  The ratio of nuclear modification factors of high-pT heavy-flavored mesons to
light-flavored hadrons (``heavy-to-light ratio'') in nucleus-nucleus collisions
tests the partonic mechanism expected to underlie jet quenching. Heavy-to-light
ratios are mainly sensitive to the mass and color-charge dependences of
medium-induced parton energy loss. Here, we assess the potential for
identifying these two effects in D and B meson production at RHIC and at the
LHC. To this end, we supplement the perturbative QCD factorized formalism for
leading hadron production with radiative parton energy loss. For D meson
spectra at high but experimentally accessible transverse momentum (10 < pT < 20
GeV) in Pb-Pb collisions at the LHC, we find that charm quarks behave
essentially like light quarks. However, since light-flavored hadron yields are
dominated by gluon parents, the heavy-to-light ratio of D mesons is a sensitive
probe of the color charge dependence of parton energy loss. In contrast, due to
the larger b quark mass, the medium modification of B mesons in the same
kinematical regime provides a sensitive test of the mass dependence of parton
energy loss. At RHIC energies, the strategies for identifying and disentangling
the color charge and mass dependence of parton energy loss are more involved
because of the smaller kinematical range accessible. We argue that at RHIC, the
kinematical regime best suited for such an analysis of D mesons is 7 < pT < 12
GeV, whereas the study of lower transverse momenta is further complicated due
to the known dominant contribution of additional, particle species dependent,
non-perturbative effects.
