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 known for his eponymous Koide formula, which some physicists think has great importance but which other physicists contend 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 ${\displaystyle m}$ of a composite particle which consists of the rest masses ${\displaystyle m_{1},m_{2}}$ cannot be lighter than ${\displaystyle {\frac {1}{2}}(m_{1}+m_{2})}$ except for the case ${\displaystyle m_{1}=m_{2}}$ when J^P 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 D^0 should be considerably different from what was at that time the conventional anticipation tau(D^±)= tau(D^0). 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].

External links

• Koide's web site (in Japanese)
• physics papers by Y. Koide available on arxiv.org
• Scientific publications of Yoshio Koide on INSPIRE-HEP