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 click a button (0-9 or A-J) to vote for your answer this flashes green when you vote you can change your vote (until polling closes) by pressing another button 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? 1. Tea 2. Coffee 3. Fruit Juice 4. Water 5. Other 6. 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) 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… Neutrinos only interact by the weak force – once produced we never see them again…

10. WW Events at LEP Each W can decay to e,  plus a neutrino LEPTONIC DECAY Each W can decay to two quarks HADRONIC DECAY The decays are so fast you’ll only see the final products in the detector…

11. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

12. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

13. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

14. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

15. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

16. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

17. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

18. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

19. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

20. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay

21. Events 11-20 (30 sec)

22. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

23. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

24. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

25. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

26. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

27. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

28. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

29. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

30. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

31. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 10

32. Events 21-30 (15 sec)

33. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

34. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

35. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

36. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

37. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

38. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

39. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

40. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

41. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

42. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

43. Events 31-40 (15 sec)

44. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

45. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

46. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

47. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

48. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

49. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

50. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

51. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

52. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

53. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 7

54. Events 41-50 (15 sec)

55. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

56. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

57. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

58. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

59. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

60. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

61. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 8

62. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

63. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

64. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

65. Events 51-60 (15 sec)

66. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

67. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

68. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

69. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

70. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

71. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

72. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

73. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

74. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

75. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

77. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

78. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

79. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

80. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

81. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

82. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

83. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

84. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

85. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

86. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

88. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

89. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

90. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

91. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

92. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

93. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

94. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

95. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

96. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

97. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

99. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

100. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

101. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

102. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

103. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

104. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

105. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

106. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

107. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

108. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

110. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

111. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

112. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

113. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

114. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

115. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

116. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

117. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

118. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

119. What sort of WW decay is this? 1. Double hadronic decay 2. Mixed 3. Double leptonic decay 5

120. Results We know there are three sorts of leptons (e,  so there are 9 ways to get double leptonic events DL = 9 If there are N quarks we expect N double hadronic events DH = N & mixed decays M = 2 x 3 x N = 6 N 2 2 We got… N=? N=? N=? We saw ?

121. What should we have got? LEP has enough energy to make four quarks up down charm strange BUT – there is an additional factor of three because each quark has three different sorts of charges associated with the strong force RED GREEN BLUE N = 6