Shengli Huang Vanderbilt University for the PHENIX Collaboration

1. Measurements of high pT identified hadron v2 in 200GeV Au+Au collisions by the PHENIX experiment Shengli Huang Vanderbilt University for the PHENIX Collaboration

2. Outline: • Observables andMotivation • Analysis methods • Results and Discussion • Conclusions S.L. Huang DNP08

3. reaction plane beam x y Anisotropic flow v2 and v4 Peter Kolb, PRC 68, 031902 momentum space asymmetry Spatial space asymmetry • Azimuthal correlation with the reaction plane • Built up in the early stage and self-quenched, therefore supply the early information of matter generated in the collision S.L. Huang DNP08

4. NCQ Scaling PHENIX,PRL. 99, 052301 (2007) • Baryon and meson elliptic flow follow the number of constituent quark(NCQ) scaling as a function of KET at low KET. • NCQ scaling will break at intermediate pT if we assume that  is mainly from the recombination of TS partons but proton is mainly from TTS and TSS . • NCQ scaling indicates the coalescence of the thermal partons • Can we test this scaling break at high pT? Hwa &&Yang arXiv:0801.2183[nucl-th] SL Huang DNP08

5. 2 D E <q> ^ L  a C s Color Charge dependence 1.Gluon will lose more energy by gluon radiation in medium 2.The contribution from gluon jet fragmentation is different for pion, kaon(KS) and proton. The measurements of pion, kaon and proton and their anti-particles’ v2 will help us to study the color charge effect on energy loss S. Wicks et al,Nucl.Phys.A784:426-442,2007 S. Albino, B.A. Kniehl, G. Kramer, NPB 725 (2005) 181 SL Huang SQM08

6. TOFw and Aerogel Detectors • TOFw intrinsic timing resolution is ~ 75ps • /K can be separated to 2.8 GeV/c and K/p can be separated • to 4.5 GeV/c • 3. Together with Aerogel detector(ACC), we can identify the K to • pT~4 GeV/c and , p to 7 GeV/c SL Huang DNP08

7. Reaction plane Measurements • RxNP: • Two sets of plastic • scintillators positioned • on either side of the • collision vertex • 12 segments in  • 2 segments in  • 1.0 < || < 1.5 • 1.5 < || < 2.8 • BBC: • 3.1<||<3.9 • Both detectors are away from mid-rapidity. Smaller non-flow effect • on the reaction plane measurements • New RxNP detector resolution is around 74% at mid-centrality Sqrt(2*cos(2*(N-S))) SL Huang DNP08

8. Identified particles elliptic flow • The proton’s v2 approaches to pion’s v2 as pT increases. It indicates the baryron production smoothly transits from TTT->TTS->TSS->SSS • The kaon’s v2 is similar to the pion’s v2 as a function of KET. • If particles production is dominated by jet fragmentation as pT~6GeV/c, the data indicates that the gluon will lose similar energy as light quark SL Huang DNP08

9. NCQ Scaling The NCQ scaling is broken as KET/nq>1GeV. It is consistent with theory calculation by assuming that the pion is from TS recombination but the proton is from TTS or TSS recombination at intermediate pT SL Huang DNP08

10. Charge Dependence K+, k- and proton, anti-proton have similar v2 as a function of pT SL Huang DNP08

11. Conclusions 1. The proton’s v2 approaches to the pion’s v2 at pT~6GeV/c. And the kaon’s v2 is similar with pion’s v2 as a function of KET. 2. The NCQ scaling is broken at KET/nq~1GeV/c. It supports a two components (thermal and shower) partons recombination model at intermediate pT. 3. The proton and kaon have similar v2 to their anti-particles v2. SL Huang DNP08