Particle Physics - A2 - OCR

Hadrons
1. Baryons
  1. Nucleons - protons and neutrons
  2. All baryons decay to protons
  3. Baryon number
    1. the number of baryons in a reaction never changes
    2. The proton and neutron each have a baryon number of 1
2. Mesons
  1. They are unstabe
  2. Baryon number
    1. All mesons have a baryon number of 0 as they aren't baryons
  3. Pions and Kaons
    1. Pions are the lightest mesons
      1. There are 3 types with different charges - π0, π+, and π−
    2. Kaons are heavier and more unstable
      1. There are also 3 types with different charges - K+, K0, K−
3. Hadrons are particles that are held together by strong nuclear force
Letptons
1. Leptons do not feel the strong nuclear force.
2. There are 3 types of Lepton - electron, muon and tau which all have a leton number of 1
  1. the electron, muon and tau all have a charge of -1
  2. Neutrinos - these have almost zero mass and zero electric charge
    1. each types of lepton has a neutrino form as well, with a charge of 0
    2. they have the same lepton number as the non neutrino form though
Anti particles
1. Every particle has an anti particle, that will have opposite charge, but the same lepton or baryon number
2. Mesons are their own antipartices
3. Energy can be converted into matter as E=mc2
  1. However, when energy is converted into matter, you will produce equal amounts of anti matter and matter
4. Particle-Antiparticle Pair is produced from a single photon, if there is enough energy
5. Pair Annihilation happens when a particle meets an antiparticle, all the mass is converted to energy
  1. For instance an electron and positron will combine to form a gamma ray
Quarks
1. Quarks are the fundamental particles, that make hadrons
  1. There are many types - up, down and strange (the ones to know) and a few others called top,bottom and charm
  2. Baryons are made from 3 quarks
    1. Protons-uud
    2. Neutron-udd
    3. antiprotons and antineutrons are made up of the equivalent antiquarks
2. Antiparticles are made up of antiquarks
  1. Note: antiquarks have the opposite charge and baryon number!
3. Quarks have charge and a baryon number - strange also has a strangeness value of 1
  1. Charge: Up=+2/3 Down=-1/3 Strange=-1/3
  2. Baryon Number: all =+1/3
4. Mesons are a quark and an antiquark
  1. Pions are made from up and down quarks
  2. Kaons have strangeness

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Particle Physics - A2 - OCR

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