Hallo Peter,

vielen Dank fuer die detaillierte Antwort!

In case of the total charm cross section, I had completely misunderstood what the paper was trying to say. I found this out when discussing the issue with Bernhard. I wonder if it wouldn't be even clearer of one would write (p 7 col 1):
"From the fractions ... is found to account for f_D = 89.1...%. Assuming the same fraction, the present study
derives the charm cross section per nucleon to
sigma(ccbar)=(sigma(D0)+sigma(D+)+sigma(Ds))/(2 f_D),
where the factor 2 accounts for the charge-conjugated states which are included in the D cross sections." or similar

On the pt distribution, I still have trouble figuring out what the description is tyring to say. The problem is the "The distribution of background events N(pt2)..." sentence. (Unfortunately, Bernhard is away otherwise I could ask him). I would think, that one can either measure the Xsect in some pt bins by sideband subtraction and then fit the pt-dependent Xsect with some shape. Then, one doesn't need a parametrization for the pt-dependence of the background. Or one does some kind of global fit, assuming a shape of the pt-dependence of the BG and of the signal. In the latter case, one doesn't get data points versus pt (as shown in the figure), but only some fit parameters. ... Did I make my problem clear - somehow I seem to misunderstand something??

Concerning Fig. 5: I suggest to mention explicitly that the normalization is fitted for each species independently. Also, it is not clear (to me) if the HERA-B point is included in the fit, or if the fit is seen as a summary of previous data. Maybe mention that.

Viele Gruesse,
Werner