Impacts From The LHCb Single W,Z Boson Data On Parton Distribution Functions Fitting

With better understanding on the material,the theories could describe most of fundamental interatcions precisely.But for Parton distribution functions(PDFs),since it cannot be theoretical calculated,it can only be obtained by a global fitting using the experimental results as inputs.The LHCb experiment of the Large Hadron Collider has a unique geometry acceptance,which can cover unique areas compare to other experiments,especially in the forward region.The pp collision data collected by the LHCb detector provides essential and complementary information for a PDFs fitting,compared to the data collected by the ATLAS and CMS detectors.This article is divided into two parts.The first part starts with an introduction of the Standard Model Electroweak theory,describes motivation of this analysis,and explains physics observable and methods used in the tests.In the second part,we studied impacts from the LHCb single W/Z boson production measurements and the lepton charge asymmetry measurements on the PDFs,using the Error PDF Updating method.To estimate potential of the LHCb data,two pseudo-data samples are used,corresponding to 5 fb-1 and 300 fb-1 of pp collision data at a center-of-mass energy of 13 TeV.With these pseudo-data samples as inputs,we found the d and d quark PDFs uncertainty are reduced dramatically,?30%improvement at momentum fraction(x)around 10-3.Furthermore,the LHCb data has large and unique impacts on the d quark over u quark PDFs ratio(d/u ratio)in the very large x region.While,the impacts on other flavour PDFs are negligible.Specially the measurement of Z Boson pr could improves the PDFs fitting more than other Z boson observable.Furthermore,for global analysis of PDFs in the future,we would like to emphasize that use dynamic tolerances rather than fixed tolerances,otherwise,the impacts on the PDFs fitting from the new input data will be significantly overestimated.