Anomaly in the time distribution of neutrinos from a pulsed beam stop source

Armbruster, B.; Blair, I.M.; Bodmann, B.; Booth, N. E.; Drexlin, G.; Eberhard, V.; Edgington, J.A.; Eitel, K.; Finckh, E.; Gemmeke, H.; Hößl, J.; Jannakos, T.; Kleifges, M.; Kleinfeller, J.; Kretschmer, W.; Maschuw, R.; Plischke, P.; Rapp, J.; Seligmann, B.; Stumm, O.; Wolf, J.; Zeitnitz, B.

doi:10.1016/0370-2693(95)00258-m

Cited by 61 publications

(58 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is similar in outlook to Ref. [8] where, in light of the Karmen time anomaly [24], the impact on SN1987A of a neutralino with the specific mass (Mχ = 34 MeV) was examined. We extend this work to a general neutralino.…”

Section: = 10supporting

confidence: 67%

Supernovas and light neutralinos: SN 1987A bounds on supersymmetry reexamined

et al. 2003

View full text Add to dashboard Cite

For non-universal gaugino masses, collider experiments do not provide any lower bound on the mass of the lightest neutralino. We review the supersymmetric parameter space which leads to light neutralinos, Mχ < ∼ O(1 GeV), and find that such neutralinos are almost pure bino. In light of this, we examine the neutralino lower mass bound obtained from supernova 1987A (SN1987A). We consider the production of binos in both electron-positron annihilation and nucleon-nucleon binostrahlung. For electron-positron annihilation, we take into account the radial and temporal dependence of the temperature and degeneracy of the supernova core. We also separately consider the Raffelt criterion and show that the two lead to consistent results. For the case of bino production in N N collisions, we use the Raffelt criterion and incorporate recent advances in the understanding of the strong-interaction part of the calculation in order to estimate the impact of bino radiation on the SN1987A neutrino signal. Considering these two bino production channels allows us to determine separate and combined limits on the neutralino mass as a function of the selectron and squark masses. For Mχ ∼ 100 MeV values of the selectron mass between 300 and 900 GeV are inconsistent with the supernova neutrino signal. On the other hand, in contrast to previous works, we find that SN1987A provides almost no bound on the squark masses: only a small window of values around 300 GeV can be excluded, and even then this window closes once Mχ > ∼ 20 MeV.

show abstract

Section: = 10supporting

confidence: 67%

Supernovas and light neutralinos: SN 1987A bounds on supersymmetry reexamined

et al. 2003

View full text Add to dashboard Cite

show abstract

“…[25] constrain the ν 4 lifetime to be less than 0.1 sec. 2 Using the KARMEN signal curve [23] results in a small window around BR(π + → µ + + X) ≃ 10 −12 between our result [16] and BBN one left untested. Note that the recent PSI result on a search for the 33.9 MeV particle in π + → µ + + X decay corresponds to BR(π + → µ + + X) < 6.0 · 10 −10 at 95% CL [27].…”

Section: The Karmen Time Anomalymentioning

confidence: 64%

“…Our data can also be used to restrict one of the interpretations of the time anomaly observed by the KARMEN experiment [23]. The anomaly is a bump in the time distribution of ν e and ν µ induced events which was expected to be well described by the single exponential from muon decays.…”

Section: The Karmen Time Anomalymentioning

confidence: 94%

“…The anomaly is a bump in the time distribution of ν e and ν µ induced events which was expected to be well described by the single exponential from muon decays. 1 The KAR-MEN Collaboration interpreted the anomaly as being due to an exotic decay of π + -mesons into a muon and a 33.9 MeV new fermion X and reported a signal curve for pion branching ratio BR(π + → µ + + X) × Γ(X → e + e − ν) as a function of X-lifetime with a branching ratio BR(π + → µ + + X) as small as 10 −16 [23]. This and other hypotheses explaining the anomaly have been recently extensively investigated both theoretically [5,25,26] and experimentally [27,29].…”

Section: The Karmen Time Anomalymentioning

confidence: 99%

See 1 more Smart Citation

Search for heavy neutrinos mixing with tau neutrinos

et al. 2001

View full text Add to dashboard Cite

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...

show abstract

“…In 1995 KARMEN for the first time reported [1] an anomaly in the time distribution of single prong events concerning the time interval corresponding to muon decay. Even with a much improved active detector shielding the anomaly has persisted in new KARMEN data [2].…”

Section: Introductionmentioning

confidence: 99%

Search for exotic muon decays

Bilger¹,

Föhl²,

Clement³

et al. 1999

Physics Letters B

View full text Add to dashboard Cite

Recently, it has been proposed that the observed anomaly in the time distribution of neutrino induced reactions, reported by the KARMEN collaboration, can be interpreted as a signal from an exotic muon decay branch µ + → e + X. It has been shown that this hypothesis gives an acceptable fit to the KARMEN data if the boson X has a mass of m X = 103.9 MeV/c 2 , close to the kinematical limit. We have performed a search for the X particle by studying for the first time the very low energy part of the Michel spectrum in µ + decays. Using a HPGe detector setup at the µE4 beamline at PSI we find branching ratios BR(µ + → e + X) < 5.7 · 10 −4 (90% C.L.) for most of the region 103 MeV/c 2 < m X < 105 MeV/c 2 .

show abstract

Anomaly in the time distribution of neutrinos from a pulsed beam stop source

Cited by 61 publications

References 13 publications

Supernovas and light neutralinos: SN 1987A bounds on supersymmetry reexamined

Supernovas and light neutralinos: SN 1987A bounds on supersymmetry reexamined

Search for heavy neutrinos mixing with tau neutrinos

Search for exotic muon decays

Contact Info

Product

Resources

About