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Unveiling Jet Topology via Multi-Particle Correlations

Unveiling Jet Topology via Multi-Particle Correlations. N. N. Ajitanand Nuclear Chemistry, SUNY, Stony Brook. A Cue from Lattice QCD:. Phase Transition. Brief historical perspective :. For phase transition to occur necessary to create energy density > 0.6 – 1.0 GeV/fm 3.

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Unveiling Jet Topology via Multi-Particle Correlations

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  1. Unveiling Jet Topology via Multi-Particle Correlations N. N. Ajitanand Nuclear Chemistry, SUNY, Stony Brook

  2. A Cue from Lattice QCD: Phase Transition Brief historical perspective : For phase transition to occur necessary to create energy density > 0.6 – 1.0 GeV/fm3

  3. PRL87, 052301 (2001) Extrapolation From ET Distributions peripheral collisions Central collisions time to thermalize the system (t0 ~ 0.2 - 1 fm/c) eBjorken~ 5 - 15 GeV/fm3 ~ 35 – 100 ε0 200 GeV Au+Au Collisions studies at RHIC! Achieved Energy Density is Well Above the Predicted Value for the Phase Transition N. N. Ajitanand Jyvaskyla 2007

  4. Strong quenching observed for high pt hadrons High Energy Density matter produced in 200 GeV Au + Au Initial anisotropy gives large pressure gradients hydro-like flow observed Quark scaling of v2 indicates flow sets in at the partonic stage N. N. Ajitanand Jyvaskyla 2007

  5. Phi meson Flow Even the phi which has a very low hadronic scattering cross-section develops a v2 which scales with the mesons. Strong indication of flow developing at the partonic stage N. N. Ajitanand Jyvaskyla 2007

  6. Lambda & Cascade Flow lambdas and cascades also show strong v2 according to the expected scaling pattern further supporting the view that flow sets in at the partonic stage N. N. Ajitanand Jyvaskyla 2007

  7. D Meson Flow Observation of significant flow for the D meson which implies charm flow N. N. Ajitanand Jyvaskyla 2007

  8. Charm Diffusion G. D. Moore, D. Teaney hep-ph/0412346 Calculation of the charm spectrum and the elliptic flow as a function of the diffusion coefficient implies surprisingly strong rescattering behaviour for the heavy quark. An indication of the rather special attributes of the matter formed. Strongly coupled liquid ? N. N. Ajitanand Jyvaskyla 2007

  9. Imaging Studies Source functions extracted forcharged pions produced in Au+Au collisions show non-Gaussian tails. Although a part of this effect may be trivially related to the contribution of resonances, the possibility of medium modification contributions is an interesting area of investigation. One way to do this would be to look at the source function at different orientations with respect to a high pt particle PHENIX Data to be published in PRL N. N. Ajitanand Jyvaskyla 2007

  10. Shear viscosity to Entropy ratio Theshear viscosity to entropy ratio (eta /s) is estimated for thehot and dense QCD matter created in 200 GeV Au+Au collisions atRHIC . A very low value~0.1 is found which is close to the conjectured lowerbound (1/4 pi ) R. Lacey et al. Phys. Rev. Lett. 98,092301 (2007) Such a low value is consistent with the observation of substantial elliptic flow and may provide the conditions for a special medium response to hard probes such as Mach flow N. N. Ajitanand Jyvaskyla 2007

  11. There is strong evidence to support the view that the medium thermalizes rapidly during the partonic stage and exhibits a high degree of collectivity. Study of the medium response to high pT probes is a natural next step N. N. Ajitanand Jyvaskyla 2007

  12. Jets are a natural probe of the Medium Finally partons fragment, (possibly) outside the medium Following hard collisions, scattered partons propagate through the medium radiating gluons and interacting with partons of the medium In relatvistic heavy ion collisions hard parton-parton processes occur early

  13. pT Jet Study via AssortedCorrelations High pT Hadron N(pT) Associated low pT particle Correlation Function

  14. Two source model gives : Correlation Flow Jet Condition Zero Yield At Minimum Sets a0 It is necessary to decompose the correlation function to obtain the Jet Function! Evaluate a0 Correlation Jet H(v2) Obtain using BBC Reaction Plane Large η gap nucl-ex/0501025 Ajitanand et. al. N. N. Ajitanand Jyvaskyla 2007

  15. Simulation Test of Jet Recovery Normal Jet Shape abnormal Jet Shape Line : Input Jet Correlation Squares : Extracted Jet Correlation Di-jet faithfully recovered N. N. Ajitanand Jyvaskyla 2007

  16. 200 GeV Au+Au : Hadron Jet Shapes PRL 97, 052301 (2006) 200 GeV Au+Au 1<pT<2.5 vs 2.5<pT<4.0 Jet-pair distributions resulting from decomposition show significant modification

  17. Meson vs. Baryon associated partner (for fixed Hadrontrigger) PHENIX Preliminary Associated mesons and baryons are similarly modified as would be expected If in-medium modification is the cause of the away side bending

  18. Possible Modifications of Jet Topology Mach Cone,Wake Effect or “sonic boom” Stoecker nucl-th/0406018 Muller,Ruppert Hep-ph/0503158 Casalderrey-Solana, Shuryak, Teaney, arXiv hep ph/0411315 (2004) Cherenkov Cone A. Majumdar Hard Probes 2006 Armesto,Salgado,Wiedemann hep-ph/0411341 Flow induced Deflection

  19. ADS-CFT duality Graviton perturbations of AdS_5-Schwarzschild generated by a string trailing behind an external quark moving with constant velocity are studied. Mach cone signals are generated in the medium Components of the stress tensor exhibit directional structures in Fourier space at both large and small momentum. The Mach cone angle seen is similar to that in the experiment J. Friess, S. Gubser, G. Michalogiorgakis, S. Pufu hep-th/0607022

  20. Analysing two-particle Jet correlations from Mach cone perspective Identify “Mach Cone ” region with shoulder and normal jet region with dip Shoulder Shoulder Dip N. N. Ajitanand Jyvaskyla 2007

  21. Dip to Shoulder ratio vs pT for different trigger pT ranges Behaviour for Au+Au is quite different from p+p indicating medium modification N. N. Ajitanand Jyvaskyla 2007

  22. The away side Icp Ratio of per-trigger yield: Icp Shoulder does not quench rapidly medium dominance Dip quenches rapidly jet dominance N. N. Ajitanand Jyvaskyla 2007

  23. * * * * f q f Df 12 12 13 Same Side Away Side Assoc. pTs (2,3) _ = * q = 3 Particle Correlations in High pT Framework (*) Hi pT(1) Polar plot along azimuth along radius Normal Jet

  24. Deflected and Cone Jet Sims High pT(1) High pT(1) 2-particle Correlations matched Mach Cone sim Deflected jet sim 3-Particle di-jet correlations allow a distinction between different mechanistic scenarios !

  25. PHENIX SIM Test of Harmonic removal Jet+Harmonic Jet Correlation = Total Correlation – a0*(Harmonic Correlation) “ao” is adjusted till Jet Correlation surface goes to zero at its minimum (ZYAM ) Ajitanand et.al. Phys. Rev. C 72, 011902 (2005) Input Jet Harmonic removed ZYAM gives good Jet Recovery

  26. Blue : Input Red : Recovered Flat Correlation Surface (offset added) Test of (2+1) removal (2+1) correlations obtained taking 2P in event 1 and 1P from event 2 For data relative amounts of soft-soft and hard-soft correlations set by relative strengths of observed 2P correlations True 3P Correlations absent True 3P Correlations present (2+1) processes successfully removed True 3P correlations successfully recovered

  27. Pairs per trigger from Correlation Pairs/trigger can be calculated from correlation function knowing detected singles and detected triplets Pairs per trigger Input N. N. Ajitanand Jyvaskyla 2007

  28. 3-particle Correlations without harmonic removal Data PHENIX Preliminary 60-90 % 40-60 % 20-40 % 5-10 % 0-5 % 10-20 % Most central shows jet dominated landscape with strong away side modification

  29. Jet Correlations Total 3-particle Jet Correlation Radial section True 3-particle Jet Correlation Strong away side modification in both total and true 3P Jet Correlations N. N. Ajitanand Jyvaskyla 2007

  30. Simulated Mach Cone Azimuthal Sections Data Total 3P jet correlations Simulated Deflected jet True 3P jet correlations The data validates the presence of a Mach Cone away-side jet but does not rule out contributions from other topologies.

  31. Et Et Phi Phi Eta Eta Simulated LHC Event PYTHIA Jets (PYTHIA + HIJING) Jetfinder algorithms N. N. Ajitanand Jyvaskyla 2007

  32. A novel method of jet location in an event has been developed which utilizes successive filtering of soft background using other events Step 1 Start PYTHIA Jet Soft background Step 8 Step 20

  33. Once hard jet candidates have been identified in a large number of events, the three-particle correlation method can be applied to look for medium modification Expected triplet jet correlation function for Mach flow signal in LHC events N. N. Ajitanand Jyvaskyla 2007

  34. Conclusions The high pt frame is a suitable choice for the study of jet topology via 3-particle correlations 3-particle jet correlations obtained for 200 GeV Au+Au 3-particle correlation without harmonic removal for most central case shows abnormal jet topology 3-particle Jet correlations show strong away side modification True 3-particle jet correlations validate presence of Mach Cone jets but do not rule out contributions from other topologies. Method a potential tool for jet study at the LHC N. N. Ajitanand Jyvaskyla 2007

  35. Tsunami : Nature’s awesome medium response to a hard event !! N. N. Ajitanand Jyvaskyla 2007

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