Heavy sterile neutrinos: bounds from big-bang nucleosynthesis and SN 1987A

Dolgov, A. D.; Hansen, Steen H.; Raffelt, Georg G.; Semikoz, D.

doi:10.1016/s0550-3213(00)00566-6

Cited by 180 publications

(280 citation statements)

References 24 publications

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“…[6]. For the mass range m ν 4 m π the shape of the NOMAD limit curve is explained by the contribution from the ν 4 → ν τ π 0 decay to the ν 4 decay rate: as the ν 4 → ν τ π 0 decay channel opens up, the branching ratio BR(ν 4 → ν τ e + e − ) drops rapidly as m ν 4 increases.…”

Section: Results and Calculation Of Limitsmentioning

confidence: 92%

“…Concerning the mixing strength |U τ 4 | 2 for the MeV mass region studied in this experiment a limit can be derived from some earlier papers [4], see also [5]. Note that stringent limits on |U τ 4 | 2 in this mass range have been recently obtained from cosmological and astrophysical considerations [6]. For masses in the 3 GeV to ≃ 200 GeV range the LEP experiments have set limits on |U τ 4 | 2 varying from 10 −5 to 10 −1 depending on the ν 4 mass [7].…”

Section: Introductionmentioning

confidence: 83%

“…A similar method allowing a more accurate evaluation of the e + e − efficiency correction factor at higher energies is based on the inclusive e + e − /γ double ratio RR defined again as RR = R Data /R M C with 6) where N γ γ , N γ e + e − are the numbers of single isolated photons and e + e − pairs in the same data sample of ν µ CC events used for the collinearity check.…”

Section: Data Analysis and Selection Criteriamentioning

confidence: 99%

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Search for heavy neutrinos mixing with tau neutrinos

et al. 2001

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We report on a search for heavy neutrinos (ν 4 ) produced in the decay D s → τ ν 4 at the SPS proton target followed by the decay ν 4 → ν τ e + e − in the NOMAD detector. Both decays are expected to occur if ν 4 is a component of ν τ . From the analysis of the data collected during the 1996-1998 runs with 4.1 × 10 19 protons on target, a single candidate event consistent with background expectations was found. This allows to derive an upper limit on the mixing strength between the heavy neutrino and the tau neutrino in the ν 4 mass range from 10 to 190 MeV. Windows between the SN1987a and Big Bang Nucleosynthesis lower limits and our result are still open for future experimental searches. The results obtained are used to constrain an interpretation of the time anomaly observed in the KARMEN1 detector.Key words: neutrino mixing, neutrino decay IntroductionIn the Standard Model all fundamental fermions have a right-handed component that transforms as an isosinglet under the SU(2) L gauge group except neutrinos, which are observed only in left-handed form. However, heavy neutrinos which are decoupled from W and Z bosons and hence are mostly isosinglet (sterile) arise in many models that attempt to unify the presently known interactions into a single gauge scheme, such as Grand Unified Theories or Superstrings inspired models [1]. They are also predicted in models trying to solve the problem of baryo-or leptogenesis in the Universe, in many extended electroweak models, such as left-right symmetric and see-saw models [1]. Their masses are predicted to be within the GeV − TeV range. The existence of a light ( eV or ≪ eV) sterile neutrino is expected in schemes that attempt to solve the presently observed indication from atmospheric, solar and LSND experiments that neutrinos are massive, see e.g. [2] and references therein. More generally one can also look for an isosinglet neutrino with intermediate mass such as in the keV − MeV range. For instance, such neutrinos with masses in the range 1 -40 keV were recently considered as a candidate for warm dark matter [3].If heavy neutrinos exist, many crucial questions arise. For example, for massive neutrinos the flavour eigenstates (ν e , ν µ , ν τ , ...) need not coincide with the mass eigenstates (ν 1 , ν 2 , ν 3 , ν 4 ...), but would, in general, be related through a unitary transformation. Such a generalised mixing:could result in neutrino oscillations when the mass differences are small, and in decays of heavy neutrinos when the mass differences are large. The motivation and purpose of this work is to search for a neutral heavy lepton ν 4 which is dominantly associated with the third generation of light neutrinos, ν τ , via the mixing term |U τ 4 | 2 . If such a particle exists it might be produced in the decay D s → τ ν 4 at the SPS proton target followed by the decay ν 4 → ν τ e + e − in the NOMAD detector as is illustrated in Figure 1 (see also Section 3). The experimental signature of these events is clean and they can be selected with small background due t...

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Section: Results and Calculation Of Limitsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 83%

Section: Data Analysis and Selection Criteriamentioning

confidence: 99%

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Search for heavy neutrinos mixing with tau neutrinos

et al. 2001

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“…By regarding all decay branches possible through oscillations, the mean lifetime of a sterile Dirac neutrino of mass, m s , has been determined to be [35,36] …”

Section: Constraining Mass and Mixing Anglementioning

confidence: 99%

Probing the nature of dark matter with cosmic x rays: Constraints from “dark blobs” and grating spectra of galaxy clusters

et al. 2007

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Gravitational lensing observations of galaxy clusters have identified dark matter blobs with remarkably low baryonic content. We use such a blob to probe the particle nature of dark matter with x-ray observations. From these observations we improve the most conservative constraints from the Milky Way halo on a particular dark matter candidate, the sterile neutrino, by an order of magnitude. We also study high resolution x-ray grating spectra of a cluster of galaxies. Based on these conservative constraints obtained from cosmic x-ray observations alone, the low mass (m s & 10 keV) and low mixing angle (sin 2 2 & 10 ÿ6 ) sterile neutrino is still a viable dark matter candidate.

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“…(see, for instance, Refs. [11,12,13] and references therein). This implies certain constrains on the neutrino masses and mixing, which, however, for unstable neutrinos, such as ν h studied in the present paper, are quite weak and involve various uncertainties.…”

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confidence: 99%

Sterile neutrinos in neutrinoless double beta decay

et al. 2005

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We study possible contribution of the Majorana neutrino mass eigenstate ν h dominated by a sterile neutrino component to neutrinoless double beta (0νββ) decay. From the current experimental lower bound on the 0νββ-decay half-life of 76 Ge we derive stringent constraints on the ν h − ν e mixing in a wide region of the values of ν h mass. We discuss cosmological and astrophysical status of ν h in this mass region.

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Heavy sterile neutrinos: bounds from big-bang nucleosynthesis and SN 1987A

Abstract: Cosmological and astrophysical effects of heavy (10-200 MeV) sterile Dirac neutrinos, mixed with the active ones, are considered. The bounds on mass and mixing angle from both supernovae and big-bang nucleosynthesis are presented.

Cited by 180 publications

References 24 publications

Search for heavy neutrinos mixing with tau neutrinos

Search for heavy neutrinos mixing with tau neutrinos

Probing the nature of dark matter with cosmic x rays: Constraints from “dark blobs” and grating spectra of galaxy clusters

Sterile neutrinos in neutrinoless double beta decay

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