Determination of the parton distribution functions of the proton from ATLAS measurements of differential $W^\pm$ and $Z$ boson production in association with jets

This article presents a new set of proton parton distribution functions, ATLASepWZVjet20, produced in an analysis at next-to-next-to-leading-order in QCD. The new datasets considered are the ATLAS measurements of $W^+$ , $W^-$ and $Z$ boson production in association with jets in $pp$ collisions at $\sqrt{s} = 8~\mathrm{TeV}$ at the LHC with integrated luminosities of $20.2~\mathrm{fb}^{-1}$ and $19.9~\mathrm{fb}^{-1}$, respectively. The analysis also considers the ATLAS measurements of differential $W^{\pm}$ and $Z$ boson production at $\sqrt{s} = 7~\mathrm{TeV}$ with an integrated luminosity of $4.6~\mathrm{fb}^{-1}$ and deep-inelastic scattering data from $e^{\pm}p$ collisions at the HERA accelerator. An improved determination of the sea-quark densities at high Bjorken $x$ is shown, while confirming a strange-quark density of similar size as the up-and down-sea quark densities in the range $x \lesssim 0.02$ found by previous ATLAS analyses.