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

TL;DR

This paper reports a highly precise measurement of the effective weak mixing angle using proton-antiproton collision data from the Fermilab Tevatron, combining muon and electron decay channels for the first time at a hadron collider.

Contribution

It provides the most precise single-experiment measurement of the weak mixing angle at a hadron collider, combining muon and electron channels for improved accuracy.

Findings

Measured $ ext{sin}^2 heta_ ext{eff}^{ ext{lept}}$ in muon channel: 0.23016 ± 0.00064.

Combined result with electron channel: 0.23095 ± 0.00040.

Most precise measurement from a single hadron collider experiment.

Abstract

We present a measurement of the effective weak mixing angle parameter $\sin^2\theta_\text{eff}^{\ell}$, 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 $\sin^2\theta_\text{eff}^{\ell}[\mu\mu]=0.23016 \pm 0.00064$ is further combined with the result from the D0 measurement in $p\bar{p}\rightarrow Z/\gamma^{*}\rightarrow e^{+} e^{-}$ events, resulting in $\sin^2\theta_\text{eff}^{\ell} [\text{comb.}]=0.23095 \pm 0.00040$. 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 $Z/\gamma^*$ to light quarks.