Recent Developments In Heavy Quarkonium Physics

Abstract

Recent developments in heavy quarknoium physics are reviewed in brief, including (i) nonrelativistic QCD(NRQCD), (ii) the importance of color-octet $(Q\bar{Q})$ components in the decay and the production of a physical heavy quarkonium state, (iii) limitation of the NRQCD factorization and (iv) the double humps in the $\ddot{I}€\ddot{I}€$ spectrum in the decay $\hat{I}\yen (3S)\to \hat{I}\yen (1S)\ddot{I}€\ddot{I}€$.

Talk given at PPPP workshop, Seoul, Korea (Oct. 31 -- Nov. 2, 1997)