Non-photonic electron-hadron correlations and non-photonic electron $v_2$ at STAR/RHIC

Abstract

Non-photonic electrons (when $p_T >$ 3 GeV/$c$) represent the directions of the parent heavy quarks, and their angular correlations with charged hadrons provide a unique tool to study the relative contributions from $D$ and B meson decays in p+p collisions, as well as the flavor-dependence of the energy loss mechanism in A+A collisions. We review the disentanglement of charm and bottom contributions to non-photonic electrons in p+p collisions at $\sqrt{s} = 200$ GeV at RHIC. B decay contribution is approximately 50$ at the electron transverse momentum of $p_{T} > 5$ GeV/$c$ from STAR results. Incorporating the energy loss information of non-photonic electrons, the result indicates a B meson suppression at high $p_T$ in heavy ion collisions. We also present non-photonic electron-hadron correlations in d+Au collisions as a baseline reference for the investigation of the heavy quark energy loss in A+A collisions. Heavy quark energy loss and heavy quark evolution in the QCD medium can lead to a finite "elliptic flow" parameter ($v_2$) of $D$ and $B$ mesons which can be studied through $v_2$ of non-photonic electrons. Preliminary $v_2$ measurements for non-photonic electrons are shown to be lower than $v_2$ of charged hadrons (or $K_S^0$, $Λ$) for 200 GeV Au+Au collisions.