• The weak interaction?is responsible for the radioactive decay of atoms
• The exchange particle that carries this force is the?W–,?W+?or?Z0?boson
  • The type of exchange particle depends on the type of interaction

   

β decay

• β–?and β+?decay are examples of the weak interaction in action
• In β–?decay, a?neutron?turns into a?proton?emitting an?electron?and an?anti-electron neutrino

• The W–?boson is the exchange particle in this interaction

Feynman diagram showing beta minus decay. The W–?boson is the exchange particle

• In β+?decay, a?proton?turns into a?neutron?emitting a?positron?and an?electron neutrino

• The W+?boson is the exchange particle in this interaction

Feynman diagram showing beta plus decay. The W+?boson is the exchange particle

Electron Capture & Electron–Proton Collisions

• Electrons and protons are attracted to each other via the electromagnetic interaction
  • However, when they interact with each other, it is the weak interaction that facilitates the collision

   

• Both electron capture and electron-proton collisions have the same decay equation

• Electron capture is when?an atomic electron is absorbed by a proton in the nucleus?resulting in the release of a neutron and an electron neutrino
  • This decay is mediated by the W+?boson

   

• Electron-proton collisions are similar; when?an electron collides with a proton, a neutron and an electron neutrino are emitted
  • This decay is mediated by the W–?boson

   

Feynman diagrams for electron capture and an electron-proton collision. These are equal except for the sign of the W boson