Measurement of the weak mixing angle with the forward-backward asymmetry of Drell-Yan events at 8 TeV

We present a measurement of the effective weak mixing angle using the forward-backward asymmetry of Drell-Yan ($ee$ and $\mu\mu$) events in pp collisions at $\sqrt{s}=8~\mathrm{TeV}$ at CMS. The data sample corresponds to an integrated luminosity of $18.8~\mathrm{fb}^{-1}$ and $19.6~\mathrm{fb}^{-1}$ for muon and electron channels, respectively. The sample consists of 8.2 million dimuon and 4.9 million dielectron events. With new analysis techniques and a larger dataset, the statistical and systematic uncertainties are significantly reduced compared to our previous measurement. The extracted value of the effective weak mixing angle from the combined $ee$ and $\mu\mu$ data samples is $ \sin^2\theta^{\text{lept}}_{\text{eff}}=0.23101\pm 0.00036(\text{stat})\pm 0.00018(\text{syst})\pm 0.00016(\text{theory})\pm 0.00030(\text{pdf})$ or $ \sin^2\theta^{\text{lept}}_{\text{eff}}=0.23101\pm0.00052$.