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Measurement of the higher order azimuthal anisotropy (v n ) for charged hadrons at RHIC-PHENIX

Measurement of the higher order azimuthal anisotropy (v n ) for charged hadrons at RHIC-PHENIX. John Chin-Hao Chen for PHENIX collaboration RIKEN Brookhaven Research Center NN2012 2012/05/31. v n : particle anisotropy.

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Measurement of the higher order azimuthal anisotropy (v n ) for charged hadrons at RHIC-PHENIX

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  1. Measurement of the higher order azimuthal anisotropy (vn) for charged hadrons at RHIC-PHENIX John Chin-Hao Chen for PHENIX collaborationRIKEN Brookhaven Research Center NN2012 2012/05/31 John C.-H. Chen

  2. vn: particle anisotropy • The colliding area is “almond” like shape due to overlap of two colliding nuclei. • The particle angular distribution: dN/d(f-y) =N0(S(1+2vncosn(f-yn))) • Nucleon distribution is not smooth, or initial state fluctuation -> finite vodd • We can “measure” the fluctuations directly John C.-H. Chen

  3. Many information coming from flow • Equation of State (EOS) • shear viscosity (η), • specific viscosity (η/s) of sQGP • and their temperature dependence • Key to understand the QGP! John C.-H. Chen

  4. v3, reason for ridge and shoulder? • Ridge sits at Df ~ 0, shoulder sits at Df~2p/3, 4p/3 • A 3-peak structure! • v3 (Fourier Coefficient of thecos3Df term) gives a natural 3-peak structure • Is v3 the explanation? John C.-H. Chen

  5. How do we measure vn? • Reaction plane method • Use forward detector to determine the n-th reaction plane, Yn • dN/df 1+S2vncos n(f-Yn) • vn = <cos n(f-Yn)> • Two particle correlation method • central-central or central-forward correlation • dNpair/dDf 1+S(2vnAvnBcosnDf) John C.-H. Chen

  6. John C.-H. Chen

  7. vn(Yn) vs pT PRL 107 252301 (2011) • All vn increases with pT • v3 is independent from centrality John C.-H. Chen

  8. vn vs geometrical anisotropy • Use en to describe geometrical anisotropy • vn follows the trend of en • Initial state anisotropy translate to final state momentum anisotropy John C.-H. Chen

  9. vn vs theory PRL 107 252301 (2011) • All theories describe v2 well • v3 adds in additional discrimination power • Data favors Glauber + h/s = 1/4p John C.-H. Chen

  10. Jet shape with higher vn modulated background subtraction 200GeV Au+Au 0-20%, inc. g-had. • When v3 modulation is included, the double peak structure in away-side disappears. John C.-H. Chen

  11. PID vn @ 200 GeV Au+Au • Mass ordering at low pT • Baryon/meson splitting at intermediate pT John C.-H. Chen

  12. NQS of PID vn • (vn/nqn/2) KET scaling in all vn • vn also shown in partonic level John C.-H. Chen

  13. PID v2 in higher pT • new detector TOFw and Aerogel enhance PID capability • Dedicated reaction plane detector • Extend to high pT (6 GeV/c) arxiv:1203.2644 John C.-H. Chen

  14. KET/nq scaling vs centrality • With finer centrality bins, the centrality dependence is clear • KET/nq scaling works at 0-10% • It starts breaking at 10-20% at KET/nq~ 1.0 GeV arxiv:1203.2644 John C.-H. Chen

  15. QCD phase transition • QGP is created at RHIC at 200 GeV • RHIC is flexible in beam energy • Down to 7.7 GeV • Can we find the critical point? • Any significant feature? John C.-H. Chen

  16. Beam energy dependence of vn • Various beam energy: 39, 62, 200 GeV • No significant beam energy dependence • Hydro dynamical behavior down to 39 GeV John C.-H. Chen

  17. PID v2 @ 62.4 and 39 GeV • NQS scaling still works at 39 GeV! John C.-H. Chen 17

  18. v2 measurement in broad energy range • At 7.7 GeV, the v2 value is significantly lower than 200 GeV • A possible transition between 7.7 and 39 GeV? John C.-H. Chen

  19. summary • vn has been measured systematically in PHENIX • vn is independent from beam energy between 39 GeV to 200 GeV • KET/nq scaling work on PID v2 from 39-200 GeV • But the KET/nq scaling breaks at large KET/nq in mid-central collisions John C.-H. Chen

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