First Measurement of the Angular Coefficients of Drell-Yan e⁺e⁻ pairs in the Z Mass Region from pbar{p} Collisions at sqrt{s} = 1.96 TeV

We report on the first measurement of the angular distributions of final state electrons in $p\bar{p}\to \gamma^{*}/Z\to e^{+}e^{-}+X$ events produced in the $Z$ boson mass region at $\sqrt{s}=1.96$ TeV. The data sample collected by the CDF II detector for this result corresponds to 2.1 fb$^{-1}$ of integrated luminosity. The angular distributions are studied as a function of the transverse momentum of the electron-positron pair and show good agreement with the Lam-Tung relation, consistent with a spin-1 description of the gluon, and demonstrate that at high values of the transverse momentum, $Z$ bosons are produced via quark anti-quark annihilation and quark-gluon Compton processes.