title: New limits on intrinsic charm in the nucleon from global analysis of parton distributions.
abstract: We present a new global QCD analysis of parton distribution functions, allowing for possible intrinsic charm (IC) contributions in the nucleon inspired by light-front models. The analysis makes use of the full range of available high-energy scattering data for Q^{2}≳1  GeV^{2} and W^{2}≳3.5  GeV^{2}, including fixed-target proton and deuteron cross sections at lower energies that were excluded in previous global analyses. The expanded data set places more stringent constraints on the momentum carried by IC, with ⟨x⟩_{IC} at most 0.5% (corresponding to an IC normalization of ∼1%) at the 4σ level for Δχ^{2}=1. We also critically assess the impact of older EMC measurements of F_{2}^{c} at large x, which favor a nonzero IC, but with very large χ^{2} values.
authors.affiliation: Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606, USA.
authors.forename: P
authors.initials: P
authors.lastname: Jimenez-Delgado
authors.affiliation: Department of Physics and Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47405, USA.|Department of Physics, University of Washington, Seattle, Washington 98195, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Hobbs
authors.affiliation: Department of Physics and Center for Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47405, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Londergan
authors.affiliation: Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606, USA.
authors.forename: W
authors.initials: W
authors.lastname: Melnitchouk