A Japanese American theorist whose work helped explain how the cosmos came into being and two Japanese theorists who predicted the existence of a family of exotic particles called quarks will share the 2008 Nobel Prize in Physics, the Swedish Nobel Foundation announced yesterday.

All three studied a curious but essential phenomenon known as broken symmetry, which helps to explain the behavior of matter on the smallest scale, where the everyday laws of physics seemingly break down or are ignored.

Yoichiro Nambu, 87, a Tokyo-born physicist at the University of Chicago's Enrico Fermi Institute, will receive half the $1.4 million prize for his mathematical description of "spontaneous broken symmetry," which played a major role in development of the Standard Model of particle physics, which integrates elementary particles and the strong, weak and electromagnetic forces of nature.

Makoto Kobayashi, 64, a researcher at the High Energy Accelerator Research Organization, or KEK, in Tsukuba, Japan, and Toshihide Maskawa, 68, of Kyoto University's Yukawa Institute for Theoretical Physics, will share the other half of the award for their explanation of why the breakdown of elementary particles called kaons and B-mesons is not symmetrical, as scientists had once thought it should be.

Dr. Nambu said he was surprised and honored when he received news of the award yesterday. "I didn't expect it. I've been told for many years that I was on the list" to receive the award, he told The Associated Press. "I had almost given up."

At a news conference in Tsukuba, Dr. Kobayashi said he also was not expecting the award. "I've only been pursuing my interest. ... It's an honor to receive the prize for my work from long ago. I wrote that paper more than 30 years ago."

But at a separate news conference in Kyoto, Dr. Maskawa said he saw it coming. "There is a pattern to how the Nobel Prize is awarded," he said. "I did not think I would get the award up until last year, but I predicted it pretty much this year."