It's a stretch to call this an attempt to explain matter-antimatter asymmetry. First, let's start with how fermions (spin 1/2 particles like electrons and quar

It's a stretch to call this an attempt to explain matter-antimatter asymmetry. First, let's start with how fermions (spin 1/2 particles like electrons and quarks) get mass. They get it through a coupling with the Higgs boson, and the strength of that coupling determines the particle's mass. Neutrinos are fermions, so they could get their mass in the same way. However, that would require a coupling to the Higgs much, much, much smaller than any other fermion has, and so it's a bit of an unsatisfying solution. However, neutrinos could be their own particles (Majorana particles), as the article mentions. If that's the case, they can acquire mass in a different way than all other fermions. Some of the mechanisms (called see-saw mechanisms) that lead to small neutrino masses predict the existence of heavy neutrinos (so heavy that we haven't observed them). Now, a heavy neutrino would decay to the lighter particles we see today. So there aren't any around anymore. But in the early universe, shortly after the big bang, there was enough energy to create them. Particles can preferentially decay to matter instead of antimatter. It's called CP violation, and we observe it in things like heavy mesons. So if the heavy neutrino violates CP when it decays, then that could lead to our universe being made of matter. But I've strung together a lot of hypotheticals: 1. Neutrinos must be Majorana particles. 2. Majorana neutrinos acquire mass through a see-saw mechanism with heavy neutrinos. 3. Heavy neutrinos violate CP when they decay. This experiment might answer #1. Number 2 would probably require studying cosmology. The mass of the heavy neutrinos is probably greater than we could create in a collider on earth (like grand unified theory scale). For number 3, it can be argued that if we observe CP violation in light neutrinos (in this case, CP violation would mean neutrinos oscillate differently than antineutrinos), then heavy neutrinos should exhibit it, too. But we're still trying to look for CP violation in light neutrinos. And it's not clear that CP violation in light neutrinos must imply that heavy neutrinos do it, too. I agree that finding out the nature of the neutrino is important and really cool, but I've always thought trying to argue that double-beta decay experiments are going to solve the matter-antimatter asymmetry problem is hyping things a bit too much. Isn't potentially measuring the mass of neutrinos cool enough?