Fate of the sterile neutrino

Barger, V.; Kayser, Boris; Learned, J. G.; Weiler, Thomas J.; Whisnant, K.

doi:10.1016/s0370-2693(00)00950-3

Cited by 92 publications

(101 citation statements)

References 47 publications

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“…The new analysis of the experimental data results in a shift of the allowed region towards smaller values of the mixing angle, sin 2 (2θ LSN D ), reconciling the 3+1 scheme with exclusion bounds coming from CDHS [21], CCFR [22] and Bugey [23]. Although the 2+2 scheme is still favoured 3 , the 3+1 scheme is at present marginally compatible with the data, [25,26,27,28]. However, the 2+2 and the 3+1 scheme face the upcoming experiments on totally different footing: if MiniBooNE disconfirms LSND, the 2+2 scheme is falsified.…”

Section: Introductionmentioning

confidence: 67%

The 2+2 and 3+1 four-family neutrino mixing at the neutrino factory

Donini

Meloni

2001

Eur. Phys. J. C

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We upgrade the study of the physical reach of a Neutrino Factory in the Four Family Neutrino Mixing scenario taking into account the latest LSND results that points out how the 3+1 scheme cannot be completely ruled out within the present experimental data (although the 2+2 scheme is still the preferred choice when four neutrinos are considered). A detailed comparison of the physical reach of the ν-factory in the two schemes is given, with similar results for the sensitivity to the mixing angles. Huge CP-violating effects can be observed in both schemes with a near, O(10) Km, detector of O(10) Kton size in the ν µ → ν τ channel. A smaller detector of 1 Kton size can still observe very large effects in this channel.

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Section: Introductionmentioning

confidence: 67%

The 2+2 and 3+1 four-family neutrino mixing at the neutrino factory

Donini

Meloni

2001

Eur. Phys. J. C

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“…In this case νa is a linear combination of νµ and ντ . Furthermore, the treatment is also valid in 3+1 four-neutrino mixing schemes in which the sterile neutrino is practically decoupled from the active ones (1 − |Us4| 2 ≪ 1) [34] and Ue3 is small, as indicated by CHOOZ data [22]. Table 1:…”

Section: Results In Frequentistmentioning

confidence: 99%

Bayesian view of solar neutrino oscillations

Garzelli

Giunti

2001

J. High Energy Phys.

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We present the results of a Bayesian analysis of solar neutrino data in terms of ν e → ν µ,τ and ν e → ν s oscillations, where ν s is a sterile neutrino. We perform a Rates Analysis of the rates of solar neutrino experiments, including the first SNO CC result, and spectral data of the CHOOZ experiment, and a Global Analysis that takes into account also the Super-Kamiokande day and night electron energy spectra. We show that the Bayesian analysis of solar neutrino data does not suffer any problem from the inclusion of the numerous bins of the CHOOZ and Super-Kamiokande electron energy spectra and allows to reach the same conclusions on the favored type of neutrino transitions and on the determination of the most favored values of the oscillation parameters in both the Rates and Global Analysis. Our Bayesian analysis shows that ν e → ν s transitions are strongly disfavored with respect to ν e → ν µ,τ transitions. In the case of ν e → ν µ,τ oscillations, the Large Mixing Angle region is favored by the data (86% probability), the LOW region has some small chance (13% probability), the Vacuum Oscillation region is almost excluded (1% probability) and the Small Mixing Angle region is practically excluded (0.01% probability). We calculate also the marginal posterior probability distributions for tan 2 ϑ and ∆m 2 in the case of ν e → ν µ,τ oscillations and we show that the data imply large mixing almost with certainty and large values of ∆m 2 are favored (2 × 10 −6 eV 2 < ∆m 2 < 10 −3 eV 2 with 86% probability). We present also the results of a standard least-squares analysis of solar neutrino data and we show that the standard goodness of fit test is not able to reject pure ν e → ν s transitions. The likelihood ratio test, which is insensitive to the number of bins of the CHOOZ and Super-Kamiokande energy spectra, allows to reject pure ν e → ν s transitions in favor of ν e → ν µ,τ transitions only in the Global Analysis.

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“…The standard arguments disfavoring 3+1 spectra (triplet+singlet) with respect to 2+2 spectra (two doublets) in the interpretation of the current 4ν oscillation phenomenology [1] appear to be somewhat weakened [12,19] in light of the most recent LSND data [6], and should be perhaps revisited quantitatively. Here we make just a few qualitative comments on the mixing pattern that is likely to emerge in 3+1 models characterized by a triplet (ν 1 , ν 2 , ν 3 ) (mainly responsible for solar and atmospheric oscillations) and by a "loner" state ν 4 (mainly responsible for LSND oscillations).…”

Section: Remarks On 3+1 Mass Spectramentioning

confidence: 99%

“…or a linear combination of ν e and ν s (presumably disfavored). Therefore, the favored option for 3+1 spectra seems to imply ν 4 ∼ ν s , with (at least) a small subdominant component of ν µ and ν e in ν 4 , necessary to drive LSND oscillations (see also [12,39]). 3 Assuming ν 4 ∼ ν s in 3+1 models, the triplet states (ν 1 , ν 2 , ν 3 ) would then approximately be linear combinations of (ν e , ν µ , ν τ ), and the triplet phenomenology of solar and atmospheric neutrinos would practically become equivalent to that of a standard framework with three active neutrinos.…”

Section: Remarks On 3+1 Mass Spectramentioning

confidence: 99%

“…[10]). However, it seems premature to rule out the sterile neutrino hypothesis on the basis of the present information only [11,12]: on the one hand, past experience on global data fits has shown that, sometimes, hypotheses rejected (accepted) at 95% or 99% C.L. can surprisingly revive (die); on the other hand, the underlying 4ν oscillation pattern might be more complicated [3,13,14] than assumed in Eqs.…”

Section: Introductionmentioning

confidence: 99%

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Four-neutrino oscillation solutions of the atmospheric neutrino anomaly

2001

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In the context of neutrino scenarios characterized by four (three active plus one sterile) neutrino species and by mass spectra with two separated doublets, we analyze solutions to the atmospheric neutrino anomaly which smoothly interpolate between ν µ → ν τ and ν µ → ν s oscillations. We show that, although the Super-Kamiokande data disfavor the pure ν µ → ν s channel, they do not exclude its occurrence, with sizable amplitude, in addition to the ν µ → ν τ channel. High energy muon data appear to be crucial in assessing the relative amplitude of active and sterile neutrino oscillations. It is also qualitatively shown that such atmospheric ν solutions are compatible with analogous solutions to the solar neutrino problem, which involve oscillations of ν e in both sterile and active states. PACS: 14.60. Pq, 13.15.+g, 95.85.Ry

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Fate of the sterile neutrino

Cited by 92 publications

References 47 publications

The 2+2 and 3+1 four-family neutrino mixing at the neutrino factory

The 2+2 and 3+1 four-family neutrino mixing at the neutrino factory

Bayesian view of solar neutrino oscillations

Four-neutrino oscillation solutions of the atmospheric neutrino anomaly

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