Measurement of the Weak Mixing Angle and the Spin of the Gluon from Angular Distributions in the Reaction pp → Z/γ* + X → μ⁺μ^- + X with ATLAS

Abstract

The measurement of the effective weak mixing angle with the ATLAS experiment at the LHC is presented. It is extracted from the forward--backward asymmetry in the polar angle distribution of the muons originating from $Z$ boson decays in the reaction $pprightarrow Z/gamma^*+Xrightarrowmu^+mu^-+X$. In total $4.7,{rm fb}^{-1}$ of proton--proton collisions at $sqrt{s}=7,TeV$ are analysed. In addition, the full polar and azimuthal angular distributions are measured as a function of the transverse momentum of the $Z/gamma^*$ system and are compared to several simulations as well as recent results obtained in $pbar{p}$ collisions. Finally, the angular distributions are used to confirm the spin of the gluon using the Lam-Tung relation.