Left: prompt fraction $f_{\rm prompt}$ of the $\Dzero$ raw yield as a function of $\pt$, for the two FONLL-based methods (solid: central value, from Eq.2; dashed: alternative method, from Eq.4) and for the impact parameter fit method (circles); the boxes show the envelope of the uncertainty bands of the two FONLL-based methods; the error bars show the total uncertainty from the impact parameter fit, including the statistical and systematic contributions Right: an example of $\Dzero$ meson impact parameter distribution in the transverse plane, for $2< \pt< 3 \gev/c$; the distribution is background-subtracted and fitted with the two-component function for prompt and feed-down contributions, as described in the text; the resulting prompt fraction, impact parameter resolution for prompt mesons, and $\chi^2$/(number of degrees of freedom) of the fit are given; the inset, with linear scale, shows also the negative entries, resulting from the background subtraction.
$$\begin{align*} (2)   f_{\rm prompt}=1-(N^{\rm D^\pm from B raw}/N^{\rm D^\pm raw}) \end{align*}$$ $$\begin{align*} (4)   f_{\rm prompt}= \left( 1+ \frac{({\rm Acc}\times\epsilon)_\text{feed-down} }{({\rm Acc}\times\epsilon)_{\rm prompt} } \frac{\left.\frac{{\rm d}\sigma_{\rm FONLL}^{\rm D^+ from B}}{{\rm d}\pt}\right|_{|y|< 0.5}}{\left.\frac{{\rm d}\sigma_{\rm FONLL}^{\rm D^+}}{{\rm d}\pt}\right|_{|y|< 0.5}}\right)^{-1}\, \end{align*}$$