Yoichiro Nambu (born 18.01.1921) is a Japanese theoretical physicist. He was born in Tokyo. He graduated from the University of Tokyo (1942). In 1945 — 49 he worked there, in 1949 —71 he was professor at the university in Osaka, and from 1971 he has been professor at the E. Fermi Institute for Nuclear Studies of the University of Chicago. His research was in quantum electrodynamics, scattering theory, elementary particle physics, quantum field theory, the statistics of crystals and the theory of superconductivity. Independently of others he put forward (1951) the idea of associated production of strange particles, predicted the isoscalar vector meson, the ω meson (1957), introduced the relation called “crossing symmetry” (1957), gave a general mathematical proof of Goldstone's theorem (1964), put forward the idea of symmetry breaking (1960), introduced (1964 — 65) a new quantum number, colour, and together with M. Han constructed (1965) a scheme of strong interactions based on three triplets of quarks with integer charges (the Han — Nambu model). Within this model he introduced (1966) the colour interaction and initiated quantum chromodynamics. In 1961 he applied the concept of pairing to the problem of the mass spectrum of elementary particles. He put forward (1960) the hypothesis of partial conservation of the weak axial current of hadrons. A member of the National Academy of Sciences of the USA (1973) and of the American Academy of Arts and Sciences. The D. Heineman (1970) and R. Oppenheimer (1976) prizes and others.