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Inter- collaboration Comparison of Differential Elliptic Flow Data at RHIC

Inter- collaboration Comparison of Differential Elliptic Flow Data at RHIC. Arkadij Taranenko. Nuclear Chemistry Group SUNY Stony Brook, USA. Many thanks to the organizers and R.A. Lacey, H. Masui, A. Tang , S. Huang, R. Nouicer and many others.

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Inter- collaboration Comparison of Differential Elliptic Flow Data at RHIC

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  1. Inter- collaboration Comparison of Differential Elliptic Flow Data at RHIC Arkadij Taranenko Nuclear Chemistry Group SUNY Stony Brook, USA Many thanks to the organizers and R.A. Lacey, H. Masui, A. Tang , S. Huang, R. Nouicer and many others. Joint CATHIE / TECHQM Workshop, December 14-18 , 2009, BNL

  2. Ten Years of Elliptic Flow Measurements at RHIC P. Romatschke and U. Romatschke, Phys. Rev. Lett. 99:172301, 2007 • Largest amount of flow data in the history of HIC are collected by four RHIC Collaborations. • Do we understand the measurements enough and ready for quantitative comparison with models? • [flow vs non-flow, fluctuations, so many methods, … ]: 20-30% uncertainty in v2 may lead to a huge uncertainty in the extracted η/s value Luck of detailed quantitative comparison of results from differential flow measurements between RHIC Collaborations .. This talk! Do we have qualitative agreement ? Answer is : ???

  3. Centrality dependence of Elliptic Flow: Breaking of Eccentricity Scaling at RHIC H. Masui JPS/APS meeting 2009 A. Tang , QM2009, arXiv:0907.4513 R. Lacey et al, arXiv:0905.4368 Do we have qualitative agreement ? Answer is : YES!!!

  4. Transverse Kinetic Energy + NCQ scaling at RHIC Phenix: Phys. Rev.Lett. 98,162301 (2007) Nucl.Phys.A830:187C-190C,2009 Au+Au Detailed study of KET / NCQ scaling by STAR/PHENIX:nucl-ex/0604011; PoS CFRNC2006:021,2006; Phys. Rev.Lett. 98,162301 (2007); Phys.Rev.C75:054906,2007; J.Phys.G34:S1069-1072,2007; Phys. Rev. Lett. 99, 052301 (2007) ; Phys.Rev.C77:054901,2008; Nucl.Phys.A830:183C-186C,2009; Nucl.Phys.A830:187C-190C,2009,…… The only difference is KET for PHENIX and (mT – m 0) for STAR Do we have qualitative agreement ? Answer is : YES!!!

  5. The break of KET / NCQ scaling at high pT Phenix: QM 2008, DNP 2008, QM 2009 STAR: QM 2009 J.Phys.G35:104105,2008,J.Phys.G36:064061,2009 Nucl.Phys.A830:673C-680C,2009 Do we have qualitative agreement ? Answer is : YES!!!

  6. V4 : A Small, But Sensitive Observable For Heavy Ion Collisions PHENIX: QM 08, WWND 08, DNP 08, QM 09 STAR: WWND 09, QM 2009 J.Phys.G35:104105,2008,J.Phys.G36:064061,2009 STAR preliminary STAR preliminary V4 ~ k * (V22) – very small signal Do we have qualitative agreement ? Answer is : YES!!!

  7. Centrality dependence of V4 / (V22) ratio STAR/PHENIX C. Gombeaud, J-Y Ollitrault [arXiv:0907.4664] STAR/PHENIX Preliminary data for charged hadrons: pT = 1.0-2.7 GeV/c for STAR pT=1.0-2.4 GeV/c for PHENIX – looks very close The potential difference in methods for event plane resolution [ for v4 measurements ] may explain the residual difference in v4/(v22) ratios What about V6 ~ k * (V23) – very-very small signal …..???

  8. Inter- collaboration Comparisons of Differential Elliptic Flow Data at RHIC • Comparisons madeonly for differential measurements: v2 (pT ,centrality) • First : comparison for the same methods --- “apples to apples” instead of “apples to oranges” • Method of comparison: Ratio of v2 (PHOBOS or STAR) / v2 (PHENIX) as a function of pT for different bins in collision centrality. Today: v2 (p T ,centrality) for charged hadrons from Au+Au at 200 GeV Phys. Rev. C 72 (2005) 14904 Do we have quantitative agreement ? Answer is : ???

  9. Elliptic Flow Measurements V2 (pT , centrality) in PHOBOS/STAR/PHENIX TPC FTPC FTPC ZDC/SMD ZDC/SMD η |η| < 1.3 2.5 <|η|< 4.0 |η| > 6.3 STAR Central Arms BBC/MPC ZDC/SMD ZDC/SMD BBC/MPC RXN RXN 1.0<|η|<2.8 |η| > 6.6 PHENIX |η|<0.35 3.1<|η|<3.7 η 3.1<|η|<3.9 EP EP PHOBOS η η = 0-1.6 2.05<|η|<3.2

  10. Reference for comparison: v2(pT, centrality) from PHENIX Central Arms Au+Au at 200 GeV, Run 2007 PHENIX Preliminary New RXN detector RXN RXN arXiv:0905.4368 BBC/MPC BBC/MPC Consistent results via 5 separate measurements of v2 and v4 in the same experiment Event planes 2020/1/2

  11. 1) Reference for comparison: PHENIX v2(pT, centrality) measured with respect to RXN event plane [1.0 <|η|<2.8] Central Arms New RXN detector RXN RXN BBC/MPC RXN: 1.0 < |η| < 2.8 Centrality and pT chosen to match other experiments 2020/1/2

  12. 2) Reference for comparison: PHENIX v2(pT, centrality) measured with respect to MPC event plane [3.1 <|η|<3.7] Central Arms RXN RXN BBC/MPC MPC: 3.1 < |η| < 3.7 Muon Piston Calorimeters (MPCs)- PbWO4 based electromagnetic calorimeters with 2π azimuthal acceptance Similar pT and centrality 2020/1/2

  13. Comparison of differential v2(pT, centrality): PHOBOS/PHENIX EP: 1.0<|η|<2.8 from PHOBOS QM06 proc. J. Phys. G34 S887 (2007)‏ η EP{1} EP{2} EP: 3.1<|η|<3.7 PHOBOS EP: 2.05<|η|<3.2 Overall good agreement between differential flow measurements

  14. Elliptic Flow Measurements V2 (pT , centrality) in STAR/PHENIX TPC FTPC FTPC ZDC/SMD ZDC/SMD η |η| < 1.3 2.5 <|η|< 4.0 |η| > 6.3 STAR comparison Central Arms BBC/MPC ZDC/SMD ZDC/SMD BBC/MPC RXN RXN η 1.0<|η|<2.8 |η| > 6.6 PHENIX |η|<0.35 3.1<|η|<3.7 3.1<|η|<3.9

  15. Differential v2(pT, centrality): STAR [Central TPC |η|<1.0] V2{EP} – standard event plane method Phys.Rev. C72(2005) 14904‏ V2{EP2} – modified event plane method: all subevent particles in |Δη|<0.5 around highest pT particle in the event are excluded from event-plane determination. Ratio:V2{EP} / V2{EP2} > 1 at high pT

  16. Comparison v2(pT, centrality): STAR [Central TPC |η|<1.0] / PHENIX V2{EP} – standard EP method V2{EP2} – modified EP method

  17. Comparison v2(pT, centrality): STAR [Central TPC |η|<1.0] / PHENIX V2{EP} – standard EP method V2{EP2} – modified EP method For 0-20% central collisions STAR V2 > PHENIX V2 :do we have the same centrality definition between experiments?

  18. Do we have the same centrality definition? 1% shift 2% shift V2{EP2} – modified EP method (STAR) Lets assume centrality shift between PHENIX/STAR : results are for 1% and 2% shift.

  19. Comparison v2(pT, centrality): with STAR two particle cumulant results Two particle cumulant results from STAR + subtraction of non-flow using p+p coll. Two particle cumulant results from STAR Reasonable agreement with two-particle cumulant results after Subtraction of correlations from p+p collisions [ low pt region?]

  20. Comparison v2(pT, centrality) PHENIX: BBC vs ZDC/SMD event plane |η|<0.35 BBC ZDC/SMD Phys. Rev. C 80, 024909 (2009) η |η|>6.6 3.1<|η|<3.9 Ratio R=V2{ZDC/SMD}/V2{BBC} does not depends on pT[ checked for 0-10,10-20,20-30,30-40,40-50,20-60%] V2{ZDC/SMD} < V2{BBC} – different fluctuations ? Very large systematic errors for V2{ZDC/SMD} measurements – can we reduce them ? H. Masui, Eur.Phys.J.C62:169-173,2009 Good agreement with prelim. STAR V2 results from ZDC/SMD analysis

  21. Differential v2(pT): STAR [Central TPC]: Multi-particle methods Phys. Rev. Lett. 93 (2004) 252301 Phys. Rev. C 77 (2008) 54901 V2{2} V2{4} V2{LYZ} Question for STAR:Why V2/V2{EP} has pT dependence for 4p cumulant method, but it is flat as a function of pT for LYZ method ? V2{4} – four particle cumulant method V2{LYZ} – Lee Yang Zero method

  22. Differential v2(pT): Comparison with STAR Multi-particle methods 4p cumulant method Lee-Yang-Zeros Method Ratio V2 {STAR} / V2{PHENIX EP} < 1.0 for 4p cumulant and LYZ method . LYZ : Lee-Yang-Zeros Method

  23. Summary • There is good qualitative agreement between STAR/PHENIX for v2 and v4 scaling results. • Reasonable quantitative agreement found for event plane results for V2 (pT, centrality ) for charged hadrons from Au+Au collisions at 200 GeV: • PHENIX/PHOBOS and PHENIX/STAR [for mid-central collisions]. • The difference in central collisions can be explained by a small difference in centrality definition ? • The differences with STAR multi-particle methods is constant as a function of pT and can be attributed for fluctuations? • Plans: comparison with STAR FTPC are necessary for better understanding of event plane results. Comparison for PID results, • Different colliding systems and beam energies. ArkadijTaranenko, QM2009 2020/1/2

  24. Backup Slides

  25. Comparison of integral flow results from different methods … STAR preliminary QM 2006 PHENIX Preliminary QM 2009 STAR preliminary ???? QM 2009

  26. Comparison of differential flow results from the same method may help… C. Gombeaud, J-Y Ollitrault [arXiv:0907.4664] Sometimes we do not see big picture ….. STAR/PHENIX Preliminary data for charged hadrons: pT = 1.0-2.7 GeV/c for STAR and pT=1.0-2.4 GeV/c for PHENIX – looks very close The potential difference in methods for event plane resolution [ for v4 measurements ] may explain the residual difference in v4/(v22) ratios

  27. Comparison v2(pT, centrality): STAR/PHENIX: Effect of 1% shift in centrality V2{EP2} – modified EP method Centrality shift 1% Centrality shift 1% Do we have the same centrality definition between experiments?

  28. Comparison of differential flow results from the same method may help…

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