Evidence for fermion statistics among neutrinos

[zen loki]

Is there any evidence for quantum fermi-dirac distributions among neutrinos, besides the obvious fact about their spin? I was wondering how Pauli exclusion principle would work with a neutrino 'gas', and what kind of quantum numbers they could have.

It has been expected that if we ever did discover tachyons, that particles with half integer spins would be bosons and full integer spins would be fermions.

Do we have any evidence concerning neutrino quantum statistics?

 

[petergreat]

Fermi-Dirac statistics doesn't have to be tested in bulk materials. At the microscopic level, it manifests itself in the fact that quantum correction due to virtual neutrino pairs (in terms of Feynman diagrams, a neutrino loop) have extra minus signs, in contrast to virtual boson pairs which don't give extra minus signs. I believe this has already been tested in weak interaction, though I don't know what particular reaction provides the experimental test.

Measuring the temperature of the cosmic neutrino background would suffice as a bulk test of Fermi-Dirac statistics for neutrinos. This temperature is expected to be less than the cosmic microwave background temperature, but the exact difference depends on the statistics. However, such a measurement is far beyond the capability of our current technology.