Bottomonium Spectrum with Screened Potential

Abstract

As a sister work of Ref.[1], we incorporate the color-screening effect due to light quark pair creation into the heavy quark-antiquark potential, and investigate the effects of screened potential on the spectrum of bottomonium. We calculate the masses, electromagnetic decays, and E1 transitions of bottomonium states. We find that the fine splittings between $\chi_{bJ}$ (J=0,1,2) states are in good agreement with experimental data, and the E1 transition rates of $\Upsilon(2S)\to\gamma\chi_{bJ}(1P)$ and $\Upsilon(3S)\to\gamma\chi_{bJ}(2P)$ (J=0,1,2) all agree with data within experimental errors. In particular, the mass of $\Upsilon(6S)$ is lowered down to match that of the $\Upsilon(11020)$, which is smaller than the predictions of the linear potential models by more than 100 MeV. Comparison between charmonium and bottomonium in some related problems is also discussed.