Japanese physicists share Nobel Prize

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Japanese physicists share Nobel Prize
The Yomiuri Shimbun

Two Japanese particle physicists were awarded the 2008 Nobel Prize in Physics on Tuesday for discovering the origin of the broken symmetry that predicts the existence of at least three families of quarks in nature. They shared the prize with an American who discovered the mechanism of spontaneous broken symmetry in subatomic physics.

It is the first time Japanese scientists have shared the same prize.

The winners are Makoto Kobayashi, 64, executive director of the Japan Society for the Promotion of Science in Tokyo, and Toshihide Masukawa, 68, professor at Kyoto Sangyo University in Kyoto, and Yoichiro Nambu, 87, professor emeritus at the University of Chicago, who is a naturalized American.

In recent years, Hideki Shirakawa was awarded the 2000 Nobel Prize in Chemistry; Ryoji Noyori won the 2001 Nobel Prize in Chemistry; and Koichi Tanaka was awarded the 2002 Nobel Prize in Chemistry. The 2002 Nobel Prize in Physics was awarded to Masatoshi Koshiba.

The prize carries a monetary award of 10 million Swedish kronor (about 140 million yen). The awarding ceremony will be held in Stockholm on Dec. 10.

CP violation is phenomenon of violation of combined conservation laws associated with charge conjugation (C) and parity (P) by a weak nuclear force, which is responsible for reactions such as the decay of atomic nuclei.

The Kobayashi-Maskawa model (Masukawa's name is given without the "u" in the name of the model), which the two Japanese physicists published in 1973, posits certain quantum mechanical effects in the weak force between quarks as the cause of CP violation. They showed theoretically that the existence of at least six kinds of quarks could cause CP violation.

When they announced the model, only three quarks could be confirmed, but new quarks have been subsequently discovered as they predicted and the sixth quark was found in 1994 at the Fermi National Accelerator Laboratory in the United States, providing further evidence to support their theory.

Among many theories to prove CP violation, their model is considered the most reasonable and has become the basis for the standard theoretical explanation of the mechanism of elementary particles and thus the origin of universe.

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