Updated description of quarkonium by power-law potentials

The spectra and decay rates of charmonium ($c\overline{c}$) and bottomonium ($b\overline{b}$) levels are well described, for the most part, by a power-law potential $V\left(r\right)=\frac{\lambda (r^{\alpha }-1)}{\alpha }+\mathrm{const}$, where $\alpha \simeq 0$. The results of an up-to-date fit to the data on spin-averaged levels are presented. A fit to levels alone favors $\alpha =-0.045\mathrm{}$ and gives very little preference for quark masses, while inclusion of leptonic width data leads to $\alpha =-0.14\mathrm{}$ and a $b$-quark mass in the vicinity of 5 GeV. A fit to the known electric dipole transitions in $b\overline{b}$ systems favors a slightly smaller $b$-quark mass, but with large errors.