# Quark Matter 2012

12-18 August 2012
US/Eastern timezone

## STAR measurements of centrality dependence of elliptic flow for identified hadrons in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

16 Aug 2012, 16:00
2h

Poster Global and collective dynamics

### Speaker

Dr Hiroshi Masui (LBNL)

### Description

Elliptic flow $v_2$ is one of the key observables to study the bulk properties at freeze-out as well as hadron production mechanisms in the ultra relativistic heavy ion collisions. It has been observed that number of constituent quark (NCQ) scaling of $v_2$ holds among measured identified hadrons at $\sqrt{s_{NN}}$ = 62.4 and 200 GeV in Au + Au collisions at RHIC. The scaling of $v_2$ strongly indicates that the collectivity develops at the stage where the partonic degrees of freedom are relevant. Studying the NCQ scaling of $v_2$ as a function of transverse momentum $p_T$ and centrality will shed light on the production mechanisms for hadrons in heavy ion collisions. We present the results of $v_2$ as a function of $p_T$ for identified $\pi^{\pm}$, $K^{\pm}$, $K^0_S$, $p$, $\bar{p}$, $\Lambda$ and $\bar{\Lambda}$ in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The NCQ scaling of $v_2$ in several different centrality classes is discussed.

### Primary author

Dr Hiroshi Masui (LBNL)

 Poster