Particles + Matter

Particles + Matter

1. Hadrons

   • Baryons
     • Made of 3 quarks
     • Decay into protons
       • because they are the most stable particle
   • Mesons
     • Made of a quark-antiquark
     • Do not decay into protons
     • Kaons
       • Decay into
         • Pions
         • Muon and antineutrino
         • anti muon and neutrino
       • Have a strangeness of +1
     • Pions
       • Decays into muon and antineutrino if charged
       • Neutral pions decay into high energy photons
   • Interact through all 4 fundamental forces
     • Strong Nuclear Force
     • Weak Nuclear Force
       • Hadrons decay through the weak interaction
       • Kaons decay through weak force because they are strange
     • Electromagnetic Force
     • Gravitational Force

2. Leptons

   • Interacts through the weak force only
     • Strangeness is not conserved
   • Neutrinos
     • Muon neutrino
     • Anti muon neutrino
     • Electron neutrino
     • anti electron neutrino
     • very unreactive, millions pass through us every day
     • Very small rest mass, much smaller than that of electron
     • Do not have a charge
   • Muons
     • negative charge
     • 200x more massive than electron
     • Decay into electron or anti neutrino
   • Electrons
   • Produced or annihilated in quark-antiquark interactions
   • Fundamental - i.e can not be broken down into quarks or smaller particles

3. Conservation Laws

   • Charge must be conserved
   • Baryon Number must be conserved
     • Baryons = +1
     • Anti-baryons = -1
     • Leptons have no baryon number
   • Lepton Number must be conserved
     • Electron Lepton
       • electron and electron neutrino = +1
       • positron and anti-electon neutrino = -1
     • Muon Lepton
       • muon- and muon neutrino = +!
       • muon+ and anti-muon neutrino = -1
     • Tau Lepton
       • tau- and tau neutrino = +1
       • tau+ and anti-tau neutrino = -1