  Heavy quark parton distribution functions (PDFs) play an important role in
several Standard Model and New Physics processes. Most analyses rely on the
assumption that the charm and bottom PDFs are generated perturbatively by gluon
splitting and do not involve any non-perturbative degrees of freedom. It is
clearly necessary to test this hypothesis with suitable QCD processes.
Conversely, a non-perturbative, intrinsic heavy quark parton distribution has
been predicted in the literature. We demonstrate that to a very good
approximation the scale-evolution of the intrinsic heavy quark content of the
nucleon is governed by non-singlet evolution equations. This allows us to
analyze the intrinsic heavy quark distributions without having to resort to a
full-fledged global analysis of parton distribution functions. We exploit this
freedom to model intrinsic bottom distributions which are so far missing in the
literature in order to estimate the impact of this non-perturbative
contribution to the bottom-quark PDF, and on parton--parton luminosities at the
LHC. This technique can be applied to the case of intrinsic charm, albeit
within the limitations outlined in the following.
