The elliptic azimuthal anisotropy coefficient (v2) is measured for charm (D0) and strange (K0
S, Λ, Ξ−,
and Ω−) hadrons, using a data sample of p þ Pb collisions collected by the CMS experiment, at a nucleonnucleon center-of-mass energy of ffiffiffiffiffiffiffi
sNN p ¼ 8.16 TeV. A significant positive v2 signal from long-range
azimuthal correlations is observed for all particle species in high-multiplicity p þ Pb collisions. The
measurement represents the first observation of possible long-range collectivity for open heavy flavor
hadrons in small systems. The results suggest that charm quarks have a smaller v2 than the lighter quarks,
probably reflecting a weaker collective behavior. This effect is not seen in the larger PbPb collision system
at ffiffiffiffiffiffiffi
sNN p ¼ 5.02 TeV, also presented