Precision Measurement Of Forward Z Boson Production Cross-section At LHCb

In this article,a measurement of Z bosons production cross-section at(?)=13TeV is presented,using pp collision data collected by the LHCb detector in 2016,2017 and 2018.The integrated luminosity of data sets used in this analysis is 5.1±0.1 fb-1.The production cross-section is measured in the LHCb fiducial region,using Z? ?+?-events.The LHCb fiducail region is defined as that muons are required withinpseudorapidity range of 2.0<?<4.5,transverse momenta,PT>20GeV/c,anddimuon invariant mass is in range 60<M<120GeV/c2.Measurements aremade of the Z boson cross-section in the LHCb fiducial acceptance,and as a function of the Z boson rapidity,transverse momentum and ??*In order to get proper modelling of background,we used both real data and simulated samples to estimate background contributions from different physics processes.After background subtraction,the data distributions are corrected for efficiency.For the differential cross section measurement as a function of Z boson PT and yZ-PT,we use the RooUnfold method to suppress the effects from the detector.We alsoconsider a correction for the final state radiation effects.Finally,the systematic uncertainties are studied,and the final results are presented.The measured results are the most precise results in the forward region to date,which are consistent with different the Standard Model predictions.The measured results are compared to different theoretical predictions,including prediction at next-to-next-to-leading order in perturbative quantum chromodynamics,as well as other predictions using different generators.The results provide import experimental in-puts for the tests of the Standard Model and the constraint of parton distribution functions..