Comparing theoretical descriptions of Drell-Yan angular coefficients

Abstract

A quantitative comparison of the predictions of three theoretical descriptions (TMD, pQCD and geometrical) of the angular coefficients in Drell-Yan Z-boson production with new experimental data on angular coefficients obtained by the ATLAS, CMS and LHCb collaborations has been performed. In the central rapidity region at low-$Q_T$, the TMD calculation provides a better description of the $A_0$ and $A_2$ coefficients among the descriptions considered. The differences between the approaches are less pronounced for $A_1$,$A_3$ and $A_4$ coefficients. The results identify $A_0$,$A_2$ and the Lam--Tung relation as the most sensitive observables at low-QT and illustrate the domains of applicability of the three descriptions.