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How did we come to the ideas of

How did we come to the ideas of. quarks , strings?. Myron Bander U.C. Irvine. Lots of data. Arcane rules correlating the data. More economical set of rules. Model. Explanation from more fundamental principles. Model.

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How did we come to the ideas of

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  1. How did we come to the ideas of • quarks, • strings? MyronBander U.C. Irvine QuarkNet

  2. Lots of data. Arcane rules correlating the data. More economical set of rules. Model. Explanation from more fundamental principles. Model. Is the the model consistent, consistent with experiment? Is it predictive? If yes! Theory! Fundamental particles. Too many. Introduce constituents. Too many. Go back two steps. How do we come up with any ideas in physics? stumble on them molecules to atoms to electron and nuclei to proton, neutron, electron to quarks to ? QuarkNet

  3. Particles: Spin: Quantum Mechanics Spin=0, 1/2, 1, 3/2, …. QuarkNet

  4. Elementary Particle Zoo circa 1960: Spin-1/2 Spin-0 QuarkNet

  5. Resonances: Spin-1 Spin-3/2 QuarkNet

  6. Symmetries: Horizontal: Isospin back to 1930’s Challenge: Find a symmetry for the whole group. Many attempts (1957-1961) 1961 M. Gell-Mann, Y. Ne’eman: (flavor) SU(3) symmetry QuarkNet

  7. SU(3) Symmetry(Cartan, ~1900): Allowed groups: 1, 3, 6, 8, 10, . . . o o o o o o o o Octet o o o o o o o o o o Decuplet QuarkNet

  8. Comparison with known (1961) particles: OK QuarkNet

  9. Predictions: …many more borne out prediction. QuarkNet

  10. What about the 3? ..can build up ALL known particles out of these: spin 1/2 …… Get a reasonable picture of many properties of nucleons and mesons --- particle chemistry. QuarkNet

  11. Are the 3’s real? …charge 1/3, 2/3 ? …just mathematics, just mathematics … real particles are in 8’s, 10’s (eight-fold-way) 1964: maybe the 3’s are real Gell-Mann, Zweig quarks QuarkNet

  12. Two flies in the ointment … Pauli Exclusion Principle Where are the quarks? QuarkNet

  13. Where are the quarks? Search for in: old rocks, sea shells, lunar rocks, ….. less than one part in Try to produce them in accelerators: less than one part in QuarkNet

  14. Pauli Exclusion Principle: Hydrogen Helium No two electrons with the same spin can occupy the same orbit. Beryllium Lithium QuarkNet

  15. extended to quarks: …no two identical quarks with the same spin can be in the same orbit…. what about: O.W Greenberg, Gell-Mann QuarkNet

  16. color: (+flavor) QuarkNet

  17. Confinement: Forces between quarks: no force bungeechord glue(on) confined pull too far ? QuarkNet

  18. Test in electron-positron annihilation: hadrons QuarkNet

  19. R=3 1/3 R=2 to date: 6 quarks b quark threshold c quark threshold QuarkNet

  20. Other tests and consequences: Off by a factor of 3 without color. “And since these things are so, it is necessary to think that in all the objects that are compound there exist many things of al sorts, and germs of all objects, having all sorts of forms and colors and flavors”. Anaxagoras (5th century BC) First evidence for quark-like substructure QuarkNet

  21. Strings: } • Veneziano Model • Dual Resonance Model • ‘bungee chords’ 1970 elementary particles behave like vibrating strings (studied for a long time). QuarkNet

  22. Classical and Quantum Strings: Strings consistent with the theory of relativity: Nambu, Goto OK Strings consistent with the theory of relativity and with quantum mechanics ..number of dimensions, unwanted particles QuarkNet

  23. Theory Of Everything: 1980: …extra dimensions, unwanted particles may fit into a theory of gravity TOE ….still major problems. String theory maybe a 21st century theory, requiring 21st century mathematics, that was accidentally discovered in the 20th century. Ed Witten QuarkNet

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