Jet Correlations from PHENIX: From Low-pT to High-pT 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 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. Correlations and Fluctuations N.Grau 07/07/06

Correlations and Fluctuations Jet Quenching nucl-ex/0510023 Moderate pT jets are suppressed Pedestal&flow subtracted STAR PRL 91, 072304 (2003) Lower pT jets are suppressed and broadened nucl-ex/0507004 accepted Single particle suppression pattern persists to 20 GeV Correlations and Fluctuations N.Grau 07/07/06

Constructing Jet Correlations Df Mixed events – corrects pair acceptance Hard scattering Resonance decays Df (rad) Elliptic flow Total C(Df) Sum over all events  jets measured on a statistical basis Correlations and Fluctuations N.Grau 07/07/06

High-pT Jet Correlations Correlations and Fluctuations N.Grau 07/07/06

Correlations and Fluctuations 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 N.Grau 07/07/06

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 N.Grau 07/07/06

Away-Side Yield Suppression PHENIX 8 < pT(trig) < 15 GeV/c h-h correlations in Au+Au Near-side unmodified Away-side yield is suppressed! nucl-ex/0604018 J. Jia Hard Probes 2006 Correlations and Fluctuations N.Grau 07/07/06

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 Red – gluons from energy loss. Black – scattering of parent partons Correlations and Fluctuations N.Grau 07/07/06

Lack of Away-Side Broadening! D. Magestro QM2005 8 < pT(trig) < 15 GeV/c Trigger 5-10 GeV/c Widths do not change between p+p and Au+Au?!? Correlations and Fluctuations N.Grau 07/07/06

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 N.Grau 07/07/06

Punch-through Events (II) Comparison of MC to STAR away-side yields. Yield suppression sensitive to the probability of punch-through Correlations and Fluctuations N.Grau 07/07/06

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 N.Grau 07/07/06

Correlations and Fluctuations 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 N.Grau 07/07/06

Different Colliding Systems and Energies Cu+Cu @ 200 GeV Au+Au @ 62.4 GeV Au+Au @ 200 GeV Correlations and Fluctuations N.Grau 07/07/06

Parameterize the Away-Side Shape trigg assoc D D assoc 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 N.Grau 07/07/06

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 N.Grau 07/07/06

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 N.Grau 07/07/06

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 N.Grau 07/07/06

Mach Cones in From Theory Mach shocks do not produce the two-particle correlation structure? Hydro calculation of energy lost by jets Remnant jet Backsplash U. Heinz HP2006 Correlations and Fluctuations N.Grau 07/07/06

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 N.Grau 07/07/06

For the future: 3-Particle Correlations (II) High pT (2.5<pT<4) p1 p2-a p3-a Correlation Variables : Study the 3-particle correlations in the “high-pT reference frame” Project associated particles to perpendicular plane (1<pT<2.5) Correlations and Fluctuations N.Grau 07/07/06

For the future: 3-Particle Correlations (III) θ* = 120 θ* = 60 θ* = 180 v2 subtracted Correlation Function θ* = 120 θ* = 60 θ* = 180 PHENIX Preliminary 20-40 % Correlations and Fluctuations N.Grau 07/07/06

For the future: Direct g-h PRL 94 232301 (2005) g Hadrons 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 N.Grau 07/07/06

Inclusive g-h Correlations in Au+Au C(Df) Df Df C(Df) 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 N.Grau 07/07/06

Summary of pT Evolution h± --- h± p0 --- h± C: 0-20% 1 2 3 4 5 6 7 8 PT Partner PT Trigger 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 N.Grau 07/07/06

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 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 N.Grau 07/07/06

Correlations and Fluctuations Backup Correlations and Fluctuations N.Grau 07/07/06

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 N.Grau 07/07/06

Correlations and Fluctuations g-h Near Side Yields PRL 94 232301 (2005) ~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 N.Grau 07/07/06

For the future: RP-Dependence At Higher pT Qualitatively: No hint of a volcano shape in any RP bin Correlations and Fluctuations N.Grau 07/07/06