Yoichiro Nambu, Enrico Fermi Institute for Nuclear Studies, Chicago, USA
for being one of the first physicists to formulate the idea of spontaneous symmetry breaking and in particular, chiral symmetry breaking in relativistic particle physics. His contributions to the quark model in the sixties and, later, his geometrical formulation of the dual resonance models as the dynamics of a relativistic string are of fundamental importance. The scope and intensity of current research in string are of fundamental importance. The scope and intensity of current research in string theory are witness to the profundity of Nambu's contributions to particle physics.
Alexander Polyakov, Landau Institute of Theoretical Physics, Moscow, Russian Federation (at the time of the award)
for being among the first to emphasize the importance of scale invariance in quantum field theory, particularly in connection with the theory of critical phenomena. He was also one of the first to recognize the relevance of the topological ideas in field theory, through the discovery of the monopole and instanton solutions in non-Abelian Yang-Mills theories. Polyakov's reformulation of the string theories in terms of covariant path integral and his classification of the 2-dimensional conformal field theories (in collaboration with his colleagues at the Landau Institute) are among the important contributions to theoretical physics of this decade.