Ernest RutherfordProposed the neutron

James ChadwickDiscovered the Neutron

B Field into pageLead plate in center -> Energy loss -> mass

Positron Discovery

Hideki Yukawa

Hideki Yukawa

Note missing momentum (neutrino)

First observationof kaon decay to two pions

K+

ππ

π

First observationof kaon decay to three pions

K+

π+

π0→γγ→e+e-e+e-

K+

p

π+

ΛK0 π0→γγ→

e+e-e+e-

Murray Gell-Mann

Yuval Ne’eman

MesonOctet

BaryonOctet

BaryonDecuplet

BNL - J Particle

SLACψ ParticleJ/ψ

Very long lifetime! Signals “new” physics

W - Invariant mass of final hadronic state

Standard Model Conservation Laws

VEM = −α

r

Vs = −43

αs

r+ kr

0.2 0.4 0.6 0.8 1.0 1.2 1.4�2.0

�1.5

�1.0

�0.5

0.0

0.5

1.0

1.5

r �fm�

V�GeV

�

Vs(r) = −43

αs

r+ kr

Fs(r) →����r�1

kr