Supernova constraints on neutrino mass and mixing

In this article I review the constraints on neutrino mass and mixing coming from type-II supernovae. The bounds obtained on these parameters from shock reheating, r-process nucleosynthesis and from SN1987A are discussed. Given the current constraints on neutrino mass and mixing the effect of oscillations of neutrinos from a nearby supernova explosion in future detectors will also be discussed.     

SNO results and neutrino magnetic moment solution to the solar neutrino problem

We have analysed the solar neutrino data obtained from chlorine, gallium and Super-Kamiokande (SK) experiments (1258 days) and also the new results that came from Sudbury Neutrino Observatory (SNO) charge current (CC) and elastic scattering (ES) experiments considering that the solar neutrino deficit is due to the interaction of neutrino transition magnetic moment with the solar magnetic field. We have also analysed the moments of the spectrum of scattered electrons at SK. Another new feature in the analysis is that for the global analysis, we have replaced the spectrum by its centroid.     

Analysis of neutrino mass, mixing and flavor change

Established results on neutrino mass, mixing and flavor change (as of 2009) are briefly reviewed. Status and prospects of unknown neutrino properties (smallest mixing angle, Dirac/Majorana nature, absolute masses and their hierarchy) are also discussed.     

Supernova neutrino detection by terrestrial nuclear detectors

We present and discuss differential cross sections for the ^128,130Te isotopes, contents of the COBRA double beta decay detector. The response of these isotopes to energy spectra of supernova neutrinos is explored by convoluting the original results, calculated in the context of the quasi-particle random phase approximation (QRPA) using realistic two-body forces, with a two-parameter Fermi-Dirac (FD) and a Power-Law (PL) neutrino energy distributions.     

Analysis of the data recorded by the Mont Blanc neutrino detector and by the Maryland and Rome gravitational-wave detectors during SN1987A

Summary The data recorded by the gravitational wave and the neutrino detectors mentioned in the title have been analysed over a period of several days that includes the Mont Blanc 5ν burst occurrence time. A correlation is found during a period of about two hours roughly centred on the 5ν burst, independently between Maryland and Mont Blanc and Rome and Mont Blanc. The probability that these two correlations be due to chance is of the order of between 10⁻⁶ and 10⁻⁵. It is found that this effect is mainly due to a dozen of large Maryland and Rome events distributed during the above two-hour period.

---

Riassunto I dati registrati con le antenne gravitazionali ed i rivelatori di neutrini indicati nel titolo sono stati analizzati in un periodo di vari giorni, includendo il tempo di occorrenza dell'evento di 5 neutrini rivelato al Monte Bianco. è stata trovata una correlazione durante circa due ore centrata al tempo dei 5ν, indipendentemente Maryland/Monte Bianco e Roma/Monte Bianco. La probabilità che queste due correlazioni siano dovute al caso è dell'ordine di 10⁻⁶÷10⁻⁵. è stato trovato che questo effetto è dovuto essenzialmente ad una dozzina di segnali registrati a Roma e in Maryland durante il sopramenzionato periodo di due ore.

---

Резюме Проводится анализ данных, зарегистрированных нейтринным детектором на Мон Блане и детекторами гравитационных волн в Мэриленде и Риме, за период, охватывающий несколько дней, которые включают время появления 5ν вспышки на Мон Блане. Обнаружена корреляция в течение приблизительно двух часов, центр которой приблизительно совпадает со временем 5ν вспышки, независимо в данных Мэриленд и Мон Блан и в данных Рим и Мон Блан. Вероятность того, что эти две корреляции являются случайными, имеет порядок величины 10⁻⁶÷10⁻⁵. Обнаружено, чтот эффект обусловлен в основном дюжиной сигналов, зарегистрированных в Риме и Мэриленде в течение периода около двух часов.

     

Explaining LSND and MiniBooNE using altered neutrino dispersion relations

We investigate the possibility of explaining the MiniBooNE anomaly using CPT-and Lorentz-symmetry-violating neutrino-antineutrino oscillations in a two-generation framework. We work with four non-zero CPT-violating parameters that allow for resonant enhancements in neutrino-antineutrino oscillation phenomena in vacuo which are suitably described in terms of charge conjugation eigenstates of the system. We study the relations among the flavor, charge conjugation and mass eigenbases of neutrino-antineutrino oscillations and examine the interplay between the available CPT-violating parameter space and possible resonance structures.     

BBN constraints on neutrino and CNB

We discuss the BBN constraints on neutrino characteristics and the cosmic neutrino background in the case of neutrino oscillations. The general cases of non-zero initial population of the sterile state and non-zero lepton asymmetry are discussed as well.     

A simple method to estimate the magnetic moment of magnetic micro-particles

Micro-particles in suspension in a fluid are an example of a very low Reynolds number problem. In this case, no inertial effects are observed. Magnetic micro-particles with magnetic moment m, suspended in a fluid orient to applied external magnetic fields B due to the interaction between the field and the magnetic moment. In this work, we present a simple method to estimate the total magnetic moment of magnetic micro-organisms. The method is based on the application of an external oscillating magnetic field in the sites where the micro-organisms are. In this case, it is possible to obtain theoretically the solution of the equation of motion (rotation of the organism and its trajectory). The solution is a transcendental equation relating the orientation angle and m and can be solved by numerical methods. Changing the frequency and/or the field intensity, it is possible to obtain a situation in which the crystal rotates uninterruptedly (a resonance regime). This condition is related to the applied field intensity, to the frequency, to the medium viscosity, to the crystal dimension, and to the micro-crystal magnetic moment m. The method can be used to estimate the total cellular magnetic moment of magnetic micro-particles.     

Magnetic moment of phonons in graphene induced by a magnetic field

A magnetic field not only changes the electronic structure in graphene but also affects the phonon excitations via the electron-phonon interaction and even enables the phonons to generate magnetism. In this paper, we evaluate the magnetic moment of phonons in graphene using a generating-functional technique. The calculation results indicate that the phonon magnetic moment exists only in a weak magnetic field. The step-like change of the magnetic moment with the magnetic field reflects a macroscopic quantum effect.     

Two-loop Majorana neutrino mass and magnetic moment in a gauge model

Two-loop contributions to Majorana mass and transition magnetic moment in a gauge model not in conflict with decaying neutrino dark matter (DDM) hypothesis have been studied. Another variant of an earlier model [J Dhar and S Dev,Pramana — J. Phys. 39 541 (1992)] consistent with the DDM hypothesis is proposed and is shown to lead to large enough neutrino magnetic moment and consistent with the phenomenological constraints on neutrino mass.     

High energy neutrino absorption by W production in a strong magnetic field

An influence of a strong external magnetic field on the neutrino self-energy operator is investigated. The width of the neutrino decay into the electron and W boson, and the mean free path of an ultra-high energy neutrino in a strong magnetic field are calculated. A kind of energy cutoff for neutrinos propagating in a strong field is defined.     

Constraining WIMP magnetic moment from CDMS II experiment

We consider a degenerate or a nearly degenerate dark matter sector where a sizable magnetic moment of a (almost) Dirac type neutral dark matter candidate N is anticipated. Then, due to soft photon exchange, the cross-section in direct detection of N   can be enhanced at low Q²$Q^2$ region. We discuss the implication of this type of models in view of the recent CDMS II report.     

电矩张量与旋转带电体的磁矩

基于旋转带电体的磁矩与刚体转动惯量之间的类比关系,引入带电体的一个不同于电四极矩的电矩张量的概念,进而引入标量电矩二次曲面及电矩主轴的概念,借助正交变换及电矩张量矩阵的本征值理论,推导出沿任意方向定轴旋转带电体的磁矩的计算公式及电矩张量的若干性质,并举例说明.     

Majorana neutrino transition magnetic moment in a variant of Zee model with horizontal symmetry

A SU(2) _H symmetric variant of Zee model of lepton flavor 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.     

磁场及磁矩的测量实验

对地磁水平分量测量实验加以改进,将其扩充为能够测量亥姆霍兹线圈磁场分布和磁针的转动惯量以及磁针磁矩的实验.使其成为一个综合性较强,适用于开展研究性实验的项目.     

运动介质的电偶极矩与磁矩

在推导出介质的极化强度与磁化强度的坐标变换公式的基础上,分析导出了运动介质的电偶极矩与磁矩.     

Space-Time Fluctuations Induced by D-Branes and Their Effects on Neutrino Oscillations

Neutrino oscillations are analyzed in the Ellis-Mavromatos-Nanopoulos-Volkov (ENMV) model, where the quantum gravitational fluctuations of the space-time background are described by virtual D branes. Such fluctuations may induce neutrino oscillations if a violation of the equivalence principle or a tiny violation of the Lorentz invariance is imposed. In this framework, the oscillation length of neutrinos turns out to be proportional to E ^–2 M, where E is the neutrino energy and M is the energy which is the scale characterizing the topological fluctuations in the vacuum.     

基于SQUID梯度计的单磁源定位及磁矩反演误差分析

磁源定位及磁矩反演技术在空间探测、无损检测以及目标追踪等领域有着广泛的应用前景。利用磁场梯度张量信息进行磁源定位及磁矩反演的思想是在1975年首次提出的,2006年提出的磁性目标线性方程定位方法以其快速准确求解的特点而备受关注。但是,对于该梯度张量矩阵求逆法进行磁源定位的全方位的误差分析仍有待完善。在简要回顾梯度张量矩阵求逆法进行磁源定位的方法的基础上,提出了一种基于该方法的系统误差和随机误差分析的理论;研究结果表明定位误差是由于将差分近似为微分而引起的系统误差和传感器测量的随机误差构成。以目前具有超高精度、超高灵敏度的超导量子干涉仪作为典型磁场测量传感器,分析了梯度张量矩阵求逆法进行磁源定位及磁矩反演误差与传感器分辨率和相对误差水平之间的关系。     

First-principles study of single intrinsic vacancy formation and its effect on the electronic density states and magnetic moment of V-doped ZnO

We calculated the formation energy of single vacancy in V-doped ZnO in different conditions (oxygen or zinc rich) by first principles. Effect of an intrinsic vacancy on the electronic density of states and magnetic moment of V-doped ZnO (Zn₁₅VO₁₆) with and without single vacancy was also calculated. Our calculation was performed by the CASTEP program within spin-polarized GGA approximation implemented in materials studio software. The formation energy showed that oxygen vacancy inclined to stay far from vanadium (V) and zinc vacancy preferred to stay at a position near V. The calculated formation energy also showed that a zinc vacancy may automatically occur but an oxygen vacancy may not appear automatically. Vanadium doping introduced spin-polarization around Fermi level. For an energy favorable vacancy, an oxygen vacancy had little effect on the electronic density of states. A zinc vacancy made the spin-polarization peaks around Fermi level broaden and decreased their magnitude. For the magnetic moment in energy favorable configurations, an oxygen vacancy had little effect on the magnetic moment; a zinc vacancy significantly decreased the magnetic moment (as high as 63.7%). Changes in magnetic moments were consistent with electronic density of states. Our calculation may interpret various experimental magnetic moment values. Our work also provided a reference for preparing V-doped ZnO-based dilute magnetic semiconductors.