Precision measurement of the $\mathcal{B}({\rm Y}(3S)\to {\tau }^{+}{\tau }^{-})/\mathcal{B}({\rm Y}(3S)\to {\mu }^{+}{\mu }^{-})$ ratio

J. P. Lees, V. Poireau, V. Tisserand +238

We report on a precision measurement of the ratio ${\mathcal{R}}_{\tau \mu }^{{\rm Y}(3S)}=\mathcal{B}({\rm Y}(3S)\to {\tau }^{+}{\tau }^{-})/\mathcal{B}({\rm Y}(3S)\to {\mu }^{+}{\mu }^{-})$ using data collected with the BaBar detector at the SL…