Mass and oscillations of Dirac neutrinos
International Nuclear Information System (INIS)
Collot, J.
1989-01-01
In the most economical extension of the standard model, we have presented the theory of massive Dirac neutrinos. We have particularly emphasized that, in this model, a complete analogy between quarks and leptons can be erected and predicts neutrino flavor oscillations. We have reviewed the last experimental results concerning kinetic neutrino mass experiments and neutrino oscillation investigations
Majorana mass term, Dirac neutrinos and selective neutrino oscillations
International Nuclear Information System (INIS)
Leung, C.N.
1987-01-01
In a theory of neutrino mixing via a Majorana mass term involving only the left-handed neutrinos there exist selection rules for neutrino oscillations if true Dirac and/or exactly zero mass eigenstates are present. In the case of three neutrino flavours no oscillation is allowed if the mass spectrum contains one Dirac and one nondegenerate Majorana massive neutrino. The origin of these selection rules and their implications are discussed and the number of possible CP-violating phases in the lepton mixing matrix when Dirac and Majorana mass eigenstates coexist is given. (orig.)
Renormalization group evolution of Dirac neutrino masses
International Nuclear Information System (INIS)
Lindner, Manfred; Ratz, Michael; Schmidt, Michael Andreas
2005-01-01
There are good reasons why neutrinos could be Majorana particles, but there exist also a number of very good reasons why neutrinos could have Dirac masses. The latter option deserves more attention and we derive therefore analytic expressions describing the renormalization group evolution of mixing angles and of the CP phase for Dirac neutrinos. Radiative corrections to leptonic mixings are in this case enhanced compared to the quark mixings because the hierarchy of neutrino masses is milder and because the mixing angles are larger. The renormalization group effects are compared to the precision of current and future neutrino experiments. We find that, in the MSSM framework, radiative corrections of the mixing angles are for large tan β comparable to the precision of future experiments
Dirac neutrino masses from generalized supersymmetry breaking
International Nuclear Information System (INIS)
Demir, D.A.; Everett, L.L.; Langacker, P.
2007-12-01
We demonstrate that Dirac neutrino masses in the experimentally preferred range are generated within supersymmetric gauge extensions of the Standard Model with a generalized supersymmetry breaking sector. If the usual superpotential Yukawa couplings are forbidden by the additional gauge symmetry (such as a U(1) ' ), effective Dirac mass terms involving the ''wrong Higgs'' field can arise either at tree level due to hard supersymmetry breaking fermion Yukawa couplings, or at one-loop due to nonanalytic or ''nonholomorphic'' soft supersymmetry breaking trilinear scalar couplings. As both of these operators are naturally suppressed in generic models of supersymmetry breaking, the resulting neutrino masses are naturally in the sub-eV range. The neutrino magnetic and electric dipole moments resulting from the radiative mechanism also vanish at one-loop order. (orig.)
On oscillations of neutrinos with Dirac and Majorana masses
International Nuclear Information System (INIS)
Bilenky, S.M.; Hosek, J.; Petcov, S.T.; Bylgarska Akademiya na Naukite, Sofia)
1980-01-01
Pontecorvo neutrino beam oscillations are discussed assuming both Dirac and Majorana neutrino mass terms. It is proved that none of possible experiments on neutrino oscillations, including those on effects of CP violation, can distinguish between these two possibilities. Neutrino oscillations with concomitant Dirac and Majorana mass terms are also considered
The singular seesaw mechanism with hierarchical Dirac neutrino mass
International Nuclear Information System (INIS)
Chikira, Y.; Mimura, Y.
2000-01-01
The singular seesaw mechanism can naturally explain the atmospheric neutrino deficit by maximal oscillations between ν μ L and ν μ R . This mechanism can also induce three different scales of the neutrino mass squared differences, which can explain the neutrino deficits of three independent experiments (solar, atmospheric, and LSND) by neutrino oscillations. In this paper we show that realistic mixing angles among the neutrinos can be obtained by introducing a hierarchy in the Dirac neutrino mass. In the case where the Majorana neutrino mass matrix has rank 2, the solar neutrino deficit is explained by vacuum oscillations between ν e and ν τ . We also consider the case where the Majorana neutrino mass matrix has rank 1. In this case, the matter enhanced Mikheyev-Smirnov-Wolfenstein solar neutrino solution is preferred as the solution of the solar neutrino deficit. (orig.)
Two-loop Dirac neutrino mass and WIMP dark matter
Bonilla, Cesar; Ma, Ernest; Peinado, Eduardo; Valle, Jose W.F.
2018-01-01
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 enhan...
Common origin of neutrino mass, dark matter and Dirac leptogenesis
Energy Technology Data Exchange (ETDEWEB)
Borah, Debasish [Department of Physics, Indian Institute of Technology Guwahati, Assam 781039 (India); Dasgupta, Arnab, E-mail: dborah@iitg.ernet.in, E-mail: arnab.d@iopb.res.in [Institute of Physics, HBNI, Sachivalaya Marg, Bhubaneshwar 751005 (India)
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.
The B - L scotogenic models for Dirac neutrino masses
Energy Technology Data Exchange (ETDEWEB)
Wang, Weijian [North China Electric Power University, Department of Physics, Baoding (China); Wang, Ruihong [Hebei Agricultural University, College of Information Science and Technology, Baoding (China); Han, Zhi-Long [University of Jinan, School of Physics and Technology, Jinan, Shandong (China); Han, Jin-Zhong [Zhoukou Normal University, School of Physics and Telecommunications Engineering, Zhoukou, Henan (China)
2017-12-15
We construct the one-loop and two-loop scotogenic models for Dirac neutrino mass generation in the context of U(1){sub B-L} extensions of standard model. It is indicated that the total number of intermediate fermion singlets is uniquely fixed by the anomaly free condition and the new particles may have exotic B - L charges so that the direct SM Yukawa mass term anti ν{sub L}ν{sub R}φ{sup 0} and the Majorana mass term (m{sub N}/2)ν{sub R}{sup C}ν{sub R} are naturally forbidden. After the spontaneous breaking of the U(1){sub B-L} symmetry, the discrete Z{sub 2} or Z{sub 3} symmetry appears as the residual symmetry and gives rise to the stability of intermediate fields as DM candidates. Phenomenological aspects of lepton flavor violation, DM, leptogenesis and LHC signatures are discussed. (orig.)
The B-L scotogenic models for Dirac neutrino masses
Wang, Weijian; Wang, Ruihong; Han, Zhi-Long; Han, Jin-Zhong
2017-12-01
We construct the one-loop and two-loop scotogenic models for Dirac neutrino mass generation in the context of U(1)_{B-L} extensions of standard model. It is indicated that the total number of intermediate fermion singlets is uniquely fixed by the anomaly free condition and the new particles may have exotic B-L charges so that the direct SM Yukawa mass term \\bar{ν }_Lν _R\\overline{φ ^0} and the Majorana mass term (m_N/2)\\overline{ν _R^C}ν _R are naturally forbidden. After the spontaneous breaking of the U(1)_{B-L} symmetry, the discrete Z2 or Z3 symmetry appears as the residual symmetry and gives rise to the stability of intermediate fields as DM candidates. Phenomenological aspects of lepton flavor violation, DM, leptogenesis and LHC signatures are discussed.
International Nuclear Information System (INIS)
Joshipura, A.S.; Rindani, S.D.
1991-01-01
The consequences of imposing an exact L e +L τ -L μ symmetry on a 6x6 matrix describing neutrino masses are discussed. The presence of right-handed neutrinos avoids the need of introducing any SU(2) Higgs triplet. Hence the conflict with the CERN LEP data on the Z width found in earlier models with L e +L τ -L μ symmetry is avoided. The L e +L τ -L μ symmetry provides an interesting realization of a recent proposal of Glashow to accommodate the 17-keV Dirac neutrino in the SU(2)xU(1) theory. All the neutrinos in this model are Dirac particles. The solar-neutrino problem can be solved in an extension of the model which generates a large (∼10 -11 μ B ) magnetic moment for the electron neutrino
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.
Texture one zero Dirac neutrino mass matrix with vanishing determinant or trace condition
Singh, Madan
2018-06-01
In the light of non-zero and relatively large value of rector mixing angle (θ13), we have performed a detailed analysis of texture one zero neutrino mass matrix Mν in the scenario of vanishing determinant/trace conditions, assuming the Dirac nature of neutrinos. In both the scenarios, normal mass ordering is ruled out for all the six possibilities of Mν, however for inverted mass ordering, only two are found to be viable with the current neutrino oscillation data at 3σ confidence level. Numerical and some approximate analytical results are presented.
Quasi-Dirac neutrino oscillations
Anamiati, Gaetana; Fonseca, Renato M.; Hirsch, Martin
2018-05-01
Dirac neutrino masses require two distinct neutral Weyl spinors per generation, with a special arrangement of masses and interactions with charged leptons. Once this arrangement is perturbed, lepton number is no longer conserved and neutrinos become Majorana particles. If these lepton number violating perturbations are small compared to the Dirac mass terms, neutrinos are quasi-Dirac particles. Alternatively, this scenario can be characterized by the existence of pairs of neutrinos with almost degenerate masses, and a lepton mixing matrix which has 12 angles and 12 phases. In this work we discuss the phenomenology of quasi-Dirac neutrino oscillations and derive limits on the relevant parameter space from various experiments. In one parameter perturbations of the Dirac limit, very stringent bounds can be derived on the mass splittings between the almost degenerate pairs of neutrinos. However, we also demonstrate that with suitable changes to the lepton mixing matrix, limits on such mass splittings are much weaker, or even completely absent. Finally, we consider the possibility that the mass splittings are too small to be measured and discuss bounds on the new, nonstandard lepton mixing angles from current experiments for this case.
Energy Technology Data Exchange (ETDEWEB)
Campagne, J E
1995-04-01
This work deals with the Dirac or Majorana nature and mass effects on the neutrino behaviour. In the first part of this study are given the Dirac equation properties and the Majorana neutrino definition. As the difference between a Dirac and a Majorana neutrino has only a sense if their masses are not equal to zero, the second part presents a generalization of the Dirac mass term and the different ways to generate a neutrino mass. Several comparisons are made in the third part between quarks and leptons families mixtures which are linked intimately to masses generation. The fourth part gives an example of masses possible values and neutrinos particles mixtures matrix elements predicting. The neutrino electromagnetic and weak interactions are then considered as well as the neutrinos production by the neutral currents. The charged currents are however better to discriminate the Dirac or Majorana nature. The neutrinos propagation in the matter and in the vacuum are analyzed (the case of neutrino oscillations more particularly) under the result of recent experimental observations. At last, are presented the evaluation of neutrino mass (if it exists) through the analysis of double beta decay and the sensibility of future experiments. (O.L.). 164 refs., 73 figs., 20 tabs.
International Nuclear Information System (INIS)
Strobel, E.L.
1985-01-01
Given the many conflicting experimental results, examination is made of the neutrino mass matrix in order to determine possible masses and mixings. It is assumed that the Dirac mass matrix for the electron, muon, and tau neutrinos is similar in form to those of the quarks and charged leptons, and that the smallness of the observed neutrino masses results from the Gell-Mann-Ramond-Slansky mechanism. Analysis of masses and mixings for the neutrinos is performed using general structures for the Majorana mass matrix. It is shown that if certain tentative experimental results concerning the neutrino masses and mixing angles are confirmed, significant limitations may be placed on the Majorana mass matrix. The most satisfactory simple assumption concerning the Majorana mass matrix is that it is approximately proportional to the Dirac mass matrix. A very recent experimental neutrino mass result and its implications are discussed. Some general properties of matrices with structure similar to the Dirac mass matrices are discussed
Dirac neutrinos and hybrid inflation from string theory
International Nuclear Information System (INIS)
Antusch, Stefan; Eyton-Williams, Oliver J.; King, Steve F.
2005-01-01
We consider a possible scenario for the generation of Dirac neutrino masses motivated by type-I string theory. The smallness of the neutrino Yukawa couplings is explained by an anisotropic compactification with one compactification radius larger than the others. In addition to this we utilise small Yukawa couplings to develop strong links between the origin of neutrino masses and the physics driving inflation. We construct a minimal model which simultaneously accommodates small Dirac neutrino masses leading to bi-large lepton mixing as well as an inflationary solution to the strong CP and to the μ problem
International Nuclear Information System (INIS)
Kayser, B.
1992-01-01
After arguing that we should be looking for evidence of neutrino mass, we illustrate the possible consequences of neutrino mass and mixing. We then turn to the question of whether neutrinos are their own antiparticles, and to the process which may answer this question: neutrinoless double beta decay. Next, we review the proposed Mikheyev-Smirnov-Wolfenstein solution to the solar neutrino problem, and discuss models which can generate neutrino electromagnetic moments large enough to play a role in the sun. Finally, we consider how the possible 17 keV neutrino, if real, would fit in with everything we know about neutrinos. (orig.)
A model for pseudo-Dirac neutrinos: leptogenesis and ultra-high energy neutrinos
Energy Technology Data Exchange (ETDEWEB)
Ahn, Y.H. [Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS),Daejeon, 34051 (Korea, Republic of); Kang, Sin Kyu [Insitute for Convergence Fundamental Study, School of Liberal Arts, Seoul-Tech.,Seoul, 01811 (Korea, Republic of); Kim, C.S. [Dept. of Physics and IPAP, Yonsei University,Seoul, 120-749 (Korea, Republic of)
2016-10-18
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.
International Nuclear Information System (INIS)
Branco, G.C.; Senjanovic, G.
1978-01-01
We investigate the question of neutrino mass in theories in which neutrinos are four-component Dirac particles. Our analysis is done in the framework of left-right--symmetric theories. The requirement of calculability and natural smallness of neutrino mass leads to the following constraints: (i) left and right charged weak currents must be ''orthogonal'' to each other, and (ii) there should be no W/sub L/-W/sub R/ mixing at the three level. Finally, we exhibit a model in which, due to the existence of an unbroken symmetry of the total Lagrangian, the electron and muon neutrinos remain massless to all orders in perturbation theory
Kayser, Boris
1988-01-01
This is a review article about the most recent developments on the field of neutrino mass. The first part of the review introduces the idea of neutrino masses and mixing angles, summarizes the most recent experimental data then discusses the experimental prospects and challenges in this area. The second part of the review discusses the implications of these results for particle physics and cosmology, including the origin of neutrino mass, the see-saw mechanism and sequential dominance, and la...
International Nuclear Information System (INIS)
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
Dark energy from pNGB mediated Dirac neutrino condensate
Directory of Open Access Journals (Sweden)
Ujjal Kumar Dey
2018-03-01
Full Text Available We consider an extension of the Standard Model that provide an unified description of eV scale neutrino mass and dark energy. An explicit model is presented by augmenting the Standard Model with an SU(2L doublet scalar, a singlet scalar and right handed neutrinos where all of them are assumed to be charged under a global U(1X symmetry. A light pseudo-Nambu–Goldstone Boson, associated with the spontaneously broken U(1X symmetry, acts as a mediator of an attractive force leading to a Dirac neutrino condensate, with large correlation length, and a non-zero gap in the right range providing a cosmologically feasible dark energy scenario. The neutrino mass is generated through the usual Dirac seesaw mechanism. Parameter space, reproducing viable dark energy scenario while having neutrino mass in the right ballpark, is presented.
Understanding neutrino masses and mixings
Indian Academy of Sciences (India)
various possible oscillation solutions to the solar neutrino puzzle. It seems .... A first hint of this new ingredient came from the observation of Weinberg that if ..... Using the discussion of the above paragraph, the Dirac mass of the neutrino as .... that contributes to charged fermion masses, one can write the quark and lepton.
Symplectic symmetry of the neutrino mass for many neutrino flavors
International Nuclear Information System (INIS)
Oeztuerk, N.; Ankara Univ.
2001-01-01
The algebraic structure of the neutrino mass Hamiltonian is presented for two neutrino flavors considering both Dirac and Majorana mass terms. It is shown that the algebra is Sp(8) and also discussed how the algebraic structure generalizes for the case of more than two neutrino flavors. (orig.)
Geometric phase of neutrinos: Differences between Dirac and Majorana neutrinos
Capolupo, A.; Giampaolo, S. M.; Hiesmayr, B. C.; Vitiello, G.
2018-05-01
We analyze the non-cyclic geometric phase for neutrinos. We find that the geometric phase and the total phase associated to the mixing phenomenon provide a theoretical tool to distinguish between Dirac and Majorana neutrinos. Our results hold for neutrinos propagating in vacuum and through the matter. We feed the values of the experimental parameters in our formulas in order to make contact with experiments. Although it remains an open question how the geometric phase of neutrinos could be detected, our theoretical results may open new scenarios in the investigation of the neutrino nature.
Seesaw roadmap to neutrino mass and dark matter
Centelles Chuliá, Salvador; Srivastava, Rahul; Valle, José W. F.
2018-06-01
We describe the many pathways to generate Majorana and Dirac neutrino mass through generalized dimension-5 operators a la Weinberg. The presence of new scalars beyond the Standard Model Higgs doublet implies new possible field contractions, which are required in the case of Dirac neutrinos. We also notice that, in the Dirac neutrino case, the extra symmetries needed to ensure the Dirac nature of neutrinos can also be made responsible for stability of dark matter.
Neutrino masses and neutrino oscillations
Di Lella, L
2000-01-01
These lectures review direct measurements of neutrino masses and the status of neutrino oscillation searches using both natural neutrino sources (the Sun and cosmic rays interacting in the Earth atmosphere) and artificial neutrinos (produced by nuclear reactors and accelerators). Finally, future experiments and plans are presented. (68 refs).
Planck-scale physics and neutrino masses
International Nuclear Information System (INIS)
Akhmedov, E.Kh.; Senjanovic, G.; Berezhiani, Z.G.
1992-05-01
We discuss gravitationally induced masses and mass splittings of Majorana, Zeldovich-Konopinski-Mahmoud and Dirac neutrinos. Among other implications, these effects can provide a solution of the solar neutrino puzzle. In particular, we show how this may work in the 17 keV neutrino picture. (author). 18 refs
Neutrino masses and oscillations
Energy Technology Data Exchange (ETDEWEB)
Smirnov, A Yu
1996-11-01
New effects related to refraction of neutrinos in different media are reviewed and implication of the effects to neutrino mass and mixing are discussed. Patterns of neutrino masses and mixing implied by existing hints/bounds are described. Recent results on neutrino mass generation are presented. They include neutrino masses in SO(10) GUT`s and models with anomalous U(1), generation of neutrino mass via neutrino-neutralino mixing, models of sterile neutrino. (author). 95 refs, 9 figs.
Gauge Trimming of Neutrino Masses
International Nuclear Information System (INIS)
Chen, Mu-Chun; de Gouvea, Andre; Dobrescu, Bogdan A.
2006-01-01
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
Can neutrino-electron scattering tell us whether neutrinos are Dirac or Majorana particles?
International Nuclear Information System (INIS)
Kayser, B.
1988-04-01
There has recently been interest in the possibility that neutrino-electron scattering experiments could determine whether neutrinos are Dirac or Majorana particles by providing information on their electromagnetic structure. We try to explain why studies of neutrino electromagnetic structure actually cannot distinguish between Dirac and Majorana neutrinos. 9 refs
Neutrino masses and family replication
International Nuclear Information System (INIS)
Hung, P.Q.
1999-01-01
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 'very heavy' fourth neutrino and three almost degenerate light neutrinos whose masses are all of the Dirac type. copyright 1999 The American Physical Society
Thermal dark matter through the Dirac neutrino portal
Batell, Brian; Han, Tao; McKeen, David; Haghi, Barmak Shams Es
2018-04-01
We study a simple model of thermal dark matter annihilating to standard model neutrinos via the neutrino portal. A (pseudo-)Dirac sterile neutrino serves as a mediator between the visible and the dark sectors, while an approximate lepton number symmetry allows for a large neutrino Yukawa coupling and, in turn, efficient dark matter annihilation. The dark sector consists of two particles, a Dirac fermion and complex scalar, charged under a symmetry that ensures the stability of the dark matter. A generic prediction of the model is a sterile neutrino with a large active-sterile mixing angle that decays primarily invisibly. We derive existing constraints and future projections from direct detection experiments, colliders, rare meson and tau decays, electroweak precision tests, and small scale structure observations. Along with these phenomenological tests, we investigate the consequences of perturbativity and scalar mass fine tuning on the model parameter space. A simple, conservative scheme to confront the various tests with the thermal relic target is outlined, and we demonstrate that much of the cosmologically-motivated parameter space is already constrained. We also identify new probes of this scenario such as multibody kaon decays and Drell-Yan production of W bosons at the LHC.
Distinguishing Dirac/Majorana sterile neutrinos at the LHC
International Nuclear Information System (INIS)
Dib, Claudio O.; Zhang, Jue
2016-06-01
We study the purely leptonic decays of W ± → e ± e ± μ -+ ν and μ ± μ ± e -+ ν produced at the LHC, induced by sterile neutrinos with mass m N below M W in the intermediate state. Since the final state neutrino escapes detection, one cannot tell whether this process violates lepton number, what would indicate a Majorana character for the intermediate sterile neutrino. Our study shows that when the sterile neutrino mixings with electrons and muons are different enough, one can still discriminate between the Dirac and Majorana character of this intermediate neutrino by simply counting and comparing the above decay rates. After performing collider simulations and statistical analysis, we find that at the 14 TeV LHC with an integrated luminosity of 3000 fb -1 , for two benchmark scenarios m N =20 GeV and 50 GeV, at least a 3σ level of exclusion on the Dirac case can be achieved for disparities as mild as e.g. vertical stroke U Ne vertical stroke 2 <0.7 vertical stroke U Nμ vertical stroke 2 or vertical stroke U Nμ vertical stroke 2 <0.7 vertical stroke U Ne vertical stroke 2 , provided that vertical stroke U Ne vertical stroke 2 , vertical stroke U Nμ vertical stroke 2 are both above ∝2 x 10 -6 .
International Nuclear Information System (INIS)
Anon.
1986-01-01
Postulated in the early days of quantum mechanics by Wolfgang Pauli to make energy-momentum conservation in nuclear beta decay come out right, the neutrino has never strayed far from physicists' attention. The Moriond Workshop on Massive Neutrinos in Particle Physics and Astrophysics held recently in the French Alps showed that more than half a century after Pauli's prediction, the neutrino stubbornly refuses to yield up all its secrets
Energy Technology Data Exchange (ETDEWEB)
Anon.
1986-04-15
Postulated in the early days of quantum mechanics by Wolfgang Pauli to make energy-momentum conservation in nuclear beta decay come out right, the neutrino has never strayed far from physicists' attention. The Moriond Workshop on Massive Neutrinos in Particle Physics and Astrophysics held recently in the French Alps showed that more than half a century after Pauli's prediction, the neutrino stubbornly refuses to yield up all its secrets.
DEFF Research Database (Denmark)
Schechter, J.; Shahid, M. N.
2012-01-01
We discuss the possibility of using experiments timing the propagation of neutrino beams over large distances to help determine the absolute masses of the three neutrinos.......We discuss the possibility of using experiments timing the propagation of neutrino beams over large distances to help determine the absolute masses of the three neutrinos....
Naturally light Dirac neutrino in Left-Right Symmetric Model
Energy Technology Data Exchange (ETDEWEB)
Borah, Debasish [Department of Physics, Indian Institute of Technology Guwahati, Assam-781039 (India); Dasgupta, Arnab, E-mail: dborah@iitg.ernet.in, E-mail: arnab.d@iopb.res.in [Institute of Physics, HBNI, Sachivalaya Marg, Bhubaneshwar-751005 (India)
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 Z {sub 2} 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 N {sub eff}=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.
Neutrino mass and the solar neutrino problem
International Nuclear Information System (INIS)
Wolfenstein, L.
1987-01-01
Theoretical ideas about neutrino mass based on grand-unified theories are reviewed. These give the see-saw formula in which neutrino mass is inversely proportional to a large mass scale M. For M between 10/sup 11/ and 10/sup 15/ Gev the study of solar neutrinos appears to be the best probe of neutrino masses and mixings
Distinguishing Dirac/Majorana sterile neutrinos at the LHC
Energy Technology Data Exchange (ETDEWEB)
Dib, Claudio O. [Univ. Tecnica Federico Santa Maria, Valparaiso (Chile). CCTVal y Dept. of Physics; Kim, C.S. [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Physics and IPAP; Wang, Kechen [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Zhang, Jue [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics
2016-06-15
We study the purely leptonic decays of W{sup ±} → e{sup ±}e{sup ±}μ{sup -+}ν and μ{sup ±}μ{sup ±}e{sup -+}ν produced at the LHC, induced by sterile neutrinos with mass m{sub N} below M{sub W} in the intermediate state. Since the final state neutrino escapes detection, one cannot tell whether this process violates lepton number, what would indicate a Majorana character for the intermediate sterile neutrino. Our study shows that when the sterile neutrino mixings with electrons and muons are different enough, one can still discriminate between the Dirac and Majorana character of this intermediate neutrino by simply counting and comparing the above decay rates. After performing collider simulations and statistical analysis, we find that at the 14 TeV LHC with an integrated luminosity of 3000 fb{sup -1}, for two benchmark scenarios m{sub N}=20 GeV and 50 GeV, at least a 3σ level of exclusion on the Dirac case can be achieved for disparities as mild as e.g. vertical stroke U{sub Ne} vertical stroke {sup 2}<0.7 vertical stroke U{sub Nμ} vertical stroke {sup 2} or vertical stroke U{sub Nμ} vertical stroke {sup 2}<0.7 vertical stroke U{sub Ne} vertical stroke {sup 2}, provided that vertical stroke U{sub Ne} vertical stroke {sup 2}, vertical stroke U{sub Nμ} vertical stroke {sup 2} are both above ∝2 x 10{sup -6}.
Observable lepton number violation with predominantly Dirac nature of active neutrinos
Energy Technology Data Exchange (ETDEWEB)
Borah, Debasish [Department of Physics, Indian Institute of Technology Guwahati,Assam-781039 (India); Dasgupta, Arnab [Institute of Physics, HBNI,Sachivalaya Marg, Bhubaneshwar-751005 (India)
2017-01-17
We study a specific version of SU(2){sub R}×SU(2){sub L}×U(1){sub B−L} models extended by discrete symmetries where the new physics sector responsible for tiny neutrino masses at leading order remains decoupled from the new physics sector that can give rise to observable signatures of lepton number violation such as neutrinoless double beta decay. More specifically, the dominant contribution to light neutrino masses comes from a one-loop Dirac mass. At higher loop level, a tiny Majorana mass also appears which remains suppressed by many order of magnitudes in comparison to the Dirac mass. Such a model where the active neutrinos are predominantly of Dirac type, also predicts observable charged lepton flavour violation like μ→3e,μ→eγ and multi-component dark matter.
On the Hierarchy of Neutrino Masses
International Nuclear Information System (INIS)
Jezabek, M.; Urban, P.
2002-01-01
We present a model of neutrino masses combining the seesaw mechanism and strong Dirac mass hierarchy and at the same time exhibiting a significantly reduced hierarchy at the level of active neutrino masses. The heavy Majorana masses are assumed to be degenerate. The suppression of the hierarchy is due to a symmetric and unitary operator R whose role is discussed. The model gives realistic mixing and mass spectrum. The mixing of atmospheric neutrinos is attributed to the charged lepton sector whereas the mixing of solar neutrinos is due to the neutrino sector. Small U e3 is a consequence of the model. The masses of the active neutrinos are given by μ 3 ≅ √(Δm 2 O ) and μ 1 /μ 2 = ≅ tan 2 (θ O ). (author)
Leptogenesis and neutrino masses
International Nuclear Information System (INIS)
Pluemacher, M.
2004-01-01
Thermal leptogenesis explains the baryon asymmetry of the universe by the out-of-equilibrium decays of heavy right-handed neutrinos. In the minimal seesaw model this leads to interesting implications for light neutrino properties. In particular, quasi-degenerate light neutrino masses are incompatible with leptogenesis. An upper bound on light neutrino masses of 0.1 eV can be derived, which will be tested by forthcoming laboratory experiments and cosmology. (author)
Reconstructing Neutrino Mass Spectrum
Smirnov, A. Yu.
1999-01-01
Reconstruction of the neutrino mass spectrum and lepton mixing is one of the fundamental problems of particle physics. In this connection we consider two central topics: (i) the origin of large lepton mixing, (ii) possible existence of new (sterile) neutrino states. We discuss also possible relation between large mixing and existence of sterile neutrinos.
International Nuclear Information System (INIS)
Wolfenstein, L.
1991-01-01
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 ν τ , (2) a 30 ev ν τ making up the dark matter, (3) a 10 -3 ev ν μ to solve the solar neutrino problem, and (4) a three-neutrino MSW solution
Complex scaling and residual flavour symmetry in the neutrino mass ...
Indian Academy of Sciences (India)
Probir Roy
2017-10-09
Oct 9, 2017 ... Leptonic Dirac CP violation must be maximal while atmospheric neutrino mixing need not be exactly maximal. Each of the two Majorana phases, to be probed by the search for 0νββ decay, has to be zero or π and a normal neutrino mass hierarchy is allowed. Keywords. Neutrinos; residual flavour symmetry; ...
Neutrino mass, a status report
International Nuclear Information System (INIS)
Robertson, R.G.H.
1993-01-01
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
Minimalistic Neutrino Mass Model
De Gouvêa, A; Gouvea, Andre de
2001-01-01
We consider the simplest model which solves the solar and atmospheric neutrino puzzles, in the sense that it contains the smallest amount of beyond the Standard Model ingredients. The solar neutrino data is accounted for by Planck-mass effects while the atmospheric neutrino anomaly is due to the existence of a single right-handed neutrino at an intermediate mass scale between 10^9 GeV and 10^14 GeV. Even though the neutrino mixing angles are not exactly predicted, they can be naturally large, which agrees well with the current experimental situation. Furthermore, the amount of lepton asymmetry produced in the early universe by the decay of the right-handed neutrino is very predictive and may be enough to explain the current baryon-to-photon ratio if the right-handed neutrinos are produced out of thermal equilibrium. One definitive test for the model is the search for anomalous seasonal effects at Borexino.
International Nuclear Information System (INIS)
Robertson, R.G.H.
1985-01-01
Direct experimental information of neutrino mass as derived from the study of nuclear and elementary-particle weak decays is reviewed. Topics include tritium beta decay; the 3 He-T mass difference; electron capture decay of 163 Ho and 158 Tb; and limits on massive neutrinos from cosmology. 38 references
Unified picture for Dirac neutrinos, dark matter, dark energy and matter–antimatter asymmetry
Gu, Pei-Hong
2008-01-01
We propose a unified scenario to generate the masses of Dirac neutrinos and cold dark matter at the TeV scale, understand the origin of dark energy and explain the matter-antimatter asymmetry of the universe. This model can lead to significant impact on the Higgs searches at LHC.
Radiative Majorana Neutrino Masses
Hou, Wei-Shu; Wong, Gwo-Guang
1994-01-01
We present new radiative mechanisms for generating Majorana neutrino masses, within an extension of the standard model that successfully generates radiative charged lepton masses, order by order, from heavy sequential leptons. Only the new sequential neutral lepton has a right-handed partner, and its Majorana mass provides the seed for Majorana neutrino mass generation. Saturating the cosmological bound of $50$ eV with $m_{\
On the possibilities of distinguishing Dirac from Majorana neutrinos
International Nuclear Information System (INIS)
Zralek, M.
1997-01-01
The problem if existing neutrinos are Dirac or Majorana particles is considered in a very pedagogical way. After a few historical remarks we recall the theoretical description of neutral spin 1/2 particles, emphasizing the difference between chirality and helicity which is important in our discussion. Next we describe the properties of neutrinos in the cases when their interactions are given by the standard model and by its extensions (massive neutrinos, right-handed currents, electromagnetic neutrino interaction, interaction with scalar particles). Various processes where the different nature of neutrinos could in principle be visible are reviewed. We clear up misunderstandings which have appeared in last suggestions how to distinguish both types of neutrinos. (author)
Lesgourgues, Julien
2012-01-01
Neutrinos can play an important role in the evolution of the Universe, modifying some of the cosmological observables. In this contribution we summarize the main aspects of cosmological relic neutrinos and we describe how the precision of present cosmological data can be used to learn about neutrino properties, in particular their mass, providing complementary information to beta decay and neutrinoless double-beta decay experiments. We show how the analysis of current cosmological observations, such as the anisotropies of the cosmic microwave background or the distribution of large-scale structure, provides an upper bound on the sum of neutrino masses of order 1 eV or less, with very good perspectives from future cosmological measurements which are expected to be sensitive to neutrino masses well into the sub-eV range.
International Nuclear Information System (INIS)
Robertson, R.G.H.
1989-01-01
The current status of the experimental search for neutrino mass is reviewed, with emphasis on direct kinematic methods. Simpson and Hime report finding new evidence for a 17-keV neutrino in the β decay of 3 H and 35 S. The situation concerning the electron neutrino mass as measured in tritium beta decay has not changed significantly in the last two years. We discuss the ''model independent'' lower limit of 17 eV obtained by the ITEP group in light of existing data on the 3 H-- 3 He mass difference. 42 refs., 1 fig., 1 tab
International Nuclear Information System (INIS)
Fogli, G.
1998-01-01
The paper presents an analysis of the solar neutrino problem in terms of both Mikheyev-Smirnov-Wolfenstein (MSW) and vacuum neutrino oscillations, with the inclusion of the data collected by the SuperKamiokande experiment during 306.3 days of operation. In particular, the observed energy spectrum of the recoil electrons from 8 B neutrino scattering is discussed in detail and used to constrain the mass-mixing parameter space. Going to the atmospheric neutrino anomaly, the paper performs both a two- and three-flavor analysis of the most recent SuperKamiokande atmospheric neutrino data. The variations of the zenith distributions of ν events in the presence of flavor oscillations are investigated. It is seen that fits to the SK data, with and without the addition of the CHOOZ constrains, strongly limit the parameter space. Detailed bounds in triangle graphs are reported
International Nuclear Information System (INIS)
Robertson, R.G.H.
1989-01-01
Some recent developments in the experimental search for neutrino mass are discussed. Simpson and Hime report finding new evidence for a 17-keV neutrino in the β decay of 3 H and 35 S. New data from Los Alamos on the electron neutrino mass as measured in tritium beta decay give an upper limit of 13.5 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. 38 refs., 1 figs., 2 tabs
17 keV and 30 eV Dirac neutrinos and a techniphoton
International Nuclear Information System (INIS)
Holdom, B.
1985-01-01
We consider four flavors of left-handed Weyl neutrinos forming two Dirac masses, of order 17 keV and 30 eV. The symmetry Lsub(e)+Lsub(tau)-Lsub(μ)-Lsub(lambda) ensures this form of the mass matrix and consistency with experiments. We show how it arises in a technicolor context. The structure of the model can incorporate a techniphoton, an unbroken U(1) gauge symmetry of technifermions, and this makes a 17 keV neutrino cosmologically unstable. (orig.)
Relic right-handed Dirac neutrinos and implications for detection of cosmic neutrino background
Directory of Open Access Journals (Sweden)
Jue Zhang
2016-02-01
Full Text Available It remains to be determined experimentally if massive neutrinos are Majorana or Dirac particles. In this connection, it has been recently suggested that the detection of cosmic neutrino background of left-handed neutrinos νL and right-handed antineutrinos ν‾R in future experiments of neutrino capture on beta-decaying nuclei (e.g., νe+H3→He3+e− for the PTOLEMY experiment is likely to distinguish between Majorana and Dirac neutrinos, since the capture rate is twice larger in the former case. In this paper, we investigate the possible impact of right-handed neutrinos on the capture rate, assuming that massive neutrinos are Dirac particles and both right-handed neutrinos νR and left-handed antineutrinos ν‾L can be efficiently produced in the early Universe. It turns out that the capture rate can be enhanced at most by 28% due to the presence of relic νR and ν‾L with a total number density of 95 cm−3, which should be compared to the number density 336 cm−3 of cosmic neutrino background. The enhancement has actually been limited by the latest cosmological and astrophysical bounds on the effective number of neutrino generations Neff=3.14−0.43+0.44 at the 95% confidence level. For illustration, two possible scenarios have been proposed for thermal production of right-handed neutrinos in the early Universe.
Search for Dirac and Majorana sterile neutrinos in trilepton events at the LHC
Energy Technology Data Exchange (ETDEWEB)
Dib, Claudio O. [Univ. Tecnica Federico Santa Maria, Valparaiso (Chile). CCTVal y Dept. of Physics; Kim, C.S. [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Physics and IPAP; Wang, Kechen [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Chinese Academy of Sciences, Beijing (China). Center for Future High Energy Physics
2017-03-15
Heavy sterile neutrinos with masses below M{sub W} can induce trilepton events at the 14 TeV LHC through purely leptonic W decays of W{sup ±}→e{sup ±}e{sup ±}μ{sup -+}ν and μ{sup ±}μ{sup ±}e{sup -+}ν where the heavy neutrino will be in an intermediate state on its mass shell. Discovery and exclusion limits for the heavy neutrinos are found using both Cut-and-Count (CC) and a Multi-Variate Analysis (MVA) methods in this study. We also show that it is possible to discriminate between a Dirac and a Majorana heavy neutrino, even when lepton number conservation cannot be directly tested due to unobservability of the final state neutrino. This discrimination is done by exploiting a combined set of kinematic observables that differ between the Majorana vs. Dirac cases. We find that the MVA method can greatly enhance the discovering and discrimination limits in comparison with the CC method. With an integrated luminosity of 3000 fb{sup -1}, sterile neutrinos can be found with 5σ significance if heavy-to-light neutrino mixings vertical stroke U{sub Ne} vertical stroke {sup 2}∝ vertical stroke U{sub Nμ} vertical stroke {sup 2}∝10{sup -6}, while the Majorana vs. Dirac type can be distinguished if vertical stroke U{sub Ne} vertical stroke {sup 2}∝ vertical stroke U{sub Nμ} vertical stroke {sup 2}∝10{sup -5} or even vertical stroke U{sub Nl} vertical stroke {sup 2}∝10{sup -6} if one of mixing elements can be at least one order of magnitude smaller than the other.
Search for Dirac and Majorana sterile neutrinos in trilepton events at the LHC
International Nuclear Information System (INIS)
Dib, Claudio O.; Kim, C.S.; Wang, Kechen; Chinese Academy of Sciences, Beijing
2017-03-01
Heavy sterile neutrinos with masses below M_W can induce trilepton events at the 14 TeV LHC through purely leptonic W decays of W"±→e"±e"±μ"-"+ν and μ"±μ"±e"-"+ν where the heavy neutrino will be in an intermediate state on its mass shell. Discovery and exclusion limits for the heavy neutrinos are found using both Cut-and-Count (CC) and a Multi-Variate Analysis (MVA) methods in this study. We also show that it is possible to discriminate between a Dirac and a Majorana heavy neutrino, even when lepton number conservation cannot be directly tested due to unobservability of the final state neutrino. This discrimination is done by exploiting a combined set of kinematic observables that differ between the Majorana vs. Dirac cases. We find that the MVA method can greatly enhance the discovering and discrimination limits in comparison with the CC method. With an integrated luminosity of 3000 fb"-"1, sterile neutrinos can be found with 5σ significance if heavy-to-light neutrino mixings vertical stroke U_N_e vertical stroke "2∝ vertical stroke U_N_μ vertical stroke "2∝10"-"6, while the Majorana vs. Dirac type can be distinguished if vertical stroke U_N_e vertical stroke "2∝ vertical stroke U_N_μ vertical stroke "2∝10"-"5 or even vertical stroke U_N_l vertical stroke "2∝10"-"6 if one of mixing elements can be at least one order of magnitude smaller than the other.
Baryogenesis and neutrino masses
International Nuclear Information System (INIS)
Peccei, R.D.
1992-01-01
The erasure of any preexisting B+L asymmetry in the universe in its late stages suggests that the B asymmetry observed today either originated at the electroweak scale or it arose from an original L asymmetry. For the latter case to be viable either neutrino masses are much below the eV scale or the L asymmetry itself is generated at an intermediate scale. Several features of the generation of a B asymmetry via an L asymmetry are discussed, including the interesting possibility that the present baryon asymmetry in the universe originates as a result of CP violating phases in the neutrino mass matrix
Towards absolute neutrino masses
Energy Technology Data Exchange (ETDEWEB)
Vogel, Petr [Kellogg Radiation Laboratory 106-38, Caltech, Pasadena, CA 91125 (United States)
2007-06-15
Various ways of determining the absolute neutrino masses are briefly reviewed and their sensitivities compared. The apparent tension between the announced but unconfirmed observation of the 0{nu}{beta}{beta} decay and the neutrino mass upper limit based on observational cosmology is used as an example of what could happen eventually. The possibility of a 'nonstandard' mechanism of the 0{nu}{beta}{beta} decay is stressed and the ways of deciding which of the possible mechanisms is actually operational are described. The importance of the 0{nu}{beta}{beta} nuclear matrix elements is discussed and their uncertainty estimated.
Dirac equation in a de Sitter expansion for massive neutrinos from modern Kaluza-Klein theory
International Nuclear Information System (INIS)
Sánchez, Pablo Alejandro; Anabitarte, Mariano; Bellini, Mauricio
2012-01-01
Using the modern Kaluza-Klein theory of gravity (or the Induced Matter theory), we study the Dirac equation for massive neutrinos on a de Sitter background metric from a 5D Riemann-flat (and hence Ricci-flat) extended de Sitter metric, on which is defined the vacuum for test massless 1/2-spin neutral fields minimally coupled to gravity and free of any other interactions. We obtain that the effective 4D masses of the neutrinos can only take three possible values, which are related to the (static) foliation of the fifth and noncompact extra dimension.
Damanik, Asan
2018-03-01
Neutrino mass sum-rele is a very important research subject from theoretical side because neutrino oscillation experiment only gave us two squared-mass differences and three mixing angles. We review neutrino mass sum-rule in literature that have been reported by many authors and discuss its phenomenological implications.
Direct neutrino mass measurements
Energy Technology Data Exchange (ETDEWEB)
Weinheimer, Christian, E-mail: weinheimer@uni-muenster.de [Westfaelische Wilhelms-Universitaet, Institut fuer Kernphysik (Germany)
2013-03-15
Direct neutrino mass experiments are complementary to searches for neutrinoless double {beta}-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/c{sup 2} . The KATRIN experiment under construction will improve the neutrino mass sensitivity down to 200 meV/c{sup 2} 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 {beta}-decay experiments cryo-bolometers investigating the endpoint region of {sup 187}Re {beta}-decay or the electron capture of {sup 163}Ho are being developed. This article briefly reviews the current status of the direct neutrino mass measurements.
International Nuclear Information System (INIS)
Mohapatra, R N
2004-01-01
Recent neutrino oscillation experiments have yielded valuable information on the nature of neutrino masses and mixings and qualify as the first evidence for physics beyond the standard model. Even though we are far from a complete understanding of the new physics implied by them, there are many useful hints. As the next precision era in neutrino physics is about to be launched, we review the physics of neutrino mass: what we have learned and what we are going to learn
Neutrino mass as the probe of intermediate mass scales
International Nuclear Information System (INIS)
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 β decay, where observation would provide a crucial test of the model, and rare muon decays such as μ → eγ and μ → 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 as the probe of intermediate mass scales
Energy Technology Data Exchange (ETDEWEB)
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.
Systems of neutrinos with mass
International Nuclear Information System (INIS)
Groot, S.R. de
1984-01-01
From the formalism of relativistic kinetic theory and the weak interaction Lagrangian the volume viscosity of a massive neutrino system is derived. Its value is calculated as a function of the neutrino mass and the temperature. Its role in the way of expanding or contraction of neutrino clouds in the universe is discussed. (Author) [pt
Neutrino masses and spontaneously broken flavor symmetries
International Nuclear Information System (INIS)
Staudt, Christian
2014-01-01
We study the phenomenology of supersymmetric flavor models. We show how the predictions of models based on spontaneously broken non-Abelian discrete flavor symmetries are altered when we include so-called Kaehler corrections. Furthermore, we discuss anomaly-free discrete R symmetries which are compatible with SU(5) unification. We find a set of symmetries compatible with suppressed Dirac neutrino masses and a unique symmetry consistent with the Weinberg operator. We also study a pseudo-anomalous U(1) R symmetry which explains the fermion mass hierarchies and, when amended with additional singlet fields, ameliorates the fine-tuning problem.
Dirac equation for massive neutrinos in a Schwarzschild-de Sitter spacetime from a 5D vacuum
International Nuclear Information System (INIS)
Sánchez, Pablo Alejandro; Anabitarte, Mariano; Bellini, Mauricio
2011-01-01
Starting from a Dirac equation for massless neutrino in a 5D Ricci-flat background metric, we obtain the effective 4D equation for massive neutrino in a Schwarzschild-de Sitter (SdS) background metric from an extended SdS 5D Ricci-flat metric. We use the fact that the spin connection is defined to an accuracy of a vector, so that the covariant derivative of the spinor field is strongly dependent of the background geometry. We show that the mass of the neutrino can be induced from the extra space-like dimension.
Is neutrino produced in standard weak interactions a Dirac or Majorana particle?
International Nuclear Information System (INIS)
Beshtoev, Kh.M.
2010-01-01
This work considers the following problem: what type (Dirac or Majorana) of neutrinos is produced in standard weak interactions? It is concluded that only Dirac neutrinos but not Majorana neutrinos can be produced in these interactions. Then neutrino interacts with W ± and Z bosons but neutrinoless double beta decay is absent. It means that this neutrino will be produced in another type of interaction. Namely, Majorana neutrino will be produced in the interaction which differentiates spin projections but cannot differentiate neutrino (particle) from antineutrino (antiparticle). Then neutrino will interact with W ± bosons and neutrinoless double beta decay will arise. But interaction with Z boson will be absent. Such an interaction has not been discovered yet. Therefore, experiments with very high precision are important to detect the neutrinoless double decays if they are realized in the Nature
Radiationless Zitterbewegung of Dirac particles and mass formula
International Nuclear Information System (INIS)
Noboru Hokkyo.
1987-06-01
The Zitterbewegung of the Dirac particle is given a visual representation by solving the two-component difference form of the Dirac equation. It is seen that the space-time trajectory of a Dirac particle can be pictured as a correlated whole of a network of zigzags of left- and right-handed chiral neutrino-like line elements. These zigzags can feel the curl of the external electromagnetic vector potential and give rise to the spin magnetic interaction, confirming Schroedinger's earlier intuitive picture of the spin as the orbital angular momentum of the Zitterbewegung. The network of zigzags associated with an electron splits and reunites in passing through the slits in the electron beam interference experiment. It is proposed to interpret Nambu's empirical mass formula m n =(n/2)137m e =(n/2)((h/2π)/cL), n=integer, as a radiationless condition for the Zitterbewegung of the hadronic Dirac particle of the linear spatial extension of the order of the classical electron radius L=e 2 /m e c 2 . (author). 20 refs, 4 figs
Current Direct Neutrino Mass Experiments
Directory of Open Access Journals (Sweden)
G. Drexlin
2013-01-01
Full Text Available In this contribution, we review the status and perspectives of direct neutrino mass experiments, which investigate the kinematics of β-decays of specific isotopes (3H, 187Re, 163Ho to derive model-independent information on the averaged electron (antineutrino mass. After discussing the kinematics of β-decay and the determination of the neutrino mass, we give a brief overview of past neutrino mass measurements (SN1987a-ToF studies, Mainz and Troitsk experiments for 3H, cryobolometers for 187Re. We then describe the Karlsruhe Tritium Neutrino (KATRIN experiment currently under construction at Karlsruhe Institute of Technology, which will use the MAC-E-Filter principle to push the sensitivity down to a value of 200 meV (90% C.L.. To do so, many technological challenges have to be solved related to source intensity and stability, as well as precision energy analysis and low background rate close to the kinematic endpoint of tritium β-decay at 18.6 keV. We then review new approaches such as the MARE, ECHO, and Project8 experiments, which offer the promise to perform an independent measurement of the neutrino mass in the sub-eV region. Altogether, the novel methods developed in direct neutrino mass experiments will provide vital information on the absolute mass scale of neutrinos.
Neutrino mass models and CP violation
International Nuclear Information System (INIS)
Joshipura, Anjan S.
2011-01-01
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.
Leptogenesis. Theory and neutrino masses
Energy Technology Data Exchange (ETDEWEB)
Buchmueller, W.
2012-12-15
After a brief discussion of baryon and lepton number nonconservation, we review the status of thermal leptogenesis with GUT scale neutrino masses, as well as low scale alternatives with keV neutrinos as dark matter and heavy neutrino masses within the reach of the LHC. Recent progress towards a full quantum mechanical description of leptogenesis is described with resonant leptogenesis as an application. Finally, cosmological B-L breaking after inflation is considered as origin of the hot early universe, generating entropy, baryon asymmetry and dark matter.
International Nuclear Information System (INIS)
Anon.
1988-01-01
The successes in capturing neutrinos from last year's supernova underlined the usefulness of large underground detectors for this sort of physics, and ambitious new projects are now in the pipeline. Meanwhile another approach to cosmic neutrino detection, carefully prepared during the past decade, has now taken its first experimental steps. DUMAND - Deep Underwater Muon and Neutrino Detector - aims to use the ocean as the active medium, tracking particles with arrays of photomultipliers picking up the tiny nanosecond flashes of blue Cherenkov light emitted by cosmic particles as they pass through seawater
Energy Technology Data Exchange (ETDEWEB)
Anon.
1988-06-15
The successes in capturing neutrinos from last year's supernova underlined the usefulness of large underground detectors for this sort of physics, and ambitious new projects are now in the pipeline. Meanwhile another approach to cosmic neutrino detection, carefully prepared during the past decade, has now taken its first experimental steps. DUMAND - Deep Underwater Muon and Neutrino Detector - aims to use the ocean as the active medium, tracking particles with arrays of photomultipliers picking up the tiny nanosecond flashes of blue Cherenkov light emitted by cosmic particles as they pass through seawater.
Froggatt-Nielsen hierarchy and the neutrino mass matrix
International Nuclear Information System (INIS)
Kamikado, H.; Takasugi, E.
2008-05-01
We study the neutrino mass matrix derived from the seesaw mechanism in which the neutrino Yukawa couplings and the heavy Majorana neutrino mass matrix are controlled by the Froggatt-Nielsen mechanism. In order to obtain the large neutrino mixings, two Froggatt-Nielsen fields are introduced with a complex vacuum expectation values. As a by-product, CP violation is systematically induced even if the order one couplings of FN fields are real. We show several predictions of this model, such as θ 13 , the Dirac CP phase, two Majorana CP phases, the effective mass of the neutrinoless double beta decay and the leptogenesis. The prediction of the branching ratio of μ→eγ is also given in SUSY model. (orig.)
Babu; Barr
2000-08-07
A generalization of the well-known Georgi-Jarlskog relation (m(&mgr;)/m(tau)) = 3(m(s)/m(b)) to neutrinos is found in the context of SO(10). This new relation is (m(nu(&mgr;))/m(nu(tau))) = 16(m(c)/m(t)), which is consistent with present data, assuming the Mikheyev-Smirnov-Wolfenstein solution to the solar neutrino problem.
International Nuclear Information System (INIS)
Babu, K. S.; Barr, S. M.
2000-01-01
A generalization of the well-known Georgi-Jarlskog relation (m μ /m τ ) =3(m s /m b ) to neutrinos is found in the context of SO(10) . This new relation is (m ν μ /m ν τ )=16(m c /m t ) , which is consistent with present data, assuming the Mikheyev-Smirnov-Wolfenstein solution to the solar neutrino problem. (c) 2000 The American Physical Society
Direct measurements of neutrino mass
International Nuclear Information System (INIS)
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 Β decay of 35 S and 63 Ni. Many other experiments are being reported and the situation is still unresolved. 56 refs., 1 fig., 3 tabs
Status of neutrino mass experiments
International Nuclear Information System (INIS)
Fackler, O.
1985-01-01
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 the author discuss electron antineutrino (hereafter referred to as neutrino) mass experiments. Section I begins with a discussion of astronomical and terrestrial observations which motivated these experiments. In Section II, the author quote limits from muon and tau mass determinations. These limits are more thoroughly discussed in other paper. The author continues by describing the four approaches used to measure the electron neutrino mass. In Section III, tritium beta decay mass determinations are reviewed. This section includes a general summary of previous experimental results, and discussion of the major ongoing experiments. Section IV offers concluding remarks
Status of neutrino mass experiments
International Nuclear Information System (INIS)
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
Neutrino masses and family symmetry
International Nuclear Information System (INIS)
Grinstein, B.; Preskill, J.; Wise, M.B.
1985-01-01
Neutrino masses in the 100 eV-1 MeV range are permitted if there is a spontaneously broken global family symmetry that allows the heavy neutrinos to decay by Goldstone boson emission with a cosmologically acceptable lifetime. The family symmetry may be either abelian or nonabelian; we present models illustrating both possibilities. If the family symmetry is nonabelian, then the decay tau -> μ + Goldstone boson or tau -> e + Goldstone may have an observable rate. (orig.)
The Mainz Neutrino Mass Experiment
Czech Academy of Sciences Publication Activity Database
Kraus, C.; Bornschein, L.; Bonn, J.; Bornschein, B.; Flatt, B.; Kovalík, Alojz; Müller, B.; Otten, EW; Schall, JP.; Thummler, T.; Weinheimer, C.
2005-01-01
Roč. 143, - (2005), s. 143 ISSN 0920-5632. [International Conference on Neutrino Physics and Astrophysics /21./. Paříž, 14.06.2004-19.06.2004] R&D Projects: GA MŠk 1P04LA213 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutrino mass * tritium beta decay Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.875, year: 2005
International Nuclear Information System (INIS)
Gil-Botella, I.
2011-01-01
The fundamental properties of neutrinos are reviewed in these lectures. The first part is focused on the basic characteristics of neutrinos in the Standard Model and how neutrinos are detected. Neutrino masses and oscillations are introduced and a summary of the most important experimental results on neutrino oscillations to date is provided. Then, present and future experimental proposals are discussed, including new precision reactor and accelerator experiments. Finally, different approaches for measuring the neutrino mass and the nature (Majorana or Dirac), of neutrinos are reviewed. The detection of neutrinos from supernovae explosions and the information that this measurement can provide are also summarized at the end. (author)
Neutrino mass textures with maximal CP violation
International Nuclear Information System (INIS)
Aizawa, Ichiro; Kitabayashi, Teruyuki; Yasue, Masaki
2005-01-01
We show three types of neutrino mass textures, which give maximal CP violation as well as maximal atmospheric neutrino mixing. These textures are described by six real mass parameters: one specified by two complex flavor neutrino masses and two constrained ones and the others specified by three complex flavor neutrino masses. In each texture, we calculate mixing angles and masses, which are consistent with observed data, as well as Majorana CP phases
Remarks on ''Neutrino masses and mixing angles in a predictive theory of fermion masses''
International Nuclear Information System (INIS)
Lavoura, L.; Silva, J.P.
1994-01-01
In the extension of the Dimopoulos-Hall-Raby model of the fermion mass matrices to the neutrino sector, there is an entry in the up-quark and neutrino Dirac mass matrices which can be assumed to arise from the Yukawa coupling of a 120, instead of a 10 or a 126, of SO(10). Although this assumption leads to an extra undetermined complex parameter in the model, the resulting lepton mixing matrix exhibits the remarkable feature that the ν τ does not mix with the other two neutrinos. Making a reasonable assumption about the extra parameter, we are able to fit the large-mixing-angle MSW solution of the solar-neutrino problem, and we obtain m ντ ∼10 eV, the right mass range to close the Universe. Other possibilities for explaining the solar-neutrino deficit are also discussed
Neutrino oscillation observables from mass matrix structure
International Nuclear Information System (INIS)
Winter, Walter
2008-01-01
We present a systematic procedure to establish a connection between complex neutrino mass matrix textures and experimental observables, including the Dirac CP phase. In addition, we illustrate how future experimental measurements affect the selection of textures in the (θ 13 ,δ CP )-plane. For the mixing angles, we use generic assumptions motivated by quark-lepton complementarity. We allow for any combination between U l and U ν , as well as we average over all present complex phases. We find that individual textures lead to very different distributions of the observables, such as to large or small leptonic CP violation. In addition, we find that the extended quark-lepton complementarity approach motivates future precision measurements of δ CP at the level of θ C ≅11 deg
Signatures of the neutrino mass hierarchy in supernova neutrinos
International Nuclear Information System (INIS)
Chiu, S.H.; Huang, Chu-Ching; Lai, Kwang-Chang
2015-01-01
The undetermined neutrino mass hierarchy may leave an observable imprint on the neutrino fluxes from a core-collapse supernova (SN). The interpretation of the observables, however, is subject to the uncertain SN models and the flavor conversion mechanism of neutrinos in a SN. We attempt to propose a qualitative interpretation of the expected neutrino events at terrestrial detectors, focusing on the accretion phase of the neutrino burst. The flavor conversions due to neutrino self-interaction, the MSW effect, and the Earth regeneration effect are incorporated in the calculation. It leads to several distinct scenarios that are identified by the neutrino mass hierarchies and the collective flavor transitions. Consequences resulting from the variation of incident angles and SN models are also discussed
Neutrino mass matrix and hierarchy
International Nuclear Information System (INIS)
Kaus, Peter; Meshkov, Sydney
2003-01-01
We build a model to describe neutrinos based on strict hierarchy, incorporating as much as possible, the latest known data, for Δsol and Δatm, and for the mixing angles determined from neutrino oscillation experiments, including that from KamLAND. Since the hierarchy assumption is a statement about mass ratios, it lets us obtain all three neutrino masses. We obtain a mass matrix, Mν and a mixing matrix, U, where both Mν and U are given in terms of powers of Λ, the analog of the Cabibbo angle λ in the Wolfenstein representation, and two parameters, ρ and κ, each of order one. The expansion parameter, Λ, is defined by Λ2 = m2/m3 = √(Δsol/Δatm) ≅ 0.16, and ρ expresses our ignorance of the lightest neutrino mass m1, (m1 ρΛ4m3), while κ scales s13 to the experimental upper limit, s13 = κΛ2 ≅ 0.16κ. These matrices are similar in structure to those for the quark and lepton families, but with Λ about 1.6 times larger than the λ for the quarks and charged leptons. The upper limit for the effective neutrino mass in double β-decay experiments is 4 x 10-3eV if s13 = 0 and 6 x 10-3eV if s13 is maximal. The model, which is fairly unique, given the hierarchy assumption and the data, is compared to supersymmetric extension and texture zero models of mass generation
Direct measurements of neutrino masses
Energy Technology Data Exchange (ETDEWEB)
Holzschuh, E [Zurich Univ. (Switzerland). Inst. fuer Physik
1996-11-01
The direct measurements have so far given no indication for a nonzero (positive) mass of any of the three known neutrinos. The experiments measuring the tau and the muon neutrino are good shape. The tritium experiments are in an unfortunate situation. It is unclear to me whether the problems are experimental or theoretical or a combination of both. The electronic final states distribution have been calculated, but the results have never been tested experimentally. The most important question to be answered is about the validity of the sudden approximation. (author) 9 figs., 2 tabs., 16 refs.
Neutrino Mass and Flavour Models
International Nuclear Information System (INIS)
King, Stephen F.
2010-01-01
We survey some of the recent promising developments in the search for the theory behind neutrino mass and tri-bimaximal mixing, and indeed all fermion masses and mixing. We focus in particular on models with discrete family symmetry and unification, and show how such models can also solve the SUSY flavour and CP problems. We also discuss the theoretical implications of the measurement of a non-zero reactor angle, as hinted at by recent experimental measurements.
Identifying the neutrino mass spectrum from a supernova neutrino burst
International Nuclear Information System (INIS)
Dighe, A.S.; Smirnov, A.Yu.
1999-12-01
We study the role that the future detection of the neutrino burst from a galactic supernova can play in the reconstruction of the neutrino mass spectrum. We consider all possible 3ν mass and flavor spectra which describe the solar and atmospheric neutrino data. For each of these spectra we find the observable effects of the supernova neutrino conversions both in the matter of the star and the earth. We show that studies of the electron neutrino and antineutrino spectra as well as observations of the neutral current effects from supernova will allow us (i) to identify the solar neutrino solution, (ii) to determine the type of mass hierarchy (normal or inverted) and (iii) to probe the mixing vertical bar U e3 vertical bar 2 to values as low as 10 -4 - 10 -3 . (author)
Introduction to models of neutrino masses and mixings
International Nuclear Information System (INIS)
Joshipura, Anjan S.
2004-01-01
This review contains an introduction to models of neutrino masses for non-experts. Topics discussed are i) different types of neutrino masses ii) structure of neutrino masses and mixing needed to understand neutrino oscillation results iii) mechanism to generate neutrino masses in gauge theories and iv) discussion of generic scenarios proposed to realize the required neutrino mass structures. (author)
Neutrino mass from M theory SO(10)
International Nuclear Information System (INIS)
Acharya, Bobby S.; Bożek, Krzysztof; Romão, Miguel Crispim; King, Stephen F.; Pongkitivanichkul, Chakrit
2016-01-01
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.
Neutrino mass from M theory SO(10)
Energy Technology Data Exchange (ETDEWEB)
Acharya, Bobby S. [Department of Physics, King’s College,WC2R 2LS, London (United Kingdom); International Centre for Theoretical Physics,I-34151 Trieste (Italy); Bożek, Krzysztof [Department of Physics, King’s College,WC2R 2LS, London (United Kingdom); Romão, Miguel Crispim; King, Stephen F. [School of Physics and Astronomy, University of Southampton,SO17 1BJ, Southampton (United Kingdom); Pongkitivanichkul, Chakrit [Department of Physics, King’s College,WC2R 2LS, London (United Kingdom)
2016-11-29
We study the origin of neutrino mass from SO(10) arising from M Theory compactified on a G{sub 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.
Radiative neutrino mass model with degenerate right-handed neutrinos
International Nuclear Information System (INIS)
Kashiwase, Shoichi; Suematsu, Daijiro
2016-01-01
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. (orig.)
Effects of neutrino oscillation on supernova neutrino. Inverted mass hierarchy
International Nuclear Information System (INIS)
Takahashi, Keitaro; Sato, Katsuhiko
2003-01-01
We study the effects of neutrino oscillation on supernova neutrinos in the case of the inverted mass hierarchy (m 3 1 2 ) as well as the normal mass hierarchy (m 1 2 3 ). Numerical analysis using realistic supernova and presupernova models allows us to investigate quantitatively the possibility to probe neutrino oscillation parameters. We show that information about the mass hierarchy can be obtained if θ 13 is rather large (sin 2 2θ 13 > 10 -3 ) and that θ 13 can be probed effectively by SuperKamiokande if the neutrino mass hierarchy is inverted. Errors due to the uncertainty in the original neutrino spectra and the Earth effect are also discussed. (author)
LHC and the origin of neutrino mass
International Nuclear Information System (INIS)
Senjanovic, Goran
2008-01-01
It is often said that neutrino mass is a window to a new physics beyond the standard model (SM). This is true if neutrinos are Majorana particles for the SM with Majorana neutrino mass is not a complete theory. The classical text-book test of neutrino Majorana mass, the neutrino-less double beta decay depends on the completion, and thus cannot probe neutrino mass. As pointed out already twenty five years ago, the colliders such as Tevatron or LHC offer a hope of probing directly the origin of neutrino (Majorana) mass through lepton number violating production of like sign lepton pairs. I make a case here for this in the context of all three types of seesaw mechanism.
International Nuclear Information System (INIS)
Mannheim, P.D.
1988-01-01
We derive the standard formalism of Mikheyev, Smirnov, and Wolfenstein for the oscillation of neutrinos in matter taking into account the Lorentz and second-quantized structure of the neutrino fields. We consider neutrinos with Dirac or Majorana masses
Neutrino oscillations and the seesaw origin of neutrino mass
Energy Technology Data Exchange (ETDEWEB)
Miranda, O.G., E-mail: omr@fis.cinvestav.mx [Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. Postal 14-740, 07000 Mexico, Distrito Federal (Mexico); Valle, J.W.F. [AHEP Group, Institut de Física Corpuscular – C.S.I.C./Universitat de València, Parc Cientific de Paterna, C/Catedratico José Beltrán, 2, E-46980 Paterna (València) (Spain)
2016-07-15
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.
Neutrino Masses and Mixings and Astrophysics
Fuller, George M.
1998-10-01
Here we discuss the implications of light neutrino masses and neutrino flavor/type mixing for dark matter, big bang nucleosynthesis, and models of heavy element nucleosynthesis in super novae. We will also argue the other way and discuss possible constraints on neutrino physics from these astrophysical considerations.
Neutrino masses in astrophysics and cosmology
International Nuclear Information System (INIS)
Raffelt, G.G.
1996-01-01
Astrophysical and cosmological arguments and observations give us the most restrictive constraints on neutrino masses, electromagnetic couplings, and other properties. Conversely, massive neutrinos would contribute to the cosmic dark-matter density and would play an important role for the formation of structure in the universe. Neutrino oscillations may well solve the solar neutrino problem, and can have a significant impact on supernova physics. (author) 14 figs., tabs., 33 refs
Neutrino masses in astrophysics and cosmology
Energy Technology Data Exchange (ETDEWEB)
Raffelt, G G [Max-Planck-Institut fuer Physik, Muenchen (Germany)
1996-11-01
Astrophysical and cosmological arguments and observations give us the most restrictive constraints on neutrino masses, electromagnetic couplings, and other properties. Conversely, massive neutrinos would contribute to the cosmic dark-matter density and would play an important role for the formation of structure in the universe. Neutrino oscillations may well solve the solar neutrino problem, and can have a significant impact on supernova physics. (author) 14 figs., tabs., 33 refs.
Neutrino Masses and Oscillations
CERN. Geneva. Audiovisual Unit; Treille, Daniel
2002-01-01
This course will not cover its subject in the customary way. The emphasis will be on the simple theoretical concepts (helicity, handedness, chirality, Majorana masses) which are obscure in most of the literature, and on the quantum mechanics of oscillations, that ALL books get wrong. Which, hopefully, will not deter me from discussing some of the most interesting results from the labs and from the cosmos.
The {mu} term and neutrino masses
Energy Technology Data Exchange (ETDEWEB)
Chen, Mu-Chun [California Univ., Irvine, CA (United States). Dept. of Physics and Astronomy; Ratz, Michael; Staudt, Christian [Technische Univ. Muenchen, Garching (Germany). Physik-Department; Vaudrevange, Patrick K.S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2012-06-15
The well-known Giudice-Masiero mechanism explains the presence of a {mu} term of the order of the gravitino mass, but does not explain why the holomorphic mass term is absent in the superpotential. We discuss anomaly-free discrete symmetries which are both compatible with SU(5) unification of matter and the Giudice-Masiero mechanism, i.e. forbid the {mu} term in the superpotential while allowing the necessary Kaehler potential term. We find that these are Z{sup R}{sub M} symmetries with the following properties: (i) M is a multiple of four; (ii) the Higgs bilinear H{sub u} H{sub d} transforms trivially; (iii) the superspace coordinate {theta} has charge M/4 and, accordingly, the superpotential has charge M/2; (iv) dimension five proton decay operators are automatically absent. All Z{sup R}{sub M} symmetries are anomaly-free due to a non-trivial transformation of a Green-Schwarz axion, and, as a consequence, a holomorphic {mu} term appears at the non-perturbative level. There is a unique symmetry that is consistent with the Weinberg operator while there is a class of Z{sup R}{sub M} symmetries which explain suppressed Dirac neutrino masses.
The μ term and neutrino masses
International Nuclear Information System (INIS)
Chen, Mu-Chun
2012-06-01
The well-known Giudice-Masiero mechanism explains the presence of a μ term of the order of the gravitino mass, but does not explain why the holomorphic mass term is absent in the superpotential. We discuss anomaly-free discrete symmetries which are both compatible with SU(5) unification of matter and the Giudice-Masiero mechanism, i.e. forbid the μ term in the superpotential while allowing the necessary Kaehler potential term. We find that these are Z R M symmetries with the following properties: (i) M is a multiple of four; (ii) the Higgs bilinear H u H d transforms trivially; (iii) the superspace coordinate θ has charge M/4 and, accordingly, the superpotential has charge M/2; (iv) dimension five proton decay operators are automatically absent. All Z R M symmetries are anomaly-free due to a non-trivial transformation of a Green-Schwarz axion, and, as a consequence, a holomorphic μ term appears at the non-perturbative level. There is a unique symmetry that is consistent with the Weinberg operator while there is a class of Z R M symmetries which explain suppressed Dirac neutrino masses.
Hernandez, P.
2016-01-01
This is the writeup of the lectures on neutrino physics delivered at various schools: TASI and Trieste in 2013 and the CERN-Latin American School in 2015. The topics discussed in this lecture include: general properties of neutrinos in the SM, the theory of neutrino masses and mixings (Dirac and Majorana), neutrino oscillations both in vacuum and in matter, as well as an overview of the experimental evidence for neutrino masses and of the prospects in neutrino oscillation physics. We also briefly review the relevance of neutri- nos in leptogenesis and in beyond-the-Standard-Model physics.
Probing the Absolute Mass Scale of Neutrinos
International Nuclear Information System (INIS)
Formaggio, Joseph A.
2011-01-01
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.
Identifying the neutrino mass hierarchy with supernova neutrinos
International Nuclear Information System (INIS)
Tomas, Ricard
2006-01-01
We review how a high-statistics observation of the neutrino signal from a future galactic core-collapse supernova (SN) may be used to discriminate between different neutrino mixing scenarios. We discuss two complementary methods that allow for the positive identification of the mass hierarchy without knowledge of the emitted neutrino fluxes, provided that the 13-mixing angle is large, sin 2 θ 13 -5 . These two approaches are the observation of modulations in the neutrino spectra by Earth matter effects or by the passage of shock waves through the SN envelope. If the value of the 13-mixing angle is unknown, using additionally the information encoded in the prompt neutronization ν e burst-a robust feature found in all modern SN simulations-can be sufficient to fix both the neutrino hierarchy and to decide whether θ 13 is 'small' or 'large'
Effects of neutrino oscillation on supernova neutrino: inverted mass hierarchy
International Nuclear Information System (INIS)
Takahashi, Keitaro; Sato, Katsuhiko
2003-01-01
We study the effects of neutrino oscillation on supernova neutrino in the case of the inverted mass hierarchy (m 3 1 2 ). This is an extended study of our previous study where all analyses are performed with normal mass hierarchy (m 1 2 3 ). Numerical analysis using a realistic supernova and presupernova model allow us to discuss quantitatively a possibility to probe neutrino oscillation parameters. We show that we can break partly the degeneracy of the solar neutrino problem (LMA or SMA) and probe the magnitude of θ 13 to some extent by the ratios of high-energy events and low-energy events at SuperKamiokande and SNO and the presence of the Earth effects. Further, if the magnitude of θ 13 is known roughly, we can identify the mass hierarchy
International Nuclear Information System (INIS)
Berstein, J.
1984-01-01
These lectures offer a self-contained review of the role of neutrinos in cosmology. The first part deals with the question 'What is a neutrino.' and describes in a historical context the theoretical ideas and experimental discoveries related to the different types of neutrinos and their properties. The basic differences between the Dirac neutrino and the Majorana neutrino are pointed out and the evidence for different neutrino 'flavours', neutrino mass, and neutrino oscillations is discussed. The second part summarizes current views on cosmology, particularly as they are affected by recent theoretical and experimental advances in high-energy particle physics. Finally, the close relationship between neutrino physics and cosmology is brought out in more detail, to show how cosmological constraints can limit the various theoretical possibilities for neutrinos and, more particularly, how increasing knowledge of neutrino properties can contribute to our understanding of the origin, history, and future of the Universe. The level is that of the beginning graduate student. (orig.)
JUNO. Determination of the neutrino mass hierarchy using reactor neutrinos
Energy Technology Data Exchange (ETDEWEB)
Wonsak, Bjoern [Hamburg University, Inst. Exp. Phys., Hamburg (Germany)
2015-07-01
The Jiangmen Underground Neutrino Observatory (JUNO) is a medium-baseline reactor neutrino experiment located in China. Its aim is to determine the neutrino mass hierarchy at more than 3 sigma significance after six years of data taking by using a 20kt liquid scintillator detector. To achieve this goal, an energy resolution of less than 3%/√(E) is necessary, creating strict requirements on the detector design and the liquid scintillator. Moreover, JUNO will be the only experiment in the near future able to measure the solar mixing parameters with a precision of better than 1%. This is at the same level as our current knowledge on flavour mixing in the quark sector, marking an important milestone of neutrino physics. In addition, supernova neutrinos, geo-neutrinos, sterile neutrinos as well as solar and atmospheric neutrinos can be studied. JUNO was approved in 2013 and the construction of the underground facility started early this year. In this talk the status of the experiment and its prospects is discussed.
Neutrino masses and beyond from supersymmetry
International Nuclear Information System (INIS)
Kong, O.C.W.
2004-01-01
A generic form of the supersymmetric SM naturally gives rise to the lepton number violating neutrino masses and mixings, without the need for extra superfields beyond the minimal spectrum. Hence, SUSY can be considered the origin of beyond SM properties of neutrinos. We have developed a formulation under which one can efficiently analyze the model. Various sources of neutrino masses are discussed. Such mass contributions come from lepton number and flavor violating couplings that also give rise to a rich phenomenology of the neutrinos and other leptons, also to be discussed. (author)
Mass of neutrino and particle physics
Yanagida, T
2003-01-01
We give a brief review on the seesaw mechanism in a grand unified theory which predicts small neutrino masses. In the seesaw mechanism the lepton-number conservation is broken and neutrinos have Majorana type masses. We also explain why the lepton-number nonconservation can be an origin of the baryon-number asymmetry in the present universe. (author)
The IBM neutrino-mass experiment
International Nuclear Information System (INIS)
Clark, G.J.; Frisch, M.A.; Chaudhari, P.; Bregman, M.F.
1985-01-01
IBM is undertaking an experiment to measure the electron anti-neutrino mass. A high precision measurement of the tritium Β-decay spectrum near the end point is used to infer the neutrino mass. Electron energies are measured using a large spherical retarding grid analyzer. We are placing particular emphasis on understanding the complications introduced by solid state effects in the source
The IBM neutrino-mass experiment
International Nuclear Information System (INIS)
Clark, G.J.; Frisch, M.A.; Chaudhari, P.; Bregman, M.F.
1985-01-01
IBM is undertaking an experiment to measure the electron anti-neutrino mass. A high precision measurement of the tritium β-decay spectrum near the end point is used to infer the neutrino mass. Electron energies are measured using a large spherical retarding grid analyzer. They are placing particular emphasis on understanding the complications introduced by solid state effects in the source
A neutrino mass-mixing sum rule from SO(10) and neutrinoless double beta decay
Energy Technology Data Exchange (ETDEWEB)
Buccella, F. [INFN, Sezione di Napoli,Complesso University Monte S. Angelo, I-80126 Napoli (Italy); Chianese, M. [INFN, Sezione di Napoli,Complesso University Monte S. Angelo, I-80126 Napoli (Italy); Dipartimento di Fisica Ettore Pancini, Università di Napoli Federico II,Complesso University Monte S. Angelo, I-80126 Napoli (Italy); Mangano, G. [INFN, Sezione di Napoli,Complesso University Monte S. Angelo, I-80126 Napoli (Italy); Miele, G.; Morisi, S.; Santorelli, P. [INFN, Sezione di Napoli,Complesso University Monte S. Angelo, I-80126 Napoli (Italy); Dipartimento di Fisica Ettore Pancini, Università di Napoli Federico II,Complesso University Monte S. Angelo, I-80126 Napoli (Italy)
2017-04-03
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{sub ee}〉, and on the neutrino mass scale. Remarkably a lower limit for the lightest neutrino mass is obtained (m{sub lightest}≳7.5×10{sup −4} eV, at 3 σ level).
Neutrino mass and mixing, and non-accelerator experiments
International Nuclear Information System (INIS)
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
The experimental status of neutrino masses and mixings
International Nuclear Information System (INIS)
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 priors for cosmology from random matrices
Long, Andrew J.; Raveri, Marco; Hu, Wayne; Dodelson, Scott
2018-02-01
Cosmological measurements of structure are placing increasingly strong constraints on the sum of the neutrino masses, Σ mν, through Bayesian inference. Because these constraints depend on the choice for the prior probability π (Σ mν), we argue that this prior should be motivated by fundamental physical principles rather than the ad hoc choices that are common in the literature. The first step in this direction is to specify the prior directly at the level of the neutrino mass matrix Mν, since this is the parameter appearing in the Lagrangian of the particle physics theory. Thus by specifying a probability distribution over Mν, and by including the known squared mass splittings, we predict a theoretical probability distribution over Σ mν that we interpret as a Bayesian prior probability π (Σ mν). Assuming a basis-invariant probability distribution on Mν, also known as the anarchy hypothesis, we find that π (Σ mν) peaks close to the smallest Σ mν allowed by the measured mass splittings, roughly 0.06 eV (0.1 eV) for normal (inverted) ordering, due to the phenomenon of eigenvalue repulsion in random matrices. We consider three models for neutrino mass generation: Dirac, Majorana, and Majorana via the seesaw mechanism; differences in the predicted priors π (Σ mν) allow for the possibility of having indications about the physical origin of neutrino masses once sufficient experimental sensitivity is achieved. We present fitting functions for π (Σ mν), which provide a simple means for applying these priors to cosmological constraints on the neutrino masses or marginalizing over their impact on other cosmological parameters.
Neutrino masses twenty-five years later
International Nuclear Information System (INIS)
Valle, J.W.F.
2003-01-01
The discovery of neutrino mass marks a turning point in elementary particle physics, with important implications for nuclear and astroparticle physics. Here I give a brief update, where I summarize the current status of three-neutrino oscillation parameters from current solar, atmospheric, reactor and accelerator neutrino data, discuss the case for sterile neutrinos and LSND, and also the importance of tritium and double beta decay experiments probing the absolute scale of neutrino mass. In this opinionated look at the present of neutrino physics, I keep an eye in the future, and a perspective of the past, taking the opportunity to highlight Joe Schechter's pioneering contribution, which I have had the fortune to share, as his PhD student back in the early eighties
Neutrino masses and mixing: evidence and implications
International Nuclear Information System (INIS)
Gonzalez-Garcia, M.C.; Nir, Yosef
2003-01-01
Measurements of various features of the fluxes of atmospheric and solar neutrinos have provided evidence for neutrino oscillations and therefore for neutrino masses and mixing. The authors review the phenomenology of neutrino oscillations in vacuum and in matter. They present the existing evidence from solar and atmospheric neutrinos as well as the results from laboratory searches, including the final status of the Liquid Scintillator Neutrino Detector (LSND) experiment. The theoretical inputs that are used to interpret the experimental results are described in terms of neutrino oscillations. The allowed ranges for the mass and mixing parameters are derived in two frameworks: First, each set of observations is analyzed separately in a two-neutrino framework; Second, the data from solar and atmospheric neutrinos are analyzed in a three-active-neutrino framework. The theoretical implications of these results are then discussed, including the existence of new physics, the estimate of the scale of this new physics, and the lessons for grand unified theories, for models of extra dimensions and singlet fermions in the bulk, and for flavor models
PINGU sensitivity to neutrino mass hierarchy
International Nuclear Information System (INIS)
Groß, Andreas
2014-01-01
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
Dirac Mass Dynamics in Multidimensional Nonlocal Parabolic Equations
Lorz, Alexander
2011-01-17
Nonlocal Lotka-Volterra models have the property that solutions concentrate as Dirac masses in the limit of small diffusion. Is it possible to describe the dynamics of the limiting concentration points and of the weights of the Dirac masses? What is the long time asymptotics of these Dirac masses? Can several Dirac masses coexist? We will explain how these questions relate to the so-called "constrained Hamilton-Jacobi equation" and how a form of canonical equation can be established. This equation has been established assuming smoothness. Here we build a framework where smooth solutions exist and thus the full theory can be developed rigorously. We also show that our form of canonical equation comes with a kind of Lyapunov functional. Numerical simulations show that the trajectories can exhibit unexpected dynamics well explained by this equation. Our motivation comes from population adaptive evolution a branch of mathematical ecology which models Darwinian evolution. © Taylor & Francis Group, LLC.
Neutrino mass hierarchy and matter effects
Smirnov, Alexei Yu.
2013-01-01
Matter effects modify the mixing and the effective masses of neutrinos in a way which depends on the neutrino mass hierarchy. Consequently, for normal and inverted hierarchies the oscillations and flavor conversion results are different. Sensitivity to the mass hierarchy appears whenever the matter effects on the 1-3 mixing and mass splitting become substantial. This happens in supernovae in wide energy range and in the matter of the Earth. The Earth density profile is a multi-layer medium wh...
Depletion of atmospheric muon-neutrino fluxes and structure of Majorana mass matrix
International Nuclear Information System (INIS)
Tanimoto, Morimitsu; Matsuda, Masahisa
1993-01-01
We study the structures of the Dirac and Majorana mass matrices which give rise to the large lepton mixing expected from the depleted atmospheric muonneutrino flux. In the case that the Majorana mass matrix has a hierarchy for generations, a certain kind of the neutrino Dirac mass matrix with the hierarchical structure leads to the large lepton mixing between the second generation and the third one. Our model-independent analyses serve the model-building of the mass matrices based on the quark-lepton unified theory. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Hung, P.Q.; Le, Trinh [Department of Physics, University of Virginia,Charlottesville, VA 22904-4714 (United States)
2015-09-01
We present a model of neutrino masses within the framework of the EW-ν{sub R} model in which the experimentally desired form of the PMNS matrix is obtained by applying an A{sub 4} symmetry to the Higgs singlet sector responsible for the neutrino Dirac mass matrix. This mechanism naturally avoids potential conflict with the LHC data which severely constrains the Higgs sector, in particular the Higgs doublets. Moreover, by making a simple ansa{sup ¨}tz we extract M{sub l}M{sub l}{sup †} for the charged lepton sector. A similar ansa{sup ¨}tz is proposed for the quark sector. The sources of masses for the neutrinos are entirely different from those for the charged leptons and for the quarks and this might explain why U{sub PMNS} is very different from V{sub CKM}.
Radiative stability of neutrino-mass textures
Indian Academy of Sciences (India)
physics pp. 647-650. Radiative stability of neutrino-mass textures. M K PARIDA ... A major challenge to particle physics at present is the theoretical understanding of ... A possible origin of two large neutrino mixings for /e -/μ and /μ -/г but small.
Neutrino masses and ordering via multimessenger astronomy
DEFF Research Database (Denmark)
Langæble, Kasper; Meroni, Aurora; Sannino, Francesco
2016-01-01
We define the theoretical framework and deduce the conditions under which multi-messenger 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...
Neutrino mass matrix: Inverted hierarchy and CP violation
International Nuclear Information System (INIS)
Frigerio, Michele; Smirnov, Alexei Yu.
2003-01-01
We reconstruct the neutrino mass matrix in the flavor basis, in the case of an inverted mass hierarchy (ordering), using all available experimental data on neutrino masses and oscillations. We analyze the dependence of the matrix elements m αβ on the CP violating Dirac δ and Majorana ρ and σ phases, for different values of the absolute mass scale. We find that the present data admit various structures of the mass matrix: (i) hierarchical structures with a set of small (zero) elements; (ii) structures with equalities among various groups of elements: e-row and/or μτ-block elements, diagonal and/or off-diagonal elements; (iii) 'democratic' structure. We find the values of phases for which these structures are realized. The mass matrix elements can anticorrelate with flavor: inverted partial or complete flavor alignment is possible. For various structures of the mass matrix we identify the possible underlying symmetry. We find that the mass matrix can be reconstructed completely only in particular cases, provided that the absolute scale of the mass is measured. Generally, the freedom related to the Majorana phase σ will not be removed, thus admitting various types of mass matrix
Hiding neutrino mass in modified gravity cosmologies
Energy Technology Data Exchange (ETDEWEB)
Bellomo, Nicola; Bellini, Emilio; Hu, Bin; Jimenez, Raul; Verde, Licia [ICC, University of Barcelona (UB-IEEC), Marti i Franques 1, 08028, Barcelona (Spain); Pena-Garay, Carlos, E-mail: nicola.bellomo@icc.ub.edu, E-mail: emilio.bellini@physics.ox.ac.uk, E-mail: binhu@icc.ub.edu, E-mail: raul.jimenez@icc.ub.edu, E-mail: penya@ific.uv.es, E-mail: liciaverde@icc.ub.edu [Instituto de Fisica Corpuscular, CSIC-UVEG, P.O. 22085, Valencia, 46071 (Spain)
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.
Supernova signatures of neutrino mass ordering
Scholberg, Kate
2018-01-01
A suite of detectors around the world is poised to measure the flavor-energy-time evolution of the ten-second burst of neutrinos from a core-collapse supernova occurring in the Milky Way or nearby. Next-generation detectors to be built in the next decade will have enhanced flavor sensitivity and statistics. Not only will the observation of this burst allow us to peer inside the dense matter of the extreme event and learn about the collapse processes and the birth of the remnant, but the neutrinos will bring information about neutrino properties themselves. This review surveys some of the physical signatures that the currently-unknown neutrino mass pattern will imprint on the observed neutrino events at Earth, emphasizing the most robust and least model-dependent signatures of mass ordering.
Neutrino mass hierarchy determination via atmospheric neutrinos with future detectors
International Nuclear Information System (INIS)
Gandhi, Raj; Ghoshal, Pomita; Goswami, Srubabati; Mehta, Poonam; Sankar, S Uma; Shalgar, Shashank
2008-01-01
The issue of determining the neutrino mass hierarchy is one of the outstanding questions in neutrino physics. We consider the potential of hierarchy determination using atmospheric neutrinos as the source in three different proposed future detectors: A large Iron Calorimeter detector, a megaton Water Cerenkov detector and a large-mass Liquid Argon detector. If the mixing angle θ 13 is about 10 deg. (close to CHOOZ upper bound), the hierarchy sensitivity is essentially determined by resonant matter effects. To maximize the potential of these effects in atmospheric neutrinos, charge discrimination capability in the detector is desirable. Hence, detectors with this capability have an advantage in hierarchy determination. We compare and contrast the performance of the above three detectors in this respect. We perform a realistic analysis of the above future detectors for atmospheric neutrinos and show that it is possible to achieve a significant hierarchy sensitivity if the detector characteristics are favourable. Note: The abstract has been modified from its original form to incorporate suggestions received during the conference. The poster is being submitted in its original form.
Neutrino mass and the origin of galactic magnetic fields
International Nuclear Information System (INIS)
Enqvist, K.; Semikoz, V.; Shukurov, A.; Sokoloff, D.
1993-01-01
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 4 He production at primordial nucleosynthesis, we can obtain a guaranteed upper limit on the strength of the relic magnetic field in the protogalaxy, B c approx-lt 4x10 -9 --3x10 -13 G, depending on the neutrino magnetic moment, if we adopt the MSW explanation of the GALLEX results. On the other hand, models of the dynamo in the Milky Way indicate that the seed magnetic field should be at least 10 -11 --10 -13 G at the protogalaxy scale L=100 kpc. These upper and lower limiting ranges are marginally consistent provided the electron neutrino mass is below 0.3 eV. The results apply to a relic magnetic field produced in the early Universe by any causal mechanism before the nucleosynthesis
Neutrino masses in the minimal gauged (B -L ) supersymmetry
Yan, Yu-Li; Feng, Tai-Fu; Yang, Jin-Lei; Zhang, Hai-Bin; Zhao, Shu-Min; Zhu, Rong-Fei
2018-03-01
We present the radiative corrections to neutrino masses in a minimal supersymmetric extension of the standard model with local U (1 )B -L symmetry. At tree level, three tiny active neutrinos and two nearly massless sterile neutrinos can be obtained through the seesaw mechanism. Considering the one-loop corrections to the neutrino masses, the numerical results indicate that two sterile neutrinos obtain KeV masses and the small active-sterile neutrino mixing angles. The lighter sterile neutrino is a very interesting dark matter candidate in cosmology. Meanwhile, the active neutrinos mixing angles and mass squared differences agree with present experimental data.
The Neutrino Mass Window for Baryogenesis
Buchmüller, Wilfried; Plümacher, Michael
2003-01-01
Interactions of heavy Majorana neutrinos in the thermal phase of the early universe may be the origin of the cosmological matter-antimatter asymmetry. This mechanism of baryogenesis implies stringent constraints on light and heavy Majorana neutrino masses. We derive an improved upper bound on the CP asymmetry in heavy neutrino decays which, together with the kinetic equations, yields an upper bound on all light neutrino masses of 0.1 eV. Lepton number changing processes at temperatures above the temperature T_B of baryogenesis can erase other, pre-existing contributions to the baryon asymmetry. We find that these washout processes become very efficient if the effective neutrino mass \\tilde{m}_1 is larger than m_* \\simeq 10^{-3} eV. All memory of the initial conditions is then erased. Hence, for neutrino masses in the range from (\\Delta m^2_sol)^{1/2} \\simeq 8*10^{-3} eV to (\\Delta m^2_atm)^{1/2} \\simeq 5*10^{-2} eV, which is suggested by neutrino oscillations, leptogenesis emerges as the unique source of the ...
Cosmological and astrophysical neutrino mass measurements
DEFF Research Database (Denmark)
Abazajian, K.N.; Calabrese, E.; Cooray, A.
2011-01-01
Cosmological and astrophysical measurements provide powerful constraints on neutrino masses complementary to those from accelerators and reactors. Here we provide a guide to these different probes, for each explaining its physical basis, underlying assumptions, current and future reach.......Cosmological and astrophysical measurements provide powerful constraints on neutrino masses complementary to those from accelerators and reactors. Here we provide a guide to these different probes, for each explaining its physical basis, underlying assumptions, current and future reach....
Probing Neutrino Mass Hierarchy with Supernova
International Nuclear Information System (INIS)
Chakraborty, Sovan
2013-01-01
The rise time of electron antineutrino lightcurve from a Galactic supernova (SN), observable at the IceCube Cherenkov detector, can provide signature of the neutrino mass hierarchy at “large” 1-3 leptonic mixing angle ϑ 13 . In the early accretion phase of the SN, the neutrino oscillations are nontrivial. Due to the matter suppression of collective effects at these early post bounce times, only the MSW resonances in the outer layers of the SN influence the neutrino flux. When the oscillations are taken into account, the signal in IceCube shows sufficiently fast rise time for the inverted mass hierarchy compared to the normal hierarchy. An investigation with an extensive set of stellar core-collapse simulations, provides both qualitative and quantitative robustness of these features. Thus opening another avenue to explore the neutrino mass hierarchy with the rise time of a supernova burst
Neutrino mass from laboratory: contribution of double beta decay to the neutrino mass matrix
International Nuclear Information System (INIS)
Klapdor-Kleingrothaus, H.V.
2001-01-01
Double beta decay is indispensable to solve the question of the neutrino mass matrix together with ν oscillation experiments. The most sensitive experiment - since eight years the HEIDELBERG-MOSCOW experiment in Gran-Sasso - already now, with the experimental limit of ν > < 0.26 eV practically excludes degenerate ν mass scenarios allowing neutrinos as hot dark matter in the universe for the smallangle MSW solution of the solar neutrino problem. It probes cosmological models including hot dark matter already now on the level of future satellite experiments MAP and PLANCK. It further probes many topics of beyond SM physics at the TeV scale. Future experiments should give access to the multi-TeV range and complement on many ways the search for new physics at future colliders like LHC and NLC. For neutrino physics some of them (GENIUS) will allow to test almost all neutrino mass scenarios allowed by the present neutrino oscillation experiments
Leptoquarks: Neutrino masses and related accelerator signals
International Nuclear Information System (INIS)
Aristizabal Sierra, D.; Hirsch, M.; Kovalenko, S. G.
2008-01-01
Leptoquark-Higgs interactions induce mixing between leptoquark (LQ) states with different chiralities once the electroweak symmetry is broken. In such LQ models Majorana neutrino masses are generated at 1-loop order. Here we calculate the neutrino mass matrix and explore the constraints on the parameter space enforced by the assumption that LQ-loops explain current neutrino oscillation data. LQs will be produced at the CERN LHC, if their masses are at or below the TeV scale. Since the fermionic decays of LQs are governed by the same Yukawa couplings, which are responsible for the nontrivial neutrino mass matrix, several decay branching ratios of LQ states can be predicted from measured neutrino data. Especially interesting is that large lepton flavor violating rates in muon and tau final states are expected. In addition, the model predicts that, if kinematically possible, heavier LQs decay into lighter ones plus either a standard model Higgs boson or a Z 0 /W ± gauge boson. Thus, experiments at the LHC might be able to exclude the LQ mechanism as an explanation of neutrino data.
Neutrino masses in flipped SU(5)
Energy Technology Data Exchange (ETDEWEB)
Abel, S.A. (Bristol Univ. (UK). H.H. Wills Physics Lab.)
1990-01-04
It is demonstrated that the, recently proposed, SU(5)xU(1) unification scheme is one of only a small number of the current candidates that allows, in its parameter space, the possibility of heavy neutrinos. This is due to the fact that the usual GIM suppression mechanism does not operate, leading to fast decays of heavy tau neutrinos of the form {nu}{yields}{nu}{gamma}, with an estimated lifetime of O(1 yr) for a tau neutrino mass of 1 MeV. Using well known cosmological arguments, based on the observed 3 K background radiation, the mass of the electron neutrino is constrained to be either greater than O(1 eV), or less than the usual limit of O(10{sup -2} eV). (orig.).
Determining the neutrino mass hierarchy with cosmology
International Nuclear Information System (INIS)
De Bernardis, Francesco; Kitching, Thomas D.; Heavens, Alan; Melchiorri, Alessandro
2009-01-01
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. 1σ, and the sum of masses by 2.3σ. 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.
EFFECTS OF THE NEUTRINO MASS SPLITTING ON THE NONLINEAR MATTER POWER SPECTRUM
International Nuclear Information System (INIS)
Wagner, Christian; Verde, Licia; Jimenez, Raul
2012-01-01
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-β decay experiments, this opens up the possibility of using the sky to determine if neutrinos are Majorana or Dirac fermions.
Comments on reconstruction and origins of the neutrino mass spectrum
International Nuclear Information System (INIS)
Smirnov, A.Yu.
2000-01-01
There are two main issues in the present day neutrino physics: (i) Reconstruction of the neutrino mass (and flavor) spectrum and (ii) Identification of origin of the neutrino mass and mixing, or in other terms, implications of the neutrino data for the fundamental theory. Present status and perspectives of the reconstruction are summarized. We comment on the see-saw and the 'bulk-brane' mechanisms of neutrino mass generation
A model for Simpson's 17 keV neutrino
International Nuclear Information System (INIS)
Rajpoot, S.
1992-01-01
Recent studies of β-decay spectra seem to confirm Simpson's earlier findings that the electron neutrinos contain a small (1%) admixture of a 17 keV Dirac neutrino. In this paper an unconventional model with SU(2) L x SU(2) R x U(1) B-1 gauge interactions is presented in which all neutrinos are Dirac particles. Electron and muon neutrinos acquire seesaw Dirac masses of order 10 -3 eV for the MSW solution for the solar neutrino problem. The τ neutrino is identified as Simpson's 17 keV neutrino. Constraints coming from cosmology and particle physics are shown to be satisfied
Baryon asymmetry via leptogenesis in a neutrino mass model with complex scaling
International Nuclear Information System (INIS)
Samanta, Rome; Ghosal, Ambar; Chakraborty, Mainak; Roy, Probir
2017-01-01
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 M ν , derived with a type-1 seesaw from a Dirac mass matrix m D and a heavy singlet neutrino Majorana mass matrix M R . One of its important features, highlighted here, is that there is a common source of the origin of a nonzero θ 13 and the CP violating lepton asymmetry through the imaginary part of m D . 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 M R . The leptonic CP asymmetry parameter ε α 1 mm with lepton flavor α, originating from the decays of the lightest of the heavy neutrinos N 1 (of mass M 1 ) at a temperature T ∼ M 1 , is what matters here with the lepton asymmetries, originating from the decays of N 2,3 , 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) M 1 < 10 9 GeV, (2) 10 9 GeV < M 1 < 10 12 GeV and (3) M 1 > 10 12 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 θ 13 playing a crucial role. However, the other possibility of an inverted mass ordering for the same mass regime, though disfavored, cannot be excluded. A
Baryon asymmetry via leptogenesis in a neutrino mass model with complex scaling
Energy Technology Data Exchange (ETDEWEB)
Samanta, Rome; Ghosal, Ambar [Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Kolkata 700064 (India); Chakraborty, Mainak [Centre of Excellence in Theoretical and Mathematical Sciences, SOA University, Khandagiri Square, Bhubaneswar 751030 (India); Roy, Probir, E-mail: rome.samanta@saha.ac.in, E-mail: mainak.chakraborty2@gmail.com, E-mail: probirrana@gmail.com, E-mail: ambar.ghosal@saha.ac.in [Center for Astroparticle Physics and Space Science, Bose Institute, Kolkata 700091 (India)
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 M {sub ν}, derived with a type-1 seesaw from a Dirac mass matrix m {sub D} and a heavy singlet neutrino Majorana mass matrix M {sub R} . One of its important features, highlighted here, is that there is a common source of the origin of a nonzero θ{sub 13} and the CP violating lepton asymmetry through the imaginary part of m {sub D} . 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 M {sub R} . The leptonic CP asymmetry parameter ε{sup α}{sub 1} mm with lepton flavor α, originating from the decays of the lightest of the heavy neutrinos N {sub 1} (of mass M {sub 1}) at a temperature T ∼ M {sub 1}, is what matters here with the lepton asymmetries, originating from the decays of N {sub 2,3}, 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) M {sub 1} < 10{sup 9} GeV, (2) 10{sup 9} GeV < M {sub 1} < 10{sup 12} GeV and (3) M {sub 1} > 10{sup 12} 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 θ{sub 13} playing a crucial role. However, the other
General property of neutrino mass matrix and CP-violation
International Nuclear Information System (INIS)
Aizawa, Ichiro; Yasue, Masaki
2005-01-01
It is found that the atmospheric neutrino mixing angle of θ atm is determined to be tanθ atm =Im(B)/Im(C) for B=M ν e ν μ and C=M ν e ν τ , where M ij is the ij element of M ν - bar M ν with M ν as a complex symmetric neutrino mass matrix in the (ν e , ν μ , ν τ )-basis. Another mixing angle, θ 13 , defined as U e3 =sinθ 13 e -iδ is subject to the condition: tan2θ 13 ∝|sinθ atm B+cosθ atm C| and the CP-violating Dirac phase of δ is identical to the phase of sinθ atm B*+cosθ atm C*. The smallest value of |sinθ 13 | is achieved at tanθ atm =-Re(C)/Re(B) that yields the maximal CP-violation and that implies C=-κB* for the maximal atmospheric neutrino mixing of tanθ atm =κ=+/-1. The generic smallness of |sinθ 13 | can be ascribed to the tiny violation of the electron number conservation
Neutrino mass and mixing – status
Indian Academy of Sciences (India)
be specific, a Majorana mass term for neutrinos, together with the mass term for charged leptons: LM = −. 1 .... hierarchy, respectively (see refs [5,6] for details and references). Parameter ... In figure 3 we show the region in the sin2 θ13–δ plane indicated by T2K ..... and 40 m and the precise rate measurement from Bugey4.
Leptoquarks and neutrino masses at the LHC
Energy Technology Data Exchange (ETDEWEB)
Fileviez Perez, Pavel [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)], E-mail: fileviez@physics.wisc.edu; Han Tao [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Li Tong [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Department of Physics, Nankai University, Tianjin 300071 (China); Center for High Energy Physics, Peking University, Beijing 100871 (China); Ramsey-Musolf, Michael J. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States)
2009-09-21
The properties of light leptoquarks predicted in the context of a simple grand unified theory and their observability at the LHC are investigated. The SU(5) symmetry of the theory implies that the leptoquark couplings to matter are related to the neutrino mass matrix. We study the resulting connection between neutrino masses and mixing parameters and the leptoquark decays, and show that different light neutrino hierarchies imply distinctive leptoquark decay signatures. We also discuss low-energy constraints implied by searches for charged lepton flavour violation, studies of meson decays, and electroweak precision data. We perform a detailed parton-level study of the leptoquark signals and the Standard Model backgrounds at the LHC. With the clean final states containing a di-lepton plus two jets, the QCD production of the leptoquark pair can be observed for a leptoquark mass of one TeV and beyond. By examining the lepton flavor structure of the observed events, one could further test the model predictions related to the neutrino mass spectrum. In particular, b-flavor tagging will be useful in distinguishing the neutrino mass pattern and possibly probing an unknown Majorana phase in the Inverted Hierarchy or the Quasi-Degenerate scenario. Electroweak associated production of the leptoquark doublet can also be useful in identifying the quantum numbers of the leptoquarks and distinguishing between the neutrino mass spectra, even though the corresponding event rates are smaller than for QCD production. We find that with only the clean channel of {mu}+E/{sub T}+jets, one could expect an observable signal for a leptoquark masses of about 600 GeV or higher.
Leptoquarks and neutrino masses at the LHC
International Nuclear Information System (INIS)
Fileviez Perez, Pavel; Han Tao; Li Tong; Ramsey-Musolf, Michael J.
2009-01-01
The properties of light leptoquarks predicted in the context of a simple grand unified theory and their observability at the LHC are investigated. The SU(5) symmetry of the theory implies that the leptoquark couplings to matter are related to the neutrino mass matrix. We study the resulting connection between neutrino masses and mixing parameters and the leptoquark decays, and show that different light neutrino hierarchies imply distinctive leptoquark decay signatures. We also discuss low-energy constraints implied by searches for charged lepton flavour violation, studies of meson decays, and electroweak precision data. We perform a detailed parton-level study of the leptoquark signals and the Standard Model backgrounds at the LHC. With the clean final states containing a di-lepton plus two jets, the QCD production of the leptoquark pair can be observed for a leptoquark mass of one TeV and beyond. By examining the lepton flavor structure of the observed events, one could further test the model predictions related to the neutrino mass spectrum. In particular, b-flavor tagging will be useful in distinguishing the neutrino mass pattern and possibly probing an unknown Majorana phase in the Inverted Hierarchy or the Quasi-Degenerate scenario. Electroweak associated production of the leptoquark doublet can also be useful in identifying the quantum numbers of the leptoquarks and distinguishing between the neutrino mass spectra, even though the corresponding event rates are smaller than for QCD production. We find that with only the clean channel of μ+E/ T +jets, one could expect an observable signal for a leptoquark masses of about 600 GeV or higher.
Experiment for a precision neutrino mass measurement
International Nuclear Information System (INIS)
Fackler, O.; Mugge, M.; Sticker, H.; Woerner, R.
1984-04-01
We describe an experiment which is designed to determine the electron neutrino mass to better than 2 eV. Key features of the experiment are a high activity frozen tritium source and a high resolution electrostatic spectrometer designed to make a careful measurement of the tritium beta decay end point spectrum. The goal is to determine the neutrino mass to better than 1 eV statistically in a four day run. A series of these runs will allow study of potential systematics. The construction phase is nearly complete and preliminary data will be taken in late spring
Atmospheric neutrino oscillations, θ13 and neutrino mass hierarchy
International Nuclear Information System (INIS)
Bernabeu, J.; Palomares-Ruiz, Sergio; Petcov, S.T.
2003-01-01
We derive predictions for the Nadir angle (θ n ) dependence of the ratio N μ /N e of the rates of the μ-like and e-like multi-GeV events measured in water-Cerenkov detectors in the case of 3-neutrino oscillations of the atmospheric ν e (ν-bar e ) and ν μ (ν-bar μ ), driven by one neutrino mass squared difference, vertical bar Δm 2 31 vertical bar ∼(2.5-3.0)x10 -3 eV 2 >> Δm 2 21 . This ratio is particularly sensitive to the Earth matter effects in the atmospheric neutrino oscillations, and thus to the values of sin 2 θ 13 and sin 2 θ 23 , θ 13 and θ 23 being the neutrino mixing angle limited by CHOOZ and Palo Verde experiments and that responsible for the dominant atmospheric ν μ →ν τ (ν-bar μ →ν-bar τ ) oscillations. It is also sensitive to the type of neutrino mass spectrum which can be with normal (Δm 2 31 >0) or with inverted (Δm 2 31 2 θ 13 > or approx. 0.01, sin 2 θ 23 > or approx. 0.5 and at cosθ n > or approx. 0.4, the Earth matter effects modify substantially the θ n -dependence of the ratio N μ /N e and in a way which cannot be reproduced with sin 2 θ 13 =0 and a different value of sin 2 θ 23 . For normal hierarchy the effects can be as large as ∼25% for cosθ n ∼(0.5-0.8), can reach ∼35% in the Earth core bin cosθ n ∼(0.84-1.0), and might be observable. They are typically by ∼10% smaller in the inverted hierarchy case. An observation of the Earth matter effects in the Nadir angle distribution of the ratio N μ /N e would clearly indicate that sin 2 θ 13 > or approx. 0.01 and sin 2 θ 23 > or approx. 0.50
The mass-hierarchy puzzle and the 17-keV neutrino in the context of a universal seesaw model
International Nuclear Information System (INIS)
Papageorgiu, E.; Ranfone, S.
1991-06-01
In the light of renewed evidence for the existence of a 17 keV neutrino, we study the possible mass patterns for the charged and the neutral leptons, in the context of a generalized ''seesaw''-type of model, which implements a horizontal U(1) A Peccei-Quinn symmetry. Under some general assumptions concerning the structure of the mass matrix we find that the mass hierarchy between the first two generations of charged leptons and the third one is explained in terms of the natural scales of the model. At the same time, with the additional assumption of the proportionality of Majorana- and Dirac-type couplings, the spectrum of the neutral leptons contains two very light Majorana neutrinos, such as required by the Mikheyev-Smirnov-Wolfenstein interpretation of the solar neutrino deficit, and the 17 keV ''Simpson'' neutrino. A cosmologically consistent decay mode of this neutrino is into a ν e and the axion. (author)
Constraining the lightest neutrino mass and mee from general ...
Indian Academy of Sciences (India)
surements. For example, neutrino oscillation experiments provide no clue regarding the absolute neutrino mass scale and the related issue of the neutrino mass hierarchy. Another important issue which needs to be taken note of is regarding the rather small neu- trino masses as compared to their charged counterparts.
Supernova constraints on neutrino mass and mixing
Indian Academy of Sciences (India)
the Chandrasekhar limiting mass the pressure of the relativistic electron gas alone can ... and facilitates electron capture by nuclei and free protons leading to .... the neutrino luminosity in units of 10 ¾ ergs/sec, Т and Ф are the neutron and proton ... would be changed to М . One can make a rough estimate of the increase in ...
Models of neutrino masses and baryogenesis
Indian Academy of Sciences (India)
Majorana masses of the neutrino implies lepton number violation and is intimately related to the lepton asymmetry of the universe, which gets related to the baryon asymmetry of the universe in the presence of the sphalerons during the electroweak phase transition. Assuming that the baryon asymmetry of the universe is ...
Neutrino Masses from Neutral Top Partners
Batell, Brian
2015-01-01
We present theories of `Natural Neutrinos' in which neutral fermionic top partner fields are simultaneously the right-handed neutrinos (RHN), linking seemingly disparate aspects of the Standard Model structure: a) The RHN top partners are responsible for the observed small neutrino masses, b) They help ameliorate the tuning in the weak scale and address the little hierarchy problem, and c) The factor of $3$ arising from $N_c$ in the top-loop Higgs mass corrections is countered by a factor $3$ from the number of vector-like generations of RHN. The RHN top partners may arise in pseudo-Nambu-Goldstone-Boson (pNGB) Higgs models such as the Twin Higgs, as well as more general Composite, Little, and Orbifold Higgs scenarios, and three simple example models are presented. This framework firmly predicts a TeV-scale seesaw, as the RHN masses are bounded to be below the TeV scale by naturalness. The generation of light neutrino masses relies on a collective breaking of lepton number, allowing for comparatively large ne...
CLFV and the origin of neutrino masses
Hambye, Thomas
2014-03-01
The neutrino oscillations constitute the unique absolute guarantee we have at the moment that charged lepton flavor violation (CLFV) processes do exist. Even if the associated rates are in general expected very suppressed, it turns out that this is not always necessarily the case. In the framework of the three basic seesaw models, we review the possibilities of having observable rates. Each seesaw case presenting a quite different CLFV pattern, we show how these observable rates could allow us to distinguish these various possible neutrino mass origins.
Models of neutrino mass and mixing
International Nuclear Information System (INIS)
Ma, Ernest
2000-01-01
There are two basic theoretical approaches to obtaining neutrino mass and mixing. In the minimalist approach, one adds just enough new stuff to the Minimal Standard Model to get m ν ≠0 and U αi ≠1. In the holistic approach, one uses a general framework or principle to enlarge the Minimal Standard Model such that, among other things, m ν ≠0 and U αi ≠1. In both cases, there are important side effects besides neutrino oscillations. I discuss a number of examples, including the possibility of leptogenesis from R parity nonconservation in supersymmetry
CLFV and the origin of neutrino masses
International Nuclear Information System (INIS)
Hambye, Thomas
2014-01-01
The neutrino oscillations constitute the unique absolute guarantee we have at the moment that charged lepton flavor violation (CLFV) processes do exist. Even if the associated rates are in general expected very suppressed, it turns out that this is not always necessarily the case. In the framework of the three basic seesaw models, we review the possibilities of having observable rates. Each seesaw case presenting a quite different CLFV pattern, we show how these observable rates could allow us to distinguish these various possible neutrino mass origins
Right-handed neutrinos at CERN LHC and the mechanism of neutrino mass generation
International Nuclear Information System (INIS)
Kersten, Joern; Smirnov, Alexei Yu.
2007-01-01
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 -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
Noncommutativity into Dirac Equation with mass dependent on the position
International Nuclear Information System (INIS)
Bastos, Samuel Batista; Almeida, Carlos Alberto Santos; Nunes, Luciana Angelica da Silva
2013-01-01
Full text: In recent years, there is growing interest in the study of theories in non-commutative spaces. Non-commutative fields theories are related with compactifications of M theory, string theory and the quantum Hall effect. Moreover, the role of the non-commutativity of theories of a particle finds large applications when analyzed in scenarios of quantum mechanics and relativistic quantum mechanics. In these contexts investigations on the Schrodinger and Dirac equations with mass depending on the position (MDP) has attracted much attention in the literature. Systems endowed with MDP models are useful for the study of many physical problems. In particular, they are used to study the energy density in problems of many bodies, determining the electronic properties of semiconductor heterostructures and also to describe the properties of heterojunctions and quantum dots. In particular, the investigation of relativistic effects it is important for systems containing heavy atoms or doping by heavy ions. For these types of materials, the study of the properties of the Dirac equation, in the case where the mass becomes variable is of great interest. In this paper, we seek for the non-relativistic limit of the Dirac Hamiltonian in the context of a theory of effective mass, through a Foldy-Wouthuysen transformation. We analyse the Dirac equation with mass dependent on the position, in a smooth step shape mass distribution, in non-commutative space (NC). This potential type kink was recently discussed by several authors in the commutative context and now we present our results in the non-commutative context. (author)
Double beta decay and neutrino mass models
Energy Technology Data Exchange (ETDEWEB)
Helo, J.C. [Universidad Técnica Federico Santa María, Centro-Científico-Tecnológico de Valparaíso, Casilla 110-V, Valparaíso (Chile); Hirsch, M. [AHEP Group, Instituto de Física Corpuscular - C.S.I.C./Universitat de València, Edificio de Institutos de Paterna, Apartado 22085, E-46071 València (Spain); Ota, T. [Department of Physics, Saitama University, Shimo-Okubo 255, 338-8570 Saitama-Sakura (Japan); Santos, F.A. Pereira dos [Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro,Rua Marquês de São Vicente 225, 22451-900 Gávea, Rio de Janeiro (Brazil)
2015-05-19
Neutrinoless double beta decay allows to constrain lepton number violating extensions of the standard model. If neutrinos are Majorana particles, the mass mechanism will always contribute to the decay rate, however, it is not a priori guaranteed to be the dominant contribution in all models. Here, we discuss whether the mass mechanism dominates or not from the theory point of view. We classify all possible (scalar-mediated) short-range contributions to the decay rate according to the loop level, at which the corresponding models will generate Majorana neutrino masses, and discuss the expected relative size of the different contributions to the decay rate in each class. Our discussion is general for models based on the SM group but does not cover models with an extended gauge. We also work out the phenomenology of one concrete 2-loop model in which both, mass mechanism and short-range diagram, might lead to competitive contributions, in some detail.
Neutrino mass constraints from joint cosmological probes.
Kwan, Juliana
2018-01-01
One of the most promising avenues to come from precision cosmology is the measurement of the sum of neutrino masses in the next 5-10 years. Ongoing imaging surveys, such as the Dark Energy Survey and the Hyper Suprime Cam survey, will cover a substantial volume of the sky and when combined with existing spectroscopic data, are expected to deliver a definitive measurement in the near future. But it is important that the accuracy of theoretical predictions matches the precision of the observational data so that the neutrino mass signal can be properly detected without systematic error. To this end, we have run a suite of high precision, large volume cosmological N-body simulations containing massive neutrinos to quantify their effect on probes of large scale structure such as weak lensing and galaxy clustering. In this talk, I will describe the analytical tools that we have developed to extract the neutrino mass that are capable of fully utilizing the non-linear regime of structure formation. These include predictions for the bias in the clustering of dark matter halos (one of the fundamental ingredients of the halo model) with an error of only a few percent.
Neutrino mass and mixing in the seesaw playground
International Nuclear Information System (INIS)
King, Stephen F.
2016-01-01
We discuss neutrino mass and mixing in the framework of the classic seesaw mechanism, involving right-handed neutrinos with large Majorana masses, which provides an appealing way to understand the smallness of neutrino masses. However, with many input parameters, the seesaw mechanism is in general not predictive. We focus on natural implementations of the seesaw mechanism, in which large cancellations do not occur, where one of the right-handed neutrinos is dominantly responsible for the atmospheric neutrino mass, while a second right-handed neutrino accounts for the solar neutrino mass, leading to an effective two right-handed neutrino model. We discuss recent attempts to predict lepton mixing and CP violation within such natural frameworks, focusing on the Littlest Seesaw and its distinctive predictions.
The νMSM, dark matter and neutrino masses
International Nuclear Information System (INIS)
Asaka, Takehiko; Blanchet, Steve; Shaposhnikov, Mikhail
2005-01-01
We investigate an extension of the Minimal Standard Model by right-handed neutrinos (the νMSM) to incorporate neutrino masses consistent with oscillation experiments. Within this theory, the only candidates for dark matter particles are sterile right-handed neutrinos with masses of a few keV. Requiring that these neutrinos explain entirely the (warm) dark matter, we find that their number is at least three. We show that, in the minimal choice of three sterile neutrinos, the mass of the lightest active neutrino is smaller than O(10 -5 ) eV, which excludes the degenerate mass spectra of three active neutrinos and fixes the absolute mass scale of the other two active neutrinos
Double beta decays and neutrino masses
International Nuclear Information System (INIS)
Ejiri, Hiro
2006-01-01
Neutrino-less double beta decays(0νββ) are of great interest for studying the Majorana nature of ν's and the absolute ν-mass scale. The present report is a brief review of the 0νββ studies with emphasis on future experiments with the mass sensitivity of an order of 25∼100 meV and on experimental probes for investigating 0νββ nuclear matrix elements
Lai, Kwang-Chang; Lee, Fei-Fan; Lee, Feng-Shiuh; Lin, Guey-Lin; Liu, Tsung-Che; Yang, Yi
2016-01-01
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, $\
Neutrino mass textures from F-theory
Antoniadis, I
2013-01-01
Experimental data on the neutrino mixing and masses strongly suggest an underlying approximate symmetry of the relevant Yukawa superpotential terms. Intensive phenomenological explorations during the last decade indicate that permutation symmetries such as S_4, A_4 and their subgroups, under certain assumptions and vacuum alignments, predict neutrino mass textures compatible with such data. Motivated by these findings, in the present work we analyse the neutrino properties in F-theory GUT models derived in the framework of the maximal underlying E_8 symmetry in the elliptic fibration. More specifically, we consider local F-SU(5) GUT models and study in detail spectral cover geometries with monodromies associated to the finite symmetries S_4, A_4 and their transitive subgroups, including the dihedral group D_4 and Z_2 X Z_2. We discuss various issues that emerge in the implementation of S_4, A_4 neutrino models in the F-theory context and suggest how these can be resolved. Realistic models are presented for th...
International Nuclear Information System (INIS)
Arkani-Hamed, Nima; Hall, Lawrence; Murayama, Hitoshi; Smith, David; Weiner, Neal
2000-01-01
Theories in which neutrino masses are generated by a conventional see-saw mechanism generically yield masses which are O(v 2 ) in units where M Pl = 1, which is naively too small to explain the results from SuperKamiokande. In supersymmetric theories with gravity mediated supersymmetry breaking, the fundamental small parameter is not v/M Pl , but m I /M Pl , where m I is the scale of supersymmetry breaking in the hidden sector. We note that m I 3 /M Pl 2 is only slightly too large to explain SuperKamiokande, and present two models that achieve neutrino masses at this order in m I , one of which has an additional suppression λ τ 2 , while the other has additional suppression arising from a loop factor. The latter model shares a great deal of phenomenology with a class of models previously explored, including the possibility of viable sneutrino dark matter
CERN. Geneva
2004-01-01
The Standard Model predicts that the neutrinos are massless and do not mix. Generic extensions of the Standard Model predict that neutrinos are massive (but, very likely, much lighter than the charged fermions). Therefore, the search for neutrino masses and mixing tests the Standard Model and probes new phasics. Measurements of various features of the fluxes of atmospheric, solar and, more recently, reactor neutrinos have provided evidence for neutrino oscillations and therefore for neutrino masses and mixing. These results have significant theoretical implications: new physics exists, and its scale can be estimated. There are interesting lessons for grand unified theories and for models of extra dimensions. The measured neutrino flavor parameters pose a challenge to flavor models.
Neutrino Mass Matrix Textures: A Data-driven Approach
Bertuzzo, E; Machado, P A N
2013-01-01
We analyze the neutrino mass matrix entries and their correlations in a probabilistic fashion, constructing probability distribution functions using the latest results from neutrino oscillation fits. Two cases are considered: the standard three neutrino scenario as well as the inclusion of a new sterile neutrino that potentially explains the reactor and gallium anomalies. We discuss the current limits and future perspectives on the mass matrix elements that can be useful for model building.
Neutrino mass spectrum with υμ → υs oscillations of atmospheric neutrinos
International Nuclear Information System (INIS)
Liu, Q.Y.; Smirnov, A.Yu.
1998-02-01
We consider the ''standard'' spectrum of the active neutrinos (characterized by strong mass hierarchy and small mixing) with additional sterile, υ s . The sterile neutrino mixes strongly with the muon neutrino, so that υ μ ↔ υ s oscillations solve the atmospheric neutrino problem. We show that the parametric enhancement of the υ μ ↔ υ s oscillations occurs for the high energy atmospheric neutrinos which cross the core of the Earth. This can be relevant for the anomaly observed by the MACRO experiment. Solar neutrinos are converted both to υ μ and υ s . The heaviest neutrino (approx. υ τ ) may compose the hot dark matter of the Universe. Phenomenology of this scenario is elaborated and crucial experimental signatures are identified. We also discuss properties of the underlying neutrino mass matrix. (author)
Neutrino masses and mixings: Big Bang and Supernova nucleosynthesis and neutrino dark matter
International Nuclear Information System (INIS)
Fuller, George M.
1999-01-01
The existence of small mixings between light active and sterile neutrino species could have implications for Big Bang and Supernova Heavy Element Nucleosynthesis. As well, such mixing would force us to abandon cherished constraints on light neutrino Dark Matter. Two proposed 4-neutrino mass and mixing schemes, for example, can both accomodate existing experimental results and lead to elegant solutions to the neutron-deficit problem for r-Process nucleosynthesis from neutrino-heated supernova ejecta. Each of these solutions is based on matter-enhanced (MSW) active-sterile neutrino transformation. In plausible extensions of these schemes to the early universe, Shi and Fuller have shown that relatively light mass (∼200 eV to ∼10 keV) sterile neutrinos produced via active-sterile MSW conversion can have a ''cold'' energy spectrum. Neutrinos produced in this way circumvent the principal problem of light neutrino dark matter and would be, essentially, Cold Dark Matter
Neutrino masses, lepton number violation and unification
Barbieri, Riccardo
1980-01-01
Theories with parity as a short-distance symmetry lead rather naturally to a small but non-vanishing nu L/sub 2/ mass. A reference formula for the size of the effect is m/sub nu / approximately=m/sup 2 //M with M a huge Majorana mass of the nu /sub R/ field, associated with the breaking of the group down to SU(3)*SU(2)*U(1) and m a typical quark mass, most likely that of charge 2/3. This is because of the Pati-Salam SU(4) which relates neutrinos with charge 2/3 quarks, and is contained in the prototypes of these theories, SO(10) or E/sub 6/. Ten GeV for m requires M approximately=10/sup 11/ GeV in order to saturate the cosmological bound (m/sub nu / of a few eV). This value is not too far from the currently preferred mass approximately=10/sup 14/ GeV of the superheavy gauge bosons. In view of these concepts, the search for neutrino oscillations appears to be of overwhelming importance. A combined effort in all different kinds of possible experiments (reactors, accelerators, deep mines, and solar neutrino obse...
Girardi, Ivan
2016-01-01
The experimental evidences of neutrino oscillation, caused by non-zero neutrino masses and neutrino mixing, which were obtained in the experiments with solar, atmospheric, accelerator and reactor neutrinos, opened new field of research in elementary particle physics. The principal goal is to understand at fundamental level the mechanism giving rise to non-zero neutrino masses and neutrino mixing. The open fundamental questions include those of the nature — Dirac or Majorana — of massive neutr...
Neutrino masses and their ordering: global data, priors and models
Gariazzo, S.; Archidiacono, M.; de Salas, P. F.; Mena, O.; Ternes, C. A.; Tórtola, M.
2018-03-01
We present a full Bayesian analysis of the combination of current neutrino oscillation, neutrinoless double beta decay and Cosmic Microwave Background observations. Our major goal is to carefully investigate the possibility to single out one neutrino mass ordering, namely Normal Ordering or Inverted Ordering, with current data. Two possible parametrizations (three neutrino masses versus the lightest neutrino mass plus the two oscillation mass splittings) and priors (linear versus logarithmic) are exhaustively examined. We find that the preference for NO is only driven by neutrino oscillation data. Moreover, the values of the Bayes factor indicate that the evidence for NO is strong only when the scan is performed over the three neutrino masses with logarithmic priors; for every other combination of parameterization and prior, the preference for NO is only weak. As a by-product of our Bayesian analyses, we are able to (a) compare the Bayesian bounds on the neutrino mixing parameters to those obtained by means of frequentist approaches, finding a very good agreement; (b) determine that the lightest neutrino mass plus the two mass splittings parametrization, motivated by the physical observables, is strongly preferred over the three neutrino mass eigenstates scan and (c) find that logarithmic priors guarantee a weakly-to-moderately more efficient sampling of the parameter space. These results establish the optimal strategy to successfully explore the neutrino parameter space, based on the use of the oscillation mass splittings and a logarithmic prior on the lightest neutrino mass, when combining neutrino oscillation data with cosmology and neutrinoless double beta decay. We also show that the limits on the total neutrino mass ∑ mν can change dramatically when moving from one prior to the other. These results have profound implications for future studies on the neutrino mass ordering, as they crucially state the need for self-consistent analyses which explore the
Neutrino mass constraints on β decay
International Nuclear Information System (INIS)
Ito, Takeyasu M.; Prezeau, Gary
2005-01-01
Using the general connection between the upper limit on the neutrino mass and the upper limits on certain types of non-standard-model interactions that can generate loop corrections to the neutrino mass, we derive constraints on some non-standard-model d→ue - ν interactions. When cast into limits on n→pe - ν coupling constants, our results yield constraints on scalar and tensor weak interactions improved by more than an order of magnitude over the current experimental limits. When combined with the existing limits, our results yield vertical bar C S /C V vertical bar or approx. 5x10 -3 , vertical bar C S ' /C V vertical bar or approx. 5x10 -3 , vertical bar C T /C A vertical bar -2 , and vertical bar C T ' /C A vertical bar -2
Chiral condensate from the twisted mass Dirac operator spectrum
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Collaboration: European Twisted Mass Collaboration
2013-03-15
We present the results of our computation of the chiral condensate with N{sub f}=2 and N{sub f}=2+1+1 flavours of maximally twisted mass fermions. The condensate is determined from the Dirac operator spectrum, applying the spectral projector method proposed by Giusti and Luescher. We use 3 lattice spacings and several quark masses at each lattice spacing to reliably perform the chiral and continuum extrapolations. We study the effect of the dynamical strange and charm quarks by comparing our results for N{sub f}=2 and N{sub f}=2+1+1 dynamical flavours.
Chiral condensate from the twisted mass Dirac operator spectrum
International Nuclear Information System (INIS)
Cichy, Krzysztof; Jansen, Karl; Cyprus Univ., Nicosia
2013-03-01
We present the results of our computation of the chiral condensate with N f =2 and N f =2+1+1 flavours of maximally twisted mass fermions. The condensate is determined from the Dirac operator spectrum, applying the spectral projector method proposed by Giusti and Luescher. We use 3 lattice spacings and several quark masses at each lattice spacing to reliably perform the chiral and continuum extrapolations. We study the effect of the dynamical strange and charm quarks by comparing our results for N f =2 and N f =2+1+1 dynamical flavours.
Nonstandard Supersymmetry Breaking and Dirac Gaugino Masses without Supersoftness
Energy Technology Data Exchange (ETDEWEB)
Martin, Stephen P. [Northern Illinois U.
2015-08-05
I consider models in which nonstandard supersymmetry-breaking terms, including Dirac gaugino masses, arise from F-term breaking mediated by operators with a 1/M3 suppression. In these models, the supersoft properties found in the case of D-term breaking are absent in general, but can be obtained as a special case that is a fixed point of the renormalization group equations. The μ term is replaced by three distinct supersymmetry-breaking parameters, decoupling the Higgs scalar potential from the Higgsino masses. Both holomorphic and nonholomorphic scalar cubic interactions with minimal flavor violation are induced in the supersymmetric Standard Model Lagrangian.
Theory of Neutrino Masses and Mixing
González-Garciá, M Concepción
2003-01-01
In this talk I will review our present knowledge on neutrino masses and mixing trying to emphasize what has been definitively proved and what is in the process of being probed. I will also discuss the most important theoretical implications of these results: the existence of new physics, the estimate of the scale of this new physics as well as some other possible consequences such as leptogenesis origin of the baryon asymmetry.
Mass limits for the muon neutrino
International Nuclear Information System (INIS)
Hoffman, C.M.; Sandberg, V.D.
1982-01-01
The possibility of improving the present limit on the mass of the muon neutrino is discussed. It is found that decays of muons and pions are not useful means to significantly improve this limit. On the other hand, the decays K 0 /sub L/ → π/sup +-/μ/sup -+/nu/sub μ/ and K + → π 0 μ + nu/sub μ/ appear to be quite promising. Possible experiments are discussed
Texture zeros in neutrino mass matrix
Energy Technology Data Exchange (ETDEWEB)
Dziewit, B., E-mail: bartosz.dziewit@us.edu.pl; Holeczek, J., E-mail: jacek.holeczek@us.edu.pl; Richter, M., E-mail: monikarichter18@gmail.com [University of Silesia, Institute of Physics (Poland); Zajac, S., E-mail: s.zajac@uksw.edu.pl [Cardinal Stefan Wyszyński University in Warsaw, Faculty of Mathematics and Natural Studies (Poland); Zralek, M., E-mail: marek.zralek@us.edu.pl [University of Silesia, Institute of Physics (Poland)
2017-03-15
The Standard Model does not explain the hierarchy problem. Before the discovery of nonzero lepton mixing angle θ{sub 13} high hopes in explanation of the shape of the lepton mixing matrix were combined with non-Abelian symmetries. Nowadays, assuming one Higgs doublet, it is unlikely that this is still valid. Texture zeroes, that are combined with abelian symmetries, are intensively studied. The neutrino mass matrix is a natural way to study such symmetries.
Cosmology and the neutrino mass ordering
DEFF Research Database (Denmark)
Hannestad, Steen; Schwetz, Thomas
2016-01-01
We propose a simple method to quantify a possible exclusion of the inverted neutrino mass ordering from cosmological bounds on the sum of the neutrino masses. The method is based on Bayesian inference and allows for a calculation of the posterior odds of normal versus inverted ordering. We apply...... the method for a specific set of current data from Planck CMB data and large-scale structure surveys, providing an upper bound on the sum of neutrino masses of 0.14 eV at 95% CL. With this analysis we obtain posterior odds for normal versus inverted ordering of about 2:1. If cosmological data is combined...... with data from oscillation experiments the odds reduce to about 3:2. For an exclusion of the inverted ordering from cosmology at more than 95% CL, an accuracy of better than 0.02 eV is needed for the sum. We demonstrate that such a value could be reached with planned observations of large scale structure...
Absolute values of neutrino masses: status and prospects
International Nuclear Information System (INIS)
Bilenky, S.M.; Giunti, C.; Grifols, J.A.; Masso, E.
2003-01-01
Compelling evidences in favor of neutrino masses and mixing obtained in the last years in Super-Kamiokande, SNO, KamLAND and other neutrino experiments made the physics of massive and mixed neutrinos a frontier field of research in particle physics and astrophysics. There are many open problems in this new field. In this review we consider the problem of the absolute values of neutrino masses, which apparently is the most difficult one from the experimental point of view. We discuss the present limits and the future prospects of β-decay neutrino mass measurements and neutrinoless double-β decay. We consider the important problem of the calculation of nuclear matrix elements of neutrinoless double-β decay and discuss the possibility to check the results of different model calculations of the nuclear matrix elements through their comparison with the experimental data. We discuss the upper bound of the total mass of neutrinos that was obtained recently from the data of the 2dF Galaxy Redshift Survey and other cosmological data and we discuss future prospects of the cosmological measurements of the total mass of neutrinos. We discuss also the possibility to obtain information on neutrino masses from the observation of the ultra high-energy cosmic rays (beyond the GZK cutoff). Finally, we review the main aspects of the physics of core-collapse supernovae, the limits on the absolute values of neutrino masses from the observation of SN1987A neutrinos and the future prospects of supernova neutrino detection
Finding Mass Constraints Through Third Neutrino Mass Eigenstate Decay
Gangolli, Nakul; de Gouvêa, André; Kelly, Kevin
2018-01-01
In this paper we aim to constrain the decay parameter for the third neutrino mass utilizing already accepted constraints on the other mixing parameters from the Pontecorvo-Maki-Nakagawa-Sakata matrix (PMNS). The main purpose of this project is to determine the parameters that will allow the Jiangmen Underground Neutrino Observatory (JUNO) to observe a decay parameter with some statistical significance. Another goal is to determine the parameters that JUNO could detect in the case that the third neutrino mass is lighter than the first two neutrino species. We also replicate the results that were found in the JUNO Conceptual Design Report (CDR). By utilizing Χ2-squared analysis constraints have been put on the mixing angles, mass squared differences, and the third neutrino decay parameter. These statistical tests take into account background noise and normalization corrections and thus the finalized bounds are a good approximation for the true bounds that JUNO can detect. If the decay parameter is not included in our models, the 99% confidence interval lies within The bounds 0s to 2.80x10-12s. However, if we account for a decay parameter of 3x10-5 ev2, then 99% confidence interval lies within 8.73x10-12s to 8.73x10-11s.
Constraining dynamical neutrino mass generation with cosmological data
Energy Technology Data Exchange (ETDEWEB)
Koksbang, S.M.; Hannestad, S., E-mail: koksbang@phys.au.dk, E-mail: sth@phys.au.dk [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)
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.
Neutrino mass and mixing with discrete symmetry
International Nuclear Information System (INIS)
King, Stephen F; Luhn, Christoph
2013-01-01
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 A 4 , S 4 and Δ(96). (review article)
Nonzero θ13 and neutrino masses from the modified tri-bi-maximal neutrino mixing matrix
International Nuclear Information System (INIS)
Damanik, A.
2014-01-01
There are 3 types of neutrino mixing matrices: tri-bi-maximal, bi-maximal and democratic. These 3 types of neutrino mixing matrices predict that the mixing angle θ 13 should be null. Motivated by the recent experimental evidence of nonzero and relatively large θ 13 , we modified the tribimaximal mixing matrix by introducing a simple perturbation matrix into tribimaximal neutrino mixing matrix. In this scenario, we obtained nonzero mixing angle θ 13 =7.9 degrees which is in agreement with the present experimental results. By imposing 2 zeros texture into the obtained neutrino mass matrix from modified tribimaximal mixing matrix, we then have the neutrino mass spectrum in normal hierarchy. Some phenomenological implications are also discussed. It appears that if we use the solar neutrino squared-mass difference to determine the values of neutrino masses, then we cannot have the correct value for the atmospheric squared-mass difference. Conversely, if we use the experimental value of the squared-mass difference to determine the neutrino masses, then we cannot have the correct value for the solar neutrino squared-mass difference
Ando, Shin'ichiro; Sato, Katsuhiko
2003-10-01
Resonant spin-flavour (RSF) conversions of supernova neutrinos, which are induced by the interaction between the nonzero neutrino magnetic moment and supernova magnetic fields, are studied for both normal and inverted mass hierarchy. As the case for the pure matter-induced neutrino oscillation (Mikheyev–Smirnov–Wolfenstein (MSW) effect), we find that the RSF transitions are strongly dependent on the neutrino mass hierarchy as well as the value of θ13. Flavour conversions are solved numerically for various neutrino parameter sets, with the presupernova profile calculated by Woosley and Weaver. In particular, it is very interesting that the RSF-induced νe→bar nue transition occurs if the following conditions are all satisfied: the value of μνB (μν is the neutrino magnetic moment and B is the magnetic field strength) is sufficiently strong, the neutrino mass hierarchy is inverted, and the value of θ13 is large enough to induce adiabatic MSW resonance. In this case, the strong peak due to the original νe emitted from the neutronization burst would exist in the time profile of the neutrino events detected at the Super-Kamiokande detector. If this peak were observed in reality, it would provide fruitful information on the neutrino properties. On the other hand, the characteristics of the neutrino spectra are also different between the neutrino models, but we find that there remains degeneracy among several models. Dependence on presupernova models is also discussed.
The neutrino masses in SO(10) grand unified theory
International Nuclear Information System (INIS)
Leontaris, G.K.; Vergados, J.D.; Ioannina Univ.
1987-01-01
The neutrino masses and mixing are investigated in an SO(10) model in which the ten-dimensional and 126-dimensional representations are allowed to obtain vacuum expectation values. The parameters specifying the heavy Majorana neutrino mass matrix are constrained from the cosmological bound of light neutrino masses and the limits from ν μ ↔ ν τ oscillations. The implications of our model on 0ν-ββ decay and muon-number violating processes are explored. (orig.)
Hierarchical Neutrino Masses and Mixing in Flipped-SU(5)
Rizos, J
2010-01-01
We consider the problem of neutrino masses and mixing in the framework of flipped SU(5). The right-handed neutrino mass, generated through the operation of a seesaw mechanism by a sector of gauge singlets, leads naturally, at a subsequent level, to the standard seesaw mechanism resulting into three light neutrino states with masses of the desired phenomenological order of magnitude. In this framework we study simple Ansatze for the singlet couplings for which hierarchical neutrino masses emerge naturally, parametrized in terms of the Cabbibo parameter. The resulting neutrino mixing matrices are characterized by a hierarchical structure, in which theta-(13) is always predicted to be the smallest. Finally, we discuss a possible factorized parametrization of the neutrino mass that, in addition to Cabbibo mixing, encodes also mixing due to the singlet sector.
Hierarchical neutrino masses and mixing in flipped-SU(5)
Energy Technology Data Exchange (ETDEWEB)
Rizos, J. [Physics Department, University of Ioannina, 45110 Ioannina (Greece); Tamvakis, K., E-mail: tamvakis@uoi.g [Physics Department, University of Ioannina, 45110 Ioannina (Greece); Physics Department, CERN, CH-1211, Geneva 23 (Switzerland)
2010-02-22
We consider the problem of neutrino masses and mixing in the framework of flipped SU(5). The right-handed neutrino mass, generated through the operation of a seesaw mechanism by a sector of gauge singlets, leads naturally, at a subsequent level, to the standard seesaw mechanism resulting into three light neutrino states with masses of the desired phenomenological order of magnitude. In this framework we study simple Ansaetze for the singlet couplings for which hierarchical neutrino masses emerge naturally as lambda{sup n}:lambda:1 or lambda{sup n}:lambda{sup 2}:1, parametrized in terms of the Cabbibo parameter. The resulting neutrino mixing matrices are characterized by a hierarchical structure, in which theta{sub 13} is always predicted to be the smallest. Finally, we discuss a possible factorized parametrization of the neutrino mass that, in addition to Cabbibo mixing, encodes also mixing due to the singlet sector.
Dark matter and neutrino mass from the smallest non-Abelian chiral dark sector
Berryman, Jeffrey M.; de Gouvêa, André; Kelly, Kevin J.; Zhang, Yue
2017-10-01
All pieces of concrete evidence for phenomena outside the standard model (SM)—neutrino masses and dark matter—are consistent with the existence of new degrees of freedom that interact very weakly, if at all, with those in the SM. We propose that these new degrees of freedom organize themselves into a simple dark sector, a chiral S U (3 )×S U (2 ) gauge theory with the smallest nontrivial fermion content. Similar to the SM, the dark S U (2 ) is spontaneously broken while the dark S U (3 ) confines at low energies. At the renormalizable level, the dark sector contains massless fermions—dark leptons—and stable massive particles—dark protons. We find that dark protons with masses between 10 and 100 TeV satisfy all current cosmological and astrophysical observations concerning dark matter even if dark protons are a symmetric thermal relic. The dark leptons play the role of right-handed neutrinos and allow simple realizations of the seesaw mechanism or the possibility that neutrinos are Dirac fermions. In the latter case, neutrino masses are also parametrically different from charged-fermion masses and the lightest neutrino is predicted to be massless. Since the new "neutrino" and "dark-matter" degrees of freedom interact with one another, these two new-physics phenomena are intertwined. Dark leptons play a nontrivial role in early Universe cosmology while indirect searches for dark matter involve, decisively, dark-matter annihilations into dark leptons. These, in turn, may lead to observable signatures at high-energy neutrino and gamma-ray observatories, especially once one accounts for the potential Sommerfeld enhancement of the annihilation cross section, derived from the low-energy dark-sector effective theory, a possibility we explore quantitatively in some detail.
Massive neutrinos in particle physics and astrophysics
International Nuclear Information System (INIS)
Rosen, S.P.
1986-01-01
The concepts of Majorana and Dirac neutrinos are reviewed from an operational point of view and survey the experimental search for neutrino mass. Also reviewed are the work of Mikheyev and Smirnov on the enhancement of neutrino oscillations via the mechanism of Wolfenstein matter oscillations. Results of an extensive computation of MSW effects in the sun are described. 41 refs., 6 figs
NEUTRINO mass textures and the nature of new physics implied by present neutrino data
International Nuclear Information System (INIS)
Mohapatra, R.N.
1997-01-01
If all the indications for neutrino oscillations observed in the solar, atmospheric neutrino data as well as in the LSND experiment are borned out by the ongoing and future experiments, then they severely constrain the neutrino mass texture. In particular, the need for an extra ultra-light sterile neutrino species is hard to avoid. Such an extra neutrino has profound implication not only for physics beyond the standard model but even perhaps for physics beyond conventional grand unification. A scenario involving a parallel (or shadow) universe that interacts with the familiar universe only via the gravitational interactions where the ultra-lightness of the sterile neutrino follows from the same physics that explains the near masslessness of the familiar neutrinos is discussed in the presentation
Relaxing neutrino mass bounds by a running cosmological constant
Energy Technology Data Exchange (ETDEWEB)
Bauer, F.; Schrempp, L.
2007-11-15
We establish an indirect link between relic neutrinos and the dark energy sector which originates from the vacuum energy contributions of the neutrino quantum fields. Via renormalization group effects they induce a running of the cosmological constant with time which dynamically influences the evolution of the cosmic neutrino background. We demonstrate that the resulting reduction of the relic neutrino abundance allows to largely evade current cosmological neutrino mass bounds and discuss how the scenario might be probed by the help of future large scale structure surveys and Planck data. (orig.)
Relaxing neutrino mass bounds by a running cosmological constant
International Nuclear Information System (INIS)
Bauer, F.; Schrempp, L.
2007-11-01
We establish an indirect link between relic neutrinos and the dark energy sector which originates from the vacuum energy contributions of the neutrino quantum fields. Via renormalization group effects they induce a running of the cosmological constant with time which dynamically influences the evolution of the cosmic neutrino background. We demonstrate that the resulting reduction of the relic neutrino abundance allows to largely evade current cosmological neutrino mass bounds and discuss how the scenario might be probed by the help of future large scale structure surveys and Planck data. (orig.)
Limit on the tau neutrino mass
International Nuclear Information System (INIS)
Cinabro, D.; Henderson, S.; Kinoshita, K.; Liu, T.; Saulnier, M.; Wilson, R.; Yamamoto, H.; Sadoff, A.J.; Ammar, R.; Ball, S.; Baringer, P.; Coppage, D.; Copty, N.; Davis, R.; Hancock, N.; Kelly, M.; Kwak, N.; Lam, H.; Kubota, Y.; Lattery, M.; Nelson, J.K.; Patton, S.; Perticone, D.; Poling, R.; Savinov, V.; Schrenk, S.; Wang, R.; Alam, M.S.; Kim, I.J.; Nemati, B.; O'Neill, J.J.; Romero, V.; Severini, H.; Sun, C.R.; Zoeller, M.M.; Crawford, G.; Fulton, R.; Fujino, D.; Gan, K.K.; Kagan, H.; Kass, R.; Lee, J.; Malchow, R.; Morrow, F.; Skovpen, Y.; Sung, M.; White, C.; Whitmore, J.; Wilson, P.; Butler, F.; Fu, X.; Kalbfleisch, G.; Lambrecht, M.; Ross, W.R.; Skubic, P.; Snow, J.; Wang, P.L.; Wood, M.; Bortoletto, D.; Brown, D.N.; Dominick, J.; McIlwain, R.L.; Miao, T.; Miller, D.H.; Modesitt, M.; Schaffner, S.F.; Shibata, E.I.; Shipsey, I.P.J.; Wang, P.N.; Battle, M.; Ernst, J.; Kroha, H.; Roberts, S.; Sparks, K.; Thorndike, E.H.; Wang, C.H.; Sanghera, S.; Skwarnicki, T.; Stroynowski, R.; Artuso, M.; He, D.; Goldberg, M.; Horwitz, N.; Kennett, R.; Moneti, G.C.; Muheim, F.; Mukhin, Y.; Playfer, S.; Rozen, Y.; Rubin, P.; Stone, S.; Thulasidas, M.; Vasseur, G.; Zhu, G.; Barnes, A.V.; Bartelt, J.; Csorna, S.E.; Egyed, Z.; Jain, V.; Sheldon, P.; Akerib, D.S.; Barish, B.; Chadha, M.; Chan, S.; Cowen, D.F.; Eigen, G.; Miller, J.S.; Urheim, J.; Weinstein, A.J.; Acosta, D.; Athanas, M.; Masek, G.; Ong, B.; Paar, H.; Sivertz, M.; Bean, A.; Gronberg, J.; Kutschke, R.; Menary, S.; Morrison, R.J.; Nakanishi, S.; Nelson, H.N.; Nelson, T.K.; Richman, J.D.; Tajima, H.; Schmidt, D.; Sperka, D.; Witherell, M.S.; Procario, M.; Yang, S.; Balest, R.; Cho, K.; Daoudi, M.; Ford, W.T.; Johnson, D.R.; Lingel, K.; Lohner, M.; Rankin, P.; Smith, J.G.; Alexander, J.P.; Bebek, C.; Berkelman, K.; Besson, D.; Browder, T.E.; Cassel, D.G.; Cho, H.A.; Coffman, D.M.; Drell, P.S.; Ehrlich, R.; Galik, R.S.; Garcia-Sciveres, M.; Geiser, B.; Gittelman, B.; Gray, S.W.; Hartill, D.L.; Heltsley, B.
1993-01-01
A limit on the tau neutrino mass M ντ is obtained from a study of tau decays in the reaction e + e-→τ + τ - at center-of-mass energies ∼10.6 GeV. The result is based on an end-point analysis of the invariant mass spectrum of the decay products in the decay modes τ - →3h - 2h + ν τ and τ - →2h - h+2π 0 ν τ . The data sample used in this analysis contains 1.77x10 6 tau pairs, corresponding to an integrated luminosity of 1.92 fb -1 , and is substantially larger than previous data samples used to place a limit on M ντ . The limit obtained for both five-hadron modes together is 32.6 MeV at 95% C.L
Geometrical neutrino mass hierarchy and a 17-keV ντ
International Nuclear Information System (INIS)
Babu, K.S.; Mohapatra, R.N.
1991-01-01
We present an extension of the singlet majoron gauge model which realizes a novel scheme of geometrical neutrino mass hierarchy proposed recently by Glashow, wherein ν e and ν μ are Majorana particles with m νe ∼m νμ ∼10 -3 eV while ν τ is a Dirac particle with a mass of 17 keV. Our model explains the solar-neutrino deficit via the Mikheyev-Smirnov-Wolfenstein mechanism and accounts for the recently reported anomaly in beta-decay spectra in a natural manner without any undesirable fine tuning of parameters. An interesting consequence of the model is that ν τ is short lived with a lifetime of ∼10 -3-- 10 -1 sec
CERN. Geneva; Dydak, Friedrich
2001-01-01
Starting from a review of theoretical concepts and experimental results in the early years of neutrino physics after Pauli's 1930 letter, today's double role of the neutrino as a cornerstone of the Standard Model and as a promising probe of physics beyond the Standard Model will be discussed. Topics comprise: - Conventional neutrino beams - Neutrinos as probes of the nucleon structure - Neutrinos from the universe - Dirac or Majorana neutrinos - Neutrino oscillations - MNS matrix - CP violation in the lepton sector - Neutrino factory.
CERN. Geneva. Audiovisual Unit
2002-01-01
Starting from a review of theoretical concepts and experimental results in the early years of neutrino physics after Pauli's 1930 letter, today's double role of the neutrino as a cornerstone of the Standard Model and as a promising probe of physics beyond the Standard Model will be discussed. Topics comprise: - Conventional neutrino beams - Neutrinos as probes of the nucleon structure - Neutrinos from the universe - Dirac or Majorana neutrinos - Neutrino oscillations - MNS matrix - CP violation in the lepton sector - Neutrino factory.
Verifiable origin of neutrino mass at TeV scale
International Nuclear Information System (INIS)
Ma, Ernest
2002-01-01
The physics responsible for neutrino mass may reside at or below the TeV energy scale. The neutrino mass matrix in the (ν e ν μ ν gt ) basis may then be deduced from future high-energy accelerator experiments. The newly observed excess in the muon anomalous magnetic moment may also be related
Hybrid method to resolve the neutrino mass hierarchy by supernova (anti)neutrino induced reactions
Energy Technology Data Exchange (ETDEWEB)
Vale, D. [Department of Physics, Faculty of Science, University of Zagreb, Bijenička c. 32, HR-10000 Zagreb (Croatia); Rauscher, T. [Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Paar, N., E-mail: dvale@phy.hr, E-mail: Thomas.Rauscher@unibas.ch, E-mail: npaar@phy.hr [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland)
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.
Hybrid method to resolve the neutrino mass hierarchy by supernova (anti)neutrino induced reactions
Vale, D.; Rauscher, T.; Paar, N.
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 56Fe and 208Pb 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(bar nue,e+)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 νe- and bar nue-induced particle emissions. This hybrid method favors neutrinos from the supernova cooling phase and the implementation of detectors with heavier target nuclei (208Pb) for the neutrino sector, while for antineutrinos the use of free protons in mineral oil or water is the appropriate choice.
Unification of gauge couplings in radiative neutrino mass models
DEFF Research Database (Denmark)
Hagedorn, Claudia; Ohlsson, Tommy; Riad, Stella
2016-01-01
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......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 ΔL = 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...
Neutrino mass in flavor dependent gauged lepton model
Nomura, Takaaki; Okada, Hiroshi
2018-03-01
We study a neutrino model introducing an additional nontrivial gauged lepton symmetry where the neutrino masses are induced at two-loop level, while the first and second charged-leptons of the standard model are done at one-loop level. As a result of the model structure, we can predict one massless active neutrino, and there is a dark matter candidate. Then we discuss the neutrino mass matrix, muon anomalous magnetic moment, lepton flavor violations, oblique parameters, and relic density of dark matter, taking into account the experimental constraints.
International Nuclear Information System (INIS)
Blennow, Mattias
2008-01-01
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
Introduction to the physics of massive and mixed neutrinos
Bilenky, Samoil
2018-01-01
Small neutrino masses are the first signs of new physics beyond the Standard Model of particle physics. Since the first edition of this textbook appeared in 2010, the Nobel Prize has been awarded "for the discovery of neutrino oscillations, which shows that neutrinos have mass". The measurement of the small neutrino mixing angle $\\theta_{13}$ in 2012, launched the precision stage of the investigation of neutrino oscillations. This measurement now allows such fundamental problems as the three-neutrino mass spectrum - is it normal or inverted? – and the $CP$ violation in the lepton sector to be tackled. In order to understand the origin of small neutrino masses, it remains crucial to reveal the nature of neutrinos with definite masses: are they Dirac neutrinos possessing a conserved lepton number, which distinguishes neutrinos and antineutrinos, or are they Majorana neutrinos with identical neutrinos and antineutrinos? Experiments searching for the neutrinoless double beta decay are presently under way to ans...
Probing neutrino masses with CMB lensing extraction
International Nuclear Information System (INIS)
Lesgourgues, Julien; Perotto, Laurence; Pastor, Sergio; Piat, Michel
2006-01-01
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 ν indicated by current neutrino oscillation data. We find that these experiments greatly benefit from lensing extraction techniques, improving their one-sigma sensitivity to M ν by a factor of order four. The combination of data from Planck and the SAMPAN mini-satellite project would lead to σ(M ν )∼0.1 eV, while a value as small as σ(M ν )∼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 (Λ 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
Earth Effects and Mass Hierarchy with Supernova Neutrinos
International Nuclear Information System (INIS)
Dasgupta, Basudeb
2009-01-01
Collective neutrino flavor transformations take place deep inside a supernova if the neutrino mass hierarchy is inverted, even for extremely small values of θ 13 . We show that the presence (or absence) of Earth matter effects in antineutrino signal is directly related to the absence (or presence) of these collective effects, when the mixing angle θ 13 is small. Thus a neutrino signal from a galactic supernova may enable us to distinguish between the hierarchies even for small values of θ 13 .
Higgs mass from neutrino-messenger mixing
International Nuclear Information System (INIS)
Byakti, Pritibhajan; Khosa, Charanjit K.; Mummidi, V.S.; Vempati, Sudhir K.
2017-01-01
The discovery of the Higgs particle at 125 GeV has put strong constraints on minimal messenger models of gauge mediation, pushing the stop masses into the multi-TeV regime. Extensions of these models with matter-messenger mixing terms have been proposed to generate a large trilinear parameter, A t , relaxing these constraints. The detailed survey of these models (DOI: 10.1007/JHEP05(2013)055; 10.1007/JHEP08(2013)093 ) 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.
Higgs mass from neutrino-messenger mixing
Energy Technology Data Exchange (ETDEWEB)
Byakti, Pritibhajan [Center for High Energy Physics, Indian Institute of Science,C.V. Raman Ave, Bangalore 560012 (India); Department of Theoretical Physics, Indian Association for the Cultivation of Science,2A & 2B Raja S.C. Mullick Road, Kolkata 700 032 (India); Khosa, Charanjit K. [Center for High Energy Physics, Indian Institute of Science,C.V. Raman Ave, Bangalore 560012 (India); Mummidi, V.S. [Harish-Chandra Research Institute,Chhatnag Road, Jhusi, Allahabad 211019 (India); Vempati, Sudhir K. [Center for High Energy Physics, Indian Institute of Science,C.V. Raman Ave, Bangalore 560012 (India)
2017-03-06
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{sub t}, relaxing these constraints. The detailed survey of these models (DOI: 10.1007/JHEP05(2013)055; 10.1007/JHEP08(2013)093 ) 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.
Neutrino mass matrices with vanishing determinant
International Nuclear Information System (INIS)
Chauhan, Bhag C.; Pulido, Joao; Picariello, Marco
2006-01-01
We investigate the prospects for neutrinoless double beta decay, texture zeros. and equalities between neutrino mass matrix elements in scenarios with vanishing determinant mass matrices for vanishing and finite θ 13 mixing angles in normal and inverse mass hierarchies. For normal hierarchy and both zero and finite θ 13 it is found that neutrinoless double beta decay cannot be observed by any of the present or next generation experiments, while for inverse hierarchy it is, on the contrary, accessible to experiments. Regarding texture zeros and equalities between mass matrix elements, we find that in both normal and inverse hierarchies with θ 13 =0 no texture zeros nor any such equalities can exist apart from the obvious ones. For θ 13 ≠0 some texture zeros become possible. In normal hierarchy two texture zeros occur if 8.1x10 -2 ≤sinθ 13 ≤9.1x10 -2 while in inverse hierarchy three are possible, one with sinθ 13 ≥7x10 -3 and two others with sinθ 13 ≥0.18. All equalities between mass matrix elements are impossible with θ 13 ≠0
Baryogenesis, neutrino masses, and dynamical dark energy
International Nuclear Information System (INIS)
Eisele, M.T.
2007-01-01
This thesis considers several models that connect different areas of particle physics and cosmology. Our first discussion in this context concerns a baryogenesis scenario, in which the baryon asymmetry of our universe is created through the dynamics of a dark energy field, thereby illustrating that these two topics might be related. Subsequently, several neutrino mass models are analyzed, which make use of an extra-dimensional setting to overcome certain problems of their fourdimensional counterparts. The central discussion of this thesis concerns a leptogenesis model with many standard model singlets. Amongst other things, we show that the presence of these states can lower the standard bound for the necessary reheating temperature of the universe by at least one and a half orders of magnitude. To further motivate this approach, we also discuss an explicit, extradimensional leptogenesis scenario that naturally yields many of the ingredients required in this context. (orig.)
Baryogenesis, neutrino masses, and dynamical dark energy
Energy Technology Data Exchange (ETDEWEB)
Eisele, M.T.
2007-10-09
This thesis considers several models that connect different areas of particle physics and cosmology. Our first discussion in this context concerns a baryogenesis scenario, in which the baryon asymmetry of our universe is created through the dynamics of a dark energy field, thereby illustrating that these two topics might be related. Subsequently, several neutrino mass models are analyzed, which make use of an extra-dimensional setting to overcome certain problems of their fourdimensional counterparts. The central discussion of this thesis concerns a leptogenesis model with many standard model singlets. Amongst other things, we show that the presence of these states can lower the standard bound for the necessary reheating temperature of the universe by at least one and a half orders of magnitude. To further motivate this approach, we also discuss an explicit, extradimensional leptogenesis scenario that naturally yields many of the ingredients required in this context. (orig.)
Sinha, Roopam; Samanta, Rome; Ghosal, Ambar
2017-12-01
We investigate the consequences of a generalized ℤ 2 × ℤ 2 symmetry on a scaling neutrino Majorana mass matrix. It enables us to determine definite analytical relations between the mixing angles θ 12 and θ 13, maximal CP violation for the Dirac type and vanishing for the Majorana type. Beside the other testable predictions on the low energy neutrino parameters such as ββ 0ν decay matrix element | M ee | and the light neutrino masses m 1,2,3, the model also has intriguing consequences from the perspective of leptogenesis. With the assumption that the required CP violation for leptogenesis is created by the decay of lightest ( N 1) of the heavy Majorana neutrinos, only τ -flavored leptogenesis scenario is found to be allowed in this model. For a normal (inverted) ordering of light neutrino masses, θ 23 is found be less (greater) than its maximal value, for the final baryon asymmetry Y B to be in the observed range. Besides, an upper and a lower bound on the mass of N 1 have also been estimated. Effect of the heavier neutrinos N 2,3 on final Y B has been worked out subsequently. The predictions of this model will be tested in the experiments such as nEXO, LEGEND, GERDA-II, T2K, NO νA, DUNE etc.
Energy Technology Data Exchange (ETDEWEB)
Tsirigotis, A. G. [Physics Laboratory, Hellenic Open University (Greece); 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.
Leptogenesis in a neutrino mass model coupled with inflaton
Directory of Open Access Journals (Sweden)
Daijiro Suematsu
2016-09-01
Full Text Available We propose a scenario for the generation of baryon number asymmetry based on the inflaton decay in a radiative neutrino mass model extended with singlet scalars. In this scenario, lepton number asymmetry is produced through the decay of non-thermal right-handed neutrinos caused from the inflaton decay. Since the amount of non-thermal right-handed neutrinos could be much larger than the thermal ones, the scenario could work without any resonance effect for rather low reheating temperature. Sufficient baryon number asymmetry can be generated for much lighter right-handed neutrinos compared with the Davidson–Ibarra bound.
The high mass frontier: limits on heavy neutrinos
International Nuclear Information System (INIS)
Gronau, M.
1984-01-01
The theoretical motivation for a search for heavy neutrinos is discussed followed by the presentation of typical model dependent expectations for the mixing of the latter with ordinary neutrinos. Present mass and mixing limits on such heavy neutral leptons are based on search for secondary peaks in π and K leptonic decays and on the absence of neutrino decay signatures in neutrino beams from conventional sources and beam dumps. While these limits are quite poor for masses above 1 GeV, we describe methods to extend the limits to masses in the many GeV region. Such limits may be derived from search in b decays, high statistics neutrino experiments, search in ep colliders, W and Z decays and finally - decays of very heavy gauge bosons (if such exist in the TeV region) when produced in multi-TeV pp and antipp colliders
The Neutrino Bomb: A New Weapon of Mass Destruction
International Nuclear Information System (INIS)
Broda, E.
1978-01-01
This text was written by E. Broda in a “Supplementary” paper for Pugwash in the year 1978. It is about the neutrino and a general principle of its use as a potential weapon of mass destruction. It ends with a suggestion to convene a Pugwash workshop for dealing with the threat of the neutrino bomb. (zarka)
Neutrino Mass Models: impact of non-zero reactor angle
International Nuclear Information System (INIS)
King, Stephen F.
2011-01-01
In this talk neutrino mass models are reviewed and the impact of a non-zero reactor angle and other deviations from tri-bi maximal mixing are discussed. We propose some benchmark models, where the only way to discriminate between them is by high precision neutrino oscillation experiments.
Disappearing neutrinos at KamLAND suport the case for neutrino mass
Johnson, G
2002-01-01
Measurements from KamLAND, show that anti-neutrinos emanating from nearby nuclear reactors are "disappearing," which indicates they have mass and can oscillate or change from one type to another (2 pages)
A see-saw mechanism with light sterile neutrinos
International Nuclear Information System (INIS)
McKellar, B.H.J.; Garbutt, M.; Stephenson, G.J.; Goldman, T.
2001-01-01
The usual see-saw mechanism for the generation of light neutrino masses is based on the assumption that all of the flavours of right-handed (more properly, sterile) neutrinos are heavy. If the sterile Majorana mass matrix is singular, one or more of the sterile neutrinos will have zero mass before mixing with the active (left-handed) neutrinos and be light after that mixing is introduced In particular, a rank 1 sterile mass matrix leads naturally to two pseudo-Dirac pairs, one very light active Majorana neutrino and one heavy sterile Majorana neutrino. For any pattern of Dirac masses, there exists a region of parameter space in which the two pseudo-Dirac pairs are nearly degenerate in mass. This, in turn, leads to large amplitude mixing of active states as well as mixing into sterile states
Neutrinos: in and out of the standard model
Energy Technology Data Exchange (ETDEWEB)
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.
Trinification, the hierarchy problem, and inverse seesaw neutrino masses
International Nuclear Information System (INIS)
Cauet, Christophe; Paes, Heinrich; Wiesenfeldt, Soeren
2011-01-01
In minimal trinification models light neutrino masses can be generated via a radiative seesaw mechanism, where the masses of the right-handed neutrinos originate from loops involving Higgs and fermion fields at the unification scale. This mechanism is absent in models aiming at solving or ameliorating the hierarchy problem, such as low-energy supersymmetry, since the large seesaw scale disappears. In this case, neutrino masses need to be generated via a TeV-scale mechanism. In this paper, we investigate an inverse seesaw mechanism and discuss some phenomenological consequences.
Sterile neutrinos in the early universe
Energy Technology Data Exchange (ETDEWEB)
Malaney, R.A. (Lawrence Livermore National Lab., CA (USA)); Fuller, G.M. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Physics)
1990-11-14
We discuss the role played by right-handed sterile neutrinos in the early universe. We show how well known {sup 4}He constraint on the number of relativistic degrees of freedom at early times limits the equilibration of the right handed neutrino sea with the background plasma. We discuss how this allows interesting constraints to be placed on neutrino properties. In particular, a new limit on the Dirac mass of the neutrino is presented. 12 refs.
Gravity wave and neutrino bursts from stellar collapse: A sensitive test of neutrino masses
International Nuclear Information System (INIS)
Arnaud, N.; Barsuglia, M.; Bizouard, M.A.; Cavalier, F.; Davier, M.; Hello, P.; Pradier, T.
2002-01-01
New methods are proposed with the goal to determine absolute neutrino masses from the simultaneous observation of the bursts of neutrinos and gravitational waves emitted during a stellar collapse. It is shown that the neutronization electron neutrino flash and the maximum amplitude of the gravitational wave signal are tightly synchronized with the bounce occurring at the end of the core collapse on a time scale better than 1 ms. The existing underground neutrino detectors (SuperKamiokande, SNO,...) and the gravity wave antennas soon to operate (LIGO, VIRGO,...) are well matched in their performance for detecting galactic supernovae and for making use of the proposed approach. Several methods are described, which apply to the different scenarios depending on neutrino mixing. Given the present knowledge on neutrino oscillations, the methods proposed are sensitive to a mass range where neutrinos would essentially be mass degenerate. The 95% C.L. upper limit which can be achieved varies from 0.75 eV/c 2 for large ν e survival probabilities to 1.1 eV/c 2 when in practice all ν e 's convert into ν μ 's or ν τ 's. The sensitivity is nearly independent of the supernova distance
Reconstructing neutrino properties from collider experiments in a Higgs triplet neutrino mass model
International Nuclear Information System (INIS)
Aristizabal Sierra, D.; Hirsch, M.; Valle, J. W. F.; Villanova del Moral, A.
2003-01-01
We extend the minimal supersymmetric standard model with bilinear R-parity violation to include a pair of Higgs triplet superfields. The neutral components of the Higgs triplets develop small vacuum expectation values (VEVs) quadratic in the bilinear R-parity breaking parameters. In this scheme the atmospheric neutrino mass scale arises from bilinear R-parity breaking while for reasonable values of parameters the solar neutrino mass scale is generated from the small Higgs triplet VEVs. We calculate neutrino masses and mixing angles in this model and show how the model can be tested at future colliders. The branching ratios of the doubly charged triplet decays are related to the solar neutrino angle via a simple formula
Neutrino mass sum rules and symmetries of the mass matrix
Energy Technology Data Exchange (ETDEWEB)
Gehrlein, Julia [Karlsruhe Institute of Technology, Institut fuer Theoretische Teilchenphysik, Karlsruhe (Germany); Universidad Autonoma de Madrid, Departamento de Fisica Teorica, Madrid (Spain); Instituto de Fisica Teorica UAM/CSIC, Madrid (Spain); Spinrath, Martin [Karlsruhe Institute of Technology, Institut fuer Theoretische Teilchenphysik, Karlsruhe (Germany); National Center for Theoretical Sciences, Physics Division, Hsinchu (China)
2017-05-15
Neutrino mass sum rules have recently gained again more attention as a powerful tool to discriminate and test various flavour models in the near future. A related question which has not yet been discussed fully satisfactorily was the origin of these sum rules and if they are related to any residual or accidental symmetry. We will address this open issue here systematically and find previous statements confirmed. Namely, the sum rules are not related to any enhanced symmetry of the Lagrangian after family symmetry breaking but they are simply the result of a reduction of free parameters due to skillful model building. (orig.)
Probing grand unification with fermion masses, neutrino oscillations ...
Indian Academy of Sciences (India)
owing to the contributions from both the standard and the neutrino mass-relatedd =5 op- ..... framework emerges, which successfully accounts for a host of observed phenomena per- ...... conclusion reached by other authors (see especially ref.
Objective Bayesian analysis of neutrino masses and hierarchy
Heavens, Alan F.; Sellentin, Elena
2018-04-01
Given the precision of current neutrino data, priors still impact noticeably the constraints on neutrino masses and their hierarchy. To avoid our understanding of neutrinos being driven by prior assumptions, we construct a prior that is mathematically minimally informative. Using the constructed uninformative prior, we find that the normal hierarchy is favoured but with inconclusive posterior odds of 5.1:1. Better data is hence needed before the neutrino masses and their hierarchy can be well constrained. We find that the next decade of cosmological data should provide conclusive evidence if the normal hierarchy with negligible minimum mass is correct, and if the uncertainty in the sum of neutrino masses drops below 0.025 eV. On the other hand, if neutrinos obey the inverted hierarchy, achieving strong evidence will be difficult with the same uncertainties. Our uninformative prior was constructed from principles of the Objective Bayesian approach. The prior is called a reference prior and is minimally informative in the specific sense that the information gain after collection of data is maximised. The prior is computed for the combination of neutrino oscillation data and cosmological data and still applies if the data improve.
Neutrino mass and the reionization history of the Universe
International Nuclear Information System (INIS)
Popa, L.A.; Burigana, C.; Mandolesi, N.
2005-01-01
We investigate the role of a HDM component in the form of the three massive neutrino flavors for the reionization history of the Universe. Assuming a flat background cosmology described by the best fit power low ΛCDM model with WMAP data (Ω b h 2 =0.024, Ω m h 2 =0.14, h=0.72), we analyze the role of the neutrino mass for the properties of the gas in the intergalactic medium (IGM), showing that the temporal evolution of the hydrogen and helium ionization fractions are sensitive to the neutrino mass, with important implications for the CMB anisotropy and polarization angular power spectra
Origins of tiny neutrino mass and large flavor mixings
International Nuclear Information System (INIS)
Haba, Naoyuki
2015-01-01
Active neutrino masses are extremely smaller than those of other quarks and leptons, and there are large flavor mixings in the lepton sector, contrary to the quark sector. They are great mysteries in the standard model, but also excellent hints of new physics beyond the standard model. Thus, questions 'What is an origin of tiny neutrino mass?' and 'What is an origin of large lepton flavor mixings?' are very important. In this paper, we overview various attempts to solve these big questions. (author)
Limits on neutrino masses from tritium beta decay
Bonn, J; Bornschein, L; Flatt, B; Kraus, C V; Otten, E W; Schall, J P; Thuemmler, T; Weinheimer, C
2002-01-01
The presently lowest limit for the mass of the electron neutrino is m nu < 2.2 eV (95 % C.L.) derived from measurements at Mainz up to 1999. The data taken in 2000 are not fully analyzed yet but limits of possible distortions as reported by the Troitsk group can be given. The next generation neutrino mass experiment KATRIN is briefly discussed.
The Majorana project: sup 7 sup 6 Ge 0 nu beta beta-decay neutrino mass measurement
Aalseth, C E
2002-01-01
Interest in, and the relevance of, next-generation 0 nu beta beta-decay experiments is increasing. Even with nonzero neutrino mass strongly suggested by SNO, Super Kamiokande, and similar experiments sensitive to delta m sup 2 , 0 nu beta beta-decay experiments are still the only way to establish the Dirac or Majorana nature of neutrinos by measuring effective electron neutrino mass, . Various theorists have recently argued in favor of a neutrino mass between 0.01 and 1 eV. The Majorana Project aims to probe this effective neutrino mass range, reaching a sensitivity of 0.02-0.07 eV. The experiment relies entirely on proven technology and has been devised based upon the materials, technology, and data analysis demonstrated to produce the lowest background per kilogram of fiducial germanium. The project plan includes 500 kg of germanium detector material enriched to 85% in sup 7 sup 6 Ge, specialized pulse-acquisition electronics and detector segmentation for background rejection, and underground electroformed ...
International Nuclear Information System (INIS)
Rybak, M.; Krygier, B.; Krempec-Krygier, J.
1985-01-01
The Hubble-Sandage diagrams for the Dirac cosmology have been discussed in the case of the modified dependence of luminosity upon the gravitational parameter G and mass. It is shown that the observational data for galaxies and the brightest quasars can be explained by the Dirac cosmology with the reasonably chosen changes of the gravitational parameter and of mass with the time. 41 refs., 2 figs. (author)
International Nuclear Information System (INIS)
Lanou, R.E. Jr.
1982-01-01
A study is made of the requirements necessary for improvement in our knowledge of limits in mass and mixing parameters for neutrinos via oscillation phenomena at accelerators. It is concluded that increased neutrino event rate (flux x energy) at modest energy machines (e.g., AGS and LAMPF) is the single most important requirement. This will permit smaller E/L ratios and refinement of systematics
Neutrino Mixing and Masses from a Minimum Principle
Alonso, R; Isidori, G; Maiani, L
2013-01-01
We analyze the structure of quark and lepton mass matrices under the hypothesis that they are determined from a minimum principle applied to a generic potential invariant under the $\\left[SU(3)\\right]^5\\otimes \\mathcal O(3)$ flavor symmetry, acting on Standard Model fermions and right-handed neutrinos. Unlike the quark case, we show that hierarchical masses for charged leptons are naturally accompanied by degenerate Majorana neutrinos with one mixing angle close to maximal, a second potentially large, a third one necessarily small, and one maximal relative Majorana phase. Adding small perturbations the predicted structure for the neutrino mass matrix is in excellent agreement with present observations and could be tested in the near future via neutrino-less double beta decay and cosmological measurements. The generalization of these results to arbitrary sew-saw models is also discussed.
Flipped neutrino emissivity from strange matter
Energy Technology Data Exchange (ETDEWEB)
Goyal, A.; Dutta, S. (Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India))
1994-04-15
Energy loss due to wrong helicity sterile neutrinos through spin flip processes leads to rapid cooling of nascent neutron stars. The observed cooling of neutron stars associated with SN 1987A seems to preclude the existence of Dirac neutrinos with a mass in excess of 20 keV. Assuming that nuclear matter in the core of the neutron star undergoes a phase transition to quark matter leading to a strange star or a neutron star with a strange matter core, we examine the emission of flipped Dirac neutrinos for two dominant processes: quark-neutrino scattering [[ital q]+[nu][sub [minus
Lai, Kwang-Chang; Lee, Fei-Fan; Lee, Feng-Shiuh; Lin, Guey-Lin; Liu, Tsung-Che; Yang, Yi
2016-07-01
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(bar nu) + p → ν(bar nu) + p, and inverse beta decays (IBD), bar nue + p → n + e+, 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 bar nue flux with the bar nux (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.
International Nuclear Information System (INIS)
Lai, Kwang-Chang; Lee, Fei-Fan; Lee, Feng-Shiuh; Lin, Guey-Lin; Liu, Tsung-Che; Yang, Yi
2016-01-01
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_e+p→n+e"+, 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_e flux with the ν-bar_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.
Low scale gravity as the source of neutrino masses?
Energy Technology Data Exchange (ETDEWEB)
Berezinsky, Veniamin [INFN, Laboratori Nazionali del Gran Sasso, I-67010 Assergi, AQ (Italy); Narayan, Mohan [INFN, Laboratori Nazionali del Gran Sasso, I-67010 Assergi, AQ (Italy); Vissani, Francesco [INFN, Laboratori Nazionali del Gran Sasso, I-67010 Assergi, AQ (Italy)
2005-04-01
We address the question whether low-scale gravity alone can generate the neutrino mass matrix needed to accommodate the observed phenomenology. In low-scale gravity the neutrino mass matrix in the flavor basis is characterized by one parameter (the gravity scale M{sub X}) and by an exact or approximate flavor blindness (namely, all elements of the mass matrix are of comparable size). Neutrino masses and mixings are consistent with the observational data for certain values of the matrix elements, but only when the spectrum of mass is inverted or degenerate. For the latter type of spectra the parameter M{sub ee} probed in double beta experiments and the mass parameter probed by cosmology are close to existing upper limits.
Low scale gravity as the source of neutrino masses?
International Nuclear Information System (INIS)
Berezinsky, Veniamin; Narayan, Mohan; Vissani, Francesco
2005-01-01
We address the question whether low-scale gravity alone can generate the neutrino mass matrix needed to accommodate the observed phenomenology. In low-scale gravity the neutrino mass matrix in the flavor basis is characterized by one parameter (the gravity scale M X ) and by an exact or approximate flavor blindness (namely, all elements of the mass matrix are of comparable size). Neutrino masses and mixings are consistent with the observational data for certain values of the matrix elements, but only when the spectrum of mass is inverted or degenerate. For the latter type of spectra the parameter M ee probed in double beta experiments and the mass parameter probed by cosmology are close to existing upper limits
Energy Technology Data Exchange (ETDEWEB)
Chan, Yat-Long; Chu, M.C.; Xu, Jianyi [The Chinese University of Hong Kong, Department of Physics, Shatin (China); Tsui, Ka Ming [University of Tokyo, RCCN, ICRR, Kashiwa, Chiba (Japan); Wong, Chan Fai [Sun Yat-Sen University, Guangzhou (China)
2016-06-15
We derive the neutrino flavor transition probabilities with the neutrino treated as a wave packet. The decoherence and dispersion effects from the wave-packet treatment show up as damping and phase-shifting of the plane-wave neutrino oscillation patterns. If the energy uncertainty in the initial neutrino wave packet is larger than around 0.01 of the neutrino energy, the decoherence and dispersion effects would degrade the sensitivity of reactor neutrino experiments to mass hierarchy measurement to lower than 3 σ confidence level. (orig.)
Neutrino mass hierarchy and three-flavor spectral splits of supernova neutrinos
International Nuclear Information System (INIS)
Dasgupta, Basudeb; Mirizzi, Alessandro; Tomas, Ricard; Tamborra, Irene
2010-01-01
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.
Neutrino diffusion and mass ejection in protoneutron stars
International Nuclear Information System (INIS)
Almeida, L. G.; Rodrigues, H.; Portes, D. Jr.; Duarte, S. B.
2010-01-01
We discuss the mass ejection mechanism induced by diffusion of neutrino during the early stage of the protoneutron star cooling. A dynamical calculation is employed in order to determine the amount of matter ejected and the remnant compact object mass. An equation of state considering hadronic and quark phases for the stellar dense matter was used to solve the whole time evolution of the system during the cooling phase. The initial neutrino population was obtained by considering beta equilibrium in the dense stellar matter with confined neutrinos, in the very early period of the deleptonic stage of the nascent pulsar. For specified initial configurations of the protoneutron star, we solve numerically the set of equations of motion together with neutrino diffusion through the dense stellar medium.
Neutrino helicity reversal and fundamental symmetries
International Nuclear Information System (INIS)
Jentschura, U D; Wundt, B J
2014-01-01
A rather elusive helicity reversal occurs in a gedanken experiment in which a massive left-handed Dirac neutrino, traveling at a velocity u < c, is overtaken on a highway by a speeding vehicle (traveling at velocity v with u < v < c). Namely, after passing the neutrino, looking back, one would see a right-handed neutrino (which has never been observed in nature). The Lorentz-invariant mass of the right-handed neutrino is still the same as before the passing. The gedanken experiment thus implies the existence of right-handed, light neutrinos, which are not completely sterile. Furthermore, overtaking a bunch of massive right-handed Dirac neutrinos leads to gradual de-sterilization. We discuss the helicity reversal and the concomitant sterilization and de-sterilization mechanisms by way of an illustrative example calculation, with a special emphasis on massive Dirac and Majorana neutrinos. We contrast the formalism with a modified Dirac neutrino described by a Dirac equation with a pseudoscalar mass term proportional to the fifth current. (paper)
Resolving neutrino mass hierarchy from supernova (anti)neutrino-nucleus reactions
Vale, Deni; Paar, Nils
2015-10-01
Recently a hybrid method has been introduced to determine neutrino mass hierarchy by simultaneous measurements of detector responses induced by antineutrino and neutrino fluxes from accretion and cooling phase of type II supernova. The (anti)neutrino-nucleus cross sections for 12C, 16O, 56Fe and 208Pb are calculated in the framework of relativistic nuclear energy density functional and weak interaction Hamiltonian, while the cross sections for inelastic scattering on free protons in mineral oil and water, p (v¯e,e+)n are obtained using heavy-baryon chiral perturbation theory. The simulations of (anti)neutrino fluxes emitted from a proto-neutron star in a core-collapse supernova include collective and Mikheyev-Smirnov-Wolfenstein effects inside star. It is shown that simultaneous use of ve/v¯e detectors with different target material allow to determine the neutrino mass hierarchy from the ratios of ve/v¯e induced particle emissions. The hybrid method favors detectors with heavier target nuclei (208Pb) for the neutrino sector, while for antineutrinos the use of free protons in mineral oil and water is more appropriate.
Neutrino seesaw mechanism with texture zeros
International Nuclear Information System (INIS)
Liao, Jiajun; Marfatia, D.; Whisnant, K.
2015-01-01
In the context of the Type I seesaw mechanism, we carry out a systematic study of the constraints that result from zeros in both the Dirac and right-handed Majorana neutrino mass matrices. We find that most constraints can be expressed in the standard form with one or two element/cofactor zeros alone, while there are 9 classes of nonstandard constraints. We show that all the constraints are stable under one-loop renormalization group running from the lightest right-handed neutrino mass scale to the electroweak scale. We study the predictions of the nonstandard constraints for the lightest neutrino mass, Dirac CP phase and neutrinoless double beta decay.
Neutrino CP violation and sign of baryon asymmetry in the minimal seesaw model
Shimizu, Yusuke; Takagi, Kenta; Tanimoto, Morimitsu
2018-03-01
We discuss the correlation between the CP violating Dirac phase of the lepton mixing matrix and the cosmological baryon asymmetry based on the leptogenesis in the minimal seesaw model with two right-handed Majorana neutrinos and the trimaximal mixing for neutrino flavors. The sign of the CP violating Dirac phase at low energy is fixed by the observed cosmological baryon asymmetry since there is only one phase parameter in the model. According to the recent T2K and NOνA data of the CP violation, the Dirac neutrino mass matrix of our model is fixed only for the normal hierarchy of neutrino masses.
GUT and flavor models for neutrino masses and mixing
Meloni, Davide
2017-10-01
In the recent years experiments have established the existence of neutrino oscillations and most of the oscillation parameters have been measured with a good accuracy. However, in spite of many interesting ideas, no real illumination was sparked on the problem of flavor in the lepton sector. In this review, we discuss the state of the art of models for neutrino masses and mixings formulated in the context of flavor symmetries, with particular emphasis on the role played by grand unified gauge groups.
Sterile neutrinos as dark matter
International Nuclear Information System (INIS)
Dodelson, S.; Widrow, L.M.
1994-01-01
The simplest model that can accommodate a viable nonbaryonic dark matter candidate is the standard electroweak theory with the addition of right-handed (sterile) neutrinos. We consider a single generation of neutrinos with a Dirac mass μ and a Majorana mass M for the right-handed component. If M much-gt μ (standard hot dark matter corresponds to M=0), then sterile neutrinos are produced via oscillations in the early Universe with energy density independent of M. However, M is crucial in determining the large scale structure of the Universe; for M∼100 eV, sterile neutrinos make an excellent warm dark matter candidate
Energy Technology Data Exchange (ETDEWEB)
Rosado, A. [Universidad Autonoma de Puebla, Puebla (Mexico)
2001-04-01
Assuming that the neutrino is a massless left-handed Dirac particle, we show that the neutrino anapole moment and the neutrino charge radius satisfy the simple relation a{sub v} =(r{sup 2}{sub v}) /6, in the context of the Standard Model of the electroweak interactions. We also show that the neutrino electroweak anapole moment a{sub v}l{sup E}W and the neutrino electroweak charge radius (r{sup 2}{sub v}){sup E}W, which have been defined through the v{sub l}l' scattering at the one-loop level and are physical quantities, also obey the relation a{sub v}l{sup E}W =(r{sup 2}{sub v}){sup E}W/6. [Spanish] Suponiendo que el neutrino es una particula de Dirac, sin masa y con helicidad izquierda, mostramos que el momento anapolar a{sub v} y el radio de carga (r{sub v}{sup 2}) del neutrino satisfacen la relacion simple a{sub v} =(r{sup 2}{sub v}) /6, en el contexto del Modelo Estandar de las interacciones electrodebiles. Ademas, mostramos que el momento anapolar electrodebil a{sub v}l{sup E}W y el radio de carga electrodebil (r{sup 2}{sub v}){sup E}W del neutrino, los cuales han sido definidos a traves de la dispersion v{sub l}l' a nivel de un lazo y que son cantidades fisicas, tambien obedecen la relacion a{sub v}l{sup E}W =(r{sup 2}{sub v}){sup E}W/6.
International Nuclear Information System (INIS)
Lobashev, V.M.; Aseev, V.N.; Belesev, A.I.; Berlev, A.I.; Geraskin, E.V.; Golubev, A.A.; Kazachenko, O.V.; Kuznetsov, Yu.E.; Ostroumov, R.P.; Rivkis, L.A.; Stern, B.E.; Titov, N.A.; Zadoroghny, C.V.; Zakharov, Yu.I.
2000-01-01
Results of the 'Troitsk ν-mass' experiment on search for the neutrino rest mass in the tritium beta-decay are presented. New data on the time dependence of the anomalous, bump-like structure at the end of the beta spectrum reported earlier are discussed. Possible systematics is considered in view of contradiction of 'Troitsk nu-mass' observation with those of 'Mainz neutrino' set-up. An upper limit for electron antineutrino rest mass remains at m ν 2 at 95% C.L
Experimental studies of neutrino oscillations
Kajita, Takaaki
2016-01-01
The 2015 Nobel Prize in physics has been awarded to Takaaki Kajita and Arthur McDonald "for the discovery of neutrino oscillations, which shows that neutrinos have mass". Takaaki Kajita of Tokyo University is a Japanese physicist, known for neutrino experiments at the Kamiokande and its successor, Super-Kamiokande. This volume of collected works of Kajita on neutrino oscillations provides a good glimpse into as well as a record of the rise and the role of Asian research in the frontiers of neutrino physics. Japan is now a major force in the study of the 3 families of neutrinos. Much remains to be done to clarify the Dirac vs. Majorana nature of the neutrino, and the cosmological implications of the neutrino. The collected works of Kajita and his Super-Kamiokande group will leave an indelible foot-print in the history of big and better science.
Flavor versus mass eigenstates in neutrino asymmetries: implications for cosmology
Energy Technology Data Exchange (ETDEWEB)
Barenboim, Gabriela [Universitat de Valencia-CSIC, Departament de Fisica Teorica y IFIC, Burjassot (Spain); Kinney, William H. [University at Buffalo, Department of Physics, Buffalo, NY (United States); Park, Wan-Il [Universitat de Valencia-CSIC, Departament de Fisica Teorica y IFIC, Burjassot (Spain); Chonbuk National University, Division of Science Education and Institute of Fusion Science, Jeonju (Korea, Republic of)
2017-09-15
We show that, if they exist, lepton number asymmetries (L{sub α}) of neutrino flavors should be distinguished from the ones (L{sub i}) of mass eigenstates, since Big Bang Nucleosynthesis (BBN) bounds on the flavor eigenstates cannot be directly applied to the mass eigenstates. Similarly, Cosmic Microwave Background (CMB) constraints on the mass eigenstates do not directly constrain flavor asymmetries. Due to the difference of mass and flavor eigenstates, the cosmological constraint on the asymmetries of neutrino flavors can be much stronger than the conventional expectation, but they are not uniquely determined unless at least the asymmetry of the heaviest neutrino is well constrained. The cosmological constraint on L{sub i} for a specific case is presented as an illustration. (orig.)
Neutrino mass ordering and μ-τ reflection symmetry breaking
Xing, Zhi-zhong; Zhu, Jing-yu
2017-12-01
If the neutrino mass spectrum turns out to be m 3case the columns of the 3×3 lepton flavor mixing matrix U should be reordered accordingly, and the resulting pattern U‧ may involve one or two large mixing angles in the standard parametrization or its variations. Since the Majorana neutrino mass matrix remains unchanged in such a mass relabeling, a possible μ-τ reflection symmetry is respected in this connection and its breaking effects are model-independently constrained at the 3σ level by using current experimental data. Supported by National Natural Science Foundation of China (11135009, 11375207)
A biased review of tau neutrino mass limits
Energy Technology Data Exchange (ETDEWEB)
Duboscq, J.E
2001-04-01
After a quick review of astrophysically relevant limits, I present a summary of MeV scale tau neutrino mass limits derived from accelerator based experiments. I argue that the current published limits appear to be too consistent, and that we therefore cannot conclude that the tau neutrino mass limit is as low as usually claimed. I provide motivational arguments calling into question the assumed statistical properties of the usual maximum likelihood estimators, and provide a prescription for deriving a more robust and understandable mass limit.
Neutrino mixing and masses in SO(10) GUTs with hidden sector and flavor symmetries
Energy Technology Data Exchange (ETDEWEB)
Chu, Xiaoyong [International Centre for Theoretical Physics,Strada Costiera 11, I-34100 Trieste (Italy); Smirnov, Alexei Yu. [Max-Planck-Institute for Nuclear Physics,Saupfercheckweg 1, D-69117 Heidelberg (Germany); International Centre for Theoretical Physics,Strada Costiera 11, I-34100 Trieste (Italy)
2016-05-23
We consider the neutrino masses and mixing in the framework of SO(10) GUTs with hidden sector consisting of fermionic and bosonic SO(10) singlets and flavor symmetries. The framework allows to disentangle the CKM physics responsible for the CKM mixing and different mass hierarchies of quarks and leptons and the neutrino new physics which produces smallness of neutrino masses and large lepton mixing. The framework leads naturally to the relation U{sub PMNS}∼V{sub CKM}{sup †}U{sub 0}, where structure of U{sub 0} is determined by the flavor symmetry. The key feature of the framework is that apart from the Dirac mass matrices m{sub D}, the portal mass matrix M{sub D} and the mass matrix of singlets M{sub S} are also involved in generation of the lepton mixing. This opens up new possibilities to realize the flavor symmetries and explain the data. Using A{sub 4}×Z{sub 4} as the flavor group, we systematically explore the flavor structures which can be obtained in this framework depending on field content and symmetry assignments. We formulate additional conditions which lead to U{sub 0}∼U{sub TBM} or U{sub BM}. They include (i) equality (in general, proportionality) of the singlet flavons couplings, (ii) equality of their VEVs; (iii) correlation between VEVs of singlets and triplet, (iv) certain VEV alignment of flavon triplet(s). These features can follow from additional symmetries or be remnants of further unification. Phenomenologically viable schemes with minimal flavon content and minimal number of couplings are constructed.
Neutrino mass hierarchy determination for θ13 = 0
International Nuclear Information System (INIS)
Gandhi, Raj; Ghoshal, Pomita; Goswami, Srubabati; Sankar, S. Uma
2010-01-01
We examine the possibility of determining the neutrino mass hierarchy in the limit θ 13 = 0 using atmospheric neutrinos as the source. In this limit, θ 13 driven matter effects are absent so independent measurements of Δ 31 and Δ 32 can, in principle, lead to hierarchy determination. Since their difference is Δ 21 , one needs an experimental arrangement where Δ 21 L/E > or approx. 1 can be achieved. This can be satisfied by atmospheric neutrinos which have a large range of L and E. Still, we find that hierarchy determination in the θ 13 = 0 limit with atmospheric neutrinos is not a realistic possibility, even in conjunction with a beam experiment like T2K or NOνA. We discuss why, and also reiterate the general conditions for hierarchy determination if θ 13 = 0.
Deconstructing the neutrino mass constraint from galaxy redshift surveys
Boyle, Aoife; Komatsu, Eiichiro
2018-03-01
The total mass of neutrinos can be constrained in a number of ways using galaxy redshift surveys. Massive neutrinos modify the expansion rate of the Universe, which can be measured using baryon acoustic oscillations (BAOs) or the Alcock-Paczynski (AP) test. Massive neutrinos also change the structure growth rate and the amplitude of the matter power spectrum, which can be measured using redshift-space distortions (RSD). We use the Fisher matrix formalism to disentangle these information sources, to provide projected neutrino mass constraints from each of these probes alone and to determine how sensitive each is to the assumed cosmological model. We isolate the distinctive effect of neutrino free-streaming on the matter power spectrum and structure growth rate as a signal unique to massive neutrinos that can provide the most robust constraints, which are relatively insensitive to extensions to the cosmological model beyond ΛCDM . We also provide forecasted constraints using all of the information contained in the observed galaxy power spectrum combined, and show that these maximally optimistic constraints are primarily limited by the accuracy to which the optical depth of the cosmic microwave background, τ, is known.
Shedding light on neutrino masses with dark forces
Energy Technology Data Exchange (ETDEWEB)
Batell, Brian [Pittsburgh Particle Physics, Astrophysics, and Cosmology Center,Department of Physics and Astronomy, University of Pittsburgh, PA 15260 (United States); Pospelov, Maxim [Perimeter Institute for Theoretical Physics,Waterloo, ON N2J 2W9 (Canada); Department of Physics and Astronomy, University of Victoria,Victoria, BC V8P 5C2 (Canada); Shuve, Brian [SLAC National Accelerator Laboratory,2575 Sand Hill Road, Menlo Park, CA 94025 (United States)
2016-08-08
Heavy right-handed neutrinos, N, provide the simplest explanation for the origin of light neutrino masses and mixings. If M{sub 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{sub B−L}→X+NN), 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.
Neutrino mass and the mirror universe
International Nuclear Information System (INIS)
Silagadze, Z.K.
1995-01-01
The existence of the mirror world, with the same microphysics as our own one but with opposite P-asymmetry, not only restores an exact equivalence between left and right, but provides a natural explanation via see-saw like mechanism why neutrino is massless (or ultralight). 28 refs
Models of neutrino masses and baryogenesis
Indian Academy of Sciences (India)
previous other indications of solar [2] and accelerator [3] neutrino oscillations ... baryon asymmetry of the universe before and during the electroweak phase ... The subject of baryogenesis originated when Sakharov [12] pointed out that ..... Whether a system is in equilibrium or not can be understood by solving the Boltzmann.
Flipped neutrino emissivity from strange matter
International Nuclear Information System (INIS)
Goyal, A.; Dutta, S.
1994-01-01
Energy loss due to wrong helicity sterile neutrinos through spin flip processes leads to rapid cooling of nascent neutron stars. The observed cooling of neutron stars associated with SN 1987A seems to preclude the existence of Dirac neutrinos with a mass in excess of 20 keV. Assuming that nuclear matter in the core of the neutron star undergoes a phase transition to quark matter leading to a strange star or a neutron star with a strange matter core, we examine the emission of flipped Dirac neutrinos for two dominant processes: quark-neutrino scattering [q+ν - (bar ν + )→q+ν + (bar ν - )] and the quark neutrino pair bremsstrahlung process [q+q→q+q+ν - bar ν - (ν+bar ν + )]. We determine the composition of quark matter just after core bounce and examine the effect of neutrino degeneracy on the emission rate and mean free path of the wrong helicity neutrinos
Neutrinos and the origin of fermion mass structure
International Nuclear Information System (INIS)
Ross, Graham G.
2007-01-01
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
An origin for small neutrino masses in the NMSSM
International Nuclear Information System (INIS)
Abada, Asmaa; Moreau, Gregory
2006-01-01
We consider the Next to Minimal Supersymmetric Standard Model (NMSSM) which provides a natural solution to the so-called μ problem by introducing a new gauge-singlet superfield S. We realize that a mechanism of neutrino mass suppression arises, based on the R-parity violating bilinear terms μ i L i H u mixing neutrinos and higgsinos, offering thus an original approach to the neutrino mass problem (connected to the solution for the μ problem). We generate realistic (Majorana) neutrino mass values without requiring any strong hierarchy amongst the fundamental parameters, in contrast with the alternative models. In particular, the ratio μ i /μ can reach ∼ 10 -1 , unlike in the MSSM where it has to be much smaller than unity. We check that the obtained parameters also satisfy the collider constraints and internal consistencies of the NMSSM. The price to pay for this new cancellation-type mechanism of neutrino mass reduction is a certain fine tuning, which get significantly improved in some regions of parameter space. Besides, we discuss the feasibility of our scenario when the R-parity violating bilinear terms have a common origin with the μ term, namely when those are generated via a VEV of the S scalar component from the couplings λ i SL i H u . Finally, we make comments on some specific phenomenology of the NMSSM in the presence of R-parity violating bilinear terms
Proposal on electron anti-neutrino mass measurement at INS
International Nuclear Information System (INIS)
Ohshima, Takayoshi.
1981-03-01
Some comment on the proposed experiment, namely the measurement of electron anti-neutrino mass, is described. Various experiments with the measurement of β-ray from tritium have been reported. The precise measurement of the shape of the Kurie plot is required in this kind of experiment. The present experiment aimed at more accurate determination of neutrino mass than any other previous ones. An important point of the present experiment is to reduce the background due to the β-ray from evaporating tritium. The source candidates have low evaporation rate. A double focus √2π air core spectrometer is employed for the measurement of β-ray. The spectrometer was improved to meet the present purpose. The accumulated event rate was expected to be about 10 times higher than Russian experiment. The estimated energy resolution was about 30 eV. The neutrino mass with less than 10 eV accuracy will be obtained. (Kato, T.)
Two old ways to measure the electron-neutrino mass
De Rújula, A
2013-01-01
Three decades ago, the measurement of the electron neutrino mass in atomic electron capture (EC) experiments was scrutinized in its two variants: single EC and neutrino-less double EC. For certain isotopes an atomic resonance enormously enhances the expected decay rates. The favoured technique, based on calorimeters as opposed to spectrometers, has the advantage of greatly simplifying the theoretical analysis of the data. After an initial surge of measurements, the EC approach did not seem to be competitive. But very recently, there has been great progress on micro-calorimeters and the measurement of atomic mass differences. Meanwhile, the beta-decay neutrino-mass limits have improved by a factor of 15, and the difficulty of the experiments by the cube of that figure. Can the "calorimetric" EC theory cope with this increased challenge? I answer this question affirmatively. In so doing I briefly review the subject and extensively address some persistent misunderstandings of the underlying quantum physics.
Direct bounds on the tau neutrino mass from LEP
International Nuclear Information System (INIS)
Passalacqua, L.
1996-11-01
A review of direct bounds on the mass of the tau neutrino obtained at the LEP collider is presented. In addition to published results it includes preliminary results presented at recent conferences and new results presented at the 1996 Tau Workshop. The different techniques and decay modes employed by the ALEPH, DELPHI and OPAL collaborations are compared. The impact of the theoretical modelling of tau decays is also discussed. The most stringent 95 % CL limit on the tau neutrino mass is now obtained by a preliminary ALEPH analysis which combines the results from τ → 5 π ± (π 0 ) v τ and τ → 3 π ± v τ decays. This bound constraints the mass of the tau neutrino below 18.2 M e V / c 2
Determining neutrino mass from the cosmic microwave background alone.
Kaplinghat, Manoj; Knox, Lloyd; Song, Yong-Seon
2003-12-12
Distortions of cosmic microwave background temperature and polarization maps caused by gravitational lensing, observable with high angular resolution and high sensitivity, can be used to measure the neutrino mass. Assuming two massless species and one with mass m(nu), we forecast sigma(m(nu))=0.15 eV from the Planck satellite and sigma(m(nu))=0.04 eV from observations with twice the angular resolution and approximately 20 times the sensitivity. A detection is likely at this higher sensitivity since the observation of atmospheric neutrino oscillations requires Deltam(2)(nu) greater, similar (0.04 eV)(2).
Cosmology in Mirror Twin Higgs and neutrino masses
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.
Constraining neutrino mass from neutrinoless double beta decay
Dev, P. S. Bhupal; Goswami, Srubabati; Mitra, Manimala; Rodejohann, Werner
2013-11-01
We study the implications of the recent results on neutrinoless double beta decay (0νββ) from GERDA-I (Ge76) and KamLAND-Zen+EXO-200 (Xe136) and the upper limit on the sum of light neutrino masses from Planck. We show that the upper limits on the effective neutrino mass from Xe136 are stronger than those from Ge76 for most of the recent calculations of the nuclear matrix elements (NMEs). We also analyze the compatibility of these limits with the claimed observation in Ge76 and show that while the updated claim value is still compatible with the recent GERDA limit as well as the individual Xe136 limits for a few NME calculations, it is inconsistent with the combined Xe136 limit for all but one NME. Imposing the most stringent limit from Planck, we find that the canonical light neutrino contribution cannot saturate the current limit, irrespective of the NME uncertainties. Saturation can be reached by inclusion of the right-handed (RH) neutrino contributions in TeV-scale left-right symmetric models with type-II seesaw. This imposes a lower limit on the lightest neutrino mass. Using the 0νββ bounds, we also derive correlated constraints in the RH sector, complimentary to those from direct searches at the LHC.
Neutrino Majorana masses from string theory instanton effects
International Nuclear Information System (INIS)
Ibanez, Luis E.; Uranga, Angel M.
2007-01-01
Finding a plausible origin for right-handed neutrino Majorana masses in semirealistic compactifications of string theory remains one of the most difficult problems in string phenomenology. We argue that right-handed neutrino Majorana masses are induced by non-perturbative instanton effects in certain classes of string compactifications in which the U(1) B-L gauge boson has a Stueckelberg mass. The induced operators are of the form e -U ν R ν R where U is a closed string modulus whose imaginary part transforms appropriately under B-L. This mass term may be quite large since this is not a gauge instanton and Re U is not directly related to SM gauge couplings. Thus the size of the induced right-handed neutrino masses could be a few orders of magnitude below the string scale, as phenomenologically required. It is also argued that this origin for neutrino masses would predict the existence of R-parity in SUSY versions of the SM. Finally we comment on other phenomenological applications of similar instanton effects, like the generation of a μ-term, or of Yukawa couplings forbidden in perturbation theory
Majorana neutrino transition magnetic moment in a variant of Zee model with horizontal symmetry
International Nuclear Information System (INIS)
Dhar, Jyoti; Dev, S.
1992-01-01
A SU(2) H symmetric variant of Zee model of lepton flavour violation is presented and is shown to lead to neutrino transition magnetic moment of the order required to explain the solar neutrino deficit and the possible anticorrelation of solar neutrino flux with sunspot activity via VVO mechanism. The use of horizontal symmetry leads to totally degenerate neutrino states which may be combined to form a ZKM Dirac neutrino with naturally small mass. (author). 22 refs., 1 fig
Reduced Dirac equation and Lamb shift as off-mass-shell effect in quantum electrodynamics
International Nuclear Information System (INIS)
Ni Guang-Jiong; Xu Jian-Jun; Lou Sen-Yue
2011-01-01
Based on the accurate experimental data of energy-level differences in hydrogen-like atoms, especially the 1S—2S transitions of hydrogen and deuterium, the necessity of introducing a reduced Dirac equation with reduced mass as the substitution of original electron mass is stressed. Based on new cognition about the essence of special relativity, we provide a reasonable argument for the reduced Dirac equation to have two symmetries, the invariance under the (newly defined) space-time inversion and that under the pure space inversion, in a noninertial frame. By using the reduced Dirac equation and within the framework of quantum electrodynamics in covariant form, the Lamb shift can be evaluated (at one-loop level) as the radiative correction on a bound electron staying in an off-mass-shell state—-a new approach eliminating the infrared divergence. Hence the whole calculation, though with limited accuracy, is simplified, getting rid of all divergences and free of ambiguity. (general)
Implications of neutrino masses and mixing for weak processes
International Nuclear Information System (INIS)
Shrock, R.E.
1981-01-01
A general theory is presented of weak processes involving neutrinos which consistently incorporates the possibility of nonzero neutrino masses and associated lepton mixing. The theory leads to new tests for and bounds on such masses and mixing. These tests make use of (π,K)/sub l2/ decay, nuclear β decay, and μ and tau decays, among others. New experiments at SIN and KEK to apply the tests are mentioned. Further, some implications are discussed for (1) the analysis of the spectral parameters in leptonic decays to determine the Lorentz structure of the weak leptonic couplings; (2) fundamental weak interaction constants such as G/sub μ/, G/sub V/', f/sub π/, f/sub K/, V/sub uq/, q = d or s, m/sub W/, and m/sub Z/; and (3) neutrino propagation
Determining neutrino mass hierarchy from electron disappearance at a low energy neutrino factory
International Nuclear Information System (INIS)
Raut, Sushant K.
2013-01-01
Reactor neutrino experiments have recently measured the value of θ 13 , to be non-zero and moderately large. This makes the determination of the neutrino mass hierarchy possible. However, our lack of knowledge of δ CP results in a parameter degeneracy, which makes this task difficult. The electron neutrino disappearance probability does not depend on δ CP . Therefore, in principle, it is possible to determine the hierarchy independently of δ CP using this channel. Previous studies of neutrino factories have not considered this channel, because the effect of systematics in electron disappearance is substantial. However, we show that for the moderately large value of θ 13 measured, hierarchy determination is possible in spite of systematic effects. We consider a low energy neutrino factory (LENF) setup with a totally active scintillator detector (TASD) with charge-identification. We optimize the setup in muon energy and baseline, for different allowed values of θ 13 and runtime. We find that a LENF with baseline of around 1300 km and muon energy around 3-4 GeV is well suited for hierarchy determination. For the RENO best-fit value of θ 13 , this setup can determine the hierarchy at 5ω, for all values of δ CP and for both hierarchies. (author)
Neutrino mass and physics beyond the Standard Model
International Nuclear Information System (INIS)
Hosteins, P.
2007-09-01
The purpose of this thesis is to study, in the neutrino sector, the flavour structures at high energy. The work is divided into two main parts. The first part is dedicated to the well known mechanism to produce small neutrino masses: the seesaw mechanism, which implies the existence of massive particles whose decays violate lepton number. Therefore this mechanism can also be used to generate a net baryon number in the early universe and explain the cosmological observation of the asymmetry between matter and antimatter. However, it is often non-trivial to fulfill the constraints coming at the same time from neutrino oscillations and cosmological experiments, at least in frameworks where the couplings can be somehow constrained, like some Grand Unification models. Therefore we devoted the first part to the study of a certain class of seesaw mechanism which can be found in the context of SO(10) theories for example. We introduce a method to extract the mass matrix of the heavy right-handed neutrinos and explore the phenomenological consequences of this quantity, mainly concerning the production of a sufficient baryon asymmetry. When trying to identify the underlying symmetry governing the mixings between the different generations, we see that there is a puzzling difference between the quark and the lepton sectors. However, the quark and lepton parameters have to be compared at the scale of the flavour symmetry breaking, therefore we have to make them run to the appropriate scale. Thus, it is worthwhile investigating models where quantum corrections allow an approximate unification of quark and lepton mixings. This is why the other part of the thesis investigates the running of the effective neutrino mass operator in models with an extra compact dimension, where quantum corrections to the neutrino masses and mixings can be potentially large due to the multiplicity of states
CP violation and neutrino masses and mixings from quark mass hierarchies
International Nuclear Information System (INIS)
Buchmueller, W.; Covi, L.; Emmanuel-Costa, D.; Wiesenfeldt, S.
2007-10-01
We study the connection between quark and lepton mass matrices in a supersymmetric SO(10) GUT model in six dimensions, compactified on an orbifold. The physical quarks and leptons are mixtures of brane and bulk states. This leads to a characteristic pattern of mass matrices and high-energy CP violating phases. The hierarchy of up and down quark masses determines the CKM matrix and most charged lepton and neutrino masses and mixings. The small hierarchy of neutrino masses is a consequence of the mismatch of the up and down quark mass hierarchies. The effective CP violating phases in the quark sector, neutrino oscillations and leptogenesis are unrelated. In the neutrino sector we can accomodate naturally sin θ 23 ∝1, sin θ 13 1 2 ∝√(Δm 2 sol ) 3 ∝√(Δm 2 atm ). (orig.)
CP violation and neutrino masses and mixings from quark mass hierarchies
International Nuclear Information System (INIS)
Buchmueller, Wilfried; Covi, Laura; Emmanuel-Costa, David; Wiesenfeldt, Soeren
2007-01-01
We study the connection between quark and lepton mass matrices in a supersymmetric SO(10) GUT model in six dimensions, compactified on an orbifold. The physical quarks and leptons are mixtures of brane and bulk states. This leads to a characteristic pattern of mass matrices and high-energy CP violating phases. The hierarchy of up and down quark masses determines the CKM matrix and most charged lepton and neutrino masses and mixings. The small hierarchy of neutrino masses is a consequence of the mismatch of the up and down quark mass hierarchies. The effective CP violating phases in the quark sector, neutrino oscillations and leptogenesis are unrelated. In the neutrino sector we can accomodate naturally sin θ 23 ∼ 1, sin θ 13 ∼ 1 ∼ 2 ∼ (Δm 2 sol ) 1/2 3 ∼ (Δm 2 atm ) 1/2
Determination of absolute neutrino masses from Z-bursts
International Nuclear Information System (INIS)
Fodor, Z.
2001-05-01
Ultrahigh energy neutrinos (UHEν) scatter on cosmological relic neutrinos (Rν) producing Z bosons, which can decay hadronically producing protons (Z-burst). We compare the predicted proton spectrum with the observed ultrahigh energy cosmic ray (UHECR) spectrum and determine the mass of the heaviest Rν via a maximum likelihood analysis. Our mass prediction depends on the origin of the power-like part of the UHECR spectrum: m ν = 2.34 -0.84 +1.29 eV for Galactic halo and 0.26 -0.14 +0.20 eV for extragalactic (EG) origin. The second mass, with a lower bound of 0.06 eV on the 95% confidence level (CL), is compatible with a hierarchical ν mass scenario with the largest mass suggested by the atmospheric ν oscillation. The necessary UHEν flux is compatible with present upper limits and should be detected in the near future. (orig.)
arXiv Neutrino Masses from Outer Space
D'Amico, Guido; Kaloper, Nemanja
Neutrinos can gain mass from coupling to an ultralight field in slow roll. When such a field is displaced from its minimum, its vev acts just like the Higgs vev in spontaneous symmetry breaking. Although these masses may eventually vanish, they do it over a very long time. The theory is technically natural, with the ultralight field-dependent part being the right-handed Majorana mass. The mass variation induced by the field correlates with the cosmological evolution. The change of the mass term changes the mixing matrix, and therefore suppresses the fraction of sterile neutrinos at earlier times and increases it at later times. Since the issue of quantum gravity corrections to field theories with large field variations remains open, this framework may give an observational handle on the Weak Gravity Conjecture.
Introductory talk. 6. Moriond workshop massive neutrinos in particle physics and astrophysics
International Nuclear Information System (INIS)
Rosen, S.P.
1986-01-01
We review the concepts of Majorana and Dirac neutrinos from an operational point of view and survey the experimental search for neutrino mass. We also review the work of Mikheyev and Smirnov on the enhancement of neutrino oscillations via the mechanism of Wolfenstein matter oscillations. Results of an extensive computation of MSW effects in the sun are described. 39 refs., 6 figs
Common Origin of Neutrino Mass, Dark Matter, and Baryogenesis
Ma, Ernest
2006-01-01
Combining one established idea with two recent ones, it is pointed out for the first time that three of the outstanding problems of particle physics and cosmology, i.e. neutrino mass, dark matter, and baryogenesis, may have a common solution, arising from the interactions of a single term, with experimentally verifiable consequences.
Neutrino masses and the unification of the SO(10) families
International Nuclear Information System (INIS)
Maalampi, J.; Enqvist, K.
1980-01-01
We show that the unification of the SO(10) families in SO(10+m) group can offer a solution to the neutrino mass problem. For simplicity we have restricted our analysis to SO(11), which contains - aside from generation mixing -the main novel feature of the theories of this kind: fermions that couple by V+A charged weak currents. (author)
A common source for neutrino and sparticle masses
Brignole, Andrea; Rossi, Anna
2010-01-01
We discuss supersymmetric scenarios in which neutrino masses arise from effective d=6 operators in the Kahler potential (including SUSY-breaking insertions). Simple explicit realizations of those Kahler operators are presented in the context of the type II seesaw. An appealing scenario emerges upon identifying the seesaw mediators with SUSY-breaking messengers.
Renormalization of seesaw neutrino masses in the standard model ...
Indian Academy of Sciences (India)
the neutrino-mass-operator in the standard model with two-Higgs doublets, and also the QCD–QED ... data of atmospheric muon deficits, thereby suggesting a large mixing angle with ЖС¾. Ь ~ ... One method consists of running the gauge.
Most recent results of the Mainz Neutrino Mass Espetiment
Czech Academy of Sciences Publication Activity Database
Kraus, Ch.; Bornschein, L.; Bonn, J.; Bornschein, B.; Conde, F.; Flatt, B.; Kovalík, Alojz; Müller, B.; Otten, E.; Schall, J.; Thümmler, Th.; Weinheimer, Ch.
2003-01-01
Roč. 118, - (2003), s. 482 ISSN 0920-5632 R&D Projects: GA ČR GA202/02/0157 Institutional research plan: CEZ:AV0Z1048901 Keywords : beta-spectrum * neutrino mass Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.990, year: 2003
Neutrino mass | Nduka | Journal of the Nigerian Association of ...
African Journals Online (AJOL)
It turns out that geometrization of matter is a necessary prerequisite for the resolution of many problems of considerable current interest. In this paper we discuss the geometrization of matter, and deduce therefore the mass of the neutrino. Journal of the Nigerian Association of Mathematical Physics Vol. 10 2006: pp. 1-4 ...
A three-parameter neutrino mass matrix with maximal CP violation
International Nuclear Information System (INIS)
Grimus, W.; Lavoura, L.
2009-01-01
Using the seesaw mechanism, we construct a model for the light-neutrino Majorana mass matrix which yields trimaximal lepton mixing together with maximal CP violation and maximal atmospheric-neutrino mixing. We demonstrate that, in our model, the light-neutrino mass matrix retains its form under the one-loop renormalization-group evolution. With our neutrino mass matrix, the absolute neutrino mass scale is a function of |U e3 | and of the atmospheric mass-squared difference. We study the effective mass in neutrinoless ββ decay as a function of |U e3 |, showing that it contains a fourfold ambiguity
The Use of Low Temperature Detectors for Direct Measurements of the Mass of the Electron Neutrino
Directory of Open Access Journals (Sweden)
A. Nucciotti
2016-01-01
Full Text Available Recent years have witnessed many exciting breakthroughs in neutrino physics. The detection of neutrino oscillations has proved that neutrinos are massive particles, but the assessment of their absolute mass scale is still an outstanding challenge in today particle physics and cosmology. Since low temperature detectors were first proposed for neutrino physics experiments in 1984, there has been tremendous technical progress: today this technique offers the high energy resolution and scalability required to perform competitive experiments challenging the lowest electron neutrino masses. This paper reviews the thirty-year effort aimed at realizing calorimetric measurements with sub-eV neutrino mass sensitivity using low temperature detectors.
Energy Technology Data Exchange (ETDEWEB)
Hosteins, P
2007-09-15
The purpose of this thesis is to study, in the neutrino sector, the flavour structures at high energy. The work is divided into two main parts. The first part is dedicated to the well known mechanism to produce small neutrino masses: the seesaw mechanism, which implies the existence of massive particles whose decays violate lepton number. Therefore this mechanism can also be used to generate a net baryon number in the early universe and explain the cosmological observation of the asymmetry between matter and antimatter. However, it is often non-trivial to fulfill the constraints coming at the same time from neutrino oscillations and cosmological experiments, at least in frameworks where the couplings can be somehow constrained, like some Grand Unification models. Therefore we devoted the first part to the study of a certain class of seesaw mechanism which can be found in the context of SO(10) theories for example. We introduce a method to extract the mass matrix of the heavy right-handed neutrinos and explore the phenomenological consequences of this quantity, mainly concerning the production of a sufficient baryon asymmetry. When trying to identify the underlying symmetry governing the mixings between the different generations, we see that there is a puzzling difference between the quark and the lepton sectors. However, the quark and lepton parameters have to be compared at the scale of the flavour symmetry breaking, therefore we have to make them run to the appropriate scale. Thus, it is worthwhile investigating models where quantum corrections allow an approximate unification of quark and lepton mixings. This is why the other part of the thesis investigates the running of the effective neutrino mass operator in models with an extra compact dimension, where quantum corrections to the neutrino masses and mixings can be potentially large due to the multiplicity of states.
PINGU and the neutrino mass hierarchy: Statistical and systematical aspects
International Nuclear Information System (INIS)
Capozzi, F.; Marrone, A.; Lisi, E.
2016-01-01
The proposed PINGU project (Precision IceCube Next Generation Upgrade) is supposed to determine neutrino mass hierarchy through matter effects of atmospheric neutrinos crossing the Earth core and mantle, which leads to variations in the events spectrum in energy and zenith angle. The presence of non-negligible (and partly unknown) systematics on the spectral shape can make the statistical analysis particularly challenging in the limit of high statistics. Assuming plausible spectral shape uncertainties at the percent level (due to effective volume, cross section, resolution functions, oscillation parameters, etc.), we obtain a significant reduction in the sensitivity to the hierarchy. The obtained results show the importance of a dedicated research program aimed at a better characterization and reduction of the uncertainties in future high-statistics experiments with atmospheric neutrinos.
Possibility of experimental detection of the Dirac-Schwinger heavy mass monopoles
Energy Technology Data Exchange (ETDEWEB)
Ginzburg, I F [AN SSSR, Novosibirsk. Inst. Matematiki; Panfil, S L [AN SSSR, Novosibirsk. Inst. Avtomatiki i Ehlektrometrii
1982-12-01
A possibility of the Dirac-Schwinger point heavy-mass monopoles detection in scattering or production of photons at large angles via the monopole loop, is discussed. The monopoles with masses M < or approximately from 50 to 100 GeV may be found in experiments at PETRA and PEP, and monopoles with masses M < or approximately from 2 to 3 TeV may be discovered in future experiments in colliding photon beams of 50-300 GeV energies.
Predicting {theta}{sub 13} and the neutrino mass scale from quark lepton mass hierarchies
Energy Technology Data Exchange (ETDEWEB)
Buchmueller, W.; Domcke, V.; Schmitz, K.
2011-11-15
Flavour symmetries of Froggatt-Nielsen type can naturally reconcile the large quark and charged lepton mass hierarchies and the small quark mixing angles with the observed small neutrino mass hierarchies and their large mixing angles. We point out that such a flavour structure, together with the measured neutrino mass squared differences and mixing angles, strongly constrains yet undetermined parameters of the neutrino sector. Treating unknown O(1) parameters as random variables, we obtain surprisingly accurate predictions for the smallest mixing angle, sin{sup 2}2{theta}{sub 13}=0.07{sup +0.11}{sub -0.05}, the smallest neutrino mass, m{sub 1}=2.5{sup +1.7}{sub -1.6} x 10{sup -3} eV, and one Majorana phase, {alpha}{sub 21}/{pi}=1.0{sup +0.2}{sub -0.2}. (orig.)
Model independent bounds on magnetic moments of Majorana neutrinos
International Nuclear Information System (INIS)
Bell, Nicole F.; Gorchtein, Mikhail; Ramsey-Musolf, Michael J.; Vogel, Petr; Wang, Peng
2006-01-01
We analyze the implications of neutrino masses for the magnitude of neutrino magnetic moments. By considering electroweak radiative corrections to the neutrino mass, we derive model-independent naturalness upper bounds on neutrino magnetic moments, μ ν , generated by physics above the electroweak scale. For Dirac neutrinos, the bound is several orders of magnitude more stringent than present experimental limits. However, for Majorana neutrinos the magnetic moment contribution to the mass is Yukawa suppressed. The bounds we derive for magnetic moments of Majorana neutrinos are weaker than present experimental limits if μ ν is generated by new physics at ∼1 TeV, and surpass current experimental sensitivity only for new physics scales >10-100 TeV. The discovery of a neutrino magnetic moment near present limits would thus signify that neutrinos are Majorana particles
Neutrino mass, dark energy, and the linear growth factor
International Nuclear Information System (INIS)
Kiakotou, Angeliki; Lahav, Ofer; Elgaroey, Oystein
2008-01-01
We study the degeneracies between neutrino mass and dark energy as they manifest themselves in cosmological observations. In contradiction to a popular formula in the literature, the suppression of the matter power spectrum caused by massive neutrinos is not just a function of the ratio of neutrino to total mass densities f ν =Ω ν /Ω m , but also each of the densities independently. We also present a fitting formula for the logarithmic growth factor of perturbations in a flat universe, f(z,k;f ν ,w,Ω DE )≅[1-A(k)Ω DE f ν +B(k)f ν 2 -C(k)f ν 3 ]Ω m α (z), where α depends on the dark energy equation of state parameter w. We then discuss cosmological probes where the f factor directly appears: peculiar velocities, redshift distortion, and the integrated Sachs-Wolfe effect. We also modify the approximation of Eisenstein and Hu [Astrophys. J. 511, 5 (1999)] for the power spectrum of fluctuations in the presence of massive neutrinos and provide a revised code [http://www.star.ucl.ac.uk/∼lahav/nu m atter p ower.f].
Neutrino mass with large S U (2 )L multiplet fields
Nomura, Takaaki; Okada, Hiroshi
2017-11-01
We propose an extension of the standard model introducing large S U (2 )L multiplet fields which are quartet and septet scalars and quintet Majorana fermions. These multiplets can induce the neutrino masses via interactions with the S U (2 ) doublet leptons. We then find the neutrino masses are suppressed by a small vacuum expectation value of the quartet/septet and an inverse of the quintet fermion mass, relaxing the Yukawa hierarchies among the standard model fermions. We also discuss collider physics at the Large Hadron Collider, considering the production of charged particles in these multiplets, and due to the effects of violating the custodial symmetry, some specific signatures can be found. Then, we discuss the detectability of these signals.
Quark mass anomalous dimension from the twisted mass Dirac operator spectrum
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics
2013-12-15
We investigate whether it is possible to extract the quark mass anomalous dimension and its scale dependence from the spectrum of the twisted mass Dirac operator in Lattice QCD. The answer to this question appears to be positive, provided that one goes to large enough eigenvalues, sufficiently above the non-perturbative regime. The obtained results are compared to continuum perturbation theory. By analyzing possible sources of systematic effects, we find the domain of applicability of the approach, extending from an energy scale of around 1.5 to 4 GeV. The lower limit is dictated by physics (non-perturbative effects at low energies), while the upper bound is set by the ultraviolet cut-off of present-day lattice simulations. We use gauge field configuration ensembles generated by the European Twisted Mass Collaboration (ETMC) with 2 flavours of dynamical twisted mass quarks, at 4 lattice spacings in the range between around 0.04 and 0.08 fm.
Quark mass anomalous dimension from the twisted mass Dirac operator spectrum
International Nuclear Information System (INIS)
Cichy, Krzysztof; Poznan Univ.
2013-12-01
We investigate whether it is possible to extract the quark mass anomalous dimension and its scale dependence from the spectrum of the twisted mass Dirac operator in Lattice QCD. The answer to this question appears to be positive, provided that one goes to large enough eigenvalues, sufficiently above the non-perturbative regime. The obtained results are compared to continuum perturbation theory. By analyzing possible sources of systematic effects, we find the domain of applicability of the approach, extending from an energy scale of around 1.5 to 4 GeV. The lower limit is dictated by physics (non-perturbative effects at low energies), while the upper bound is set by the ultraviolet cut-off of present-day lattice simulations. We use gauge field configuration ensembles generated by the European Twisted Mass Collaboration (ETMC) with 2 flavours of dynamical twisted mass quarks, at 4 lattice spacings in the range between around 0.04 and 0.08 fm.
Models of neutrino masses: Anarchy versus hierarchy
International Nuclear Information System (INIS)
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)xU(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. (author)
Born–Infeld condensate as a possible origin of neutrino masses and dark energy
Energy Technology Data Exchange (ETDEWEB)
Addazi, Andrea [Dipartimento di Fisica, Università di L' Aquila, 67010 Coppito AQ (Italy); Laboratori Nazionali del Gran Sasso (INFN), 67010 Assergi AQ (Italy); Capozziello, Salvatore [Dipartimento di Fisica “Ettore Pancini”, Università di Napoli “Federico II”, INFN Sez. di Napoli, Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, I-80126, Napoli (Italy); INFN Sez. di Napoli, Compl. Univ. di Monte S. Angelo, Edificio G, Via Cinthia, I-80126, Napoli (Italy); Gran Sasso Science Institute (INFN), Viale F. Crispi 7, I-67100, L' Aquila (Italy); Odintsov, Sergei [Institució Catalana de Recerca i Estudis Avancats (ICREA), Barcelona (Spain); Institut de Ciencies de l' Espai (IEEC-CSIC), Campus UAB, Carrer de Can Magrans, s/n 08193 Cerdanyola del Valles, Barcelona (Spain); Lab. Theor. Cosmology, Tomsk State University of Control Systems and Radioelectronics (TUSUR), 634050 Tomsk (Russian Federation); Tomsk State Pedagogical University, 634061 Tomsk (Russian Federation)
2016-09-10
We discuss the possibility that a Born–Infeld condensate coupled to neutrinos can generate both neutrino masses and an effective cosmological constant. In particular, an effective field theory is provided capable of dynamically realizing the neutrino superfluid phase firstly suggested by Ginzburg and Zharkov. In such a case, neutrinos acquire a mass gap inside the Born–Infeld ether forming a long-range Cooper pair. Phenomenological implications of the approach are also discussed.
Hadron collider tests of neutrino mass-generating mechanisms
Ruiz, Richard Efrain
The Standard Model of particle physics (SM) is presently the best description of nature at small distances and high energies. However, with tiny but nonzero neutrino masses, a Higgs boson mass unstable under radiative corrections, and little guidance on understanding the hierarchy of fermion masses, the SM remains an unsatisfactory description of nature. Well-motivated scenarios that resolve these issues exist but also predict extended gauge (e.g., Left-Right Symmetric Models), scalar (e.g., Supersymmetry), and/or fermion sectors (e.g., Seesaw Models). Hence, discovering such new states would have far-reaching implications. After reviewing basic tenets of the SM and collider physics, several beyond the SM (BSM) scenarios that alleviate these shortcomings are investigated. Emphasis is placed on the production of a heavy Majorana neutrinos at hadron colliders in the context of low-energy, effective theories that simultaneously explain the origin of neutrino masses and their smallness compared to other elementary fermions, the so-called Seesaw Mechanisms. As probes of new physics, rare top quark decays to Higgs bosons in the context of the SM, the Types I and II Two Higgs Doublet Model (2HDM), and the semi-model independent framework of Effective Field Theory (EFT) have also been investigated. Observation prospects and discovery potentials of these models at current and future collider experiments are quantified.
Viability of Dirac phase leptogenesis
International Nuclear Information System (INIS)
Anisimov, Alexey; Blanchet, Steve; Di Bari, Pasquale
2008-01-01
We discuss the conditions for a non-vanishing Dirac phase δ and mixing angle θ 13 , sources of CP violation in neutrino oscillations, to be uniquely responsible for the observed matter–antimatter asymmetry of the Universe through leptogenesis. We show that this scenario, that we call δ-leptogenesis, is viable when the degenerate limit for the heavy right-handed (RH) neutrino spectrum is considered. We derive an interesting joint condition on sinθ 13 and the absolute neutrino mass scale that can be tested in future neutrino oscillation experiments. In the limit of the hierarchical heavy RH neutrino spectrum, we strengthen the previous result that δ-leptogenesis is only very marginally allowed, even when the production from the two heavier RH neutrinos is taken into account. An improved experimental upper bound on sinθ 13 and/or an account of quantum kinetic effects could completely rule out this option in the future. Therefore, δ-leptogenesis can be also regarded as motivation for models with degenerate heavy neutrino spectrum
Generalized one-loop neutrino mass model with charged particles
Cheung, Kingman; Okada, Hiroshi
2018-04-01
We propose a radiative neutrino-mass model by introducing 3 generations of fermion pairs E-(N +1 )/2E+(N +1 )/2 and a couple of multicharged bosonic doublet fields ΦN /2,ΦN /2 +1, where N =1 , 3, 5, 7, 9. We show that the models can satisfy the neutrino masses and oscillation data, and are consistent with lepton-flavor violations, the muon anomalous magnetic moment, the oblique parameters, and the beta function of the U (1 )Y hypercharge gauge coupling. We also discuss the collider signals for various N , namely, multicharged leptons in the final state from the Drell-Yan production of E-(N +1 )/2E+(N +1 )/2. In general, the larger the N the more charged leptons will appear in the final state.
Energy Technology Data Exchange (ETDEWEB)
Lai, Kwang-Chang [Center for General Education, Chang Gung University,Kwei-Shan, Taoyuan, 333, Taiwan (China); Leung Center for Cosmology and Particle Astrophysics (LeCosPA), National Taiwan University, Taipei, 106, Taiwan (China); Lee, Fei-Fan [Institute of Physics, National Chiao Tung University,Hsinchu, 300, Taiwan (China); Lee, Feng-Shiuh [Department of Electrophysics, National Chiao Tung University,Hsinchu, 300, Taiwan (China); Lin, Guey-Lin [Leung Center for Cosmology and Particle Astrophysics (LeCosPA), National Taiwan University, Taipei, 106, Taiwan (China); Institute of Physics, National Chiao Tung University,Hsinchu, 300, Taiwan (China); Liu, Tsung-Che [Leung Center for Cosmology and Particle Astrophysics (LeCosPA), National Taiwan University, Taipei, 106, Taiwan (China); Yang, Yi [Department of Electrophysics, National Chiao Tung University,Hsinchu, 300, Taiwan (China)
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.
International Nuclear Information System (INIS)
Dermisek, Radovan
2004-01-01
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 θ 13 . 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 (m top 2 /M GUT )sin 2 θ 23 sin 2 θ 12 in the limit sin θ 13 ≅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, M 1 ,M 2 -4 M 3 , M 3 =M GUT
Seesaw neutrino masses with large mixings from dimensional deconstruction
International Nuclear Information System (INIS)
Balaji, K.R.S.; Lindner, Manfred; Seidl, Gerhart
2003-01-01
We demonstrate a dynamical origin for the dimension-five seesaw operator in dimensional deconstruction models. Light neutrino masses arise from the seesaw scale which corresponds to the inverse lattice spacing. It is shown that the deconstructing limit naturally prefers maximal leptonic mixing. Higher-order corrections which are allowed by gauge invariance can transform the bimaximal into a bilarge mixing. These terms may appear to be nonrenormalizable at scales smaller than the deconstruction scale
The neutrino mass from beta spectrum (ITEP-85)
International Nuclear Information System (INIS)
Lubimov, V.
1986-01-01
The new cycle of tritium beta spectrum measurements in valine with the ITEP spectrometer is discussed (ITEP-85). The detailed investigation of the total response function (TRF) has been performed. The special run of beta spectrum measurements carried out in a wide energy interval (3.4 KeV) has turned out to be a sensitive mode for the TRF experimental test. The results confirm the indication of the neutrino nonzero mass. 11 refs., 10 figs
Late time neutrino masses, the LSND experiment, and the cosmic microwave background.
Chacko, Z; Hall, Lawrence J; Oliver, Steven J; Perelstein, Maxim
2005-03-25
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 Liquid Scintillator Neutrino Detector experiment. Furthermore, the constraints on the sterile neutrino properties from nucleosynthesis and large-scale structure can be removed due to the nonconventional 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.
Common Origin for Neutrino Anarchy and Charged Hierarchies
International Nuclear Information System (INIS)
Agashe, Kaustubh; Okui, Takemichi; Sundrum, Raman
2009-01-01
The generation of exponential flavor hierarchies from extra-dimensional wave function overlaps is reexamined. We find, surprisingly, that the coexistence of anarchic fermion mass matrices with such hierarchies is intrinsic and natural to this setting. The salient features of charged fermion and neutrino masses and mixings can thereby be captured within a single framework. Both Dirac and Majorana neutrinos can be realized. Implications for a variety of weak-scale scenarios, including warped compactification and supersymmetry, are discussed. When the new weak-scale physics is sensitive to the origin of flavor structure, Dirac neutrinos are preferred
International Nuclear Information System (INIS)
Hagedorn, Claudia; Schmidt, Michael A.; Smirnov, Alexei Yu.
2009-01-01
In SO(10) grand unified theories the hierarchy which is present in the Dirac mass term of the neutrinos is generically as strong as the one in the up-type quark mass term. We propose a mechanism to partially or completely cancel this hierarchy in the light neutrino mass matrix in the seesaw context. The two main ingredients of the cancellation mechanism are the existence of three fermionic gauge singlets and of a discrete flavor symmetry G f which is broken at a higher scale than SO(10). Two realizations of the cancellation mechanism are presented. The realization based on the Frobenius group T 7 ≅Z 7 xZ 3 leads to a partial cancellation of the hierarchy and relates maximal 2-3 lepton mixing with the geometric hierarchy of the up-quark masses. In the realization with the group Σ(81) the cancellation is complete and tribimaximal lepton mixing is reproduced at the lowest order. In both cases, to fully accommodate the leptonic data we take into account additional effects such as effects of higher-dimensional operators involving more than one flavon. The heavy neutral fermion mass spectra are considered. For both realizations we analyze the flavon potential at the renormalizable level as well as ways to generate the Cabibbo angle.
Radiatively induced neutrino mass model with flavor dependent gauge symmetry
Lee, SangJong; Nomura, Takaaki; Okada, Hiroshi
2018-06-01
We study a radiative seesaw model at one-loop level with a flavor dependent gauge symmetry U(1) μ - τ, in which we consider bosonic dark matter. We also analyze the constraints from lepton flavor violations, muon g - 2, relic density of dark matter, and collider physics, and carry out numerical analysis to search for allowed parameter region which satisfy all the constraints and to investigate some predictions. Furthermore we find that a simple but adhoc hypothesis induces specific two zero texture with inverse mass matrix, which provides us several predictions such as a specific pattern of Dirac CP phase.
Peccei-Quinn symmetry for Dirac seesaw and leptogenesis
Energy Technology Data Exchange (ETDEWEB)
Gu, Pei-Hong [Department of Physics and Astronomy, Shanghai Jiao Tong University,800 Dongchuan Road, Shanghai 200240 (China)
2016-07-04
We extend the DFSZ invisible axion model to simultaneously explain small Dirac neutrino masses and cosmic matter-antimatter asymmetry. After the Peccei-Quinn and electroweak symmetry breaking, the effective Yukawa couplings of the Dirac neutrinos to the standard model Higgs scalar can be highly suppressed by the ratio of the vacuum expectation value of an iso-triplet Higgs scalar over the masses of some heavy gauge-singlet fermions, iso-doublet Higgs scalars or iso-triplet fermions. The iso-triplet fields can carry a zero or nonzero hypercharge. Through the decays of the heavy gauge-singlet fermions, iso-doublet scalars or iso-triplet fermions, we can obtain a lepton asymmetry in the left-handed leptons and an opposite lepton asymmetry in the right-handed neutrinos. Since the right-handed neutrinos do not participate in the sphaleron processes, the left-handed lepton asymmetry can be partially converted to a baryon asymmetry.
With neutrino masses revealed, proton decay is the missing link
International Nuclear Information System (INIS)
Pati, J.C.
1999-01-01
By way of paying tribute to Abdus Salam, I recall the ideas of higher unification that he and I initiated. I discuss the current status of those ideas in the light of recent developments, including those of: (a) gauge coupling unification, (b) discovery of neutrino-oscillation at SuperKamiokande, and (c) ongoing searches for proton decay. It is noted that the mass of ν τ (∼ 1/20 eV), suggested by the SuperK result, provides clear support for the route to higher unification based on the ideas of (i) SU(4)-color, (ii) left-right symmetry and (iii) supersymmetry. The change in perspective, pertaining to both gauge coupling unification and proton decay, brought forth by supersymmetry and superstrings, is noted. And, the beneficial roles of string-symmetries in addressing certain naturalness problems of supersymmetry, including that of rapid proton decay, are emphasized. Further, it is noted that with neutrino masses and coupling unification revealed, proton decay is the missing link. Following recent joint work with K. Babu and F. Wilczek, based on supersymmetric unification, it is remarked that the SuperKamiokande result on neutrino oscillation in fact enhances the expected rate of proton decay compared to prior estimates. Thus, assuming supersymmetric unification, one expects that the discovery of proton decay should not be far behind. (author)
Majorana neutrino masses and the neutrinoless double-beta decay
International Nuclear Information System (INIS)
Faessler, A.
2006-01-01
Neutrinoless double-beta decay is forbidden in the Standard Model of electroweak and strong interaction but allowed in most Grand Unified Theories (GUTs). Only if the neutrino is a Majorana particle (identical with its antiparticle) and if it has a mass is neutrinoless double-beta decay allowed. Apart from one claim that the neutrinoless double-beta decay in 76 Ge is measured, one has only upper limits for this transition probability. But even the upper limits allow one to give upper limits for the electron Majorana neutrino mass and upper limits for parameters of GUTs and the minimal R-parity-violating supersymmetric model. One further can give lower limits for the vector boson mediating mainly the right-handed weak interaction and the heavy mainly right-handed Majorana neutrino in left-right symmetric GUTs. For that, one has to assume that the specific mechanism is the leading one for neutrinoless double-beta decay and one has to be able to calculate reliably the corresponding nuclear matrix elements. In the present work, one discusses the accuracy of the present status of calculating of the nuclear matrix elements and the corresponding limits of GUTs and supersymmetric parameters
Measurement of collective dynamical mass of Dirac fermions in graphene.
Yoon, Hosang; Forsythe, Carlos; Wang, Lei; Tombros, Nikolaos; Watanabe, Kenji; Taniguchi, Takashi; Hone, James; Kim, Philip; Ham, Donhee
2014-08-01
Individual electrons in graphene behave as massless quasiparticles. Unexpectedly, it is inferred from plasmonic investigations that electrons in graphene must exhibit a non-zero mass when collectively excited. The inertial acceleration of the electron collective mass is essential to explain the behaviour of plasmons in this material, and may be directly measured by accelerating it with a time-varying voltage and quantifying the phase delay of the resulting current. This voltage-current phase relation would manifest as a kinetic inductance, representing the reluctance of the collective mass to accelerate. However, at optical (infrared) frequencies, phase measurements of current are generally difficult, and, at microwave frequencies, the inertial phase delay has been buried under electron scattering. Therefore, to date, the collective mass in graphene has defied unequivocal measurement. Here, we directly and precisely measure the kinetic inductance, and therefore the collective mass, by combining device engineering that reduces electron scattering and sensitive microwave phase measurements. Specifically, the encapsulation of graphene between hexagonal boron nitride layers, one-dimensional edge contacts and a proximate top gate configured as microwave ground together enable the inertial phase delay to be resolved from the electron scattering. Beside its fundamental importance, the kinetic inductance is found to be orders of magnitude larger than the magnetic inductance, which may be utilized to miniaturize radiofrequency integrated circuits. Moreover, its bias dependency heralds a solid-state voltage-controlled inductor to complement the prevalent voltage-controlled capacitor.
Topological susceptibility from the twisted mass Dirac operator spectrum
Energy Technology Data Exchange (ETDEWEB)
Cichy, Krzysztof [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Poznan Univ. (Poland). Faculty of Physics; Garcia-Ramos, Elena [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Humboldt-Universitaet, Berlin (Germany); Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Collaboration: European Twisted Mass Collaboration
2013-12-15
We present results of our computation of the topological susceptibility with N{sub f}=2 and N{sub f}= +1+1 flavours of maximally twisted mass fermions, using the method of spectral projectors. We perform a detailed study of the quark mass dependence and discretization effects. We make an attempt to confront our data with chiral perturbation theory and extract the chiral condensate from the quark mass dependence of the topological susceptibility. We compare the value with the results of our direct computation from the slope of the mode number. We emphasize the role of autocorrelations and the necessity of long Monte Carlo runs to obtain results with good precision. We also show our results for the spectral projector computation of the ratio of renormalization constants Z{sub P}/Z{sub S}.
Topological susceptibility from the twisted mass Dirac operator spectrum
International Nuclear Information System (INIS)
Cichy, Krzysztof; Jansen, Karl; Cyprus Univ., Nicosia
2013-12-01
We present results of our computation of the topological susceptibility with N f =2 and N f = +1+1 flavours of maximally twisted mass fermions, using the method of spectral projectors. We perform a detailed study of the quark mass dependence and discretization effects. We make an attempt to confront our data with chiral perturbation theory and extract the chiral condensate from the quark mass dependence of the topological susceptibility. We compare the value with the results of our direct computation from the slope of the mode number. We emphasize the role of autocorrelations and the necessity of long Monte Carlo runs to obtain results with good precision. We also show our results for the spectral projector computation of the ratio of renormalization constants Z P /Z S .
Measuring neutrino mass imprinted on the anisotropic galaxy clustering
Energy Technology Data Exchange (ETDEWEB)
Oh, Minji; Song, Yong-Seon, E-mail: minjioh@kasi.re.kr, E-mail: ysong@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of)
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 m {sub ν} ∼< 1 eV limit in which the early broadband shape determined before the last scattering surface is immune from the variation of m {sub ν}. The signature of m {sub ν} is imprinted on the altered shape of the power spectrum at later epoch, which provides an opportunity to access the non-trivial m {sub ν} 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 m {sub ν} 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, m {sub ν} 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 m {sub ν} 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 m {sub ν}, and the m {sub ν} is observed to be m {sub ν} = 0.19{sup +0.28}{sub −0.17} eV which is different from massless neutrino at 68% confidence.
Leptoquark mechanism of neutrino masses within the grand unification framework
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.
Leptoquark mechanism of neutrino masses within the grand unification framework
Energy Technology Data Exchange (ETDEWEB)
Dorsner, Ilja [University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture in Split (FESB), Split (Croatia); Fajfer, Svjetlana; Kosnik, Nejc [University of Ljubljana, Department of Physics, Ljubljana (Slovenia); Jozef Stefan Institute, Jamova 39, P. O. Box 3000, Ljubljana (Slovenia)
2017-06-15
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{sub 3}-R{sub 2} and S{sub 1,3}-R{sub 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{sub 1,3}-R{sub 2} scenarios when the LQ masses are roughly between 10{sup 12} and 5 x 10{sup 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{sub 3}-R{sub 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{sub 3}-R{sub 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. (orig.)
International Nuclear Information System (INIS)
Pan Haijun; Cheng, G.
2002-01-01
As an extension of our previous work in the seesaw mechanism, we analyze the influence of nonzero U e3 on the properties (masses and mixing) of the right-handed Majorana neutrinos in three flavors. The quasidegenerate light neutrinos case is also considered. Assuming the hierarchical Dirac neutrino masses, we find the heavy Majorana neutrino mass spectrum is either hierarchical or partially degenerate if θ 23 ν is large. We show that degenerate right-handed (RH) Majorana masses correspond to a maximal RH mixing angle while hierarchical ones correspond to the RH mixing angles which scale linearly with the mass ratios of the Dirac neutrino masses. An interesting analogue to the behavior of the matter-enhanced neutrino conversion and their difference is presented
International Nuclear Information System (INIS)
Bahar, M.K.; Yasuk, F.
2012-01-01
The solutions of the effective mass Dirac equation for the Manning-Rosen potential with the centrifugal term are studied approximately in N dimension. The relativistic energy spectrum and two-component spinor eigenfunctions are obtained by the asymptotic iteration method. We have also investigated eigenvalues of the effective mass Dirac-Manning-Rosen problem for α = 0 or α = 1. In this case, the Manning-Rosen potential reduces to the Hulthen potential. (author)
Repressing Anarchy in Neutrino Mass Textures
Altarelli, Guido; Masina, Isabella; Merlo, Luca
2012-01-01
The recent results that $\\theta_{13}$ is relatively large, of the order of the previous upper bound, and the indications of a sizable deviation of $\\theta_{23}$ from the maximal value are in agreement with the predictions of Anarchy in the lepton sector. The quark and charged lepton hierarchies can then be reproduced in a SU(5) GUT context by attributing non-vanishing $U(1)_{FN}$ charges, different for each family, only to the SU(5) tenplet states. The fact that the observed mass hierarchies are stronger for up quarks than for down quarks and charged leptons supports this idea. As discussed in the past, in the flexible context of $SU(5)\\otimes U(1)_{FN}$, different patterns of charges can be adopted going from Anarchy to various types of hierarchy. We revisit this approach by also considering new models and we compare all versions to the present data. As a result we confirm that, by relaxing the extreme ansatz of equal $U(1)_{FN}$ charges for all SU(5) pentaplets and singlets, better agreement with the data t...
Quark-lepton complementarity relation and neutrino mass hierarchy
International Nuclear Information System (INIS)
Ferrandis, Javier; Pakvasa, Sandip
2005-01-01
Latest measurements have revealed that the deviation from a maximal solar mixing angle is approximately the Cabibbo angle [i.e., quark-lepton complementarity (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 renormalization group equations 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
Massive neutrinos flavor mixing of leptons and neutrino oscillations
2015-01-01
Since the discovery of neutrino oscillations neutrino physics has become an interesting field of research in physics. They imply that neutrino must have a small mass and that the neutrinos, coupled to the charged leptons, are mixtures of the mass eigenstates, analogous to the flavor mixing of the quarks. The mixing angles for the quarks are small, but for the leptons two of the mixing angles are large. The masses of the three neutrinos must be very small, less than 1 eV, but from the oscillation experiments we only know the mass differences — the absolute masses are still unknown. Also we do not know, if the masses of the neutrinos are Dirac masses, as the masses of the charged leptons and of the quarks, or whether they are Majorana masses. In this volume, an overview of the present state of research in neutrino physics is given by well-known experimentalists and theorists. The contents — originated from talks and discussions at a recent conference addressing some of the most pressing open questions in n...
Mixed Inert scalar triplet dark matter, radiative neutrino masses and leptogenesis
Directory of Open Access Journals (Sweden)
Wen-Bin Lu
2017-11-01
Full Text Available The neutral component of an inert scalar multiplet with hypercharge can provide a stable dark matter particle when its real and imaginary parts have a splitting mass spectrum. Otherwise, a tree-level dark-matter-nucleon scattering mediated by the Z boson will be much above the experimental limit. In this paper we focus on a mixed inert scalar triplet dark matter scenario where a complex scalar triplet with hypercharge can mix with another real scalar triplet without hypercharge through their renormalizable coupling to the standard model Higgs doublet. We consider three specified cases that carry most of the relevant features of the full parameter space: (i the neutral component of the real triplet dominates the dark matter particle, (ii the neutral component of the complex triplet dominates the dark matter particle; and (iii the neutral components of the real and complex triplets equally constitute the dark matter particle. Subject to the dark matter relic abundance and direct detection constraint, we perform a systematic study on the allowed parameter space with particular emphasis on the interplay among triplet-doublet terms and gauge interactions. In the presence of these mixed inert scalar triplets, some heavy Dirac fermions composed of inert fermion doublets can be utilized to generate a tiny Majorana neutrino mass term at one-loop level and realize a successful leptogenesis for explaining the cosmic baryon asymmetry.
Energy Technology Data Exchange (ETDEWEB)
Hernandez, A.E.C. [Universidad Tecnica Federico Santa Maria, Valparaiso (Chile); Martinez, R.; Ochoa, F. [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia)
2016-11-15
We propose a 3-3-1 model where the SU(3){sub C} x SU(3){sub L} x U(1){sub X} symmetry is extended by S{sub 3} x Z{sub 3} x Z{sub 3}{sup '} x Z{sub 8} x Z{sub 16} and the scalar spectrum is enlarged by extra SU(3){sub L} singlet scalar fields. The model successfully describes the observed SM fermion mass and mixing pattern. In this framework, the light active neutrino masses arise via an inverse seesaw mechanism and the observed charged fermion mass and quark mixing hierarchy is a consequence of the Z{sub 3} x Z{sub 3}{sup '} x Z{sub 8} x Z{sub 16} symmetry breaking at very high energy. The obtained physical observables for both quark and lepton sectors are compatible with their experimental values. The model predicts the effective Majorana neutrino mass parameter of neutrinoless double beta decay to be m{sub ββ} = 4 and 48 meV for the normal and the inverted neutrino spectra, respectively. Furthermore, we found a leptonic Dirac CP-violating phase close to (π)/(2) and a Jarlskog invariant close to about 3 x 10{sup -2} for both normal and inverted neutrino mass hierarchy. (orig.)
Dirac Particle for the Position Dependent Mass in the Generalized Asymmetric Woods-Saxon Potential
Directory of Open Access Journals (Sweden)
Soner Alpdoğan
2014-01-01
Full Text Available The one-dimensional Dirac equation with position dependent mass in the generalized asymmetric Woods-Saxon potential is solved in terms of the hypergeometric functions. The transmission and reflection coefficients are obtained by considering the one-dimensional electric current density for the Dirac particle and the equation describing the bound states is found by utilizing the continuity conditions of the obtained wave function. Also, by using the generalized asymmetric Woods-Saxon potential solutions, the scattering states are found out without making calculation for the Woods-Saxon, Hulthen, cusp potentials, and so forth, which are derived from the generalized asymmetric Woods-Saxon potential and the conditions describing transmission resonances and supercriticality are achieved. At the same time, the data obtained in this work are compared with the results achieved in earlier studies and are observed to be consistent.
Minimal flavour violation and neutrino masses without R-parity
DEFF Research Database (Denmark)
Arcadi, G.; Di Luzio, L.; Nardecchia, M.
2012-01-01
symmetry breaking all the couplings of the superpotential including the R-parity violating ones. If R-parity violation is responsible for neutrino masses, our setup can be seen as an extension of MFV to the lepton sector. We analyze two patterns based on the non-abelian flavour symmetries SU(3)(4) circle...... times SU(4) and SU(3)(5). In the former case the total lepton number and the lepton flavour number are broken together, while in the latter the lepton number can be broken independently by an abelian spurion, so that visible effects and peculiar correlations can be envisaged in flavour changing charged...
Determination of neutrino mass hierarchy by 21 cm line and CMB B-mode polarization observations
Energy Technology Data Exchange (ETDEWEB)
Oyama, Yoshihiko, E-mail: oyamayo@post.kek.jp [The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba 305-0801 (Japan); Shimizu, Akie [The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba 305-0801 (Japan); Kohri, Kazunori [The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba 305-0801 (Japan); Institute of Particle and Nuclear Studies, KEK, 1-1 Oho, Tsukuba 305-0801 (Japan)
2013-01-29
We focus on the ongoing and future observations for both the 21 cm line and the CMB B-mode polarization produced by a CMB lensing, and study their sensitivities to the effective number of neutrino species, the total neutrino mass, and the neutrino mass hierarchy. We find that combining the CMB observations with future square kilometer arrays optimized for 21 cm line such as Omniscope can determine the neutrino mass hierarchy at 2{sigma}. We also show that a more feasible combination of Planck + POLARBEAR and SKA can strongly improve errors of the bounds on the total neutrino mass and the effective number of neutrino species to be {Delta}{Sigma}m{sub {nu}}{approx}0.12 eV and {Delta}N{sub {nu}}{approx}0.38 at 2{sigma}, respectively.
Newest results from the Mainz neutrino-mass experiment
International Nuclear Information System (INIS)
Bonn, J.; Bornschein, B.; Bornschein, L.; Fickinger, L.; Kraus, Ch.; Otten, E.W.; Ulrich, H.; Weinheimer, Ch.; Kazachenko, O.; Kovalik, A.
2000-01-01
The Mainz neutrino-mass experiment investigates the endpoint region of the tritium β-decay spectrum with a MAC-E spectrometer to determine the mass of the electron antineutrino. By the recent upgrade, the former problem of dewetting T 2 films has been solved, and the signal-to-background ratio was improved by a factor of 10. The latest measurement leads to m ν 2 -3.7 ± 5.3(stat.) ± 2.1(syst.) eV 2 /c 4 , from which an upper limit of m ν 2 (95% C.L.) is derived. Some indication for the anomaly, reported by the Troitsk group, was found, but its postulated half-year period is contradicted by our data. To push the sensitivity on the neutrino mass below 1 eV/c 2 , a new larger MAC-E spectrometer is proposed. Besides its integrating mode, it could run in a new nonintegration operation MAC-E-TOF mode
Running of radiative neutrino masses: the scotogenic model — revisited
Energy Technology Data Exchange (ETDEWEB)
Merle, Alexander; Platscher, Moritz [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany)
2015-11-23
A few years ago, it had been shown that effects stemming from renormalisation group running can be quite large in the scotogenic model, where neutrinos obtain their mass only via a 1-loop diagram (or, more generally, in many models in which the light neutrino mass is generated via quantum corrections at loop-level). We present a new computation of the renormalisation group equations (RGEs) for the scotogenic model, thereby updating previous results. We discuss the matching in detail, in particular in what regards the different mass spectra possible for the new particles involved. We furthermore develop approximate analytical solutions to the RGEs for an extensive list of illustrative cases, covering all general tendencies that can appear in the model. Comparing them with fully numerical solutions, we give a comprehensive discussion of the running in the scotogenic model. Our approach is mainly top-down, but we also discuss an attempt to get information on the values of the fundamental parameters when inputting the low-energy measured quantities in a bottom-up manner. This work serves the basis for a full parameter scan of the model, thereby relating its low- and high-energy phenomenology, to fully exploit the available information.
International Nuclear Information System (INIS)
Novello, M.
1976-07-01
A class of solutions of DIRAC'S equation in gravitational fields for ghost neutrinos is given. Comments are restricted to the neutrino cosmological model recently found by M. Novello e I.D. Soares [pt
Abada, A
2000-01-01
We consider a general symmetric $(3\\times 3)$ mass matrix for three generations of neutrinos. Imposing the constraints, from the atmospheric neutrino and solar neutrino anomalies as well as from the CHOOZ experiment, on the mass squared differences and on the mixing angles, we identify the ranges of allowed inputs for the 6 matrix elements. We apply our results to Majorana left-handed neutrino masses generated at tree level and through The present experimental results on neutrinos from laboratories, cosmology and astrophysics are implemented to either put bounds on trilinear ($\\lambda_{ijk}, or constrain combinations of products of these couplings.
Seesaw induced electroweak scale, the hierarchy problem and sub-eV neutrino masses
International Nuclear Information System (INIS)
Atwood, D.; Bar-Shalom, S.; Soni, A.
2006-01-01
We describe a model for the scalar sector where all interactions occur either at an ultra-high scale, Λ U ∝10 16 -10 19 GeV, or at an intermediate scale, Λ I =10 9 -10 11 GeV. The interaction of physics on these two scales results in an SU(2) Higgs condensate at the electroweak (EW) scale, Λ EW , through a seesaw-like Higgs mechanism, Λ EW ∝Λ I 2 /Λ U , while the breaking of the SM SU(2) x U(1) gauge symmetry occurs at the intermediate scale Λ I . The EW scale is, therefore, not fundamental but is naturally generated in terms of ultra-high energy phenomena and so the hierarchy problem is alleviated. We show that the class of such ''seesaw Higgs'' models predict the existence of sub-eV neutrino masses which are generated through a ''two-step'' seesaw mechanism in terms of the same two ultra-high scales: m ν ∝Λ I 4 /Λ U 3 ∝Λ EW 2 /Λ U . The neutrinos can be either Dirac or Majorana, depending on the structure of the scalar potential. We also show that our seesaw Higgs model can be naturally embedded in theories with tiny extra dimensions of size R∝Λ U -1 ∝10 -16 fm, where the seesaw induced EW scale arises from a violation of a symmetry at a distant brane; in particular, in the scenario presented there are seven tiny extra dimensions. (orig.)
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.
Searches for heavy neutrinos from Z decays
International Nuclear Information System (INIS)
Abreu, P.; Adam, W.; Adami, F.
1992-01-01
We have searched for possible fourth family heavy neutrinos, pair produced in Z 0 decays, in a sample of about 112 000 hadronic Z 0 final states collected with the DELPHI detector. For all mixing matrix elements we exclude a new Dirac neutrino light than 44.5 GeV at a 95% confidence level, if the neutrino couples to the electron or muon family, and lighter than 44.0 GeV, if the neutrino couples to the tau family. Depending on the values of the mixing element and to which lepton family the neutrino couples, we obtain mass limits up to 46.2 GeV. For all mixing matrix elements we exclude a new Majorana neutrino lighter than 39.0 GeV, if it couples to the electron or the muon family, and lighter than 38.2 GeV, if it couples to the tau family. Depending on the values of the mixing matrix element and to which lepton family the neutrino couples, we obtain mass limits up to 44.7 GeV. We also exclude stable new Dirac neutrinos lighter than 45.0 GeV and new Majorana neutrinos lighter than 39.5 GeV. (orig.)
Double beta decay and majorana neutrinos. Right-handed currents or nonzero masses
International Nuclear Information System (INIS)
Rosen, S.P.; Perlmutter, A.
1981-01-01
This chapter describes some new developments concerning the mechanism for lepton number nonconservation in no-neutrino double beta decay. Explains that lepton number nonconservation in no-neutrino double beta decay comes about either because both left- and right-handed components of a Majorano neutrino are coupled to the electron in the weak leptonic current, or because the neutrino has nonzero mass. Shows that while nuclear ground-state to ground-state transitions arise from right-handed currents and from neutrino mass terms, transitions to low-lying excited states with J /SUP P/ =2 + can arise only from right-handed currents. Emphasizes that the possibilities of detecting small admixtures of right-handed currents, and of setting limits on neutrino masses that are either very small or very large, make double beta decay a most rewarding phenomenon to study
International Nuclear Information System (INIS)
Zee, A.
1985-09-01
A brief review is given of the basics of fractional statistics, which is based on the Dirac-Bohm-Aharanov effect. Some group theoretic aspects of exceptional preons are breifly described, and a theory is proposed containing hypercolor and hyperflavor with G/sub HC/ x G/sub HF/ = E(6) x E(6) and preons in (27,27). It is also suggested that the dark matter in the universe is due to a scalar field which transforms as a singlet under SU(3) x SU(2) x U(1) and interacts only via the Higgs boson. Some speculation is made on the existence and physical consequences of a SU(2) singet charged scalar field which couples to two lepton doublet, necessarily violating electron, muon, and tauon numbers. The Majorana masses of neutrinos are discussed as the result of breaking the total lepton number. Abelian gauge field hidden inside non-abelian gauge theory is briefly described in analogy to the electromagnetic potential term. 20 refs
Measuring neutrino masses with a future galaxy survey
DEFF Research Database (Denmark)
Hamann, Jan; Hannestad, Steen; Wong, Yvonne Y. Y.
2012-01-01
that the minimum mass sum of sum m_nu ~ 0.06 eV in the normal hierarchy can be detected at 1.5 sigma to 2.5 sigma 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 5.4 sigma. 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......) 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 (Delta chi_eff ^2
A model of radiative neutrino masses. Mixing and a possible fourth generation
International Nuclear Information System (INIS)
Babu, K.S.; Ma, E.; Pantaleone, J.
1989-01-01
We consider the phenomenological consequences of a recently proposed model with four lepton generations such that the three known neutrinos have radiatively induced Majorana masses. Mixing among generations in the presence of a heavy fourth neutrino necessitates a reevaluation of the usual experimental tests of the standard model. One interesting possibility is to have a τ lifetime longer than predicted by the standard three-generation model. Another is to have neutrino masses and mixing angles in the range needed for a natural explanation of the solar-neutrino puzzle in terms of the Mikheyev-Smirnov-Wolfenstein effect. (orig.)
LSND versus MiniBooNE: Sterile neutrinos with energy dependent masses and mixing?
Schwetz, Thomas
2008-01-01
Standard active-sterile neutrino oscillations do not provide a satisfactory description of the LSND evidence for neutrino oscillations together with the constraints from MiniBooNE and other null-result short-baseline oscillation experiments. However, if the mass or the mixing of the sterile neutrino depends in an exotic way on its energy all data become consistent. I explore the phenomenological consequences of the assumption that either the mass or the mixing scales with the neutrino energy as $1/E_\
More is different: Reconciling eV sterile neutrinos with cosmological mass bounds
Directory of Open Access Journals (Sweden)
Yong Tang
2015-11-01
Full Text Available 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.
Knitting neutrino mass textures with or without Tri-Bi maximal mixing
Energy Technology Data Exchange (ETDEWEB)
Leontaris, G.K., E-mail: leonta@uoi.gr [Theoretical Physics Division, Ioannina University, GR-45110 Ioannina (Greece); Vlachos, N.D. [Theoretical Physics Division, Aristotle University, GR-54124 Thessaloniki (Greece)
2011-08-03
The solar and baseline neutrino oscillation data suggest bimaximal neutrino mixing among the first two generations, and trimaximal mixing between all three neutrino flavors. It has been conjectured that this indicates the existence of an underlying symmetry for the leptonic fermion mass textures. The experimentally measured quantities, however, are associated to the latter indirectly and in a rather complicated way through the mixing matrices of the charged leptons and neutrinos. Motivated by these facts, we derive exact analytical expressions which directly link the charged lepton and neutrino mass and mixing parameters to measured quantities and obtain constraints on the parameter space. We discuss deviations from Tri-Bi mixing matrices and present minimal extensions of the Harrison, Perkins and Scott matrices capable of interpreting all neutrino data.
Study of the mass of the electron neutrino in Japan
International Nuclear Information System (INIS)
Yasumi, Shinjiro; Maezawa, Hideki
1996-02-01
This report describes a study of the mass of the electron neutrino using electron capture in 163 Ho in Japan for the period from 1981 to 1994. This monograph has two purposes, one is to supplement the papers on the mass of the electron neutrino already published by us and another is to make a record on some details of our experiments for future. Electron capture in a nucleus takes place in a rather small space inside an atom, where atomic physics, nuclear physics and particle physics work closely together. Therefore, this study needed an intimate collaboration of atomic physicists, nuclear physicists and particle physicists. In addition, it was necessary for this study to use various fine techniques, including metallurgy, production of 163 Ho activity, micro-analysis by wet chemistry, isotope-dilution mass spectrometry, undulator radiation source technology, the soft X-ray monochromator technology, a counting technique for very intense soft X-rays and so on. As a result, our collaboration consisted of many researchers from various fields as follows; M. Ando, H. Arai, M. Fujioka, N. Hashimoto, H. Ikeda, Y. Inagaki, K. Ishii, K. Itoh, G. Izawa, O. Kawakami, S. Kishimoto, H. Kitamura, H. Maezawa, M. Maruyama, A. Masuda, K. Masumoto, A. Mikuni, T. Mizogawa, T. Mukoyama, F. Ochiai, T. Ohta, T. Omori, G. Rajasekaran, K. Sera, K. Shima, T. Shinozuka, P.M. Stefan, I. Sugai, H. Taketani, M. Yagi, and S. Yasumi. Without such an excellent collaboration, this study would not have been completed. We would like to express our sincere gratitude to Professor T. Sasaki for supporting this study and recommending the undulator beam line of 2.5 GeV Photon Factory Storage Ring as a light source to be used in the experiment. We also would like to thank Dr. A. Yagishita and Dr. Y. Kitajima who are responsible for the BL-2 beamline. Finally we are grateful to Ms. M. Noji for her patient typewriting of manuscripts written by hand. (author)
Compromise between neutrino masses and collider signatures in the type-II seesaw model
International Nuclear Information System (INIS)
Chao Wei; Luo Shu; Xing Zhizhong; Zhou Shun
2008-01-01
A natural extension of the standard SU(2) L xU(1) Y gauge model to accommodate massive neutrinos is to introduce one Higgs triplet and three right-handed Majorana neutrinos, leading to a 6x6 neutrino mass matrix which contains three 3x3 submatrices, M L , M D and M R . We show that three light Majorana neutrinos (i.e., the mass eigenstates of ν e , ν μ , and ν τ ) are exactly massless in this model, if and only if M L =M D M R -1 M D T exactly holds. This no-go theorem implies that small but nonvanishing neutrino masses may result from a significant but incomplete cancellation between M L and M D M R -1 M D T terms in the Type-II seesaw formula, provided three right-handed Majorana neutrinos are of O(1) TeV and experimentally detectable at the LHC. We propose three simple Type-II seesaw scenarios with the A 4 xU(1) X flavor symmetry and its explicit breaking to interpret the observed neutrino mass spectrum and neutrino mixing pattern. Such a TeV-scale neutrino model can be tested in two complementary ways: (1) searching for possible collider signatures of lepton number violation induced by the right-handed Majorana neutrinos and doubly-charged Higgs particles; and (2) searching for possible consequences of unitarity violation of the 3x3 neutrino mixing matrix in the future long-baseline neutrino oscillation experiments
A light Zeldovich-Konopinski-Mahmoud neutrino with a large magnetic moment
International Nuclear Information System (INIS)
Ecker, G.; Grimus, W.; Neufeld, H.
1989-08-01
We propose a non-Abelian extension of a Zeldovich-Konopinski-Mahmoud lepton number symmetry which gives rise to a naturally light Dirac neutrino with a magnetic moment of O(10 -11 μ B ). The neutrino mass appears first at the two-loop level and is well below the experimental upper bound. 13 refs., 3.figs. (Authors)
Some unsettled questions in the problem of neutrino oscillations
International Nuclear Information System (INIS)
Beshtoev, Kh.M.
2003-01-01
It is noted that the theory of neutrino oscillations can be constructed only in the framework of the particle physics theory where a mass shell conception is presented and then transitions (oscillations) between neutrinos with equal masses are real and between neutrinos with different masses are virtual. There can be three types of neutrino transitions. In the experiments it is necessary to decide the question: which type of neutrino transitions is realized in nature? At present it is supposed that Dirac and Majorana neutrino oscillations can be realized. It is shown that we cannot put Majorana neutrinos in the standard weak interaction theory without violation of the gauge invariance. If we use the Majorana neutrinos then we come to contradiction with the existing experimental data. Then it is obvious that there can be only realized transitions between Dirac neutrinos with different flavors. It is also shown that the mechanism of resonance enhancement of neutrino oscillations in matter cannot be realized without violation of the law of energy-momentum conservation. Though it is supposed that in experiments we see neutrino oscillations, indeed only transitions between neutrinos are registered.To register neutrino oscillations, it is necessary to see second or even higher neutrino oscillation modes in experiments. For this purpose we can use the elliptic character of the Earth orbit at registrations of sun neutrinos. The analysis shows that the SNO experimental results do not confirm smallness of ν e → ν τ transition angle mixing, which was obtained in the CHOOZ experiment. It is also noted that there is contradiction between the SNO, Super-Kamiokande, Homestake and SAGE, and GNO (GALLEX) data. (author)
Neutrino masses, scale-dependent growth, and redshift-space distortions
Energy Technology Data Exchange (ETDEWEB)
Hernández, Oscar F., E-mail: oscarh@physics.mcgill.ca [Marianopolis College, 4873 Westmount Ave., Westmount, QC H3Y 1X9 (Canada)
2017-06-01
Massive neutrinos leave a unique signature in the large scale clustering of matter. We investigate the wavenumber dependence of the growth factor arising from neutrino masses and use a Fisher analysis to determine the aspects of a galaxy survey needed to measure this scale dependence.
International Nuclear Information System (INIS)
Kirilova, D.P.; Chizhov, M.V.
1998-05-01
We study the nonresonant oscillations between left-handed electron neutrinos ν s and nonthermalized sterile neutrinos ν s in the early Universe plasma. The case when ν s do not thermalize till 2 MeV and the oscillations become effective after ν e decoupling is discussed. As far as for this model the rates of expansion of the Universe, neutrino oscillations and neutrino interactions with the medium may be comparable, we have analyzed the kinetic equations for neutrino density matrix, accounting simultaneously for these processes. The evolution of neutrino ensembles was described numerically by integrating the kinetic equations for the neutrino density matrix in momentum space for small mass differences δm 2 ≤10 -7 eV 2 . This approach allowed us to study precisely the evolution of the neutrino number densities, energy spectrum distortion and the asymmetry between neutrinos and antineutrinos due to oscillations for each momentum mode. We have performed a complete numerical analysis for the full range of the oscillations parameters of the model of the influence of the nonequilibrium ν e ↔ν s oscillations on the primordial production of 4 He. The exact kinetic approach enabled us to calculate the effects of neutrino population depletion, the distortion of the neutrino spectrum and the generation of neutrino-antineutrino asymmetry on the kinetics of neutron-to-proton transitions during the primordial nucleosynthesis epoch and correspondingly on the cosmological 4 He production. It was shown that the neutrino population depletion and spectrum distortion play an important role. The asymmetry effect, in case the lepton asymmetry is accepted initially equal to the baryon one, is proved to be negligible for the discussed range of δm 2 . Constant helium contours in δm 2 -θ plane were calculated. Thanks to the exact kinetic approach more precise cosmological constraints on the mixing parameters were obtained. (author)
TRIMS: Validating T2 Molecular Effects for Neutrino Mass Experiments
Lin, Ying-Ting; Trims Collaboration
2017-09-01
The Tritium Recoil-Ion Mass Spectrometer (TRIMS) experiment examines the branching ratio of the molecular tritium (T2) beta decay to the bound state (3HeT+). Measuring this branching ratio helps to validate the current molecular final-state theory applied in neutrino mass experiments such as KATRIN and Project 8. 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 the apparatus, simulation software, and analysis tools, including efforts to improve the resolution of our detectors and to characterize the stability and uniformity of our field sources. We will also share our commissioning results and prospects for physics data. The TRIMS experiment is supported by U.S. Department of Energy Office of Science, Office of Nuclear Physics, Award Number DE-FG02-97ER41020.
Dark matter stability and one-loop neutrino mass generation based on Peccei-Quinn symmetry
Energy Technology Data Exchange (ETDEWEB)
Suematsu, Daijiro [Kanazawa University, Institute for Theoretical Physics, Kanazawa (Japan)
2018-01-15
We propose a model which is a simple extension of the KSVZ invisible axion model with an inert doublet scalar. Peccei-Quinn symmetry forbids tree-level neutrino mass generation and its remnant Z{sub 2} symmetry guarantees dark matter stability. The neutrino masses are generated by one-loop effects as a result of the breaking of Peccei-Quinn symmetry through a nonrenormalizable interaction. Although the low energy effective model coincides with an original scotogenic model which contains right-handed neutrinos with large masses, it is free from the strong CP problem. (orig.)
Dark matter stability and one-loop neutrino mass generation based on Peccei-Quinn symmetry
Suematsu, Daijiro
2018-01-01
We propose a model which is a simple extension of the KSVZ invisible axion model with an inert doublet scalar. Peccei-Quinn symmetry forbids tree-level neutrino mass generation and its remnant Z_2 symmetry guarantees dark matter stability. The neutrino masses are generated by one-loop effects as a result of the breaking of Peccei-Quinn symmetry through a nonrenormalizable interaction. Although the low energy effective model coincides with an original scotogenic model which contains right-handed neutrinos with large masses, it is free from the strong CP problem.
Neutrino masses from U(1) symmetries and the Super-Kamiokande data
Lola, S; Lola, Smaragda; Ross, Graham G.
1999-01-01
Motivated by the Super-Kamiokande data, we revisit models with U(1) symmetries and discuss the origin of neutrino masses and mixings in such theories. We show that, in models with just three light neutrinos and a hierarchy of neutrino masses, large (2-3) mixing fixes the lepton doublet U(1) charges and is thus related to the structure of the charged lepton mass matrix. We discuss the fermion mass structure that follows from the abelian family symmetry with an extended gauge group. Requiring that the quark and lepton masses be ordered by the family symmetry, we identify the most promising scheme. This requires large, but not necessarily maximal, mixing in the mu tau sector and gives e mu mixing in the range that is required for the small angle solution of the solar neutrino deficit.
Study of the mass of the electron neutrino in Japan
Energy Technology Data Exchange (ETDEWEB)
Yasumi, Shinjiro; Maezawa, Hideki [eds.
1996-02-01
This report describes a study of the mass of the electron neutrino using electron capture in {sup 163}Ho in Japan for the period from 1981 to 1994. This monograph has two purposes, one is to supplement the papers on the mass of the electron neutrino already published by us and another is to make a record on some details of our experiments for future. Electron capture in a nucleus takes place in a rather small space inside an atom, where atomic physics, nuclear physics and particle physics work closely together. Therefore, this study needed an intimate collaboration of atomic physicists, nuclear physicists and particle physicists. In addition, it was necessary for this study to use various fine techniques, including metallurgy, production of {sup 163}Ho activity, micro-analysis by wet chemistry, isotope-dilution mass spectrometry, undulator radiation source technology, the soft X-ray monochromator technology, a counting technique for very intense soft X-rays and so on. As a result, our collaboration consisted of many researchers from various fields as follows; M. Ando, H. Arai, M. Fujioka, N. Hashimoto, H. Ikeda, Y. Inagaki, K. Ishii, K. Itoh, G. Izawa, O. Kawakami, S. Kishimoto, H. Kitamura, H. Maezawa, M. Maruyama, A. Masuda, K. Masumoto, A. Mikuni, T. Mizogawa, T. Mukoyama, F. Ochiai, T. Ohta, T. Omori, G. Rajasekaran, K. Sera, K. Shima, T. Shinozuka, P.M. Stefan, I. Sugai, H. Taketani, M. Yagi, and S. Yasumi. Without such an excellent collaboration, this study would not have been completed. We would like to express our sincere gratitude to Professor T. Sasaki for supporting this study and recommending the undulator beam line of 2.5 GeV Photon Factory Storage Ring as a light source to be used in the experiment. We also would like to thank Dr. A. Yagishita and Dr. Y. Kitajima who are responsible for the BL-2 beamline. Finally we are grateful to Ms. M. Noji for her patient typewriting of manuscripts written by hand. (author).
Looking for Cosmic Neutrino Background
Directory of Open Access Journals (Sweden)
Chiaki eYanagisawa
2014-06-01
Full Text Available Since the discovery of neutrino oscillation in atmospheric neutrinos by the Super-Kamiokande experiment in 1998, study of neutrinos has been one of exciting fields in high-energy physics. All the mixing angles were measured. Quests for 1 measurements of the remaining parameters, the lightest neutrino mass, the CP violating phase(s, and the sign of mass splitting between the mass eigenstates m3 and m1, and 2 better measurements to determine whether the mixing angle theta23 is less than pi/4, are in progress in a well-controlled manner. Determining the nature of neutrinos, whether they are Dirac or Majorana particles is also in progress with continuous improvement. On the other hand, although the ideas of detecting cosmic neutrino background have been discussed since 1960s, there has not been a serious concerted effort to achieve this goal. One of the reasons is that it is extremely difficult to detect such low energy neutrinos from the Big Bang. While there has been tremendous accumulation of information on Cosmic Microwave Background since its discovery in 1965, there is no direct evidence for Cosmic Neutrino Background. The importance of detecting Cosmic Neutrino Background is that, although detailed studies of Big Bang Nucleosynthesis and Cosmic Microwave Background give information of the early Universe at ~a few minutes old and ~300 k years old, respectively, observation of Cosmic Neutrino Background allows us to study the early Universe at $sim$ 1 sec old. This article reviews progress made in the past 50 years on detection methods of Cosmic Neutrino Background.
Interplay of type I and type II seesaw contributions to neutrino mass
International Nuclear Information System (INIS)
Akhmedov, Evgeny Kh.; Frigerio, Michele
2007-01-01
Type I and type II seesaw contributions to the mass matrix of light neutrinos are inherently related if left-right symmetry is realized at high energy scales. We investigate implications of such a relation for the interpretation of neutrino data. We proved recently that the left-right symmetric seesaw equation has eight solutions, related by a duality property, for the mass matrix of right-handed neutrinos M R . In this paper the eight allowed structures of M R are reconstructed analytically and analyzed numerically in a bottom-up approach. We study the dependence of right-handed neutrino masses on the mass spectrum of light neutrinos, mixing angle θ 13 , leptonic CP violation, scale of left-right symmetry breaking and on the hierarchy in neutrino Yukawa couplings. The structure of the seesaw formula in several specific SO(10) models is explored in the light of the duality. The outcome of leptogenesis may depend crucially on the choice among the allowed structures of M R and on the level crossing between right-handed neutrino masses
Neutrino mass and mixing: from theory to experiment
International Nuclear Information System (INIS)
King, Stephen F; Merle, Alexander; Morisi, Stefano; Shimizu, Yusuke; Tanimoto, Morimitsu
2014-01-01
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
Can the neutrino mass be measured using /sup 163/Ho electron capture
International Nuclear Information System (INIS)
Bennett, C.L.
1985-01-01
The safest limit on the neutrino mass comes from allowing the interference amplitude to be a free parameter in a fit to Springer's inner bremsstrahlung data while fixing the Q value to its upper limit based on the results of the relative capture rates from F. Hartmann's data. Since /sup 163/Ho was the most promising electron capture candidate for a neutrino mass detector, it is unlikely that electron capture will ever compete with tritium beta decay in terms of sensitivity to neutrino mass. The best fundamental thing that can be said is that the limit of the difference in the mass of the neutrino and its anti-particle is smaller in absolute value than for any other fermion anti-fermion pair
Search for indications of the neutrino mass hierarchy using IceCube/DeepCore
Energy Technology Data Exchange (ETDEWEB)
Leuermann, Martin; Vehring, Markus; Wallraff, Marius; Wiebusch, Christopher [III. Physikalisches Institut B, RWTH Aachen (Germany); Collaboration: IceCube-Collaboration
2016-07-01
In 2015, the Nobel prize in physics was awarded for ''the discovery of neutrino oscillations, which shows that neutrinos have mass'', showing the high relevance of neutrino masses for modern particle physics. However, the ordering of the three neutrino masses is still unknown and is often referred to as neutrino mass hierarchy. Its measurement is a major goal for future experiments. One strategy is to measure matter effects in the oscillation pattern of atmospheric neutrinos e.g. as proposed for the PINGU extension of the IceCube neutrino observatory. Already now, the IceCube/DeepCore detector at the Geographic South Pole can be used to search for this signature. In this talk, we present an analysis based on data taken between 2011 and 2015. Due to recent improvements in the detector's reconstruction performance and the quality of the data selection, a measurement on the significance level of 1 sigma is expected.
A radiative neutrino mass model in light of DAMPE excess with hidden gauged U(1) symmetry
Nomura, Takaaki; Okada, Hiroshi; Wu, Peiwen
2018-05-01
We propose a one-loop induced neutrino mass model with hidden U(1) gauge symmetry, in which we successfully involve a bosonic dark matter (DM) candidate propagating inside a loop diagram in neutrino mass generation to explain the e+e‑ excess recently reported by the DArk Matter Particle Explorer (DAMPE) experiment. In our scenario dark matter annihilates into four leptons through Z' boson as DM DM → Z' Z' (Z' → l+ l‑) and Z' decays into leptons via one-loop effect. We then investigate branching ratios of Z' taking into account lepton flavor violations and neutrino oscillation data.
Neutrino masses in the SU(5) x (lower case x) SU(5)' mirror symmetric model
International Nuclear Information System (INIS)
Collie, M.; Foot, R.
1998-02-01
Motivated by the atmospheric and solar neutrino anomalies, we study neutrino masses in a parity invariant SU(5) x SU(5)' grand unified model. Two distinct ways of incorporating neutrino masses into this model are envisaged. One way involves adding a gauge singlet fermion to each generation. The other way, is to extend the scalar sector. This possibility suggests that photon - mirror photon kinetic mixing is non-zero since is generated radiatively. It is argued that the kinetic mixing is such models may well be close to the experimental limit
Neutrino masses, dark matter and leptogenesis with U(1) B - L gauge symmetry
Geng, Chao-Qiang; Okada, Hiroshi
2018-06-01
We propose a model with an U(1) B - L gauge symmetry, in which small neutrino masses, dark matter and the matter-antimatter asymmetry in the Universe can be simultaneously explained. In particular, the neutrino masses are generated radiatively, while the matter-antimatter asymmetry is led by the leptogenesis mechanism, at TeV scale. We also explore allowed regions of the model parameters and discuss some phenomenological effects, including lepton flavor violating processes.
Oblique corrections in a model with neutrino masses and strong C P resolution
International Nuclear Information System (INIS)
Natale, A.A.; Rodrigues da Silva, P.S.
1994-01-01
Our intention in this work is to verify what is the order of the limits we obtain on the light neutrino masses, through the calculation and comparison of the oblique corrections with the experimental data. The calculation will be performed for a specific model, although we expect it to be sufficiently general to give one idea of the limits that can be obtained on neutrino masses in this class of models. (author)
Molecular effects in the neutrino mass determination from beta-decay of the tritium molecule
International Nuclear Information System (INIS)
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
See-saw enhancement of neutrino mixing due to the right-handed phases
International Nuclear Information System (INIS)
Tanimoto, M.
1994-11-01
We study the see-saw enhancement mechanism in presence of the right-handed phases of the Dirac neutrino mass matrix and the Majorana mass matrix. The enhancement condition given by Smirnov is modified. We point out that the see-saw enhancement could be obtained due to the right-handed phases even if the Majorana matrix is proportional to the unit matrix. We show a realistic Dirac mass matrix which causes the see-saw enhancement. (author)
A Dynamical Origin of the Mass Hierarchy among Neutrinos, Charged Leptons, and Quarks
Akama, Keiichi; Katsuura, Kazuo
1998-01-01
We propose a dynamical mass-generation scenario which naturally realizes the mass hierarchy among the neutrinos, charged leptons and quarks, where the mass is dominated by the self-mass induced through the anomalous (i.e. non-minimal) gauge interactions.
Measuring the neutrino mass hierarchy with the future KM3NeT/ORCA detector
Energy Technology Data Exchange (ETDEWEB)
Hofestaedt, Jannik
2017-02-22
The neutrino mass hierarchy can be determined by measuring the energy- and zenith-angle-dependent oscillation pattern of few-GeV atmospheric neutrinos that have traversed the Earth. This measurement is the main science goal of KM3NeT/ORCA ('Oscillation Research with Cosmics in the Abyss'), a planned multi-megaton underwater Cherenkov detector in the Mediterranean Sea. A key task is the reconstruction of shower-like events induced by electron neutrinos in charged-current interactions, which substantially affect the neutrino mass hierarchy sensitivity. In this thesis, numerous aspects of the expected neutrino detection performance of the planned ORCA detector are investigated. A new reconstruction algorithm for neutrino-induced shower-like events is developed. Excellent reconstruction accuracies are achieved, with a neutrino energy resolution better than 26%/24%, and a median neutrino direction resolution better than 11 /9 for electron neutrinos/antineutrinos in charged-current interactions with energies above 7 GeV. It is shown that these resolutions are close to the reconstruction accuracy limits imposed by intrinsic fluctuations in the Cherenkov light signatures. These intrinsic resolution limits are based on generic assumptions about event reconstruction in Cherenkov detectors and are derived as part of this thesis. Differences in event reconstruction capabilities between water- and ice-based Cherenkov detectors are discussed. The configuration of existing trigger algorithms is optimised for the ORCA detector. Based on the developed shower reconstruction, a detector optimisation study of the photosensor density is performed. In addition, it is shown that optical background noise in the deep Mediterranean Sea is not expected to compromise the feasibility of the neutrino mass hierarchy measurement with ORCA. Together, these investigations contribute significantly to the estimated neutrino mass hierarchy sensitivity of ORCA published in the 'Letter of
Leptogenesis and low energy CP-violation in neutrino physics
International Nuclear Information System (INIS)
Pascoli, S.; Petcov, S.T.; Riotto, A.
2007-01-01
Taking into account the recent progress in the understanding of the lepton flavor effects in leptogenesis, we investigate in detail the possibility that the CP-violation necessary for the generation of the baryon asymmetry of the Universe is due exclusively to the Dirac and/or Majorana CP-violating phases in the PMNS neutrino mixing matrix U, and thus is directly related to the low energy CP-violation in the lepton sector (e.g., in neutrino oscillations, etc.). We first derive the conditions of CP-invariance of the neutrino Yukawa couplings λ in the see-saw Lagrangian, and of the complex orthogonal matrix R in the 'orthogonal' parametrization of λ. We show, e.g. that under certain conditions (i) real R and specific CP-conserving values of the Majorana and Dirac phases can imply CP-violation, and (ii) purely imaginary R does not necessarily imply breaking of CP-symmetry. We study in detail the case of hierarchical heavy Majorana neutrino mass spectrum, presenting results for three possible types of light neutrino mass spectrum: (i) normal hierarchical, (ii) inverted hierarchical, and (iii) quasi-degenerate. Results in the alternative case of quasi-degenerate in mass heavy Majorana neutrinos, are also derived. The minimal supersymmetric extension of the standard theory with right-handed Majorana neutrinos and see-saw mechanism of neutrino mass generation is discussed as well. We illustrate the possible correlations between the baryon asymmetry of the Universe and (i) the rephasing invariant J CP controlling the magnitude of CP-violation in neutrino oscillations, or (ii) the effective Majorana mass in neutrinoless double beta decay, in the cases when the only source of CP-violation is respectively the Dirac or the Majorana phases in the neutrino mixing matrix
Neutrino mass, the right-handed interaction and the double beta decay, 1
International Nuclear Information System (INIS)
Doi, Masaru; Kotani, Tsuneyuki; Nishiura, Hiroyuki; Okuda, Kazuko; Takasugi, Eiichi.
1981-01-01
In order to shed light on the important question whether neutrinos are Dirac or Majorana particles, the double β decay is investigated within a general form of weak interaction Hamiltonian. The systematic study is made on the 0 + → J + nuclear transitions for the two-neutrino and neutrinoless modes both in the two-nucleon- and N*-mechanism. It is shown that for the neutrinoless mode, only the 0 + → 0 + transition in the two-nucleon mechanism is allowed if there is no right-handed interaction. When the right-handed interaction gives a sizable contribution, the role of the 0 + → 2 + transition becomes as important as the 0 + → 0 + transition. The comparison of our results with the previous ones is also presented. (author)
Experimental tests for the Babu-Zee two-loop model of Majorana neutrino masses
International Nuclear Information System (INIS)
Sierra, Diego Aristizabal; Hirsch, Martin
2006-01-01
The smallness of the observed neutrino masses might have a radiative origin. Here we revisit a specific two-loop model of neutrino mass, independently proposed by Babu and Zee. We point out that current constraints from neutrino data can be used to derive strict lower limits on the branching ratio of flavour changing charged lepton decays, such as μ→eγ. Non-observation of Br(μ→eγ) at the level of 10 -13 would rule out singly charged scalar masses smaller than 590 GeV (5.04 TeV) in case of normal (inverse) neutrino mass hierarchy. Conversely, decay branching ratios of the non-standard scalars of the model can be fixed by the measured neutrino angles (and mass scale). Thus, if the scalars of the model are light enough to be produced at the LHC or ILC, measuring their decay properties would serve as a direct test of the model as the origin of neutrino masses
Experimental tests for the Babu-Zee two-loop model of Majorana neutrino masses
International Nuclear Information System (INIS)
Aristizabal, D.
2006-01-01
Abstract: The smallness of the observed neutrino masses might have a radiative origin. Here we revisit a specific two-loop model of neutrino mass, independently proposed by Babu and Zee. We point out that current constraints from neutrino data can be used to derive strict lower limits on the branching ratio of flavour changing charged lepton decays, such as μ → e γ. Non-observation of Br(μ → e γ) at the level of 10 -13 would rule out singly charged scalar masses smaller than 590 GeV (5.04 TeV) in case of normal (inverse) neutrino mass hierarchy. Conversely, decay branching ratios of the non-standard scalars of the model can be fixed by the measured neutrino angles (and mass scale). Thus, if the scalars of the model are light enough to be produced at the LHC or ILC, measuring their decay properties would serve as a direct test of the model as the origin of neutrino masses. (author)
Closing in on minimal dark matter and radiative neutrino masses
Energy Technology Data Exchange (ETDEWEB)
Sierra, D. Aristizabal [IFPA, Dép. AGO, Université de Liège, Bât B5, Sart Tilman B-4000 Liège 1 (Belgium); Departamento de Física, Universidad Técnica Federico Santa María, Casilla 110-V, Avda. España 1680, Valparaiso (Chile); Simoes, C.; Wegman, D. [IFPA, Dép. AGO, Université de Liège, Bât B5, Sart Tilman B-4000 Liège 1 (Belgium)
2016-06-20
We study one-loop radiative neutrino mass models in which one of the beyond-the-standard model fields is either a hypercharge-zero fermion quintet (minimal dark matter) or a hypercharge-zero scalar septet. By systematically classifying all possible one-loop such models we identify various processes that render the neutral component of these representations (dark matter) cosmologically unstable. Thus, our findings show that these scenarios are in general not reconcilable with dark matter stability unless tiny couplings or additional ad hoc symmetries are assumed, in contrast to minimal dark matter models where stability is entirely due to the standard model gauge symmetry. For some variants based on higher-order loops we find that α{sub 2} reaches a Landau pole at rather low scales, a couple orders of magnitude from the characteristic scale of the model itself. Thus, we argue that some of these variations although consistent with dark matter stability and phenomenological constraints are hard to reconcile with perturbativity criteria.
Neutrino masses in RPV models with two pairs of Higgs doublets
Energy Technology Data Exchange (ETDEWEB)
Grossman, Yuval [Laboratory for Elementary-Particle Physics, Cornell University,Ithaca, N.Y. (United States); Peset, Clara [Institut de Fisica d’Altes Energies (IFAE), Universitat Autònoma de Barcelona,08193 Bellaterra, Barcelona (Spain)
2014-04-07
We study the generation of neutrino masses and mixing in supersymmetric R-parity violating models containing two pairs of Higgs doublets. In these models, new RPV terms H^{sub D{sub 1}}H^{sub D{sub 2}}E^ arise in the superpotential, as well as new soft terms. Such terms give new contributions to neutrino masses. We identify the different parameters and suppression/enhancement factors that control each of these contributions. At tree level, just like in the MSSM, only one neutrino acquires a mass due to neutrino-neutralino mixing. There are no new one loop effects. We study the two loop contributions and find the conditions under which they can be important.
Search for heavy sterile neutrinos in trileptons at the LHC
Energy Technology Data Exchange (ETDEWEB)
Dib, Claudio O. [Univ. Tecnica Federico Santa Maria, Valparaiso (Chile). CCTVal y Dept. of Physics; Kim, C.S. [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Physics and IPAP; Wang, Kechen [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Chinese Academy of Sciences, Beijing (China). Center for Future High Energy Physics
2017-03-15
We present a search strategy for both Dirac and Majorana sterile neutrinos from the purely leptonic decays of W{sup ±}→e{sup ±}e{sup ±}μ{sup -+}ν and μ{sup ±}μ{sup ±}e{sup -+}ν at the 14 TeV LHC. The discovery and exclusion limits for sterile neutrinos are shown using both the Cut-and-Count (CC) and Multi-Variate Analysis (MVA) methods. We also discriminate between Dirac and Majorana sterile neutrinos by exploiting a set of kinematic observables which differ between the Dirac and Majorana cases. We find that the MVA method, compared to the more common CC method, can greatly enhance the discovery and discrimination limits. Two benchmark points with sterile neutrino mass m{sub N}=20 GeV and 50 GeV are tested. For an integrated luminosity of 3000 fb{sup -1}, sterile neutrinos can be found with 5σ significance if heavy-to-light neutrino mixings vertical stroke U{sub Ne} vertical stroke {sup 2}∝ vertical stroke U{sub Nμ} vertical stroke {sup 2}∝10{sup -6}, while Majorana vs. Dirac discrimination can be reached if at least one of the mixings is of order 10{sup -5}.
Search for heavy sterile neutrinos in trileptons at the LHC
International Nuclear Information System (INIS)
Dib, Claudio O.; Kim, C.S.; Wang, Kechen; Chinese Academy of Sciences, Beijing
2017-03-01
We present a search strategy for both Dirac and Majorana sterile neutrinos from the purely leptonic decays of W"±→e"±e"±μ"-"+ν and μ"±μ"±e"-"+ν at the 14 TeV LHC. The discovery and exclusion limits for sterile neutrinos are shown using both the Cut-and-Count (CC) and Multi-Variate Analysis (MVA) methods. We also discriminate between Dirac and Majorana sterile neutrinos by exploiting a set of kinematic observables which differ between the Dirac and Majorana cases. We find that the MVA method, compared to the more common CC method, can greatly enhance the discovery and discrimination limits. Two benchmark points with sterile neutrino mass m_N=20 GeV and 50 GeV are tested. For an integrated luminosity of 3000 fb"-"1, sterile neutrinos can be found with 5σ significance if heavy-to-light neutrino mixings vertical stroke U_N_e vertical stroke "2∝ vertical stroke U_N_μ vertical stroke "2∝10"-"6, while Majorana vs. Dirac discrimination can be reached if at least one of the mixings is of order 10"-"5.
Neutrino masses from SUSY breaking in radiative seesaw models
International Nuclear Information System (INIS)
Figueiredo, Antonio J.R.
2015-01-01
Radiatively generated neutrino masses (m ν ) are proportional to supersymmetry (SUSY) breaking, as a result of the SUSY non-renormalisation theorem. In this work, we investigate the space of SUSY radiative seesaw models with regard to their dependence on SUSY breaking (SUSY). In addition to contributions from sources of SUSY that are involved in electroweak symmetry breaking (SUSY EWSB contributions), and which are manifest from left angle F H † right angle = μ left angle anti H right angle ≠ 0 and left angle D right angle = g sum H left angle H † x H H right angle ≠ 0, radiatively generated m ν can also receive contributions from SUSY sources that are unrelated to EWSB (SUSY EWS contributions). We point out that recent literature overlooks pure-SUSY EWSB contributions (∝ μ/M) that can arise at the same order of perturbation theory as the leading order contribution from SUSY EWS . We show that there exist realistic radiative seesaw models in which the leading order contribution to m ν is proportional to SUSY EWS . To our knowledge no model with such a feature exists in the literature. We give a complete description of the simplest model topologies and their leading dependence on SUSY. We show that in one-loop realisations LLHH operators are suppressed by at least μ m soft /M 3 or m soft 2 /M 3 . We construct a model example based on a oneloop type-II seesaw. An interesting aspect of these models lies in the fact that the scale of soft-SUSY effects generating the leading order m ν can be quite small without conflicting with lower limits on the mass of new particles. (orig.)
Effect of atmospheric flux uncertainties on the determination of the neutrino mass hierarchy
Directory of Open Access Journals (Sweden)
Sandroos Joakim
2016-01-01
Full Text Available 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.
Experimental conditions for determination of the neutrino mass hierarchy with reactor antineutrinos
Directory of Open Access Journals (Sweden)
Myoung Youl Pac
2016-01-01
Full Text Available This article reports the optimized experimental requirements to determine neutrino mass hierarchy using electron antineutrinos (ν¯e generated in a nuclear reactor. The features of the neutrino mass hierarchy can be extracted from the |Δm312| and |Δm322| 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 sin22θ13=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 ν¯e. These results will be helpful for setting up an experiment to determine the neutrino mass hierarchy, which is an important problem in neutrino physics.
Neutrino mass and oscillation angle phenomena within the asymmetric left-right models
International Nuclear Information System (INIS)
Boyarkin, O.; Rein, D.
1994-07-01
The light and heavy Majorana neutrinos which appear naturally in SU(2) L x SU(2) R x U(1) B-L model are investigated. The exact solutions are presented for the system of two neutrinos with multipole moments propagating through magnetic and matter fields. The cross section of the reaction e - e - → W - k W - n calculated and its dependence on the mass of the right-handed neutrino and the oscillation angle is investigated. The process e + e - → W + k W - n is also included in our analysis. (author). 26 refs, 9 figs
Barenboim, G.
2014-12-10
The Standard Model has been incredibly successful in predicting the outcome of almost all the experiments done up so far. In it, neutrinos are mass-less. However, in recent years we have accumulated evidence pointing to tiny masses for the neutrinos (as compared to the charged leptons). These masses allow neutrinos to change their flavour and oscillate. In these lectures I review the properties of neutrinos in and beyond the Standard Model.
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.
Neutrino masses and b - τ unification in the supersymmetric standard model
International Nuclear Information System (INIS)
Vissani, F.; Smirnov, A.Yu.
1994-05-01
There are several indications that the Majorana masses of the right-handed neutrino components, M R , are at the intermediate scale: M R ∼ (10 10 - 10 12 ) GeV or even lighter. The renormalization effects due to large Yukawa couplings of neutrinos from region of momenta M R G are studied in the supersymmetric standard model. It is shown that neutrino renormalization effect can increase the m b /m τ ratio up to (10/15)%. This strongly disfavors m b - m τ unification for low values of tan β s . Lower bound on M R and tan β from the b - τ unification condition were found. The implications of the results to the see-saw mechanism of the neutrino mass generation are discussed. (author). 17 refs, 4 figs
Unveiling ν secrets with cosmological data: Neutrino masses and mass hierarchy
Vagnozzi, Sunny; Giusarma, Elena; Mena, Olga; Freese, Katherine; Gerbino, Martina; Ho, Shirley; Lattanzi, Massimiliano
2017-12-01
Using some of the latest cosmological data sets publicly available, we derive the strongest bounds in the literature on the sum of the three active neutrino masses, Mν, within the assumption of a background flat Λ CDM cosmology. In the most conservative scheme, combining Planck cosmic microwave background temperature anisotropies and baryon acoustic oscillations (BAO) data, as well as the up-to-date constraint on the optical depth to reionization (τ ), the tightest 95% confidence level upper bound we find is Mν0.06 eV from oscillations data would raise the quoted upper bounds by O (0.1 σ ) and would not affect our conclusions.
Neutrino Masses with Inverse Hierarchy from Broken $L_{e}-L_{\\mu}-L_{\\tau}$: a Reappraisal
Altarelli, Guido; Altarelli, Guido; Franceschini, Roberto
2006-01-01
We discuss a class of models of neutrino masses and mixings with inverse hierarchy based on a broken U(1)_F flavour symmetry with charge L_e-L_\\mu-L_\\tau. The symmetry breaking sector receives separate contributions from flavon vev breaking terms and from soft mass breaking in the right handed Majorana sector. The model is able to reproduce in a natural way all observed features of the charged lepton mass spectrum and of neutrino masses and mixings (even with arbitrarily small \\theta_{13}), with the exception of a moderate fine tuning which is needed to accomodate the observed small value of r = Delta m^2_{sol} / Delta m^2_{atm}.
Insights into neutrino decoupling gleaned from considerations of the role of electron mass
Grohs, E.; Fuller, George M.
2017-10-01
We present calculations showing how electron rest mass influences entropy flow, neutrino decoupling, and Big Bang Nucleosynthesis (BBN) in the early universe. To elucidate this physics and especially the sensitivity of BBN and related epochs to electron mass, we consider a parameter space of rest mass values larger and smaller than the accepted vacuum value. Electromagnetic equilibrium, coupled with the high entropy of the early universe, guarantees that significant numbers of electron-positron pairs are present, and dominate over the number of ionization electrons to temperatures much lower than the vacuum electron rest mass. Scattering between the electrons-positrons and the neutrinos largely controls the flow of entropy from the plasma into the neutrino seas. Moreover, the number density of electron-positron-pair targets can be exponentially sensitive to the effective in-medium electron mass. This entropy flow influences the phasing of scale factor and temperature, the charged current weak-interaction-determined neutron-to-proton ratio, and the spectral distortions in the relic neutrino energy spectra. Our calculations show the sensitivity of the physics of this epoch to three separate effects: finite electron mass, finite-temperature quantum electrodynamic (QED) effects on the plasma equation of state, and Boltzmann neutrino energy transport. The ratio of neutrino to plasma-component energy scales manifests in Cosmic Microwave Background (CMB) observables, namely the baryon density and the radiation energy density, along with the primordial helium and deuterium abundances. Our results demonstrate how the treatment of in-medium electron mass (i.e., QED effects) could translate into an important source of uncertainty in extracting neutrino and beyond-standard-model physics limits from future high-precision CMB data.
Insights into neutrino decoupling gleaned from considerations of the role of electron mass
Directory of Open Access Journals (Sweden)
E. Grohs
2017-10-01
Full Text Available We present calculations showing how electron rest mass influences entropy flow, neutrino decoupling, and Big Bang Nucleosynthesis (BBN in the early universe. To elucidate this physics and especially the sensitivity of BBN and related epochs to electron mass, we consider a parameter space of rest mass values larger and smaller than the accepted vacuum value. Electromagnetic equilibrium, coupled with the high entropy of the early universe, guarantees that significant numbers of electron–positron pairs are present, and dominate over the number of ionization electrons to temperatures much lower than the vacuum electron rest mass. Scattering between the electrons–positrons and the neutrinos largely controls the flow of entropy from the plasma into the neutrino seas. Moreover, the number density of electron–positron-pair targets can be exponentially sensitive to the effective in-medium electron mass. This entropy flow influences the phasing of scale factor and temperature, the charged current weak-interaction-determined neutron-to-proton ratio, and the spectral distortions in the relic neutrino energy spectra. Our calculations show the sensitivity of the physics of this epoch to three separate effects: finite electron mass, finite-temperature quantum electrodynamic (QED effects on the plasma equation of state, and Boltzmann neutrino energy transport. The ratio of neutrino to plasma–component energy scales manifests in Cosmic Microwave Background (CMB observables, namely the baryon density and the radiation energy density, along with the primordial helium and deuterium abundances. Our results demonstrate how the treatment of in-medium electron mass (i.e., QED effects could translate into an important source of uncertainty in extracting neutrino and beyond-standard-model physics limits from future high-precision CMB data.
Precision electron-capture energy in {sup 202}Pb and its relevance for neutrino mass determination
Energy Technology Data Exchange (ETDEWEB)
Welker, A. [CERN, Geneva (Switzerland); Technische Universitaet Dresden, Dresden (Germany); Filianin, P. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Althubiti, N.A.S. [The University of Manchester, School of Physics and Astronomy, Manchester (United Kingdom); Atanasov, D.; Blaum, K.; Eliseev, S.; Kreim, S. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Cocolios, T.E. [The University of Manchester, School of Physics and Astronomy, Manchester (United Kingdom); KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven (Belgium); Herfurth, F.; Neidherr, D. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Lunney, D. [CSNSM-IN2P3-CNRS, Universite Paris-Sud, Orsay (France); Manea, V. [CERN, Geneva (Switzerland); Novikov, Yu. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Physics Faculty, St. Petersburg State University (Russian Federation); Rosenbusch, M.; Schweikhard, L.; Wienholtz, F. [Ernst-Moritz-Arndt-Universitaet, Institut fuer Physik, Greifswald (Germany); Wolf, R.N. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); The University of Sydney, ARC Centre of Excellence for Engineered Quantum Systems, Sydney (Australia); Zuber, K. [Technische Universitaet Dresden, Dresden (Germany)
2017-07-15
Within the framework of an extensive programme devoted to the search for alternative candidates for the neutrino mass determination, the atomic mass difference between {sup 202}Pb and {sup 202}Tl has been measured with the Penning trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN. The obtained value Q{sub EC} = 38.8(43) keV is three times more precise than the AME2012 value. While it will probably not lead to a replacement of {sup 163}Ho in modern experiments on the determination of the electron-neutrino mass, the electron capture in {sup 202}Pb would however allow a determination of the electron-neutrino mass on the few-eV level using a cryogenic micro-calorimeter. (orig.)
Neutrino mass, leptogenesis and FIMP dark matter in a U(1){sub B-L} model
Energy Technology Data Exchange (ETDEWEB)
Biswas, Anirban; Khan, Sarif [Harish-Chandra Research Institute, Allahabad (India); Homi Bhabha National Institute, Training School Complex, Mumbai (India); Choubey, Sandhya [Harish-Chandra Research Institute, Allahabad (India); Homi Bhabha National Institute, Training School Complex, Mumbai (India); AlbaNova University Center, Department of Theoretical Physics, School of Engineering Sciences, KTH Royal Institute of Technology, Stockholm (Sweden)
2017-12-15
The Standard Model (SM) is inadequate to explain the origin of tiny neutrino masses, the dark matter (DM) relic abundance and the baryon asymmetry of the Universe. In this work, to address all three puzzles, we extend the SM by a local U(1){sub B-L} gauge symmetry, three right-handed (RH) neutrinos for the cancellation of gauge anomalies and two complex scalars having non-zero U(1){sub B-L} charges. All the newly added particles become massive after the breaking of the U(1){sub B-L} symmetry by the vacuum expectation value (VEV) of one of the scalar fields φ{sub H}. The other scalar field, φ{sub DM}, which does not have any VEV, becomes automatically stable and can be a viable DM candidate. Neutrino masses are generated using the Type-I seesaw mechanism, while the required lepton asymmetry to reproduce the observed baryon asymmetry can be attained from the CP violating out of equilibrium decays of the RH neutrinos in TeV scale. More importantly within this framework, we study in detail the production of DM via the freeze-in mechanism considering all possible annihilation and decay processes. Finally, we find a situation when DM is dominantly produced from the annihilation of the RH neutrinos, which are at the same time also responsible for neutrino mass generation and leptogenesis. (orig.)
Neutrino mass, leptogenesis and FIMP dark matter in a U(1)_{B-L} model
Biswas, Anirban; Choubey, Sandhya; Khan, Sarif
2017-12-01
The Standard Model (SM) is inadequate to explain the origin of tiny neutrino masses, the dark matter (DM) relic abundance and the baryon asymmetry of the Universe. In this work, to address all three puzzles, we extend the SM by a local U(1)_{B-L} gauge symmetry, three right-handed (RH) neutrinos for the cancellation of gauge anomalies and two complex scalars having non-zero U(1)_{B-L} charges. All the newly added particles become massive after the breaking of the U(1)_{B-L} symmetry by the vacuum expectation value (VEV) of one of the scalar fields φ _H. The other scalar field, φ _DM, which does not have any VEV, becomes automatically stable and can be a viable DM candidate. Neutrino masses are generated using the Type-I seesaw mechanism, while the required lepton asymmetry to reproduce the observed baryon asymmetry can be attained from the CP violating out of equilibrium decays of the RH neutrinos in TeV scale. More importantly within this framework, we study in detail the production of DM via the freeze-in mechanism considering all possible annihilation and decay processes. Finally, we find a situation when DM is dominantly produced from the annihilation of the RH neutrinos, which are at the same time also responsible for neutrino mass generation and leptogenesis.
Determining the neutrino mass hierarchy with INO, T2K, NOvA and reactor experiments
International Nuclear Information System (INIS)
Ghosh, Anushree; Choubey, Sandhya; Thakore, Tarak
2013-01-01
The relatively large measured value of θ 13 has opened up the possibility of determining the neutrino mass hierarchy through earth matter effects. Amongst the current accelerator experiments only NOvA has a long enough baseline to observe earth matter effects. However, even NOvA is plagued with uncertainty on the knowledge of the true value of Δ CP which drastically reduces its sensitivity to the neutrino mass hierarchy. Earth matter effects in atmospheric neutrinos on the other hand is almost independent of δ CP . The 50 kton magnetized Iron CALorimeter at the India-based Neutrino Observatory (ICAL at the rate lNO) will be observing atmospheric neutrinos. The charge identification capability of this detector gives it an edge over others for mass hierarchy determination through observation of earth matter effects. We study in detail the neutrino mass hierarchy sensitivity of the data from this experiment simulated using the Nuance based generator developed for ICAL at the rate lNO and folded with the detector resolution and efficiencies obtained by the INO collaboration from a full detector Geant based simulation. The data from ICAL at the rate lNO is then combined with simulated of T2K, NOvA Double Chooz, RENO and Daya Bay experiments and a combined sensitivity study to the mass hierarchy performed. With 10 years of ICAL at the rate lNO data combined with T2K, NOvA and reactor data, one could get 2.8σ - 5σ discovery for the neutrino mass hierarchy depending on the true value of (θ23, θ13 and δ CP . (author)
International Nuclear Information System (INIS)
Roulet, E.
2001-01-01
A general overview of neutrino physics and astrophysics is given, starting with a historical account of the development of our understanding of neutrinos and how they helped to unravel the structure of the Standard Model. We discuss why it is so important to establish if neutrinos are massive and introduce the main scenarios to provide them a mass. The present bounds and the positive indications in favor of non-zero neutrino masses are discussed, including the recent results on atmospheric and solar neutrinos. The major role that neutrinos play in astrophysics and cosmology is illustrated. (author)
An upper limit on the $\\tau$ neutrino mass from three- and five-prong tau decays
Barate, R; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Pietrzyk, B; Casado, M P; Chmeissani, M; Comas, P; Crespo, J M; Delfino, M C; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Merino, G; Miquel, R; Mir, L M; Padilla, C; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Alemany, R; Becker, U; Bright-Thomas, P G; Casper, David William; Cattaneo, M; Cerutti, F; Dissertori, G; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Hansen, J B; Harvey, J; Janot, P; Jost, B; Lehraus, Ivan; Mato, P; Minten, Adolf G; Moneta, L; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rolandi, Luigi; Rousseau, D; Schlatter, W D; Schmitt, M; Schneider, O; Tejessy, W; Teubert, F; Tomalin, I R; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Rossignol, J M; Fearnley, Tom; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Boccali, T; Focardi, E; Parrini, G; Zachariadou, K; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Lynch, J G; O'Shea, V; Raine, C; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, E; Thomson, F; Buchmüller, O L; Dhamotharan, S; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Martin, E B; Moutoussi, A; Nash, J; Sedgbeer, J K; Spagnolo, P; Stacey, A M; Williams, M D; Ghete, V M; Girtler, P; Kneringer, E; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Buck, P G; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Sloan, Terence; Williams, M I; Giehl, I; Greene, A M; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Bujosa, G; Carr, J; Coyle, P; Diaconu, C A; Etienne, F; Leroy, O; Motsch, F; Payre, P; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Aleppo, M; Antonelli, M; Ragusa, F; Berlich, R; Blum, Walter; Büscher, V; Dietl, H; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Mannert, C; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Stenzel, H; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Chen, S; Choi, Y; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Höcker, A; Jacholkowska, A; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Schune, M H; Tournefier, E; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Rizzo, G; Sanguinetti, G; Sciabà, A; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Bryant, L M; Chambers, J T; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Konstantinidis, N P; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Brew, C A J; Cartwright, S L; Combley, F; Kelly, M S; Lehto, M H; Reeve, J; Thompson, L F; Affholderbach, K; Böhrer, A; Brandt, S; Cowan, G D; Grupen, Claus; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Charles, E; Elmer, P; Ferguson, D P S; Gao, Y; González, S; Greening, T C; Hayes, O J; Hu, H; Jin, S; McNamara, P A; Nachtman, J M; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Yamartino, J M; Zobernig, G
1998-01-01
A bound on the tau neutrino mass is established using the data collected from 1991 to 1995 at Ecm = M(Z) with the ALEPH detector. Two separate limits are derived by fitting the distribution of visible energy vs invariant mass in tau+ -> pi+ pi+ pi- nu and tau+ -> pi+ pi+ pi- pi- pi+ (pi0) nu decays. The two results are combined to obtain a 95 % confidence level upper limit of 18.2 MeV/c^2 on the mass of the tau neutrino.
Neutrino mass models and the implications of a non-zero reactor angle
International Nuclear Information System (INIS)
King, S.F.
2009-01-01
In this talk we survey some of the recent promising developments in the search for the theory behind neutrino mass and mixing, and indeed all fermion masses and mixing. The talk is organized in terms of a neutrino mass models decision tree according to which the answers to experimental questions provide sign posts to guide through the maze of theoretical models eventually towards a complete theory of flavour and unification. It is also discussed the theoretical implications of the measurement of non-zero reactor angle, as hinted at by recent experimental measurements.
Pais, Abraham; Jacob, Maurice; Olive, David I.; Atiyah, Michael F.
2005-09-01
Preface Peter Goddard; Dirac memorial address Stephen Hawking; 1. Paul Dirac: aspects of his life and work Abraham Pais; 2. Antimatter Maurice Jacob; 3. The monopole David Olive; 4. The Dirac equation and geometry Michael F. Atiyah.
Energy Technology Data Exchange (ETDEWEB)
Sobkow, W.; Blaut, A. [University of Wroclaw, Institute of Theoretical Physics, Wroclaw (Poland)
2016-05-15
In this paper, we analyze the theoretically possible scenario beyond the standard model in order to show how the presence of the exotic scalar, tensor, V + A weak interactions in addition to the standard vector-axial (V - A) ones may help to distinguish the Dirac from Majorana neutrinos in the elastic scattering of an (anti)neutrino beam off the unpolarized electrons in the relativistic limit. We assume that the incoming (anti)neutrino beam comes from the polarized muon decay at rest and is the left-right chiral superposition with assigned direction of the transversal spin polarization with respect to the production plane. Our analysis is carried out for the flavour (current) neutrino eigenstates. It means that the transverse neutrino polarization estimates are the same both for the Dirac and Majorana cases. We display that the azimuthal asymmetry in the angular distribution of recoil electrons is generated by the interference terms between the standard and exotic couplings, which are proportional to the transversal (anti)neutrino spin polarization and independent of the neutrino mass. This asymmetry for the Majorana neutrinos is larger than for the Dirac ones. We also indicate the possibility of utilizing the azimuthal asymmetry measurements to search for the new CP-violating phases. Our study is based on the assumption that the possible detector (running for 1 year) has the shape of a flat circular ring, while the intense neutrino source is located in the centre of the ring and polarized perpendicularly to the ring. In addition, the large low-threshold, real-time detector is able to measure with a high resolution both the polar angle and the azimuthal angle of outgoing electron momentum. Our analysis is model-independent and consistent with the current upper limits on the non-standard couplings. (orig.)
Disordered 2d quasiparticles in class D: Dirac fermions with random mass, and dirty superconductors
International Nuclear Information System (INIS)
Bocquet, M.; Serban, D.; Zirnbauer, M.R.
2000-01-01
Disordered noninteracting quasiparticles that are governed by a Majorana-type Hamiltonian -- prominent examples are dirty superconductors with broken time-reversal and spin-rotation symmetry, or the fermionic representation of the 2d Ising model with fluctuating bond strengths -- are called class D . In two dimensions, weakly disordered systems of this kind may possess a metallic phase beyond the insulating phases expected for strong disorder. We show that the 2d metal phase emanates from the free Majorana fermion point, in the direction of the RG trajectory of a perturbed WZW model. To establish this result, we develop a supersymmetric extension of the method of nonabelian bosonization. On the metallic side of the metal-insulator transition, the density of states becomes nonvanishing at zero energy, by a mechanism akin to dynamical mass generation. This feature is explored in a model of N species of disordered Dirac fermions, via the mapping on a nonlinear sigma model, which encapsulates a Z 2 spin degree of freedom. We compute the density of states in a finite system, and obtain agreement with the random-matrix prediction for class D , in the ergodic limit. Vortex disorder, which is a relevant perturbation at the free-fermion point, changes the density of states at low energy and suppresses the local Z 2 degree of freedom, thereby leading to a different symmetry class, BD
Energy Technology Data Exchange (ETDEWEB)
Lopez-Pavon, J. [SISSA and INFN - sezione di Trieste, via Bonomea 265, 34136 Trieste (Italy); Molinaro, E. [CP-Origins and Danish Institute for Advanced Study, University of Southern Denmark,Campusvej 55, DK-5230 Odense M (Denmark); Petcov, S.T. [SISSA and INFN - sezione di Trieste, via Bonomea 265, 34136 Trieste (Italy); Kavli IPMU (WPI), University of Tokyo, 5-1-5 Kashiwanoha, 277-8583 Kashiwa (Japan)
2015-11-05
We perform a detailed analysis of the one-loop corrections to the light neutrino mass matrix within low scale type I seesaw extensions of the Standard Model and their implications in experimental searches for neutrinoless double beta decay. We show that a sizable contribution to the effective Majorana neutrino mass from the exchange of heavy Majorana neutrinos is always possible, provided one requires a fine-tuned cancellation between the tree-level and one-loop contribution to the light neutrino masses. We quantify the level of fine-tuning as a function of the seesaw parameters and introduce a generalisation of the Casas-Ibarra parametrization of the neutrino Yukawa matrix, which easily allows to include the one-loop corrections to the light neutrino masses.
Remark on natural models of neutrinos
International Nuclear Information System (INIS)
Fujikawa, Kazuo
2005-01-01
We comment on what 't Hooft's naturalness argument implies with regard to a minimal extension of the Standard Model that incorporates right-handed neutrinos with generic mass terms. If this Lagrangian is taken as that of a low energy effective theory, the idea of pseudo-Dirac neutrinos with very small masses is consistent with 't Hooft's naturalness argument. This argument is based on the observation that the right-handed components of neutrinos in the massless limit exhibit an extra enhanced symmetry which is absent in other charged fermions. This enhanced symmetry is reminiscent of the Nambu-Goldstone fermions associated with spontaneously broken supersymmetry. The conventional seesaw scenario gives another natural solution if the ultra-heavy right-handed neutrinos are integrated out in the formulation of a low energy effective theory. (author)
Renormalization-group equations of neutrino masses and flavor mixing parameters in matter
Xing, Zhi-zhong; Zhou, Shun; Zhou, Ye-Ling
2018-05-01
We borrow the general idea of renormalization-group equations (RGEs) to understand how neutrino masses and flavor mixing parameters evolve when neutrinos propagate in a medium, highlighting a meaningful possibility that the genuine flavor quantities in vacuum can be extrapolated from their matter-corrected counterparts to be measured in some realistic neutrino oscillation experiments. Taking the matter parameter a≡ 2√{2}{G}F{N}_eE to be an arbitrary scale-like variable with N e being the net electron number density and E being the neutrino beam energy, we derive a complete set of differential equations for the effective neutrino mixing matrix V and the effective neutrino masses {\\tilde{m}}_i (for i = 1 , 2 , 3). Given the standard parametrization of V , the RGEs for {{\\tilde{θ}}_{12}, {\\tilde{θ}}_{13}, {\\tilde{θ}}_{23}, \\tilde{δ}} in matter are formulated for the first time. We demonstrate some useful differential invariants which retain the same form from vacuum to matter, including the well-known Naumov and Toshev relations. The RGEs of the partial μ- τ asymmetries, the off-diagonal asymmetries and the sides of unitarity triangles of V are also obtained as a by-product.
Neutrino mass bounds from neutrinoless double beta-decays and ...
Indian Academy of Sciences (India)
2016-01-21
Jan 21, 2016 ... CMD model. In addition, we explore the interacting neutrino dark-energy model, where the ... This decay has a small energy release (E0 ≃ 18.6 keV) and a convenient lifetime (T1/2 = 12.3 yr). As the ...... Research Programme funded by the Korean Ministry of Science, ICT and Future Planning. (Grant No.
Theoretical aspects of neutrino mass and lepton flavour violation
Indian Academy of Sciences (India)
We consider lepton ﬂavour violation (LFV) in the charged lepton sector both from the bottom-up effective Lagrangian approach and from the top-down approach via various case studies that have been analysed. The implications for LFV studies at the LHC is brieﬂy discussed. Finally the nature of LFV in the neutrino sector is ...
Texture zero neutrino models and their connection with resonant leptogenesis
Achelashvili, Avtandil; Tavartkiladze, Zurab
2018-04-01
Within the low scale resonant leptogenesis scenario, the cosmological CP asymmetry may arise by radiative corrections through the charged lepton Yukawa couplings. While in some cases, as one expects, decisive role is played by the λτ coupling, we show that in specific neutrino textures only by inclusion of the λμ the cosmological CP violation is generated at 1-loop level. With the purpose to relate the cosmological CP violation to the leptonic CP phase δ, we consider an extension of MSSM with two right handed neutrinos (RHN), which are degenerate in mass at high scales. Together with this, we first consider two texture zero 3 × 2 Dirac Yukawa matrices of neutrinos. These via see-saw generated neutrino mass matrices augmented by single ΔL = 2 dimension five (d = 5) operator give predictive neutrino sectors with calculable CP asymmetries. The latter is generated through λμ,τ coupling(s) at 1-loop level. Detailed analysis of the leptogenesis is performed. We also revise some one texture zero Dirac Yukawa matrices, considered earlier, and show that addition of a single ΔL = 2, d = 5 entry in the neutrino mass matrices, together with newly computed 1-loop corrections to the CP asymmetries, give nice accommodation of the neutrino sector and desirable amount of the baryon asymmetry via the resonant leptogenesis even for rather low RHN masses (∼few TeV-107 GeV).
From the trees to the forest: a review of radiative neutrino mass models
Cai, Yi; Herrero García, Juan; Schmidt, Michael A.; Vicente, Avelino; Volkas, Raymond R.
2017-12-01
A plausible explanation for the lightness of neutrino masses is that neutrinos are massless at tree level, with their mass (typically Majorana) being generated radiatively at one or more loops. The new couplings, together with the suppression coming from the loop factors, imply that the new degrees of freedom cannot be too heavy (they are typically at the TeV scale). Therefore, in these models there are no large mass hierarchies and they can be tested using different searches, making their detailed phenomenological study very appealing. In particular, the new particles can be searched for at colliders and generically induce signals in lepton-flavor and lepton-number violating processes (in the case of Majorana neutrinos), which are not independent from reproducing correctly the neutrino masses and mixings. The main focus of the review is on Majorana neutrinos. We order the allowed theory space from three different perspectives: (i) using an effective operator approach to lepton number violation, (ii) by the number of loops at which the Weinberg operator is generated, (iii) within a given loop order, by the possible irreducible topologies. We also discuss in more detail some popular radiative models which involve qualitatively different features, revisiting their most important phenomenological implications. Finally, we list some promising avenues to pursue.
Directory of Open Access Journals (Sweden)
Altuğ Arda
2017-01-01
Full Text Available We find the exact bound state solutions and normalization constant for the Dirac equation with scalar-vector-pseudoscalar interaction terms for the generalized Hulthén potential in the case where we have a particular mass function m(x. We also search the solutions for the constant mass where the obtained results correspond to the ones when the Dirac equation has spin and pseudospin symmetry, respectively. After giving the obtained results for the nonrelativistic case, we search then the energy spectra and corresponding upper and lower components of Dirac spinor for the case of PT-symmetric forms of the present potential.
Neutrino masses and flavor mixing in the extended double Seesaw model with two texture zeros
International Nuclear Information System (INIS)
Hu, Li-Jun; Dulat, Sayipjamal; Ablat, Abduleziz
2011-01-01
We study the light neutrino mass matrix in the extended double Seesaw model (EDSM), and as a result we get its general form. Also we demonstrate that conventional type-I and double seesaw mechanisms can be regarded as two special cases. We analyze the structure of the 9 x 9 neutrino mass matrix in this scenario, and surprisingly we find that EDSM will degenerate to a conventional type-I seesaw mechanism when M R = M S M μ -1 M S T holds exactly. Considering two simple ansaetze in two texture zeros for its 3 x 3 submatrices, we calculate the neutrino masses and flavor mixing angles, in which the θ 13 is a nonzero large angle. (orig.)
International Nuclear Information System (INIS)
Le Bas, P.A.
1984-01-01
Data on the mass of the anti-neutrino determined via electrostatic measurements of tritium beta-decay are assessed. Relativistic calculations concerning the finite mass of the electron anti-neutrino and the recoil of the nucleus, are given for the theoretical end-point spectrum of tritium beta-decay. The specifications are given for an electrostatic Spherical Retarding Beta-Spectrometer, and an electrostatic Cylindrical Mirror Analyser, both used in the tritium beta-decay experiment. The electrostatic measurements lead to a value of less than 50 ev (90% C.L.) for the electron anti-neutrino mass. These results are discussed in terms of the resolution of the electrostatic equipment and the Monte Carlo simulations of the data collection. (UK)
Beta Decay in the Field of an Electromagnetic Wave and Experiments on Measuring the Neutrino Mass
International Nuclear Information System (INIS)
Dorofeev, O.F.; Lobanov, A.E.
2005-01-01
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'
Beyond the standard seesaw neutrino masses from Kahler operators and broken supersymmetry
Brignole, Andrea; Rossi, Anna
2010-01-01
We investigate supersymmetric scenarios in which neutrino masses are generated by effective d=6 operators in the Kahler potential, rather than by the standard d=5 superpotential operator. First, we discuss some general features of such effective operators, also including SUSY-breaking insertions, and compute the relevant renormalization group equations. Contributions to neutrino masses arise at low energy both at the tree level and through finite threshold corrections. In the second part we present simple explicit realizations in which those Kahler operators arise by integrating out heavy SU(2)_W triplets, as in the type II seesaw. Distinct scenarios emerge, depending on the mechanism and the scale of SUSY-breaking mediation. In particular, we propose an appealing and economical picture in which the heavy seesaw mediators are also messengers of SUSY breaking. In this case, strong correlations exist among neutrino parameters, sparticle and Higgs masses, as well as lepton flavour violating processes. Hence, thi...
Nonlinear Dynamics of the Cosmic Neutrino Background
Inman, Derek
At least two of the three neutrino species are known to be massive, but their exact masses are currently unknown. Cosmic neutrinos decoupled from the rest of the primordial plasma early on when the Universe was over a billion times hotter than it is today. These relic particles, which have cooled and are now non-relativistic, constitute the Cosmic Neutrino Background and permeate the Universe. While they are not observable directly, their presence can be inferred by measuring the suppression of the matter power spectrum. This suppression is a linear effect caused by the large thermal velocities of neutrinos, which prevent them from collapsing gravitationally on small scales. Unfortunately, it is difficult to measure because of degeneracies with other cosmological parameters and biases arising from the fact that we typically observe point-like galaxies rather than a continous matter field. It is therefore important to look for new effects beyond linear suppression that may be more sensitive to neutrinos. This thesis contributes to the understanding of the nonlinear dynamics of the cosmological neutrino background in the following ways: (i) the development of a new injection scheme for neutrinos in cosmological N-body simulations which circumvents many issues associated with simulating neutrinos at large redshifts, (ii) the numerical study of the relative velocity field between cold dark matter and neutrinos including its reconstruction from density fields, (iii) the theoretical description of neutrinos as a dispersive fluid and its use in modelling the nonlinear evolution of the neutrino density power spectrum, (iv) the derivation of the dipole correlation function using linear response which allows for the Fermi-Dirac velocity distribution to be properly included, and (v) the numerical study and detection of the dipole correlation function in the TianNu simulation. In totality, this thesis is a comprehensive study of neutrino density and velocity fields that may
Verma, Surender; Bhardwaj, Shankita
2018-05-01
We have investigated a possible connection between the Majorana phases and geometric parameters of Majorana unitarity triangle (MT) in two-texture zero neutrino mass matrix. Such analytical relations can, also, be obtained for other theoretical models viz. hybrid textures, neutrino mass matrix with vanishing minors and have profound implications for geometric description of C P violation. As an example, we have considered the two-texture zero neutrino mass model to obtain a relation between Majorana phases and MT parameters that may be probed in various lepton number violating processes. In particular, we find that Majorana phases depend on only one of the three interior angles of the MT in each class of two-texture zero neutrino mass matrix. We have also constructed the MT for class A , B , and C neutrino mass matrices. Nonvanishing areas and nontrivial orientations of these Majorana unitarity triangles indicate nonzero C P violation as a generic feature of this class of mass models.
Neutrino 2004: Collection of Presentations
International Nuclear Information System (INIS)
2004-01-01
The scientific program covers the latest developments in neutrino physics, astrophysics and related topics through a set of invited talks and 2 poster sessions. The following issues are addressed: - solar neutrinos, - atmospheric neutrinos, - short and long baseline experiments, - neutrino oscillations, - double beta decay, - direct neutrino mass limits, - theory for neutrino masses, neutrino telescopes and ultra-high energy neutrinos, - dark matter searches, - neutrino in astrophysics and cosmology, and - future projects beams and experiments
Neutrino 2004: Collection of Presentations
Energy Technology Data Exchange (ETDEWEB)
NONE
2004-07-01
The scientific program covers the latest developments in neutrino physics, astrophysics and related topics through a set of invited talks and 2 poster sessions. The following issues are addressed: - solar neutrinos, - atmospheric neutrinos, - short and long baseline experiments, - neutrino oscillations, - double beta decay, - direct neutrino mass limits, - theory for neutrino masses, neutrino telescopes and ultra-high energy neutrinos, - dark matter searches, - neutrino in astrophysics and cosmology, and - future projects beams and experiments.
Link, Jonathan M
2018-01-01
Neutrinos have a smaller mass than any other known particle and are the subject of intense recent studies, as well as this book. The author provides a coherent introduction to the necessary theoretical background and experimental methods used by modern neutrino physicists. It’s designed as a one-stop reference addressing what is currently known about the neutrino hypothesis, discovery of the neutrino, theory of weak interactions, solar neutrino puzzle, and neutrino oscillation. It then gives a detailed account of practical approaches for study of precision oscillations, neutrino mass and other neutrino properties, sterile neutrinos, and neutrino messengers from space and Earth’s interior.
Meson exchange second class currents and the neutrino mass in the muon capture by light nuclei
International Nuclear Information System (INIS)
Katkhat, Ch.L.
1988-01-01
Influence of the Kubodera-Delorme-Rho model parameters (ζ and ξ), the scalar form factor (F s ) and the muonic neutrino rest mass (m νμ ) on the asymmetry coefficient (α μν ) of neutrino emission with respect to the muon spin orientation in the muon capture by light nuclei is analyzed. It is shown, that the mass m νμ , the parameters of ζ and ξ, and the form factor F s may be estimated by studying the coefficient α μν in O -> O, Gamov-Teller, and mixed transitions, respectively
Magic neutrino mass matrix and the Bjorken-Harrison-Scott parameterization
International Nuclear Information System (INIS)
Lam, C.S.
2006-01-01
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 U e3 , in a form discussed recently by Bjorken, Harrison, and Scott
The mass of the electron neutrino and electron capture in 163Ho
International Nuclear Information System (INIS)
Yasumi, S.; Rajasekaran, G.; Ando, M.; Ochiai, F.; Ikeda, H.; Ohta, T.; Stefan, P.M.; Maruyama, M.; Nashimoto, N.; Fujioka, M.; Ishii, K.; Shinozuka, T.; Sera, K.; Omori, T.; Izawa, G.; Yagi, M.; Masumoto, K.; Shima, K.
1983-01-01
To determine the mass of the electron neutrino, electron capture in 163 Ho was studied. From the intensity of M X-rays and the total number of 163 Ho atoms in a source, as determined by the PIXE method, the partial M-capture half life of 163 Ho was estimated to be (4.5 +- 1.5) x 10 4 yr. A relation between the Q-value of 163 Ho and the mass of the electron neutrino was obtained. (orig.)
Sterile neutrinos with eV masses in cosmology — How disfavoured exactly?
DEFF Research Database (Denmark)
Hamann, Jan; Hannestad, Steen; Raffelt, G.G.
2011-01-01
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...... be circumvented by a small νe 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....
External meeting: KATRIN - direct measurement of neutrino masses with sub-eV sensitivity
2007-01-01
GENEVA UNIVERSITY - ECOLE DE PHYSIQUE Département de physique nucléaire et corspusculaire 24, Quai Ernest-Ansermet 1211 GENEVE 4 - Tél : 022 379 62 73 - Fax: 022 379 69 92 Wednesday 18 April 2007 PARTICLE PHYSICS SEMINAR at 17:00 - Stückelberg Auditorium KATRIN - direct measurement of neutrino masses with sub-eV sensitivity by Prof. Guido Drexlin, Karlsruhe Institute of Technology KIT The major scientific objective of the international Karlsruhe Tritum Neutrino (KATRIN) Experiment is the model independent measurement of the electron neutrino mass in tritium beta decay with a sensitivity of 200 meV. In the cosmological context, this allows an investigation of whether massive relic neutrinos left over from the Big Bang play a specific role as hot dark matter in the evolution of large scale structures of the universe. In particle physics KATRIN will allow for discrimination between different neutrino mass models (either of quasi-degenerate or hierarchical pattern).The key components of KATRIN comprise...
Neutrino masses in the SO(10) model with intermediate stage of the symmetry breaking
International Nuclear Information System (INIS)
Svetovoj, V.B.
1982-01-01
An effect for the neutrino masses of an intermediate stage in the symmetry spontaneous breaking, different from SU(5), is investigated in some detail for the SO(1O) model. There are two possibilities depending on the composition of the Higgs sector: i) msub(ν) approximately msub(f)(Msub(W)/Msub(1)); ii) msub(ν) approximately msub(f)sub(b)/Msub(1))(M/Msub(1)), where M, M 1 and Msub) are the scales of the breaking of the original SO(10) simmetry, the intermediate symmetry, and the standard SUsub(c)(3)xSUsub(L)(2)xU(1) symmetry, respectively, and msub(f) is a typical fermion mass. It as shown that a Majorana mass of the right neutrino (νsub(R)) of a purely loop origin would result in a too large mass of the usual neutrinos, so a tree-graph contribution to the mass of νsub(R) is necessary. Numerical estimates for the neutrino masses are discussed [ru
Neutrino masses in an SO(10) model with an intermediate stage of symmetry breaking
International Nuclear Information System (INIS)
Svetovoi, V.B.
1982-01-01
The effect on neutrino masses of an intermediate stage in symmetry breaking different from SU(5) is investigated in detail for the SO(10) model. There are two possibilities depending on the contents of the Higgs sector: i) m/sub ν/approx.m/sub f/(M/sub W//M 1 ); ii) m/sub ν/approx.m/sub f/(M/sub W//M 1 )(M/M 1 ), where M, M 1 and M/sub W/ are the scales of the breaking of the original SO(10) symmetry, the intermediate symmetry, and the standard SU/sub c/(3) x SU/sub L/(2) x U(1) symmetry, respectively, and m/sub f/ is a typical fermion mass. It is shown that a Majorana mass of the right-handed-neutrino (ν/sub R/) of a purely loop origin would result in too large a mass of the usual neutrinos, so a tree-graph contribution to the mass of ν/sub R/ is necessary. Numerical estimates for the neutrino masses are discussed
Determination of neutrino mass hierarchy and θ13 with a remote detector of reactor antineutrinos
International Nuclear Information System (INIS)
Learned, John G.; Pakvasa, Sandip; Dye, Stephen T.; Svoboda, Robert C.
2008-01-01
We describe a method for determining the hierarchy of the neutrino mass spectrum and θ 13 through remote detection of electron antineutrinos from a nuclear reactor. This method utilizing a single, 10-kiloton scintillating liquid detector at a distance of 49-63 kilometers from the reactor complex measures mass-squared differences involving ν 3 with a one(ten)-year exposure provided sin 2 (2θ 13 )>0.05(0.02). Our technique applies the Fourier transform to the event rate as a function of neutrino flight distance over neutrino energy. Sweeping a relevant range of δm 2 resolves separate spectral peaks for δm 2 31 and δm 2 32 . For normal (inverted) hierarchy |δm 2 31 | is greater (lesser) than |δm 2 32 |. This robust determination requires a detector energy resolution of 3.5%/√(E).
Gravitational wave generated by mass ejection in protoneutron star neutrino burst
International Nuclear Information System (INIS)
Almeida, L. G.; Rodrigues, H.; Portes, D. JR.; Duarte, S. B.
2010-01-01
In this work we discuss the mechanism of mass ejection in protoneutron stars induced by diffusion of neutrinos. A dynamical calculation is employed in order to determine the amount of matter ejected and the properties of the remnant compact object [1]. The equations of state of this supra-nuclear regime [2] is properly linked with others describing the different sub-nuclear regimes of density [3, 4, 5]. For specified initial configurations of the protoneutron star, we solve numerically the set of equations of motion together with a schematic treatment of the neutrino transport through the dense stellar medium. We investigate the gravitational waves production accompanying the mass ejection induced by the neutrino burst. It is estimated the gravitational wave intensity and the detection of such wave by the existing detector or near future project for this purpose is discussed.
Earth matter effects at very long baselines and the neutrino mass hierarchy
International Nuclear Information System (INIS)
Gandhi, Raj; Ghoshal, Pomita; Goswami, Srubabati; Mehta, Poonam; Sankar, S. Uma
2006-01-01
We study matter effects which arise in the muon neutrino oscillation and survival probabilities relevant to atmospheric neutrino and very long baseline (>4000 Km) beam experiments. The interrelations between the three probabilities P μe , P μτ , and P μμ are examined. It is shown that large and observable sensitivity to the neutrino mass hierarchy can be present in P μμ and P μτ . We emphasize that at baselines >7000 Km, matter effects in P μτ are important under certain conditions and can be large. The muon survival rates in experiments with very long baselines thus depend on matter effects in both P μτ and P μe . We also indicate where these effects provide sensitivity to θ 13 and identify ranges of energies and baselines where this sensitivity is maximum. The effect of parameter degeneracies in the three probabilities at these baselines and energies is studied in detail and large parts of the parameter space are identified which are free from these degeneracies. In the second part of the paper, we focus on using the matter effects studied in the first part as a means of determining the mass hierarchy via atmospheric neutrinos. Realistic event rate calculations are performed for a charge discriminating 100 kT iron calorimeter which demonstrate the possibility of realizing this very important goal in neutrino physics. It is shown that for atmospheric neutrinos, a careful selection of energy and baseline ranges is necessary in order to obtain a statistically significant signal, and that the effects are largest in bins where matter effects in both P μe and P μτ combine constructively. Under these conditions, up to a 4σ signal for matter effects is possible (for Δ 31 >0) within a time scale appreciably shorter than the one anticipated for neutrino factories
Fully constrained Majorana neutrino mass matrices using Σ(72 x 3)
Energy Technology Data Exchange (ETDEWEB)
Krishnan, R.; Harrison, P.F. [Warwick Univ., Coventry (United Kingdom); Scott, W.G. [Rutherford Appleton Laboratory, Chilton, Didcot (United Kingdom)
2018-01-15
In 2002, two neutrino mixing ansatze having trimaximally mixed middle (ν{sub 2}) columns, namely tri-chi-maximal mixing (TχM) and tri-phi-maximal mixing (TφM), were proposed. In 2012, it was shown that TχM with χ = ± (π)/(16) as well as TφM with φ = ± (π)/(16) leads to the solution, sin{sup 2} θ{sub 13} = (2)/(3) sin{sup 2} (π)/(16), consistent with the latest measurements of the reactor mixing angle, θ{sub 13}. To obtain TχM{sub (χ=±(π)/(16))} and TφM{sub (φ=±(π)/(16))}, the type I see-saw framework with fully constrained Majorana neutrino mass matrices was utilised. These mass matrices also resulted in the neutrino mass ratios, m{sub 1}: m{sub 2}: m{sub 3} = ((2+√2))/(1+√(2(2+√2))): 1: ((2+√2))/(-1+√(2(2+√2))). In this paper we construct a flavour model based on the discrete group Σ(72 x 3) and obtain the aforementioned results. A Majorana neutrino mass matrix (a symmetric 3 x 3 matrix with six complex degrees of freedom) is conveniently mapped into a flavon field transforming as the complex six-dimensional representation of Σ(72 x 3). Specific vacuum alignments of the flavons are used to arrive at the desired mass matrices. (orig.)
Sterile neutrinos with eV masses in cosmology — How disfavoured exactly?
International Nuclear Information System (INIS)
Hamann, Jan; Hannestad, Steen; Raffelt, Georg G.; Wong, Yvonne Y.Y.
2011-01-01
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 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
International Nuclear Information System (INIS)
Ishitsuka, Masaki; Kajita, Takaaki; Minakata, Hisakazu; Nunokawa, Hiroshi
2005-01-01
We explore the possibility of the simultaneous determination of neutrino mass hierarchy and the CP violating phase by using two identical detectors placed at different baseline distances. We focus on a possible experimental setup using a neutrino beam from the J-PARC facility in Japan with a beam power of 4 MW and megaton (Mton)-class water Cherenkov detectors, one placed in Kamioka and the other somewhere in Korea. We demonstrate, under reasonable assumptions of systematic uncertainties, that the two-detector complex with each fiducial volume of 0.27 Mton has a potential of resolving the neutrino mass hierarchy up to sin 2 2θ 13 >0.03 (0.055) at 2σ (3σ) C.L. for any values of δ and at the same time has the sensitivity to CP violation by 4+4 years running of ν e and ν e appearance measurement. The significantly enhanced sensitivity is due to clean detection of the modulation of the neutrino energy spectrum, which is enabled by the cancellation of systematic uncertainties between two identical detectors which receive the neutrino beam with the same energy spectrum in the absence of oscillations
From high-scale leptogenesis to low-scale one-loop neutrino mass generation
Zhou, Hang; Gu, Pei-Hong
2018-02-01
We show that a high-scale leptogenesis can be consistent with a low-scale one-loop neutrino mass generation. Our models are based on the SU(3)c × SU(2)L × U(1)Y × U(1) B - L gauge groups. Except a complex singlet scalar for the U(1) B - L symmetry breaking, the other new scalars and fermions (one scalar doublet, two or more real scalar singlets/triplets and three right-handed neutrinos) are odd under an unbroken Z2 discrete symmetry. The real scalar decays can produce an asymmetry stored in the new scalar doublet which subsequently decays into the standard model lepton doublets and the right-handed neutrinos. The lepton asymmetry in the standard model leptons then can be partially converted to a baryon asymmetry by the sphaleron processes. By integrating out the heavy scalar singlets/triplets, we can realize an effective theory to radiatively generate the small neutrino masses at the TeV scale. Furthermore, the lightest right-handed neutrino can serve as a dark matter candidate.
Sum rules for neutrino oscillations
International Nuclear Information System (INIS)
Kobzarev, I.Yu.; Martemyanov, B.V.; Okun, L.B.; Schepkin, M.G.
1981-01-01
Sum rules for neutrino oscillations are obtained. The derivation of the general form of the s matrix for two stage process lsub(i)sup(-)→ν→lsub(k)sup(+-) (where lsub(i)sup(-)e, μ, tau, ... are initial leptons with flavor i and lsub(k)sup(+-) is final lepton) is presented. The consideration of two stage process lsub(i)sup(-)→ν→lsub(k)sup(+-) gives the possibility to take into account neutrino masses and to obtain the expressions for the oscillating cross sections. In the case of Dirac and left-handed Majorana neutrino is obtained the sum rule for the quantities 1/Vsub(K)σ(lsub(i)sup(-)→lsub(K)sup(+-)), (where Vsub(K) is a velocity of lsub(K)). In the left-handed Majorana neutrino case there is an additional antineutrino admixture leading to lsub(i)sup(-)→lsub(K)sup(+) process. Both components (neutrino and antineutrino) oscillate independently. The sums Σsub(K)1/Vsub(k)σ(lsub(i)sup(-) - lsub(K)sup(+-) then oscillate due to the presence of left-handed antineutrinos and right-handed neutrinos which do not take part in weak interactions. If right-handed currents are added sum rules analogous to considered above may be obtained. All conclusions are valid in the general case when CP is not conserved [ru
International Nuclear Information System (INIS)
Dasgupta, Basudeb; Dighe, Amol; Mirizzi, Alessandro
2008-01-01
Collective neutrino flavor transformations deep inside a supernova are sensitive to the neutrino mass hierarchy even at extremely small values of θ 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 θ 13 -5 , where long baseline neutrino experiments would be ineffectual
Search for new candidates for the neutrino-oriented mass determination by electron-capture
Herfurth, F; Boehm, C; Blaum, K; Beck, D
2008-01-01
This proposal is part of an extended program dedicated to the neutrino-mass determination in the electron-capture sector, which aims at ultra-precise mass measurements by Penning traps in combination with cryogenic micro-calorimetry for atomic de-excitation measurements. Here, precise mass measurements with ISOLTRAP are proposed for the orbital electron-capture nuclides $^{194}$Hg and $^{202}$Pb, as well as their daughters, with the goal to determine accurately their Q-values. These values are expected to be the smallest ones among a great variety of known electron-capture precursors. Therefore, these nuclides are strong candidates for an improved electron-neutrino mass determination. We ask for 8 shifts of on-line beam at ISOLDE for mass measurements of $^{194}$Hg, $^{194}$ Au, $^{202}$Pb, and $^{202}$Tl at ISOLTRAP.
Large νμ-ντ mixing and the structure of right-handed Majorana mass matrix
International Nuclear Information System (INIS)
Matsuda, Masahisa
1993-01-01
Recent solar neutrino and atmospheric neutrino experiment suggest the existence of the large lepton mixing among 2nd and 3rd generation neutrino. This fact gives the important information on the structure of right-handed Majorana neutrino. It is shown that, if we assume that the neutrino Dirac mass matrix is similar to the mass matrix of the up-quark sector, the large lepton mixing among the 2nd and the 3rd generation requires the hierarchical structure of the Majorana mass matrix. This model-independent analyses serve the model-building of the mass matrices based on the quark-lepton unified theory. (author)
Light, rest mass and electric charge quanta all formed by neutrinos?
Chen, Shao-Guang
In high energy physics experiments the electric charge and rest mass of particles can commonly transform into the photons, vice versa. Its reason QFT can only give a vague answer: based on the particle creation and annihilation operators. There are not more clear answers or conjecture? At least, light, electric charge and rest mass should have a collective structure component, if not, the transformation is unable understanding. An elementary answer is that neutrino and antineutrino as their collective structure component. In the paper ‘Chen Qiliang & Wang Bin, The formation and characteristics of Chen Shaoguang's formula, China Science &Technology Overview 127101-103 (2011)’, the lowest energy state vertical polarized left spin 1/2 neutrino and right spin 1/2 antineutrino are just the left, right advance unit quanta la _{0}nuυ, ra nuυ _{0} and left, right back unit quanta lb (0) nuυ, rb nuυ (0) , it again compose into spin 1 unit photon la-ra _{0}nuυnuυ _{0} and back-photon lb-rb (0) nuυnuυ (0) , spin 0 unit rest mass ra-rb nuυ _{0}nuυ (0) and anti-mass la-lb _{0}nuυ (0) nuυ, spin 0 unit positive charge la-rb _{0}nuυnuυ (0) and negative charge ra-lb nuυ _{0} (0) nuυ. The physical vacuum is the even collocation of non-combinational nuυ _{0} or _{0}nuυ. It accord to the high energy physics experimental results of the transformation among the photons, masses quanta and charges quanta. In my paper ‘Quanta turn-advance ism, China Science && Technology Overview 131 192-210 (2011)’, QFT four-dimensional uncertainty principle and momentum-energy conservation law had been generalized as a five-dimensional equations: de Broglie wavelength as a position vector \\underline{q}= (i c t, r, s), momentum \\underline{P} = (i E / c, P, U c), \\underline{q} = i h / \\underline{P}, \\underline{q} \\underline{q} = 0, \\underline{P} \\underline{P} = 0, Sigma∑ \\underline{P} = \\underline{P} (0) . The five-dimensional time-space-spin had been quantized as a
Host, Ole; Lahav, Ofer; Abdalla, Filipe B.; Eitel, Klaus
2007-12-01
We present a showcase for deriving bounds on the neutrino masses from laboratory experiments and cosmological observations. We compare the frequentist and Bayesian bounds on the effective electron neutrino mass mβ which the KATRIN neutrino mass experiment is expected to obtain, using both an analytical likelihood function and Monte Carlo simulations of KATRIN. Assuming a uniform prior in mβ, we find that a null result yields an upper bound of about 0.17 eV at 90% confidence in the Bayesian analysis, to be compared with the frequentist KATRIN reference value of 0.20 eV. This is a significant difference when judged relative to the systematic and statistical uncertainties of the experiment. On the other hand, an input mβ=0.35eV, which is the KATRIN 5σ detection threshold, would be detected at virtually the same level. Finally, we combine the simulated KATRIN results with cosmological data in the form of present (post-WMAP) and future (simulated Planck) observations. If an input of mβ=0.2eV is assumed in our simulations, KATRIN alone excludes a zero neutrino mass at 2.2σ. Adding Planck data increases the probability of detection to a median 2.7σ. The analysis highlights the importance of combining cosmological and laboratory data on an equal footing.
International Nuclear Information System (INIS)
Host, Ole; Lahav, Ofer; Abdalla, Filipe B.; Eitel, Klaus
2007-01-01
We present a showcase for deriving bounds on the neutrino masses from laboratory experiments and cosmological observations. We compare the frequentist and Bayesian bounds on the effective electron neutrino mass m β which the KATRIN neutrino mass experiment is expected to obtain, using both an analytical likelihood function and Monte Carlo simulations of KATRIN. Assuming a uniform prior in m β , we find that a null result yields an upper bound of about 0.17 eV at 90% confidence in the Bayesian analysis, to be compared with the frequentist KATRIN reference value of 0.20 eV. This is a significant difference when judged relative to the systematic and statistical uncertainties of the experiment. On the other hand, an input m β =0.35 eV, which is the KATRIN 5σ detection threshold, would be detected at virtually the same level. Finally, we combine the simulated KATRIN results with cosmological data in the form of present (post-WMAP) and future (simulated Planck) observations. If an input of m β =0.2 eV is assumed in our simulations, KATRIN alone excludes a zero neutrino mass at 2.2σ. Adding Planck data increases the probability of detection to a median 2.7σ. The analysis highlights the importance of combining cosmological and laboratory data on an equal footing
Discriminating neutrino mass models using Type-II see-saw formula
Indian Academy of Sciences (India)
though a fuller analysis needs the full matrix form when all terms are present. This is followed by the normal hierarchical model (Type [III]) and inverted hierarchical model with opposite CP phase (Type [IIB]). γ ≃ 10−2 for both of them. Our main results on neutrino masses and mixings in Type-II see-saw formula are presented ...
DESI and other Dark Energy experiments in the era of neutrino mass measurements
Energy Technology Data Exchange (ETDEWEB)
Font-Ribera, Andreu [Institute of Theoretical Physics, University of Zurich, Winterthurerstrasse 190, Zurich, 8057 (Switzerland); McDonald, Patrick; Mostek, Nick; Reid, Beth A.; Seo, Hee-Jong [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720 (United States); Slosar, Anže, E-mail: afont@lbl.gov, E-mail: PVMcDonald@lbl.gov, E-mail: njmostek@lbl.gov, E-mail: BAReid@lbl.gov, E-mail: hee-jongseo@lbl.gov, E-mail: anze@bnl.gov [Brookhaven National Laboratory, Upton, NY, 11973 (United States)
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.
The revival of two old ways to measure the electron-neutrino mass
CERN. Geneva
2013-01-01
Meanwhile, the Tritium-decay neutrino-mass limits have improved by a factor of 15, and the difficulty of the experiments by the cube of that figure. Can the "calorimetric" EC theory cope with this increased challenge? I shall answer this question affirmatively. I shall also broach the ongoing beta-decay and EC experiments and report on progress i...
Status report on the Livermore-Rockefeller-Fermilab neutrino mass experiment
International Nuclear Information System (INIS)
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
KATRIN :a New Beta-Spectroscopic Experiment to Determine the Neutrino Mass
Czech Academy of Sciences Publication Activity Database
Dragoun, Otokar
2007-01-01
Roč. 958, - (2007), s. 193-196. ISBN 978-0-7354-0472-4. ISSN N R&D Projects: GA MŠk LC07050 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutrino mass * beta ray spectroscopy Subject RIV: BE - Theoretical Physics
Final results phase II of the Mainz neutrino mass search in tritium ß decay
Czech Academy of Sciences Publication Activity Database
Kraus, Ch.; Bornschein, B.; Bornschein, L.; Bonn, J.; Flatt, B.; Kovalík, Alojz; Ostrick, B.; Otten, E.W.; Schall, J.P.; Thümmler, Th.; Weinheimer, Ch.
2005-01-01
Roč. 40, - (2005), s. 447-468 ISSN 1434-6001 R&D Projects: GA MŠk 1P04LA213 Institutional research plan: CEZ:AV0Z10480505 Keywords : neutrino mass * tritium beta decay Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.659, year: 2005
International Nuclear Information System (INIS)
Pascoli, S.; Petcov, S.T.
2004-01-01
We update our earlier study [Phys. Lett. B 544 (2002) 239], which was inspired by the 2002 SNO data, on the implications of the results of the solar neutrino experiments for the predictions of the effective Majorana mass in neutrinoless double beta-decay, vertical bar vertical bar. We obtain predictions for vertical bar vertical bar using the values of the neutrino oscillation parameters, obtained in the analyzes of the presently available solar neutrino data, including the just published data from the salt phase of the SNO experiment, the atmospheric neutrino and CHOOZ data and the first data from the KamLAND experiment. The main conclusion reached in the previous study [Phys. Lett. B 544 (2002) 239] of the existence of significant lower bounds on vertical bar vertical bar in the cases of neutrino mass spectrum of inverted hierarchical (IH) and quasi-degenerate (QD) type is strongly reinforced by fact that combined solar neutrino data (i) exclude the possibility of cos2θ o =0 at more than 5 s.d., (ii) determine as a best fit value cos2θ o =0.40, and (iii) imply at 95% C.L. that cos2θ o ∼>0.22, θ o being the solar neutrino mixing angle. For the IH and QD spectra we get using, e.g., the 90% C.L. allowed ranges of values of the oscillation parameters, vertical bar vertical bar ∼>0.010 eV and vertical bar vertical bar ∼>0.043 eV, respectively. We also comment on the possibility to get information on the neutrino mass spectrum and on the CP-violation in the lepton sector due to Majorana CP-violating phases
The effective neutrino charge radius in the presence of fermion masses
International Nuclear Information System (INIS)
Binosi, D.; Bernabeu, J.; Papavassiliou, J.
2005-01-01
We show how the crucial gauge cancellations leading to a physical definition of an effective neutrino charge radius persist in the presence of non-vanishing fermion masses. An explicit one-loop calculation demonstrates that, as happens in the massless case, the pinch technique rearrangement of the Feynman amplitudes, together with the judicious exploitation of the fundamental current relation J α (3) =2(J Z +sinθ w 2 J γ ) α , leads to a completely gauge independent definition of the effective neutrino charge radius. Using the formalism of the Nielsen identities it is further proved that the same cancellation mechanism operates unaltered to all orders in perturbation theory
Díaz, M.; Hirsch, M.; Porod, W.; Romão, J.; Valle, J.
2003-07-01
We give an analytical calculation of solar neutrino masses and mixing at one-loop order within bilinear R-parity breaking supersymmetry, and compare our results to the exact numerical calculation. Our method is based on a systematic perturbative expansion of R-parity violating vertices to leading order. We find in general quite good agreement between the approximate and full numerical calculations, but the approximate expressions are much simpler to implement. Our formalism works especially well for the case of the large mixing angle Mikheyev-Smirnov-Wolfenstein solution, now strongly favored by the recent KamLAND reactor neutrino data.
The nucleon axial mass and the MiniBooNE quasielastic neutrino-nucleus scattering problem
International Nuclear Information System (INIS)
Nieves, J.; Ruiz Simo, I.; Vicente Vacas, M.J.
2012-01-01
The charged-current double differential neutrino cross section, measured by the MiniBooNE Collaboration, has been analyzed using a microscopical model that accounts for, among other nuclear effects, long range nuclear (RPA) correlations and multinucleon scattering. We find that MiniBooNE data are fully compatible with the world average of the nucleon axial mass in contrast with several previous analyses which have suggested an anomalously large value. We also discuss the reliability of the algorithm used to estimate the neutrino energy.
Phenomenological study of extended seesaw model for light sterile neutrino
International Nuclear Information System (INIS)
Nath, Newton; Ghosh, Monojit; Goswami, Srubabati; Gupta, Shivani
2017-01-01
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 .
The Neutrino mass matrix after Kamland and SNO salt enhanced results
Aliani, P; Picariello, M; Torrente-Lujan, E
2003-01-01
An updated analysis of all available neutrino oscillation evidence in Solar experiments including the latest SNO ES,CC and NC data (254d live time, NaCL enhanced efficiency) is presented. We obtain, for the fraction of active oscillating neutrinos: sin^2alpha=(\\Phi_{NC}-\\Phi_{CC})/(\\Phi_{SSM}-\\Phi_{CC})=0.94^{+0.0.065}_{-0.060 } nearly 20\\sigma from the pure sterile oscillation case. The fraction of oscillating sterile neutrinos cos^2\\alpha \\lsim 0.12 (1 sigma CL). At face value, these results might slightly favour the existence of a small sterile oscillating sector. In the framework of two active neutrino oscillations we determine individual neutrino mixing parameters and their errors we obtain Delta m^2= 7.01\\pm 0.08 \\times 10^{-5} eV^2, tan^2 theta=0.42^{+0.12}_{-0.07}. The main difference with previous analysis is a better resolution in parameter space. In particular the secondary region at larger mass differences (LMAII) is now excluded at 95% CL. The combined analysis of solar and Kamland data concludes...
International Nuclear Information System (INIS)
Nasri, Salah; Schechter, Joseph; Moussa, Sherif
2004-01-01
We further study the previously proposed ansatz, Tr(M ν )=0, for a prediagonal light Majorana type neutrino mass matrix. If CP violation is neglected this enables one to use the existing data on squared mass differences to estimate (up to a discrete ambiguity) the neutrino masses themselves. If it is assumed that only the conventional CP phase is present, the ansatz enables us to estimate this phase in addition to all three masses. If it is assumed that only the two Majorana CP phases are present, the ansatz enables us to present a one parameter family of solutions for the masses and phases. This enables us to obtain a simple 'global' view of lepton number violation effects. Furthermore using an SO(10) motivation for the ansatz suggests an amusing toy (clone) model in which the heavy neutrinos have the same mixing pattern and mass ratios as the light ones. In this case only their overall mass scale is not known (although it is constrained by the initial motivation). Using this toy model we make a rough estimate of the magnitude of the baryon to photon ratio induced by the leptogenesis mechanism. Solutions close to the CP conserving cases seem to be favored
Neutrino masses via the Zee mechanism in the 5D split fermion model
International Nuclear Information System (INIS)
Chang, We-Fu; Chen, I-Ting; Liou, Siao-Cing
2011-01-01
We study the original version of the Zee model, where both of the SU(2) L Higgs doublets are allowed to couple to the leptons, in the framework of the split fermion model in M 4 xS 1 /Z 2 space-time. The neutrino masses are generated through 1-loop diagrams without introducing the right-handed neutrinos. By assuming an order one anarchical complex 5D Yukawa couplings, all the effective 4D Yukawa couplings are determined by the wave function overlap between the split fermions and the bulk scalars in the fifth dimension. The predictability of the Yukawa couplings is in sharp contrast to the original Zee model in 4D where the Yukawa couplings are unknown free parameters. This setup exhibits a geometrical alternative to the lepton flavor symmetry. By giving four explicit sets of the split fermion locations, we demonstrate that it is possible to simultaneously fit the lepton masses and neutrino oscillation data by just a handful free parameters without much fine tuning. Moreover, we are able to make definite predictions for the mixing angle θ 13 , the absolute neutrino masses, and the lepton flavor violation processes for each configuration.
Physical effects involved in the measurements of neutrino masses with future cosmological data
Energy Technology Data Exchange (ETDEWEB)
Archidiacono, Maria; Brinckmann, Thejs; Lesgourgues, Julien; Poulin, Vivian, E-mail: archidiacono@physik.rwth-aachen.de, E-mail: brinckmann@physik.rwth-aachen.de, E-mail: lesgourg@physik.rwth-aachen.de, E-mail: poulin@lapth.cnrs.fr [Institute for Theoretical Particle Physics and Cosmology (TTK), RWTH Aachen University, D-52056 Aachen (Germany)
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 M {sub ν} and the optical depth at reionization τ{sub reio}, 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 M {sub ν}. For instance, an independent determination of the optical depth with an accuracy of σ(τ{sub reio})=0.001 (which might be achievable, although this is subject to astrophysical uncertainties) would decrease the uncertainty down to σ( M {sub ν})=12 meV.
Discrete Symmetries and Neutrino Mass Perturbations for θ$_{13}$
Hall, L J
2013-01-01
The recent measurement of the third lepton mixing angle, \\theta_{13}, has shown that, although small compared to \\theta_{12} and \\theta_{23}, it is much larger than anticipated in schemes that generate Tri-Bi-Maximal (TBM) or Golden Ratio (GR) mixing. We develop a model-independent formalism for perturbations away from exact TBM or GR mixing in the neutrino sector. Each resulting perturbation scheme reflects an underlying symmetry structure and involves a single complex parameter. We show that such perturbations can readily fit the observed value of \\theta_{13}, which is then correlated with a change in the other mixing angles. We also determine the implication for the lepton CP violating phases. For comparison we determine the predictions for Bi-Maximal mixing corrected by charged lepton mixing and we discuss the accuracy that will be needed to distinguish between the various schemes.
Calorimetric measurements of $^{163}$ holmium decay as tools to determine the electron neutrino mass
De Rújula, Alvaro
1982-01-01
Computes the spectrum of 'calorimetric' energy in the electron capture decay of /sup 163/Ho. A calorimetric experiment would yield an excellent determination of (/sup 163/Ho, /sup 163/Dy) mass difference. The proximity of the spectral endpoint to an atomic resonance makes the fraction of events that are sensitive to a non-zero neutrino mass superior in /sup 163/Ho decay than in tritium decay.
Neutrino masses, leptogenesis and dark matter from small lepton number violation?
Energy Technology Data Exchange (ETDEWEB)
Abada, Asmaa [CNRS, Univ. Paris-Sud, Univ. Paris-Saclay, Orsay (France). Lab. de Physique Theorique; Arcadi, Giorgio [Max Planck Institut fuer Kernphysik, Heidelberg (Germany); Domcke, Valerie [Paris Diderot Univ. (France). AstroParticule et Cosmologie (APC)/Paris Centre for Cosmological Physics (PCCP); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Lucente, Michele [Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium). Centre for Cosmology, Particle Physics and Phenomenology (CP3)
2017-09-05
We consider the possibility of simultaneously addressing the baryon asymmetry of the Universe, the dark matter problem and the neutrino mass generation in minimal extensions of the Standard Model via sterile fermions with (small) total lepton number violation. Within the framework of Inverse and Linear Seesaw models, the small lepton number violating parameters set the mass scale of the active neutrinos, the efficiency of leptogenesis through a small mass splitting between pairs of sterile fermions as well as the mass scale of a sterile neutrino dark matter candidate. We provide an improved parametrization of these seesaw models taking into account existing experimental constraints and derive a linearized system of Boltzmann equations to describe the leptogenesis process, which allows for an efficient investigation of the parameter space. This in particular enables us to perform a systematic study of the strong washout regime of leptogenesis. Our study reveals that one can have a successful leptogenesis at the temperature of the electroweak scale through oscillations between two sterile states with a natural origin of the (necessary) strong degeneracy in their mass spectrum. The minimal model however requires a non-standard cosmological history to account for the relic dark matter. Finally, we discuss the prospect for neutrinoless double beta decay and for testing, in future experiments, the values of mass and different active-sterile mixings required for successful leptogenesis.
Neutrino masses, leptogenesis and dark matter from small lepton number violation?
International Nuclear Information System (INIS)
Abada, Asmaa; Domcke, Valerie; Lucente, Michele
2017-01-01
We consider the possibility of simultaneously addressing the baryon asymmetry of the Universe, the dark matter problem and the neutrino mass generation in minimal extensions of the Standard Model via sterile fermions with (small) total lepton number violation. Within the framework of Inverse and Linear Seesaw models, the small lepton number violating parameters set the mass scale of the active neutrinos, the efficiency of leptogenesis through a small mass splitting between pairs of sterile fermions as well as the mass scale of a sterile neutrino dark matter candidate. We provide an improved parametrization of these seesaw models taking into account existing experimental constraints and derive a linearized system of Boltzmann equations to describe the leptogenesis process, which allows for an efficient investigation of the parameter space. This in particular enables us to perform a systematic study of the strong washout regime of leptogenesis. Our study reveals that one can have a successful leptogenesis at the temperature of the electroweak scale through oscillations between two sterile states with a natural origin of the (necessary) strong degeneracy in their mass spectrum. The minimal model however requires a non-standard cosmological history to account for the relic dark matter. Finally, we discuss the prospect for neutrinoless double beta decay and for testing, in future experiments, the values of mass and different active-sterile mixings required for successful leptogenesis.
Neutrino masses, leptogenesis and dark matter from small lepton number violation?
Abada, Asmaa; Arcadi, Giorgio; Domcke, Valerie; Lucente, Michele
2017-12-01
We consider the possibility of simultaneously addressing the baryon asymmetry of the Universe, the dark matter problem and the neutrino mass generation in minimal extensions of the Standard Model via sterile fermions with (small) total lepton number violation. Within the framework of Inverse and Linear Seesaw models, the small lepton number violating parameters set the mass scale of the active neutrinos, the efficiency of leptogenesis through a small mass splitting between pairs of sterile fermions as well as the mass scale of a sterile neutrino dark matter candidate. We provide an improved parametrization of these seesaw models taking into account existing experimental constraints and derive a linearized system of Boltzmann equations to describe the leptogenesis process, which allows for an efficient investigation of the parameter space. This in particular enables us to perform a systematic study of the strong washout regime of leptogenesis. Our study reveals that one can have a successful leptogenesis at the temperature of the electroweak scale through oscillations between two sterile states with a natural origin of the (necessary) strong degeneracy in their mass spectrum. The minimal model however requires a non-standard cosmological history to account for the relic dark matter. Finally, we discuss the prospect for neutrinoless double beta decay and for testing, in future experiments, the values of mass and different active-sterile mixings required for successful leptogenesis.
152nd International School of Physics "Enrico Fermi": Neutrino Physics
Declais, Y; Strolin, P; Zanotti, L; Società Italiana di Fisica. Bologna. Scuola internazionale di fisica "Enrico Fermi"; International School of Physics "Enrico Fermi": Neutrino Physics; Scuola Internazionale di Fisica "Enrico Fermi" : Phisica dei neutrini
2003-01-01
Neutrino physics contributed in an fundamental way to the progress of science, opening important windows of knowledge in elementary particle physics, as well in astrophysics and cosmology. Substantial experimental efforts are presently dedicated to improve our knowledge on neutrino properties as, in fact, we don't know yet some of the basic ones. Although very significant steps forward have been done, neutrino masses and mixings still remain largely unknown and constitute an important field for future research. Are neutrinos Majorana or Dirac particles? Have they a magnetic moment? Historically, studies on weak processes and, therefore, on neutrino physics, provided first the Fermi theory of weak interactions and then the V-A theory. Finally, the observation of weak neutral currents provided the first experimental evidence for unification of weak and electromagnetic interactions by the so called "Standard Model' of elementary particles. In addition to the results obtained from the measurement of the solar neu...
Supersymmetric Dirac-Born-Infeld action with self-dual mass term
International Nuclear Information System (INIS)
Nishino, Hitoshi; Rajpoot, Subhash; Reed, Kevin
2005-01-01
We introduce a Dirac-Born-Infeld action to a self-dual N = 1 supersymmetric vector multiplet in three dimensions. This action is based on the supersymmetric generalized self-duality in odd dimensions developed originally by Townsend, Pilch and van Nieuwenhuizen. Even though such a self-duality had been supposed to be very difficult to generalize to a supersymmetrically interacting system, we show that the Dirac-Born-Infeld action is actually compatible with supersymmetry and self-duality in three dimensions, even though the original self-duality receives corrections by the Dirac-Born-Infeld action. The interactions can be further generalized to arbitrary (non)polynomial interactions. As a by-product, we also show that a third-rank field strength leads to a more natural formulation of self-duality in 3D. We also show an interesting role played by the third-rank field strength leading to supersymmetry breaking, in addition to accommodating a Chern-Simons form
Wehling, T. O.; Black-Schaffer, A. M.; Balatsky, A. V.
2014-01-01
A wide range of materials, like d-wave superconductors, graphene, and topological insulators, share a fundamental similarity: their low-energy fermionic excitations behave as massless Dirac particles rather than fermions obeying the usual Schrodinger Hamiltonian. This emergent behavior of Dirac fermions in condensed matter systems defines the unifying framework for a class of materials we call "Dirac materials''. In order to establish this class of materials, we illustrate how Dirac fermions ...
International Nuclear Information System (INIS)
Anon.
2007-01-01
Paper deals with the information on the occurrence of the fields of the sterile neutrinos (the righthanded ones) mixed with the normal neutrinos (the lefthanded ones). Both the Max Plank Radioastronomy Institute and the Los Angeles University assumes that the occurrence of the keV mass sterile neutrinos may explain the dark matter nature, the fast rotation of the observed pulsars and the reionization processes. The issues associated with the possibility to record the sterile neutrinos were analyzed in the course of the Sterile Neutrinos in Astrophysics and Cosmology Workshop (Crans Montana, March 2006 [ru
Neutrino masses and a low breaking scale of left-right symmetry
International Nuclear Information System (INIS)
Khasanov, Oleg; Perez, Gilad
2002-01-01
In left-right symmetric models (LRSMs) the light neutrino masses arise from two sources: the seesaw mechanism and a vacuum expectation value of an SU(2) L triplet. If the left-right symmetry breaking v R is low, v R (less-or-similar sign)15 TeV, the contributions to the light neutrino masses from both the seesaw mechanism and the triplet Yukawa couplings are expected to be well above the experimental bounds. We present a minimal LRSM with an additional U(1) symmetry in which the masses induced by the two sources are below the eV scale and the twofold problem is solved. We further show that, if the U(1) symmetry is also responsible for the lepton flavor structure, the model yields a small mixing angle within the first two lepton generations
Final scientific and technical report: New experiments to measure the neutrino mass scale
Energy Technology Data Exchange (ETDEWEB)
Monreal, Benjamin [Univ. of California, Santa Barbara, CA (United States)
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.
Mass hierarchy sensitivity of medium baseline reactor neutrino experiments with multiple detectors
Directory of Open Access Journals (Sweden)
Hong-Xin Wang
2017-05-01
Full Text Available We report the neutrino mass hierarchy (MH determination of medium baseline reactor neutrino experiments with multiple detectors, where the sensitivity of measuring the MH can be significantly improved by adding a near detector. Then the impact of the baseline and target mass of the near detector on the combined MH sensitivity has been studied thoroughly. The optimal selections of the baseline and target mass of the near detector are ∼12.5 km and ∼4 kton respectively for a far detector with the target mass of 20 kton and the baseline of 52.5 km. As typical examples of future medium baseline reactor neutrino experiments, the optimal location and target mass of the near detector are selected for the specific configurations of JUNO and RENO-50. Finally, we discuss distinct effects of the reactor antineutrino energy spectrum uncertainty for setups of a single detector and double detectors, which indicate that the spectrum uncertainty can be well constrained in the presence of the near detector.
Mass hierarchy sensitivity of medium baseline reactor neutrino experiments with multiple detectors
Energy Technology Data Exchange (ETDEWEB)
Wang, Hong-Xin, E-mail: hxwang@iphy.me [Department of Physics, Nanjing University, Nanjing 210093 (China); Zhan, Liang; Li, Yu-Feng; Cao, Guo-Fu [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Chen, Shen-Jian [Department of Physics, Nanjing University, Nanjing 210093 (China)
2017-05-15
We report the neutrino mass hierarchy (MH) determination of medium baseline reactor neutrino experiments with multiple detectors, where the sensitivity of measuring the MH can be significantly improved by adding a near detector. Then the impact of the baseline and target mass of the near detector on the combined MH sensitivity has been studied thoroughly. The optimal selections of the baseline and target mass of the near detector are ∼12.5 km and ∼4 kton respectively for a far detector with the target mass of 20 kton and the baseline of 52.5 km. As typical examples of future medium baseline reactor neutrino experiments, the optimal location and target mass of the near detector are selected for the specific configurations of JUNO and RENO-50. Finally, we discuss distinct effects of the reactor antineutrino energy spectrum uncertainty for setups of a single detector and double detectors, which indicate that the spectrum uncertainty can be well constrained in the presence of the near detector.
Neutrino mixing and future accelerator neutrino experiments
International Nuclear Information System (INIS)
Bilenky, S.M.
1992-01-01
No evidence for neutrino mixing has been obtained in experiments searching for oscillations with neutrinos from accelerators and reactors. The possible reason is that neutrino masses are too small to produce any sizable effects in the experiments with terrestrial neutrinos. We put forward here the point of view that the reason for that can be traced to the presence of a hierarchy of neutrino masses as well as strength of couplings between lepton families. (orig.)
Proceedings of the 9th workshop on the mass of the electron neutrino
International Nuclear Information System (INIS)
Yasumi, Shinjiro
1984-03-01
The 9th workshop on the mass of electron neutrinos was held at KEK, Japan. The experimental studies concerning the M-shell of Dy atoms for the measurement of the mass of electron neutrinos were presented at the workshop. The reports included in this proceedings concern windowless Si(Li) detectors, the irradiation technique to make Ho-163 radioactive sources, high purity Ho-163 sources, the M X-ray spectra of rare earth atoms, the study on the M-shell of Dy atoms by using monochromatic X-ray from the KEK PF (Photon Factory), the absolute measurement of photon beam flux, the angular distribution of M X-ray accompanying the photoelectric effect caused by linearly polarized photons, the X-ray spectrum around the 5p to 3s peak accompanying the decay of Ho-163, and the data of nuclear matrix elements of the electron capture decay of Ho-163. The reports presented at the previous workshop are also included in this proceedings. They concern the theoretical calculation of the M X-ray spectrum of Dy, the mass measurement of electron neutrinos, the X-ray spectrum of Ho-163 sources, the amount of Dy-164 contained in Ho-163 samples, and the isotope dilution mass spectrometry. (Kato, T.)
Lepton flavor violation and scalar dark matter in a radiative model of neutrino masses
Energy Technology Data Exchange (ETDEWEB)
Esch, Sonja; Klasen, Michael; Lamprea, David R. [Westfaelische Wilhelms-Universitaet Muenster, Institut fuer Theoretische Physik, Muenster (Germany); Yaguna, Carlos E. [Universidad Pedagogica y Tecnologica de Colombia, Escuela de Fisica, Tunja (Colombia)
2018-02-15
We consider a simple extension of the Standard Model that can account for the dark matter and explain the existence of neutrino masses. The model includes a vector-like doublet of SU(2), a singlet fermion, and two scalar singlets, all of them odd under a new Z{sub 2} symmetry. Neutrino masses are generated radiatively by one-loop processes involving the new fields, while the dark matter candidate is the lightest neutral particle among them. We focus specifically on the case where the dark matter particle is one of the scalars and its relic density is determined by its Yukawa interactions. The phenomenology of this setup, including neutrino masses, dark matter and lepton flavor violation, is analyzed in some detail. We find that the dark matter mass must be below 600 GeV to satisfy the relic density constraint. Lepton flavor violating processes are shown to provide the most promising way to test this scenario. Future μ → 3e and μ-e conversion experiments, in particular, have the potential to probe the entire viable parameter space of this model. (orig.)
A possible solution of the flavor problem and radiative neutrino masses
International Nuclear Information System (INIS)
Adulpravitchai, Adisorn
2010-01-01
In this thesis, we discuss two important problems of the Standard Model of Particle Physics (SM), namely the flavor problem and the reason for the smallness of neutrino masses. The first one might be related to the origin of non-abelian discrete flavor symmetries. We discuss the possibility of obtaining them from an underlying continuous flavor symmetry, i.e. SU(2) or SU(3) through spontaneous symmetry breaking. Moreover, we investigate their possible origin from an orbifold compactification. We discuss all non-abelian discrete symmetries, which can arise from an orbifold T 2 /Z N . They are A 4 , S 4 , D 4 , D 3 , and D 6 . We present the idea of combining the breaking of an orbifold GUT and the flavor symmetry arising from the orbifold. We demonstrate the construction in a 6d SUSY SO(10) x S 4 . For the second problem, we propose a one-loop neutrino mass model in the left-right symmetric framework. We observe the transmitted hierarchy from the charged lepton masses to the right-handed neutrino masses, which we call ''Radiative Transmission of Lepton Flavor Hierarchy''. Finally, we study the phenomenological aspects of the model such as lepton flavor violation (LFV), flavor number violation (FNV), and flavor changing neutral currents (FCNCs). (orig.)
Constraints on lifetime and mass of heavy lepton neutrinos imposed by big bang nucleosynthesis
International Nuclear Information System (INIS)
Miyama, Shoken; Sato, Katsuhiko
1978-01-01
If there exist massive neutral leptons (heavy neutrinos), they would have been produced in thermal equilibrium in the early stages of the universe. The effects of their presence and decay on the big bang nucleosynthesis are investigated in detail and abundances of the products 4 He, 2 H and 7 Li are compared with the observed cosmic abundances. We have determined a region in the lifetime-mass diagram of the heavy neutrino which should be ruled out in order for the big bang nucleosynthesis not to conflict with observed abundances of the elements. In addition, if a lower limit of the lifetime obtained from the Weinberg-Salam type theory, tau>=6 x 10 7 (1 MeV/m sub(νh)) 5 sec, is assumed, where m sub(νh) is the mass of the heavy neutrino, the mass range of 70 eV< m sub(νh)<10 MeV is ruled out. The other constraints on the mass and the lifetime obtained from astrophysical considerations are also discussed and summarized. (author)
A possible solution of the flavor problem and radiative neutrino masses
Energy Technology Data Exchange (ETDEWEB)
Adulpravitchai, Adisorn
2010-06-23
In this thesis, we discuss two important problems of the Standard Model of Particle Physics (SM), namely the flavor problem and the reason for the smallness of neutrino masses. The first one might be related to the origin of non-abelian discrete flavor symmetries. We discuss the possibility of obtaining them from an underlying continuous flavor symmetry, i.e. SU(2) or SU(3) through spontaneous symmetry breaking. Moreover, we investigate their possible origin from an orbifold compactification. We discuss all non-abelian discrete symmetries, which can arise from an orbifold T{sup 2}/Z{sub N}. They are A{sub 4}, S{sub 4}, D{sub 4}, D{sub 3}, and D{sub 6}. We present the idea of combining the breaking of an orbifold GUT and the flavor symmetry arising from the orbifold. We demonstrate the construction in a 6d SUSY SO(10) x S{sub 4}. For the second problem, we propose a one-loop neutrino mass model in the left-right symmetric framework. We observe the transmitted hierarchy from the charged lepton masses to the right-handed neutrino masses, which we call ''Radiative Transmission of Lepton Flavor Hierarchy''. Finally, we study the phenomenological aspects of the model such as lepton flavor violation (LFV), flavor number violation (FNV), and flavor changing neutral currents (FCNCs). (orig.)
A search for neutrino–antineutrino mass inequality by means of sterile neutrino oscillometry
Energy Technology Data Exchange (ETDEWEB)
Smirnov, M.V., E-mail: gear8mike@gmail.com [Department of Physics, University of Jyväskylä, 40014 Jyväskylä (Finland); St. Petersburg State University, 198504 Peterhof, St. Petersburg (Russian Federation); Loo, K.K. [Department of Physics, University of Jyväskylä, 40014 Jyväskylä (Finland); Novikov, Yu.N. [St. Petersburg State University, 198504 Peterhof, St. Petersburg (Russian Federation); Petersburg Nuclear Physics Institute, 188300 Gatchina, St. Petersburg (Russian Federation); Trzaska, W.H. [Department of Physics, University of Jyväskylä, 40014 Jyväskylä (Finland); Wurm, M. [Johannes Gutenberg University Mainz, 55099 Mainz (Germany)
2015-11-15
The investigation of the oscillation pattern induced by the sterile neutrinos might determine the oscillation parameters, and at the same time, allow to probe CPT symmetry in the leptonic sector through neutrino–antineutrino mass inequality. We propose to use a large scintillation detector like JUNO or LENA to detect electron neutrinos and electron antineutrinos from MCi electron capture or beta decay sources. Our calculations indicate that such an experiment is realistic and could be performed in parallel to the current research plans for JUNO and RENO. Requiring at least 5σ confidence level and assuming the values of the oscillation parameters indicated by the current global fit, we would be able to detect neutrino–antineutrino mass inequality of the order of 0.5% or larger, which would imply a signal of CPT anomalies.
Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen
Gando, A.; Gando, Y.; Hachiya, T.; Hayashi, A.; Hayashida, S.; Ikeda, H.; Inoue, K.; Ishidoshiro, K.; Karino, Y.; Koga, M.; Matsuda, S.; Mitsui, T.; Nakamura, K.; Obara, S.; Oura, T.; Ozaki, H.; Shimizu, I.; Shirahata, Y.; Shirai, J.; Suzuki, A.; Takai, T.; Tamae, K.; Teraoka, Y.; Ueshima, K.; Watanabe, H.; Kozlov, A.; Takemoto, Y.; Yoshida, S.; Fushimi, K.; Banks, T. I.; Berger, B. E.; Fujikawa, B. K.; O'Donnell, T.; Winslow, L. A.; Efremenko, Y.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Detwiler, J. A.; Enomoto, S.; Decowski, M. P.; KamLAND-Zen Collaboration
2016-08-01
We present an improved search for neutrinoless double-beta (0 ν β β ) decay of 136Xe in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a significant reduction of the Agm110 contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0 ν β β decay half-life of T1/2 0 ν>1.07 ×1 026 yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.
Radiative neutrino mass and Majorana dark matter within an inert Higgs doublet model
Ahriche, Amine; Jueid, Adil; Nasri, Salah
2018-05-01
We consider an extension of the standard model (SM) with an inert Higgs doublet and three Majorana singlet fermions to address both origin and the smallness of neutrino masses and dark matter (DM) problems. In this setup, the lightest Majorana singlet fermion plays the role of DM candidate and the model parameter space can be accommodated to avoid different experimental constraints such as lepton flavor violating processes and electroweak precision tests. The neutrino mass is generated at one-loop level a la Scotogenic model and its smallness is ensured by the degeneracy between the C P -odd and C P -even scalar members of the inert doublet. Interesting signatures at both leptonic and hadronic colliders are discussed.
Charged lepton flavor violation in a class of radiative neutrino mass generation models
Chowdhury, Talal Ahmed; Nasri, Salah
2018-04-01
We investigate the charged lepton flavor violating processes μ →e γ , μ →e e e ¯, and μ -e conversion in nuclei for a class of three-loop radiative neutrino mass generation models with electroweak multiplets of increasing order. We find that, because of certain cancellations among various one-loop diagrams which give the dipole and nondipole contributions in an effective μ e γ vertex and a Z-penguin contribution in an effective μ e Z vertex, the flavor violating processes μ →e γ and μ -e conversion in nuclei become highly suppressed compared to μ →e e e ¯ process. Therefore, the observation of such a pattern in LFV processes may reveal the radiative mechanism behind neutrino mass generation.
International Nuclear Information System (INIS)
Bellini, G.; Caccianiga, B.; Giammarchi, M.G.
2001-01-01
The unique features of the CTF and BOREXINO set-ups are used for a high sensitivity study of 100 Mo and 116 Cd neutrinoless 2β decay. Pilot measurements with 116 Cd and Monte Carlo simulation show that the sensitivity of the CAMEO experiment (in terms of the T 1/2 limit for 0ν2β decay) is (3-5) · 10 24 y with a 1 kg source of 100 Mo ( 116 Cd, 82 Se, 150 Nd) and ∼ 10 26 y with 65 kg of 116 CdWO 4 crystals placed in the CTF. The last value corresponds to a limit on the neutrino mass of m ν ≤ 0.06 eV. Moreover, with 1000 kg of 116 CdWO 4 crystals located in the BOREXINO apparatus, the neutrino mass limit can be pushed down to m ν ≤ 0.02 eV
Dirac spectral density and mass anomalous dimension in 2+1 flavor QCD
Directory of Open Access Journals (Sweden)
Nakayama Katsumasa
2018-01-01
Full Text Available We compute the Dirac spectral density of QCD in a wide range of eigenvalues by using a stochastic method. We use 2+1 flavor lattice ensembles generated with Mobius domain-wall fermion at three lattice spacings (a = 0:083; 0:055; 0:044 fm to estimate the continuum limit. The discretization effect can be minimized by a generalization of the valence domain-wall fermion. The spectral density at relatively high eigenvalues can be matched with perturbation theory. We compare the lattice results with the perturbative expansion available to O(α4s.
Direct search for neutrino mass and anomaly in the tritium beta-spectrum
International Nuclear Information System (INIS)
Lobashev, V.M.; Assev, V.N.; Belesev, A.I.; Berlev, A.I.; Geraskin, E.V.; Golubev, A.A.; Kazachenko, O.V.; Kuznetsov, Y.E.; Ostroumov, R.P.; Rivkis, L.A.; Stern, B.E.; Titov, N.A.; Zasoroghny, C.V.; Zakharov, Y.I.
2001-01-01
Results of the ''Troitsk ν-mass'' experiment on search for the neutrino rest mass in the tritium beta-decay are presented. Study of time dependence of anomalous, bump-like structure at the end of the beta spectrum reported earlier gives indication of a periodic shift of the position of the bump with respect to the end-point energy with period of 0.5 year. New upper limit for electron antineutrino rest mass m ν 2 is derived after accounting for the bump. (authors)
Experimental Neutrino Physics: Final Report
Energy Technology Data Exchange (ETDEWEB)
Lane, Charles E.; Maricic, Jelena
2012-09-05
Experimental studies of neutrino properties, with particular emphasis on neutrino oscillation, mass and mixing parameters. This research was pursued by means of underground detectors for reactor anti-neutrinos, measuring the flux and energy spectra of the neutrinos. More recent investigations have been aimed and developing detector technologies for a long-baseline neutrino experiment (LBNE) using a neutrino beam from Fermilab.
Soft see-saw: Radiative origin of neutrino masses in SUSY theories
Directory of Open Access Journals (Sweden)
Luka Megrelidze
2017-01-01
Full Text Available Radiative neutrino mass generation within supersymmetric (SUSY construction is studied. The mechanism is considered where the lepton number violation is originating from the soft SUSY breaking terms. This requires MSSM extensions with states around the TeV scale. We present several explicit realizations based on extensions either by MSSM singlet or SU(2w triplet states. Besides some novelties of the proposed scenarios, various phenomenological implications are also discussed.
Symmetric neutrino mass matrix with two zeros in SUSY SO(10) GUT
International Nuclear Information System (INIS)
Bando, Masako; Kaneko, Satoru; Obara, Midori; Tanimoto, Morimitsu
2004-01-01
We study the symmetric 2-zero texture of lepton and quark mass matrix, for the SUSY SO(10) GUT model including the Pati-Salam symmetry. We show that our model can simultaneously explain the current neutrino experimental data, predicted rate of lepton flavor violating processes are safely below the experimental bounds and baryon asymmetry of the universe can be obtained through thermal leptogenesis. (author)
Starobinsky-like inflation and neutrino masses in a no-scale SO(10) model
Energy Technology Data Exchange (ETDEWEB)
Ellis, John [Theoretical Particle Physics and Cosmology Group,Department of Physics, King’s College London, WC2R 2LS London (United Kingdom); Theoretical Physics Department, CERN,CH-1211 Geneva 23 (Switzerland); Garcia, Marcos A.G. [Physics and Astronomy Department, Rice University,6100 Main Street, Houston, TX 77005 (United States); Nagata, Natsumi [Department of Physics, University of Tokyo,Bunkyo-ku, Tokyo 113-0033 (Japan); Nanopoulos, Dimitri V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy,Texas A& M University, College Station, 77843 Texas (United States); Olive, Keith A. [William I. Fine Theoretical Physics Institute, School of Physics and Astronomy, University of Minnesota,116 Church Street SE, Minneapolis, MN 55455 (United States)
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.
Giachero, A.; Day, P. K.; Falferi, P.; Faverzani, M.; Ferri, E.; Giordano, C.; Maino, M.; Margesin, B.; Mezzena, R.; Nizzolo, R.; Nucciotti, A.; Puiu, A.; Zanetti, L.
2015-01-01
The European Research Council has recently funded HOLMES, a project with the aim of performing a calorimetric measurement of the electron neutrino mass measuring the energy released in the electron capture decay of 163Ho. The baseline for HOLMES are microcalorimeters coupled to Transition Edge Sensors (TESs) read out with rf-SQUIDs, for microwave multiplexing purposes. A promising alternative solution is based on superconducting microwave resonators, that have undergone rapid development in t...
New scotogenic model of neutrino mass with U(1){sub D} gauge interaction
Energy Technology Data Exchange (ETDEWEB)
Ma, Ernest [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Picek, Ivica; Radovčić, Branimir [Department of Physics, Faculty of Science, University of Zagreb, P.O.B. 331, HR-10002 Zagreb (Croatia)
2013-11-04
We propose a new realization of the one-loop radiative model of neutrino mass generated by dark matter (scotogenic), where the particles in the loop have an additional U(1){sub D} gauge symmetry, which may be exact or broken to Z{sub 2}. This model is relevant to a number of astrophysical observations, including AMS-02 and the dark-matter distribution in dwarf galactic halos.
Starobinsky-Like Inflation and Neutrino Masses in a No-Scale SO(10) Model
Ellis, John
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.
New class of two-loop neutrino mass models with distinguishable phenomenology
Cao, Qing-Hong; Chen, Shao-Long; Ma, Ernest; Yan, Bin; Zhang, Dong-Ming
2018-04-01
We discuss a new class of neutrino mass models generated in two loops, and explore specifically three new physics scenarios: (A) doubly charged scalar, (B) dark matter, and (C) leptoquark and diquark, which are verifiable at the 14 TeV LHC Run-II. We point out how the different Higgs insertions will distinguish our two-loop topology with others if the new particles in the loop are in the simplest representations of the SM gauge group.
Neutrinos: Theory and Phenomenology
Energy Technology Data Exchange (ETDEWEB)
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.
International Nuclear Information System (INIS)
Pontecorvo, B.; Bilen'kij, S.
1987-01-01
After the famous 1983 discovery of intermediate W, Z 0 bosons it may be stated with certainty that W, Z 0 are entirely responsible for the production of neutrinos and for their interactions. Neutrino physics notions are presented from this point of view in the first four introductory, quite elementary, paragraphs of the paper. The following seven paragraphs are more sophisticated. They are devoted to the neutrino mass and neutrino mixing question, which is the most actual problem in today neutrino physics. Vacuum neutrino oscillations, matter neutrino oscillations and netrinoless double-decay are considered. Solar neutrino physics is discussed in some detail from the point of view of vacuum and matter neutrino oscillations. The role played by neutrinos in the Universe is briefly considered. In the last paragraph there discussed the probable observation by different groups of neutrinos connected with the Supernova 1987 A: the first observation of gravitational star collapse (at least the general rehearsal of such observation) opens up a new era in astronomy of today exerimental physics and astrophysics is presented at the end of the paper in the form of a Table
Neutrino`s helicity in a gravitational field; Helicite des neutrinos dans un champ gravitationnel
Energy Technology Data Exchange (ETDEWEB)
Pansart, J.P.
1996-12-31
By using approximated solutions of Dirac`s equation, we show that there is no helicity reversal for light neutrinos in the Schwarzschild metric nor in an expanding universe. The actual coupling between a particle spin and the angular momentum of a heavy rotating body induces a possible helicity reversal but with an unobservable probability proportional to m{sup 2}{sub p} / E{sup 2}, where m{sub p} is the particle mass and E its energy. In these calculations, the helicity is defined through the spin orientation with respect to the current and not with respect to the linear momentum. This definition gives simple expressions and is equal to the usual definition in the case of a flat space. (N.T.). 10 refs.
NEW NEUTRINO MASS BOUNDS FROM SDSS-III DATA RELEASE 8 PHOTOMETRIC LUMINOUS GALAXIES
Energy Technology Data Exchange (ETDEWEB)
De Putter, Roland [ICC, University of Barcelona (IEEC-UB), Marti i Franques 1, E-08028 Barcelona (Spain); Mena, Olga; Giusarma, Elena [Instituto de Fisica Corpuscular, University of Valencia-CSIC (Spain); Ho, Shirley; Seo, Hee-Jong; White, Martin; Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Cuesta, Antonio [Yale University, New Haven, CT (United States); Ross, Ashley J.; Percival, Will J. [Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom); Bizyaev, Dmitry; Brewington, Howard; Malanushenko, Elena; Malanushenko, Viktor; Oravetz, Daniel; Pan, Kaike; Shelden, Alaina; Simmons, Audrey [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Kirkby, David [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); 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
Acquire information about neutrino parameters by detecting supernova neutrinos
Huang, Ming-Yang; Guo, Xin-Heng; Young, Bing-Lin
2010-01-01
We consider the supernova shock effects, the Mikheyev-Smirnov-Wolfenstein (MSW) effects, the collective effects, and the Earth matter effects in the detection of type II supernova neutrinos on the Earth. It is found that the event number of supernova neutrinos depends on the neutrino mass hierarchy, the neutrino mixing angle $\\theta_{13}$, and neutrino masses. Therefore, we propose possible methods to identify the mass hierarchy and acquire information about $\\theta_{13}$ and neutrino masses ...
Explaining dark matter and neutrino mass in the light of TYPE-II seesaw model
Biswas, Anirban; Shaw, Avirup
2018-02-01
With the motivation of simultaneously explaining dark matter and neutrino masses, mixing angles, we have invoked the Type-II seesaw model extended by an extra SU(2) doublet Φ. Moreover, we have imposed a Z2 parity on Φ which remains unbroken as the vacuum expectation value of Φ is zero. Consequently, the lightest neutral component of Φ becomes naturally stable and can be a viable dark matter candidate. On the other hand, light Majorana masses for neutrinos have been generated following usual Type-II seesaw mechanism. Further in this framework, for the first time we have derived the full set of vacuum stability and unitarity conditions, which must be satisfied to obtain a stable vacuum as well as to preserve the unitarity of the model respectively. Thereafter, we have performed extensive phenomenological studies of both dark matter and neutrino sectors considering all possible theoretical and current experimental constraints. Finally, we have also discussed a qualitative collider signatures of dark matter and associated odd particles at the 13 TeV Large Hadron Collider.