Neutrino oscillation interference phase in Kerr space--time

The mass neutrino interference phases along the null trajectory and the geodesic line in Kerr space--time are studied on the plane θ=π/2. Because of the rotation object in Kerr space--time, a particle travelling along the radial geodesic must have a dragging effect produced by the angular momentum of the central object. We give the correction of the phase due to the rotation of the space--time. We find that the type-I interference phase along the geodesic remains the double of that along the null on the condition that the rotating quantity parameter a² is preserved and the higher order terms are negligible (e.g. a⁴). In addition, we calculate the proper oscillation length in Kerr space--time. All of our results can return to those in Schwarzschild space--time as the rotating parameter a approaches zero.     

Neutrino

Neutrinos are the only fundamental fermions which have no electric charges. Because of that neutrinos have no direct electromagnetic interaction and at relatively small energies they can take part only in weak processes with virtual W ^± and Z ⁰ bosons. Neutrino masses are many orders of magnitude smaller than masses of charged leptons and quarks. These two circumstances make neutrinos unique, special particles. The history of the neutrino is very interesting, exciting and instructive. We try here to follow the main stages of the neutrino history starting from the famous Pauli letter and finishing with the discovery and study of neutrino oscillations. Outstanding contribution to the neutrino physics of Bruno Pontecorvo is discussed in some details.     

Neutrino masses

A status report about experimental searches for neutrino masses is given. Direct mass experiments for the three different neutrino flavours are discussed. Under the assumption of neutrino mixing results of experiments looking for neutrino decay and distortions in spectra of weak decays are reported.     

Neutrino unification

Present neutrino data are consistent with neutrino masses arising from a common seed at some "neutrino unification" scale M(X). Such a simple theoretical ansatz naturally leads to quasidegenerate neutrinos that could lie in the electron-volt range with neutrino mass splittings induced by renormalization effects associated with supersymmetric thresholds. In such a scheme the leptonic analog of the Cabibbo angle straight theta(middle dot in circle) describing solar neutrino oscillations is nearly maximal. Its exact value is correlated with the smallness of straight theta(reactor). The two leading mass-eigenstate neutrinos present in nu(e) form a pseudo-Dirac neutrino, avoiding conflict with neutrinoless double beta decay.     

Neutrino mass and unification

I discuss the implications of the observed masses and mixings of neutrinos for unification beyond the standard model and point out the important role that ongoing searches for the remaining mixing angle θ₁₃, neutrinoless double beta decay as well as possible searches for a Z^′ at LHC can play in this discussion.     

Neutrino cosmology

Cosmological data are reviewed questioning whether the universe may be open and dominated by neutrinos and gravitons rather than by baryons. The thermal history of the Lepton Era is investigated incorporating the effects of neutral currents, additional neutrinos, and a small neutrino mass. In the canonical version of Big Bang cosmology (equal numbers of neutrinos and antineutrinos), the neutrino number and energy density is, like that of photons, gravitationally insignificant unless the neutrino has a small mass (10 eV). The neutrino sea can be cosmologically significant if it is degenerate (so that the net leptonic or muonic charge is nonzero) with7×10 ⁵ neutrinos (or antineutrinos) per cm.³ This density homogeneously spread out is still so low that even the most energetic cosmic ray protons will not be stopped, even if neutral currents exist with the usual weak strength. If these degenerate neutrinos have a small mass (0.5 eV), they will condense into degenerate neutrino superstars of the size and mass of galactic clusters. If neutral currents make the (ev) (ev) coupling five times greater than what it is in V — A theory, nucleosynthesis commences a little earlier than conventionally assumed. This increases the cosmological He⁴ abundance predicted only slightly from Y= 0.27 to Y= 0.29. An appendix reviews the effect of neutral currents on neutrino processes in stars.Supported in part by the U.S.A.E.C.     

Neutrino cosmology

We present a class of non-stationary cosmological solutions of coupled Einstein-Dirac equations which correspond to an Universe filled solely with neutrinos of right and/or left helicity.     

Neutrino superfluidity

It is shown that Dirac-type neutrinos display BCS superfluidity for any nonzero mass. The Cooper pairs are formed by attractive scalar Higgs boson exchange between left- and right-handed neutrinos; in the standard SU(2) x U(1) theory, right-handed neutrinos do not couple to any other boson. The value of the gap, the critical temperature, and the Pippard coherence length are calculated for arbitrary values of the neutrino mass and chemical potential. Although such a superfluid could conceivably exist, detecting it would be a major challenge.     

Neutrino Lensing

Due to the intrinsic properties of neutrinos, the gravitational lens effect for a neutrino should be more colorful and meaningful than the normal lens effect of a photon. Other than the experiments operated at terrestrial laboratory, in principle, we can propose a completely new astrophysical method to determine not only the nature of the gravity of lens objects but also the mixing parameters of neutrinos by analyzing neutrino trajectories near the central objects. However, the angular, energy and time resolution of the neutrino telescopes are still comparatively poor, so we just concentrate on the two classical tests of general relativity, i.e. the angular deflection and the time delay of the neutrino by a lens object as a preparative work in this paper. In addition, some simple properties of neutrino lensing are investigated.     

Neutrino Mass Hierarchy and CP Violation in Long Baseline Neutrino Experiment

We discuss the CP violation in long base line neutrino oscillation experiments. The direct measurement of CP violation is the difference of transitions probability between CP conjugate channels. The sign of Δ ₃₁ is not yet determined, we assume two mass hierarchy conditions, normal (Δ ₃₁>0) and inverted (Δ ₃₁<0). In this paper, we study the CP violation and neutrino mass hierarchy effect in vacuum and matter for long baseline BNL experiments. By an appropriate chose of experimental parameter, neutrino energy and traveled distance. We find that, in matter normal mass hierarchy en-chanced maximum CP violation over their invert mass hierarchy value by 12 %.     

Detecting the Neutrino

In 1930 Wolfgang Pauli suggested that a new particle might be required to make sense of the radioactive-disintegration mode known as beta decay. This conjecture initially seemed impossible to verify since the new particle, which became known as the neutrino, was uncharged, had zero or small mass, and interacted only insignificantly with other matter. In 1951 Frederick Reines and Clyde L. Cowan, Jr., of the Los Alamos Scientific Laboratory undertook the difficult task of detecting the free neutrino by observing its inverse beta-decay interaction with matter. They succeeded in 1956. The neutrino was accepted rapidly as a fundamental particle despite discrepancies in reported details of the experiments and despite the absence of independent verification of the result. This paper describes the experiments, examines the nature of the discrepancies, and discusses the circumstances of the acceptance of the neutrino's detection by the physics community.