WHAT DO THE MUON NEUTRINOS OSCILLATE WITH?
We cannot yet resolve whether the muon neutrinos oscillate into tau neutrinos or a new sterile neutrino. The betting would be generally on tau neutrinos, for reasons of economy, not introducing new unmotivated hypotheses (Occam’s Razor). Tau neutrinos only produce tau particles at energies higher than we have much data in SuperKamiokande (because the tau is a very heavy particle, almost twice the mass of a proton). Hence, as yet, we have not yet detected the presence of taus. Taus are hard to detect in any case as the tau immediately (3 x 10^-13 sec, after travelling 0.1 mm) decays after production, and generally into many particles in a shower which looks like an electron neutrino interaction in our detector. (Indeed no experiment has yet directly detected tau neutrinos.) By a sterile neutrino we mean one which does not even partake of the weak force, one which is only accessable to us via oscillations, possibly oscillating into a mirror world, completely out of detection from our wor
