Mesons and hyperons 1930s: Proton, neutron, electron, neutrino (?) 1940s: Mesons (middle-mass): muon, pion (106 MeV/c2 : 140 MeV/c2) 1947: New mesons (emulsion tracks) Named (Manchester University) V particles 1952: Later named K mesons : K+, K- and K0 (500 MeV/c2) 1953: Hyperons: more , heavier than nucleons ‘mesons’ Named Ʌ, Σ, Ξ Strangeness Kaons, hyperons always produced in pairs Produced in strong interactions: but slow decay some new quantum property conserved? → conserved in strong interactions violated in weak interactions Strangeness strange particles → 1958-62: Resonances
Mesons and hyperons 1930s: Proton, neutron, electron, neutrino (?) 1940s: Mesons (middle-mass): muon, pion (106 MeV/c2 : 140 MeV/c2) 1947: New mesons (emulsion tracks) Named V particles (Manchester University) 1952: Later named K mesons : K+, K- and K0 (500 MeV/c2) 1953: Hyperons: more ‘mesons’ , heavier than nucleons Named Ʌ, Σ, Ξ Strangeness Kaons, hyperons always produced in pairs Produced in strong interactions: but slow decay → some new quantum property conserved? conserved in strong interactions violated in weak interactions Strangeness → strange particles 1958-62: Resonances