Combination of red, yellow blue = white All hadrons white Force between quarks due to colour quantum chromodynamics QCD – QCD: the strong interaction between quarks Transmitted by particles called gluons Zero mass, spin 1 (bosons) Gluon has colour Free gluons not detected: indirect evidence Note: Force between hadrons different from force between quarks 3 new quarks: charm, truth and beauty a) Glashow and Bjorken: leptons and quarks fundamental many similarities 4 lepton 4 quarks? → Also: electroweak theory: symmetry between quarks and leptons? 1970s: neutral weak currents additional channel of disintegration new quark with new flavour? – 1974: new hadronic resonance at SLAC, Brookhaven New particle : Nobel prize) – J/ψ ‘long’lifetime (1976 = meson made of (cc) charm J/ψ 1976: SLAC and Berkeley: neutral charmed meson D0 (cu) D+ and D- later observed
Combination of red, yellow blue = white All hadrons white Force between quarks due to colour – quantum chromodynamics QCD QCD: the strong interaction between quarks Transmitted by particles called gluons Zero mass, spin 1 (bosons) Gluon has colour Free gluons not detected: indirect evidence Note: Force between hadrons different from force between quarks 3 new quarks: charm, truth and beauty a) Glashow and Bjorken: leptons and quarks fundamental many similarities 4 lepton → 4 quarks? Also: electroweak theory: symmetry between quarks and leptons? 1970s: neutral weak currents additional channel of disintegration – new quark with new flavour? 1974: new hadronic resonance at SLAC, Brookhaven New particle – J/ψ : ‘long’lifetime (1976 Nobel prize) J/ψ = meson made of charm (cc) 1976: SLAC and Berkeley: neutral charmed meson D0 (cu) D+ and D- later observed
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