1. Elementary particles atom Hadrons Leptons Baryons Mesons Nucleons
Key dates
1808 Dalton's Plum Pudding model.
1897 Thomson's electron discovery.
1910 Rutherford's scattering of α particles with Geiger & Marsden, Manchester.
1913 Bohr theory of the atom.
1919 Rutherford – discovery of proton.
1930 Dirac predicts positron.
1931 Pauli predicts neutrino.
1932 Fermi names predicted neutrino.
1932 Anderson observes positron.
1932 Chadwick – discovery of neutron.
1955 Segre & Chamberlain – observed anti-proton.
1956 Neutrino observed.
1960 Salam & Weinberg predicted W & Z bosons.
1975 Perl – discovery of Tau 1784MeV/c².
1983 CERN W & Z bosons observed.
???? Higgs Boson (not quite yet).
Forces:
1. strong (hadronic) nuclear interaction (carried by exchange bosons called gluons).
2. electromagnetic interaction (carried by exchange particle photon).
3. weak nuclear interaction (carried by W & Z exchange bosons).
4. gravitational interaction (carried by predicted graviton exchange boson).
atom
Hadrons
Strong, 'hadronic' interactions
(made of quarks 'up', 'down' & 'strange' (flavors) 'top', 'bottom' & 'charm' (newer).)
Leptons
Spin ½ 's …so 'fermions'.
Weak interactions.
Fundamental particles.
No size. Mostly light.
Each has an anti-particle.
Baryons
Spin ½ 's …so 'fermions'.
Heavy hadrons.
Triplets of quarks.
Mesons
Spin 0,1,2,..so 'bosons'..
Intermediate mass.
Quark & anti-quark.
Muon νμ Neutrino
Electron e
Muon μ
Tau τ
(heavy)
Nucleons
Others
Electron neutrino νe
Tau neutrino ντ
Neutron
udd
Proton uud
Quarks
Fundamental particles.
Up, down, strange, top, bottom, charm
Lambda uds
Sigma Xi
Pion ud
Kaon
Eta

2. Conservation laws Charge Fermions?
Apparatus:
Cloud chambers
Bubble chambers
Charge
Electrostatic charge
Properties conserved during reactions and decays of elementary particles:
Charge
Energy
Angular momentum
Linear momentum
Lepton number
Baryon number
Strangeness (not Universal)
Fermions?
Pauli exclusion?
Strangeness discovered Gellman & Nishijima (1952).

3. Field particles The Standard Model Feynman Diagrams
Quantum dynamics:
Virtual photons (quantum electrodynamics)
Graviton (gravitational interaction)
Vector boson (weak interactions)
Gluon (strong interactions between quarks)
The Standard Model
Including:
Quark model
Electroweak theory
Quantum chromodynamics
Feynman Diagrams