Asymmetries in Heavy Meson Production from Light Quark Fragmentation
  We discuss the possibility of the asymmetry in $D^-/D^+$ production, from $\pi^-$ beams, being a direct consequence of the properties of the light quark fragmentation function into heavy mesons. The main features of the asymmetry, as a function of $x_F$, are easily described. An integrated sum-rule for the $D^-, D^+$ difference, is presented. Predictions for the asymmetry, in $B$ meson production, are given. 
J. Dias de Deus and F. O. Duraes