Studying charm quark elliptic flow via single electron measurements

Abstract

The observed scaling of elliptic flow (v2) with the number of constituent quarks for mesons and baryons in Au+Au collisions at RHIC energies has theoretically been described through hadron production via quark coalescence from a thermalized parton system. Within the framework of quark coalescence, the elliptic flow of individual quark flavours can be deduced from v2 measurements of identified hadrons. While the light quarks are predominantly created in soft collisions, heavy quarks are believed to be created in hard collisions and are not expected to carry flow at the time of their production. An analysis of the elliptic flow of charmed hadrons, e.g. D-mesons, might therefore not only reveal information about charm quark flow, but also about hadronization and thermalization processes in heavy ion collisions. As direct v2 measurements of charmed hadrons are not available yet, single electron v2 at sufficiently high transverse momenta can serve as a substitute. The production of single electrons from non-photonic sources is expected to be dominated by the decay of D-mesons at transverse momenta between 2 GeV/c and 5 GeV/c. Simulations show a strong correlation between the flow of the D-meson and its decay electron in this momentum range. We will present preliminary STAR results from our single electron v2 measurements from Au+Au collisions at RHIC energies and compare with predictions from quark coalescence models.