Chen Ning Yang (born 22.09.1922) is an American theoretical physicist and a member of the National Academy of Sciences (1965). He was born in Hofei (China). He graduated from the National University (1942). In 1948 he received the degree of Doctor of Philosophy at the University of Chicago, where he worked in 1948-49. In 1949-65 he was at the Institute for Advanced Study in Princeton (professor from 1955). From 1966 he has been professor at New York University and director of the Institute of Theoretical Physics.
His work was on statistical mechanics, quantum field theory and elementary particle physics. In 1954, together with R. Mills, he proposed the gauge principle and developed the theory of the vector meson field (the Yang — Mills theory), laying the foundations of the theory of vector, or compensating, fields (the Yang — Mills compensating fields). In 1956, together with T. D. Lee, he postulated that the law of conservation of parity is violated in weak interactions (Nobel Prize, 1957), and in 1957 (together with T. D. Lee and R. Oehme) that in beta decay not only parity but also charge conjugation is not conserved. In the same year, independently of L. D. Landau and A. Salam, he and T. D. Lee put forward the hypothesis that combined parity (CP symmetry) is conserved in weak interactions. His research also concerned the structure and systematics of elementary particles and collisions of high-energy particles. Together with E. Fermi he proposed (1949) the first composite model of an elementary particle, assuming that the pion is a system consisting of a nucleon and an antinucleon (the Fermi — Yang model). In 1960, together with T. D. Lee, he put forward the hypothesis that weak interactions are carried by an intermediate vector boson.
The A. Einstein Award (1957).