Intrinsic charm and the $D^+-D^-$ asymmetry produced in proton-proton collisions

We investigate the contribution of the charm-anticharm ($c{\bar c}$) asymmetry of the proton eigenstate obtained from QCD lattice gauge to the asymmetry of $D^+,D ^-$ and $D^0,{\bar D}^0$ mesons produced in $pp$ collisions at large Feynman variables $x$. Predictions for the asymmetry as function of $x$ for different probabilities of intrinsic charm ({\it IC}) in proton are presented.