Measurement of the $e^{+}{e}^{-}\to b\overline{b}$ Cross Section between $\sqrt{s}=10.54$ and 11.20 GeV

We report $e^{+}{e}^{-}\to b\overline{b}$ cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the SLAC PEP-II $e^{+}{e}^{-}$ collider. A total relative error of about 5% is reached in more than 300 center-of-mass energy steps, separated by about 5 MeV. These measurements can be used to derive precise information on the parameters of the ${\rm Y}(10860)$ and ${\rm Y}(11020)$ resonances. In particular we show that their widths may be smaller than previously measured.

Figure 1

Left: Measured $R_b$ as a function of $\sqrt{s}$ with the position of the opening thresholds of the $e^{+}{e}^{-}\to B_{(s)}^{(*)}{\overline{B}}_{(s)}^{(*)}$ processes indicated by dotted lines. Right: A zoom of the same plot with the result of the fit described in the text superimposed. The errors on data represent the statistical and the uncorrelated systematic errors added in quadrature.