First Measurement of the Angular Coefficients of Drell-Yan<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math>Pairs in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Z</mml:mi></mml:math>Mass Region from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mover accent="true"><mml:mi>p</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math>Collisions at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>1.96</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>TeV</mml:mi></mml:math>

We report on the first measurement of the angular distributions of final state electrons in $p\overline{p}\ensuremath{\rightarrow}{\ensuremath{\gamma}}^{*}/Z\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}+X$ events produced in the $Z$ boson mass region at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. The data sample collected by the CDF II detector for this result corresponds to $2.1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ 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-antiquark annihilation and quark-gluon Compton processes.