Directed flow of identified particles from Au+Au collisions at RHIC

We present the measurement of directed flow (v1) for the identified particles, namely, Λ, Λ-bar and Ks0, as a function of rapidity and centrality in Au+Au collisions at √SNN = 200 GeV and 62.4 GeV. The measurement is based on the run IV data obtained by the STAR experiment at RHIC. In order to enhance event plane resolution, we use tracks reconstructed from the Forward Time Projection Chambers (FTPCs), together with the sideward deflection of spectator neutrons measured by the STAR's Shower Maximum Detector at Zero Degree Calorimeters (ZDC-SMDs). We find that for 200 GeV, proton and antiproton v1 is less than 1%, the Ks0, Λ, Λ-bar, v1 is less than 2% for 62 GeV, proton v1 is less than 1% and antiproton is less than 2%, v1 for Ks0, Λ, Λ-bar is less than 2% in Au+Au collisions at 200 GeV. (author)