Yoichiro Nambu of the Enrico Fermi Institute at University of Chicago was selected for "the discovery of the mechanism of spontaneous broken symmetry in subatomic physics," the Royal Swedish Academy of Sciences said in a news release issued by the Nobel Foundation.

Makoto Kobayashi, of the High Energy Accelerator Research Organization in Tsukuba, Japan, and Toshihide Maskawa, from the Yukawa Institute for Theoretical Physics at Kyoto University, were recognized for their discovery of "the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature," the foundation said.

Nambu's mathematical description of spontaneous broken symmetry in elementary particle physics and helped develop the Standard Model of particle physics, the foundation said. The model unified the smallest building blocks of matter and three of nature's four forces in one theory.

Kobayashi and Maskawa found a different set of broken symmetries, suggesting spontaneous occurrences existed in nature since the universe began. The pair explained broken symmetry within the Standard Model framework but required that the model extend to three families of quarks.

Nambu will receive half of the $1.4 million prize, with Kobayashi and Maskawa splitting the other half.