Jet Correlations from PHENIX: From Low-p T to High-p T

1. Jet Correlations from PHENIX: From Low-pT to High-pT • Many thanks to Paul Constantin, Wolf Holzmann, Jiangyong Jia, Jiamin Jin, and Hua Pei for work I’m showing. • Also thanks to Brian Cole, Barbara Jacak, Craig Ogilvie, Paul Stankus, and Mike Tannenbaum for useful discussions. Nathan Grau, Columbia University, Nevis Labs For the PHENIX Collaboration • Focus entirely on A+A collisions • High-trigger pT correlations • Can we do jet tomography? • What does theory tell us? • Low-trigger pT correlations • Away-side shape modification • RP dependence Correlations and Fluctuations

2. nucl-ex/0507004 accepted nucl-ex/0510023 STAR PRL 91, 072304 (2003) Pedestal&flow subtracted • Moderate pT jets are suppressed • Lower pT jets are suppressed and broadened Jet Quenching • Single particle suppression pattern persists to 20 GeV Correlations and Fluctuations

3. Df Total Elliptic flow C(Df) Hard scattering Resonance decays Df (rad) Constructing Jet Correlations Mixed events – corrects pair acceptance Sum over all events  jets measured on a statistical basis Correlations and Fluctuations

4. High-pT Jet Correlations Correlations and Fluctuations

5. Away-Side Jet in Au+Au! • C(Df) strength ~ S/B of jets • Red and blue lines are the uncertainty in v2 • Jets seen above the background for trigger >5 GeV/c and associated >2 GeV/c Correlations and Fluctuations

6. Clear Away-Side in Cu+Cu! • Larger jet S/B in central Cu+Cu than central Au+Au • v2 modulation is smaller as well Correlations and Fluctuations

7. h-h correlations in Au+Au Near-side unmodified Away-side yield is suppressed! PHENIX 8 < pT(trig) < 15 GeV/c Away-Side Yield Suppression nucl-ex/0604018 J. Jia Hard Probes 2006 Correlations and Fluctuations

8. Black – scattering of parent partons Red – gluons from energy loss. Expected Broadening of Away-Side I. Vitev hep-ph/0501255 • Consequence of energy loss is broadening of the away-side correlations • multiple scattering of the parton • gluon radiation Correlations and Fluctuations

9. 8 < pT(trig) < 15 GeV/c Lack of Away-Side Broadening! D. Magestro QM2005 Trigger 5-10 GeV/c Widths do not change between p+p and Au+Au?!? Correlations and Fluctuations

10. Punch-through Events (I) T. Renk hep-ph/0602045 • Monte Carlo includes radial expansion reducing the effect of DE ~ L2 • Non-zero probability to lose no energy • Away-side only sensitive to none-zero energy loss? Production vertices of events with trigger > 8 GeV Red circles indicate an associated hadron (> 4 GeV) suffering no E-loss Correlations and Fluctuations

11. Punch-through Events (II) • Yield suppression sensitive to the probability of punch-through Comparison of MC to STAR away-side yields. Correlations and Fluctuations

12. Non-zero Probability for E-loss • Important quantitative question not answered by theorists: • ASW • qhat = 15 GeV/fm2 and L=2 • P(0) ~30-40%! • GLV • P(0) ~ 0%! • Can these data help constrain this result? Weidemann, Vitev Hard Probes 2006 Correlations and Fluctuations

13. Lower pT Correlations • h-h Correlations in Au+Au (upper plots) • C(Df) strength ~ jet S/B • Few % S/B at lowest pT Correlations. • h-h Correlations with background subtracted (lower plots) Correlations and Fluctuations

14. Cu+Cu @ 200 GeV Au+Au @ 62.4 GeV Different Colliding Systems and Energies Au+Au @ 200 GeV Correlations and Fluctuations

15. assoc D trigg D assoc Parameterize the Away-Side Shape Could be a “bent” jet or a mach/ Cherenkov cone Parameterize the away-side shape as a double Gaussian that are offset symmetrically around Df = p by fit parameter D. Correlations and Fluctuations

16. Physical Mechanism of the Away-Side Structure • Deflection due to flowing medium • Sensitive to jet + bulk interaction • hep-ph/0411341, Armesto, Salgado, Wiedemann • Shoulder position dependent on the RP orientation. • Cones • Mach cones • measure speed of sound • nucl-th/0406018 Stoecker, hep-ph/0503158 Muller, Ruppert, hep-ph/0411315 (2004) Casalderrey-Solana, Shuryak, Teaney • Cerenkov Cones • measure index of refraction • nucl-th/0507063 Koch, Majumder, Wang • Both would conclude shoulder position independent of RP orientation. • Distinguish by pT dependence to the shape. • Do we understand the root-s and system size evolution? Correlations and Fluctuations

17. Au+Au Reaction Plane Dependence (I) Look at 4th bin since it has the smallest v2. Dip exists at most central before substraction! Correlations and Fluctuations

18. Au+Au Reaction Plane Dependence (II) Know v2 depending on triggers RP orientation. J. Bielcikova et al, Phys. Rev. C69:021901, 2004 Correlations and Fluctuations

19. Remnant jet Backsplash Mach Cones in From Theory • Mach shocks do not produce the two-particle correlation structure? • Hydro calculation of energy lost by jets U. Heinz HP2006 Correlations and Fluctuations

20. H H H For the future: 3-Particle Correlations (I) • 3-particle correlations = 3 jet + 2 jetx1 thermal + 1 jetx2 thermal + 3 thermal. • Determining background is difficult • 3 jet correlation signal-to-background worse than 2 jet correlation signal-to-background • Looking for few % effect. Correlations and Fluctuations

21. High pT (2.5<pT<4) p1 p2-a p3-a Correlation Variables : For the future: 3-Particle Correlations (II) • Study the 3-particle correlations in the “high-pT reference frame” • Project associated particles to perpendicular plane (1<pT<2.5) Correlations and Fluctuations

22. θ* = 180 θ* = 180 θ* = 120 θ* = 120 θ* = 60 θ* = 60 v2 subtracted Correlation Function For the future: 3-Particle Correlations (III) PHENIX Preliminary 20-40 % Correlations and Fluctuations

23. g Hadrons For the future: Direct g-h PRL 94 232301 (2005) • Direct photons not suppressed in the medium. • Much less “trigger bias” i.e. less biased toward skin emission • Photon measures jet energy  measured away-side D(z) modification Correlations and Fluctuations

24. C(Df) C(Df) Df Df Inclusive g-h Correlations in Au+Au g: 5-10 GeV/c h: 1-2 GeV/c g: 5-10 GeV/c h: 3-5 GeV/c Comparison with p0 triggered data necessary to extract direct photon correlations. NB: a dip at p exists in the left CF after subtraction Correlations and Fluctuations

25. PT Partner 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 PT Trigger h± --- h± p0 --- h± C: 0-20% Summary of pT Evolution • The jet functions in Au+Au collisions evolve with both partner and trigger pT Away-side peak visible Away-side shoulders visible Neither visible Based on PHENIX preliminary and nucl-ex/0507004 P. Stankus CIPANP06 Correlations and Fluctuations

26. Summary and Conclusions • High-pT triggered correlations show • Au+Au away-side not broadened • A suppressed away-side yield consistent with punch-through jets. • What is learned about the medium from this data? • Low-pT triggered correlations show a strongly modified away-side shape • independent of system size and collision energy • Independent of trigger orientation to the RP • What is learned about the medium from this data? • Still left to do with current data • Three particle correlations: Sorting out deflected, vs. mach/cerenkov • Further RP studies: Can we show DE ~ L2,L,Ln? • Direct g-h: D(z) modification Correlations and Fluctuations

27. Backup Correlations and Fluctuations

28. Comparison of g- and p0- Triggered Widths Near-side widths are consistent between g-triggered and p0-triggered. Dominant inclusive photon correlation is decay from jet fragments Correlations and Fluctuations

29. PRL 94 232301 (2005) g-h Near Side Yields ~50% direct photons above 5 GeV/c in the most central. Also seen in g-triggered near side yield ratio to p0 -triggered yield. Correlations and Fluctuations

30. For the future: RP-Dependence At Higher pT • Qualitatively: No hint of a volcano shape in any RP bin Correlations and Fluctuations