Makoto Kobayashi
active c. 1944, Nagoya, Japan
Japanese theoretical physicist, co-author of the CKM matrix predicting a third quark generation to explain CP violation.
Kobayashi earned his PhD at Nagoya University in 1972, then worked at Kyoto University before moving to KEK in Tsukuba, where he became professor emeritus.
In 1973, with Toshihide Maskawa, he showed that CP violation — a phenomenon Nicola Cabibbo could not explain — arises naturally if six quarks exist instead of four. The Kobayashi–Maskawa matrix with its irreducible complex phase became a pillar of the Standard Model; the bottom (1977) and top (1995) quarks confirmed the prediction. He shared the 2008 Nobel Prize.
Nobel-winning work
CP violation — the universe treating particles and antiparticles differently — was discovered by Cronin and Fitch in kaon decay in 1964, but with only four quarks (u, d, s, c), theory offered no way to put a complex phase into the quark-mixing matrix: CP violation was inexplicable in that framework.
In 1973, Kobayashi and Maskawa realized that with three quark generations, the extended Cabibbo matrix becomes a 3×3 matrix carrying an irremovable complex phase — the Standard Model's only natural source of CP violation. Predicting two new quarks (bottom, top) was bold but correct: the B-factories at KEK (Belle) and SLAC (BaBar) later measured CKM phases matching CP violation in B mesons. The 2008 Nobel cited 'the discovery of the origin of broken symmetry predicting the existence of at least three families of quarks'.
Workplaces: KEK (High Energy Accelerator Research Organization), Kyoto University
Japan