Dependencies of Lepton Angular Distribution Coefficients on the Transverse Momentum and Rapidity of$Z$ Bosons Produced in $pp$ Collisions at LHC

TL;DR

This paper analyzes how lepton angular distribution coefficients in Z boson production depend on transverse momentum and rapidity in proton-proton collisions at the LHC, revealing strong dependencies that can be explained geometrically.

Contribution

It provides a detailed study of the dependencies of angular distribution coefficients on kinematic variables, supported by a geometric interpretation, enhancing understanding of Z boson production dynamics.

Findings

Strong transverse momentum dependence of angular coefficients

Significant rapidity dependence for some coefficients

Weak rapidity dependence for others

Abstract

High precision data of lepton angular distributions for $\gamma^*/Z$ production in $pp$ collisions at the LHC, covering broad ranges of dilepton transverse momenta ($q_T$) and rapidity ($y$), were recently reported. Strong $q_T$ dependencies were observed for several angular distribution coefficients, $A_i$, including $A_0 - A_4$. Significant $y$ dependencies were also found for the coefficients $A_1$, $A_3$ and $A_4$, while $A_0$ and $A_2$ exhibit very weak rapidity dependence. Using an intuitive geometric picture we show that the $q_T$ and $y$ dependencies of the angular distributions coefficients can be well described.