Beta decay is a fundamental process in nuclear physics where an unstable atomic nucleus transforms into a more stable state by emitting a beta particle. This process allows an atom to adjust its ratio of protons to neutrons, moving toward the valley of stability defined by its nuclear binding energy. The decay results in the transformation of the nucleus into an isobar of the original nuclide.
During this transformation, a neutron may convert into a proton through the emission of an electron and an antineutrino, or a proton may convert into a neutron via the emission of a positron and a neutrino. These particles are created at the moment of decay rather than existing within the nucleus beforehand. For the process to occur, the Q value or energy release must be positive, ensuring the decay is energetically favorable.