ResBos and ePump Analysis on ATLAS 8TeV Z Boson Transverse Momentum Distributions

Fixed-order predictions cannot describe the vector boson production process in low transverse momentum regions where resummation of soft gluon emission is essential. Using a ResBos Monte Carlo package, we perform the resummed theoretical predictions for the transverse momentum distributions of Z boson measured in proton-proton collision at $\sqrt{s}=8$TeV with ATLAS detector at LHC. We compare our results with data and fixed-order NNLO predictions. We find that the ResBos predictions significantly improve the agreement between the data and theory until the transverse momentum of the boson exceeds its invariant mass. However, in the high transverse momentum region, ResBos predictions approximate to fixed-order NNLO calculations and cannot describe well the data, the deviation between data and theory can be covered by the scale uncertainty. In addition, we study the impact of absolute and normalized ATLAS 8TeV Z boson transverse momentum distributions on CT18NNLO PDFs considering the low transverse momentum region where the ResBos predictions are reliable. We find that the traverse momentum distributions in the mass region 66 GeV $< M$_{ll}$ < 116$ GeV have a significant impact on CT18NNLO PDFs, benefiting from the high precision of the data. Furthermore, we demonstrate that absolute and normalized distributions have approximately the same impact on the PDFs.