US researcher Yoichiro Nambu and his Japanese colleagues Makoto Kobayashi and Toshihide Masukawa have won this year's Nobel Prize for Physics, the Royal Swedish Academy of Sciences announced in Stockholm on Tuesday.

Their discoveries were linked to describing the smallest building blocks in nature and nature's order, the academy said.

The academy cited Nambu of the Enrico Fermi Institute at the University of Chicago "for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics."

Kobayahsi and Maskawa were cited "for the discovery of the origin of broken symmetry which predicts the existence of at least three families of quarks in nature."

Naburu won half the award, worth 10 million kronor (1.5 million dollars), while Kobayashi and Maskawa share the other half.

Kobayashi is a retired professor with the High Energy Accelerator Research Organization (KEK) while Masukawa, also professor emritus, worked at Yukawa Institute for Theoretical Physics (YITP) at Kyoto University.