Hadronic fluctuations and quark-antiquark asymmetry in the nucleon
  We derive the nucleon non-perturbative sea-quark distributions coming from a composite model involving quarks and hadronic degrees of freedom. The model predicts a definite structured quark-antiquark asymmetry in the nucleon sea. 
H.R. Christiansen, J. Magnin (C.B.P.F - Rio de Janeiro)