11.2.5—The changes to quark composition that take place during β– and β+ decay

In β− decay a down quark changes to an up quark, turning a neutron udd into a proton uud and emitting an electron and antineutrino; β+ reverses the quark change with a positron and neutrino.

Track the quark charge change and the emitted lepton charges together. The weak interaction mediates the flavour change.

A neutron’s d→u raises hadron charge by +e, balanced by the emitted electron’s −e in β− decay.

The beta electron is not an orbital electron released from the atom; it is created in the weak decay process.