Abstract: | We present the measurement of directed flow (v
1) for the identified particles, namely, Λ, $
\bar \Lambda
$
\bar \Lambda
and K
s
0, as a function of rapidity and centrality in Au+Au collisions at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 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 v
1 is less than 1%, the K
s
0
Λ, $
\bar \Lambda
$
\bar \Lambda
v
1 is less than 2%; for 62 GeV, proton v
1 is less than 1% and antiproton is less than 2%, v
1 for K
s
0, Λ, $
\bar \Lambda
$
\bar \Lambda
is less than 2% in Au+Au collisions at 200 GeV. |