"9σ" in quotation marks as it seems to include the statistical uncertainty only. Article at physicsworld.com The result was shown at the XXVII International Conference on Neutrino Physics and Astrophysics, the slides don't seem to be available and the abstract is not very helpful. RENO measured the energy spectrum of reactor neutrinos, a spectrum that rises quickly from 1 to 3 MeV and then gradually drops off up to ~7 MeV. At around 5 MeV, the observed spectrum does not match the predictions with a discrepancy of up to 15%. My personal guess: something went wrong in the model that predicts this shape. Without this theoretical shape as comparison there is no structure visible at all. Do we really trust the models of reactor neutrino spectra to be accurate within 10% everywhere? If I look at high-energy physics Monte Carlo simulations, where some spectra have deviations of more than a factor of 2 (even between simulations - it is known that it is a problem of the simulations, not the measurements), I'm not sure.