A Constraint on the x Dependence of the Light Antiquarks Ratio
  We perform a careful study on the effect of the Pauli blocking to the light antiquark structure of the proton sea. We develop the formal expressions for the antiquark distributions, highlighting the role played by quark statistics and the vacuum structure. Ratios involving the antiquarks are calculated. In particular, it is found that $\Delta\bar{d}(x)/\Delta\bar{u}(x)$ should be negative and x independent. 
F. M. Steffens