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Conical Emission in Heavy-Ion Collisions

Conical Emission in Heavy-Ion Collisions. Jason Glyndwr Ulery Purdue University 8 February 2008 Quark Matter 2008. Outline. Motivation Theory Mach-cone shock waves Čerenkov gluon radiation Experiment PHENIX STAR CERES Summary Future. Motivation. STAR PRL 95 152301 Ulery QM05.

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Conical Emission in Heavy-Ion Collisions

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  1. Conical Emission in Heavy-Ion Collisions Jason Glyndwr Ulery Purdue University 8 February 2008 Quark Matter 2008

  2. Outline • Motivation • Theory • Mach-cone shock waves • Čerenkov gluon radiation • Experiment • PHENIX • STAR • CERES • Summary • Future Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  3. Motivation STAR PRL 95 152301 Ulery QM05 • Mach-cone in HIC first introduced in 1970s by Hofmann, Stöcker, Heinz, Scheid and Greiner. • Away-side structure in 2-particle correlations renewed interest. • Conical emission is a possible explanation for shape: • Mach-cone shock waves • Čerenkov gluon radiation • Other explanations suggested: • Large angle gluon radiation • Defected jets • deflected by radial flow • path-length dependent energy loss  Au+Au PHENIX PRL 97 052301  0 /2 CERES Kniege QM06 Pb+Au 0-5%  Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  4. Conical Emission • Mach-cone: • Shock waves excited by a supersonic parton. • Can be produced in different theories: • Hydrodynamics • H. Stöcker et al. (Nucl.Phys.A750:121,2005) • J. Casalderra-Solana et. al. (Nucl.Phys.A774:577,2006) • T. Renk & J. Ruppert (Phys.Rev.C73:011901,(2006)) • Colored plasma • J. Ruppert & B. Müller (Phys.Lett.B618:123,2005) • AdS/CFT • S. Gubser, S. Pufu, A. Yarom. (arXiv:0706.4307v1, 2007) • Čerenkov Gluon Radiation: • Radiation of gluons by a superluminal parton. • I.M. Dremin (Nucl. Phys. A750: 233, 2006) • V. Koch et. al. (Phys. ReV. Lett. 96, 172302, 2006) • Parton Cascade • G. L. Ma et. al. (Phys. Lett. B647, 122, 2007) References are only a small subset of those existing. Apologies to those not included. Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  5. Čerenkov Gluon Radiation • Gluons radiated by superluminal partons. • Angle is dependent on emitted momentum. Čerenkov angle vs emitted particle momentum Koch, Majumder, Wang PRL 96 172302 (2006) p (GeV/c) Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  6. Mach-Cone M M Trigger Away-side • Mach angle depends on speed of sound in medium • T dependent • Angle independent of associated pT. PNJL Model Mikherjee, Mustafa, Ray Phys. Rev. D75 (2007) 094015 Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  7. Hydrodynamic Mach-Cone Cloud formed by a plane breaking the sound barrier. • Energy radiated from the parton is deposited in collective hydrodynamic modes. • Strength of the correlation dependent on source term which is not fundamentally derived. • Similar to jet creating a sonic boom in air. Betz QM08 Talks by B. Betz and B. Müller Session XIII Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  8. Colored Modes Parallel • QCD analog of charged particle in plasma from QED. • Mach-cone is longitudinal modes excited in quantum plasma by a supersonic parton. • Colored sound. • Černkov gluon radiation is the transverse mode excited by superluminal parton in the plasma. Current Density Perpendicular J. Ruppert & B. Müller, Phys. Lett. B618 (2005) 123 Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  9. Ads/CFT Poynting Vector • Mach cone with strong diffusion wake from heavy quarks. • Mach cone with no diffusion wake for quarkonium. • No need to add a source term. • Done is infinitely massive limit. Gubser, Pufu, Yarom arXiv:0706.4307v1 (2007) Bullet at 2.45cs diffusion wake shock-wave Talk by Noronha Session IV Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  10. Azimuthal 3-Particle Correlations near near near Medium Medium Medium away away away di-jets deflected jets Conical Emission Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  11. Parton Cascade background subtracted 3-particle correlation signal G.L.Ma QM06 • Simulated data analyzed from AMPT parton cascade model. • Backgrounds subtracted through event mixing in similar method to real data. • Conical emission signal seen. • What is the mechanism that produces the signal? Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  12. Mach-Cone and Flow Renk, Ruppert, Phys. Lett. B646 19 (2007) • Rapidity distribution and longitudinal flow affects theobserved angle and width. • Transverse flow affects shape of 3-particle correlation. • signal at ~1 GeV/c ~9x larger if flow and shockwave aligned than if perpendicular. Renk, Ruppert, Phys. Rev. C76, 014908 (2007) Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  13. Detectors • PHENIX has 2 900 wedges in azimuth. • STAR and CERES have full 3600 azimuthal acceptance. STAR at RHIC CERES at SPS PHENIX at RHIC Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  14. PHENIX Analysis Poster 243 Ajitanand Trigger Near-Side Plane Normal to Trigger * * * * *= Ajitanand HP06, IWCF’06 • Polar coordinate system relative to trigger particle direction. • Natural coordinate system if jets are back-to-back in both  and . • * is angle from trigger. • * the angle between the two associated particles projected onto plane defined by trigger. • 2.5<pTTrig<4 GeV/c • 1<pTAssoc<2.5 GeV/c Au+Au 10-20 % Near Side Away Side Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  15. PHENIX Simulations Poster 243 Ajitanand Simulated Mach Cone *=0 Ajitanand HP06, IWCF’06 Simulations with PHENIX acceptance. Simulated Deflected jet * * Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  16. PHENIX Results Poster 243 Ajitanand * Projections v2 subtracted 2-particle dominated 2-particle dominated v2 and 2-particle subtracted Deflected Mach-cone PHENIX PRL 97, 052301 (2006) • 3-particle/2-particle ~ 1/3, very large • Residual background? Ajitanand HP06, IWCF’06 v2 subtracted Au+Au 10-20% • Shape consistent with simulated mach-cone. Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  17. STAR Poster: 36 Ma Ulery QM05, QM06 (poster) 2-Particle Hard-Soft Raw • In - space. • 3<pTTrig<4 GeV/c and 1<pTAssoc<2 GeV/c (except as noted) • 2-Particle background normalized such that background subtracted 3-particle signal is ZYAM. • Hard-soft background removes instances where 1 associated particle is correlated with trigger. Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  18. STAR Poster: 36 Ma Ulery QM05, QM06 (poster) v2(T) v2(1,2) Soft-Soft v4(T)v4(1,2)+v2(T,1,2)v2(1,2,T)v4(2,T,1) • Soft-soft is the background from both associated particles independent of the trigger. • Background from the correlations of trigger and associated particles to reaction-plane are added from flow measurements. Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  19. STAR Results Poster: 36 Ma Ulery QM05, QM06 (poster) d+Au Cu+Cu 0-10% pp Au+Au 10-30% Au+Au 0-12% Au+Au 50-80% Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  20. STAR Projections and Angle Talk: Mohanty Conical emission peaks ZDC 0-12% Au+Au shows significant peaks in off-diagonal projection at: 1.38 ± 0.02 (stat.) ± 0.06 (sys.) radians Ulery QM05, QM06 (poster) Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  21. STAR Associated PT Dependence Poster: 36 Ma 2<pTAssoc<3 0.5<pTAssoc<0.75 1<pTAssoc<1.5 • No significant pT dependence of observed emission angle. • Consistent with Mach-cone • Inconsistent with simple Čerenkov radiation Ulery QM05, QM06 (poster) Poster: P36 Ma Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  22. CERES Poster 251 Appelshaeuser, Kniege, Plokson Kniege QM06, ISMD07 Raw Hard-Soft Soft-Soft Trigger Flow (v2v2) • 2.5<pTTrig<4.0 GeV/c • 1.0<pTAssoc<2.5 GeV/c • Background subtraction method similar to STAR. • axis ranges are different from STAR preliminary preliminary preliminary Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  23. CERES Results Poster 251 Appelshaeuser, Kniege, Plokson Kniege QM06, ISMD07 • Conical emission peaks are seen. h++ and h-- hhh h+- and h-+ preliminary preliminary Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  24. Summary • Broadened and double-peaked away-side structure in 2-particle correlations. • Can be explained by conical emission or other physics mechanisms. • Mach-cone • Čerenkov gluon radion • PHENIX • shape consistent with Mach-cone simulation. • residual background? • STAR • Evidence of conical emission of correlated hadrons at an observed angle of 1.38 radians • pT independence of the angle suggests Mach-cone emission • CERES • peaks consistent with conical emission • With the aid of theoretical models the extracted angle my provide information on the speed of sound of the medium and the equation of state. Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  25. Future Prospects • New data and detectors will allow for: • Higher statistics will allow for systematic studies of both trigger and associated pT. • Helped by increased jet production at LHC • Identified particle results: • Mach-cone emission should have a mass dependence in correlation strength • Full azimuthal TOF detectors ALICE and STAR (upgrade) will provide good PID for these analyses. • Possible change in angle between SPS, RHIC, and LHC. • Different initial temperatures • Many theoretical investigations have been carried out. • More work is needed to understand what the data tells us about cs and EOS. Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  26. Parallel Session xiii • Medium Response to Jets & Mach Cone Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  27. Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  28. Backup Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  29. Centrality Dependence Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  30. STAR Cumulant Pruneau (STAR) QM’06 • Done in - space where =Trigger-Associated • Trigger particles of 3<pT<4 GeV/c. • Associated particles of 1<pT<2 GeV/c. • Mathematically Defined. • Measures all three-particle correlations. C3(12,13) = 3(12,13) - 2(12)1(3) – 2(13)1(2) - 2(12- 13)1(1) - 2 1(1)1(2)1(3) Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  31. STAR Cumulant Results • Non-zero 3-particle correlation. • Results contain all possible 3-particle correlations; jet, flow and jet  flow. • Further interpretation requires model assumptions. • Non-Poisson fluctuations can leave residual 2-particle correlations. Au+Au 50-80% Au+Au 10-30% Au+Au 0-10% Pruneau (STAR) QM’06 Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  32. STAR With Identified Associated Poster: 36 Ma 2.5<pTTrig<10 GeV/c 0.7<pTAssoc<1.4 GeV/c • Comparison of correlation with identified proton and pion associated. • Hint of wider peaks for h-pp. Jason Glyndwr Ulery - Purdue University Quark Matter 2008

  33. Cone Signal • 1.2 pairs/trigger in 3-particle off-diagonal strength ~0.6 (off-diagonal)x4 (peaks)x(0.7x0.7) • 0.7 particles/trigger ~0.5 (away-side)x2(peaks)x0.7 • (0.7)2=1.2 (assume Poison distribution) • ~40% (% of triggers with a cone in the acceptance). • ~2~(0.7/0.4) cone particles per event with cone in acceptance. Jason Glyndwr Ulery - Purdue University Quark Matter 2008

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