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Recent Flow Results From PHENIX

Recent Flow Results From PHENIX. Paul Stankus Oak Ridge National Lab WWND 9 April 2012. Initial Energy Deposit Hydro Evolution Freezeout / Hadronization. (This talk is presented in reverse order.). Note:.

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Recent Flow Results From PHENIX

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  1. Recent Flow Results From PHENIX Paul Stankus Oak Ridge National Lab WWND 9 April 2012

  2. Initial Energy Deposit Hydro Evolution Freezeout/Hadronization (This talk is presented in reverse order.)

  3. Note: Unless otherwise stated, all PHENIX anisotropy parameters shown here are of this type: nth-order anisotropy of hadrons at mid-rapidity nth-order event plane measured at high rapidity

  4. The Flowing Final State

  5. The data that initially led us to believe in hydrodynamics… … is now available in high-def. PHENIX Phys. Rev. Lett. 91, 182301 (2003) PHENIX arXiv:1203.2644, submitted to Phys Rev C in March 2012

  6. Preliminary results for v3 of identified hadrons indicates similar mass splitting, (nominally) consistent with hydro final state Much more detailed data on identified hadron v3 and v4 available soon!

  7. Most Central Mid-Central Possible “plateau” in v2 for higher pT protons in central, but not mid-central or peripheral collisions. Quark number scaling is better in KET/n than in pT/n, but still breaks for non-central collisions at about KET/n ~ 0.7 GeV and above. PHENIX arXiv:1203.2644

  8. The Evolution of Flow

  9. Signals from the interior? Let’s consider Direct Photons Previous PHENIX result strongly suggests that low-ishpT < 3 GeV/c direct photons in Au+Au are from a thermal, ie non-prompt source. They could encode a flow signal from an intermediate stage of the hydro evolution. PHENIX Phys. Rev. Lett. 104, 132301 (2010)

  10. Direct Photon v2 Inclusive γ, π0 Direct γ Technique: The v2 for a set of particle types is the number-weighted average of the v2 for each type, particularly decay vs direct. PHENIX arXiv:1105.4126 The Rγ ratio lets us partition the inclusive γ v2 into decay and direct components.

  11. Data Theory (mostly underpredicts) Au+Au 0-20% Chatterjee, et.al., Phys. Rev. Lett. 96, 202302 (2006) 20-40% MUSIC 20% Dion, et.al., Phys. Rev. C 84, 064901 (2011) PHENIX arXiv:1105.4126

  12. Saturation with Beam Energy Observe that v2, v3, v4 all saturate as √s enters RHIC regime π0 h± NB: A (uncontroversial) refutation of Hagedorn-style hadron gas models, where P/ε would decrease with beam energy.

  13. The η/sCottage Industry The PHENIX v3 results provide additional discrimination between flow scenarios. PHENIX Phys. Rev. Lett. 107, 252301 (2011)

  14. The Initial Deposition of Energy

  15. An eternal question: OR Smooth? Chunky?

  16. Chunky Smooth Initial Fluid Randomness Classical Hydro Hydro Final Fluid Randomness Particles

  17. ε3 ε2 Nagle, McCumber arXiv:1011.1853 Clear Clear ε2, ε3, ε4, ε5… v2,v4, v6 v3,v6, v9 Unclear! v2, v3, v4, v5… ?

  18. Signature of Initial Fluctuations Observe “normal” geometry dependence of v2, but almost no geometry dependence of v3 qualitatively consistent with v3 being driven mainly by initial-state transverse-plane fluctuations. v2 at pT=1.4 GeV/c v3 at pT=1.4 GeV/c PHENIX Phys. Rev. Lett. 107, 252301 (2011)

  19. Think outside the mid-plane Reaction Plane (x-z) x In the event-averaged geometry of a mid-central collision, we expect the ε3 orientations to be opposite at forward vs backward rapidities z y PR Cartoon of a mid-central A+A collision, with a 3-D initial state space superimposed

  20. In a marginally less cartoonish toy model, longitudinal momentum conservation “twists” the initial 3-D energy distribution, leading to oppositely-signed odd moments in the spatial anisotropies. Rapidity or Longitudinal Initial Hydro Space

  21. Event Plane Correlations North ϕ3 positively correlated with South ϕ3; indicates dominance of long-Δη fluctuations. PHENIX Phys. Rev. Lett. 107, 252301 (2011) No visible correlation between ϕ2 and ϕ3 event planes; direct test of fluctuation models PHENIX Forward 2π Detectors RXN: 1.0<|η|<2.8 MPC:3.1<|η|<3.7 BBC: 3.1<|η|<3.9

  22. Points to Take Home • PHENIX has a new wealth of flow (=low-pT anisotropy) results, including PID hadron v2to high pT, inclusive hadron v3 and v4, and direct photon v2 -- plus more coming soon! incl. PID v3, v4 • The hydrodynamical picture of the final-state is generally supported, but the hadronization process is still unclear; quark number scaling of v2 is broken above KET/n > 0.7 GeV • Low-pT direct photon v2 provides intermediate-stage information on how flow is built up; new ingredient, early flow? • Both higher-order moments and forward-backward event plane correlations indicate dominance of initial-state fluctuations in driving the flow; requires modeling fundamentally new physics

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