DEVELOPMENT OF QUARK MODEL JIN KIM UNIVERSITY OF SOUTH CAROLINA 1 OUTLINE • Particle zoo – Standard model • What is quark? • History of development of quark model 2 PARTICLE ZOO – STANDARD MODEL Elementary particles Fermions Bosons Quarks and Leptons and Gauge bosons Scalar bosons antiquarks antileptons Electron, Up, Down, Photon, W and Z Electron Charm, Strange, bosons, Gluons, Higgs neutrino, Muon, Top, Bottom Graviton Muon neutrino 3 WHAT IS QUARK? https://cnx.org/contents/Q6hKu32v@7/Introduction-to-Particle-Physics 4 WHAT IS QUARK? Up Down Charm Strange To p Bottom 2 1 2 1 2 1 Charge: + + + 3 3 3 3 3 3 1 −1 1 −1 1 −1 Spin: 2 2 2 2 2 2 https://cnx.org/contents/Q6hKu32v@7/Introduction-to-Particle-Physics 5 WHAT IS QUARK? Proton Neutron u u u d d d Charge + = 1 = 0 2 2 1 2 1 1 3 3 3 3 3 3 − − − 6 HISTORY OF QUARK MODEL In 1964: Murray Gell-Mann and George Zweig’s quark model • Independently worked in the same year • Murray Gell-Mann was awarded Nobel Prize for physics in 1969 but Zweig was only nominated once by Richard Feynman in 1977 but not received. Murray Gell-Mann visited CERN and ATLAS experiment George Zweig visited CERN and ALICE cavern 7 HISTORY OF QUARK MODEL In 1968: Discovery of up, down and strange quarks – Deep inelastic scattering experiments at SLAC (Stanford Linear Accelerator Center) in California – Accelerated electrons to nearly the speed of light hit the protons to find smaller particles inside them 8 HISTORY OF QUARK MODEL In 1974: Discovery of charm quark – Charmed particle that contains a charm quark, J/ψ meson was discovered by two teams SLAC and Brookhaven National Laboratory – This discovery finally convinced the physics community of the quark model’s validity (November Revolution) 9 HISTORY OF QUARK MODEL In 1977: Discovery of bottom quark – First described in 1973 by physicist Makoto Kobayashi and Toshihide Maskawa to explain CP violation – Discovered in 1977 by the Fermilab E288 experiment team 10 HISTORY OF QUARK MODEL In 1995: Discovery of top quark – The most massive of all observed quarks – Also postulated in 1973 by physicist Makoto Kobayashi and Toshihide Maskawa to explain CP violation - won the 2008 Nobel Prize in Physics for the prediction of top and bottom quark. 11 WORKS CITED • ”Fifty years of quarks” by Cian O’Luanaigh https://home.cern/about/updates/2014/01/fifty-years- quarks • “SLAC history” https://www6.slac.stanford.edu/about/slac-history 12 THANK YOU! 13.