What is the world made of?

What is the World Made of?

Everything in the world is made of quarks and leptons.
1. For every particle, there is an antiparticle
1. Antiparticles are exactly like their corresponding particles but with an opposite charge
2. The symbol for an antiparticle is the symbol for the particle with a bar over it
1. Ex. The “up antiquark” is designated by u-bar
2. Quarks
   1. Form protons and neutrons
   2. 3 different pairs
      1. up/down
      2. charm/strange
      3. top/bottom
   3. every quark has a corresponding antiquark
   4. quarks have fractional electrical charges (1/3 or 2/3)
   5. quarks have color charges
3. Hadrons
   1. quarks only exist in groups, called Hadrons
   2. hadrons have integer electrical charges formed by the sum of the fractional charges of quarks
   3. no net color charge
   4. two classes of hadrons:
      1. Baryons
         1. Made of 3 quarks
            1. Ex. Proton = 2 up quarks + 1 down quark (uud)
            2. Ex. Neutron = 1 up quarks + 2 down quark (udd)
      2. Mesons
         1. Made of 1 quark and 1 antiquark
         2. Very unstable
            1. Ex. Pion ( +) = an up quark and a down anitiquark
            2. Ex. Antipion ( -) = a down quark and an up antiquark
4. Leptons
   1. point-like particles without internal structure
   2. six leptons
      1. three have electrical charge
         1. electron (e-) (less mass)
         2. muon( ) (more mass)
         3. tau( ) (more mass)
      2. three do not
         1. Neutrinos (v) – very little mass
         2. Every leptons has an antilepton
            1. Ex. Anti-electron = positron</ul></ul>
            2. Divided into 3 lepton families
               1. Electron and its neutrino
               2. Muon and its neutrino
               3. Tau and its neutrino
               4. use the terms "electron number," "muon number," and "tau number" to refer to the lepton family of a particle
                  1. electrons and their neutrinos = +1
                  2. positrons and their antineutrinos = -1
                  3. all other particles = 0
                  4. must be conserved in decay
               5. Lepton Decays
                  1. More massive ones (muon and tau) are very unstable and quickly decay
                  2. Always decays into corresponding neutrino and a particle and its antiparticle
                  3. Number of members in each family must remain constant in decay
                  4. electron number, muon number, and tau number are always conserved when a massive lepton decays into smaller ones
               6. Neutrinos
                  1. A type of lepton
                  2. No charge
                  3. Almost never interact with other particles
                  4. Produced through particle decays
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