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What do we learn from Azimuthal Anisotropy Measurements @ RHIC and the LHC Roy A. Lacey

What do we learn from Azimuthal Anisotropy Measurements @ RHIC and the LHC Roy A. Lacey Chemistry Dept., Stony Brook University. Take home m essage

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What do we learn from Azimuthal Anisotropy Measurements @ RHIC and the LHC Roy A. Lacey

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  1. What do we learn from Azimuthal Anisotropy Measurements @ RHIC andthe LHC Roy A. Lacey Chemistry Dept., Stony Brook University • Take homemessage • The scaling (pT, ε, R, ∆L, etc) properties of azimuthal anisotropy measurements at RHIC & the LHC, inform crucial mechanistic insights and constraints for characterization of the QGP? WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  2. Why RHIC and LHC Measurements? The energy density lever arm Lacey et. al, Phys.Rev.Lett.98:092301,2007 Energy scan • Relevant questions: • How do the transport coefficients • evolve with T? • Any indication for a change in • coupling close to To? • RHIC (0.2 TeV)  LHC (2.76 TeV) • Power law dependence (n ~ 0.2) • increase ~ 3.3 • Multiplicity density increase ~ 2.3 • <Temp> increase ~ 30% WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  3. Why Azimuthal Anisotropy Measurements? 3-4 < pT< 8-10 GeV/c Transition Region pT > 8 -10 GeV/c Jet suppression pT < 3 - 4 GeV/c Flow More suppression Less suppression Path length (∆L) driven Eccentricity driven & acoustic Flow and Jet suppression are linked to Geometry & the interactions in the QGP • This implies very specific scaling properties for flow and jet suppression (respectively), which can be tested experimentally • Scaling validation provide important insights, as well as straightforward probes of transport coefficients WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  4. Geometric Quantities for scaling Phys. Rev. C 81, 061901(R) (2010) B A arXiv:1203.3605 σx & σy RMS widths of density distribution • Geometric fluctuations included • Geometric quantities constrained by multiplicity density. WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  5. Scaling properties of high-pT anisotropy WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  6. More suppression Fixed Geometry Jet suppression Probe , Phys.Lett.B519:199-206,2001 Less suppression Modified jet Suppression (∆L) – pp yield unnecessary Suppression (L) For Radiative Energy loss: Path length (related to collision centrality) Jet suppression drives azimuthal anisotropy at high pTwith specific scaling properties on L, WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  7. High-pT v2 measurements - PHENIX Centrality dependence pT dependence Specific pT and centrality dependencies –Do they scale? WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  8. High-pT v2 measurements - CMS arXiv:1204.1850 Centrality dependence pT dependence Specific pT and centrality dependencies – Do they scale? WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  9. High-pT v2 scaling - LHC arXiv:1203.3605 v2 follows the pT dependence observed for jet quenching Note the expected inversion of the 1/√pT dependence WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  10. ∆L Scaling of high-pT v2 – LHC & RHIC arXiv:1203.3605 • Combined ∆L and 1/√pT scaling  single universal curve for v2 •  Constraint for εn WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  11. ∆L Scaling of high-pT v2 - RHIC • Combined ∆L and 1/√pT scaling  single universal curve for v2 •  Constraint for εn WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  12. Jet v2 scaling - LHC ATLAS 10-20% (z ~ .62) v2 for reconstructed Jets follows the pT dependence for jet quenching Similar magnitude and trend for Jet and hadron v2 after scaling WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  13. Jet suppression from high-pT v2 arXiv:1203.3605 • Jet suppression obtained directly from pT dependence of v2 • Compatible with the dominance of radiative energy loss ˆ αs and q Rv2 scales as 1/√pT , slopes encodes info on WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  14. pT scaling of Jet Quenching , Phys.Lett.B519:199-206,2001 arXiv:1202.5537 ˆ • RAA scales as 1/√pT ; slopes (SpT) encode info on αsand q • L and 1/√pT scaling  single universal curve • Compatible with the dominance of radiative energy loss WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  15. Extracted stopping power Phys.Rev.C80:051901,2009 arXiv:1202.5537 arXiv:1203.3605 • obtained from high-pT v2 and RAA [same αs]  similar • - medium produced in LHC collisions less opaque! • (note density increase from RHIC to LHC) ˆ ˆ qRHIC> qLHC qLHC Conclusion similar to those of Liao, Betz, Horowitz,  Stronger coupling near Tc? WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  16. Heavy quark suppression ˆ qLHC Consistent obtained WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  17. Scaling properties of low pT anisotropy WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  18. The Flow Probe Anisotropic p Idealized Geometry Isotropic p Yield(f) =2 v2cos[2(f-Y2] Crucial parameters Actual collision profiles are not smooth, due to fluctuations! Initial Geometry characterized by many shape harmonics (εn)  drive vn Acoustic viscous modulation of vn Staig & ShuryakarXiv:1008.3139 Initial eccentricity (and its attendant fluctuations) εndrive momentum anisotropy vnwith specific scaling properties WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  19. Acoustic Modulation εn drive momentum anisotropy vn with modulation Associate k with harmonic n Particle Distribution Scaling expectation Characteristic n2 viscous damping for harmonics  Crucial constraint for η/s Note that vn is related to v2 Characteristic centrality (1/R) viscous damping for a given harmonic  Crucial constraint for η/s WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  20. Is viscous hydrodynamic flow acoustic? Note:the hydrodynamic response to the initial geometry [alone] is included Characteristic n2 viscous damping and 1/(pT)αdependence  Crucial constraint for η/s and δf WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  21. vn(ψn) Measurements - ATLAS ATLAS-CONF-2011-074 High precision double differential Measurements are pervasive Do they scale? WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  22. Acoustic Scaling • Characteristic n2 viscous damping validated • Characteristic 1/(pT)αdependence of β validated • Constraint for η/s WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  23. Acoustic Scaling • Characteristic n2 viscous damping validated • Characteristic 1/(pT)αdependence of β validated • Constraint for η/s WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  24. Acoustic Scaling Straightforward constraint for eccentricity models WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  25. Acoustic Scaling Centrality – 5-50% • Characteristic 1/R viscous damping validated • A further constraint for η/s WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  26. Acoustic Scaling • Characteristic 1/R viscous damping validated • A further constraint for η/s WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  27. Flow increases from RHIC to LHC • Flow increases from RHIC to LHC • Sensitivity to EOS • increase in <cs> • Proton flow blueshifted [hydro prediction] • Role of radial flow • Role of hadronic re-scattering? WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  28. Constraint for η/s & δf arXiv:1301.0165 Phys.Rev. C80 (2009) 051901 • β Important constraint for η/s and δf <η/s> ~ 1/4π at RHIC; 25-30% increase for LHC WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  29. Summary Remarkable scaling have been observed for both Flow and Jet Quenching They lend profound mechanistic insights, as well as New constraints for estimatesof the transport and thermodynamic coefficients! What we learn? • RAA and high-pT azimuthal anisotropy stem from the same energy loss mechanism • Energy loss is dominantly radiative • RAA and anisotropy measurements give consistent estimates for <ˆq > • RAA for D’s give consistent estimates for <ˆq > • The QGP created in LHC collisions is less opaque than that produced at RHIC • Flow is acoustic • Flow is pressure driven • Obeys the dispersion relation for sound propagation • Flow is partonic • exhibits scaling • Constraints for: • initial geometry • small increase in η/s from RHIC (~ 1/4π) to LHC WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  30. End WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  31. Flow Saturates for 39 - 200 GeV • No sizeable beam energy dependence observed for v2 and v3 for each particle species • flow saturates for 39-200 GeV •  Soft EOS WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  32. Flow is partonic @ the LHC • Scaling for partonic flow validated after • accounting for proton blueshift • Larger partonic flow at the LHC WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  33. Is flow partonic? Note species dependence for all vn For partonic flow, quark number scaling expected  single curve for identified particle species vn WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  34. Acoustic Scaling • Increase of s2 for most central collisions is to be expected WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

  35. Flow @ RHIC and the LHC • Charge hadron flowsimilar @ RHIC & LHC • Multiplicity-weighted PIDed flow results reproduce inclusive charged hadron flow results at RHIC and LHC respectively WWND13 @ Squaw Valley, Feb. 2013, Roy A. Lacey, Stony Brook University

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