Luminosity determination using Z boson production at the CMS experiment

TL;DR

This paper presents a novel method for determining the integrated luminosity of CMS data sets using Z boson production, achieving high precision and a comprehensive uncertainty analysis, thus enhancing luminosity measurement accuracy.

Contribution

The study introduces a new Z boson-based approach for luminosity determination with a full uncertainty analysis, improving precision over traditional methods.

Findings

Uncertainty in extrapolation between data sets is less than 0.5%.

Z boson rate measurement provides a precise, complementary luminosity measurement method.

Method demonstrates potential to improve overall luminosity accuracy.

Abstract

The measurement of Z boson production is presented as a method to determine the integrated luminosity of CMS data sets. The analysis uses proton-proton collision data, recorded by the CMS experiment at the CERN LHC in 2017 at a center-of-mass energy of 13 TeV. Events with Z bosons decaying into a pair of muons are selected. The total number of Z bosons produced in a fiducial volume is determined, together with the identification efficiencies and correlations from the same data set, in small intervals of 2 pb$^{-1}$ of integrated luminosity, thus facilitating the efficiency and rate measurement as a function of time and instantaneous luminosity. Using the ratio of the efficiency-corrected numbers of Z bosons, the precisely measured integrated luminosity of one data set is used to determine the luminosity of another. For the first time, a full quantitative uncertainty analysis of the use of Z bosons for the integrated luminosity measurement is performed. The uncertainty in the extrapolation between two data sets, recorded in 2017 at low and high instantaneous luminosity, is less than 0.5%. We show that the Z boson rate measurement constitutes a precise method, complementary to traditional methods, with the potential to improve the measurement of the integrated luminosity.