Conical Correlations in Heavy-Ion Collisions

1. Conical Correlations inHeavy-Ion Collisions Barbara Betz Thanks to: Miklos Gyulassy, Jorge Noronha, Dirk Rischke, Giorgio Torrieri Phys. Rev. C 79, 034902 (2009),Phys. Lett. B 675, 340 (2009), Nucl. Phys. A 830, 777c (2009), arXiv:1005.5461

2. Conical Correlations in HIC • What are „conical correlations in heavy-ion collisions“? Correlations revealing the creation of Mach cones??? What could they tell us about the medium created? Experiment: Review on experimental studies Theoretical approaches: Jets & hydrodynamics Different energy-loss mechanisms Fluctuating initial conditions, v3 (carryingcoalsto Newcastle) Conclusions and Outlook Deflection of wakes due to transverse flow „Conical“ signal Why we need to study heavy-flavor tagged jets

3. HIC Facilities • RHIC, BNL: 2000 – … • p+p, d+Au, Cu+Cu, Au+Au • LHC, CERN: 2008/9 - … • p+p, Pb+Pb • FAIR, GSI: ~2016 - … • acceleratesionsfrom p to U FAIR RHIC LHC hadronic phase and freeze-out initial state expanding fireball pre-equilibrium hadronization S. Bass, Talk Quark Matter 2001

4. 2 Major RHIC Results

5. Fluid-like Medium Medium behaves like an almost ideal fluid BNL press release, April 18 2005. „dust“ fluid Particles don‘t interact, expansion independent of initial shape Particles interact, expansion determined by density gradient • Reproducing the elliptic flow v2 P. Romatschke and U. Romatschke, Phys. Rev. Lett. 99, 172301 (2007) Data can be described by hydrodynamics with small

6. 4 < pTtrigger < 6 GeV/c pTassoc > 2 GeV/c STAR, Phys. Rev. Lett. 91 (2003) 072304 Jet Quenching • Like in medicine, hard probes can be used to investigate the medium properties • If created matter is opaque, a jet depositing its energy should eventually disappear jet suppression University Wuppertal, “Schul-Vorlesungen zur Physik” Trigger particle What can the energy lost tell us about the medium properties?

7. Jets in HIC I Can energy lost by jets tell us something about medium properties? IF the medium behaves like a fluid: Mach cones have to occur because of fluid dynamics Mach cone angle sensitive to EoS • By observation: • Confirm fast thermalization • Study EoS of the fluid

8. Jets in HIC II • Redistribution of energy to lower pT-particles • Re-appearance of the away-side for low and intermediate pTassoc H. Stöcker, Nucl. Phys. A 750, 121 (2005), J. Casalderrey-Solana et al. Nucl. Phys. A 774, 577 (2006) 4 < pTtrigger < 6 GeV/c 0.15 < pTassoc < 4 GeV/c Au+Au / p+p = 200 GeV STAR, Nucl. Phys. A 774, 129 (2006) PHENIX, Phys. Rev. C 77, 011901 (2008) Reflect interaction of jet with medium

9. Experimental Studies

10. Jet - Studies in HIC I Position of away-side peaks does not change strongly with pTassoc Not due to Cherenkov gluon radiation What happens to larger pTtrigger? STAR, Phys. Rev. C 82, 024912 (2010) see also PHENIX, Phys. Rev. C 77, 011901 (2008)

11. Jet - Studies in HIC II Investigation of path length dependence: Double-peaked structure becomes more pronounced out-of-plane Could be due to deflection A. Sickeles [PHENIX], Eur. Phys. J. C 61, 583 (2009)

12. Jet - Studies in HIC III Centrality dependence: double-peaked structure for central collisions one peak structure for very peripheral collisions PHENIX, Phys. Rev. Lett. 97, 052301 (2006) Energy Scan: double-peaked structure occurs at about the same angle for different collision energies Mach cone??? J. Jia, Eur. Phys. J. C 62, 255 (2009)

13. Some caveats

14. Background Subtraction D. d’Enterria and BB., Springer Lecture Notes (2008) • Assumption (Two-source model) : • No correlations between flow anisotropy • and jets • ZYAM (Zero Yield At Minimum) • Subtraction of: • estimated elliptic flow modulated • background • can leads to: • double peaked structure How can one proof/disproof the two-source model? Background: Particle correlation from elliptic flow J. Ulery [STAR], PoS LHC07, 036 (2007)

15. 3-Particle Correlations ptrigT=3 – 4 GeV, passocT=1 – 2 GeV • Three-particle correlations seem to corroborate Mach cone idea • What’s the effect of ZYAM? • No agreement with 3-particle cumulant method C. Pruneau, Phys. Rev. C 79, 044907 (2009) J. Ulery [STAR], Int. J. Mod. Phys. E 16, 2005 (2007) Deflected jet Mach Cone ptrigT>3 GeV, passocT=1 – 2 GeV C. Pruneau, Talk at the Workshop on ‘Critical Asessment of Theory and Experiment on Correlations at RHIC’, BNL, February 2009

16. Theoretical Approach

17. STAR, Phys. Rev. Lett. 95, 152301 (2005) • Conversion into particles Freeze-out: Modelling of Jets • Medium created in a HIC can be described using hydrodynamics Jets can be modelled using (ideal) hydrodynamics: residue of energy and momentum given by the jet . e+p v • Assumption of • isochronous/isothermal freeze-out • No interaction afterwards mainly flow driven

18. The Static Medium

19. Stopped Jet I Applying a static medium and an ideal Gas EoS for massless gluons Maximal fluid response Assume: Near-side jet is not modified by medium BB et al., Phys. Rev. C 79, 034902 (2009) Jet decelerating from v=0.999 according to Bethe-Bloch formalism Bragg Peak a=-1.36 GeV/fm adjusts path length Simplest back-reaction from the medium

20. Stopped Jet II t=4.5/v fm BB et al., Phys. Rev. C 79, 034902 (2009) Mach cone for sound waves Diffusion wake

21. Stopped Jet III BB et al., Phys. Rev. C 79, 034902 (2009) Normalized, background-subtracted isochronous Cooper-Frye at mid-rapidity pT = 5 GeV Energy Flow Distribution Assuming: Particles in subvolume will be emitted into the same direction Diffusion wake causes peak in jet direction Any conclusions about deposition mechanism???

22. Stopped Jet IV • Jet stops after t=4.5/v fm BB et al., Phys. Rev. C 79, 034902 (2009) tFO=4.5/v fm tFO=6.5/v fm tFO=8.5/v fm Diffusion wake still present Vorticity conservation

23. Stopped Jet V Larger impact of thermal smearing Diffusion wake causes peak in jet direction BB et al., Phys. Rev. C 79, 034902 (2009) tFO=4.5/v fm tFO=6.5/v fm tFO=8.5/v fm

24. A Comparison

25. Mach Cones in Transport BAMPS: Boltzmann Approach of MultiParton Scatterings A transport algorithm solving the Boltzmann equations for on-shell partons with pQCD interactions Box scenario, no expansion, massless Boltzmann gas interactions, 2 -> 2 C. Greiner, Talk at the Opening Symposium of the JET Collaboration, Berkeley, June 2010 • The shock front (Mach front) gets broader and vanish with more dissipation

26. Different Jet-Energy Loss Modells

27. P. Chesler and L. Yaffe, Phys. Rev. D 78, 045013 (2008) Modelling Jets using … Energy density perturbation Pointing vector perturbation Strongly-coupled theory AdS/CFT v=0.75 Energy density perturbation Momentum density perturbation Weakly-coupled theory pQCD R. Neufeld et al, Phys. Rev. C 78, 041901 (2008) v=0.99955 Conclusion about Mach cones?

28. Jets in AdS/CFT Non-Mach correlations caused by Neck region J. Noronha et al., Phys. Rev. Lett. 102, 102301 (2009)

29. Heavy Quark Jets

30. Heavy Quark Jets Compare weakly and strongly coupled models using heavy punch-through jet Static medium and isochronous freeze-out needed for comparison BB et al., Phys. Lett. B 675, 340 (2009) pQCD: Neufeld et al. source for a heavy quark R. Neufeld et al, Phys. Rev. C 78, 041901 (2008) AdS/CFT: Stress tables with S. Gubser et al, Phys. Rev. Lett. 100, 012301 (2008) t=4.5/v fm J. Noronha et al., Phys. Rev. Lett. 102, 102301 (2009) BB et al., Phys. Lett. B 675, 340 (2009) No Mach-like peaks: AdS/CFT: Strong influence of the Neck region pT = 3.14 GeV

31. The Expanding Medium

32. Expanding Medium I Experimental results based on many events b=0 Consider different jet paths A. K. Chaudhuri, Phys. Rev. C 75, 057902 (2007) , A. K. Chaudhuri, Phys. Rev. C 77, 027901 (2008) • Apply Glauber initial conditions and an ideal Gas EoS for massless gluons • Focus on radial flow contribution dE/dt = 1 GeV/fm Etot = 5 GeV • Two-particle correlation • (Tfreeze-out < Tcrit = 130 MeV): near-side jet Jet 150

33. Expanding Medium II BB et al., arXiv: 1005.5461 Etot = 5 GeV pTtrig= 3.5 GeV broad away-side peak double peaked structure due to non-central jets vjet =0.999 PHENIX, Phys. Rev. C 77, 011901 (2008)

34. Expanding Medium III Etot = 10 GeV pTtrig = 7.5 GeV broad away-side peak double peaked structure Strong impact of the Diffusion wake 6 < pTtrigger < 10 1.5 < pTassoc < 2.5 Causes smaller dip for pT=2 GeV Yield STAR, Phys. Rev. C 82, 024912 (2010) Path length dependence Centrality dependence f

35. Expanding Medium IV Comparing different deposition scenarios, one sees that „cone“ angle approximately the same for different deposition scenarios pTtrig= 3.5 GeV pTassoc= 2.0 GeV pTassoc= 3.0 GeV vjet =0.999 BB et al., arXiv: 1005.5461 pTassoc= 2.0 GeV: No double-peakedstructurefor pure energy depositionscenario due to thermal smearking

36. Expanding Medium V Considering a bottom quark (M=4.5 GeV), propagating at vjet < cs (on-shell energy-momentum deposition scenario) pTassoc= 2.0 GeV BB et al., arXiv: 1005.5461 PHENIX, PRL98, 232302 (2007) Conical emission angle also appears for subsonic jets Not a Mach cone Cu+Cu: Similaraway-sideshoulderwidth, double-peakstructurereapparsforpTassoc = 3 GeV

37. Some more caveats

38. Hot Spots I Can fluctuating initial condition explain the 2+3-particle correlations? Takahashi et al, PRL 103, 242301 (2009) R. Andrade et al., arXiv: 0912.0803 F. Grassi, Talk at the Glasma Workshop, BNL, May 2010

39. Hot Spots II Check with one single hot spot Au, De/e0=0.2 Heavy quark jets are not affected

40. Fluctuating Initial Conditions

41. Initial Fluctuations I Glauber initial conditions: P. Sorensen J. Phys. G 37, 094011 (2010), B. Alver et al., Phys. Rev. C 81, 054905 (2010) due to symmetry, odd Fourier components vanish Fluctuating initial conditions: B. Alver, Talk at the Glasma Workshop, BNL, May 2010 higher Fourier components may occur

42. Initial Fluctuations II • v3 is extensively studied B. Alver et al., Phys. Rev. C 81, 054905 (2010), B. Alver et al., arXiv: 1007.5469 H. Petersen et al., arXiv: 1008.0625 B. Alver et al., arXiv: 1007.5469 Calculating v3 using a viscous hydro model with initial conditions deformed according to the eccentricities from a Glauber and a KLM (CGC) model v3 not negligable small

43. Why v3 deformations cannot be the whole story • Correlation in Df1-Df2 • Df1/2 120° • No correlation in Dh1-Dh2 What are the consequences of triangular flow? B. Alver et al., Phys. Rev. C 81, 054905 (2010) Shock front?? 120° ptrigT=3 – 4 GeV, passocT=1 – 2 GeV J. Ulery [STAR], Int. J. Mod. Phys. E 16, 2005 (2007) ~ 120 What is the difference of v3 and the impact of hot spots? Do we only see fluctuating initial conditions? Study of heavy quark jets needed

44. Summary • „Conical“ signal can be created (general effect): by averaging over wakes created by jets in different events. There is a deflection of particles emitted due to collective transverse flow. Quite insensitive to deposition mechanism, jet velocity (even for subsonic jets), and system size Structure cannot directly be related to EoS, but is a measure for the flow • „Conical“ correlationscouldarisefrom multiple non-Mach sources Mach coneshavetooccur in heavy-ioncollisionsifthereis a fluid Necessary to study heavy-flavor tagged jets.