Today at the European Physical Society meeting in Stockholm,
the international T2K collaboration announced definitive observation of muon
neutrino to electron neutrino transformation.
In 2011, the collaboration announced the first indication of this
process, a new type of neutrino oscillation, then; now with 3.5 times more data
this transformation is firmly established.
The probability that random statistical fluctuations alone would produce
the observed excess of electron neutrinos is less than one in a trillion. Equivalently the new results exclude such
possibility at 7.5 sigma level of significance. This T2K observation is the
first of its kind in that an explicit appearance of a unique flavor of neutrino
at a detection point is unequivocally observed from a different flavor of
neutrino at its production point.