Quarks and antiquarks

Quarks and antiquarks

1. Particle exchange

   • They are how forces act between two particles
   • Virtual particles
     • Exist for very short period of time, only long enough to transfer energy, momentum etc.
   • The four fundamental forces (gravity, electromagnetic, strong nuclear and weak nuclear have their own exchange particles
     • Gauge bonds
   • The size of exchange particles determines the range of force
     • Heavier exchange particles have a shorter the range

2. Exchange particles

   • Diagram

3. Particle interaction diagram rules

   • Exchange particles are wiggly lines
   • Other particles are shown by straight lines
   • Incoming particles start at the bottom of the diagram and upwards
   • W bosons carry charge from one side of the diagram to the other- to make the charge is balanced
   • W- moving to the left has the same effect as a W+ moving to the right

4. Electromagnetic repulsion

5. Beta-minus decay

6. Electron capture

   • Diagram
   • Prtoton rich nuclei can capture an electron and change it into a neutron
   • The proton is acting on the electron so the W boson comes from the proton
   • An electron neutrino is emitted to conserve electron lepton number

7. Electron - proton collision

   • In an electron proton collision, the electron is the acting particle because it is being fired at the proton
   • The W boson comes from the electron to conserve charge
   • Diagram

8. Key terms

   • Exchange particles- virtual particles interact with particles to produce the effects of attraction or repulsion
   • Virtual particles
   • Gauge bonds
   • Electron capture
   • Electron- proton capture