Classification of Particles

Classification of Particles

1. Hadrons are particles that feel the strong nuclear force

   • 1. The nucleus of an atom is made up of protons and nuetrons
   • 2.The protons are positively charged so they need a strong force to hold them together
     • This is called the strong nuclear force or strong interaction
   • 3.Not all particles can feel the strong nuclear force
   • 4.Hadrons aren't fundamental particles . Theyre made up of smaller particles called quarks
   • 5.There are two types of hadrons. Baryons & mesons .They're classified according to the number of quarks they have

2. Protons and neutrons are baryons. They are the same except fro differnet electric charges

   • All baryons except the proton are unstable
     • All baryons except protons decay to a proton

3. Antiprotons and antineutrons are antibaryons

   • The antiparticles of protons and neutrons are antibaryons, but antiparticles are annihilated when they meet the corresponding particle- you don't find antibaryons in ordinary matter

4. The number of baryons in an interaction is called the baryon number

   • Baryon number = number of baryons
   • the proton and neutron each have a baryon number B=+1
     • Antibaryons have a bayron number B=-1
       • Other particles B=0
   • Baryon number is a quantum number that mus be conserved in any interaction
   • when an interaction happens the baryon number on either side of the interaction has to be the same
   • The total baryon number in any particle interaction never changes