STOCKHOLM: Two Japanese citizens and a Japanese-born American were awarded the 2008 Nobel Prize in Physics for discoveries in the world of subatomic physics, the Royal Swedish Academy of Sciences announced Tuesday. An American, Yoichiro Nambu, 87, of the University of Chicago, won half of the prize for the discovery of a mechanism called spontaneous broken symmetry in subatomic physics. Makoto Kobayashi and Toshihide Maskawa of Japan shared the other half of the prize for discovering the origin of the broken symmetry that predicts the existence of at least three families of quarks in nature. "Spontaneous broken symmetry conceals nature's order under an apparently jumbled surface," the academy said in its citation. "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 Japanese-born Nambu moved to the United States in 1952 and is a professor at the University of Chicago, where he has worked for 40 years. He became a U.S. citizen in 1970. "As early as 1960, Yoichiro Nambu formulated his mathematical description of spontaneous broken symmetry in elementary particle physics," the citation said. Kobayashi and Maskawa "explained broken symmetry within the framework of the standard model but required that the model be extended to three families of quarks." Kobayashi, 64, works for the High Energy Accelerator Research Organization, or KEK, in Tsukuba, Japan. Maskawa, 68, is with the Yukawa Institute for Theoretical Physics at Kyoto University in Japan. "The spontaneous broken symmetries that Nambu studied differ from the broken symmetries described by Makoto Kobayashi and Toshihide Maskawa," the academy said. "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." The academy added that it was only in recent years that scientists have been able to confirm the explanations that Kobayashi and Maskawa proffered in 1972. "These predicted, hypothetical new quarks have recently appeared in physics experiments," the citation said. It added that two particle detectors BaBar at Stanford and at Tsukuba had detected broken symmetries independently of each other. "The results were exactly as Kobayashi and Maskawa had predicted almost three decades earlier," it said. The trio will share the 10 million kronor, or $1.4 million, purse; a diploma; and an invitation to the prize ceremonies in Stockholm on Dec. 10. Alfred Nobel, the Swede who invented dynamite, established the annual prizes in his will in the categories of medicine, physics, chemistry, literature and peace. The economics prize is technically not a Nobel but a 1968 creation, of Sweden's central bank.