QM 2011 - XXII International Conference on Ultrarelativistic Nucleus-Nucleus Collisions

May 22 – 28, 2011
Centre Bonlieu
Europe/Zurich timezone

Directed flow of Identified Particles in Au+Au Collisions at $\sqrt{s_{NN}}$= 39, 11.5 and 7.7 GeV from the STAR Experiment

Not scheduled
Théâtre National (Centre Bonlieu)

Théâtre National

Centre Bonlieu

France
Board: 17
Poster Global and collective dynamics

Speaker

Yadav Pandit (For the STAR Collaboration)

Description

Measurements of anisotropic flow in heavy-ion collisions provide insight into the early stage of the system's evolution. Directed flow, $v_1$, is imparted especially early. A change of sign in the slope of $dv_1/dy$ for identified particles, particularly for protons, has been suggested as a possible signal of a first-order phase transition. In this talk, we present the STAR measurements of $v_1$ for $\pi^\pm$, $K^\pm$, protons and antiprotons, as well as for all detected charged particles in Au + Au collisions at $\sqrt{s_{NN}}$ = 39, 11.5 and 7.7 GeV as a function of transverse momentum, rapidity and centrality. At $\sqrt{s_{NN}}$ = 39 GeV, all measured $v_1$ values follow the trend observed at higher RHIC energies. At $\sqrt{s_{NN}}$ = 11.5 and 7.7 GeV, the proton $dv_1/dy$ near midrapidity changes sign between peripheral and central collisions. This behavior is not observed for antiprotons, $\pi^\pm$ and $K^\pm$. Results are compared to available model predictions.

Primary author

Yadav Pandit (For the STAR Collaboration)

 Poster