In high-energy collisions, massive heavy quarks are produced back-to-back initially and they are sensitive to early dynamical conditions. The strong collective partonic wind from the fast expanding quark-gluon plasma created in high-energy nuclear collisions modifies the correlation pattern significantly. As a result, the angular correlation function for D$bar{rm D}$ pairs is suppressed at the angle $Deltaphi=pi$. While the hot and dense medium in collisions at RHIC ($sqrt{s_{NN}}=200$ GeV) can only smear the initial back-to-back D$bar {rm D}$ correlation, a clear and strong near side D$bar{rm D}$ correlation is expected at LHC ($sqrt{s_{NN}}=5500$ GeV).
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