  In this paper we study the azimuthal correlations of heavy quarks in Pb+Pb
collisions with $\sqrt{s}=2.76$ TeV at LHC. Due to the interaction with the
medium heavy quarks and antiquarks are deflected from their original direction
and the initial correlation of the pair is broadened. We investigate this
effect for different transverse momentum classes. Low-momentum heavy-quark
pairs lose their leading order back-to-back initial correlation, while a
significant residual correlation survives at large momenta. Due to the larger
acquired average deflection from their original directions the azimuthal
correlations of heavy-quark pairs are broadened more efficiently in a purely
collisional energy loss mechanism compared to including radiative corrections.
This discriminatory feature survives when next-to-leading order production
processes are included.
