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

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

Supersymmetry constraints on the neutrino mass

Within the minimal supersymmetric extension of the Standard Model, the one-photon decay of the neutrino is studied on the basis of astrophysical, cosmological, and experimental data. Limits on the neutrino masses are obtained.     

Texture zeros and majorana phases of the neutrino mass matrix

We present the generic formulas to calculate the ratios of neutrino masses and the Majorana phases of CP violation from the neutrino mass matrix with two independent vanishing entries in the flavor basis where the charged lepton mass matrix is diagonal. An order-of-magnitude illustration is given for seven experimentally acceptable textures of the neutrino mass matrix, and some analytical approximations are made for their phenomenological consequences at low energy scales.     

Primary cosmic ray flux

We discuss the primary cosmic ray flux from the point of view of particle interactions and production of atmospheric neutrinos. The overall normalization of the cosmic ray flux and its time variations and site dependence are major ingredients of the atmospheric neutrino predictions and the basis for the derivation of the neutrino oscillation parameters.     

A covariant path amplitude description of flavour oscillations: the Gribov-Pontecorvo phasefor neutrino vacuum propagation is right

An extended study is performed of geometrical and kinematical assumptions used in calculations of the neutrino oscillation phase. The almost universally employed "equal velocity" assumption, in which all neutrino mass eigenstates are produced at the same time, is shown to underestimate, by a factor of two, the neutrino propagation contribution to the phase. Taking properly into account, in a covariant path amplitude calculation, the incoherent nature of neutrino production as predicted by the standard model, results in an important source propagator contribution to the phase. It is argued that the commonly discussed Gaussian "wave packets" have no basis within quantum mechanics and are the result of a confused amalgam of quantum and classical wave concepts.Received: 15 November 2002, Published online: 29 August 2003     

Spin-flavor oscillations of neutrinos in rapidly varying external fields

Spin-flavor oscillations of neutrinos in rapidly varying external fields are studied. A method for describing neutrino oscillations in arbitrary rapidly varying external fields is developed. An effective Hamiltonian that describes the evolution of the averaged neutrino wave function is obtained. Neutrino oscillations in rapidly varying magnetic fields are considered on the basis of the general formalism developed in this study. Neutrino transitions in a superposition of a constant and a rotating (in space) magnetic field that are transverse with respect to the neutrino velocity are studied. The probabilities of transitions in spin-flavor oscillations of neutrinos in the magnetic fields of the Sun are estimated. Numerical solutions to the Schrödinger equation for the Hamiltonian that describes neutrino interaction with a constant and a rotating (in space) magnetic field are given. It is shown that the approximate analytic formula obtained in the present study for the probability of neutrino transitions is consistent with the respective numerical solution to the evolution equation at high frequencies of the rotating magnetic fields.     

夸克物质中的色超导性理论简介

夸克-夸克通过单胶子交换的相互作用在其反对称态上是相互吸引的,在致密夸克物质里,这种吸引相互作用会导致费米面上的双夸克凝聚,这就是所谓的夸克配对或色超导现象。本文介绍了夸克配对或色超导现象的基本知识和一些新进展。色超导是一个对称性自发破坏现象,有非常丰富的破缺方式,我们介绍了色超导对称性及其自发破坏模式的分析方法,介绍了怎样计算色超导体两个最基本的变量：能隙和迈斯纳质量。然后我们介绍了描述色超导现象的有效理论。最后是这些理论的一个应用,即计算色超导体里的中微子发射率以及其它输运性质。本文可以作为研究夸克物质理论的入门参考资料。     

Leptogenesis and dark matter unified in a non-SUSY model for neutrino masses

We propose a unified explanation for the origin of dark matter and baryon number asymmetry on the basis of a non-supersymmetric model for the neutrino masses. Neutrino masses are generated in two distinct ways, that is, a tree-level seesaw mechanism with a single right-handed neutrino, and one-loop radiative effects by a new additional doublet scalar. A spontaneously broken U(1)^′ brings about a Z₂ symmetry which restricts couplings of this new scalar and controls the neutrino masses. It also guarantees the stability of a CDM candidate. We examine two possible candidates for the CDM. We also show that the decay of a heavy right-handed neutrino related to the seesaw mechanism can generate baryon number asymmetry through leptogenesis.     

Magnetic neutrino scattering on atomic electrons revisited

We reexamine the role of electron binding effects in the inelastic neutrino–atom scattering induced by the neutrino magnetic moment. The differential cross section of the process is presented as a sum of the longitudinal and transverse components, according to whether the force that the neutrino magnetic moment exerts on electrons is parallel or perpendicular to momentum transfer. The atomic electrons are treated nonrelativistically. On this basis, the recent theoretical predictions concerning the magnetic neutrino-impact ionization of atoms are critically discussed. Numerical calculations are performed for ionization of a hydrogenlike Ge⁺³¹ ion by neutrino impact.     

Atmospheric Neutrinos as a Tool for Exploring the Earth’s Inner Parts

Investigation of the Earth’s inner parts requires developing new methods. It is well known that atmospheric neutrinos traverse the Earth, undergoing virtually no interaction. The change in the neutrino flux is due exclusively to neutrino oscillations, which are enhanced by the effect of Earth’s matter. At the present time, there are two projects outside Russia (PINGU and ORCA) that are aimed at detecting atmospheric neutrinos that traversed the Earth, which are supposed to be used for purposes of Earth’s tomography. The creation of a large neutrino detector on the basis of a liquid scintillator is planned at the BaksanNeutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) in the North Caucasus. After testing this detector, there will arise the possibility of employing it as part of the worldwide network of neutrino detectors for studying the Earth’s inner parts.     

Non-standard Hamiltonian effects on neutrino oscillations

We investigate non-standard Hamiltonian effects on neutrino oscillations, which are effective additional contributions to the vacuum or matter Hamiltonian. Since these effects can enter in either the flavor or mass basis, we develop an understanding of the difference between these bases representing the underlying theoretical model. In particular, the simplest of these effects are classified as “pure” flavor or mass effects, where the appearance of such a “pure” effect can be quite plausible as a leading non-standard contribution from theoretical models. Compared to earlier studies investigating particular effects, we aim for a top–down classification of a possible “new physics” signature at future long-baseline neutrino oscillation precision experiments. We develop a general framework for such effects with two neutrino flavors and discuss the extension to three neutrino flavors, and we demonstrate the challenges for a neutrino factory to distinguish the theoretical origin of these effects with a numerical example as well. We find how the precision measurements of neutrino oscillation parameters can be altered by non-standard effects alone (not including non-standard interactions in the creation and detection processes) and that the non-standard effects on Hamiltonian level can be distinguished from other non-standard effects (such as neutrino decoherence and decay) if we consider the specific imprint of the effects on the energy spectra of several different oscillation channels at a neutrino factory.     

夸克物质中的色超导性理论简介(英文)

夸克-夸克通过单胶子交换的相互作用在其反对称态上是相互吸引的,在致密夸克物质里,这种吸引相互作用会导致费米面上的双夸克凝聚,这就是所谓的夸克配对或色超导现象。本文介绍了夸克配对或色超导现象的基本知识和一些新进展。色超导是一个对称性自发破坏现象,有非常丰富的破缺方式,我们介绍了色超导对称性及其自发破坏模式的分析方法,介绍了怎样计算色超导体两个最基本的变量:能隙和迈斯纳质量。然后我们介绍了描述色超导现象的有效理论。最后是这些理论的一个应用,即计算色超导体里的中微子发射率以及其它输运性质。本文可以作为研究夸克物质理论的入门参考资料。     

Some new symmetric relations and prediction of left-and right-handed neutrino masses using Koide's relation

The masses of the three generations of charged leptons are known to completely satisfy Koide's mass relation,but the question remains of whether such a relation exists for neutrinos.In this paper,by considering the seesaw mechanism as the mechanism generating tiny neutrino masses,we show how neutrinos satisfy Koide's mass relation,on the basis of which we systematically give exact values of both left-and right-handed neutrino masses.     

Mass properties of active and sterile neutrinos in a phenomenological (3 + 1 + 2) model

A generalized model involving three active neutrinos and three sterile neutrinos of different mass, one being relatively heavy [(3 + 1 + 2) model], is considered on the basis of experimental data, which admit the existence of anomalies beyond the minimally extended standard model featuring three active neutrinos of different mass. Basic properties used to describe massive active and sterile neutrinos are studied along with methods for determining the absolute scale of neutrino masses and for estimating neutrino masses on the basis of available experimental data. In the approximation of CP conservation, admissible values of the elements of the neutrino mass matrix are found from numerical calculations versus the possible values of the mass of one of the sterile neutrinos. The dependences of the mass properties of the neutrinos on the sterile-neutrino mass are constructed with allowance for possible sterile-neutrino contributions. The respective results can be used to interpret and predict results of various neutrino experiments.     

Neutrinos in general relativity: Four(?) levels of approach

The three subsequent levels of approach to the problem of the neutrino in general relativity which have been exploited till now, are:

1. ‘classical particle’ approach, i.e. a study on the neutrino as a classical particle in a classical, given gravitational field;
2. ‘quantum particle’ approach, i.e. considering the Dirac equation for the neutrino in a given gravitational field;
3. ‘classical field’ approach comprising the study of combined neutrino-gravitational fields.

Many results obtained along these lines are presented, with emphasis upon the geometrical theory of two-component neutrino-gravitational fields. A synthesis of the particle and fields aspects of the neutrino could provide a possible fourth, till now non-existing, ‘quantum field’ level of approach. This should deal with a guantized neutrino field in a curved space-time (which might be also quantized, but perhaps this should belong already to a next, fifth level of approach). Studies on the neutrino physics in gravitational fields reveal not only a series of results which are of interest in se, and which may be used as the basis to a unified theory of neutrino and gravitational fields (the Rainich problem for the neutrino). They provide in addition the necessary material for astrophysical and cosmological applications; some of these are outlined in relation to the results presented.     

Large-volume detector at the Baksan Neutrino Observatory for studies of natural neutrino fluxes for purposes of geo- and astrophysics

At the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences, Moscow) deployed in the Caucasus mountains, it is proposed to create, at a depth corresponding to 4760 mwe, a large-volume neutrino detector on the basis of a liquid scintillator with a target mass of 10 kt. The detector in question is intended for recording natural fluxes of neutrinos whose energy may be as low as 100MeV. Neutrino fluxes from various sources are considered in the present study, and the expected effect in the proposed detector is estimated. The detector hat is being developed at the Baksan Neutrino Observatorywill become part of the world network of neutrino detectors for studying natural neutrino fluxes.     

Neutrino emission of supercritical quasi-atom

On the basis of the theory of electrically weak Weinberg-Salam interactions, the emission of neutrino pairs by a relativistic lepton moving in a electrical undulator is investigated. A relativistic lepton undergoing motion of undulator type is interpreted as a relativistic quasi-atom, which generates electron neutrino radiation sufficiently rapidly for experimental observation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 16–21, March, 1988.     

Neutrino self-energy operator and neutrino magnetic moment

A simple method for calculating the magnetic moment of a massive neutrino on the basis of its self-energy operator is presented. An expression for the magnetic moment of a massive neutrino in an external electromagnetic field is obtained in the R _ξ gauge for the case of an arbitrary ratio of the lepton and W-boson masses.     

75Se as a new neutrino source for calibrating low-threshold detectors of solar neutrinos

A new artificial neutrino source on the basis of the ⁷⁵Se isotope for calibrating low-threshold solar-neutrino detectors like GNO, SAGE, and LENS is considered. It is shown that ⁷⁵Se possesses some advantages over sources based on ⁵¹Cr: the energies of its basic neutrino lines are close to the endpoint of the neutrino spectrum associated with proton-proton interactions in the solar cycle, and the production cross section for the former and its half-life are much larger. A Russian L-2 heavy-water reactor can be used to generate the required activity of ⁷⁵Se in an optimal mode.     

Experimental limits on axion production and interaction cross sections,and decay rate

Limits on axion production in proton interactions at 26 GeV are given on the basis of some results of the Gargamelle neutrino experiment at the CERN PS.