Dark consequences from light neutrino condensations

Nuclear Physics B - Proceedings Supplements, 1994

Present limits on neutrino masses are briefly reviewed, along with cosmological and astrophysical hints from dark matter, solar and atmospheric neutrino observations that suggest neutrino masses.

Acta Phys.Polon., 2010

Selected topics in the theory of neutrinos, discussed in last years, are presented. We shortly summarize properties of neutrinos in frame of the original Standard Model (SM) and give the experimental information about their masses and mixing. In the frame of the model with massive neutrinos, the so-called New SM (νSM), two controversial phenomena, the Mössbauer neutrinos problem and the GSI anomaly are explained. Beyond the SM (BSM) we focus on two issues, on the problem of small neutrino masses and large mixing in comparison to the quark sector and on how neutrino oscillation phenomena should be correctly described in the BSM.

Physics of Atomic Nuclei, 2000

I discuss the implications of the latest data on solar and atmospheric neutrinos which strongly indicate the need for physics beyond the Standard Model. I review the theoretical options for reconciling these data in terms of three-neutrino oscillations. Even though not implied by the data, bi-maximal models of neutrino mixing emerge as an attractive possibility. Supersymmetry with broken R-parity provides a predictive way to incorporate it, opening the possibility of testing neutrino anomalies at high-energy collider experiments such as the LHC or at the upcoming long-baseline or neutrino factory experiments. Reconciling, in addition, the hint provided by the LSND experiment requires a fourth, light sterile neutrino. The simplest theoretical scenarios are the most symmetric ones, in which two of the four neutrinos are maximally-mixed and lie at the LSND scale, while the others are at the solar mass scale. The lightness of the sterile neutrino, the nearly maximal atmospheric neutrino mixing, and the generation of ∆m 2 ⊙ & ∆m 2 atm all follow naturally from the assumed lepton-number symmetry and its breaking. These two basic schemes can be distinguished at neutral-current-sensitive solar & atmospheric neutrino experiments such as the Sudbury Neutrino Observatory. However, underground experiments have not yet proven neutrino masses, since there is a variety of alternative mechanisms. For example, flavour changing interactions can play an important rôle in the explanation of solar and of contained atmospheric data and could be tested through effects such as µ → e + γ, µ − e conversion in nuclei, unaccompanied by neutrino-less double beta decay. Conversely, the room is still open for heavy unstable neutrinos. A short-lived ν µ might play a rôle in the explanation of the atmospheric data. Finally, in the presence of a sterile neutrino ν s , a long-lived ν τ in the MeV range could delay the time at which the matter and radiation contributions to the energy density of the Universe become equal, reducing the density fluctuations on the smaller scales, and rescuing the standard cold dark matter scenario for structure formation. In this case the light ν e , ν µ and ν s would account for the solar & atmospheric data.

Neutrino Physics in recent times has been going through a revolutionary period. Measurements of neutrinos coming from the sun or produced by cosmic rays in the Earth's atmosphere have revealed that neutrinos "oscillate", that is they change their flavor periodically with time. The observation of this phenomenon allows to obtain precious information on the neutrino masses and their mixing, shedding information about the "flavor problem", that is the origin of the fermion families and of the masses and mixing of quarks and leptons. In these lectures we introduce the subject and review these recent developments .

American Journal of Physics, 2004

We update our recent didactic survey of neutrino physics, including new results from the Sudbury Neutrino Observatory and Kamioka Liquid Scintillator Anti-Neutrino Detector experiments, and recent constraints from the Wilkinson Microwave Anisotropy Probe and other cosmological probes.

1999

I discuss the implications of the latest data on solar and atmospheric neutrinos which strongly indicate the need for physics beyond the Standard Model. I review the theoretical options for reconciling these data in terms of three-neutrino oscillations. Even though not implied by the data, bi-maximal models of neutrino mixing emerge as an attractive possibility. Supersymmetry with broken R-parity provides a predictive way to incorporate it, opening the possibility of testing neutrino anomalies at high-energy collider experiments such as the LHC or at the upcoming long-baseline or neutrino factory experiments. Reconciling, in addition, the hint provided by the LSND experiment requires a fourth, light sterile neutrino. The simplest theoretical scenarios are the most symmetric ones, in which two of the four neutrinos are maximally-mixed and lie at the LSND scale, while the others are at the solar mass scale. The lightness of the sterile neutrino, the nearly maximal atmospheric neutrino mixing, and the generation of ∆m 2 ⊙ & ∆m 2 atm all follow naturally from the assumed lepton-number symmetry and its breaking. These two basic schemes can be distinguished at neutral-current-sensitive solar & atmospheric neutrino experiments such as the Sudbury Neutrino Observatory. However, underground experiments have not yet proven neutrino masses, since there is a variety of alternative mechanisms. For example, flavour changing interactions can play an important rôle in the explanation of solar and of contained atmospheric data and could be tested through effects such as µ → e + γ, µ − e conversion in nuclei, unaccompanied by neutrino-less double beta decay. Conversely, the room is still open for heavy unstable neutrinos. A short-lived ν µ might play a rôle in the explanation of the atmospheric data. Finally, in the presence of a sterile neutrino ν s , a long-lived ν τ in the MeV range could delay the time at which the matter and radiation contributions to the energy density of the Universe become equal, reducing the density fluctuations on the smaller scales, and rescuing the standard cold dark matter scenario for structure formation. In this case the light ν e , ν µ and ν s would account for the solar & atmospheric data.

2005

The mean free path of neutrino -free electron gas interaction has been calculated by taking into account the neutrino electromagnetic form factors and the possibility of neutrino oscillation. It is shown that the form factor effect becomes significant for a neutrino magnetic moment µν ≥ 10 −10 µB and for a neutrino radius R ≥ 10 −6 MeV −1 . The mean free path is found to be sensitive to the νe − νµ and νe − ν R e transition probabilities.

Nuclear Physics B - Proceedings Supplements, 1989

Physical Review D, 2000

If neutrino masses are produced by a see-saw mechanism the Standard Model prediction for the Higgs mass window (defined by upper (perturbativity) and lower (stability) bounds) can be substantially affected. Actually the Higgs mass window can close completely, which settles an upper bound on the Majorana mass for the right-handed neutrinos, M , ranging from 10 13 GeV for three generations of quasi-degenerate massive neutrinos with mν ≃ 2 eV, to 5 × 10 14 GeV for just one relevant generation with mν ≃ 0.1 eV. A slightly weaker upper bound on M , coming from the requirement that the neutrino Yukawa couplings do not develop a Landau pole, is also discussed. PACS: 14.80.Bn, 14.60.Pq, Observations of the flux of atmospheric neutrinos by SuperKamiokande [1] provide strong evidence for neutrino oscillations, which in turn imply that (at least two species of) neutrinos must be massive. Additional support to this hypothesis is given by the need of neutrino oscillations to explain the solar neutrino flux deficit and the possible essential role of the neutrinos in the large scale structure of the universe [2]. Much work has been devoted in the last months in order to guess and to explain the structure and the origin of the neutrino mass matrices capable to account for the different observations .

The European Physical Journal C, 1999

Efforts to unify group-theoretically the standard-model gauge interactions with the generation structure of fermions and their mirror partners should be accompanied with the unification of the corresponding gauge couplings. In this paper the possibility of such a unification is studied and conclusions on possible symmetry-breaking channels and scales, as well as on the fermion content of the theory, are drawn. The breaking of some of the symmetries allows various Majorana masses for neutrinos and their mirror partners, so these are studied next. Implications to neutrino mixings and mass hierarchies in connection with recent experimental results, as well as to electroweak precision tests, are then discussed.

Physical Review D, 2009

We discuss the simplest mechanisms for generating neutrino masses at tree level and one loop level. We find a significant number of new possibilities where one can generate neutrino masses at the one-loop level by adding only two new types of representations. These models have renormalizable interactions that automatically conserve baryon number. Adding to the minimal standard model a scalar color octet with SU (3) SU (2) U (1) quantum numbers, (8, 2, 1/2), and a fermionic color octet in the fundamental or adjoint representation of SU (2) one can generate neutrino masses in agreement with experiment. Signals at the LHC, and constraints from flavour violation are briefly discussed.

Physical Review D, 2020

We discuss the possibility to distinguish between Dirac and Majorana neutrinos in the context of the minimal gauge theory for neutrino masses, the B − L gauge extension of the Standard Model. We revisit the possibility to observe lepton number violation at the Large Hadron Collider and point out the importance of the decays of the new gauge boson to discriminate between the existence of Dirac or Majorana neutrinos.

Neutrino Physics - Its Impact on Particle Physics, Astrophysics and Cosmology - Proceedings of the Carolina Symposium on Neutrino Physics, 2001

Since their "discovery" by Pauli in 1930, neutrinos have played a key part in confirmation of the structure of the standard model of strong and electroweak interactions. After reviewing ways in which this has been manifested in the past, we discuss areas in which neutrinos continue to play this role.

Reports on Progress in Physics, 2007

During 2004, four divisions of the American Physical Society commissioned a study of neutrino physics to take stock of where the field is at the moment and where it is going in the near and far future. Several working groups looked at various aspects of this vast field. The summary was published as a main report entitled "The Neutrino Matrix" accompanied by short 50 page versions of the report of each working group. Theoretical research in this field has been quite extensive and touches many areas and the short 50 page report [1] provided only a brief summary and overview of few of the important points. The theory discussion group felt that it may be of value to the community to publish the entire study as a white paper and the result is the current article. After a brief overview of the present knowledge of neutrino masses and mixing and some popular ways to probe the new physics implied by recent data, the white paper summarizes what can be learned about physics beyond the Standard Model from the various proposed neutrino experiments. It also comments on the impact of the experiments on our understanding of the origin of the matter-antimatter asymmetry of the Universe and the basic nature of neutrino interactions as well as the existence of possible additional neutrinos. Extensive references to original literature are provided.

Springer Tracts in Modern Physics, 2000

A review of the problem of neutrino mass, mixing and oscillations is given. Possible phenomenological schemes of neutrino mixing are discussed. The most important consequences of neutrino mixing-neutrino oscillations are considered in some details. The data of atmospheric, solar and LSND experiments are discussed. The results of phenomenological analyses of the data under the assumption of the mixing of three and four massive neutrinos are shortly presented.