2. 18 May, 2003QuarkNet1 How did we come to the ideas of  quarks,  strings? Myron Bander U.C. Irvine

3. 18 May, 2003QuarkNet2 How do we come up with any ideas in physics? 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. stumble on them molecules to atoms to electron and nuclei to proton, neutron, electron to quarks to ?

4. 18 May, 2003QuarkNet3 Particles: Spin: Quantum Mechanics Spin=0, 1/2, 1, 3/2, ….

5. 18 May, 2003QuarkNet4 Spin-0 Spin-1/2 Elementary Particle Zoo circa 1960:

6. 18 May, 2003QuarkNet5 Resonances: Spin-1 Spin-3/2

7. 18 May, 2003QuarkNet6 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 Symmetries :

8. 18 May, 2003QuarkNet7 SU(3) Symmetry(Cartan, ~1900): Allowed groups: 1, 3, 6, 8, 10,... o o o o o o o o o o o o Octet Decuplet

9. 18 May, 2003QuarkNet8 OK Comparison with known (1961) particles:

10. 18 May, 2003QuarkNet9 Predictions: …many more borne out prediction.

11. 18 May, 2003QuarkNet10 What about the 3? spin 1/2..can build up ALL known particles out of these: …… Get a reasonable picture of many properties of nucleons and mesons --- particle chemistry.

12. 18 May, 2003QuarkNet11 Are the 3’s real? …just mathematics, just mathematics … …charge 1/3, 2/3 ? real particles are in 8’s, 10’s (eight-fold-way) 1964: maybe the 3’s are real Gell-Mann, Zweig quarks

13. 18 May, 2003QuarkNet12 Two flies in the ointment … Where are the quarks? Pauli Exclusion Principle

14. 18 May, 2003QuarkNet13 Where are the quarks? Search for in: old rocks, sea shells, lunar rocks, ….. Try to produce them in accelerators: less than one part in

15. 18 May, 2003QuarkNet14 Pauli Exclusion Principle: HydrogenHelium Lithium Beryllium No two electrons with the same spin can occupy the same orbit.

16. 18 May, 2003QuarkNet15 extended to quarks: …no two identical quarks with the same spin can be in the same orbit…. what about: O.W Greenberg, Gell-Mann

17. 18 May, 2003QuarkNet16 color: (+flavor)

18. 18 May, 2003QuarkNet17 Confinement: Forces between quarks: bungee chord no force confined ? glue(on) pull too far

19. 18 May, 2003QuarkNet18 hadrons Test in electron-positron annihilation:

20. 18 May, 2003QuarkNet19 R=2 R=3 1/3 c quark threshold b quark threshold to date: 6 quarks

21. 18 May, 2003QuarkNet20 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 (5 th century BC) First evidence for quark-like substructure

22. 18 May, 2003QuarkNet21 Strings: Veneziano Model Dual Resonance Model ‘bungee chords’ } 1970 elementary particles behave like vibrating strings (studied for a long time).

23. 18 May, 2003QuarkNet22 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

24. 18 May, 2003QuarkNet23 String theory maybe a 21 st century theory, requiring 21 st century mathematics, that was accidentally discovered in the 20 th century. Ed Witten Theory Of Everything: 1980: …extra dimensions, unwanted particles may fit into a theory of gravity TOE ….still major problems.