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Lecture 4b quarks.

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Presentation on theme: "Lecture 4b quarks."— Presentation transcript:

1 lecture 4b quarks

2 baryons: octets, decuplets mesons: octets
triplets?

3 1964: M. Gell-Mann G. Zweig SU(3) - triplets

4 - M. Gell-Mann G. Zweig M. Gell-Mann G. Zweig

5 quarks Finnegans Wake page 383 ( James Joyce )

6 Zweig CERN preprint : "Aces" ( unpublished )

7 Gell-Mann Physics Letters: "Quarks"

8

9

10 - 1. mesons : qq 2. baryons : qqq

11 -

12 -

13 proton: ( u u d ) neutron: ( d d u )

14

15 SU(3) udd uud dds uds uus dss uss baryons

16 decuplet ddd udd uud uuu uus dds uds dss uss sss

17 Omega Minus: totally symmetric
problem: Pauli statistics

18 mesons: quark-antiquark

19 vector mesons

20

21

22

23 singlet octet triplet

24

25 SU(6) symmetry

26

27 n = ( u <=> d )

28 ( s-wave) sum (u + d) = 1/2 = spin

29 Neutron:

30 experiment => magnetic moments : (in magneton m) proton: m neutron: m

31 Magnetic moments: lambda: m sigma +: m sigma -: m (in magneton m)

32 SU(6):

33 2/3 -1/6 Exp.: ==>

34 Exp: -1.47 (agreement within 2%!)

35 Exp.: lambda/proton=-0.22 ==> m(u) / m(s) = 0.66

36 magnetic moments of sigma, chi agree
u / d: MeV s: MeV s - u/d: MeV chiral symmetry magnetic moments of sigma, chi agree very well with the SU(6) prediction

37 . . . Exp.: m(s) ~ 510 MeV

38 SLAC

39 ==>> quarks "observed"

40 - J. Bjorken: current algebra R. Feynman: parton model

41 - 1970 light cone current algebra Fritzsch / Gell-Mann 1970

42 current commutators near the light cone are
abstracted from the free quark model explains scaling behaviour of cross sections

43

44

45 lecture 5 quarks H. Fritzsch

46

47 - 1. mesons : qq 2. baryons : qqq

48 SU(3) udd uud dds uds uus dss uss baryons

49 Omega Minus: totally symmetric
problem: Pauli statistics

50

51 2/3 -1/6 Exp.: ==>

52 Exp: -1.47 (agreement within 2%!)

53 SLAC

54 deep inelastic scattering

55 q e

56

57 Richard Taylor, SLAC

58 - 1970 light cone current algebra Fritzsch / Gell-Mann 1970

59 current commutators near the light cone are
abstracted from the free quark model explains scaling behaviour of cross sections

60

61

62

63

64 energy-momentum tensor

65 heavy quarks

66 SPEAR at SLAC SPEAR at SLAC in 1972

67 J/PSI e(-) e(+) M= 3.1 GeV

68 heavy quarks SLAC MIT November 1974

69 Perl Richter Goldhaber

70 Samuel Ting, MIT

71

72

73 charmed quark: charm-anticharm mesons similar to positronium

74

75 Crystal Ball

76

77

78 1977: Fermilab muon – pairs => Upsilon meson (ϒ) mass: GeV

79

80 Leon Lederman

81 Upsilon meson (ϒ) mass: GeV b – quark (charge: -1/3 e)

82

83 M(b) : ~ 4.2 GeV

84

85 Fermilab

86 CDF – detector Fermilab

87 FNAL 1995 t b m(t): 172 GeV

88 t-quark: decay very fast – no T-mesons and T-baryons

89 Charged leptons and quarks (MeV)
Masses - Charged leptons and quarks (MeV) tau: muon: electron: - t: c: 1 200 u: 5.3 b: s: d: 7.8 (u, d, c, s - quark masses at 1 GeV)

90

91 173 GeV ln m t b c s d u


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