Status of Chiral Belle: The Beam Polarization Upgrade of SuperKEKB

Recent work associated with upgrading the SuperKEKB $e^+e^-$ collider with polarized electron beams and Chiral Belle’s program of unique precision measurements using Belle II will be described. These include five values of $\sin^2\theta_W$ via left-right asymmetry measurements ($A_{LR}$) in $e^+e^- \rightarrow e^+e^-, \mu^+\mu^-, \tau^+\tau^-, c\bar{c},b\bar{b}$. $A_{LR}$ yields values of the neutral current (NC) coupling constant of each fermion species that will match (e,$\tau$) or greatly exceed (b, c, $\mu$) existing $Z^0$ world averages precision, but at 10GeV, thereby providing unique probes the running of $\theta_W$. The program also probes new physics via the highest precision measurements by many factors of NC universality and tau lepton properties, including the tau g-2. After providing an update on Chiral Belle's physics potential, we will report on recent R\&D related to provision of the required hardware, including modest upgrades to the SuperKEKB electron ring.