  Soft-hadron measurements in high-energy collisions of small systems like p-Pb
and d-Au show peculiar qualitative features (long-range rapidity correlations,
flattening of the $p_T$-spectra with increasing hadron mass and centrality,
non-vanishing Fourier harmonics in the azimuthal particle distributions)
suggestive of the formation of a strongly-interacting medium displaying a
collective behaviour, with a hydrodynamic flow as a response to the pressure
gradients in the initial conditions. Hard observables (high-$p_T$ jet and
hadron spectra) on the other hand, within the current large systematic
uncertainties, appear only midly modified with the respect to the benchmark
case of minimum-bias p-p collisions. What should one expect for heavy-flavour
particles, initially produced in hard processes but tending, in the
nucleus-nucleus case, to approach kinetic equilibrium with the rest of the
medium? This is the issue we address in the present study, showing how the
current experimental findings are compatible with a picture in which the
formation of a hot medium even in proton-nucleus collisions modifies the
propagation and hadronization of heavy-flavour particles.
