Possible effects of color screening and large string tension in heavy quarkonium spectrum

Possible effects of the color screened confinement potential are investigated. Color screened linear potential with a large string tension $T=(0.26-0.32)GeV^2$ is suggested by a study of the $c\bar c$ and $b\bar b$ spectra. The $\psi (4160)$ and $\psi (4415)$ are respectively assigned as the $\psi (4S)$-dominated and the $\psi (5S)$ $c\bar c$ states. Satisfactory results for the masses and leptonic widths (with QCD radiative corrections) of $c\bar c$ and $b\bar b$ states are obtained.