Bunji Sakita, a physicist par excellence

Professor Bunji Sakita, Distinguished Professor of Physics at the City College of New York, passed away on August 31, 2002 in Japan after a year-long battle with cancer.

Bunji Sakita was born in Japan in 1930 in the Toyama prefecture and received his bachelor's degree from Kanazawa University in 1953. He then worked with Sakata's group in Nagoya University, obtaining his master's degree in 1956. He was among a select group of Japanese students recruited by Robert Marshak to come for graduate studies to the University of Rochester. In Rochester, Sakita worked with Professor Charles Goebel and received his doctorate in 1959. He went onto a postdoctoral position and a professorship at the University of Wisconsin. In his beginning years at Wisconsin, and during a year he spent at the Argonne National Laboratory, he developed the SU(6) symmetry of the nonrelativistic quark model generalizing Wigner's supermultiplet symmetry of combining spin and isospin.

In 1967, during a visit to Israel, he learned of the dual resonance model and his later work at Wisconsin was mostly devoted to this idea. With Goebel, he obtained the many-particle generalization of the Veneziano amplitude. In work with K. Kikkawa, M.A. Virasoro and others, he addressed the problem of unitarity of the dual amplitudes, setting up the formalism of dual diagrams, analogous to Feynman diagrams, for the computation of loop amplitudes. In work done with C.S. Hsue, M.A. Virasoro and notably with J.L. Gervais, Sakita developed the functional formalism for these calculations in which summation over Riemann surfaces naturally emerged.

In 1971, Gervais and Sakita, in a paper titled `Field Theory Interpretation of Supergauges in Dual Models', showed the boson-fermion symmetry of the fermionic string theory, writing down the first linear supersymmetric action. In modern parlance the Gervais-Sakita lagrangian has a local superconformal symmetry. The 1973 work of Wess and Zumino extended the two-dimensional supersymmetry discovered in string theory to four dimensional field theories with spacetime supersymmetry. (Different versions of supersymmetry had been discovered in the Soviet Union a little earlier; this was not known to physicists elsewhere at that time.)

In Sakita's papers from this time, we find the beginnings of the modern formulation of string perturbation theory as sums over Riemann surfaces as well as the seeds of supersymmetry and conformal field theory, two of the other key ideas of string theory.

In 1970, when Robert Marshak became president of the City College of NY, Sakita moved there as Distinguished Professor to participate in the rapid expansion of the physics program and to lead the High Energy Group. A strong group was built up with first rate work on many areas, string theory, supersymmetry, field theory and particle phenomenology, to name a few.

From his days as a student Sakita was deeply influenced by the method of collective variables in many body theory. The theme of collective motions continued throughout his career. In the early years at City College he worked on collective dynamics in the strong coupling theory of meson-nucleon physics in the path integral approach. Subsequently with Gervais and with his student A. Jevicki, Sakita wrote a number of papers giving a firm foundation to the formalism of collective coordinates associated with symmetries, which was then applied to the quantum theory of solitons and instantons and to quark confinement and baryons in Quantum Chromodynamics. The theme of collective motions is also present in his work, with A. Jevicki, on the collective field method applied to the large N limit of matrix models (where it has become part of the standard lore) and in his work on condensed matter systems like charge density waves and the Hall effect. He worked on the latter class of problems till the last days of his life.

Sakita was an exceptional mentor with an intense working relationship with many of his students and postdocs whom he treated as his equals. Many of the CCNY students and research associates of this time have gone onto distinguished careers of their own.

In recognition of his many contributions, he was the recipient of a Guggenheim Fellowship in 1970 and was awarded the Nishina Memorial Prize of Japan in 1974.

Sakita's interests were broad and varied, always seeking out the fundamental physical basis of any problem. He also had a large number of collaborators and students spread all over the globe, in the United States, France, Italy, Japan, India and Chile, to mention a few. He had a true measure of himself, both as a person and as a physicist, which translated into a sense of humility and generosity and an unobtrusive, yet direct, way of speaking. His opinion, on matters of physics and nonphysics, was valued by all; he will be sorely missed.