Neutrino Oscillations In Matter Research Articles

Parametric resonance in neutrino oscillations in matter

Neutrino oscillations in matter can exhibit a specific resonance enhancement — parametric resonance, which is different from the MSW resonance. Oscillations of atmospheric and solar neutrinos inside the earth can undergo parametric enhancement when neutrino trajectories cross the core of the earth. In this paper we review the parametric resonance of neutrino oscillations in matter. In particular, physical interpretation of the effect and the prospects of its experimental observation in oscillations of solar and atmospheric neutrinos in the earth are discussed.

On Resonances and Mixing Angles in Three Neutrino Oscillations in Matter

We find exact analytical expressions for mixing angles in matter in the context of three generation neutrino oscillations in matter to discuss the role of resonances in this phenomenon. We show that some knowledge from conventional two neutrino MSW effect, which has been extended to approximated solutions to three neutrino oscillations, has to be abandoned in this exact approach. We observe that maximal values for the mixing angles in matter are found in nonresonant regions and stationary phases do not coincide anymore with resonances in this simple extension of the MSW effect. We present a general way to identify a resonance and discuss what we can physically expect in these regions

Exact analytic description of neutrino oscillations in matter with an exponentially varying density for an arbitrary number of neutrino species.

Exact analytical expressions in terms of generalized confluent hypergeometric functions for the transition amplitudes of neutrino oscillations in presence of matter are computed for an arbitrary number of species. The density of matter is assumed to be exponentially decaying. The results can be used for the description of matter-induced neutrino oscillations in the Sun which can take place when the solar neutrinos propagate radially from the interior to the surface. Expressions are particularly simple in the limit of infinite propagation time as is suitable for the case of detection at Earth. PACS: 14.60.Pq, 02.30.Gp, 02.30.Hq

Neutrino oscillations in matter

Neutron oscillations can be drammatically altered in the presence of matter. This effect can give a natural explanation of the solar neutrino problem. Recent experiments are analyzed in this framework and bounds on neutrino masses and mixing parameters are given.

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.

Survey of atmospheric neutrino data and implications for neutrino mass and mixing

A detailed comparison is made of the atmospheric neutrino results obtained by the Fréjus, IMB-3, and Kamiokande detectors. The implications of these results for vacuum neutrino oscillations are presented, and juxtaposed with the results for matter neutrino oscillations from the solar neutrino data.

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.

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.

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.

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.

Neutrino oscillation in matter induced by charged scalar particles

Neutrino oscillation is induced between νμ and ντ in matter, there exists a charged scalar particle as required to give a conjectured large magnetic moment of neutrinos. Possibilities of the detection of this effect are discussed.

O(5)�U(1) electroweak gauge theory and the neutrino oscillations in matter

A study is made of the groupO(5)×U(1). The group is economical in the number of gauge bosons, which we associate with each of its generators, and is anomaly-free. The left-handed leptonsL ≡(v e ,e,μ,v μ ) L are assigned to the four-dimensional spinorial representations ofO(5). The right-handed particles are taken to be the singlets of the group. The theory has three sets of gauge bosons: (1) analogues of the GWS model, (2) additional charged gauge bosons, and (3) a set of three additional neutral gauge bosons as compared to the GWS model. We introduce neutrino mixing by mixing the additional charged gauge bosons. We develope a theory of neutrino oscillations in matter in such a way that in the absence of matter the scattering length reduces to the usual scattering length in vacuum. Even if the neutrino masses are equal or the neutrinos are massless, we still have neutrino oscillations in matter, a result already noted by Wolfenstein.

On the non-adiabatic neutrino oscillations in matter

Following the approach of Zener, we obtain an exact expression (in terms of Weber-Hermite functions) for the two-neutrino transition (oscillation) probability in matter with linearly varying density. It takes a simple form when the resonance density differs considerably from the initial and final densities. The conditions under which the approximate expression for the probability derived in the latter case can be used for the description of the neutrino transitions in the interior of the Sun are also briefly discussed.

Oscillations of three generations of neutrinos and the solar neutrino problem

The resonant neutrino oscillations in matter are assumed to be responsible for the observed reduction in the capture rate for the 37Cl detector. The expression of the probability that a solar ve reaches the Earth as a ve is given in the case of three generations. In the small mixing angle approximation, we describe all the regions of neutrino parameters which give rise to a capture rate of 2.1 SNU for 37Cl and we give the corresponding prediction for the 71Ga detector.

Resonant amplification of three-neutrino oscillations in matter

We investigate the resonant amplification of the neutrino oscillations in matter in case of three flavour neutrinos. We find simple solutions for the effective mixing angles and mass-squared differences which are true up to terms of higher than the first (nontrivial) order with respect to the vacuum mixing angles. The implifications of these solutions are briefly discussed.

Implications of the mikheyev-smirnov-wolfenstein (MSW) mechanism of amplification of neutrino oscillations in matter

Mikheyev and Smirnov have recently proposed a novel and plausible solution of the solar neutrino problem, based on the resonant amplification of the neutrino oscillations in matter. We comment on several aspects of this mechanism. (i) For the values of neutrino masses and mixing angles predicted by the seesaw model of grand unified theories, the MSW effect may take place naturally in the Sun, leading to a considerable reduction of the flux of solar electron neutrinos, with the dominant transition being v e → v τ (rather than v e → v μ ). (ii) Oscillations between the ordinary neutrinos ( v e, v μ , v τ ) can affect primordial nucleosynthesis, but the effect is small (i.e., the abundance of 4He is predicted to change by less than 1.3 × 10 −3). (iii) A comparison of some of the general properties of neutrino oscillations in matter and in vacuum is given.

Neutrino oscillations in matter

The effect of coherent forward scattering must be taken into account when considering the oscillations of neutrinos traveling through matter. In particular, for the case of massless neutrinos for which vacuum oscillations cannot occur, oscillations can occur in matter if the neutral current has an off-diagonal piece connecting different neutrino types. Applications discussed are solar neutrinos and a proposed experiment involving transmission of neutrinos through 1000 km of rock.