Quantum Mechanics of Neutrino Oscillations

We present a simple but general treatment of neutrino oscillations in the framework of quantum mechanics, using plane waves and intuitive wave packet principles when necessary. We attempt to clarify some confusing statements that have recently appeared in the literature.     

Distinguishable RGE Running Effects Between Dirac Neutrinos and Majorana Neutrinos with Vanishing Majorana CP-Violating Phases

In a novel parametrization of neutrino mixing and in the approximation of т-lepton dominance, we show that the one-loop renormalization-group equations (RGEs) of Dirac neutrinos are different from those of Majorana neutrinos even if two Majorana CP-violating phases vanish. As the latter can keep vanishing from the electroweak scale to the typical seesaw scale, it makes sense to distinguish between the RGE running effects of neutrino mixing parameters in Dirac and Majorana cases. The differences are found to be quite large in the minimal supersymmetric standard model with sizable tanβ, provided the masses of three neutrinos are nearly degenerate or have an inverted hierarchy.     

Distinguishable RGE Running Effects Between Dirac Neutrinos and Majorana Neutrinos with Vanishing Majorana CP-Violating Phases

In a novel parametrization of neutrino mixing and in the approximation of τ-lepton dominance, we show that the one-loop renormalization-group equations （RGEs） of Dirac neutrinos are different from those of Majorana neutrinos even if two Majorana CP-violating phases vanish. As the latter can keep vanishing from the electroweak scale to the typical seesaw scale, it makes sense to distinguish between the RGE running effects of neutrino mixing parameters in Dirac and Majorana cases. The differences are found to be quite large in the minimal supersymmetric standard model with sizable tan β, provided the masses of three neutrinos are nearly degenerate or have an inverted hierarchy.     

Nuclear Responses for Neutrinos and Mo Observatory of Neutrinos

Nuclear responses for neutrinos and neutrino studies in Mo nuclei are briefly reported. Nuclear spin-isospin responses for neutrinos are crucial for neutrino studies in nuclei. Spin-isospin responses for solar neutrinos, supernova neutrinos and neutrinos involved in double-beta decays are discussed. It is of great interest to study neutrino masses and low energy solar neutrinos. It is shown that it is possible to carry out with ¹⁰⁰Mo both spectroscopic studies of double-beta decays with the sensitivity of the order of m 0.03eV and real-time exclusive studies of the low energy solar neutrinos.     

Singletons,Physics in AdS Universe and Oscillations of Composite Neutrinos

The study starts with the kinematical aspects of singletons and massless particles. It extends to the beginning of a field theory of composite elementary particles and its relations with conformal field theory, including very recent developments and speculations about a possible interpretation of neutrino oscillations and CP violation in this context. This framework was developed during the past twenty years. Based on our deformation philosophy of physical theories, it deals with elementary particles composed of singletons in anti-De Sitter spacetime.     

Muon与Tau中微子的运动学有效质量及其不可探测性

利用最新的WMAP观测数据推导出电子、Muon和Tau中微子的运动学有效质量的一般上限:e2+μ2+τ2=m12+m22+m32<0.5eV2,或α<0.71eV(其中α=e,μ,τ)。考虑现有中微子振荡的实验数据,进一步得到e<0.24eV以及μ≈τ<0.24eV. 因此有效质量_μ和_τ太小而无法被探测.     

中微子振荡与中微子的静止质量

简要回顾了中微子的发现过程,论述了中微子的基本性质及三种不同类型的中微子,讨论了中微子振荡的最新实验结果及其与中微子静止质量的关系,指出了中微子的静止质量在物理学与天文学中的重要性以及确定中微子的静止质量有待进一步解决的问题。     

Neutrinos in a Vacuum Dominated Cosmology

We explore the dynamics of neutrinos in a vacuum dominated cosmology. First we show that such a geometry will induce a phase change in the eigenstates of a massive neutrino and we calculate the phase change. We also calculate the delay in the neutrino flight times in this geometry. Applying our results to the presently observed background vacuum energy density, we find that for neutrino sources further than 1.5 Gpc away both effects become non-trivial, being of the order of the standard relativistic corrections. Such sources are within the observable Hubble Deep Field. The results which are theoretically interesting are also potentially useful, in the future, as detection techniques improve. For example such effects on neutrinos from distant sources like supernovae could be used, in an independent method alternative to standard candles, to constrain the dark energy density and the deceleration parameter. The discussion is extended to investigate Caianiello's inertial or maximal acceleration (MA) effects of such a vacuum dominated spacetime on neutrino oscillations. Assuming that the MA phenomenon exists, we find that its form as generated by the presently observed vacuum energy density would still have little or no measurable effect on neutrino phase evolution, for neutrinos in the energy range of a few eV.     

Lorentz Covariant Canonical Formalism for Free Massive, Massless and Tachyonic Particles

We construct a consistent Lorentz-covariant canonical formalism for a free massive, massless and tachyonic particle in the framework of the absolute synchronization scheme of clocks. In the case of a massive particle our approach is canonically equivalent to the standard formulation which is not manifestly covariant. The absolute synchronization scheme seems to be the only one we can apply in the case of massless and tachyonic particles.     

Massive and massless neutrinos on unbalanced seesaws

The observation of neutrino oscillations requires new physics beyond the standard model (SM). A SM-like gauge theory with p lepton families can be extended by introducing q heavy right-handed Majorana neutrinos but preserving its SU(2)_L×U(1)_Y gauge symmetry. The overall neutrino mass matrix M turns out to be a symmetric (p+q)×(p+q) matrix. Given p>q, the rank of $M$ is in general equal to 2q,corresponding to 2q non-zero mass eigenvalues. The existence of (p-q) massless left-handed Majorana neutrinos is an exact consequence of the model, independent of the usual approximation made in deriving the Type-I seesaw relation between the effective p×p light Majorana neutrino mass matrix M_ν and the q×q heavy Majorana neutrino mass matrix M_R. In other words, the numbers of massive left- and right-handed neutrinos are fairly matched. A good example to illustrate this "seesaw fair play rule" is the minimal seesaw model with p=3 and q=2, in which one massless neutrino sits on the unbalanced seesaw.     

India-based Neutrino Observatory (INO)

We present some physics possibilities with an iron calorimeter detector (ICAL) and a status report on the feasibility study to construct such a detector at a future possible India-based Neutrino Observatory (INO). This talk was given at the workshop on high energy physics phenomenology, WHEPP-8, in Jan. 2004, at IIT Bombay.     

Singletons and Neutrinos

The first half is a rapid review of 30 years of work on physics in anti-de Sitter space, with heavy emphasis on singletons. Principal topics are the kinematical basis for regarding singletons as the constituents of massless particles, and the effect of (negative) curvature in the infrared domain. Ideas that lead to an alternative to Big Bang cosmology are merely sketched. The second half presents new ideas inspired by experimental results on neutrino oscillations. Since leptons are massless before symmetry breaking it is natural to view them as composite states consisting of one Bose singleton (the Rac) and one Fermi singleton (the Di). This gives rise to a particular formulation of the phenomenology of electroweak physics, and strong suggestions for an expansion of the Standard Model. An expansion of the Higgs sector seems inevitable, and flavor changing symmetry, complete with a new set of heavy vector mesons, is a very attractive possibility.     

Optimization of Neutrino Oscillation Parameters Using Differential Evolution

We show how the traditional grid based method for finding neutrino oscillation parameters m2 and tan 2θ can be combined with an optimization technique,Differential Evolution(DE),to get a significant decrease in computer processing time required to obtain minimal chi-square(χ2) in four different regions of the parameter space.We demonstrate efficiency for the two-neutrinos case.For this,the χ2 function for neutrino oscillations is evaluated for grids with different density of points in standard allowed regions of the parameter space of m2 and tan 2θ using experimental and theoretical total event rates of chlorine(Homestake),Gallex+GNO,SAGE,Superkamiokande,and SNO detectors.We find that using DE in combination with the grid based method with small density of points can produce the results comparable with the one obtained using high density grid,in much lesser computation time.     

Neutrino Oscillations in Exotic Geometries and the Equivalence Principle Violation

Taking into account the violation of the equivalence principle, we analyze the propagation of neutrinos in the gravitational field generated by wormholes. The analysis is performed for massive and massless neutrinos. By using the constraints on the (negative) mass of wormholes, which is of the order of stellar-substellar masses, we determine constraints on f which characterizes the degree of violation of the equivalence principle.     

Neutrinos and the Weak Interactions

We show that neutrinos and electrons share the same theoretical structure and satisfy parallel relations particularly of the Large Number kind. We then argue that the neutrino can be described as a “cold” electron in a sense that is detailed, and thereby the weak interactions are indeed a weak form of electromagnetism.     

Search for Cold Dark Matter and Solar Neutrinos with GENIUS and GENIUS-TF

The new project GENIUS will cover a wide range of the parameter space of predictions of SUSY for neutralinos as cold dark matter. Further it has the potential to be a real-time detector for low-energy (pp and ⁷Be) solar neutrinos. A GENIUS Test Facility has been funded and will come into operation by early 2003.     

Potential of octant degeneracy resolution in JUNO

This work extends the idea of using a cyclotron-based antineutrino source for purposes of neutrino physics.Long baseline experiments suffer from degeneracies and correlations between Θ_(23), δ_(CP) and the mass hierarchy.However, the combination of a superconducting cyclotron and a big liquid scintillator detector like JUNO in a medium baseline experiment, which does not depend on the mass hierarchy, may allow to determine whether the position of the mixing angle Θ_(23) is in the lower octant or the upper octant. Such an experiment would improve the precision of the Θ_(23) measurement to a degree which depends on the CP-phase.     

Matter Effects on Neutrino Oscillations in Different Supernova Models

In recent years,with the development of simulations about supernova explosion,we have a better understanding about the density profiles and the shock waves in supernovae than before.There might be a reverse shock wave,another sudden change of density except the forward shock wave,or even no shock wave,emerging in the supernova.Instead of using the expression of the crossing probability at the high resonance,PH,we have studied the matter effects on neutrino oscillations in different supernova models.In detail,we have calculated the survival probability of νe(P_s)and the conversion probability of ν_x(P_c) in the Schrodinger equation within a simplified two-flavor framework for a certain case,in which the neutrino transfers through the supernova matter from an initial flavor eigenstate located at the core of the supernova.Our calculations was based on the data of density in three different supernova models obtained from simulations.In our work,we do not steepen the density gradient around the border of the shock wave,which differs to what was done in most of the other simulations.It is found that the mass and the density distribution of the supernova do make a difference on the behavior of P_s and P_c.With the results of P_s and P_c,we can estimate the number of νe(and ν_x) remained in the beam after they go through the matter in the supernova.     

Domain of mixing angles in three flavor neutrino oscillations

We clarify the domain needed for the mixing angles in three flavor neutrino oscillations. By comparing the ranges of the transition probabilities as functions of the domains of the mixing angles, we show that it is necessary and sufficient to let all mixing angles be in . This holds irrespectively of any assumptions on the neutrino mass squared differences.