Measurement of the Effective Weak Mixing Angle in $p\bar{p}\to Z\mathrm{/}{\gamma }^{\ast }\to {\mathrm{\ell }}^{+}{\mathrm{\ell }}^{-}$ Events

We present a measurement of the effective weak mixing angle parameter ${\sin }^2{\theta }_{\text{eff}}^{\mathrm{\ell }}$, in $p\bar{p}\rightarrow Z/\gamma^* \rightarrow \mu^+\mu^-$ events at a center of mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider and corresponding to 8.6 fb${}^{-1}$ of integrated luminosity. The measured value of ${\sin }^2{\theta }_{\text{eff}}^{\mathrm{\ell }}[\mu \mu ]=0.23016\pm 0.00064$ is further combined with the result from the D0 measurement in $p\bar{p}\rightarrow Z/\gamma^{*}\rightarrow e^{+} e^{-}$events,resultingin$\sin^2\theta_$\text{eff}$^{\ell} [$\text{comb.}$]=0.23095 \pm 0.00040$. This combined result is the most precise measurement from a single experiment at a hadron collider and is the most precise determination using the coupling of the $Z\mathrm{/}{\gamma }^{\ast }$ to light quarks.