MASKAWA, TOSHIHIDE / Physics / Researchers

International Center for Scientific Research




Former director and professor emeritus at the Yukawa Institute for Theoretical Physics (YITP), Kyoto University, Kyoto, Japan.

Research interests

The fact that our world does not behave perfectly symmetrically is due to deviations from symmetry at the microscopic level.

As early as 1960, Yoichiro Nambu formulated his mathematical description of spontaneous broken symmetry in elementary particle physics. Spontaneous broken symmetry conceals nature’s order under an apparently jumbled surface. It has proved to be extremely useful, and Nambu’s theories permeate the Standard Model of elementary particle physics. The Model unifies the smallest building blocks of all matter and three of nature’s four forces in one single theory.

The spontaneous broken symmetries that Nambu studied, differ from the broken symmetries described by Makoto Kobayashi and Toshihide Maskawa. These spontaneous occurrences seem to have existed in nature since the very beginning of the universe and came as a complete surprise when they first appeared in particle experiments in 1964. It is only in recent years that scientists have come to fully confirm the explanations that Kobayashi and Maskawa made in 1972. It is for this work that they are now awarded the Nobel Prize in Physics. They explained broken symmetry within the framework of the Standard Model, but required that the Model be extended to three families of quarks. These predicted, hypothetical new quarks have recently appeared in physics experiments. As late as 2001, the two particle detectors BaBar at Stanford, USA and Belle at Tsukuba, Japan, both detected broken symmetries independently of each other. The results were exactly as Kobayashi and Maskawa had predicted almost three decades earlier.

Prizes and awards

2008 Nobel Physics Prize, with Makoto Kobayashi and Yoichiro Nambu, for discovering the origin of the broken symmetry that predicts the existence of at least three families of quarks in nature.


CP Violation in the Renormalizable Theory of Weak Interaction. By Makoto Kobayashi, Toshihide Maskawa (Kyoto U.).
Published in:Prog.Theor.Phys.49:652-657,1973

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