The prompt contribution to the atmospheric neutrino flux is analyzed. It is
demonstrated that the corresponding theoretical uncertainties related to
perturbative treatment of charm production, notably, the ones stemming from the
low and high x behavior of parton distribution functions, can be conveniently
studied at the level of charm quark production. Additionally, we discuss the
non-perturbative contribution to the prompt neutrino flux, related to the
intrinsic charm content of the proton, and analyze its main features.Comment: v2: accepted versio