Heavy flavor as a probe of hot QCD matter produced in proton-proton collisions

The creation of a quark-gluon plasma (QGP) is expected in heavy-ion collisions. It came as a surprise that proton-proton collisions at ultrarelativistic energies show as well a "QGP-like" behavior and signs of the creation of a fluid, although the corresponding system size is not more than a few cubic femtometers. Even more surprisingly, also heavy-flavor particles seem to be part of the fluid or at least interact with it. In this paper, we will investigate in a quantitative way this "collective behavior" of heavy flavor, by employing the newly developed EPOS4HQ approach, which has proven to be compatible with basic experimental data of light-flavor hadrons. We will investigate all observables, which may manifest collectivity, as particle spectra, elliptic flow, baryon-to-meson ratios, and two-particle correlations, and compare the results with experimental data. We will try to disentangle initial-state effects, those being due to interactions between charm quarks and plasma partons, and final-state effects (hadronization).