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Two particle correlation measurements at PHENIX

Two particle correlation measurements at PHENIX. Takahito Todoroki For the PHENIX Collaboration University of Tsukuba & RIKEN Nishina Center Hard Probes 2012 at Cagliari, Italy. Contents. Higher harmonic event plane and flow( v n ) Correlations with v n subtractions

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Two particle correlation measurements at PHENIX

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  1. Hard Probes 2012 Two particle correlation measurements at PHENIX TakahitoTodoroki For the PHENIX Collaboration University of Tsukuba & RIKEN Nishina Center Hard Probes 2012 at Cagliari, Italy

  2. Hard Probes 2012 Contents • Higher harmonic event plane and flow(vn) • Correlations with vnsubtractions • Correlations relative to event plane • At high and intermediate pT • Summary

  3. Hard Probes 2012 Motivations • Dissect possible interplay of hard-scattered partons & hot dense medium • To have definitive answer what remains in correlations after vn subtractions • To test path length dependence of parton energy loss via correlations relative to event plane

  4. Hard Probes 2012 Initial state of collisions Smooth picture Fluctuating picture • Initial collision geometry • Smooth to Fluctuating picture • Azimuthal particle distribution • vn(even){F2} only ⟶vn(even){Fn} + vn(odd){Fn} F2

  5. Hard Probes 2012 Charged Hadron vnat PHENIX PRL.107.252301 • v3 is comparable to v2 at 0~10% • v2 evolution as centrality increment, no evolution in v3 • v4{4} ~ 2 x v4{2} Charged particle vn : ||<0.35 Event plane n : ||=1.0~2.8

  6. Hard Probes 2012 Identified Particle vn • Mass dependence at low pT : Hydrodynamics • Baryon/Meson diff. at mid pT: Quark Coalescence

  7. Hard Probes 2012 vncontributions in correlations • Contributions from vn: • Ridge & Shoulder positions : Agree with v3 peaks • vn subtractions needed to get real jet correlations Phys. Rev. C 78, 014901 (2008) Phys. Rev. C 80, 064912 (2009) ○:p+p ●: Au+Au 2< pTasso < pTtrig GeV/C v2 subtracted Ridge Shoulder n=3 n=3

  8. vn reproduce Ridge & Shoulder at 0-5% Hard Probes 2012 Correlations with Dh gap QM’11 J. Jia ATLAS Flow Plenary ￮ measured correlations vn with EP Method Track at |h|<2.5 with EP from full FCAL 3.3<|h|<4.8 No Flow Subtraction Pb+Pb 2.76TeV vn with 2Par. Cor Method Charged particle pair with large rapidity gap e.g. |Dh|>2

  9. Hard Probes 2012 Correlations without Dh gap • Away side shoulders are almost gone in most-central collisions 0-20% Au+Au 200GeV 0-20% PHENIX PRELIMINARY Incl.g - hadron 2-3x1-2 GeV/c |Dh|<0.7

  10. Hard Probes 2012 Correlations up to centrality 50% • Away side shoulders • Canceled in most-central collisions : 0-10% • Remain in mid-central collisions : 20-50% • To Do : Include v1 term to vn modulation for definitive answer V2, V3 & V4(F4) modulation by ZYAM method

  11. Hard Probes 2012 Correlations relative to event plane • Control parton path length • By selecting trigger relative to forward event plane • Reduce autocorrelations of jet itself Mid rapidity Forward rapidity ft fs Df Fn fa

  12. Hard Probes 2012 High pT range • Near side yield : No suppression • Away side yield : Monotonic decrease v2 & v4{F2} modulated Au+Au 200GeV 20-60% PRC.84.024904 IAA = YAA/Ypp Short path length Long path length

  13. Hard Probes 2012 Intermediate pTrange • Constant suppression of back-to-back jet • Two competitive effects seen out-of-plane trigger case in-plane trigger case PHENIX preliminary Trig. Flow subtracted yield is shown radially with base line. Au+Au 200GeV 20-50% h-h :2-4x1-2GeV/c v2 & v4{F2} modulated Trig. 2 R.P. 2 R.P. Trig. surface dominance penetration dominance Trig.

  14. Hard Probes 2012 Summary • Higher harmonic flow vnhas been measured • By vn modulation to correlations, • Shoulders almost gone in most-central collisions • Shoulders remain in mid-central collisions • Correlations relative to event plane • Monotonic away side suppression at high pT • Constant suppression of di-jet & Two competitive effects at intermediate pT • Fully vn modulated analyses are in progress

  15. Hard Probes 2012 Backup Slides

  16. Hard Probes 2012 Fi - Fj correlations PRL.107.252301

  17. Hard Probes 2012 vnvia event plane method CNT: |h|<0.35 • Mid rapidity particle anisotropy relative to forward event planes RXN RXN in: 1.5<|h|<2.8 & out: 1.0<|h|<1.5 dN/d MPC: 3.1<|h|<3.7 BBC: 3.0<|h|<3.9 2cm Pb converter in front ZDC/SMD -5 0 5 

  18. Hard Probes 2012 Degeneracy among models disentangled by v3 • v3 seems to prefer low viscosity • Glauber+4ph/s =1 works better • CGC-KLN+4ph/s =2 failed • More constraints to hydrodynamics calculations V2 (Event Plane Method) V3 PRL.107.252301 (ppg132) B. Alver et. al., PRC82, 034913(2010). B. Schenke et. al., PRL106, 042301(2011). H. Petersen et. al., PRC82, 041901(2010).

  19. Hard Probes 2012 QM’11 J. Jia ATLAS Flow Plenary

  20. Hard Probes 2012 Scaling property of v2

  21. Hard Probes 2012 Scaling property of vn • vn(KET/nq)/nqfailed on v3, v4 & v4{F2} • vn(KET/nq)/nqn/2: need correction power

  22. Hard Probes 2012 Fourier decomposition of flow subtracted correlations

  23. Hard Probes 2012 Correlations relative to F3

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