Under this theory, if neutrinos and antineutrinos behave differently today, then a similar imbalance in their ancient counterparts could explain the overabundance of matter.

This is the first indication that the presumed asymmetry or imbalance between neutrinos and antineutrinos is actually there.

The neutrinos and antineutrinos, however, would not have annihilated with each other, because these particles interact with themselves and with other particles only very weakly.