Download presentation
Presentation is loading. Please wait.
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Zweig CERN preprint : "Aces" ( unpublished )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
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.