Aspects of Charmonium Physics

Abstract

I review possible resolution of the $J/\psi ({\psi }^{\prime })\to \rho -\pi$ puzzle based on two inputs: the relative phase between the one- photon and the gluonic decay amplitudes, and a possible hadronic excess in the inclusive nonelectromagnetic decay rate of ${\psi }^{\prime }$. The status of a universal large phase here is examined for its meaning and implications (including those for B-physics). Since the future of tau/charm facility(s) are again under consideration together with a future anti-proton facility at GSI, I propose to extend my review to include a broader discussion of charmonium physics. Outstanding questions like the status of the ${}^1{P}_1$ state of charmonium, measuring $D^0-{\bar{D}}^0$ mixing and relative strong phases, status of molecular P(S) - wave charmonia will also be discussed amongst others.

Comments: 7 pages, aipproc style file. Plenary session talk at Hadron 2001-Protvino