"AQCD analysis is reported of ATLAS data on inclusive W-+\/- and Z boson production in pp collisions at the LHC, jointly with ep deep-inelastic scattering data from HERA. The ATLAS data exhibit sensitivity to the light quark sea composition and magnitude at Bjorken x similar to 0:01. Specifically, the data support the hypothesis of a symmetric composition of the light quark sea at low x. The ratio of the strange-to-down sea quark distributions is determined to be 1:00(-0:28)(+0.25) at absolute four-momentum transfer squared Q(2) = 1: 9 GeV2 and x = 0: 023."
Aad, G., Abbott, B., Abdallah, J., Abdelalim, A.a., Abdesselam, A., Abdinov, O., et al. (2012). Determination of the Strange-Quark Density of the Proton from ATLAS Measurements of the W -> lv and Z -> ll Cross Sections. PHYSICAL REVIEW LETTERS, 109(1), 1-17 [10.1103/PhysRevLett.109.012001].