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Physics LibreTexts

1.2: A Timeline of Particle Physics

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Year Experiment Theory
1927 β decay discovered
1928 Paul Dirac: Wave equation for electron
1930 Wolfgang Pauli suggests existence of neutrino
1931 Positron discovered
1931 Paul Dirac realises that positrons are part of his equation
1931 Chadwick discovers neutron
1933/4 Fermi introduces theory for β decay
1933/4 Hideki Yukawa discusses nuclear binding in terms of pions
1937 μ discovered in cosmic rays
1938 Baryon number conservation
1946 μ is not Yukawa’s particle
1947 π+ discovered in cosmic rays
1946-50 Tomonaga, Schwinger and Feynman develop QED
1948 First artificial π’s
1949 K+ discovered
1950 π0γγ
1951 ”V-particles” Λ0 and K0
1952 Δ: excited state of nucleon
1954 Yang and Mills: Gauge theories
1956 Lee and Yang: Weak force might break parity!
1956 CS Wu and Ambler: Yes it does.
1961 Eightfold way as organising principle
1962 νμ and νe
1964 Quarks (Gell-man and Zweig) u,d,s
1964 Fourth quark suggested (c)
1965 Colour charge all particles are colour neutral!
1967 Glashow-Salam-Weinberg unification of electromagnetic and weak interactions. Predict Higgs boson.
1968-69 DIS at SLAC constituents of proton seen!
1973 QCD as the theory of coloured interactions. Gluons.
1973 Asymptotic freedom
1974 J/ψ (cˉc) meson
1976 D0 meson (ˉuc) confirms theory.
1976 τ lepton!
1977 b (bottom quark). Where is top?
1978 Parity violating neutral weak interaction seen
1979 Gluon signature at PETRA
1983 W± and Z0 seen at CERN
1989 SLAC suggests only three generations of (light!) neutrinos
1995 t (top) at 175 GeV mass
1997 New physics at HERA (200 GeV)

This page titled 1.2: A Timeline of Particle Physics is shared under a CC BY-NC-SA 2.0 license and was authored, remixed, and/or curated by Niels Walet via source content that was edited to the style and standards of the LibreTexts platform.

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