Two particle correlations with respect to higher harmonic plane in Au+Au 200 GeV collisions at RHIC-PHENIX Takahito Todoroki for the PHENIX Collaboration Univ. of Tsukuba, RIKEN Nishina Center JPS Annual Meeting 2012, Mar Gakuin 26 Mar 物理学会年次大会 1/10

Outline 1. Introduction Higher harmonic event plane(  n ) & flow(v n ) Backgrounds from v n in correlations v n subtracted correlations 2. Physics Motivation 3. Analysis Overview 4. Results      dependence 5. Summary 26 Mar 物理学会年次大会 2/10

   Previous picture; Assumed a “reaction plane” defined by impact parameter vector and beam axis vector Recent picture; Higher harmonic deformation due to fluctuations of collision geometry Deformation transferred to momentum space by collective expansion → higher harmonic flow(v n ) Higher harmonic event plane & flow Azimuth. distribution 26 Mar 物理学会年次大会 3/10

Backgrounds from v n in 2 particle correlations Backgrounds from v n v n (especially v 3 ) subtraction reduce “Ridge” and “Shoulder” v n subtractions help to see more “real” correlation shape 26 Mar Ridge 2< p T asso < p T trig GeV/C Phys. Rev. C 80, (2009) Ridge : near side long range  correlations Shoulder: double hump at away side of  correlations (also long in  ) Phys. Rev. C 78, (2008) ○:p+p ●: Au+Au Shoulder v 2 subtracted n=3 物理学会年次大会 4/10

v n subtracted correlations Shoulder is described by v n in central collisions Shoulder is still seen in mid-central collisions 26 Mar work in progress 物理学会年次大会 V 2 & V 4 (   ) subtracted V 2 & V 4 (   ) ZYAM subtracted V 2, V 3 & V 4 (   ) ZYAM subtracted 5/10

Physics Motivations v n subtracted correlations still show double- hump structure in ways side in mid-central collisions Average of jets flying to various direction in bulk Detailed survey of away side peaks Two particle correlations with trigger selection relative to   &    Modification of away side w.r.t.   &    Difference between   &   26 Mar 物理学会年次大会 ➊ ➋ ➌ ➍ ➄ ➅ ➆ ➇ ➊ ➋ ➌ ➍ ➄ ➅ ➆ ➇ 6/10

Analysis Overview v n measurements Forward Event Plane(RXN) - Charged Hadrons in mid-rapidity  To exclude autocorrelations by jet Selection of Trigger Directions Forward Event Plane(RXN)-Charged Hadron Trigger in mid-rapidity 2 particle charged hadron correlations in azimuth Mid-rapidity Trigger – Mid-rapidity Associate, p T : 2-4 & 1-2 [GeV/c] Subtract v n modulated backgrounds by ZYAM Method 26 Mar ZDC/SMD  dN/d  RXN in: 1.5<|  |<2.8 & out: 1.0<|  |<1.5 MPC: 3.1<|  |<3.7 BBC: 3.0<|  |<3.9 CNT: |  |<0.35 物理学会年次大会 PHENIX 7/10

   dependent correlations Two competitive effects Away-side peak shift to in/out of plane with in/out of plane trigger 26 Mar  2 R.P. shift to in-planeshift to out-of-plane  2 R.P. Trig. in-plane trigger case out-of-plane trigger case Flow subtracted yield is shown radially with base line. Trigger angle selection w.r.t.  2 for left(up) / right(down) 物理学会年次大会 200GeV Au+Au -> h-h, 20-50% (p T Trig =2~4, p T Asso =1~2GeV/c) v2, v3 & v4{  4 } subtraction PHENIX work in progress 8/10

   dependence before v n subtractions Subtraction shows no evident dependence Difference b/w   &      dominated by almond shape   dominated by fluctuations Would be related to differences 26 Mar out-of-plane In-plane ▪▫ : C2(data) -- : vn backgrounds 物理学会年次大会 9/10 Correlation Functions

Summary Measured two particle correlations with trigger selection relative to   &     dependent correlations show two competitive effects Away-side peak shift to in/out of plane with in/out of plane trigger   harmonic plane dependence wouldn’t be seen    dominated by almond shape   dominated by fluctuations 26 Mar 物理学会年次大会 10/10

Back Up Slides 26 Mar 物理学会年次大会 11/10

v 3 is comparable to v 2 at 0~10% v 2 rises up when centrality goes up, but v 3 hardly does v 4 {  4 } ~ 2 x v 4 {  2 } 26 Mar charged particle v n : |  |<0.35 event plane  n : |  |=1.0~2.8 PRL (ppg132) Charged hadron v n Centrality and p T dependences 物理学会年次大会 12/10

Degeneracy among models disentangled by v 3 v 3 seems to prefer low viscosity Glauber+  s  works better CGC-KLN+  s  failed v n provides more constraints to hydrodynamics calculations 26 Mar V2V2 V3V3 PRL (ppg132) B. Alver et. al., PRC82, (2010). B. Schenke et. al., PRL106, (2011). H. Petersen et. al., PRC82, (2010). (Event Plane Method) 物理学会年次大会 13/10

26 Mar 物理学会年次大会 14/10 QM2011, ATLAS

Fourier decomposition of flow subtracted correlations 26 Mar 物理学会年次大会 15/10

   dependence with v 2 & v 4    subtraction 26 Mar ➊➇➊➇ ➋➆➋➆ ➌➅➌➅ ➍➄➍➄ 物理学会年次大会 16/10

Trigger dependence relative to event plane 26 Mar  2 R.P. penetration dominancesurface dominance  2 R.P. Trig. Trigger angle selected 2-part. corr. data are plotted in polar coordinate by rotating  2 R.P. angle as X-axis. in-plane trigger case out-of-plane trigger case Flow subtracted yield is shown radially with base line. 200GeV Au+Au -> h-h, 20-50% (p T Trig =2~4, p T Asso =1~2GeV/c) v 2,v 4 {  2 } only subtraction PHENIX preliminary Two competing processes seen Trigger angle selection w.r.t.  2 separately for left(up) / right(down) 物理学会年次大会 RHIC-PHENIX Flow plenary S.E. 17/10

26 Mar /N trig dN pair /d  ➊➇➊➇➋➆➋➆ ➌➅➌➅ ➍➄➍➄  [rad] out-of-plane In-plane PHENIX Work in progress 200GeV Au+Au -> h-h, 20-50% (p T Trig =2~4, p T Asso =1~2GeV/c) v2,v3,v4{  4 } subtraction    dependence with v 2 & v 3 & v 4  subtraction 物理学会年次大会 18/10

26 Mar 物理学会年次大会 19/10