Measurement of the forward Z boson production cross-section in pp collisions at $\sqrt{s} = 13$ TeV

TL;DR

This paper reports a precise measurement of the Z boson production cross-section in proton-proton collisions at 13 TeV using LHCb data, including differential distributions, to test Standard Model predictions.

Contribution

First measurement of Z boson production cross-section at 13 TeV in the forward region with detailed differential distributions using LHCb data.

Findings

Integrated cross-section: 194.3 pb with uncertainties.

Differential cross-sections as functions of rapidity, pT, and angular variables.

Results consistent with Standard Model predictions.

Abstract

A measurement of the production cross-section of Z bosons in pp collisions at $\sqrt{s} = 13$ TeV is presented using dimuon and dielectron final states in LHCb data. The cross-section is measured for leptons with pseudorapidities in the range $2.0 < \eta < 4.5$, transverse momenta $p_\text{T} > 20$ GeV and dilepton invariant mass in the range $60<m(\ell\ell)<120$ GeV. The integrated cross-section from averaging the two final states is \begin{equation*}\sigma_{\text{Z}}^{\ell\ell} = 194.3 \pm 0.9 \pm 3.3 \pm 7.6\text{ pb,}\end{equation*} where the first uncertainty is statistical, the second is due to systematic effects, and the third is due to the luminosity determination. In addition, differential cross-sections are measured as functions of the Z boson rapidity, transverse momentum and the angular variable $\phi^*_\eta$.