Open Charm Measurements in STAR

Haibin Zhang

Charm quarks can provide a unique tool to probe the partonic matter created in relativistic heavy-ion collisions at RHIC energies. First, charm quarks are produced via initial parton fusion due to its relatively large mass. Second, interactions of charm quarks with the surrounding partons in the medium can change their flow properties, which in turn allows us to study the possible thermalization processes of the hot and dense partonic medium. Third, studies of high $p_T$ charm energy loss in relativistic heavy-ion collisions can enable us to better understand the mechanisms of the jet quenching phenomenon.

In this talk we will present the measurements of the directly reconstructed $D0$ spectra, the charm decayed single electron spectra and nuclear modification factors. The charm production total cross-section per nucleon-nucluon collisions roughly follows the $N_{bin}$ scaling from d+Au to Au+Au collision, which indicates that charm quarks are mostly produced from initial parton fusion at early stages in relativisitic heavy-ion collisions. The single electron nuclear modification factor ($R_{AA}$) is found to be suppressed as strongly as that of light hadrons. The charm quarks produced in relativistic heavy-ion collisions must have been modified by the hot and dense medium.