Transverse-momentum and angular distributions of hadroproduced muon pairs

We study the angular distribution of muons in the dimuon rest frame from $\mathrm{pp}\to \mu \overline{\mu }X$ at high energy and large dimuon mass. Including smearing due to quark transverse momenta, we show that the Drell-Yan model predicts a polar angular distribution in the $t$-channel helicity frame of $1+\alpha {cos}^2\theta$ with $\alpha \gtrsim 0.8$. Experimental deviations from this prediction would cast serious doubt on the Drell-Yan picture.