Quantum Particle Behavior
Text Reading: Giancoli, Physics - Principles with Applications, Chapter 32: Sections 8 to 12
- 32.8 New patterns of behavior led to identification of new conserved characteristics, which, since they have no analogy in common experience, have odd names: strangeness and charm.
- 32.9 To explain the wide variety of hadron behaviors, M. Gell-Mann proposed the existence of quarks, which combine to form the other subatomic particles. Quarks are distinguished by their mass, charge, baryon number, strangeness, charm, and top or bottom characteristics. Different behaviors of mesons can be explained by quark-antiquark paris, those of baryons by combinations of three quarks. Quarks, together with gauge bosons, the Higgs boson, and leptons are "fundamental", since hadrons are made of quarks.
- 32.10 The Standard model uses further quark characteristics (color and flavor) to associate specific behaviors with quark types. Other classifications emphasize whether particles follow the Pauli exclusion principle and have half-integer spins (Fermions) or violate the principle and have integer spins (bosons). Using color distinctions prevents quarks from violating the principle and maes them fermions. Quarks have not been observed in isolation, only in combinations. This quantum chromodynamic (QDC) theory, together with the theory that the electromagnetic force and weak nuclear force can be combined (the electroweak theory) make up the Standard Model.
- 32.11 One goal of modern physics is to find a way to understand the four fundamental forces as a single force in a grand unified field theory. The event which split the forces apart during the early universe is cause the symmetry-breaking event. Amont the predictions of the GUT is that phtons will eventually decay, but the period is on the order of the age of the universe. Other problems the GUT must address is the matter-antimatter issue: why is there so little antimatter in the current universe?
- 32.12 Altenatives to the Standard Model include string theory, in which the fundamental entities are not particles with masses in a confined volume, but strings vibrating with different patterns; and supersymmetry thories (SUSY). Each of these alternatives address problems in the Standard Model, but fail to address other issues.
t: particle lifetime
Read the following weblecture before chat: Conservation in Particle Behavior
Use the Standard Model option at The Particle Adventure to discover how physicists experiment with and describe particle interactions.
Chat Preparation Activities
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