Lev Borisovich Okun (born 7.07.1929) is a Soviet theoretical physicist and a corresponding member of the USSR Academy of Sciences (1966). He was born in Sukhinichi, Kaluga Region. He graduated from the Moscow Engineering Physics Institute (1953). Since 1954 he has worked at the Institute of Theoretical and Experimental Physics.
His research was in the theory of elementary particles. Together with I. Ya. Pomeranchuk he predicted (1956) the equality of the cross sections, at high energies, of particles belonging to a given isotopic multiplet. He predicted (1957) the isotopic properties of weak hadronic currents and the existence of a nonet of pseudoscalar mesons.
Together with others he considered (1957) the consequences of the violation of P, C and CP invariance, proposed (1974) a theory of the unstable vacuum, and constructed (1976) quantum-chromodynamic sum rules for charmonium.