Dynamical Symmetry Breaking in the Sea of the Nucleon
  We derive the non-analytic chiral behavior of the flavor asymmetry dbar - ubar. Such behavior is a unique characteristic of Goldstone boson loops in chiral theories, including QCD, and establishes the unambiguous role played by the Goldstone boson cloud in the sea of the proton. Generalizing the results to the SU(3) sector, we show that strange chiral loops require that the s - sbar distribution be non-zero. 
A.W. Thomas, W. Melnitchouk and F.M. Steffens