I looked at events where c,cbar -> any D or D* -> single muon, requiring a hit in the first and the last Si plane of the North Silicon endcap. and plotted DCA for various ptot intervals:

Ptot range (GeV) DCA (um)
1-2 133
2-3 103
3-4 74
4-5 72

DCA goes down with Ptot. Although boost increases z of the secondary mu vertex, the d->mu decay angle decreases with boost. In addition, higher momenta tracks tend to be at shallower angles. The net effect is a decrease of DCA with Ptot



Last update 9 dec 05 HvH