Hello, I am in the process of learning about neutrino oscillations. I'm looking for some clarification as a google/forum search hasn't helped me. If someone could advise me or point me in the right direction that would be great! So, if you have neutrinos at energies below the threshold energy for tau neutrino production (about 3.5 GeV), do their oscillation probabilities revert to the two neutrino case? (http://en.wikipedia.org/wiki/Neutrino_oscillation#Two_neutrino_case). The reason i ask this is because there isn't enough energy to make a tau lepton from a tau neutrino/neutron collision, so there is zero probability of that happening. I understand that the flavour of a neutrino can only be determined upon interacting, so am i right? Any help is much apprectiated!