Toshihide Maskawa
1940–2021, Nagoya, Japan, Kyoto, Japan
Japanese theoretical physicist, co-author of the CKM matrix — the theory requiring a third quark generation to explain CP violation in kaons.
Maskawa studied and earned his PhD at Nagoya University (1967), then joined Kyoto University's Yukawa Institute, where he spent most of his career and served as director.
In 1973, with Makoto Kobayashi, he built the 3×3 mixing matrix for three quark generations carrying a complex phase responsible for CP violation — famously he spoke no English at the time and the paper was written in English by Kobayashi. The predicted bottom and top quarks were confirmed; he received the 2008 Nobel, becoming the first laureate to deliver his Nobel lecture in Japanese.
Nobel-winning work
The 2×2 Cabibbo matrix mixed only the first two quark generations (u–c with d–s) via one real angle — no room for a complex phase, so kaon CP violation stayed unexplained. Kobayashi and Maskawa proved in 1973 that with three generations, the mixing matrix V_CKM has four independent parameters: three angles and one complex phase δ — and any nonzero δ makes CP violation 'built in' to the weak interaction.
The model precisely predicted the amount of CP violation in K and B mesons, B-meson lifetimes, and accounts for most lab-observed matter–antimatter differences — though not enough to explain the cosmic matter asymmetry. The 2008 Nobel was split: half to Nambu (spontaneous breaking), half to Kobayashi–Maskawa.
Workplaces: Kyoto University, Yukawa Institute for Theoretical Physics
Japan