Yoshio Koide

Yoshio Koide (小出 義夫, Koide Yoshio, born May 16, 1942 in Kanazawa, Ishikawa) is a Japanese theoretical physicist working in particle physics. Koide is famous for his eponymous Koide formula, which some physicists think has great importance while other physicists contend that the formula is merely a numerical coincidence.

Early life and education

Koide earned in 1967 a B.Sc. with major in physics and in 1967 a M.Sc. in Theoretical Elementary Particle Physics from Kanazawa University. In 1970, he received his Doctor of Science degree from Hiroshima University with a thesis “On the Two-Body Bound State Problem of Dirac Particles”.[1]

Career

After working as a postdoc in the physics department of Hiroshima University and then a postdoc in the applied mathematics department of Osaka University, he became, from 1972 to 1973, a Lecturer in the School of Science and Engineering, Kinki University, Osaka. Koide was Assistant Professor (1973-1977) then Associate Professor (1977-1987) of General Education, Shizuoka Women's University, Shizuoka. From April 1987 to March 2007 he was a Professor of Physics at University of Shizuoka, Shizuoka and then retired as professor emeritus. In 1986 he was a visiting professor at the University of Maryland and in 2002 a visiting researcher at CERN. Koide was from April 2007 to March 2009, a guest professor at Research Institute for Higher Education and Practice, Osaka University, then from April 2009 to March 2011 a guest professor and from April 2011 a guest researcher at Osaka University, and from April 2010 a professor, Department of Maskawa Institute, Kyoto Sangyo University, Kyoto.

Contributions to physics

In the composite model of mesons, Koide's thesis demonstrated that a mass of a composite particle which consists of the rest masses cannot be lighter than except for the case when JP is not = 0-. This offered a severe problem for the quark model. (Koide’s work was done before the establishment of QCD.)[1]

Katuya and Koide predicted that lifetimes of D± and D0 should be considerably different from what was at that time the conventional anticipation tau(D±)= tau(D0). Their prediction of these lifetimes was the first in the world prior to the experimental observation.[2]

He published the famous Koide formula in 1982[3] with a different presentation in 1983.[4]

Originally, Koide's proposed charged lepton mass formula was based on a composite model of quarks and leptons. In a 1990 paper, from the standpoint that the charged leptons are elementary, by introducing a scalar boson with (octet + singlet) of a family symmetry U(3), Koide re-derived the charged lepton mass formula from minimizing conditions for the scalar potential.[5]

In 2009, he related the neutrino mixing matrix to the up-quark mass matrix.[6] Koide and Hiroyuki Nishiura have published articles on a quark and lepton mass matrix model[7][8] and a neutrino mass matrix model.[9]

References
  1. Koide, Y. (1968). "On the Two-Body Bound State Problem of Dirac Particles". Progress of Theoretical Physics. 39 (3): 817–829. Bibcode:1968PThPh..39..817K. doi:10.1143/PTP.39.817.
  2. Katuya, M.; Koide, Y. (1979). "Is the 20-dominance model valid in charm decays, too?". Physical Review D. 19 (9): 2631–2634. Bibcode:1979PhRvD..19.2631K. doi:10.1103/PhysRevD.19.2631.
  3. Koide, Y. (1982). "Fermion-boson two-body model of quarks and leptons and cabibbo mixing". Lettere al Nuovo Cimento. 34 (8): 201–205. doi:10.1007/BF02817096. S2CID 120885232.
  4. Y. Koide (1983). "A fermion-boson composite model of quarks and leptons". Physics Letters B. 120 (1–3): 161–165. Bibcode:1983PhLB..120..161K. doi:10.1016/0370-2693(83)90644-5.
  5. Koide, Y. (1990). "Charged Lepton Mass Sum Rule from U(3)-FAMILY Higgs Potential Model". Modern Physics Letters A. 5 (28): 2319–2323. Bibcode:1990MPLA....5.2319K. doi:10.1142/S0217732390002663.
  6. Koide, Y. (2009). "Yukawaon model in the quark sector and nearly tribimaximal neutrino mixing". Physics Letters B. 680 (1): 76–80. arXiv:0904.1644. Bibcode:2009PhLB..680...76K. doi:10.1016/j.physletb.2009.08.038. S2CID 525463.
  7. Koide, Y.; Nishiura, H. (2017). "Flavon VEV scales in U(3)×U(3)′ model". International Journal of Modern Physics A. 32 (15). arXiv:1701.06287. Bibcode:2017IJMPA..3250085K. doi:10.1142/S0217751X17500853. S2CID 119096804.
  8. Koide, Y.; Nishiura, H. (2018). "Parameter-independent quark mass relation in the U(3) × U(3)′ model". Modern Physics Letters A. 33 (39). arXiv:1805.07334. Bibcode:2018MPLA...3350230K. doi:10.1142/S0217732318502309. S2CID 119079768.
  9. Koide, Y.; Nishiura, H. (2019). "Neutrino Mass Matrix Model with Only Three Adjustable Parameters". arXiv:1911.03411 [hep-ph].
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