Weak mixing angle at low energies

We determine the weak mixing angle in the MS̄ scheme, sin²^θW(μ), at energy scales μ relevant for present and future low-energy electroweak measurements. We relate the renormalization group evolution of sin²^θW(μ) to the corresponding evolution of ^α(μ) and include higher-order terms in αₛ and α that had not been treated in previous analyses. We also update the analysis of nonperturbative, hadronic contributions and argue that the associated uncertainty is small compared to anticipated experimental errors. The resulting value of the low-energy MS̄ weak mixing angle is sin²^θW(0)=0.23867±0.00016.