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Recent STAR Results on NPE and Hyperon-Hyperon Correlations

Recent STAR Results on NPE and Hyperon-Hyperon Correlations. Huan Zhong Huang 黄焕中 Department of Physics and Astronomy University of California Los Angeles, CA 90095-1547 July 23-25, 2012, STAR Regional Meeting @ SDU. Outline. Parton Energy Loss and Jet-Medium Interaction

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Recent STAR Results on NPE and Hyperon-Hyperon Correlations

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  1. Recent STAR Results on NPE and Hyperon-Hyperon Correlations Huan Zhong Huang 黄焕中 Department of Physics and Astronomy University of California Los Angeles, CA 90095-1547 July 23-25, 2012, STAR Regional Meeting @ SDU

  2. Outline • Parton Energy Loss and Jet-Medium Interaction • Heavy Ion Collisions as Exotic Factory Facility • Outlook

  3. partonic hadronic A QCD Partonic Matter in Heavy Ion Collisions QCD – fundamental corner stone of the Standard Model - Condense Matter Physics with underlying QCD interaction Three Intriguing Aspects: -- QCD Topological Objects/CME/LPV -- Properties of QCD Partonic Matter -- QCD Phases and Phase Boundary Heavy Quarks @RHIC: Mostly produced at t=0, and an excellent probe for properties of QCD matter !

  4. pT Scales and Physical Processes RCP Three PT Regions: -- Fragmentation -- multi-parton dynamics (recombination or coalescence or …) -- Hydrodynamics (constituent quarks ? parton dynamics from gluons to constituent quarks? ) Need NPE to access high pT region !

  5. Jet – Medium Interactions Jet and/or medium induced particle emission Leading particle jet energy loss (trigger) Near-Side Jet-h or NPE-h correlations RAA and v2 Away-Side Trig-hadron angular correlations Df = ftrig-fhadron

  6. NPE spectra and RAA Most central 5% AuAu collisions NPE RAA Scaled NPE in p+p NPE spectrum in AuAu from Wenqin Xu’s thesis RAA~ 0.3 at pT= 4-6 GeV/c, NPE indeed suppressed !

  7. Model comparison Model calculation, impact parameter =0, i.e. 0% central This analysis, 0-5% central M. He, R. J. Fries, R. Rapp, arXiv:1106.6006 Model: heavy quarks collide with light quarks and form hadrons A non-perturbative process, with effective potential from LQCD About 4 times larger collision cross-section than pQCD considerations, and agrees with data

  8. Bottom versus Charm in the Model M. He, R. J. Fries, R. Rapp, arXiv:1106.6006 Both data and theory have large uncertainty c/b very different • 1: hadron formation (non-pQCD) in medium (?), parameter tuning • 2: Bottom (B-mesons) loss much less energy than Charm quarks (D-mesons) • bottom/charm ratio is not precisely known, • Large uncertainty on model RAA

  9. Heavy Quark Elliptic flow RAA alone is not sufficient ! More constraints – e.g., differential suppression w.r.t. azimuthal angle -- caused by HQ thermalization (low pT) and/or different path lengths (high pT) Shorter path length Less energy loss Path length dependence of energy loss generates v2 Longer path length More energy loss y The path-length-dependence sensitive to different mechanisms: ϕ, azithmual Collision Energy Loss: smaller v2 or x Radiative Energy Loss: ADS/CFT Energy Loss: larger v2

  10. Results and model comparison This analysis Same Model for RAA • Model NPE v2 < Measured NPE v2 • smaller but Close • different centrality in model: • b =7.0 fm ~ 40%centrality • Measured NPE v2 • charm/bottom combined • very statistically limited at higher pT • 0-60% centrality • Sizeable NPE elliptic flow: yes • Heavy Quark elliptic flow : not necessarily • To identify path-length-dependence • need more statistics to reach high pT D0 10

  11. Conic Emission or V3 Initial Geometry More particles are emitted in a cone direction on the away-side !! Dynamics: Mach cone effect from supersonic jets passing thru the medium? Gluon radiation? parton scattering? Geometry: v3 initial state Use Heavy Quarks!! pTtrig= 2.5-4.0 GeV/c; pTasso= 1.0-2.5 GeV/c Au+Au Mark Horner (for STAR Collaboration): J. Phys. G: Nucl. Part. Phys. 34 (2007) S995

  12. NPE-h Correlation Raw NPE-h Subtract the modulated v2 background assume NPE v2=5% assume NPE v2=10% Broadening in the away-side Energy Loss or else ? 12

  13. Remarks on Parton E Loss Parton Energy Loss  Hadron PT Scale > 5-6 GeV/c Intrinsically a Dynamical Evolution System (path length?) ! -- Rapid Decrease of Energy Density with Evolution Time -- Even partons originated from the center of the hot/dense fireball may escape Theoretically Eloss calculations – dynamic issue simultaneous calculation of RAA and v2 at high pT !! Medium Response to Jets Plowing Through -- Heavy quark interactions with medium - non-photonic electron – hadron correlations - D – h correlations , NPE-NPE correlations -- Separate Charm and Bottom energy loss – Heavy Flavor Tracker Upgrade– 2014 !

  14. Potential exotic particles/phenomena: penta-quark states (uudds, uudds!) di-baryons H – (L-L, uuddss) [W-W] (ssssss) strange quark matter meta-stable Parity/CP odd vacuum bubbles disoriented chiral condensate …… Discoveries from Unexpected Areas?! RHIC -- Frontier for bulk partonic matter formation (quark clustering and rapid hadronization) -- Factory for exotic particles/phenomena STAR’s capability has been enhanced greatly with recent upgrades !! 14

  15. Physics Information in Correlation Function L-L Correlation Function: both Ls from the primary vertex – if there is a LL resonance state -- enhanced peak at resonance and attractive L-L interactions if there is a bound state H, then two Ls near threshold can form H -- depletion of L-L correlations (WRT a reference?!) (if we can measure p-n correlation, the effect of deuteron formation) both Ls from secondary vertices – weak decay product – [X-L] state? 15

  16. Correlation Function and Direct Decay Searches Complementary Correlation Function – Depletion of phase space due to bound state formation -- inclusive, sensitive to total yield Direct Searches -- depend on branching ratio If H(uuddss) is a weakly bound state with a binding energy ~ 10s MeV as predicted by recent Lattice QCD calculations, HL+p+p branching ratio? 16

  17. Search for di-hyperons and study hyperon-hyperon interactions from correlation measurement • The scattering length (a0) and the effective range (reff) with no, weak, medium, and strongcoupling to -N : a0 (fm) reff (fm) No coupling -2.42 -6.36 weak (Set.A) -2.47 -6.65 medium (Set.B) -2.98 -13.53 strong (Set.C) -2.27 -2.61 • Current fit parameters is consistent with non-existence of a strongly bound state of  • 0-40% Au+Au @ 200 GeV STAR Preliminary Set A – Weak N coupling Set B – Medium N coupling Set C – Strong N coupling Fit A. Ohnishi and T. Furumoto

  18. Search the Lpp Channel • ~ 23 M events • candidates – mass within 4 MeV of PDG value • pp pair – mass below L PDG mass by 5 MeV 0-10 % Au+Au @ 200 GeV

  19. Search the Lpp Channel The rotational method reproduces the background better Nature is not kind enough to give us ‘H’ particle We will continue to search for other candidates 0-10 % Au+Au @ 200 GeV LL

  20. RHIC – a dedicated QCD Facility Having a great run! Even greater potential for future discoveries ! (Deconfinement Phase Transition) AA Exotic AA pA pp pp pA (CGC,EMC) (spin)

  21. End

  22. Volcanic mediate pT – Spatter (clumps) An Equilibrated Partonic System L X W Use coalescence picture to study partons at the phase boundary 22

  23. Effective Parton Distribution in the QM Drop at Hadronization L Parton Spectroscopy at RHIC X W f Use particle emission to measure partonpT distribution and angular anisotropy (v2) in the dense parton drop !! More theoretical development – He, Fries and Rapp, Phys.Rev. C82 (2010) 034907

  24. Features of Partonic Matter Central Au+Au Collisions at RHIC Bulk Partonic Matter -- 1) parton collectivity, multi- parton dynamics coalescence/recombination 2) v2 and pT distributions for effective quarks -- evolution from gluons – constituent quarks 3) Intriguing dynamics of baryon rich matter at low energy L X W 4) Major shift in DOF between 11-39 GeV?!

  25. W/f ratios @ 11.5 GeV also deviates from 39-200 GeV What is the collision energy where the deviation from partonic dominated matter becomes eminent? -- 2011 data from 19.6 and 27.0 GeVAu+Au collisions -- Perhaps more scan between 11.5 and 19.6 needed

  26. V2 and RAA are Related Precise value of v2 at pT> 6, 10 GeV/c ? RAA at pT > 10 GeV/c at RHIC should RAA approach unity at higher pT ? Future measurements will shed more lights on possible physical scenarios for parton energy loss dynamics ! Heavy Quarks will be special -- Lorentz g dependence on partonELoss on jet-medium interaction near-side vs away-side?

  27. Volcanic high pT -- Strombolian eruption Volcanic mediate pT – Spatter (clumps) Volcanic low pT – Bulk matter flows Nucleus-Nucleus Collisions and Volcanic Eruption 27

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