4 research outputs found

    Epps16 ⇓ first nuclear pdfs to include lhc data

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    We present results of our recent EPPS16 global analysis of NLO nuclear parton distribution functions (nPDFs). For the first time, dijet and heavy gauge boson production data from LHC proton–lead collisions have been included in a global fit. Especially, the CMS dijets play an important role in constraining the nuclear effects in gluon distributions. With the inclusion of also neutrino–nucleus deeply-inelastic scattering and pion–nucleus Drell–Yan data and a proper treatment of isospin-corrected data, we were able to free the flavor dependence of the valence and sea quark nuclear modifications for the first time. This gives us less biased, yet larger, flavor by flavor uncertainty estimates. The EPPS16 analysis indicates no tension between the data sets used, which supports the validity of collinear factorization and universal nPDFs for nuclear hard-collision processes in the kinematical range studied. © Copyright owned by the author(s).Peer reviewe

    Signatures of gluon saturation from structure-function measurements

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    We study experimentally observable signals for nonlinear QCD dynamics in deep inelastic scattering (DIS) at small Bjorken variable x and moderate virtuality Q(2), by quantifying differences between the linear Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution and nonlinear evolution with the Balitsky-Kovchegov equation. To remove the effect of the parametrization freedom in the initial conditions of both equations, we first match the predictions for the DIS structure functions F-2 and F-L from both frameworks in a region in x, Q(2) where both frameworks should provide an accurate description of the relevant physics. The differences in the dynamics are then quantified by the deviations when one moves away from this matching region. For free protons we fmd that the differences in F-2 remain at a few-percent level, while in F-L the deviations are larger, up to 10% at the Electron Ion Collider (EIC) and 40% at the Large Hadron-electron Collider (LHeC) kinematics. With a heavy nucleus the differences are up to 10% in F-2, and can reach 20% and 60% in F-L for the EIC and the LHeC, respectively.Peer reviewe

    Predictions for cold nuclear matter effects in p plus Pb collisions at root SNN =8.16 TeV

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    Predictions for cold nuclear matter effects on charged hadrons, identified light hadrons, quarkonium and heavy flavor hadrons, Drell-Yan dileptons, jets, photons, gauge bosons and top quark pairs produced in p+Pb collisions at, root S-NN = 8.16 TeV are compiled and, where possible, compared to each other. Predictions of the normalized ratios of p+Pb to p+ p cross sections are also presented for most of the observables, providing new insights into the expected role of cold nuclear matter effects. In particular, the role of nuclear parson distribution functions on particle production can now be probed over a wider range of phase space than ever before. (C) 2018 Elsevier B.V. All rights reserved.Peer reviewe
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