Heavy flavor production in nuclear collisions

Heavy flavor production off nuclei is studied in the small x(F) region of t he produced heavy system. Corrections to the usually employed perturbative QCD factorization formula are considered in the framework of the Glauber-Gr ibov model. Transition from low to high energies is taken into account by u sing finite energy cutting rules. The low energy limit of the obtained resu lts coincides with the probabilistic formula usually employed for quarkoniu m absorption. At finite energies both rescattering of the heavy flavor and corrections to nucleon parton densities inside nuclei appear, the latter al so affecting lepton pair production. It turns out that at asymptotic energi es both open heavy flavor and quarkonium are equally absorbed. The numerica l differences between the results obtained with the probabilistic formula a nd the exact one are < 20 % up to LHC energies, and <similar to> 1 divided by 2 % at SPS energies.