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[1007.1150] Event Excess in the MiniBooNE Search for $\bar \nu_μ\rightarrow \bar \nu_e$ Oscillations
 
Authors:The MiniBooNE Collaboration
Abstract:The MiniBooNE experiment at Fermilab reports results from a search for $\bar \nu_\mu \rightarrow \bar \nu_e$ oscillations, using a data sample corresponding to $5.66 \times 10^{20}$ protons on target. An excess of $20.9 \pm 14.0$ events is observed in the energy range $475<E_\nu^{QE}<1250$ MeV, which, when constrained by the observed $\bar \nu_\mu$ events, has a probability for consistency with the background-only hypothesis of 0.5\%. On the other hand, fitting for $\bar{\nu}_{\mu}\rightarrow\bar{\nu}_e$ oscillations, the best-fit point has a $\chi^2$-probability of 8.7\%. The data are consistent with $\bar \nu_\mu \rightarrow \bar \nu_e$ oscillations in the 0.1 to 1.0 eV$^2$ $\Delta m^2$ range and with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory.
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Molly Swanson



Joined: 22 Jun 2009
Posts: 9
Affiliation: University College London

PostPosted: November 04 2010  Reply with quote

New MiniBooNE results now show some hints of sterile neutrinos!
http://arxiv.org/abs/1007.1150
http://www.sciencedaily.com/releases/2010/11/101102185722.htm

I nearly missed this due to its understated title and abstract that don't even allude to the possible cosmological significance, but this could be very interesting for cosmology if sterile neutrinos could be dark matter.

In 2007 MiniBooNE announced their oscillation results from a neutrino beam were not consistent with LSND, which disfavored sterile neutrinos. But recently (well, last summer, but I am a bit behind on particle physics news, apparently) they announced results using an antineutrino beam that DO support the LSND results. Maybe there are sterile neutrinos after all?

I don't think the case is rock-solid yet, but we cosmologists should definitely be paying attention to this!
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Boud Roukema



Joined: 24 Feb 2005
Posts: 82
Affiliation: Torun Centre for Astronomy, University of Nicolaus Copernicus

PostPosted: November 05 2010  Reply with quote

This Nature comment prior to 1007.1150 lists several independent lines of evidence: http://www.nature.com/news/2010/100317/full/464334a.html , including WMAP7. It refers to the earlier MiniBooNE paper 0906.1997.
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