elementary particles

elementary particles

1. chracteristics

   • cannot be decomposed into simpler objects
   • can interact and under mutual conversion
   • can have particular structure

2. classification

   • mainly by rest mass and spin
     • spin: specific KE
   • photons
     • restmass: 0
     • spin: 0
   • leptons
     • rest mass almost 0
     • spin: 1/2
     • neutrinos
     • electrons
     • muons
   • hadrons
     • 2 (mesons) or 3 (baryons) quarks
   • mesons
     • muons < rest mass < protons
     • pions
     • kaons
   • Baryons
     • high rest mass, spin number is 0
     • nucleons: neutrons and protons
     • hyperons

3. Quarks

   • gluons: force acting among quarks
   • have fractional charges: u,c,t,d,s,b

4. have antiparticles

   • composed of antimatter
   • interaction b/t particles and antiparticles leads to conversion into photon or other particles.