaneously with the γ-ray surge. If contemporary measurements of both γ and ν radiation could be made for any particular source, then the cosmological time-delay between them might be useful for putting unprecedently tight bounds on the neutrino mass spectrum. Such measurements could consistently verify or rule out the model, since strictly correlated behaviour is expected for the duration of the event and for the time variability of the spectra.
Statistical Evaluation of Experimental Determinations of Neutrino Mass Hierarchy
X. Qian, A. Tan, W. Wang, J. J. Ling, R. D. McKeown, C. Zhang
2012-12-01
Statistical methods of presenting experimental results in constraining the neutrino mass hierarchy (MH) are discussed. Two problems are considered and are related to each other: how to report the findings for observed experimental data, and how to evaluate the ability of a future experiment to determine the neutrino mass hierarchy, namely, sensitivity of the experiment. For the first problem where experimental data have already been observed, the classical statistical analysis involves constructing confidence intervals for the parameter {Delta}m{sup 2}{sub 32}. These intervals are deduced from the parent distribution of the estimation of {Delta}m{sup 2}{sub 32} based on experimental data. Due to existing experimental constraints on |{Delta}m{sup 2}{sub 32}|, the estimation of {Delta}m{sup 2}{sub 32} is better approximated by a Bernoulli distribution (a Binomial distribution with 1 trial) rather than a Gaussian distribution. Therefore, the Feldman-Cousins approach needs to be used instead of the Gaussian approximation in constructing confidence intervals. Furthermore, as a result of the definition of confidence intervals, even if it is correctly constructed, its confidence level does not directly reflect how much one hypothesis of the MH is supported by the data rather than the other hypothesis. We thus describe a Bayesian approach that quantifies the evidence provided by the observed experimental data through the (posterior) probability that either one hypothesis of MH is true. This Bayesian presentation of observed experimental results is then used to develop several metrics to assess the sensitivity of future experiments. Illustrations are made using a simple example with a confined parameter space, which approximates the MH determination problem with experimental constraints on the |{Delta}m{sup 2}{sub 32}|.
NASA Astrophysics Data System (ADS)
Fogli, G. L.; Lisi, E.; Marrone, A.; Montanino, D.; Palazzo, A.; Rotunno, A. M.
2012-07-01
We perform a global analysis of neutrino oscillation data, including high-precision measurements of the neutrino mixing angle θ13 at reactor experiments, which have confirmed previous indications in favor of θ13>0. Recent data presented at the Neutrino 2012 conference are also included. We focus on the correlations between θ13 and the mixing angle θ23, as well as between θ13 and the neutrino CP-violation phase δ. We find interesting indications for θ23<π/4 and possible hints for δ˜π, with no significant difference between normal and inverted mass hierarchy.
FERMION MASSES AND NEUTRINO OSCILLATIONS IN SO(10) X SU(2)F*
CHEN, M-C.; MAHANTHAPPA, K.T.
2004-06-17
We present in this talk a model based on SO(10) x SU(2){sub F} having symmetric mass textures with 5 zeros constructed by us recently. The symmetric mass textures arising from the left-right symmetry breaking chain of SO(10) give rise to good predictions for the masses, mixing angles and CP violation measures in the quark and lepton sectors (including the neutrinos), all in agreement with the most up-to-date experimental data within 1 {sigma}. Various lepton flavor violating decays in our model are also investigated. Unlike in models with lop-sided textures, our prediction for the decay rate of {mu} + e{gamma} is much suppressed and yet it is large enough to be probed by the next generation of experiments. The observed baryonic asymmetry in the Universe can be accommodated in our model utilizing soft leptogenesis.
NASA Astrophysics Data System (ADS)
Díaz, Marco Aurelio; Koch, Benjamin; Rojas, Nicolás
2017-03-01
The Minimal Supersymmetric Extension of the Standard Model (MSSM) is able to explain the current data from neutrino physics. Unfortunately Split Supersymmetry as low energy approximation of this theory fails to generate a solar square mass difference, including after the addition of bilinear R-Parity Violation. In this work, it is shown how one can derive an effective low energy theory from the MSSM in the spirit of Split Supersymmetry, which has the potential of explaining the neutrino phenomenology. This is achieved by going beyond leading order in the process of integrating out heavy scalars from the original theory, which results in non-renormalizable operators in the effective low energy theory. It is found that in particular a d = 8 operator is crucial for the generation of the neutrino mass differences.
Hadronization processes in neutrino interactions
Katori, Teppei; Mandalia, Shivesh
2015-10-15
Next generation neutrino oscillation experiments utilize details of hadronic final states to improve the precision of neutrino interaction measurements. The hadronic system was often neglected or poorly modelled in the past, but they have significant effects on high precision neutrino oscillation and cross-section measurements. Among the physics of hadronic systems in neutrino interactions, the hadronization model controls multiplicities and kinematics of final state hadrons from the primary interaction vertex. For relatively high invariant mass events, many neutrino experiments rely on the PYTHIA program. Here, we show a possible improvement of this process in neutrino event generators, by utilizing expertise from the HERMES experiment. Finally, we estimate the impact on the systematics of hadronization models for neutrino mass hierarchy analysis using atmospheric neutrinos such as the PINGU experiment.
Very low energy supernovae from neutrino mass loss
Lovegrove, Elizabeth; Woosley, S. E.
2013-06-01
It now seems likely that some percentage of more massive supernova progenitors do not explode by any of the currently discussed explosion mechanisms. This has led to speculation concerning the observable transients that might be produced if such a supernova fails. Even if a prompt outgoing shock fails to form in a collapsing presupernova star, one must still consider the hydrodynamic response of the star to the abrupt loss of mass via neutrinos as the core forms a protoneutron star. Following a suggestion by Nadezhin, we calculate the hydrodynamical responses of typical supernova progenitor stars to the rapid loss of approximately 0.2-0.5 M {sub ☉} of gravitational mass from their centers. In a red supergiant star, a very weak supernova with total kinetic energy ∼10{sup 47} erg results. The binding energy of a large fraction of the hydrogen envelope before the explosion is of the same order and, depending upon assumptions regarding the maximum mass of a neutron star, most of it is ejected. Ejection speeds are ∼100 km s{sup –1} and luminosities ∼10{sup 39} erg s{sup –1} are maintained for about a year. A significant part of the energy comes from the recombination of hydrogen. The color of the explosion is extremely red and the events bear some similarity to 'luminous red novae', but have much lower speeds.
Very Low Energy Supernovae from Neutrino Mass Loss
NASA Astrophysics Data System (ADS)
Lovegrove, Elizabeth; Woosley, S. E.
2013-06-01
It now seems likely that some percentage of more massive supernova progenitors do not explode by any of the currently discussed explosion mechanisms. This has led to speculation concerning the observable transients that might be produced if such a supernova fails. Even if a prompt outgoing shock fails to form in a collapsing presupernova star, one must still consider the hydrodynamic response of the star to the abrupt loss of mass via neutrinos as the core forms a protoneutron star. Following a suggestion by Nadezhin, we calculate the hydrodynamical responses of typical supernova progenitor stars to the rapid loss of approximately 0.2-0.5 M ⊙ of gravitational mass from their centers. In a red supergiant star, a very weak supernova with total kinetic energy ~1047 erg results. The binding energy of a large fraction of the hydrogen envelope before the explosion is of the same order and, depending upon assumptions regarding the maximum mass of a neutron star, most of it is ejected. Ejection speeds are ~100 km s-1 and luminosities ~1039 erg s-1 are maintained for about a year. A significant part of the energy comes from the recombination of hydrogen. The color of the explosion is extremely red and the events bear some similarity to "luminous red novae," but have much lower speeds.
NASA Astrophysics Data System (ADS)
Feilitzsch, F. v.
1999-01-01
Since the pioneering experiment of R. Davis et al., which started neutrino astronomy by measuring the solar neutrinos via the inverse beta decay reaction on 37Cl, all solar neutrino experiments find a considerably lower flux than expected by standard solar models. This finding is generally called the solar neutrino problem. Many attempts have been made to explain this result by altering the solar models, or assuming different nuclear cross sections for fusion processes assumed to be the energy sources in the sun. There have been performed numerous experiments recently to investigate the different possibilities to explain the solar neutrino problem. These experiments covered solar physics with helioseismology, nuclear cross section measurements, and solar neutrino experiments. Up to now no convincing explanation based on "standard" physics was suggested. However, assuming nonstandard neutrino properties, i.e. neutrino masses and mixing as expected in most extensions of the standard theory of elementary particle physics, natural solutions for the solar neutrino problem can be found. It appears that with this newly invented neutrino astronomy fundamental information on astrophysics as well as elementary particle physics are tested uniquely. In this contribution an attempt is made to review the situation of the neutrino astronomy for solar neutrino spectroscopy and discuss the future prospects in this field.
NASA Astrophysics Data System (ADS)
Homma, Kensuke; Jinnouchi, Osamu
2003-04-01
The unphysical result of the negative mass square of the electron neutrinos recently reported in several tritium β-decay experiments, is one of the most attractive subjects. As a possible scenario to explain the anomaly, we have assumed a reaction with relic neutrinos which are predicted by the standard big bang cosmology. If such neutrinos could exist, the interaction of the relic neutrinos with the target tritium, νe + 3H → 3He + e- could be laid under the large amount of the β-decay process, H- > He + e- + bar ν e, which would cause a peak-like structure beyond the end-point in the Kurie plot. Based on the assumption, we evaluated the cross section from the event rate found in the peak by re-fitting to the 1991 data published by Mainz Group. In this talk we will provide a scenario that could account for the evaluated cross section by assuming a coherent state of the neutrino sea, which would result much lower temperature than the prediction from the standard big bang cosmology.
NOvA and T2K: The Race for the neutrino mass hierarchy
Mena, Olga; Nunokawa, Hiroshi; Parke, Stephen J.; /Fermilab
2006-09-01
The determination of the ordering of the neutrino masses (the hierarchy) is probably a crucial prerequisite to understand the origin of lepton masses and mixings and to establish their relationship to the analogous properties in the quark sector. Here, we follow an alternative strategy to the usual neutrino-antineutrino comparison in long baseline neutrino oscillation experiments: we exploit the combination of the neutrino-only data from the NOvA and the T2K experiments by performing these two off-axis experiments at different distances but at the same
NASA Astrophysics Data System (ADS)
Yin, Peng; Fan, Xiaohua; Dong, Jianmin; Guo, Wenmei; Zuo, Wei
2017-05-01
The neutrino emissivities in β-stable neutron star matter from the direct Urca (DU) processes and the modified Urca (MU) processes have been investigated by adopting 26 Skyrme interactions. Several physical quantities related to the MU processes and the DU processes have been calculated and discussed. The model-dependence of the neutrino emissivities from the DU processes is found to stem mainly from the model-dependence of the effective mass, while the neutrino emissivities from the MU processes are determined by the competition between the effects of the symmetry energy and the effective mass. Besides, we have investigated the total neutrino luminosities of neutron stars, with the masses of 1.2 , 1.4 , 1.6 and 1.8M⊙, from the DU processes and the MU processes. The neutrino luminosity of a neutron star is found to be primarily determined by whether the electron DU process is allowed or not. As long as the electron DU process can occur, the total luminosity turns out to be 5 to 8 orders of magnitude larger as compared with the case that the DU process is forbidden, which indicates that the strongest model-dependence of the neutrino luminosity comes from that of the symmetry energy and the equation of state (EOS) of neutron star matter. In the case that the DU processes are allowed, the discrepancy of the calculated neutrino luminosity using various Skyrme interactions remains noticeable, which is essentially attributed to the model-dependence of the symmetry energy, the EOS of NS matter and the effective masses.
NASA Astrophysics Data System (ADS)
Nayak, Bidyut Prava; Parida, Mina Ketan
2015-05-01
The dominance of Type-II seesaw mechanism for the neutrino masses has attracted considerable attention because of a number of advantages. We show a novel approach to achieve Type-II seesaw dominance in non-supersymmetric SO(10) grand unification where a low-mass boson and specific patterns of right-handed neutrino masses are predicted within the accessible energy range of the Large Hadron Collider. In spite of the high value of the seesaw scale, - GeV, the model predicts new dominant contributions to neutrino-less double beta decay in the - channel close to the current experimental limits via exchanges of heavier singlet fermions used as essential ingredients of this model even when the light active neutrino masses are normally hierarchical or invertedly hierarchical. We obtain upper bounds on the lightest sterile neutrino mass GeV, GeV and GeV for normally hierarchical, invertedly hierarchical and quasi-degenerate patterns of light-neutrino masses, respectively. The underlying non-unitarity effects lead to lepton flavour violating decay branching ratios within the reach of ongoing or planned experiments and the leptonic CP-violation parameter nearly two order larger than the quark sector. Some of the predicted values on the proton lifetime for are found to be within the currently accessible search limits. Other aspects of model applications including leptogenesis etc. are briefly indicated.
Sterile particles from the flavor gauge model of masses
NASA Astrophysics Data System (ADS)
Smetana, Adam
2013-04-01
Our motivation is to study a dynamics which has the ambition to underlie models of the electroweak symmetry breaking via the condensation of known fermions. The right-handed neutrinos and the seesaw mechanism are necessary ingredients for viability of this scenario. The existence of right-handed neutrinos follows from theoretical consistence of a model based on dynamical flavor gauge symmetry breaking. The model is defined by a particular flavor representation setting of electroweakly charged fermions. Only finite number of versions of the model exists. They differ by the number and the flavor structure of the right-handed neutrino sector. We choose for inspection one of them, the non-minimal version with right-handed neutrinos in one sextet and four anti-triplet flavor representations. We show that a Majorana pairing of the sextet right-handed neutrinos is responsible for the flavor symmetry breaking and for the seesaw pattern of the neutrino mass matrix. The dynamically generated neutrino mass matrix spontaneously breaks the lepton number and the chiral sterility symmetry of the right-handed neutrino sector. As a result, a spectrum of majorons, neutrino composites, manifests. We study main characteristics of both massive sterile neutrinos and majorons.
Structures of the neutrino mass spectrum and of lepton mixing as results of mirror-symmetry breaking
NASA Astrophysics Data System (ADS)
Dyatlov, I. T.
2017-07-01
The mechanism of broken mirror symmetry may be the reason behind the appearance of the observed weak-mixing matrix for leptons that has a structure involving virtually no visible regularities (flavor riddle). Special features of the Standard Model such as the particle-mass hierarchy and the neutrino spectrum deviating from the hierarchy prove here to be necessary conditions for reproducing a structure of this type. The inverse character of the neutrino spectrum and a small value of the mass m 3 are also mandatory. The smallness of the angle θ 13 is due precisely to the smallness of the mass ratios in the hierarchical lepton spectrum. The emergence of distinctions between the neutrino spectrum and the spectra of other Standard Model fermions is explained. The inverse character of the neutrino spectrum and the observed value of θ 13 make it possible to estimate the absolute values of their masses as m 1 ≈ m 2 ≈ 0.05 eV and m 3 ≈ 0.01 eV.
Neutrino fluxes from nonuniversal Higgs mass LSP annihilations in the Sun
Ellis, John; Olive, Keith A.; Savage, Christopher; Spanos, Vassilis C.
2011-04-15
We extend our previous studies of the neutrino fluxes expected from neutralino LSP annihilations inside the Sun to include variants of the minimal supersymmetric extension of the Standard Model (MSSM) with squark, slepton and gaugino masses constrained to be universal at the GUT scale, but allowing one or two nonuniversal supersymmetry breaking parameters contributing to the Higgs masses (NUHM1,2). As in the constrained MSSM (CMSSM) with universal Higgs masses, there are large regions of the NUHM parameter space where the LSP density inside the Sun is not in equilibrium, so that the annihilation rate may be far below the capture rate, and there are also large regions where the capture rate is not dominated by spin-dependent LSP-proton scattering. The spectra possible in the NUHM are qualitatively similar to those in the CMSSM. We calculate neutrino-induced muon fluxes above a threshold energy of 10 GeV, appropriate for the IceCube/DeepCore detector, for points where the NUHM yields the correct cosmological relic density for representative choices of the NUHM parameters. We find that the IceCube/DeepCore detector can probe regions of the NUHM parameter space in addition to analogues of the focus point strip and the tip of the coannihilation strip familiar from the CMSSM. These include regions with enhanced Higgsino-gaugino mixing in the LSP composition, that occurs where neutralino mass eigenstates cross over. On the other hand, rapid-annihilation funnel regions in general yield neutrino fluxes that are unobservably small.
Kayser, Boris
2012-06-01
To complement the neutrino-physics lectures given at the 2011 International School on Astro Particle Physics devoted to Neutrino Physics and Astrophysics (ISAPP 2011; Varenna, Italy), at the 2011 European School of High Energy Physics (ESHEP 2011; Cheila Gradistei, Romania), and, in modified form, at other summer schools, we present here a written description of the physics of neutrino oscillation. This description is centered on a new way of deriving the oscillation probability. We also provide a brief guide to references relevant to topics other than neutrino oscillation that were covered in the lectures. Neutrinos and photons are by far the most abundant elementary particles in the universe. Thus, if we would like to comprehend the universe, we must understand the neutrinos. Of course, studying the neutrinos is challenging, since the only known forces through which these electrically-neutral leptons interact are the weak force and gravity. Consequently, interactions of neutrinos in a detector are very rare events, so that very large detectors and intense neutrino sources are needed to make experiments feasible. Nevertheless, we have confirmed that the weak interactions of neutrinos are correctly described by the Standard Model (SM) of elementary particle physics. Moreover, in the last 14 years, we have discovered that neutrinos have nonzero masses, and that leptons mix. These discoveries have been based on the observation that neutrinos can change from one 'flavor' to another - the phenomenon known as neutrino oscillation. We shall explain the physics of neutrino oscillation, deriving the probability of oscillation in a new way. We shall also provide a very brief guide to references that can be used to study some major neutrino-physics topics other than neutrino oscillation.
State of physics at the end of the 20. century: Massive neutrinos?
Slansky, R.
1997-10-01
A brief review of neutrino masses is presented with focus on how masses might appear in unified models. A fall 1996 status report of the LSND (Liquid Scintillator Neutrino Detector) experiment at Los Alamos is given; the statistical evidence for neutrino oscillations is becoming stronger. A summary of a unified model based on SO(18) shows possible complications in understanding neutrino masses.
NASA Astrophysics Data System (ADS)
Winter, K.; Murdin, P.
2000-11-01
Neutrinos are electrically neutral ELEMENTARY PARTICLES which experience only the weak nuclear force and gravity. Their existence was introduced as a hypothesis by Wolfgang Pauli in 1930 to explain the apparent violation of energy conservation in radioactive beta decay. Chadwick had discovered in 1914 that the energy spectrum of electrons emitted in beta decay was not monoenergetic but continuous...
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; Boehnlein, D J; Bogert, D; Cavanaugh, S; Cherdack, D; Childress, S; Choudhary, B C; Coelho, J A B; Coleman, S J; Corwin, L; Cronin-Hennessy, D; Danko, I Z; de Jong, J K; Devenish, N E; Diwan, M V; Dorman, M; Escobar, C O; Evans, J J; Falk, E; Feldman, G J; Frohne, M V; Gallagher, H R; Gomes, R A; Goodman, M C; Gouffon, P; Graf, N; Gran, R; Grant, N; Grzelak, K; Habig, A; Harris, D; Hartnell, J; Hatcher, R; Himmel, A; Holin, A; Huang, X; Hylen, J; Ilic, J; Irwin, G M; Isvan, Z; Jaffe, D E; James, C; Jensen, D; Kafka, T; Kasahara, S M S; Koizumi, G; Kopp, S; Kordosky, M; Kreymer, A; Lang, K; Lefeuvre, G; Ling, J; Litchfield, P J; Litchfield, R P; Loiacono, L; Lucas, P; Mann, W A; Marshak, M L; Mayer, N; McGowan, A M; Mehdiyev, R; Meier, J R; Messier, M D; Michael, D G; Miller, W H; Mishra, S R; Mitchell, J; Moore, C D; Morfín, J; Mualem, L; Mufson, S; Musser, J; Naples, D; Nelson, J K; Newman, H B; Nichol, R J; Nowak, J A; Oliver, W P; Orchanian, M; Ospanov, R; Paley, J; Patterson, R B; Pawloski, G; Pearce, G F; Petyt, D A; Phan-Budd, S; Plunkett, R K; Qiu, X; Ratchford, J; Raufer, T M; Rebel, B; Rodrigues, P A; Rosenfeld, C; Rubin, H A; Sanchez, M C; Schneps, J; Schreiner, P; Shanahan, P; Smith, C; Sousa, A; Stamoulis, P; Strait, M; Tagg, N; Talaga, R L; Thomas, J; Thomson, M A; Tinti, G; Toner, R; Tzanakos, G; Urheim, J; Vahle, P; Viren, B; Weber, A; Webb, R C; White, C; Whitehead, L; Wojcicki, S G; Yang, T; Zwaska, R
2011-05-06
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 7.25×10(20) protons on target. A fit to neutrino oscillations yields values of |Δm(2)|=(2.32(-0.08)(+0.12))×10(-3) eV(2) for the atmospheric mass splitting and sin(2)(2θ)>0.90 (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.
Measurement of the Neutrino Mass Splitting and Flavor Mixing by MINOS
Adamson, P.
2011-05-01
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 x 10$^{20}$ protons on target. A fit to neutrino oscillations yields values of |Δm$^{2}$| = (2.32$^{+0.12}_{-0.08}$) x 10$^{-3}$ eV$^{2}$ for the atmospheric mass splitting and sin $^{2}$(2θ) > 0.90 (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.
The new discussion of a neutrino mass and issues in the formation of large-scale structure
NASA Technical Reports Server (NTRS)
Melott, Adrian L.
1991-01-01
It is argued that the discrepancy between the large-scale structure predicted by cosmological models with neutrino mass (hot dark matter) do not differ drastically from the observed structure. Evidence from the correlation amplitude, nonlinearity and the onset of galaxy formation, large-scale streaming velocities, and the topology of large-scale structure is considered. Hot dark matter models seem to be as accurate predictors of the large-scale structure as are cold dark matter models.
Lepton portal limit of inert Higgs doublet dark matter with radiative neutrino mass
NASA Astrophysics Data System (ADS)
Borah, Debasish; Sadhukhan, Soumya; Sahoo, Shibananda
2017-08-01
We study an extension of the Inert Higgs Doublet Model (IHDM) by three copies of right handed neutrinos and heavy charged leptons such that both the inert Higgs doublet and the heavy fermions are odd under the Z2 symmetry of the model. The neutrino masses are generated at one loop in the scotogenic fashion. Assuming the neutral scalar of the inert Higgs to be the dark matter candidate, we particularly look into the region of parameter space where dark matter relic abundance is primarily governed by the inert Higgs coupling with the leptons. This corresponds to tiny Higgs portal coupling of dark matter as well as large mass splitting within different components of the inert Higgs doublet suppressing the coannihilations. Such lepton portal couplings can still produce the correct relic abundance even if the Higgs portal couplings are arbitrarily small. Such tiny Higgs portal couplings may be responsible for suppressed dark matter nucleon cross section as well as tiny invisible branching ratio of the standard model Higgs, to be probed at ongoing and future experiments. We also briefly discuss the collider implications of such a scenario.
Effects of non-standard neutrino emission on the evolution of low-mass stars
NASA Astrophysics Data System (ADS)
Arceo-Díaz, S.; Schröder, K.-P.; Jack, D.; Zuber, K.
2014-10-01
Using the {Pools et al. (1995)} version of the STARS code with updated numerical tables for neutrino plasmon decay ({Kantor et al. 2007}), along with the reinterpretation of the Reimers mass-loss prescription by {Schröder et al. (2005)}, we analyze the consequences of enhanced neutrino emission on the internal structure and late evolution of the degenerated cores in low-mass stars, the non-standard increase in tip-RGB luminosity and the impact on the calibration of the Reimers mass-loss mechanism and the changes driven in post-RGB phases. With synthetic spectra generated with the PHOENIX code {Baron & Hauschildt et al. (1997)}, we also study the dependence of the non-standard increase in brightness on the selected NIR photometric band. By comparing our stellar evolutionary models with the synthetic spectra and the photometric data base of ω-Cen by {Sollima et al. (2004)}, we find the limit value μ_{ν}≤ 2.2× 10^{-12}μ_{B}.
Singlet-doublet fermionic dark matter, neutrino mass, and collider signatures
NASA Astrophysics Data System (ADS)
Bhattacharya, Subhaditya; Sahoo, Nirakar; Sahu, Narendra
2017-08-01
We propose a minimal extension of the standard model by including a scalar triplet with hypercharge 2 and two vectorlike leptons, one doublet and a singlet, to explain simultaneously the nonzero neutrino mass and dark matter (DM) content of the Universe. The DM emerges as a mixture of the neutral component of the vectorlike lepton doublet and singlet, being odd under a discrete Z2 symmetry. After electroweak symmetry breaking the triplet scalar gets an induced vacuum expectation value, which gives Majorana masses not only to the light neutrinos but also to the DM. Because of the Majorana mass of DM, the Z mediated elastic scattering with nucleon is forbidden. However, the Higgs boson mediated direct detection cross section of the DM gives an excellent opportunity to probe it at Xenon1T. The DM cannot be detected at the collider. However, the charged partner of the DM (often next-to-lightest stable particle) can give large displaced vertex signature at the Large Hadron Collider.
Assessment of molecular effects on neutrino mass measurements from tritium β decay
NASA Astrophysics Data System (ADS)
Bodine, L. I.; Parno, D. Â. S.; Robertson, R. Â. G. Â. H.
2015-03-01
The β decay of molecular tritium currently provides the highest sensitivity in laboratory-based neutrino mass measurements. The upcoming Karlsruhe Tritium Neutrino (KATRIN) experiment will improve the sensitivity to 0.2 eV, making a percent-level quantitative understanding of molecular effects essential. The modern theoretical calculations available for neutrino mass experiments agree with spectroscopic data. Moreover, when neutrino mass experiments performed in the 1980s with gaseous tritium are reevaluated using these modern calculations, the extracted neutrino mass squared values are consistent with zero instead of being significantly negative. However, the calculated molecular final-state branching ratios are in conflict with dissociation experiments performed in the 1950s. We reexamine the theory of the final-state spectrum of molecular-tritium decay and its effect on the determination of the neutrino mass, with an emphasis on the role of the vibrational- and rotational-state distribution in the ground electronic state. General features can be reproduced quantitatively from considerations of kinematics and zero-point motion. We summarize the status of validation efforts and suggest means for resolving the apparent discrepancy in dissociation rates.
Low mass binary neutron star mergers : gravitational waves and neutrino emission
NASA Astrophysics Data System (ADS)
Foucart, Francois; SXS Collaboration Collaboration
2016-03-01
We present numerical simulations of low mass binary neutron star mergers (1 . 2M⊙ - 1 . 2M⊙) with the SpEC code for a set of three nuclear-theory based, finite temperature equations of state. The merger remnant is a massive neutron star which is either permanently stable or long-lived. We focus on the post-merger gravitational wave signal, and on neutrino-matter interactions in the merger remnant. We show that the frequency peaks of the post-merger gravitational wave signal are in good agreement with predictions obtained from simulations using a simpler treatment of gravity. We then estimate the neutrino emission of the remnant using a neutrino leakage scheme and, in one case, compare these results with a gray two-moment neutrino transport scheme. We confirm the complex geometry of the neutrino emission, also observed in previous simulations with neutrino leakage, and show explicitly the presence of important differences in the neutrino luminosity, disk composition, and outflow properties between the neutrino leakage and transport schemes. We discuss the impact of our results on our ability to measure the neutron star equation of state, and on the post-merger electromagnetic signal and r-process nucleosynthesis in neutron star mergers. Einstein Fellow.
Fogli, G. L.; Lisi, E.; Marrone, A.; Melchiorri, A.; Serra, P.; Palazzo, A.; Silk, J.; Slosar, A.
2007-03-01
In the light of recent neutrino oscillation and nonoscillation data, we revisit the phenomenological constraints applicable to three observables sensitive to absolute neutrino masses: The effective neutrino mass in single beta decay (m{sub {beta}}); the effective Majorana neutrino mass in neutrinoless double beta decay (m{sub {beta}}{sub {beta}}); and the sum of neutrino masses in cosmology ({sigma}). In particular, we include the constraints coming from the first Main Injector Neutrino Oscillation Search (MINOS) data and from the Wilkinson Microwave Anisotropy Probe (WMAP) three-year (3y) data, as well as other relevant cosmological data and priors. We find that the largest neutrino squared mass difference is determined with a 15% accuracy (at 2{sigma}) after adding MINOS to world data. We also find upper bounds on the sum of neutrino masses {sigma} ranging from {approx}2 eV (WMAP-3y data only) to {approx}0.2 eV (all cosmological data) at 2{sigma}, in agreement with previous studies. In addition, we discuss the connection of such bounds with those placed on the matter power spectrum normalization parameter {sigma}{sub 8}. We show how the partial degeneracy between {sigma} and {sigma}{sub 8} in WMAP-3y data is broken by adding further cosmological data, and how the overall preference of such data for relatively high values of {sigma}{sub 8} pushes the upper bound of {sigma} in the sub-eV range. Finally, for various combination of data sets, we revisit the (in)compatibility between current {sigma} and m{sub {beta}}{sub {beta}} constraints (and claims), and derive quantitative predictions for future single and double beta decay experiments.
Matter Effects on Neutrino Oscillations in Different Supernova Models
NASA Astrophysics Data System (ADS)
Xu, Jing; Hu, Li-Jun; Li, Rui-Cheng; Guo, Xin-Heng; Young, Bing-Lin
2016-04-01
In recent years, with the development of simulations about supernova explosion, we have a better understanding about the density profiles and the shock waves in supernovae than before. There might be a reverse shock wave, another sudden change of density except the forward shock wave, or even no shock wave, emerging in the supernova. Instead of using the expression of the crossing probability at the high resonance, PH, we have studied the matter effects on neutrino oscillations in different supernova models. In detail, we have calculated the survival probability of ve (Ps) and the conversion probability of vx (Pc) in the Schrödinger equation within a simplified two-flavor framework for a certain case, in which the neutrino transfers through the supernova matter from an initial flavor eigenstate located at the core of the supernova. Our calculations was based on the data of density in three different supernova models obtained from simulations. In our work, we do not steepen the density gradient around the border of the shock wave, which differs to what was done in most of the other simulations. It is found that the mass and the density distribution of the supernova do make a difference on the behavior of Ps and Pc. With the results of Ps and Pc, we can estimate the number of ve (and vx) remained in the beam after they go through the matter in the supernova. Supported by National Science Foundation of China under Grant Nos. 11175020 and 11275025
Measurement of the Top Quark Mass in Dilepton Final States with the Neutrino Weighting Method
Ilchenko, Yuriy
2012-12-15
The top quark is the heaviest fundamental particle observed to date. The mass of the top quark is a free parameter in the Standard Model (SM). A precise measurement of its mass is particularly important as it sets an indirect constraint on the mass of the Higgs boson. It is also a useful constraint on contributions from physics beyond the SM and may play a fundamental role in the electroweak symmetry breaking mechanism. I present a measurement of the top quark mass in the dilepton channel using the Neutrino Weighting Method. The data sample corresponds to an integrated luminosity of 4.3 fb^{-1} of p$\\bar{p}$ collisions at Tevatron with √s = 1.96 TeV, collected with the DØ detector. Kinematically under-constrained dilepton events are analyzed by integrating over neutrino rapidity. Weight distributions of t$\\bar{t}$ signal and background are produced as a function of the top quark mass for different top quark mass hypotheses. The measurement is performed by constructing templates from the moments of the weight distributions and input top quark mass, followed by a subsequent likelihood t to data. The dominant systematic uncertainties from jet energy calibration is reduced by using a correction from `+jets channel. To replicate the quark avor dependence of the jet response in data, jets in the simulated events are additionally corrected. The result is combined with our preceding measurement on 1 fb^{-1} and yields m_{t} = 174.0± 2.4 (stat.) ±1.4 (syst.) GeV.
NASA Astrophysics Data System (ADS)
Huang, Yong-Chang; Tehreem Iqbal, Syeda; Lei, Zhen; Wang, Wen-Yu
2017-04-01
The masses of the three generations of charged leptons are known to completely satisfy Koide’s mass relation, but the question remains of whether such a relation exists for neutrinos. In this paper, by considering the seesaw mechanism as the mechanism generating tiny neutrino masses, we show how neutrinos satisfy Koide’s mass relation, on the basis of which we systematically give exact values of both left- and right-handed neutrino masses. Supported by National Natural Science Foundation of China (11275017, 11172008, 11173028). STI has the financial support from Chinese Scholarship Council
Light sterile neutrino and dark matter in left-right symmetric models without a Higgs bidoublet
NASA Astrophysics Data System (ADS)
Borah, Debasish
2016-10-01
We present a class of left-right symmetric models where Dirac as well as Majorana mass terms of neutrinos can arise at the one-loop level in a scotogenic fashion: with dark matter particles going inside the loop. We show the possibility of naturally light right-handed neutrinos that can have interesting implications for neutrinoless double beta decay experiments as well as cosmology. Apart from a stable dark matter candidate stabilized by a remnant Z2 symmetry, one can also have a long-lived keV sterile neutrino dark matter in these models. This class of models can have very different collider signatures compared to the conventional left-right models.
NASA Astrophysics Data System (ADS)
Parida, M. K.; Nayak, Bidyut Prava; Satpathy, Rajesh; Awasthi, Ram Lal
2017-04-01
We discuss gauge coupling unification of SU(3) C × SU(2) L × U(1) Y descending directly from non-supersymmetric SO(10) while providing solutions to the three out-standing problems of the standard model: neutrino masses, dark matter, and the baryon asymmetry of the universe. Conservation of matter parity as gauged discrete symmetry for the stability and identification of dark matter in the model calls for high-scale spontaneous symmetry breaking through 126 H Higgs representation. This naturally leads to the hybrid seesaw formula for neutrino masses mediated by heavy scalar triplet and right-handed neutrinos. Being quadratic in the Majorana coupling, the seesaw formula predicts two distinct patterns of right-handed neutrino masses, one hierarchical and another not so hierarchical (or compact), when fitted with the neutrino oscillation data. Predictions of the baryon asymmetry via leptogenesis are investigated through the decays of both the patterns of RH ν masses. A complete flavor analysis has been carried out to compute CP-asymmetries including washouts and solutions to Boltzmann equations have been utilised to predict the baryon asymmetry. The additional contribution to vertex correction mediated by the heavy left-handed triplet scalar is noted to contribute as dominantly as other Feynman diagrams. We have found successful predictions of the baryon asymmetry for both the patterns of right-handed neutrino masses. The SU(2) L triplet fermionic dark matter at the TeV scale carrying even matter parity is naturally embedded into the non-standard fermionic representation 45 F of SO(10). In addition to the triplet scalar and the triplet fermion, the model needs a nonstandard color octet fermion of mass ˜ 5 × 107 GeV to achieve precision gauge coupling unification at the GUT mass scale M U 0 = 1015.56 GeV. Threshold corrections due to superheavy components of 126H and other representations are estimated and found to be substantial. It is noted that the proton life
Atmospheric neutrinos and discovery of neutrino oscillations
Kajita, Takaaki
2010-01-01
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. PMID:20431258
Atmospheric neutrinos and discovery of neutrino oscillations.
Kajita, Takaaki
2010-01-01
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.
Experimental conditions for determination of the neutrino mass hierarchy with reactor antineutrinos
NASA Astrophysics Data System (ADS)
Pac, Myoung Youl
2016-01-01
This article reports the optimized experimental requirements to determine neutrino mass hierarchy using electron antineutrinos (νbare) generated in a nuclear reactor. The features of the neutrino mass hierarchy can be extracted from the | Δ m312 | and | Δ m322 | oscillations by applying the Fourier sine and cosine transforms to the L / E spectrum. To determine the neutrino mass hierarchy above 90% probability, the requirements on the energy resolution as a function of the baseline are studied at sin2 2θ13 = 0.1. If the energy resolution of the neutrino detector is less than 0.04 /√{Eν} and the determination probability obtained from Bayes' theorem is above 90%, the detector needs to be located around 48-53 km from the reactor(s) to measure the energy spectrum of νbare. These results will be helpful for setting up an experiment to determine the neutrino mass hierarchy, which is an important problem in neutrino physics.
Extended scaling and residual flavor symmetry in the neutrino Majorana mass matrix
NASA Astrophysics Data System (ADS)
Samanta, Rome; Roy, Probir; Ghosal, Ambar
2016-12-01
The residual symmetry approach, along with a complex extension for some flavor invariance, is a powerful tool to uncover the flavor structure of the 3 × 3 neutrino Majorana mass matrix M_ν toward gaining insights into neutrino mixing. We utilize this to propose a complex extension of the real scaling ansatz for M_ν which was introduced some years ago. Unlike the latter, our proposal allows a nonzero mass for each of the three light neutrinos as well as a nonvanishing θ _{13}. The generation of light neutrino masses via the type-I seesaw mechanism is also demonstrated. A major result of this scheme is that leptonic Dirac CP-violation must be maximal while atmospheric neutrino mixing does not need to be exactly maximal. Moreover, each of the two allowed Majorana phases, to be probed by the search for nuclear 0ν β β decay, has to be at one of its two CP-conserving values. There are other interesting consequences such as the allowed occurrence of a normal mass ordering which is not favored by the real scaling ansatz. Our predictions will be tested in ongoing and future neutrino oscillation experiments at T2K, NOν A and DUNE.
KM3NeT - ORCA: measuring the neutrino mass ordering in the Mediterranean
NASA Astrophysics Data System (ADS)
Kouchner, Antoine
2016-05-01
ORCA (Oscillations Research with Cosmics in the Abyss) is the low-energy branch of KM3NeT, the underwater Cherenkov neutrino detector in the Mediterranean. Its primary goal is to resolve the long-standing unsolved question of the neutrino mass ordering by measuring matter oscillation effects in atmospheric neutrinos. To be deployed at the French KM3NeT site, ORCA’s multi-PMT optical modules will exploit the excellent optical properties of deep seawater to reconstruct cascade and track events with a few GeV of energy. This contribution reviews the methods and technology, and discusses the current expected performances.
Neutrino sector with Majorana mass terms and Friedberg-Lee symmetry
NASA Astrophysics Data System (ADS)
Jarlskog, C.
2008-04-01
We examine a recently proposed symmetry/condition by Friedberg and Lee in a framework where three right-handed neutrinos are added to the spectrum of the three-family minimal standard model. It is found that the right-handed neutrinos are very special, with respect to this symmetry. In the symmetry limit the neutrinos are massless, which could possibly be a hint about why they are light. Imposed as a condition and not as a full symmetry, we find that one of the three right-handed neutrinos simply decouples (has only gravitational interactions) and one of the interacting neutrinos is massless. The possible relation of the model to the seesaw mechanism is briefly discussed.
Two loop neutrino model and dark matter particles with global B−L symmetry
Baek, Seungwon; Okada, Hiroshi; Toma, Takashi E-mail: hokada@kias.re.kr
2014-06-01
We study a two loop induced seesaw model with global U(1){sub B−L} symmetry, in which we consider two component dark matter particles. The dark matter properties are investigated together with some phenomenological constraints such as electroweak precision test, neutrino masses and mixing and lepton flavor violation. In particular, the mixing angle between the Standard Model like Higgs and an extra Higgs is extremely restricted by the direct detection experiment of dark matter. We also discuss the contribution of Goldstone boson to the effective number of neutrino species ΔN{sub eff} ≈ 0.39 which has been reported by several experiments.
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.
Cosmology favoring extra radiation and sub-eV mass sterile neutrinos as an option.
Hamann, Jan; Hannestad, Steen; Raffelt, Georg G; Tamborra, Irene; Wong, Yvonne Y Y
2010-10-29
Precision cosmology and big-bang nucleosynthesis mildly favor extra radiation in the Universe beyond photons and ordinary neutrinos, lending support to the existence of low-mass sterile neutrinos. We use the WMAP 7-year data, small-scale cosmic microwave background observations from ACBAR, BICEP, and QuAD, the SDSS 7th data release, and measurement of the Hubble parameter from HST observations to derive credible regions for the assumed common mass scale m{s} and effective number N{s} of thermally excited sterile neutrino states. Our results are compatible with the existence of one or perhaps two sterile neutrinos, as suggested by LSND and MiniBooNE, if m{s} is in the sub-eV range.
Correlation mass method for analysis of neutrinos from supernova 1987A
NASA Technical Reports Server (NTRS)
Chiu, Hong-Yee; Chan, Kwing L.; Kondo, Yoji
1988-01-01
Application of a time-energy correlation method to the Kamiokande II (KII) observations of neutrinos apparently emitted from supernova 1987A has yielded a neutrino rest mass of 3.6 eV. A Monte Carlo analysis shows a reconfirming probabilty distribution for the neutrino rest mass peaked at 2.8, and dropping to 50 percent of the peak at 1.4 and 4.8 eV. Although the KII data indicate a very short time scale of emission, over an extended period on the order of 10 sec, both data from the Irvine-Michigan-Brookhaven experiment and the KII data show a tendency for the more energetic neutrinos to be emitted earlier at the source, suggesting the possibility of cooling.
Status and prospects of global analyses of neutrino mass-mixing parameters
NASA Astrophysics Data System (ADS)
Capozzi, F.; Lisi, E.; Marrone, A.; Montanino, D.; Palazzo, A.
2017-09-01
We discuss the present knowledge of the neutrino oscillation parameters, the two mass squared differences (δm 2, Δm 2), the three mixing angles (θ 12, θ 13, 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 θ 23 and the neutrino mass ordering are still undetermined. We update our previous analysis, by adding to the global fit the recent results presented at The XXVII International Conference on Neutrino Physics and Astrophysics (Neutrino 2016) by the experiments T2K, NOνA, Super-Kamiokande, Daya Bay and RENO.
Absolute mass of neutrinos and the first unique forbidden β decay of Re187
NASA Astrophysics Data System (ADS)
Dvornický, Rastislav; Muto, Kazuo; Šimkovic, Fedor; Faessler, Amand
2011-04-01
The planned rhenium β-decay experiment, called the “Microcalorimeter Arrays for a Rhenium Experiment” (MARE), might probe the absolute mass scale of neutrinos with the same sensitivity as the Karlsruhe tritium neutrino mass (KATRIN) experiment, which will take commissioning data in 2011 and will proceed for 5 years. We present the energy distribution of emitted electrons for the first unique forbidden β decay of Re187. It is found that the p-wave emission of electron dominates over the s wave. By assuming mixing of three neutrinos, the Kurie function for the rhenium β decay is derived. It is shown that the Kurie plot near the end point is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed β decay of H3.
Absolute mass of neutrinos and the first unique forbidden {beta} decay of {sup 187}Re
Dvornicky, Rastislav; Simkovic, Fedor; Muto, Kazuo; Faessler, Amand
2011-04-15
The planned rhenium {beta}-decay experiment, called the ''Microcalorimeter Arrays for a Rhenium Experiment'' (MARE), might probe the absolute mass scale of neutrinos with the same sensitivity as the Karlsruhe tritium neutrino mass (KATRIN) experiment, which will take commissioning data in 2011 and will proceed for 5 years. We present the energy distribution of emitted electrons for the first unique forbidden {beta} decay of {sup 187}Re. It is found that the p-wave emission of electron dominates over the s wave. By assuming mixing of three neutrinos, the Kurie function for the rhenium {beta} decay is derived. It is shown that the Kurie plot near the end point is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed {beta} decay of {sup 3}H.
Cosmology Favoring Extra Radiation and Sub-eV Mass Sterile Neutrinos as an Option
Hamann, Jan; Hannestad, Steen; Raffelt, Georg G.; Tamborra, Irene; Wong, Yvonne Y. Y.
2010-10-29
Precision cosmology and big-bang nucleosynthesis mildly favor extra radiation in the Universe beyond photons and ordinary neutrinos, lending support to the existence of low-mass sterile neutrinos. We use the WMAP 7-year data, small-scale cosmic microwave background observations from ACBAR, BICEP, and QuAD, the SDSS 7th data release, and measurement of the Hubble parameter from HST observations to derive credible regions for the assumed common mass scale m{sub s} and effective number N{sub s} of thermally excited sterile neutrino states. Our results are compatible with the existence of one or perhaps two sterile neutrinos, as suggested by LSND and MiniBooNE, if m{sub s} is in the sub-eV range.
Correlation mass method for analysis of neutrinos from supernova 1987A
NASA Technical Reports Server (NTRS)
Chiu, Hong-Yee; Chan, Kwing L.; Kondo, Yoji
1988-01-01
Application of a time-energy correlation method to the Kamiokande II (KII) observations of neutrinos apparently emitted from supernova 1987A has yielded a neutrino rest mass of 3.6 eV. A Monte Carlo analysis shows a reconfirming probabilty distribution for the neutrino rest mass peaked at 2.8, and dropping to 50 percent of the peak at 1.4 and 4.8 eV. Although the KII data indicate a very short time scale of emission, over an extended period on the order of 10 sec, both data from the Irvine-Michigan-Brookhaven experiment and the KII data show a tendency for the more energetic neutrinos to be emitted earlier at the source, suggesting the possibility of cooling.
EFFECTS OF THE NEUTRINO MASS SPLITTING ON THE NONLINEAR MATTER POWER SPECTRUM
Wagner, Christian; Verde, Licia; Jimenez, Raul
2012-06-20
We have performed cosmological N-body simulations which include the effect of the masses of the individual neutrino species. The simulations were aimed at studying the effect of different neutrino hierarchies on the matter power spectrum. Compared to the linear theory predictions, we find that nonlinearities enhance the effect of hierarchy on the matter power spectrum at mildly nonlinear scales. The maximum difference between the different hierarchies is about 0.5% for a sum of neutrino masses of 0.1 eV. Albeit this is a small effect, it is potentially measurable from upcoming surveys. In combination with neutrinoless double-{beta} decay experiments, this opens up the possibility of using the sky to determine if neutrinos are Majorana or Dirac fermions.
Anatomy of Higgs mass in supersymmetric inverse seesaw models
NASA Astrophysics Data System (ADS)
Chun, Eung Jin; Mummidi, V. Suryanarayana; Vempati, Sudhir K.
2014-09-01
We compute the one loop corrections to the CP-even Higgs mass matrix in the supersymmetric inverse seesaw model to single out the different cases where the radiative corrections from the neutrino sector could become important. It is found that there could be a significant enhancement in the Higgs mass even for Dirac neutrino masses of O(30) GeV if the left-handed sneutrino soft mass is comparable or larger than the right-handed neutrino mass. In the case where right-handed neutrino masses are significantly larger than the supersymmetry breaking scale, the corrections can utmost account to an upward shift of 3 GeV. For very heavy multi TeV sneutrinos, the corrections replicate the stop corrections at 1-loop. We further show that general gauge mediation with inverse seesaw model naturally accommodates a 125 GeV Higgs with TeV scale stops.
Axion and neutrino physics in a U (1 )-enhanced supersymmetric model
NASA Astrophysics Data System (ADS)
Ahn, Y. H.
2017-07-01
Motivated by the flavored Peccei-Quinn symmetry for unifying the flavor physics and string theory, we construct an explicit model by introducing a U (1 ) symmetry such that the U (1 )X-[gravity]2 anomaly-free condition together with the standard model flavor structure demands additional sterile neutrinos as well as no axionic domain-wall problem. Such additional sterile neutrinos play the role of realizing baryogenesis via a new Affleck-Dine leptogenesis. We provide grounds for interpreting the U (1 )X symmetry as a fundamental symmetry of nature. The model will resolve rather recent but fast-growing issues in astroparticle physics, including leptonic mixings and C P violation in neutrino oscillation, high-energy neutrinos, QCD axions, and axion cooling of stars. The QCD axion decay constant, through its connection to the astrophysical constraints of stellar evolution and the SM fermion masses, is shown to be fixed at FA=1.30-0.54+0.66×1 09 GeV (consequently, its mass is ma=4.3 4-1.49+3.37 meV and the axion-photon coupling is |ga γ γ|=1.30-0.45+1.01×10-12 GeV-1 ). Interestingly enough, we show that neutrino oscillations at low energies could be connected to astronomical-scale baseline neutrino oscillations. The model predicts the nonobservational neutrinoless double beta (0 ν β β ) decay rate as well as a remarkable pattern between the leptonic Dirac C P phase (δC P) and the atmospheric mixing angle (θ23); e.g., δC P≃22 0 ° - 24 0 ° , 120°-140° for θ23=42.3 ° for normal mass ordering, and δC P≃28 3 ° , 250°, 100°, 70° for θ23=49.5 ° for the inverted one. We stress that future measurements on the θ23, 0 ν β β decay rate, the sum of active neutrino masses, the track-to-shower ratio of a cosmic neutrino, astrophysical constraints on axions, QCD axion mass, and the axion-photon coupling are of importance to test the model in the near future.
Precision electron-capture energy in 202Pb and its relevance for neutrino mass determination
NASA Astrophysics Data System (ADS)
Welker, A.; Filianin, P.; Althubiti, N. A. S.; Atanasov, D.; Blaum, K.; Cocolios, T. E.; Eliseev, S.; Herfurth, F.; Kreim, S.; Lunney, D.; Manea, V.; Neidherr, D.; Novikov, Yu.; Rosenbusch, M.; Schweikhard, L.; Wienholtz, F.; Wolf, R. N.; Zuber, K.
2017-07-01
Within the framework of an extensive programme devoted to the search for alternative candidates for the neutrino mass determination, the atomic mass difference between 202Pb and 202Tl has been measured with the Penning trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN. The obtained value Q_{EC} = 38.8(43) keV is three times more precise than the AME2012 value. While it will probably not lead to a replacement of 163Ho in modern experiments on the determination of the electron-neutrino mass, the electron capture in 202Pb would however allow a determination of the electron-neutrino mass on the few-eV level using a cryogenic micro-calorimeter.
Meson exchange current (MEC) models in neutrino interaction generators
Katori, Teppei
2015-05-15
Understanding of the so-called 2 particle-2 hole (2p-2h) effect is an urgent program in neutrino interaction physics for current and future oscillation experiments. Such processes are believed to be responsible for the event excesses observed by recent neutrino experiments. The 2p-2h effect is dominated by the meson exchange current (MEC), and is accompanied by a 2-nucleon emission from the primary vertex, instead of a single nucleon emission from the charged-current quasi-elastic (CCQE) interaction. Current and future high resolution experiments can potentially nail down this effect. For this reason, there are world wide efforts to model and implement this process in neutrino interaction simulations. In these proceedings, I would like to describe how this channel is modeled in neutrino interaction generators.
Ugliano, Marcella; Janka, Hans-Thomas; Marek, Andreas; Arcones, Almudena
2012-09-20
We perform hydrodynamic supernova (SN) simulations in spherical symmetry for over 100 single stars of solar metallicity to explore the progenitor-explosion and progenitor-remnant connections established by the neutrino-driven mechanism. We use an approximative treatment of neutrino transport and replace the high-density interior of the neutron star (NS) by an inner boundary condition based on an analytic proto-NS core-cooling model, whose free parameters are chosen such that explosion energy, nickel production, and energy release by the compact remnant of progenitors around 20 M{sub Sun} are compatible with SN 1987A. Thus, we are able to simulate the accretion phase, initiation of the explosion, subsequent neutrino-driven wind phase for 15-20 s, and the further evolution of the blast wave for hours to days until fallback is completed. Our results challenge long-standing paradigms. We find that remnant mass, launch time, and properties of the explosion depend strongly on the stellar structure and exhibit large variability even in narrow intervals of the progenitors' zero-age main-sequence mass. While all progenitors with masses below {approx}15 M{sub Sun} yield NSs, black hole (BH) as well as NS formation is possible for more massive stars, where partial loss of the hydrogen envelope leads to weak reverse shocks and weak fallback. Our NS baryonic masses of {approx}1.2-2.0 M{sub Sun} and BH masses >6 M{sub Sun} are compatible with a possible lack of low-mass BHs in the empirical distribution. Neutrino heating accounts for SN energies between some 10{sup 50} erg and {approx}2 Multiplication-Sign 10{sup 51} erg but can hardly explain more energetic explosions and nickel masses higher than 0.1-0.2 M{sub Sun }. These seem to require an alternative SN mechanism.
Dipolar dark matter in light of the 3.5 keV x-ray line, neutrino mass, and LUX data
NASA Astrophysics Data System (ADS)
Patra, Sudhanwa; Sahoo, Nirakar; Sahu, Narendra
2015-06-01
A simple extension of the standard model (SM) providing transient magnetic moments to right-handed neutrinos is presented. In this model, the decay of the next-to-lightest right-handed heavy neutrino to the lightest one and a photon (N2→N1+γ ) can explain the ˜3.5 keV x-ray line signal observed by the XMM-Newton X-ray observatory. Beside the SM particles and heavy right-handed Majorana neutrinos, the model contains a singly charged scalar (H±) and an extra Higgs doublet (Σ ). Within this minimal set of extra fields the sub-eV masses of left-handed neutrinos are also explained. Moreover, we show that the spin-independent dark matter-nucleon cross section is compatible with the latest LUX data.
COHERENT search strategy for beyond standard model neutrino interactions
NASA Astrophysics Data System (ADS)
Shoemaker, Ian M.
2017-06-01
We study the sensitivity of the COHERENT experiment's stopped pion source of neutrinos at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory to neutrino non-standard interactions (NSI). In particular, we find that simple event counting above threshold can improve constraints on NSI for electron- and muon-flavored NSI, with the strongest constraints arising for flavor-diagonal NSI coupling to μ neutrinos. However, if the detector resolution is sufficient to all for even a coarse spectral study of events, COHERENT will also be sensitive to the mass scale of NSI. We demonstrate that this can yield new limits on Z' completions of NSI if the gauge boson mass is ≲1 GeV .
Neutrino event counts from Type Ia supernova models
NASA Astrophysics Data System (ADS)
Nagaraj, Gautam; Scholberg, Kate
2016-01-01
Core collapse supernovae (SNe) are widely known to be among the universe's primary neutrino factories, releasing ˜99% of their energy, or ˜1053 ergs, in the form of the tiny leptons. On the other hand, less than 4% of the energy of Type Ia SNe is released via neutrinos, hence making Ia SNe impossible to detect (through neutrino observations) at typical supernova distances. For this reason, neutrino signatures from these explosions have very rarely been modeled. We ran time-sliced fluences from non-oscillation pure deflagration and delayed detonation (DDT) Ia models by Odrzywolek and Plewa (2011) through SNOwGLoBES, a software that calculates event rates and other observed quantities of supernova neutrinos in various detectors. We determined Ia neutrino event rates in Hyper-K, a proposed water Cherenkov detector, JUNO, a scintillator detector under construction, and DUNE, a proposed argon detector, and identified criteria to distinguish between the two models (pure deflagration and DDT) based on data from a real supernova (statistically represented by a Poisson distribution around the expected result). We found that up to distances of 8.00, 1.54, and 2.37 kpc (subject to change based on oscillation effects and modified detector efficiencies), we can discern the explosion mechanism with ≥90% confidence in Hyper-K, JUNO, and DUNE, respectively, thus learning more about Ia progenitors.
Neutrino mass and the origin of galactic magnetic fields
Enqvist, K. ); Semikoz, V. IZMIRAN, Academy of Sciences, Troitsk 142092 ); Shukurov, A. Computing Center, Moscow University, Moscow 119899 ); Sokoloff, D. Isaac Newton Institute, Cambridge University, Cambridge CB3 0EH )
1993-11-15
We compare two constraints on the strength of the cosmological primordial magnetic field: the one following from the restrictions on the Dirac neutrino spin flip in the early Universe, and another one based on the galactic dynamo theory for the Milky Way (presuming that the seed magnetic field has a relic origin). Since the magnetic field facilitates transitions between left- and right-handed neutrino states, thereby affecting [sup 4]He production at primordial nucleosynthesis, we can obtain a guaranteed [ital upper] limit on the strength of the relic magnetic field in the protogalaxy, [ital B][sub [ital c
Hambye, Thomas; Kannike, Kristjan; Raidal, Martti; Ma, Ernest
2007-05-01
The evidence for dark matter signals a new class of particles at the TeV scale, which may manifest themselves indirectly through loop effects. In a simple model we show that these loop effects may be responsible for the enhanced muon anomalous magnetic moment, for the neutrino mass, as well as for leptogenesis in a novel way. This scenario can be verified at LHC and/or ILC experiments.
Neutrino fluctuat nec mercitur: are fossil neutrinos detectable
De Rujula, A
1980-04-01
A brief report is presented on the question whether light (few eV to approx. 100 eV) neutrinos left over from the big bang are detectable. The answer is perhaps. If the weak current of leptons, like those of quarks, are not diagonal in mass eigenstates, a neutrino will decay into a lighter neutrino and a monochromatic photon. The corresponding photon line may be detectable provided: neutrinos are heavy enough to participate in galaxy clustering and neutrino lifetimes are, as in some weak interaction models, short enough.
Kayser, Boris; /Fermilab
2005-06-01
Thanks to compelling evidence that neutrinos can change flavor, we now know that they have nonzero masses, and that leptons mix. In these lectures, we explain the physics of neutrino flavor change, both in vacuum and in matter. Then, we describe what the flavor-change data have taught us about neutrinos. Finally, we consider some of the questions raised by the discovery of neutrino mass, explaining why these questions are so interesting, and how they might be answered experimentally.
NASA Astrophysics Data System (ADS)
Böhringer, Hans; Chon, Gayoung
2016-07-01
The high precision measurements of the cosmic microwave background by the Planck survey yielded tight constraints on cosmological parameters and the statistics of the density fluctuations at the time of recombination. This provides the means for a critical study of structure formation in the Universe by comparing the microwave background results with present epoch measurements of the cosmic large-scale structure. It can reveal subtle effects such as how different forms of Dark Matter may modify structure growth. Currently most interesting is the damping effect of structure growth by massive neutrinos. Different observations of low redshift matter density fluctuations provided evidence for a signature of massive neutrinos. Here we discuss the study of the cosmic large-scale structure with a complete sample of nearby, X-ray luminous clusters from our REFLEX cluster survey. From the observed X-ray luminosity function and its reproduction for different cosmological models, we obtain tight constraints on the cosmological parameters describing the matter density, Ωm, and the density fluctuation amplitude, σ8. A comparison of these constraints with the Planck results shows a discrepancy in the framework of a pure ΛCDM model, but the results can be reconciled, if we allow for a neutrino mass in the range of 0.17 eV to 0.7 eV. Also some others, but not all of the observations of the nearby large-scale structure provide evidence or trends for signatures of massive neutrinos. With further improvement in the systematics and future survey projects, these indications will develop into a definitive measurement of neutrino masses.
Nonstandard neutrino-neutrino refractive effects in dense neutrino gases
Blennow, Mattias; Mirizzi, Alessandro; Serpico, Pasquale D.; /CERN /Fermilab
2008-10-01
We investigate the effects of nonstandard four-fermion neutrino-neutrino interactions on the flavor evolution of dense neutrino gases. We find that in the regions where the neutrino-neutrino refractive index leads to collective flavor oscillations, the presence of new neutrino interactions can produce flavor equilibration in both normal and inverted neutrino mass hierarchy. In realistic supernova environments, these effects are significant if the nonstandard neutrino-neutrino interaction strength is comparable to the one expected in the standard case, dominating the ordinary matter potential. However, very small nonstandard neutrino-neutrino couplings are enough to trigger the usual collective neutrino flavor transformations in the inverted neutrino mass hierarchy, even if the mixing angle vanishes exactly.
Probability densities of the effective neutrino masses mβ and mββ
NASA Astrophysics Data System (ADS)
Di Iura, Andrea; Meloni, Davide
2017-08-01
We compute the probability densities of the effective neutrino masses mβ and mββ using the Kernel Density Estimate (KDE) approach applied to a distribution of points in the (mmin ,mββ) and (mβ ,mββ) planes, obtained using the available Probability Distribution Functions (PDFs) of the neutrino mixing angles and mass differences, with the additional constraints coming from cosmological data on the sum of the neutrino masses. We show that the reconstructed probability densities strongly depend on the assumed set of cosmological data: for ∑jmj ≤ 0.68 eV at 95% CL a sensitive portion of the allowed values are already excluded by null results of experiments searching for mββ and mβ, whereas in the case ∑jmj ≤ 0.23 eV at 95% CL the bulk of the probability densities are below the current bounds.
Beta Decay in the Field of an Electromagnetic Wave and Experiments on Measuring the Neutrino Mass
Dorofeev, O.F.; Lobanov, A.E.
2005-06-01
Investigations of the effect of an electromagnetic wave field on the beta-decay process are used to analyze the tritium-decay experimental data on the neutrino mass. It is shown that the electromagnetic wave can distort the beta spectrum, shifting the end point to the higher energy region. This phenomenon is purely classical and it is associated with the electron acceleration in the radiation field. Since strong magnetic fields exist in setups for precise measurement of the neutrino mass, the indicated field can appear owing to the synchrotron radiation mechanism. The phenomenon under consideration can explain the experimentally observed anomalies in the spectrum of the decay electrons; in particular, the effect of the 'negative square of the neutrino mass'.
Geometry of the effective Majorana neutrino mass in the 0νββ decay
NASA Astrophysics Data System (ADS)
Xing, Zhi-zhong; Zhou, Ye-Ling
2015-01-01
The neutrinoless double-beta (0νββ) decay is a unique process used to identify the Majorana nature of massive neutrinos, and its rate depends on the size of the effective Majorana neutrino mass
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.
A gauge model for right handed neutrinos as dark matter
Hernandez-Pinto, R. J.; Perez-Lorenzana, A.
2008-07-02
We suggest a simple extension of the electroweak group, SU(2){sub L}xU(1){sub Y}xU(1){sub B-L}, where the breaking of U(1){sub B-L} symmetry provides masses for right handed neutrinos, N, at an acceptable range for them to be Dark Matter (DM). We study the contributions to Moeller and Bhabha scattering due to B-L neutral boson to constrain its gauge coupling. We analize N decay rates to determine the number of families that should be considered as DM candidates. The decoupling temperature between active and sterile neutrinos is also calculated.
A gauge model for right handed neutrinos as dark matter
NASA Astrophysics Data System (ADS)
Hernández-Pinto, R. J.; Pérez-Lorenzana, A.
2008-07-01
We suggest a simple extension of the electroweak group, SU(2)L×U(1)Y×U(1)B-L, where the breaking of U(1)B-L symmetry provides masses for right handed neutrinos, N, at an acceptable range for them to be Dark Matter (DM). We study the contributions to Mo/ller and Bhabha scattering due to B-L neutral boson to constrain its gauge coupling. We analize N decay rates to determine the number of families that should be considered as DM candidates. The decoupling temperature between active and sterile neutrinos is also calculated.
Hadronic modeling of TeV AGN: Gammas and neutrinos
NASA Astrophysics Data System (ADS)
Cerruti, M.; Zech, A.; Emery, G.; Guarin, D.
2017-01-01
Blazar emission models are usually divided into two big families, leptonic and hadronic, according to the particles which are responsible for the gamma-ray component of their spectral energy distributions. Even though leptonic models have been successful in explaining the gamma-ray emission from most blazars, hadronic models still present an intriguing alternative. They have the unique advantage to link the emission of photons, neutrinos, and cosmic rays from the astrophysical source. We have developed a stationary one-zone lepto-hadronic code to model the emission from blazars in both leptonic and hadronic scenarios. In this contribution we focus on hadronic modeling of a few selected TeV blazars of the BL Lac type and the radio galaxy Centaurus A detected by Cherenkov telescopes. We study in particular their associated neutrino emission, for different hadronic scenarios, and how it compares to the sensitivity of current neutrino detectors.
Constraints on Neutrino Masses from the Lensing Dispersion of Type Ia Supernovae
NASA Astrophysics Data System (ADS)
Hada, Ryuichiro; Futamase, Toshifumi
2016-09-01
We investigate how accurately the total mass of neutrinos is constrained from the magnitude dispersion of SNe Ia due to the effects of gravitational lensing. For this purpose, we use the propagation equation of light bundles in a realistic inhomogeneous universe and propose a sample selection for supernovae to avoid difficulties associated with small-scale effects such as strong lensing or shear effects. With a fitting formula for the nonlinear matter power spectrum taking account of the effects of massive neutrinos, we find that in our model it is possible to obtain the upper limit {{Σ }}{m}ν ≃ 1.0[{{eV}}] for future optical imaging surveys with the Wide-Field InfraRed Survey Telescope and Large Synoptic Survey Telescope. Furthermore, we discuss how far we need to observe SNe Ia and to what extent we have to reduce the magnitude error except for lensing in order to realize the current tightest limit {{Σ }}{m}ν \\lt 0.2[{{eV}}].
Neutrino physics, superbeams and the neutrino factory
Boris Kayser
2003-10-14
We summarize what has been learned about the neutrino mass spectrum and neutrino mixing, identify interesting open questions that can be answered by accelerator neutrino facilities of the future, and discuss the importance and physics of answering them.
Neutrino Oscillations, the Higgs Boson, and the Private Higgs Model
NASA Astrophysics Data System (ADS)
BenTov, Jonathan
"CESR, PEP, PETRA, ISABELLE, p-bar p colliders, LEP, the tevatron, and ep machines are at various levels of design or construction. They will study the properties of b-matter, see weak intermediaries, and perhaps find the t-quark and the Higgs boson. Never before was there such a bestiary waiting to be discovered; and what surprises will be found!" - S. L. Glashow ("The Future of Elementary Particle Physics," Quarks and Leptons, NATO Advanced Study Institutes Series Volume 61, 1980, pp 687-713) The situation in 1980 was clearly different from the present situation in 2013, in which we face the very real possibilty that no new degrees of freedom will ever again be within reach of a collider. In an intriguing twist of fate, this very fact results in a sharp paradox for fundamental physics: the Higgs mass should be MP/m h ˜ 1017 times larger than it actually is, and the vacuum energy density of the universe should be (M P/A)4 ˜ (1031)4 times larger than it actually is, and apparently nature refuses to give us any more clues as to why. These together are what I would call the main problem of 21st century physics: despite all of the predictive success of particle physics so far, we must find a way to suitably modify the rules of quantum field theory, lest we accept the unproductive defeatist attitude that our universe is simply fine-tuned. In the meantime, there is much interesting work to be done in more "traditional" particle physics: we have learned that neutrinos actually have tiny but nonzero masses, which is clear and unambiguous evidence for physics beyond the Standard Model. I will allocate the first third of this document to phenomena related to neutrino oscillations. In particular, I would like to argue that some of the apparent differences between neutrino mixing and quark mixing are to an extent illusory, and actually many aspects of the two sectors can be understood in a coherent framework for extending the Standard Model. The remaining two-thirds of this
Neutrino mass matrices from two zero 3 × 2 Yukawa textures and minimal d = 5 entries
NASA Astrophysics Data System (ADS)
Achelashvili, Avtandil; Tavartkiladze, Zurab
2016-05-01
Aiming to relate leptonic CP violating phase δ to the cosmological CP asymmetry, we study the extension of MSSM by two quasi-degenerate (strictly degenerate at tree level) right-handed neutrinos and consider all possible two texture zero 3 × 2 Yukawa matrices plus one ΔL = 2 dimension five (d = 5) operator contributing to the light neutrino mass matrix. We classify all experimentally viable mass matrices, leading to several predictions, and analytically derive predictive relations. We also relate the CP violating δ phase to the CP phase of the thermal leptogenesis.
Solar neutrino limit on axions and keV-mass bosons
Gondolo, Paolo; Raffelt, Georg G.
2009-05-15
The all-flavor solar neutrino flux measured by the Sudbury Neutrino Observatory constrains nonstandard energy losses to less than about 10% of the Sun's photon luminosity, superseding a helioseismological argument and providing new limits on the interaction strength of low-mass particles. For the axion-photon coupling strength we find g{sub a{gamma}}<7x10{sup -10} GeV{sup -1}. We also derive explicit limits on the Yukawa coupling to electrons of pseudoscalar, scalar, and vector bosons with keV-scale masses.
NASA Astrophysics Data System (ADS)
Melson, Tobias; Janka, Hans-Thomas; Marek, Andreas
2015-03-01
We present the first successful simulation of a neutrino-driven supernova explosion in three dimensions (3D), using the Prometheus-Vertex code with an axis-free Yin-Yang grid and a sophisticated treatment of three-flavor, energy-dependent neutrino transport. The progenitor is a nonrotating, zero-metallicity 9.6 {{M}⊙ } star with an iron core. While in spherical symmetry outward shock acceleration sets in later than 300 ms after bounce, a successful explosion starts at ˜130 ms postbounce in two dimensions (2D). The 3D model explodes at about the same time but with faster shock expansion than in 2D and a more quickly increasing and roughly 10% higher explosion energy of >1050 erg. The more favorable explosion conditions in 3D are explained by lower temperatures and thus reduced neutrino emission in the cooling layer below the gain radius. This moves the gain radius inward and leads to a bigger mass in the gain layer, whose larger recombination energy boosts the explosion energy in 3D. These differences are caused by less coherent, less massive, and less rapid convective downdrafts associated with postshock convection in 3D. The less violent impact of these accretion downflows in the cooling layer produces less shock heating and therefore diminishes energy losses by neutrino emission. We thus have, for the first time, identified a reduced mass accretion rate, lower infall velocities, and a smaller surface filling factor of convective downdrafts as consequences of 3D postshock turbulence that facilitate neutrino-driven explosions and strengthen them compared to the 2D case.
NASA Astrophysics Data System (ADS)
Todd, J.; Chen, R.; Huang, J.; ">MINOS,
A search at Super-Kamiokande for low mass dark matter candidates in the T2K neutrino beam
NASA Astrophysics Data System (ADS)
Nantais, Corina; T2K Collaboration
2015-04-01
The T2K neutrino beam is produced by colliding 30 GeV protons with a graphite target, and some dark sector models predict that a dark matter candidate could be created in the collision. This massive and neutral particle could scatter off a nucleon in Super-Kamiokande, a 50 kilotonne water Cherenkov detector. Similar to the neutral-current quasielastic neutrino-oxygen interaction, the dark matter candidate could interact with the oxygen nucleus, kicking out a nucleon and leaving the nucleus in an excited state. As the nucleus deexcites, 6 MeV gamma-rays are emitted which can be efficiently detected by Super-Kamiokande. The longer time of flight for a dark matter candidate, compared to a neutrino, allows separation between the dark matter induced signal and the neutrino induced background. In the intense global effort to measure dark matter, this complementary search investigates the sub-GeV mass range where other experiments have reduced sensitivity.
Sterile Neutrino Search with MINOS
Devan, Alena V.
2015-08-01
MINOS, Main Injector Neutrino Oscillation Search, is a long-baseline neutrino oscillation experiment in the NuMI muon neutrino beam at the Fermi National Accelerator Laboratory in Batavia, IL. It consists of two detectors, a near detector positioned 1 km from the source of the beam and a far detector 734 km away in Minnesota. MINOS is primarily designed to observe muon neutrino disappearance resulting from three flavor oscillations. The Standard Model of Particle Physics predicts that neutrinos oscillate between three active flavors as they propagate through space. This means that a muon-type neutrino has a certain probability to later interact as a different type of neutrino. In the standard picture, the neutrino oscillation probabilities depend only on three neutrino flavors and two mass splittings, Δm^{2}. An anomaly was observed by the LSND and MiniBooNE experiments that suggests the existence of a fourth, sterile neutrino flavor that does not interact through any of the known Standard Model interactions. Oscillations into a theoretical sterile flavor may be observed by a deficit in neutral current interactions in the MINOS detectors. A distortion in the charged current energy spectrum might also be visible if oscillations into the sterile flavor are driven by a large mass-squared difference, m_{s}^{2} ~ 1 eV^{2}. The results of the 2013 sterile neutrino search are presented here.
Bustamante, Mauricio Winter, Walter; Baerwald, Philipp
2014-11-18
Gamma-ray bursts (GRBs) have long been held as one of the most promising sources of ultra-high energy (UHE) neutrinos. The internal shock model of GRB emission posits the joint production of UHE cosmic rays (UHECRs, above 10{sup 8} GeV), photons, and neutrinos, through photohadronic interactions between source photons and magnetically-confined energetic protons, that occur when relativistically-expanding matter shells loaded with baryons collide with one another. While neutrino observations by IceCube have now ruled out the simplest version of the internal shock model, we show that a revised calculation of the emission, together with the consideration of the full photohadronic cross section and other particle physics effects, results in a prediction of the prompt GRB neutrino flux that still lies one order of magnitude below the current upper bounds, as recently exemplified by the results from ANTARES. In addition, we show that by allowing protons to directly escape their magnetic confinement without interacting at the source, we are able to partially decouple the cosmic ray and prompt neutrino emission, which grants the freedom to fit the UHECR observations while respecting the neutrino upper bounds. Finally, we briefly present advances towards pinning down the precise relation between UHECRs and UHE neutrinos, including the baryonic loading required to fit UHECR observations, and we will assess the role that very large volume neutrino telescopes play in this.
Unification of gauge couplings and the tau-neutrino mass in supergravity without R parity
NASA Astrophysics Data System (ADS)
Díaz, M. A.; Ferrandis, J.; Romão, J. C.; Valle, J. W. F.
2000-12-01
Minimal R-parity violating supergravity predicts a value for αs(M Z) smaller than in the case with conserved R-parity, and therefore closer to the experimental world average. We show that the R-parity violating effect on the αs prediction comes from the larger two-loop b-quark Yukawa contribution to the renormalization group evolution of the gauge couplings which characterizes R-parity violating supergravity. The effect is related to the tau neutrino mass and is sensitive to the initial conditions on the soft supersymmetry breaking parameters at the unification scale. We show how a few percent effect on αs(M Z) may occur even with ντ masses as small as indicated by the simplest neutrino oscillation interpretation of the atmospheric neutrino data from Super-Kamiokande.
NASA Astrophysics Data System (ADS)
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
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 (MH) as a primary physics goal. The excellent energy resolution and the large fiducial volume anticipated for the JUNO detector offer exciting opportunities for addressing many important topics in neutrino and astro-particle physics. In this document, we present the physics motivations and the anticipated performance of the JUNO detector for various proposed measurements. Following an introduction summarizing the current status and open issues in neutrino physics, we discuss how the detection of antineutrinos generated by a cluster of nuclear power plants allows the determination of the neutrino MH at a 3-4σ significance with six years of running of JUNO. The measurement of antineutrino spectrum with excellent energy resolution will also lead to the precise determination of the neutrino oscillation parameters {{sin}}2{θ }12, {{Δ }}{m}212, and | {{Δ }}{m}{ee}2| to an accuracy of better than 1%, which will play a crucial role in the future unitarity test of the MNSP matrix. The JUNO detector is capable of observing not only antineutrinos from the power plants, but also neutrinos/antineutrinos from terrestrial and extra-terrestrial sources, including supernova burst neutrinos, diffuse supernova neutrino background, geoneutrinos, atmospheric neutrinos, and solar neutrinos. As a result of JUNO's large size, excellent energy resolution, and vertex reconstruction capability, interesting new data on these topics can be collected. For example, a neutrino burst from a typical core-collapse supernova at a distance of 10 kpc would lead to ˜5000 inverse-beta-decay events and ˜2000 all-flavor neutrino-proton ES events in JUNO, which are of crucial importance for understanding the mechanism of supernova explosion and for exploring novel phenomena such as collective neutrino oscillations
NASA Astrophysics Data System (ADS)
Arganda, E.; Herrero, M. J.; Marcano, X.; Morales, R.; Szynkman, A.
2017-05-01
In this work we present a new computation of the lepton flavor violating Higgs boson decays that are generated radiatively to one-loop from heavy right-handed neutrinos. We work within the context of the inverse seesaw model with three νR and three extra singlets X , but the results could be generalized to other low scale seesaw models. The novelty of our computation is that it uses a completely different method by means of the mass insertion approximation which works with the electroweak interaction states instead of the usual 9 physical neutrino mass eigenstates of the inverse seesaw model. This method also allows us to write the analytical results explicitly in terms of the most relevant model parameters, that are the neutrino Yukawa coupling matrix Yν and the right-handed mass matrix MR, which is very convenient for a phenomenological analysis. This Yν matrix, being generically nondiagonal in flavor space, is the only one responsible for the induced charged lepton flavor violating processes of our interest. We perform the calculation of the decay amplitude up to order O (Yν2+Yν4). We also study numerically the goodness of the mass insertion approximation results. In the last part we present the computation of the relevant one-loop effective vertex H ℓiℓj for the lepton flavor violating Higgs decay which is derived from a large MR mass expansion of the form factors. We believe that our simple formula found for this effective vertex can be of interest for other researchers who wish to estimate the H →ℓiℓ¯j rates in a fast way in terms of their own preferred input values for the relevant model parameters Yν and MR.
Coloma, Pilar
2016-11-21
Neutrino oscillations have demonstrated that neutrinos have mass and, by now, oscillation experiments have been able to determine most of the parameters in the leptonic mixing matrix with a very good accuracy. Nevertheless, there are still many open questions in the neutrino sector. As a result, I will briefly discuss some of these questions, pointing out possible experimental avenues to address them.
Coloma, Pilar
2016-11-21
Neutrino oscillations have demonstrated that neutrinos have mass and, by now, oscillation experiments have been able to determine most of the parameters in the leptonic mixing matrix with a very good accuracy. Nevertheless, there are still many open questions in the neutrino sector. As a result, I will briefly discuss some of these questions, pointing out possible experimental avenues to address them.
Measuring the mass of a sterile neutrino with a very short baseline reactor experiment
NASA Astrophysics Data System (ADS)
Latimer, D. C.; Escamilla, J.; Ernst, D. J.
2007-04-01
An analysis of the world's neutrino oscillation data, including sterile neutrinos, [M. Sorel, C. M. Conrad, and M. H. Shaevitz, Phys. Rev. D 70, 073004 (2004)] found a peak in the allowed region at a mass-squared difference Δm2≅0.9eV2. We trace its origin to harmonic oscillations in the electron survival probability Pee as a function of L/E, the ratio of baseline to neutrino energy, as measured in the near detector of the Bugey experiment. We find a second occurrence for Δm2≅1.9eV2. We point out that the phenomenon of harmonic oscillations of Pee as a function of L/E, as seen in the Bugey experiment, can be used to measure the mass-squared difference associated with a sterile neutrino in the range from a fraction of an eV2 to several eV2 (compatible with that indicated by the LSND experiment), as well as measure the amount of electron-sterile neutrino mixing. We observe that the experiment is independent, to lowest order, of the size of the reactor and suggest the possibility of a small reactor with a detector sitting at a very short baseline.
Measuring the mass of a sterile neutrino with a very short baseline reactor experiment
Latimer, D. C.; Escamilla, J.; Ernst, D. J.
2007-04-15
An analysis of the world's neutrino oscillation data, including sterile neutrinos, [M. Sorel, C. M. Conrad, and M. H. Shaevitz, Phys. Rev. D 70, 073004 (2004)] found a peak in the allowed region at a mass-squared difference {delta}m{sup 2} congruent with 0.9 eV{sup 2}. We trace its origin to harmonic oscillations in the electron survival probability P{sub ee} as a function of L/E, the ratio of baseline to neutrino energy, as measured in the near detector of the Bugey experiment. We find a second occurrence for {delta}m{sup 2} congruent with 1.9 eV{sup 2}. We point out that the phenomenon of harmonic oscillations of P{sub ee} as a function of L/E, as seen in the Bugey experiment, can be used to measure the mass-squared difference associated with a sterile neutrino in the range from a fraction of an eV{sup 2} to several eV{sup 2} (compatible with that indicated by the LSND experiment), as well as measure the amount of electron-sterile neutrino mixing. We observe that the experiment is independent, to lowest order, of the size of the reactor and suggest the possibility of a small reactor with a detector sitting at a very short baseline.
Neutrino mass hierarchy, vacuum oscillations, and vanishing |U(e3)|
de Gouvea, Andre; Jenkins, James; Kayser, Boris; /Fermilab
2005-03-01
Is the relatively isolated member of the neutrino mass spectrum heavier or lighter than the two closely-spaced members? This question--the character of the neutrino mass hierarchy--is of great theoretical interest. All previously identified experiments for addressing it via neutrino oscillations require that the currently unknown size of the U{sub e3} element of the leptonic mixing matrix (parameterized by the unknown {theta}{sub 13} mixing angle) be sufficiently large, and will utterly fail in the limit {theta}{sub 13} {yields} 0. For this reason, we explore alternative oscillation approaches that would still succeed even if {theta}{sub 13} vanishes. We identify several alternatives that require neither a nonzero |U{sub e3}| nor the presence of significant matter effects. All include multiple percent-level neutrino oscillation measurements, usually involving muon-neutrino (or antineutrino) disappearance and very long baselines. We comment on the degree of promise that these alternative approaches show.
Neutrino mass hierarchy, vacuum oscillations, and vanishing vertical bar U{sub e3} vertical bar
Gouvea, Andre de; Jenkins, James; Kayser, Boris
2005-06-01
Is the relatively isolated member of the neutrino mass spectrum heavier or lighter than the two closely-spaced members? This question--the character of the neutrino mass hierarchy--is of great theoretical interest. All previously identified experiments for addressing it via neutrino oscillations require that the currently unknown size of the U{sub e3} element of the leptonic mixing matrix (parameterized by the unknown {theta}{sub 13} mixing angle) be sufficiently large, and will utterly fail in the limit {theta}{sub 13}{yields}0. For this reason, we explore alternative oscillation approaches that would still succeed even if {theta}{sub 13} vanishes. We identify several alternatives that require neither a nonzero vertical bar U{sub e3} vertical bar nor the presence of significant matter effects (even if the latter are unavoidable in the case of long-baseline, Earth-based experiments). All include multiple percent-level neutrino oscillation measurements, usually involving muon-neutrino (or antineutrino) disappearance and very long baselines. We comment on the degree of promise that these alternative approaches show.
Dasgupta, Basudeb; Dighe, Amol; Mirizzi, Alessandro
2008-10-24
Collective neutrino flavor transformations deep inside a supernova are sensitive to the neutrino mass hierarchy even at extremely small values of theta_(13). Exploiting this effect, we show that comparison of the antineutrino signals from a galactic supernova in two megaton class water Cherenkov detectors, one of which is shadowed by Earth, will enable us to distinguish between the hierarchies if sin(2)theta_(13) < or approximately 10(-5), where long baseline neutrino experiments would be ineffectual.
Overview on Neutrino Theory and Phenomenology
NASA Astrophysics Data System (ADS)
Zhou, Shun
2017-06-01
In this talk, I give an overview on recent theoretical and phenomenological studies of massive neutrinos. First of all, the present status of neutrino mixing parameters is summarized. The phenomenology of neutrino oscillations is then discussed, and current understanding of lepton flavor mixing is presented. Finally, I consider the seesaw models of neutrino masses and briefly mention the direct searches at the CERN Large Hadron Collider (LHC).
Oscillation properties of active and sterile neutrinos and neutrino anomalies at short distances
Khruschov, V. V. Fomichev, S. V. Titov, O. A.
2016-09-15
A generalized phenomenological (3 + 2 + 1) model featuring three active and three sterile neutrinos that is intended for calculating oscillation properties of neutrinos for the case of a normal active neutrino mass hierarchy and a large splitting between the mass of one sterile neutrino and the masses of the other two sterile neutrinos is considered. A new parametrization and a specific form of the general mixing matrix are proposed for active and sterile neutrinos with allowance for possible CP violation in the lepton sector, and test values are chosen for the neutrino masses and mixing parameters. The probabilities for the transitions between different neutrino flavors are calculated, and graphs representing the probabilities for the disappearance of muon neutrinos/antineutrinos and the appearance of electron neutrinos/antineutrinos in a beam of muon neutrinos/antineutrinos versus the distance from the neutrino source for various values of admissible model parameters at neutrino energies not higher than 50 MeV, as well as versus the ratio of this distance to the neutrino energy, are plotted. It is shown that the short-distance accelerator anomaly in neutrino data (LNSD anomaly) can be explained in the case of a specific mixing matrix for active and sterile neutrinos (which belongs to the a{sub 2} type) at the chosen parameter values. The same applies to the short-distance reactor and gallium anomalies. The theoretical results obtained in the present study can be used to interpret and predict the results of ground-based neutrino experiments aimed at searches for sterile neutrinos, as well as to analyze some astrophysical observational data.
Neutrino masses and cosmology with Lyman-alpha forest power spectrum
NASA Astrophysics Data System (ADS)
Palanque-Delabrouille, Nathalie; Yèche, Christophe; Baur, Julien; Magneville, Christophe; Rossi, Graziano; Lesgourgues, Julien; Borde, Arnaud; Burtin, Etienne; LeGoff, Jean-Marc; Rich, James; Viel, Matteo; Weinberg, David
2015-11-01
We present constraints on neutrino masses, the primordial fluctuation spectrum from inflation, and other parameters of the ΛCDM model, using the one-dimensional Lyα-forest power spectrum measured by [1] from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS-III), complemented by Planck 2015 cosmic microwave background (CMB) data and other cosmological probes. This paper improves on the previous analysis by [2] by using a more powerful set of calibrating hydrodynamical simulations that reduces uncertainties associated with resolution and box size, by adopting a more flexible set of nuisance parameters for describing the evolution of the intergalactic medium, by including additional freedom to account for systematic uncertainties, and by using Planck 2015 constraints in place of Planck 2013. Fitting Lyα data alone leads to cosmological parameters in excellent agreement with the values derived independently from CMB data, except for a weak tension on the scalar index ns. Combining BOSS Lyα with Planck CMB constrains the sum of neutrino masses to ∑ mν < 0.12 eV (95% C.L.) including all identified systematic uncertainties, tighter than our previous limit (0.15 eV) and more robust. Adding Lyα data to CMB data reduces the uncertainties on the optical depth to reionization τ, through the correlation of τ with σ8. Similarly, correlations between cosmological parameters help in constraining the tensor-to-scalar ratio of primordial fluctuations r. The tension on ns can be accommodated by allowing for a running dns/d ln k. Allowing running as a free parameter in the fits does not change the limit on ∑ mν. We discuss possible interpretations of these results in the context of slow-roll inflation.
Neutrino masses and cosmology with Lyman-alpha forest power spectrum
Palanque-Delabrouille, Nathalie; Yèche, Christophe; Baur, Julien; Magneville, Christophe; Borde, Arnaud; Burtin, Etienne; LeGoff, Jean-Marc; Rich, James; Lesgourgues, Julien; Viel, Matteo; Weinberg, David E-mail: christophe.yeche@cea.fr E-mail: christophe.magneville@cea.fr E-mail: Julien.Lesgourgues@cern.ch
2015-11-01
We present constraints on neutrino masses, the primordial fluctuation spectrum from inflation, and other parameters of the ΛCDM model, using the one-dimensional Lyα-forest power spectrum measured by [1] from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS-III), complemented by Planck 2015 cosmic microwave background (CMB) data and other cosmological probes. This paper improves on the previous analysis by [2] by using a more powerful set of calibrating hydrodynamical simulations that reduces uncertainties associated with resolution and box size, by adopting a more flexible set of nuisance parameters for describing the evolution of the intergalactic medium, by including additional freedom to account for systematic uncertainties, and by using Planck 2015 constraints in place of Planck 2013. Fitting Lyα data alone leads to cosmological parameters in excellent agreement with the values derived independently from CMB data, except for a weak tension on the scalar index n{sub s}. Combining BOSS Lyα with Planck CMB constrains the sum of neutrino masses to ∑ m{sub ν} < 0.12 eV (95% C.L.) including all identified systematic uncertainties, tighter than our previous limit (0.15 eV) and more robust. Adding Lyα data to CMB data reduces the uncertainties on the optical depth to reionization τ, through the correlation of τ with σ{sub 8}. Similarly, correlations between cosmological parameters help in constraining the tensor-to-scalar ratio of primordial fluctuations r. The tension on n{sub s} can be accommodated by allowing for a running dn{sub s}/d ln k. Allowing running as a free parameter in the fits does not change the limit on ∑ m{sub ν}. We discuss possible interpretations of these results in the context of slow-roll inflation.
What neutrinoless double beta decay would tell us about neutrino mass
Kayser, B. )
1992-02-01
We identify several types of gauge theories, which together comprise a very broad range, in which the observation of neutrinoless double beta decay would imply a significant lower bound on neutrino mass. We explain why these gauge theories have this property.
DESI and other Dark Energy experiments in the era of neutrino mass measurements
Font-Ribera, Andreu; McDonald, Patrick; Mostek, Nick; Reid, Beth A.; Seo, Hee-Jong; Slosar, Anže E-mail: PVMcDonald@lbl.gov E-mail: BAReid@lbl.gov E-mail: anze@bnl.gov
2014-05-01
We present Fisher matrix projections for future cosmological parameter measurements, including neutrino masses, Dark Energy, curvature, modified gravity, the inflationary perturbation spectrum, non-Gaussianity, and dark radiation. We focus on DESI and generally redshift surveys (BOSS, HETDEX, eBOSS, Euclid, and WFIRST), but also include CMB (Planck) and weak gravitational lensing (DES and LSST) constraints. The goal is to present a consistent set of projections, for concrete experiments, which are otherwise scattered throughout many papers and proposals. We include neutrino mass as a free parameter in most projections, as it will inevitably be relevant — DESI and other experiments can measure the sum of neutrino masses to ∼ 0.02 eV or better, while the minimum possible sum is ∼ 0.06 eV. We note that constraints on Dark Energy are significantly degraded by the presence of neutrino mass uncertainty, especially when using galaxy clustering only as a probe of the BAO distance scale (because this introduces additional uncertainty in the background evolution after the CMB epoch). Using broadband galaxy power becomes relatively more powerful, and bigger gains are achieved by combining lensing survey constraints with redshift survey constraints. We do not try to be especially innovative, e.g., with complex treatments of potential systematic errors — these projections are intended as a straightforward baseline for comparison to more detailed analyses.
Forecasts on neutrino mass constraints from the redshift-space two-point correlation function
NASA Astrophysics Data System (ADS)
Petracca, F.; Marulli, F.; Moscardini, L.; Cimatti, A.; Carbone, C.; Angulo, R. E.
2016-11-01
We provide constraints on the accuracy with which the neutrino mass fraction, fν, can be estimated when exploiting measurements of redshift-space distortions, describing in particular how the error on neutrino mass depends on three fundamental parameters of a characteristic galaxy redshift survey: density, halo bias and volume. In doing this, we make use of a series of dark matter halo catalogues extracted from the BASICC simulation. The mock data are analysed via a Markov Chain Monte Carlo likelihood analysis. We find a fitting function that well describes the dependence of the error on bias, density and volume, showing a decrease in the error as the bias and volume increase, and a decrease with density down to an almost constant value for high-density values. This fitting formula allows us to produce forecasts on the precision achievable with future surveys on measurements of the neutrino mass fraction. For example, a Euclid-like spectroscopic survey should be able to measure the neutrino mass fraction with an accuracy of δfν ≈ 3.1 × 10-3 (which is equivalent to δ∑mν ≈ 0.039eV), using redshift-space clustering once all the other cosmological parameters are kept fixed to the ΛCDM case.
Determining the neutrino mass with cyclotron radiation emission spectroscopy—Project 8
NASA Astrophysics Data System (ADS)
Ashtari Esfahani, Ali; Asner, David M.; Böser, Sebastian; Cervantes, Raphael; Claessens, Christine; de Viveiros, Luiz; Doe, Peter J.; Doeleman, Shepard; Fernandes, Justin L.; Fertl, Martin; Finn, Erin C.; Formaggio, Joseph A.; Furse, Daniel; Guigue, Mathieu; Heeger, Karsten M.; Jones, A. Mark; Kazkaz, Kareem; Kofron, Jared A.; Lamb, Callum; LaRoque, Benjamin H.; Machado, Eric; McBride, Elizabeth L.; Miller, Michael L.; Monreal, Benjamin; Mohanmurthy, Prajwal; Nikkel, James A.; Oblath, Noah S.; Pettus, Walter C.; Hamish Robertson, R. G.; Rosenberg, Leslie J.; Rybka, Gray; Rysewyk, Devyn; Saldaña, Luis; Slocum, Penny L.; Sternberg, Matthew G.; Tedeschi, Jonathan R.; Thümmler, Thomas; VanDevender, Brent A.; E Vertatschitsch, Laura; Wachtendonk, Megan; Weintroub, Jonathan; Woods, Natasha L.; Young, André; Zayas, Evan M.
2017-05-01
The most sensitive direct method to establish the absolute neutrino mass is observation of the endpoint of the tritium beta-decay spectrum. Cyclotron radiation emission spectroscopy (CRES) is a precision spectrographic technique that can probe much of the unexplored neutrino mass range with { O }({eV}) resolution. A lower bound of m({ν }e)≳ 9(0.1) {meV} is set by observations of neutrino oscillations, while the KATRIN experiment—the current-generation tritium beta-decay experiment that is based on magnetic adiabatic collimation with an electrostatic (MAC-E) filter—will achieve a sensitivity of m({ν }e)≲ 0.2 {eV}. The CRES technique aims to avoid the difficulties in scaling up a MAC-E filter-based experiment to achieve a lower mass sensitivity. In this paper we review the current status of the CRES technique and describe Project 8, a phased absolute neutrino mass experiment that has the potential to reach sensitivities down to m({ν }e)≲ 40 {meV} using an atomic tritium source.
Neutrino mass^2 inferred from the cosmic ray spectrum and tritium beta decay
NASA Astrophysics Data System (ADS)
Ehrlich, R.
2000-11-01
An earlier prediction of a cosmic ray neutron line right at the energy of the knee of the cosmic ray spectrum was based on the speculation that the electron neutrino is a tachyon whose mass is reciprocally related to the energy of the knee, $E_k$. Given the large uncertainty in $E_k$, the values of ${m_\
Status report on the Livermore-Rockefeller-Fermilab neutrino mass experiment
Fackler, O.; Mugge, M.; Sticker, H.; White, R.M.; Woerner, R.
1986-03-01
An experiment is being performed to determine the electron neutrino mass with the precision of a few eV by measuring the tritium beta decay energy distribution near the endpoint. Key features of the experiment are a 2 eV resolution electrostatic spectrometer and a high-activity frozen tritium source.
DESI and other Dark Energy experiments in the era of neutrino mass measurements
Font-Ribera, Andreu; McDonald, Patrick; Mostek, Nick; Reid, Beth A.; Seo, Hee-Jong; Slosar, Anže
2014-05-19
Here we present Fisher matrix projections for future cosmological parameter measurements, including neutrino masses, Dark Energy, curvature, modified gravity, the inflationary perturbation spectrum, non-Gaussianity, and dark radiation. We focus on DESI and generally redshift surveys (BOSS, HETDEX, eBOSS, Euclid, and WFIRST), but also include CMB (Planck) and weak gravitational lensing (DES and LSST) constraints. The goal is to present a consistent set of projections, for concrete experiments, which are otherwise scattered throughout many papers and proposals. We include neutrino mass as a free parameter in most projections, as it will inevitably be relevant $-$ DESI and other experiments can measure the sum of neutrino masses to ~ 0.02 eV or better, while the minimum possible sum is 0.06 eV. We note that constraints on Dark Energy are significantly degraded by the presence of neutrino mass uncertainty, especially when using galaxy clustering only as a probe of the BAO distance scale (because this introduces additional uncertainty in the background evolution after the CMB epoch). Using broadband galaxy power becomes relatively more powerful, and bigger gains are achieved by combining lensing survey constraints with redshift survey constraints. Finally, we do not try to be especially innovative, e.g., with complex treatments of potential systematic errors $-$ these projections are intended as a straightforward baseline for comparison to more detailed analyses.
DESI and other Dark Energy experiments in the era of neutrino mass measurements
Font-Ribera, Andreu; McDonald, Patrick; Mostek, Nick; ...
2014-05-19
Here we present Fisher matrix projections for future cosmological parameter measurements, including neutrino masses, Dark Energy, curvature, modified gravity, the inflationary perturbation spectrum, non-Gaussianity, and dark radiation. We focus on DESI and generally redshift surveys (BOSS, HETDEX, eBOSS, Euclid, and WFIRST), but also include CMB (Planck) and weak gravitational lensing (DES and LSST) constraints. The goal is to present a consistent set of projections, for concrete experiments, which are otherwise scattered throughout many papers and proposals. We include neutrino mass as a free parameter in most projections, as it will inevitably be relevant $-$ DESI and other experiments can measuremore » the sum of neutrino masses to ~ 0.02 eV or better, while the minimum possible sum is 0.06 eV. We note that constraints on Dark Energy are significantly degraded by the presence of neutrino mass uncertainty, especially when using galaxy clustering only as a probe of the BAO distance scale (because this introduces additional uncertainty in the background evolution after the CMB epoch). Using broadband galaxy power becomes relatively more powerful, and bigger gains are achieved by combining lensing survey constraints with redshift survey constraints. Finally, we do not try to be especially innovative, e.g., with complex treatments of potential systematic errors $-$ these projections are intended as a straightforward baseline for comparison to more detailed analyses.« less
Experimental data on solar neutrinos
NASA Astrophysics Data System (ADS)
Ludhova, Livia
2016-04-01
Neutrino physics continues to be a very active research field, full of opened fundamental questions reaching even beyond the Standard Model of elementary particles and towards a possible new physics. Solar neutrinos have played a fundamental historical role in the discovery of the phenomenon of neutrino oscillations and thus non-zero neutrino mass. Even today, the study of solar neutrinos provides an important insight both into the neutrino as well as into the stellar and solar physics. In this section we give an overview of the most important solar-neutrino measurements from the historical ones up to the most recent ones. We cover the results from the experiments using radio-chemic (Homestake, SAGE, GNO, GALLEX), water Cherenkov (Kamiokande, Super-Kamiokande, SNO), and the liquid-scintillator (Borexino, KamLAND) detection techniques.
Saito, Shun; Takada, Masahiro; Taruya, Atsushi
2011-02-15
We compare the model power spectrum, computed based on perturbation theory, with the power spectrum of luminous red galaxies (LRG) measured from the Sloan Digital Sky Survey Data Release 7 catalog, assuming a flat, cold dark matter-dominated cosmology. The model includes the effects of massive neutrinos, nonlinear matter clustering and nonlinear, scale-dependent galaxy bias in a self-consistent manner. We first test the accuracy of the perturbation theory model by comparing the model predictions with the halo power spectrum in real- and redshift-space, measured from 70 simulation realizations for a cold dark matter model without massive neutrinos. We show that the perturbation theory model with bias parameters being properly adjusted can fairly well reproduce the simulation results. As a result, the best-fit parameters obtained from the hypothetical parameter fitting recover, within statistical uncertainties, the input cosmological parameters in simulations, including an upper bound on neutrino mass, if the power spectrum information up to k{approx_equal}0.15 hMpc{sup -1} is used. However, for the redshift-space power spectrum, the best-fit cosmological parameters show a sizable bias from the input values if using the information up to k{approx_equal}0.2 hMpc{sup -1}, probably due to nonlinear redshift distortion effect. Given these tests, we decided, as a conservative choice, to use the LRG power spectrum up to k=0.1 hMpc{sup -1} in order to minimize possible unknown nonlinearity effects. In combination with the recent results from Wilkinson Microwave Background Anisotropy Probe (WMAP), we derive a robust upper bound on the sum of neutrino masses, given as (95% C.L.), marginalized over other parameters including nonlinear bias parameters and dark energy equation of state parameter. The upper bound is only slightly improved to if including the LRG spectrum up to k=0.2 hMpc{sup -1}, due to severe parameter degeneracies, although the constraint may be biased as
A model for neutrino emission from nuclear accretion disks
NASA Astrophysics Data System (ADS)
Deaton, Michael
2015-04-01
Compact object mergers involving at least one neutron star can produce short-lived black hole accretion engines. Over tens to hundreds of milliseconds such an engine consumes a disk of hot, nuclear-density fluid, and drives changes to its surrounding environment through luminous emission of neutrinos. The neutrino emission may drive an ultrarelativistic jet, may peel off the disk's outer layers as a wind, may irradiate those winds or other forms of ejecta and thereby change their composition, may change the composition and thermodynamic state of the disk itself, and may oscillate in its flavor content. We present the full spatial-, angular-, and energy-dependence of the neutrino distribution function around a realistic model of a nuclear accretion disk, to inform future explorations of these types of behaviors. Spectral Einstein Code (SpEC).
Matter-Induced Neutrino Oscillation in Double Universal Seesaw Model
NASA Astrophysics Data System (ADS)
Sogami, I. S.; Shinohara, T.; Egawa, Y.
1992-04-01
The Mikheyev-Smirnov-Wolfenstein effect is investigated in an extended gauge field theory in which the universal seesaw mechanism is applied singly to the charged fermion sectors to lower their masses below the electroweak energy scale and doubly to the neutral fermion sector to make neutrinos superlight. At the first seesaw approximation, neutrinos are proved to have a distinctive spectrum consisting of doubly degenerate states with smaller mass m_{S} and a singlet state with larger mas m_{L}. The lepton mixing matrix is determined definitely in terms of the masses of charged leptons and down quarks, with a very small vacuum mixing angle sin theta = 0.043 +/- 0.004. The Schrödinger-like equation describing the spatial evolution of stationary neutrino flux is solved for globally-rotated-flavor wave functions. Comparison of its nonadiabatic solution with experimental results leads to an estimation m_{L}(2) - m_{S}(2) = (6 +/- 2) x 10(-6) eV(2) for the squared mass difference and a capture rate prediction of 74 +/- 12 SNU for the SAGE gallium experiment.
Effect of the charged-lepton's mass on the quasielastic neutrino cross sections
NASA Astrophysics Data System (ADS)
Ankowski, Artur M.
2017-09-01
Martini et al. [Phys. Rev. C 94, 015501 (2016), 10.1103/PhysRevC.94.015501] recently observed that when the produced-lepton's mass plays an important role, the charged-current quasielastic cross section for muon neutrinos can be higher than that for electron neutrinos. Here I argue that this effect appears solely in the theoretical descriptions of nuclear effects in which nucleon knockout requires the energy and momentum transfers to lie in a narrow range of the kinematically allowed values.
Thermal vacuum, cosmic microwave radiation, neutrino masses and fractal-like self-similar structure
NASA Astrophysics Data System (ADS)
Capolupo, Antonio; Lambiase, Gaetano; Vitiello, Giuseppe
2017-08-01
The behavior of thermal vacuum condensates of scalar and fermion fields is analyzed and it is shown that the condensate of Maxwell fields reproduces the characteristics of the cosmic microwave radiation. By studying fermion thermal states with the temperature of the cosmic neutrino background, we derive a value of the sum of the active neutrino masses which is compatible with its estimated lower bound. Moreover, we reveal the fractal self-similar structure of the thermal radiation and we relate it to the coherent structure of the thermal vacuum.
X. Qian, D. A. Dwyer, R. D. McKeown, P. Vogel, W. Wang, C. Zhang`
2013-02-01
Determination of the neutrino mass hierarchy using a reactor neutrino experiment at ∼60 km is analyzed. Such a measurement is challenging due to the finite detector resolution, the absolute energy scale calibration, and the degeneracies caused by current experimental uncertainty of |Δm{sub 32}{sup 2}|. The standard {chi}{sup 2} method is compared with a proposed Fourier transformation method. In addition, we show that for such a measurement to succeed, one must understand the nonlinearity of the detector energy scale at the level of a few tenths of percent.
Audren, Benjamin; Lesgourgues, Julien; Bird, Simeon; Haehnelt, Martin G.; Viel, Matteo E-mail: julien.lesgourgues@cern.ch E-mail: haehnelt@ast.cam.ac.uk
2013-01-01
We present forecasts for the accuracy of determining the parameters of a minimal cosmological model and the total neutrino mass based on combined mock data for a future Euclid-like galaxy survey and Planck. We consider two different galaxy surveys: a spectroscopic redshift survey and a cosmic shear survey. We make use of the Monte Carlo Markov Chains (MCMC) technique and assume two sets of theoretical errors. The first error is meant to account for uncertainties in the modelling of the effect of neutrinos on the non-linear galaxy power spectrum and we assume this error to be fully correlated in Fourier space. The second error is meant to parametrize the overall residual uncertainties in modelling the non-linear galaxy power spectrum at small scales, and is conservatively assumed to be uncorrelated and to increase with the ratio of a given scale to the scale of non-linearity. It hence increases with wavenumber and decreases with redshift. With these two assumptions for the errors and assuming further conservatively that the uncorrelated error rises above 2% at k = 0.4 h/Mpc and z = 0.5, we find that a future Euclid-like cosmic shear/galaxy survey achieves a 1-σ error on M{sub ν} close to 32 meV/25 meV, sufficient for detecting the total neutrino mass with good significance. If the residual uncorrelated errors indeed rises rapidly towards smaller scales in the non-linear regime as we have assumed here then the data on non-linear scales does not increase the sensitivity to the total neutrino mass. Assuming instead a ten times smaller theoretical error with the same scale dependence, the error on the total neutrino mass decreases moderately from σ(M{sub ν}) = 18 meV to 14 meV when mildly non-linear scales with 0.1 h/Mpc < k < 0.6 h/Mpc are included in the analysis of the galaxy survey data.
Phenomenology of pseudo Dirac neutrinos
NASA Astrophysics Data System (ADS)
Joshipura, A. S.; Rindani, S. D.
2000-11-01
We formulate general conditions on /3×3 neutrino mass matrices under which a degenerate pair of neutrinos at a high scale would split at low scale by radiative corrections involving only the standard model fields. This generalizes the original observations of Wolfenstein on pseudo Dirac neutrinos to three generations. A specific model involving partially broken discrete symmetry and solving the solar and atmospheric anomalies is proposed. The symmetry pattern of the model naturally generates two large angles one of which can account for the large angle MSW solution to the solar neutrino problem.
The Absolute Mass of Neutrino and the First Unique Forbidden β-DECAY of 187Re
NASA Astrophysics Data System (ADS)
Dvornický, Rastislav; Šimkovic, Fedor; Muto, Kazuo
2011-10-01
The planned rhenium β-decay experiment MARE might probe the absolute mass scale of neutrinos with the same sensitivity as the tritium β-decay experiment KATRIN, which will start data taking in 2011 and will proceed for five years. We present the energy distribution of emitted electrons for the first unique forbidden β-decay of 187Re. It is found that the p-wave emission of electron dominates over the s-wave. By assuming mixing of three neutrinos the Kurie function for the rhenium β-decay is derived. It is shown that the Kurie plot near the endpoint is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed βof 3H.
Neutrino and gravitational wave signal of a delayed-detonation model of type Ia supernovae
NASA Astrophysics Data System (ADS)
Seitenzahl, Ivo R.; Herzog, Matthias; Ruiter, Ashley J.; Marquardt, Kai; Ohlmann, Sebastian T.; Röpke, Friedrich K.
2015-12-01
The progenitor system(s) and the explosion mechanism(s) of type Ia supernovae (SNe Ia) are still under debate. Nonelectromagnetic observables, in particular, gravitational waves and neutrino emission, of thermoclear supernovae are a complementary window to light curves and spectra for studying these enigmatic objects. A leading model for SNe Ia is the thermonuclear incineration of a near-Chandrasekhar mass carbon-oxygen white dwarf star in a "delayed detonation." We calculate a three-dimensional hydrodynamic explosion for the N100 delayed-detonation model extensively discussed in the literature, taking the dynamical effects of neutrino emission from all important contributing source terms into account. Although neutrinos carry away 2 ×1049 erg of energy, we confirm the common view that neutrino energy losses are dynamically not very important, resulting in only a modest reduction of final kinetic energy by 2%. We then calculate the gravitational wave signal from the time evolution of the quadrupole moment. Our model radiates 7 ×1039 erg in gravitational waves and the spectrum has a pronounced peak around 0.4 Hz. Depending on viewing angle and polarization, we find that the future space-based gravitational wave missions DECIGO and BBO would be able to detect our source to a distance of ˜1.3 Mpc . We predict a clear signature of the deflagration-to-detonation transition in the neutrino and the gravitational wave signals. If observed, such a feature would be a strong indicator of the realization of delayed detonations in near-Chandrasekhar mass white dwarfs.
The analysis of solar models: Neutrinos and oscillations
NASA Technical Reports Server (NTRS)
Ulrich, R. K.; Rhodes, E. J., Jr.; Tomczyk, S.; Dumont, P. J.; Brunish, W. M.
1983-01-01
Tests of solar neutrino flux and solar oscillation frequencies were used to assess standard stellar structure theory. Standard and non-standard solar models are enumerated and discussed. The field of solar seismology, wherein the solar interior is studied from the measurement of solar oscillations, is introduced.
CP violation from the neutrino sector: A case for the superweak model
Holdom, B.
1998-01-01
We discuss how CP violation originating in the right-handed neutrino sector can feed into the quark sector in an otherwise CP invariant theory. The dominant effects are superweak, and we suggest that this may yield a natural resolution of the strong CP problem. This work builds on and extends a previously proposed model of quark and lepton masses, based on a new strong flavor interaction above the weak scale. {copyright} {ital 1997} {ital The American Physical Society}
Light sterile neutrinos from large extra dimensions
NASA Astrophysics Data System (ADS)
Ma, E.; Rajasekaran, G.; Sarkar, U.
2000-12-01
An experimentally verifiable Higgs-triplet model of neutrino masses from large extra dimensions was recently proposed. We extend it to accommodate a light sterile neutrino which also mixes with the three active neutrinos. Another extension without the Higgs triplet allows the specific realization of a previously proposed phenomenological model of neutrino oscillations with decay to account for the LSND data, which is now the only viable such model now left, in view of the latest atmospheric and solar neutrino-oscillation data from the Super-Kamiokande collaboration.
Right-handed neutrino dark matter in left-right symmetric models
NASA Astrophysics Data System (ADS)
Bhupal Dev, P. S.; Mohapatra, Rabindra N.; Zhang, Yongchao
2017-07-01
We show that in a class of non-supersymmetric left-right extensions of the Standard Model (SM), the lightest right-handed neutrino (RHN) is naturally stable and can therefore play the role of thermal Dark Matter (DM) in the Universe for a wide mass range from TeV to PeV. Our model is based on the gauge group SU(3) c × SU(2) L × SU(2) R × U(1) YL × U(1) YR in which a heavy copy of the SM fermions are introduced and the stability of the RHN DM is guaranteed by an automatic Z 2 symmetry present in the leptonic sector. The active neutrino masses in the model arise from the type-II seesaw mechanism. We find a lower bound on the RHN DM mass of order TeV from relic density constraints, as well as an unitarity upper bound in the multi-TeV to PeV scale, depending on the entropy dilution factor. The RHN DM could be made long-lived by soft-breaking of the Z 2 symmetry and provides a concrete example of decaying DM interpretation of the PeV neutrinos observed at IceCube.
Heavy right-handed neutrino dark matter in left-right models
NASA Astrophysics Data System (ADS)
Dev, P. S. Bhupal; Mohapatra, Rabindra N.; Zhang, Yongchao
2017-05-01
We show that in a class of non-supersymmetric left-right extensions of the Standard Model (SM), the lightest right-handed neutrino (RHN) can play the role of thermal Dark Matter (DM) in the Universe for a wide mass range from TeV to PeV. Our model is based on the gauge group SU(3)c ×SU(2)L ×SU(2)R ×U(1)YL ×U(1)YR in which a heavy copy of the SM fermions is introduced and the stability of the RHN DM is guaranteed by an automatic Z2 symmetry present in the leptonic sector. In such models, the active neutrino masses are obtained via the type-II seesaw mechanism. We find a lower bound on the RHN DM mass of order TeV from relic density constraints, as well as a unitarity upper bound in the multi-TeV to PeV scale, depending on the entropy dilution factor. The RHN DM could be made long-lived by soft-breaking of the Z2 symmetry and provides a concrete example of decaying DM interpretation of the PeV neutrinos observed at IceCube.
NASA Astrophysics Data System (ADS)
Roncarelli, M.; Villaescusa-Navarro, F.; Baldi, M.
2017-01-01
The study of neutrinos in astrophysics requires the combination of different observational probes. The temperature anisotropies of the cosmic microwave background induced via the kinematic Sunyaev-Zel'dovich (kSZ) effect may provide interesting information since they are expected to receive significant contribution from high-redshift plasma. We present a set of cosmological hydrodynamical simulations that include a treatment of the neutrino component considering 4 different sum of neutrino masses: Σmν = (0, 0.15, 0.3, 0.6) eV. Using their outputs we modelled the kSZ effect due to the large-scale structure after the reionisation by producing mock maps, then computed the kSZ power spectrum and studied how it depends on zre and Σmν. We also run as set of 4 simulations to study and correct possible systematics due to resolution, finite box size and astrophysics. With massless neutrinos we obtain D^kSZ_{3000}=4.0 μK2 (zre=8.8), enough to account for all of the kSZ signal of D^kSZ_{3000}=(2.9 ± 1.3)μK2 measured with the South Pole Telescope (George et al. 2015). This translates into an upper limit on the kSZ effect due to patchy reionisation of D^kSZ,patchy_{3000}<1.0 μK2 (95% C.L.). Massive neutrinos induce a damping of kSZ effect power of about 8, 12 and 40 per cent for Σmν = (0.15, 0.3, 0.6) eV, respectively. We study the dependence of the kSZ signal with zre and the neutrino mass fraction, fν, and obtain D^kSZ_{3000}∝zre0.26(1 - fν)14.3. Interestingly, the scaling with fν is significantly shallower with respect to the equivalent thermal SZ effect, and may be used to break the degeneracy with other cosmological parameters.
Supernova bound on keV-mass sterile neutrinos reexamined
Raffelt, Georg G.; Zhou Shun
2011-05-01
Active-sterile neutrino mixing is strongly constrained for m{sub s} < or approx. 100 keV to avoid excessive energy losses from supernova cores. For smaller m{sub s}, matter effects suppress the effective mixing angle except for a resonant range of energies where it is enhanced. We study the case of {nu}{sub {tau}-{nu}s} mixing where a {nu}{sub {tau}-{nu}{tau}} asymmetry builds up due to the strong excess of {nu}{sub s} over {nu}{sub s} emission or vice versa, reducing the overall emission rate. In the warm dark matter range m{sub s} < or approx. 10 keV the mixing angle is essentially unconstrained.
Gravitationally confined relativistic neutrinos
NASA Astrophysics Data System (ADS)
Vayenas, C. G.; Fokas, A. S.; Grigoriou, D.
2017-09-01
Combining special relativity, the equivalence principle, and Newton’s universal gravitational law with gravitational rather than rest masses, one finds that gravitational interactions between relativistic neutrinos with kinetic energies above 50 MeV are very strong and can lead to the formation of gravitationally confined composite structures with the mass and other properties of hadrons. One may model such structures by considering three neutrinos moving symmetrically on a circular orbit under the influence of their gravitational attraction, and by assuming quantization of their angular momentum, as in the Bohr model of the H atom. The model contains no adjustable parameters and its solution, using a neutrino rest mass of 0.05 eV/c2, leads to composite state radii close to 1 fm and composite state masses close to 1 GeV/c2. Similar models of relativistic rotating electron - neutrino pairs give a mass of 81 GeV/c2, close to that of W bosons. This novel mechanism of generating mass suggests that the Higgs mass generation mechanism can be modeled as a latent gravitational field which gets activated by relativistic neutrinos.
SN1987A-Neutrino emission from Supernova': in Dynamic universe model of cosmology
NASA Astrophysics Data System (ADS)
Naga Parameswara Gupta, Satyavarapu
SN1987A-Neutrino emission from supernova before the star bursts' is an important discovery, when viewed from `Dynamic universe model of cosmology' point of view. In OMEG05, we have successfully presented the reasons for calculation error called `missing mass' in an inhomoge-neous, anisotropic and multi-body Dynamic universe Model, where this error is not occurring. But there are some new voices that say about generation of some flavors of neutrinos during Bigbang. We find from SN1987A Neutrino generation covers all flavors. Remaining flavors of Neutrinos are generated from sun and stars. This covers the whole spectrum. This paper covers all these aspects. And other earlier results by Dynamic Universe Model 1. Offers Singularity free solutions 2. Non-collapsing Galaxy structures 3. Solving Missing mass in Galaxies, and it finds reason for Galaxy circular velocity curves. . . . 4. Blue shifted and red shifted Galaxies co-existence. . . 5. Explains the force behind expansion of universe. 6. Explains the large voids and non-uniform matter densities. 7. Explains the Pioneer anomaly 8. Predicts the trajectory of New Horizons satellite. 9 Jeans swindle test 10. Existence of large number of blue shifted Galaxies `SITA Simulations' software was developed about 18 years back for Dynamic Universe Model of Cosmology. It is based on Newtonian physics. It is Classical singularity free N-body tensor solution to the old problem announced by King Oscar II and tried by Poincare in year AD1888 for 133 masses, tested extensively for so many years. This was developed on 486 based PC of those days; the same software was used repeatedly for so many years for solving different Physical problems on Different PCs and Laptops. It is based on Dynamic Universe Model's mathematical back ground.
Precision Studies at the Neutrino Frontier
NASA Astrophysics Data System (ADS)
Heeger, Karsten M.
2013-04-01
Neutrinos were proposed as a remedy to explain nuclear beta decay and are now essential in our understanding of the Universe. Neutrinos determine the abundance of light elements, are critical to supernova explosions, and may hold the key to understanding the matter-antimatter asymmetry. Studies of neutrinos from the Sun and nuclear reactors have confirmed the prediction of solar models and provided evidence for neutrino flavor oscillation. The observation of neutrino oscillation is amongst the major discoveries and demands that we make the first significant revision of the Standard Model. The search for neutrinoless double beta decay is the only experimental approach to probing the Majorana nature of neutrinos and will provide insight into the fundamental nature of neutrino mass. I will review Stuart Freedman's contributions to neutrino physics and in advancing the field to precision measurements.
Low mass binary neutron star mergers: Gravitational waves and neutrino emission
NASA Astrophysics Data System (ADS)
Foucart, Francois; Haas, Roland; Duez, Matthew D.; O'Connor, Evan; Ott, Christian D.; Roberts, Luke; Kidder, Lawrence E.; Lippuner, Jonas; Pfeiffer, Harald P.; Scheel, Mark A.
2016-02-01
Neutron star mergers are among the most promising sources of gravitational waves for advanced ground-based detectors. These mergers are also expected to power bright electromagnetic signals, in the form of short gamma-ray bursts, infrared/optical transients powered by r-process nucleosynthesis in neutron-rich material ejected by the merger, and radio emission from the interaction of that ejecta with the interstellar medium. Simulations of these mergers with fully general relativistic codes are critical to understand the merger and postmerger gravitational wave signals and their neutrinos and electromagnetic counterparts. In this paper, we employ the Spectral Einstein Code to simulate the merger of low mass neutron star binaries (two 1.2 M⊙ neutron stars) for a set of three nuclear-theory-based, finite temperature equations of state. We show that the frequency peaks of the postmerger gravitational wave signal are in good agreement with predictions obtained from recent simulations using a simpler treatment of gravity. We find, however, that only the fundamental mode of the remnant is excited for long periods of time: emission at the secondary peaks is damped on a millisecond time scale in the simulated binaries. For such low mass systems, the remnant is a massive neutron star which, depending on the equation of state, is either permanently stable or long lived (i.e. rapid uniform rotation is sufficient to prevent its collapse). We observe strong excitations of l =2 , m =2 modes, both in the massive neutron star and in the form of hot, shocked tidal arms in the surrounding accretion torus. We estimate the neutrino emission of the remnant using a neutrino leakage scheme and, in one case, compare these results with a gray two-moment neutrino transport scheme. We confirm the complex geometry of the neutrino emission, also observed in previous simulations with neutrino leakage, and show explicitly the presence of important differences in the neutrino luminosity, disk
Neutrino oscillations in a model with a source and detector
Kiers, K.; Weiss, N. ||
1998-03-01
We study the oscillations of neutrinos in a model in which the neutrino is coupled to a localized, idealized source and detector. By varying the spatial and temporal resolution of the source and detector we are able to model the full range of source and detector types ranging from coherent to incoherent. We find that this approach is useful in understanding the interface between the quantum mechanical nature of neutrino oscillations on the one hand and the production and detection systems on the other hand. This method can easily be extended to study the oscillations of other particles such as the neutral K and B mesons. We find that this approach gives a reliable way to treat the various ambiguities which arise when one examines the oscillations from a wave packet point of view. We demonstrate that the conventional oscillation formula is correct in the relativistic limit and that several recent claims of an extra factor of 2 in the oscillation length are incorrect. We also demonstrate {ital explicitly} that the oscillations of neutrinos which have separated spatially may be {open_quotes}revived{close_quotes} by a long coherent measurement. {copyright} {ital 1998} {ital The American Physical Society}
Majorana Neutrino Masses by Spectroscopic Studies of Double Beta Decays and Moon
NASA Astrophysics Data System (ADS)
Ejiri, Hiroyasu
This is a brief review of spectroscopic studies of neutrino-less double beta decays (0νββ) and the MOON (Mo Observatory Of Neutrinos) project. It aims at studying the Majorana nature of neutrinos and the mass spectrum by spectroscopic studies of 0νββ with ν-mass sensitivity of
Resolving the mass hierarchy with atmospheric neutrinos using a liquid argon detector
Gandhi, Raj; Ghoshal, Pomita; Goswami, Srubabati; Sankar, S. Uma
2008-10-01
We explore the potential offered by large-mass liquid argon detectors for determination of the sign of {delta}m{sub 31}{sup 2}, or the neutrino mass hierarchy, through interactions of atmospheric neutrinos. We give results for a 100 kT sized magnetized detector which provides separate sensitivity to {nu}{sub {mu}}, {nu}{sub {mu}} and, over a limited energy range, to {nu}{sub e}, {nu}{sub e}. We also discuss the sensitivity for the unmagnetized version of such a detector. After including the effect of smearing in neutrino energy and direction and incorporating the relevant statistical, theoretical, and systematic errors, we perform a binned {chi}{sup 2} analysis of simulated data. The {chi}{sup 2} is marginalized over the presently allowed ranges of neutrino parameters and determined as a function of {theta}{sub 13}. We find that such a detector offers superior capabilities for hierarchy resolution, allowing a >4{sigma} determination for a 100 kT detector over a 10-year running period for values of sin{sup 2}2{theta}{sub 13}{>=}0.05. For an unmagnetized detector, a 2.5{sigma} hierarchy sensitivity is possible for sin{sup 2}2{theta}{sub 13}=0.04.
Constraints from primordial nucleosynthesis on the mass of the tau neutrino
NASA Technical Reports Server (NTRS)
Kolb, Edward W.; Turner, Michael S.; Chakravorty, A.; Schramm, David N.
1991-01-01
It is shown that primordial nucleosynthesis excludes a tau-neutrino mass from 0.3 to 25 MeV (Dirac) and 0.5 to 25 MeV (Majorana) provided that its lifetime is not less than about 1 sec, and from 0.3 to 30 MeV (Dirac) and 0.5 to 32 MeV (Majorana) for a lifetime of not less than about 1000 sec. A modest improvement in the laboratory mass limit - from 35 to 25 MeV - would imply that the tau-neutrino mass must be less than 0.5 MeV (provided the lifetime is not less than about 1 sec).
Constraints from primordial nucleosynthesis on the mass of the tau neutrino
NASA Technical Reports Server (NTRS)
Kolb, Edward W.; Turner, Michael S.; Chakravorty, A.; Schramm, David N.
1991-01-01
It is shown that primordial nucleosynthesis excludes a tau-neutrino mass from 0.3 to 25 MeV (Dirac) and 0.5 to 25 MeV (Majorana) provided that its lifetime is not less than about 1 sec, and from 0.3 to 30 MeV (Dirac) and 0.5 to 32 MeV (Majorana) for a lifetime of not less than about 1000 sec. A modest improvement in the laboratory mass limit - from 35 to 25 MeV - would imply that the tau-neutrino mass must be less than 0.5 MeV (provided the lifetime is not less than about 1 sec).
A neutrino model fit to the CMB power spectrum
NASA Astrophysics Data System (ADS)
Shanks, T.; Johnson, R. W. F.; Schewtschenko, J. A.; Whitbourn, J. R.
2014-12-01
The standard cosmological model, Λ cold dark matter (ΛCDM), provides an excellent fit to cosmic microwave background (CMB) data. However, the model has well-known problems. For example, the cosmological constant, Λ, is fine-tuned to 1 part in 10100 and the CDM particle is not yet detected in the laboratory. Shanks previously investigated a model which assumed neither exotic particles nor a cosmological constant but instead postulated a low Hubble constant (H0) to allow a baryon density compatible with inflation and zero spatial curvature. However, recent Planck results make it more difficult to reconcile such a model with CMB power spectra. Here, we relax the previous assumptions to assess the effects of assuming three active neutrinos of mass ≈5 eV. If we assume a low H0 ≈ 45 km s-1 Mpc-1 then, compared to the previous purely baryonic model, we find a significantly improved fit to the first three peaks of the Planck power spectrum. Nevertheless, the goodness of fit is still significantly worse than for ΛCDM and would require appeal to unknown systematic effects for the fit ever to be considered acceptable. A further serious problem is that the amplitude of fluctuations is low (σ8 ≈ 0.2), making it difficult to form galaxies by the present day. This might then require seeds, perhaps from a primordial magnetic field, to be invoked for galaxy formation. These and other problems demonstrate the difficulties faced by models other than ΛCDM in fitting ever more precise cosmological data.
Renormalisation group analysis of single right-handed neutrino dominance
NASA Astrophysics Data System (ADS)
King, S. F.; Nimai Singh, N.
2000-12-01
We perform a renormalisation group (RG) analysis of neutrino masses and mixing angles in the see-saw mechanism in the minimal supersymmetric standard model with three right-handed neutrinos, including the effects of the heavy neutrino thresholds. We focus on the case that one of the right-handed neutrinos provides the dominant contribution to the 23 block of the light Majorana matrix, causing its determinant to approximately vanish and giving an automatic neutrino mass hierarchy, so-called single right-handed neutrino dominance which may arise from a U(1) family symmetry. In these models radiative corrections can increase atomospheric and solar neutrino mixing by up to about 10% and 5%, respectively, and may help to achieve bi-maximal mixing. Significantly we find that the radiative corrections over the heavy neutrino threshold region are at least as important as those usually considered from the lightest right-handed neutrino down to low energies.
Freeze-in production of sterile neutrino dark matter in U(1){sub B−L} model
Biswas, Anirban; Gupta, Aritra
2016-09-27
With the advent of new and more sensitive direct detection experiments, scope for a thermal WIMP explanation of dark matter (DM) has become extremely constricted. The non-observation of thermal WIMP in these experiments has put a strong upper bound on WIMP-nucleon scattering cross section and within a few years it is likely to overlap with the coherent neutrino-nucleon cross section. Hence in all probability, DM may have some non-thermal origin. In this work we explore in detail this possibility of a non-thermal sterile neutrino DM within the framework of U(1){sub B−L} model. The U(1){sub B−L} model on the other hand is a well-motivated and minimal way of extending the standard model so that it can explain the neutrino masses via Type-I see-saw mechanism. We have shown, besides explaining the neutrino mass, it can also accommodate a non-thermal sterile neutrino DM with correct relic density. In contrast with the existing literature, we have found that W{sup ±} decay can also be a dominant production mode of the sterile neutrino DM. To obtain the comoving number density of dark matter, we have solved here a coupled set of Boltzmann equations considering all possible decay as well as annihilation production modes of the sterile neutrino dark matter. The framework developed here though has been done for a U(1){sub B−L} model, can be applied quite generally for any models with an extra neutral gauge boson and a fermionic non-thermal dark matter.