  The BaBar collaboration has measured the ratio
$R_{\tau\mu}^{\Upsilon(3S)}=\mathcal{B}(\Upsilon(3S)\rightarrow\tau^+\tau^-)/\mathcal{B}(\Upsilon(3S)\rightarrow\mu^+\mu^-)$
with a high level of precision. This measurement utilized a 28 fb$^{-1}$
dataset collected at a center-of-mass energy of 10.355 GeV. The measured ratio,
$R_{\tau\mu}^{\Upsilon(3S)}$, is measured to be
$R_{\tau\mu}^{\Upsilon(3S)}=0.966\pm0.008_{\textrm{stat}}\pm0.014_{\textrm{syst}}$.
This value is within 2 standard deviations of the standard model prediction
$R_{\tau\mu}^{\Upsilon(3S)}$=0.9948. The new measurement is approximately a
factor of 6$\times$ more precise than the only prior measurement. This
increased precision is in part due to a more complete analysis of the radiative
tail in the $\Upsilon(3S)$ decay, in addition to a significant increase in
statistics.
