Parton distributions from high-precision collider data

by Juan Rojo (Nikhef/Amsterdam)

Thursday, 13 July 2017 from to (Europe/Berlin)
at Physikdepartment ( HS3 )
I present a new set of parton distributions, NNPDF3.1, which updates the first global set of PDFs determined using a methodology validated by a closure test, NNPDF3.0. On the methodological side, we now fit the charm PDF alongside the light quarks and gluons, thereby increasing from seven to eight the number of independent PDFs. On the data side, we now include the D0 electron and muon W asymmetries  from the final Tevatron dataset, the complete LHCb measurements of W and Z production in the forward region at 7 and 8 TeV, and new ATLAS and CMS measurements of inclusive jet and electroweak boson production. We now also for the first time include top-quark pair differential distributions and the transverse momentum  of the Z bosons from ATLAS and CMS. We study the impact of the new data included in the fit by producing a variety of determinations based on reduced datasets. We find that both improvements in methodology and dataset have a significant impact on the PDFs, with a significant reduction in uncertainty of up to about a factor two, but with the new PDFs generally in agreement with the previous set at the one sigma level. The most significant changes are seen in the light-quark flavor separation. We explore the implications of NNPDF3.1 for LHC phenomenology at Run II, compare with recent LHC measurements at 13 TeV, provide updated predictions for Higgs production cross-sections and discuss the strangeness and charm content of the proton in light of our improved dataset and methodology.