Definition
Susumu Okubo (Japanese: 岡部 進) was a Japanese theoretical physicist noted for his contributions to particle physics, particularly the development of symmetries in hadron spectroscopy and the formulation of the Okubo–Zweig–Iizuka (OZI) rule.
Overview
Born in 1935 in Japan, Okubo pursued his higher education in physics, obtaining a doctorate in the field of theoretical particle physics. He held academic positions at several Japanese universities, including the University of Tokyo and Osaka University, where he conducted research on the classification of subatomic particles and the underlying symmetries of the strong interaction. His most influential work involved extending the SU(3) flavor symmetry framework introduced by Murray Gell‑Mann and Yuval Ne'eman, leading to refined mass formulas for mesons and baryons. In collaboration with George Zweig and Jugoro Iizuka, Okubo helped articulate the OZI rule, an empirical observation that explains the suppression of certain decay processes in hadronic physics.
Okubo’s research contributed to the broader acceptance of quark models and the development of quantum chromodynamics (QCD) as the theory of the strong force. He published numerous papers in peer‑reviewed journals and was recognized with several national scientific awards in Japan.
Accurate information regarding the exact date of his death is not confirmed; sources indicate he passed away in the early 2020s.
Etymology/Origin
The name “Susumu” (進) is a common Japanese given name meaning “to advance” or “to progress.” The surname “Okubo” (岡部) combines the characters “oka” (hill) and “bu” (section or part), a typical Japanese family name.
Characteristics
- Field of Study: Theoretical particle physics, particularly symmetry principles in hadron classification.
- Key Contributions:
- Gell‑Mann–Okubo Mass Formula: An extension of SU(3) symmetry that provides relations among the masses of meson and baryon multiplets.
- Okubo–Zweig–Iizuka (OZI) Rule: A phenomenological rule describing the suppression of processes that require disconnected quark line diagrams, influencing the understanding of hadronic decay patterns.
- Methodology: Employed group‑theoretical techniques, especially Lie algebras and representation theory, to derive mass relations and selection rules.
- Publications: Authored influential papers such as “On the mass formula of the baryon octet” (1962) and “Elementary particle physics—A review of the OZI rule” (1975).
Related Topics
- SU(3) Flavor Symmetry – The mathematical framework underlying the classification of hadrons that Okubo helped extend.
- Gell‑Mann–Okubo Mass Formula – A specific mass relation for members of meson and baryon octets.
- Okubo–Zweig–Iizuka (OZI) Rule – A selection rule in strong interaction processes, co‑formulated by Okubo.
- Quark Model – The paradigm for describing subatomic particles as combinations of quarks, to which Okubo’s work provided supporting theoretical structure.
- Quantum Chromodynamics (QCD) – The modern theory of the strong force, which incorporates the symmetry principles explored by Okubo.