Elliptic Flow of Electrons from Heavy-Flavor Hadron Decays in Au + Au Collisions at √\u3cem\u3e\u3csup\u3es\u3c/sup\u3e\u3csub\u3eNN\u3c/sub\u3e\u3c/em\u3e = 200, 62.4, and 39 GeV
We present measurements of elliptic flow (ν2) of electrons from the decays of heavy-flavor hadrons (eHF) by the STAR experiment. For Au+Au collisions at √sNN = 200 GeV we report v2, for transverse momentum (pT) between 0.2 and 7 GeV/c, using three methods: the event plane method (v2{EP}), two-particle correlations (v2{2}), and four-particle correlations (v2{4}). For Au+Au collisions at √sNN = 62.4 and 39 GeV we report v2{2} for pT \u3c 2 GeV/c. v2{2} and v2{4} are nonzero at low and intermediate pT at 200 GeV, and v2{2} is consistent with zero at low pT at other energies. The v2{2} at the two lower beam energies is systematically lower than at √sNN = 200 GeV for pT \u3c 1GeV/c. This difference may suggest that charm quarks interact less strongly with the surrounding nuclear matter at those two lower energies compared to √sNN = 200 GeV
