  Angular correlations between heavy-quarks provide a unique probe of the
quark-gluon plasma created in ultra-relativistic heavy-ion collisions. Results
are presented of a measurement of the azimuthal angle correlations between
muons originating from semileptonic decays of heavy-quarks produced in 5.02 TeV
Pb+Pb and $pp$ collisions at the LHC. The muons are measured with transverse
momenta and pseudorapidities satisfying $p_{\mathrm{T}}^\mu > 4$ GeV and
$|\eta^\mu|<2.4$, respectively. The distributions of azimuthal angle
separation, $\Delta\phi$, for muon pairs having pseudorapidity separation
$|\Delta\eta|>0.8$, are measured in different Pb+Pb centrality intervals and
compared to the same distribution measured in $pp$ collisions at the same
center-of-mass energy. Results are presented separately for muon pairs with
opposite-sign charges, same-sign charges, and all pairs. A clear peak is
observed in all $\Delta\phi$ distributions at $\Delta\phi\sim\pi$, consistent
with the parent heavy-quark pairs being produced via hard-scattering processes.
The widths of that peak, characterized using Cauchy-Lorentz fits to the
$\Delta\phi$ distributions, are found to not vary significantly as a function
of Pb+Pb collision centrality and are similar for $pp$ and Pb+Pb collisions.
This observation will provide important constraints on theoretical descriptions
of heavy-quark interactions with the quark-gluon plasma.
