Takahito Todoroki for the PHENIX Collaboration University of Tsukuba & RIKEN Nishina Center

1. Two particle correlation measurements with respect to higher harmonicevent planes at PHENIX TakahitoTodoroki for the PHENIX Collaboration University of Tsukuba & RIKEN Nishina Center Quark Matter 2012, Washington D.C.,U.S.A. Quark Matter 2012

2. Motivations • Dissect possible interplay between hard-scattered partons and hot dense medium • Have definitive answer on what remains in correlations after vn background subtractions • Test path length dependence of parton energy loss via correlations relative to higher harmonic event planes Quark Matter 2012

3. Correlations and flow harmonics vn at PHENIX • Two particle correlations • Mid-rapidity hadrons, without h gap where jet contribution remains • Event plane Yn : RXN at forward h • vn measurements • Trigger direction w.r.t. EP in sub-divided correlations • vn via EP method Quark Matter 2012

4. Charged Hadron vn and background shape in correlations • Input to vn background subtractions • Flow background shape PRL.107.252301 Charged particle vn : ||<0.35 Event plane n : ||=1.0~2.8 Quark Matter 2012

5. Correlations in fine centrality steps with variousvn background subtractions by ZYAM Quark Matter 2012

6. Impact of v3to away side residual • v3largely reduce away-side shoulder • Small residual at away side in most central • Double hump almost gone in mid central , ZYAM Quark Matter 2012

7. Sensitivity of away-side residual to v4 • v4(Y2) doesn’t change away-side trends in most & mid-central • v4(Y4) removes away-side residual in mid-central but reproduce double hump in mid-central • Away-side residual shape depends on treatment of v4 , ZYAM Quark Matter 2012

8. v1 estimations by two methods • Event plane method Au+Au 200GeV • Two particle correlation method • Correlations with |Dh|>0.5 • Fourier decomposition Au+Au 200GeV v1 ~ 0.01 v1 ~ 0.063 v1 ~ 0.054 v1 ~ 0.005 • Two methods provide two different amplitude v1 Quark Matter 2012

9. vn (n=1,2,3,4) subtracted correlations • Inclusion of v1 term to vn background subtractions doesn’t change away side residual so much • Confirmed with two v1 have different amplitude , ZYAM Quark Matter 2012

10. Correlations relative to Y2 & Y3 • Rapidity gap between trigger and event planes • Reduce autocorrelations of jet itself • Control parton path length (mainly Y2) • Sensitivity of correlations to different harmonic event planes ft fs Df Mid rapidity Forward rapidity Yn fa Quark Matter 2012

11. Parton path length in Left/Right correlations • Left/Right trigger selection relative to event plane results innon-uniform path length at away-side • Modification expected in away-side as Left/Rightasymmetry arXiv:0903.3263 Near Side C(Df) Shorter path length EP Longer path length Away Side Quark Matter 2012

12. Correlations relative to Y2 • Clear Y2dependence of correlation shape • Left/Right asymmetry observed • More pronounced in mid-central collisions All results in back up slides Out-of-plane In-plane 0-10% 40-50% Quark Matter 2012

13. Interpretation of Left/Right Asymmetry • What is the implication of observed Left/Right asymmetry? • Path length dependence of jet modification? • Flow function has left/right asymmetry • Subtracted results has ambiguity in flow subtractions? • Additional jet-flow coupling? ○ : Raw data correlations - : Flow function by v2 v3 v4(Y4) with <cos4(Y2-Y4)>=v4(Y2) /v4(Y4) ➊➇ ➋➆ ➌➅ ➍➄ C(Df) Quark Matter 2012

14. Correlations relative to Y3 All results in back up slides • Same analysis method followed as in Y2dependent correlations • Y3dependent correlations are independent of trigger within systematics • Discrepancy between Left/Rightcorrelations are consistent within systematics ➇ ➆ ➅ ➄ ➊➇ ➋➆ ➌➅ ➍➄ ➍ ➌ ➋ ➊ 20-30% Quark Matter 2012

15. Summary • Correlations with vn background subtractions • Treatment of v4 is crucial for away-side residual shapes at intermediate pT • Effect of v1 is not so significant in symmetric collision systems at mid-rapidity • Correlations relative to higher harmonic eventplanes • On correlation shapes depending on Yn • Y2 dependent correlations show clear trigger dependence • Y3dependent correlations are independent of trigger direction within systematics • Further understanding of reaction plane dependence & Left/Right asymmetry will inform interpretation of inclusive correlations Quark Matter 2012

16. Quark Matter 2012

17. Backup Slides Quark Matter 2012

18. Yn resolutions &Yi - Yjcorrelations PRL.107.252301 n=2 RXN n=3 RXN n=4 RXN n=2 MPC n=3 MPC PHENIX Preliminary n = <cosn(n(meas.) - n(true))> centrality (%) Quark Matter 2012

19. v1 by event plane method • Event plane method • Inclusive measurements of v1 over h compensate signal due to opposite sign of v1 in forward/backward rapidity • Flipping of Y1 and f to keep v1 signal Au+Au 200GeV Quark Matter 2012

20. v1 by two particle correlation method • Two particle correlation method • Correlations with |Dh|>0.5 • Decomposed by Fourier fitting & extract v1tr*v1as Au+Au 200GeV v1 ~ 0.063 v1 ~ 0.054 Quark Matter 2012

21. Correlations relative to Y2 & Y3,0-10% ➊➇ ➋➆ ➌➅ ➍➄ ➊➇ ➋➆ ➌➅ ➍➄ Quark Matter 2012

22. Correlations relative to Y2 & Y310-20% ➊➇ ➋➆ ➌➅ ➊➇ ➋➆ ➍➄ ➌➅ ➍➄ ➊➇ ➋➆ ➌➅ ➍➄ ➊➇ ➋➆ ➌➅ ➍➄ Quark Matter 2012

23. Correlations relative to Y2 & Y320-30% ➊➇ ➋➆ ➌➅ ➊➇ ➋➆ ➍➄ ➌➅ ➍➄ ➊➇ ➋➆ ➌➅ ➍➄ ➊➇ ➋➆ ➌➅ ➍➄ Quark Matter 2012

24. Correlations relative to Y2 & Y330-40% ➊➇ ➋➆ ➌➅ ➊➇ ➋➆ ➍➄ ➌➅ ➍➄ ➊➇ ➋➆ ➌➅ ➍➄ ➊➇ ➋➆ ➌➅ ➍➄ Quark Matter 2012

25. Correlations relative to Y2 & Y3,40-50% ➊➇ ➋➆ ➌➅ ➍➄ ➊➇ ➋➆ ➌➅ ➍➄ Quark Matter 2012