Measurement of the underlying event activity in inclusive Z boson production in proton-proton collisions at $\sqrt{s} = $ 13 TeV

TL;DR

This study measures the underlying event activity in proton-proton collisions at 13 TeV using Z boson events, comparing data with Monte Carlo predictions and previous measurements at lower energies.

Contribution

It provides the first detailed measurement of underlying event activity in Z boson production at 13 TeV, enhancing understanding of QCD processes in high-energy collisions.

Findings

Underlying event activity increases with collision energy.

Distributions are well modeled by certain Monte Carlo generators.

Results are consistent with previous measurements at 1.96 and 7 TeV.

Abstract

This paper presents a measurement of the underlying event activity in proton-proton collisions at a center-of-mass energy of 13 TeV, performed using inclusive Z boson production events collected with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 2.1 fb$^{-1}$. The underlying event activity is quantified in terms of the charged particle multiplicity, as well as of the scalar sum of the charged particles' transverse momenta in different topological regions defined with respect to the Z boson direction. The distributions are unfolded to the stable particle level and compared with predictions from various Monte Carlo event generators, as well as with similar CDF and CMS measurements at center-of-mass energies of 1.96 and 7 TeV respectively.