First measurement of the $Z\rightarrow \mu^+ \mu^-$ angular coefficients in the forward region of $pp$ collisions at $\sqrt{s}=13$ TeV

TL;DR

This paper presents the first measurement of angular coefficients of Z boson decay into muons in the forward region at 13 TeV, providing new insights into proton structure and testing theoretical models.

Contribution

It introduces the first measurement of Z boson angular coefficients in the forward region at 13 TeV, expanding understanding of Drell-Yan processes and parton distributions.

Findings

Measured angular coefficients as functions of muon transverse momentum and rapidity.

Compared results with various theoretical predictions, finding general agreement.

Provides data to improve models of proton structure and Z boson production.

Abstract

The first study of the angular distribution of $\mu^+ \mu^-$ pairs produced in the forward rapidity region via the Drell-Yan reaction $pp \rightarrow \gamma^{*}/Z +X \rightarrow l^+ l^- + X$ is presented, using data collected with the LHCb detector at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.1 $\rm{fb}^{-1}$. The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the $Z$-boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton.