W boson
A massive elementary particle (mass ~80 GeV/c²) that mediates the weak nuclear force. W bosons come in two varieties: W⁺ (positive charge) and W⁻ (negative charge). They are responsible for beta decay, where a neutron emits a W⁻ boson to convert to a proton.
Real World
In beta-minus decay inside a nuclear reactor at Hinkley Point C, neutrons emit W⁻ bosons that instantly decay into electrons and antineutrinos — the process that produces the reactor's detectable neutrino flux.
Exam Focus
In beta decay Feynman diagrams, show the W boson connecting the quark vertex to the lepton vertex and label all particles including the neutrino.
How well did you know this?