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The Standard Model
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| Matter | Three generations of fermions: |
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Quarks are strongly interacting. They
make up hadrons: nuclear matter and mesons. Leptons interact by weak or electromagnetic forces. The neutrinos are uncharged, (nearly) massless, and interact very little. | |
| Forces |
Gauge bosons generate a symmetry group: SU(3) x SU(2) x U(1) |
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Electromagnetic Interactions are mediated by the massless photon,
a U(1) gauge boson. Weak Interactions are mediated by the massive W and Z boson. They are unified with the photon in an SU(2) x U(1) symmetry group. Spontaneous symmetry breaking via Higgs mechanism generates masses for W, Z bosons. Strong Interactions between quarks are mediated by eight gluons which are identified with the generators of an SU(3) symmetry group. | |
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