Determination of the ?(1S) leptonic width

Analyzing the data recorded with the MD-1 detector operated at the VEPP-4 storage ring we have determined the ϒ(1S) resonance leptonic partial width and mass. We find $$\begin{gathered} \Gamma _{ee} = 1.29 \pm 0.03 \pm 0.03keV, \hfill \\ M = 9460.59 \pm 0.09 \pm 0.05MeV/c^2 \hfill \\ \end{gathered} $$ M=9460.59±0.09±0.05 MeV/c2. This new value of the ϒ(1S) mass should supersede the previously published value [11] based on almost the same statistics.