beta decay 
noun [mass noun]
Radioactive decay in which an electron is emitted.Some atoms can undergo radioactive beta decay, in which a neutron decays into a proton, an electron and an electron-antineutrino via the weak nuclear force....
- There are various mechanisms and forms of beta decay (e.g., negative beta decay, neutron beta decay, double beta decay, inverse beta decay, etc.).
- Physicists originally had a lot of trouble reconciling relativistic quantum field theory with the weak interaction that is responsible, for example, for what is called beta decay of neutron into proton, electron and neutrino.