Determination of proton parton distribution functions using ATLAS data

21 Nov 2019, 11:55
MPI & Small-x & diffraction MPI & Small-x & diffraction


Josef Pacalt for the ATLAS Collaboration (Palacky University (CZ))


We present fits to determine parton distribution functions (PDFs) using top-antitop,
inclusive W/Z-boson, as well as W+ and W− boson production measurements in
association with jets from ATLAS, in combination with deep-inelastic scattering data
from HERA. The ATLAS W and Z boson data exhibit sensitivity to the valence quark
distributions and the light quark sea composition, whereas the top-quark pair production
data have sensitivity to the gluon distribution. The impact of the top-antitop production
data is increased by fitting several distributions simultaneously, with the full information
on the systematic and statistical correlations between data points. The parton
distribution functions extracted using W+jets data show an improved determination of
the high-x sea-quark densities, while confirming the unsuppressed strange-quark
density at lower x<0.02 found by previous ATLAS analyses.

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