Matter Oscillations Research Articles

Oscillations of non-relativistic neutrinos

Abstract Neutrino oscillations are studied by describing the propagation of neutrinos as superpositions of mass-eigenstate wave packets, without making the usual relativistic assumption. This treatment leads to several interesting effects in the neutrino oscillation. The coherence length beyond which neutrinos cease to oscillate and its effects on the oscillations are derived and discussed. To elucidate the physics involved, a pictorial description of neutrino oscillations is presented with use of the density matrix formulation. The results are generalized to the case of neutrino oscillations in matter. The effect of the coherence length in the MSW effect is also pictorially explained. It is shown that if the coherence length becomes shorter than the size of the resonance region, non-abiabatic MSW transitions become increasingly more abiabatic, making the neutrino conversion more efficient.

Mixed first and second class neutrino oscillations

We argue that the general form of the neutrino mass matrix implies that second-class (active→sterile) oscillations require serious consideration. A combination of such oscillations in both vacuum and matter is discussed. For the latter scenario we derive the general mass matrix for three light Majorana neutrinos, one of which is sterile. Implications for solar neutrino observations by neutral-current detectors, such as the Sudbury Neutrino Observatory, are discussed.

Magnus approximation for nonadiabatic transitions and neutrino oscillations in matter.

The Magnus expansion of the time-displacement operator is used to calculate nonadiabatic level crossing induced by a time-dependent Hamiltonian. We consider Hamiltonians that can be represented as a Hermitian 2\ifmmode\times\else\texttimes\fi{}2 matrix. As an interesting nontrivial application an analytic expression for the flavor survival probability is derived for neutrinos which propagate through a matter-enhanced oscillation region.

Coherence of neutrino oscillations in vacuum and matter in the wave packet treatment

We present a geometrical representation of neutrino oscillations in vacuum and matter in which a propagating neutrino is described by a superposition of mass-eigenstate wave packets (energy-eigenstate wave packets in matter). The effect of the coherence length (that is the distance beyond which the wave packets separate) in the MSW effect is illustrated by using the solar neutrinos as an example. It is shown that, if the coherence length is shorter than the size of the resonance region, non-adiabatic MSW transitions become increasingly adiabatic as the coherence length is decreased.

Neutrino tomography of the Earth

Neutrino oscillations inside matter are very sensitive to the density of the medium traversed by the neutrinos. If the neutrino mixing angle (so far unknown) is not very small, then the neutrino oscillation length is of the size of the Earth, and we can use the phenomenon of neutrino matter oscillations to study the Earth's density distribution. Although neutrino attenuation data have already been proposed as a means to infer the density structure of the Earth, we show that neutrino oscillation data could also be used to make a density tomograph of the Earth. A numerical experiment in which neutrino beams from an accelerator are sent across the Earth, and are detected at six different locations on the Earth's surface, shows the feasibility of using neutrino oscillation data, with the advantage of using only currently available neutrino energies.

ON T-VIOLATION IN MATTER NEUTRINO OSCILLATIONS

We continue the investigation of possible T-violating effects in three-neutrino oscillations in matter. Intriguingly simple analytical expression for the experimentally measurable quantity [Formula: see text] (t) is derived.

Neutrino oscillations in inhomogeneous matter.

An equation is derived for the evolution of the density matrix for neutrinos propagating, and mixing, in inhomogeneous matter. A measure of the decrease in the efficiency of the Mikheyev-Smirnov-Wolfenstein (MSW) transformation of ${\ensuremath{\nu}}_{e}$ to ${\ensuremath{\nu}}_{x}$ is defined, and is proved to increase steadily as the neutrino traverses a lumpy medium. It is estimated that, at the least, 1% density variations in the solar core on a scale of 1000 km would be required in order to disrupt the MSW predictions for the solar-neutrino problem. In the case of the supernova core, 0.01% variations on the scale of the c.m. system would be sufficient to alter drastically the results of scenarios which have been proposed.

Magnus expansion and the two-neutrino oscillations in matter.

We show that the Magnus expansion can help to deal with the problem of matter-neutrino oscillations in the nonadiabatic regime of the two-neutrino-flavor case. An analytic result for the electron-neutrino survival probability is derived in a quite simple way without reference to any particular electron density.

WKB calculation of neutrino matter oscillations

The WKB method is used to obtain the neutrino transition (oscillation) amplitude in matter. The first two terms in our expansion correspond to neutrino adiabatic propagation, while the third term contains nonadiabatic corrections. As an application we consider the case of linear matter density and we compare the results with the available exact solution.

Coherence condition for resonant neutrino oscillation.

which holds the key for matter oscillation has not been mentioned in relation to the MSW effect until now. We study the coherence condition for a neutrino to keep coherence between the effective mass eigenstates in the presence of matter and, according to this condition, investigate whether or not the MSW effect happens in the cases of solar and supernova neutrinos. If the propagating neutrino loses the coherence between its effective mass eigenstates before arriving at the resonant density region, the resonant amplification of neutrino oscillations will no longer occur. That is, the MSW mechanism can not work in that case. Besides the resonance and adiabatic conditions 2 , there is, for the occurrence of RNO, an important condition which originated in the existence of a coherent wave length. 2. Coherence Condition According to the studies about the width of spectral lines, the emitted Ve really has a wave packet of width d along the propagating directions. Within a very dense and hot medium, d is limited by collisions between the Ve emitter and neighboring particles because of the random-phase change of Ve wave trains emitted before and after collision. Such an effect is called collision (or pressure) broadening. Using the coherence time To which is the effective time to emit an uninterrupted train of

Nötzold solution of matter oscillation of solar neutrinos.

An exact analytic solution of the matter oscillation of neutrinos proposed by N\"otzold for a hyperbolic-tangent distribution of electron density, which is more realistic for the case of the Sun than other distributions, is improved by an exact treatment of the initial condition at any production point of the neutrino, where it is not on a flat place of r=-\ensuremath{\infty} as N\"otzold took. It must be stressed that the tanh fit can be made precisely even for the central region of the Sun, as well as the exponential tail in the outer region. I then give a compact analytic formula with elementary functions, which is a good approximation to the ``exact'' solution.

Neutrino oscillations in matter

Nonzero neutrino masses would provide new, unique information on particle physics beyond the standard model. Neutrino flavor oscillations provide the most sensitive method for directly testing for small neutrino masses. When the oscillations occur in matter, a resonance can occur that dramatically enhances the flavor mixing and can lead to conversion from one neutrino flavor to another. This is an attractive solution to the long-standing "solar neutrino problem." The phenomenon of neutrino oscillations in matter is reviewed. Analytic descriptions of the neutrino flavor survival probability in matter are considered in detail. A discussion is given for applications of neutrino oscillations in matter for the sun, Earth, supernovae, and the early universe.

Analytic treatment of high-order adiabatic approximations of two-neutrino oscillations in matter.

In this paper the high-order adiabatic approximation method proposed by the author is used to approach the nonadiabatic effects of two-neutrino oscillations in matter. We not only obtain the analytic expressions for high-order approximate solutions of the neutrino-oscillations equation but also give nonadiabatic corrections to the probability of the adiabatic transition between two neutrinos in matter with arbitrarily varying density.

On the oscillations of solar neutrinos in the sun

Using the exact solution of the system of evolution equations describing two-neutrino oscillations in matter with exponentially varying density we derive simple analytic expressions for the oscillating terms in the probability of solar neutrino survival in the sun. The regionsof values of the parameters, characterizing the two-neutrino oscillations terms can be non-neglegible are determined.

An analytic description of three-neutrino oscillations in matter with varying density

We derive analytic expressions for the amplitudes of the three-neutrino transitions in matter with varying density in terms of two-neutrino transition amplitudes. The conditions under which these expressions are valid are discussed in detail. The results obtained are used to describe analytically the transitions of solar neutrinos in the interior of the Sun when the three flavour neutrinos ϱ e, ϱ μ and ϱ τ can take part in oscillations in vacuum.

Acoustic properties of neutron stars

view Abstract Citations (75) References (46) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Acoustic Properties of Neutron Stars Epstein, Richard I. Abstract Neutron and proton superfluidity alters sound wave propagation in the interior of a neutron star. The partial decoupling of the motions of different components of the matter creates new modes and modifies the previously known modes. This paper presents the sound velocities and the relative displacements of the different components for short-wavelength longitudinal and transverse oscillations in neutron star matter. The new compressional and shear modes that a neutron star can support are discussed. Publication: The Astrophysical Journal Pub Date: October 1988 DOI: 10.1086/166797 Bibcode: 1988ApJ...333..880E Keywords: Acoustic Properties; Neutron Stars; Stellar Structure; Wave Propagation; Acoustic Velocity; Propagation Modes; Stellar Cores; Superfluidity; Velocity Distribution; Astrophysics; DENSE MATTER; STARS: NEUTRON; WAVE MOTIONS full text sources ADS |

Anomalous propagation of neutrino beams through dense media.

The phenomenon of fermion oscillations in matter is examined using the Dirac equation. The resonant oscillation observed by Mikheyev, Smirnov, Wolfenstein, and Bethe for solar neutrinos is reinterpreted as birefringence for a family of fermion waves. Particular attention is given to the presence of negative-energy states in the medium, and the resultant redefinition of the ground state. Such a redefinition is not expected to affect significantly the solution to the solar-neutrino puzzle posed by a resonant oscillation frequency within the solar core, but can alter the propagation of fermions through ultradense media.

Neutrino oscillations in matter and measurement of the ν luminosity of the sun in the past

The suppression factors for the ν capture rate in 205Tl due to neutrino oscillations in matter have been calculated. The possibility of measuring the ν luminosity in the past is discussed.

Stability of plasma oscillations in hot gluonic matter.

It is argued that the high-temperature gluon-plasma damping constants previously calculated by use of the background-field method and the Vilkovisky-DeWitt effective action do not have a physical interpretation since they are not derived from correlation functions relevant to linear-response theory. A correct application of the gauge- and parametrization-independent formalism does not affect the plasmon frequency, but yields the following modified results for the longitudinal and transverse damping constants: ..gamma../sub L/ = ..gamma../sub T/ = -(9/32..pi..)g/sup 2/NT. .AE

Matter oscillations: Neutrino transformation in the Sun and regeneration in the Earth.

Calculations of neutrino regeneration phenomena in the Earth as well as transformation in the Sun are presented with relevant predictions for several existing and planned neutrino detection experiments. The validity of computational approximations in the solar case is appropriately investigated. Sensitivity of the calculated results to the solar model is noted. Transformation and regeneration phenomena are calculated to result from transmission through the Earth of neutrinos with E(MeV)/..delta..m/sup 2/(eV/sup 2/) in the vicinity of 10/sup 6/ to 10/sup 7/. As a result, large time-of-night and seasonal variations are predicted for various solar-neutrino experiments in this parameter range. Analogous effects are predicted for terrestrial cosmic-ray and accelerator experiments.