  In high-energy nuclear collisions at LHC, where a QGP might be created, the
degree of thermalization at the partonic level is a key issue. Due to their
large mass, heavy quarks are a powerful tool to probe thermalization. We
propose to measure azimuthal correlations of heavy-quark hadrons and their
decay products. Changes or even the complete absence of these initially
existing azimuthal correlations in $Pb-Pb$ collisions might indicate
thermalization at the partonic level. We present studies with PYTHIA for $p-p$
collisions at 14 TeV using the two-particle transverse momentum correlator
${<\overline{\Delta}p_{t,1}\overline{\Delta}p_{t,2}>}$ as a sensitive measure
of potential changes in these azimuthal correlations. Contributions from
transverse radial flow are estimated.
