Wolf Prize Laureate in Physics 1994/5
Affiliation at the time of the award:
University of Chicago, USA
“for his contribution to elementary particle theory, including recognition of the role played by spontaneous symmetry-breaking in analogy with superconductivity theory, and the discovery of the color symmetry of the strong interactions”.
Professor Yoichiro Nambu originated several of the key ideas of elementary particle physics. He introduced the concept of spontaneous symmetry breaking, which appears in superconductivity theory, into elementary particle theory. By these means he explained, for instance, the low pion mass, the pion being the (nearly) massless excitation resulting from the breaking of chiral symmetry. Nambu introduced the notion of a SU(3) symmetry of the color quantum number, by which means he rid the original quark model of a crucial weakness. This symmetry, in its gauged version, is the foundation of the modern theory of the strong force. Nambu also originated the action for a relativistic string, a key ingredient in modern string theory. All these ideas were critical for the development of contemporary particle physic.