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Shengli Huang Vanderbilt University for the PHENIX Collaboration

Measurements of  , K and proton v 2 and v 4 in 200GeV Au+Au collisions by the PHENIX experiment. Shengli Huang Vanderbilt University for the PHENIX Collaboration. Outline:. Observables and Motivation Analysis methods Results and Discussion Conclusions. reaction plane. beam. x. y.

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Shengli Huang Vanderbilt University for the PHENIX Collaboration

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  1. Measurements of , K and proton v2 and v4 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 SQM08

  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 SQM08

  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 parton • How about the higher order anisotropic flow such as v4? • Can we test this scaling break at high pT? Hwa &&Yang arXiv:0801.2183[nucl-th] SL Huang SQM08

  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. Star Preliminary V4/(v2)2 ratio • v4 /v22 is a probe of ideal • hydro behavior and related to • the degree of thermalization! • Peter Kolb, PRC 68, 031902(2003); • R.S.Bhalerao et.al PLB 627,49(2005); • Borghini and Ollitrault,PLB642,227 • (2006) • The identified particles • v4/v22 ratio should provide more • detailed information than • that of charged hadron Y.T. Bai QM06 S.L. Huang SQM08

  7. 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 SQM08

  8. 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 SQM08

  9. 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 QM08

  10. 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 QM08

  11. KET Scaling of v4 A.Taranenko • The v4 follows the KET scaling well for KET < 1 GeV • The number of constituent quark scaling holds for v4 when • KET/nq < 1GeV. This confirms that matter with partonic degrees • of freedom has been generated at RHIC S.L. Huang SQM08

  12. V4/(v2)2 ratio • The ratio of v4/(v2)2 is close to • 0.9 for the , K and p • Mesons and baryons have similar v4/(v2)2 ratio S.L. Huang SQM08

  13. Recombination at Intermediate pT How to Coalesce? Simple co-mover model at low pT Meson Meson thermal Baryon Baryon L.W. Chen, C.M. Ko nucl-th 0602025 shower baryon(TTS) Not only at intermediate pT region, even at low pT region, the particle is coalesced by the partons with different momentum SL Huang QM08

  14. Conclusions 1. The number of constituent quark scaling has been observed for v4 for KET/nq < 1 GeV. Mesons and baryons have similar v4/(v2)2 ratio which is close to 0.9 2. 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. 3. The NCQ scaling is broken at KET/nq~1GeV SL Huang SQM08

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