Non-standard neutrino properties

A discussion of several exotic models and how well they are able to describe the data, with particular emphasis on atmospheric neutrinos.     

Weak neutral currents and neutrino electromagnetic properties

The phenomenological Hamiltonian for weak lepton interaction that contains, along with a charged current V-A interaction, a neutral current V-A interation and the dispersion method are used to study the effect of lepton and nucleon currents on the electromagnetic properties of the neutrino. Expressions are obtained for the neutrino formfactor F(q²) when it satisfies the dispersion relations without subtraction and with one subtraction.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 43–48, May, 1977.     

Matter–antimatter asymmetry and neutrino properties

The cosmological baryon asymmetry can be explained as remnant of heavy Majorana neutrino decays in the early universe. We study this mechanism for two models of neutrino masses with a large ν_μ−ν_τ mixing angle which are based on the symmetries SU(5)×U(1)_F and SU(3)_c×SU(3)_L×SU(3)_R×U(1)_F, respectively. In both cases B−L is broken at the unification scale Λ_GUT. The models make different predictions for the baryogenesis temperature and the gravitino abundance.     

Cosmology

Precise astronomical observations of the cosmic expansion and the anisotropies of the cosmic microwave background have confirmed the simple cosmological “big bang” models. They have also produced evidence for a strange composition of the cosmic matter and energy density. The known baryons contribute only 5 percent to the cosmic substrate, while 25 percent are due to unknown dark matter particles, and 70 percent seem to come from a mysterious dark energy component which presently acts like a cosmological constant accelerating the cosmic expansion.     

General neutrino mass spectrum and mixing properties in seesaw mechanisms

Neutrinos stand out among the elementary particles because of their unusually small masses.Various seesaw mechanisms attempt to explain this fact.In this work,applying insights from matrix theory,we are in a position to treat variants of seesaw mechanisms in a general manner.Specifically,using Weyl's inequalities,we discuss and rigorously prove under which conditions the seesaw framework leads to a mass spectrum with exactly three light neutrinos.We find an estimate of the mass of heavy neutrinos to be the mass obtained by neglecting light neutrinos,shifted at most by the maximal strength of the coupling to the light neutrino sector.We provide analytical conditions allowing one to prescribe that precisely two out of five neutrinos are heavy.For higher-dimensional cases the inverse eigenvalue methods are used.In particular,for the CP-invariant scenarios we show that if the neutrino sector has a valid mass matrix after neglecting the light ones,i.e.if the respective mass submatrix is positive definite,then large masses are provided by matrices with large elements accumulated on the diagonal.Finally,the Davis-Kahan theorem is used to show how masses affect the rotation of light neutrino eigenvectors from the standard Euclidean basis.This general observation concerning neutrino mixing,together with results on the mass spectrum properties,opens directions for further neutrino physics studies using matrix analysis.     

Astrophysics and Cosmology

The Review summarizes much of particle physics and cosmology.Using data from previous editions,plus 3,062 new measurements from 721 papers,we list,evaluate,and average measured properties of gauge bosons and the recently discovered Higgs boson,leptons,quarks,mesons,and baryons.We summarize searches for hypothetical particles such as supersymmetric particles,heavy bosons,axions,dark photons,etc.All the particle properties and search limits are listed in Summary Tables.We also give numerous tables,figures,formulae,and reviews of topics such as Higgs Boson Physics,Supersymmetry,Grand Unified Theories,Neutrino Mixing,Dark Energy,Dark Matter,Cosmology,Particle Detectors,Colliders,Probability and Statistics.Among the 117 reviews are many that are new or heavily revised,including new reviews on Pentaquarks and Inflation.     

Fast neutrino decay and solar neutrino detectors

The neutrino decay solution of the solar neutrino problem is revisited in the context of majoron models. It is shown that for a definite range of parameters this scenario reconciles both the Homestake and the Kamiokande data. The prediction for Gallium detectors is also given. Attention is devoted to the analysis of the signal, which is the crucial prediction of this scenario. It is shown that the sensitivity of Borexino is sufficient to observe this signal and to distinguish it from the alternative signal provided by hybrid models of neutrino oscillation and magnetic moment transitions. Other sources of solar production are also reviewed (matter induced decay, MSW catalized decay or the decay of solar 17 keV neutrinos).     

Post-Newtonian Cosmology

Newtonian Cosmology is commonly used in astrophysical problems, because of its obvious simplicity when compared with general relativity. However it has inherent difficulties, the most obvious of which is the non-existence of a well-posed initial value problem. In this paper we investigate how far these problems are met by using the post-Newtonian approximation in cosmology.     

Scaling Cosmology

We show that with the help of a suitable coupling between dark energy and cold dark matter it is possible to reproduce any scaling solution _{X M} a , where _X and _M are the densities of dark energy and dark matter, respectively. We demonstrate how the case = 1 alleviates the coincidence problem. Future observations of supernovae at high redshift as well as quasar pairs which are planned to discriminate between different cosmological models will also provide direct constraints on the coupling between dark matter and dark energy.     

Magnetohydrodynamics and Plasma Cosmology

We study the linear magnetohydrodynamic (MHD) equations, both in the Newtonian and the general-relativistic limit, as regards a viscous magnetized fluid of finite conductivity and discuss instability criteria. In addition, we explore the excitation of cosmological perturbations in anisotropic spacetimes, in the presence of an ambient magnetic field. Acoustic, electromagnetic (e/m) and fast-magnetosonic modes, propagating normal to the magnetic field, can be excited, resulting in several implications of cosmological significance.     

Cosmology and new physics

A comparison of the standard models in particle physics and in cosmology demonstrates that they are not compatible, though both are well established. The basics of modern cosmology are briefly reviewed. It is argued that the measurements of the main cosmological parameters are achieved through many independent physical phenomena and this minimizes possible interpretation errors. It is shown that astronomy demands new physics beyond the frameworks of the (minimal) standard model in particle physics. More revolutionary modifications of the basic principles of the theory are also discussed. The text was submitted by the authors in English.     

Baryogenesis via Sterile neutrino oscillation and neutrino parameters

We investigate baryogenesis in the νMSM which is the Minimal Standard Model (MSM) extended by three right-handed neutrinos with Majorana masses being smaller than the weak scale. In this model three sterile neutrinos, which are almost right-handed states, play important roles in cosmology. The baryon asymmetry of the universe (BAU) is generated via mechanism through flavor oscillation between two sterile neutrinos N₂ and N₃ which are degenerate in masses. We consider the case when BAU is solely originated from the CP violating phases in the mixing matrix of active neutrinos, i.e., the Dirac phase δ and the Majorana phase η, and study how BAU depends on these CP violating phases.     

Cosmology and fundamental physics

Connections between fundamental physics and cosmology are discussed.