Particle Physics

Particle Physics

1. Forces

   • Gravitational
     • Interacts with all:
   • Electromagnetic
     • Only Acts on charged
   • Strong Nuclear
   • Weak Nuclear
     • Acts on all
   • Mediated by: Exchange Bosons
     • Photon
       • Massless, chargless
     • Graviton??
     • Gluon
       • Exchanged between Quarks/Antiquarks in small range
       • Can Change Colour
     • W and Z
       • Heavy, short range
       • W+ pos, W- neg, Z neutral
       • Beta Decay

2. Particles

   • Antiparticles: Same mass but opposite charge
     • If collide, can annihilate producing photon with energy e = mc^2
     • Denote by bar over
   • Fundamental/Elementry
     • Leptons
       • Charged ( - 1 )
         • Fam 1: Electron
         • Fam 2:Muon
         • Fam 3: Tauon
       • Uncharged
         • Fam 1: Electron Neutrino
         • Fam 2: Muon Neutrino
         • Fam 3: Tauon Neutrino
       • ( + anti)
       • Conservation Law: Lepton Number for each family must be conserved
       • Eg
         • Electron
         • Positron
         • Nuetrino
   • Hadrons
     • Baryons
       • Fermions (1/2 Integer Spin)
         • Pauli Exclusion Principle: Only one particle can exist in a particular quantum state at one time
       • Contain 3
         • Quarks
           • Gen 1: Up/Down
           • Gen 2: Charm/Strange
           • Gen 3: Top/Bottom
       • Integer Charge
       • Spins of 1/2 or 3/2
       • Baryon Number must be conserved
     • Mesons
       • Bosons (Integer Spin)
       • Contain pair
       • Neutral Charge

3. Reactions

   • Symmetries
     • Time Reversal
     • Charge Reversal
   • Feynmans Diagrams
     • Straight Lines: Particles before and after reaction
     • Wavy Lines: Particle Exchange
     • Charge must be conserved