teachers to involve them and their students in cutting-edge
research in particle physics at
http://
quarknet.fnal.gov/
. The IHEP laboratory in Russia
hosts a chronology of particle physics discoveries:
/
;
ppds/
discovery.html
.
C. Popular article with extensive links
The
Scientific American
article on the future of particle
physics by Steven Weinberg
132
appears on the web with a
variety of links to other literature:
http://
VIII. NOBEL PRIZES RELATED TO THE
STANDARD MODEL
Some contributions in the past 45 years related to the for-
mulation of the Standard Model that have been recognized
by Nobel Prizes in Physics are summarized in Table IV.
More information may be found on the web sites
http://
/
and
.
Many additional prizes were awarded for instrumentation or
discoveries crucial to our present understanding of the stan-
dard model.
IX. SNAPSHOT OF THE STANDARD MODEL
A. Quarks and leptons
The major ingredients of the standard model have been in
place for some time, and can be gleaned from the popular
article by Quigg.
118
The known building blocks of strongly
interacting particles, the
quarks
,
140–142
and the fundamental
fermions lacking strong interactions, the
leptons
, are summa-
rized in Table V. The quark masses quoted there
73
are those
for quarks probed at distances short compared with the char-
acteristic size of strongly interacting particles. When re-
garded as constituents of strongly interacting particles, how-
ever, the
u
and
d
quarks act as quasi-particles with masses of
about 0.3 GeV. The corresponding ‘‘constituent-quark’’
masses of
s
,
c
, and
b
are about 0.5, 1.5, and 4.9 GeV,
respectively.
52
~
For reviews of the spectroscopy of hadrons
containing the heavy quarks
c
and
b
, see Refs. 50, 51, 53,
54.
!
The pattern of charge-changing weak transitions be-
tween quarks with charges
Q
5
2/3 and those with charges
Q
52
1/3 is described by the 3
3
3
Cabibbo-
Kobayashi-Maskawa
,
143,144
or
CKM
matrix; for a review of
its properties, see Ref. 145.
The quarks and leptons in Table V fall into three ‘‘fami-
lies.’’ For evidence that all the existing families
~
at least
those containing light neutrinos
!
may have been discovered,
see Ref. 128.
140.
‘‘A Schematic Model of Baryons and Mesons,’’ M. Gell-Mann, Phys.
Lett.
8
, 214–215
~
1964
!
.
~
I
!
141.
‘‘An SU
~
3
!
Model for Strong Interaction Symmetry and its Breaking:
1,’’ G. Zweig, CERN report 8182/TH 401, 1964
~
unpublished
!
. Re-
printed in
Developments in the Quark Theory of Hadrons
, edited
by D. B. Lichtenberg and S. P. Rosen
~
Hadronic Press, Nonantum,
MA, 1981
!
, Vol. 1, pp. 22–101.
~
I
!
142.
‘‘An SU
~
3
!
Model for Strong Interaction Symmetry and its Breaking:
2,’’ G. Zweig, CERN report 8419/TH 412, 1964
~
unpublished
!
. Re-
printed in
Developments in the Quark Theory of Hadrons
, edited
by D. B. Lichtenberg and S. P. Rosen
~
Hadronic Press, Nonantum,
MA, 1980
!
, Vol. 1, pp. 22–101.
~
I
!
143.
‘‘Unitary Symmetry and Leptonic Decays,’’ N. Cabibbo, Phys. Rev.
Lett.
10
, 531– 532
~
1963
!
.
~
I
!
144.
‘‘CP Violation in the Renormalizable Theory of Weak Interaction,’’
M. Kobayashi and T. Maskawa, Prog. Theor. Phys.
49
, 652–657
~
1973
!
.
~
I
!
Table III. Major non-accelerator laboratories and their public web pages.
Laboratory
Location
Web address
Gran Sasso
Central Italy
/
Kamioka
Western Japan
/
Soudan
Northern Minn.
/
Sudbury
n
Obs.
Ontario
/
Table IV. Nobel prizes in physics since 1957 related to the Standard Model.
Year
Recipient
~
s
!
Subject
1957 T. D. Lee and C. N. Yang
Parity violation
1960 D. A. Glaser
Bubble chamber
1965 R. P. Feynman, J. S. Schwinger,
and S. I. Tomonaga
Quantum electrodynamics
1968 L. W. Alvarez
Discovery of resonances
1969 M. Gell-Mann
Particle classification
1976 B. Richter and S. C. C. Ting
J
/
c
discovery
1979 S. L. Glashow, A. Salam,
and S. Weinberg
Electroweak unification
1980 J. W. Cronin and V. L. Fitch
CP violation
1982 K. G. Wilson
Critical phenomena
1984 C. Rubbia and
W
and
Z
discovery via
S. Van Der Meer
S
p¯ p
S collider
1988 L. M. Lederman, M. Schwartz,
Discovery that
and J. Steinberger
n
m
Þ
n
e
1990 J. I. Friedman, H. W. Kendall,
Deep inelastic electron
and R. E. Taylor
scattering
1992 G. Charpak
Particle detectors
1995 M. L. Perl
t
lepton
F. Reines
Neutrino detection
1999 G. ’t Hooft and
M. J. G. Veltman
Electroweak interactions
2002 R. Davis and M. Koshiba
Cosmic neutrinos
R. Giacconi
Cosmic x-rays
Table V. The known quarks and leptons. Masses in GeV except where
indicated otherwise. Here and elsewhere
c
5
1.
Quarks
Leptons
Charge 2/3
Charge
2
1/3 Charge
2
1
Charge 0
Mass
Mass
Mass
Mass
u
0.0015–0.0045
d
0.005–0.0085
e
0.000511
n
e
,
3 eV
c
1.0–1.4
s
0.085–0.155
m
0.106
n
m
,
190 keV
t
174.3
6
5.1
b
4.0–4.5
t
1.777
n
t
,
18.2 MeV
308
308
Am. J. Phys., Vol. 71, No. 4, April 2003
Jonathan L. Rosner
