1. Counting Quarks University of Southampton

2. Our goal is to learn about the particles of nature using real data from accelerators We will not explore the theory too much just what you see… Nuclear matter (“hadrons”) is made of quarks – we are going to experimentally determine how many quarks there are…

3. How to vote using your zapper you can change your vote (until polling closes) by pressing another button this flashes green when you vote click a button (0-9 or A-J) to vote for your answer it will not accept invalid answers please don’t press the GO button as it causes problems

4. A question to test your zapper What did you drink with your breakfast this morning? • Tea • Coffee • Fruit Juice • Water • Other • Nothing

5. OPAL

6. Some Simple Events

7. Strong Nuclear Force The force between quarks grows with distance !!!!! Energy builds up between them until many quarks are produced that arrange themselves into strong force neutral hadrons – we see jets…

8. Taus are heavier electrons again – 3500 times heavier… They decay to quarks and electrons/muons in the detector…. Yuk!

9. The Weak Nuclear Force (Beta Decay) Neutrinos only interact by the weak force – once produced we never see them again… The likelihood that a W will decay to quarks or leptons is the same.. If we produce Ws and count the relative probabilities of outcomes we can count how many quarks there are…

10. WW Events at LEP The decays are so fast you’ll only see the final products in the detector… Each W can decay to e, m, t plus a neutrino LEPTONIC DECAY Each W can decay to two quarks HADRONIC DECAY

11. What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

12. What sort of WW decay is this? Double hadronic decay Mixed Double leptonic decay • Double hadronic decay • Mixed • Double leptonic decay

13. What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

14. What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

15. What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

16. What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

17. What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

18. What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

19. What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

20. What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

21. Events 11-20 (30 sec)

22. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

23. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

24. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

25. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

26. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

27. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

28. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

29. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

30. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

31. 10 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

32. Events 21-30 (15 sec)

33. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

34. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

35. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

36. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

37. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

38. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

39. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

40. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

41. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

42. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

43. Events 31-40 (15 sec)

44. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

45. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

46. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

47. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

48. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

49. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay

50. 7 What sort of WW decay is this? • Double hadronic decay • Mixed • Double leptonic decay