1.7 Conservation laws in particle physics

What are the conservation laws.

• conservation of charge

• conservation of baryon number

• conservation of lepton number.

What are the four fundamental forces of the universe?

• gravitational

• weak

• strong

• electromagnetic

Gravitational force

• all matter

• infinite range

• is the weakest of the fources.

Weak

• leptons, and quarks

• short range

• change in quark flavour

• 10^-10 lifetime

• if neutrinos are present it is weak.

strong

• 10^-24 lifetime

• all particles are hadrons

• leptons dont feel it

• no change in quark flavour

electromagnetic

• short lifetime 10^-12 10^-18

• if gamma photon emitted it is em

• charged particles only

• no change in quark flavour