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( unpublished )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"

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

11. -

12. -

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

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

23. singlet
octet
triplet

25. SU(6)
symmetry

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

45. lecture 5
quarks
H. Fritzsch

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

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

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

53. SLAC

54. deep inelastic scattering

55. q e

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

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

73. charmed quark: charm-anticharm mesons similar to positronium

75. Crystal Ball

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

80. Leon Lederman

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

83. M(b) : ~ 4.2 GeV

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)

91. 173 GeV
ln m t b c s d u