Experiment

Theory

$\beta$ decay discovered

Paul Dirac: Wave equation for electron

Wolfgang Pauli suggests existence of neutrino

Positron discovered

Paul Dirac realises that positrons are part of his equation

Chadwick discovers neutron

Fermi introduces theory for $\beta$ decay

Hideki Yukawa discusses nuclear binding in terms of pions

$\mu$ discovered in cosmic rays

Baryon number conservation

$\mu$ is not Yukawa’s particle

${\pi }^{+}$ discovered in cosmic rays

Tomonaga, Schwinger and Feynman develop QED

First artificial $\pi$’s

$K^{+}$ discovered

${\pi }^0\to \gamma \gamma$

”V-particles” ${\Lambda }^0$ and $K^0$

$\Delta$: excited state of nucleon

Yang and Mills: Gauge theories

Lee and Yang: Weak force might break parity!

CS Wu and Ambler: Yes it does.

Eightfold way as organising principle

${\nu }_{\mu }$ and ${\nu }_e$

Quarks (Gell-man and Zweig) $u,d,s$

Fourth quark suggested ($c$)

Colour charge all particles are colour neutral!

Glashow-Salam-Weinberg unification of electromagnetic and weak interactions. Predict Higgs boson.

DIS at SLAC constituents of proton seen!

QCD as the theory of coloured interactions. Gluons.

Asymptotic freedom

$J∕\psi$ ($c\bar{c}$) meson

$D0$ meson ($ūc$) confirms theory.

$\tau$ lepton!

b (bottom quark). Where is top?

Parity violating neutral weak interaction seen

Gluon signature at PETRA

$W^{\pm }$ and $Z^0$ seen at CERN

SLAC suggests only three generations of (light!) neutrinos

t (top) at 175 GeV mass

New physics at HERA (200 GeV)