  Charm elliptic flow in heavy ion collisions at the Relativistic Heavy Ion
Collider (RHIC) is studied in a multiphase transport model. Assuming that the
cross section for charm quark scattering with other light quarks is the same as
that between light quarks, we find that both charm and light quark elliptic
flows are sensitive to the value of the cross section. Compared to that of
light quarks, the elliptic flow of charm quarks is smaller at low transverse
momentum but approaches comparable values at high transverse momentum. Similar
features are seen in the elliptic flow of charmed mesons as well as that of the
electrons from their semileptonic decays when the charmed mesons are produced
from quark coalescence during hadronization of the partonic matter. To describe
the large electron elliptic flow observed in available experimental data
requires a charm quark scattering cross section that is much larger than that
given by the perturbative QCD.
