  We report on broadly based systematic investigations of the modeling
components for open heavy-flavor diffusion and energy loss in strongly
interacting matter in their application to heavy-flavor observables in
high-energy heavy-ion collisions, conducted within an EMMI Rapid Reaction Task
Force framework. Initial spectra including cold-nuclear-matter effects, a wide
variety of space-time evolution models, heavy-flavor transport coefficients,
and hadronization mechanisms are scrutinized in an effort to quantify pertinent
uncertainties in the calculations of nuclear modification factors and elliptic
flow of open heavy-flavor particles in nuclear collisions. We develop
procedures for error assessments and criteria for common model components to
improve quantitative estimates for the (low-momentum) heavy-flavor diffusion
coefficient as a long-wavelength characteristic of QCD matter as a function of
temperature, and for energy loss coefficients of high-momentum heavy-flavor
particles.

Nuclear Theory;High Energy Physics - Phenomenology;Nuclear Experiment