How Neutrinos Could Solve The Three Greatest Open Questions In Physics
“Perhaps ironically, the greatest advance in particle physics — a great leap forward beyond the Standard Model — might not come from our greatest experiments and detectors at high-energies, but from a humble, patient look for an ultra-rare decay. We’ve constrained neutrinoless double beta decay to have a lifetime of more than 2 × 1025 years, but the next decade or two of experiments should measure this decay if it exists. So far, neutrinos are the only hint of particle physics beyond the Standard Model. If neutrinoless double beta decay turns out to be real, it might be the future of fundamental physics. It could solve the biggest cosmic questions plaguing humanity today. Our only choice is to look. If nature is kind to us, the future won’t be supersymmetry, extra dimensions, or string theory. We just might have a neutrino revolution on our hands.”
When we look at the Standard Model of particle physics, there’s a big problem that leaps out at us right away: it works well. It works so practically perfectly well that it leaves us very little room for solving some of the problems we have in the Universe: problems like dark matter, dark energy, and the origin of matter. The only hint we have that the Standard Model isn’t fully correct comes from our observations of neutrinos: they have very tiny masses, and they oscillate from one flavor into another. Furthermore, they only come in one chirality: neutrinos are always left-handed and anti-neutrinos are always right-handed. This could be explained if neutrinos weren’t normal (Dirac) fermions like the other Standard Model particles, but were their own antiparticles, and behaved as Majorana fermions. If this scenario is true, it could not only solve the dark matter, dark energy, and matter/antimatter asymmetry problems all at once, but there’s an experimental signature we can look for.