Speaker
Description
Belle II is considering upgrading SuperKEKB with a polarized electron beam. The introduction of beam polarization to the experiment would significantly expand the physics program of Belle II in the electroweak, dark , and lepton flavor universality sectors. For all of these future measurements a robust method of determining the average beam polarization is required to maximize the level of precision. The $BABAR$ experiment has developed a new beam polarimetry technique, Tau Polarimetry, capable of measuring the average beam polarization to better than half a percent. Tau Polarimetry strongly motivates the addition of beam polarization to SuperKEKB and could also be used at future $e^+e^-$ colliders such as the ILC. We present the performances of this method through an analysis of the full data set of about 470 $\text{fb}^{-1}$ collected at the $e^+e^-$ PEP-II collider by the $BABAR$ detector.
