1. INPC07, Yukawa Session, June 3, 2007 Interplay between Yukawa and Tomonaga in the Birth of Meson Toshimitsu Yamazaki, Nishina Memorial Foundation

2. BIRTH OF MESON Early history 1930’s H. Yukawa 1949 N. L. S. Tomonaga 1965 N. L. Interaction Interplay Y. Nishina (RIKEN) Father of Modern Science One of the discoverers of the muon in 1937

3. J (r) = A exp(- r) / r  = m U c / h Yukawa potential force range parameter mass of mediating particle U For instance, 1935

4. 1932 Discovery of the neutron (Chadwick) 1932 Heisenberg theory of nuclear structure 1933 spring meeting of JPMS (Sendai) both: 26 years old Yukawa (Kyoto --> Osaka): On the problem of nuclear electrons Nishina suggested a boson Bose electron? Tomonaga (RIKEN): On the proton-neutron interaction using J (r) = A exp(- r) / r nothing but Yukawa’s interaction !!!

5. Interplay between Yukawa and Tomonaga Letter from Tomonaga to Yukawa ~1933 Yukawa Archive at Yukawa Institute for Fundamental Physics, Kyoto

6. In fact, on the “ back of the envelope” Yukawa wrote down the electron Compton wavelength ~ 3 x 10 10 cm -1 !! Electron Compton wavelength ?  e = 260 !!, which would mean m U / m e = 260

7. Tomonaga used the form J(r) = A exp(- r)/r to account for the deuteron binding energy and p (n,  ) d reaction; yielding  6.5 x 10 12 /cm This letter must have affected Yukawa deeply, but, in the spring of 1933, neither of Yukawa and Tomonaga recognized the importance of the above formula and the implication of . Tomonaga published in 1936 Bethe-Peierls 1935 Tomonaga and Araki 1940 positive and negative meson capture to disentangle the problem of +/- pion/muon Fermi-Teller-Weisskopf 1947

8. Yukawa’s acknowledgement to Tomonaga Yukawa’s 1st paper in 1935

9. Yukawa’s struggling in 1933 how can a migrating real particle exist in nuclei? Bose electron ? force range ? p + e - = n ? Finally, in 1935, Yukawa arrived at virtual mediating particle a la K. Nishijima

10. The Yukawa theory A virtual particle mediates strong interaction m U /m e ~ 200 The mesons discovered Fundamental concept in physics Heitler-London- Heisenberg scheme: completely abandoned ?

11. Structure of K - pp Theoretical prediction Y. Akaishi, T.Y. Proc. Jpn. Acad. Ser. B 83 (2007) 144

12. Revival of the Heitler-London-Heisenberg scheme ! Cold Dense Nuclei - Kaon Condensation

13. Thank you very much