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RHIC – from Vacuum Engineering to Exotic Particle Factory

RHIC – from Vacuum Engineering to Exotic Particle Factory. Huan Zhong Huang ( 黄焕中 ) CUSPEA ’84 Department of Physics and Astronomy University of California Los Angeles Department of Engineering Physics Tsinghua University. Outline.

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RHIC – from Vacuum Engineering to Exotic Particle Factory

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  1. RHIC – from Vacuum Engineering to Exotic Particle Factory Huan Zhong Huang (黄焕中) CUSPEA ’84 Department of Physics and Astronomy University of California Los Angeles Department of Engineering Physics Tsinghua University

  2. Outline • Relativistic Heavy Ion Collider (RHIC) and Quark-Gluon Plasma (QGP) • Formation of Dense Partonic Matter • Hadronization of Bulk Partonic Matter • Exotic Particle Factory • Outlook

  3. STAR Relativistic Heavy Ion Collider --- RHIC Au+Au 200 GeV N-N CM energy Polarized p+p up to 500 GeV CM energy

  4. Quark-Hadron Phase Transition

  5. Vacuum Engineering-- The Melting of Quarks and Gluons Matter Compression: Vacuum Heating: Deconfinement High Temperature Vacuum -- high energy heavy ion collisions -- the Big Bang High Baryon Density -- low energy heavy ion collisions -- neutron starquark star

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

  7. High pT Phenomena at RHIC Very dense matter has been created in central Au+Au collisions! This dense matter is responsible for the disappearance of back-to-back correlation and the suppression of high pT particles ! -- Jet Quenching! Is the energy loss due to parton or hadron stage? Is there a noticeable difference in experimental phenomenon related to quarks versus gluons? Is there a difference between heavy quark and light quark energy loss in the dense medium?

  8. Expectations for High pT from Au+Au Use number of binary nucleon-nucleon collisions to gauge the colliding parton flux: N-Binary Scaling  RAA = 1 N-Binary Scaling works for very rare processes i.g., Drell-Yan and direct photon production with some caveats (parton F2 and G change in A). RAA can also be measured using central/peripheral ratios !

  9. The Suppression is the Same for p0 and h – parton level effect No suppression for direct photons – photons do not participate in strong interaction with medium!

  10. No Significant Difference BetweenQuarks and Gluons at High pT Baryons more likely from gluon fragmentations in the pQCD region

  11. STAR No Significant Difference Between Heavy Quark Meson and Light Quark Mesons Non-photonic electrons from heavy quark decays Charged hadrons

  12. High pT Phenomena at RHIC Very dense matter has been created in central Au+Au collisions! This dense matter is responsible for the disappearance of back-to-back correlation and the suppression of high pT particles ! The mechanism for parton energy loss is yet to be understood ! The dynamics of jet-medium interactions (Mach cone or not) requires more studies !

  13. coordinate-space-anisotropy  momentum-space-anisotropy y py px x Initial/final conditions, dof, EOS Elliptic Flow Parameter v2

  14. Elliptic Flow: ultra-cold Fermi-Gas • Li-atoms released from an optical trap exhibit elliptic flow analogous to what is observed in ultra-relativistic heavy-ion collisions • Elliptic flow is a general feature of strongly interacting systems!

  15. Elliptic Flow v2 PRL 92 (2004) 052302; PRL 91 (2003) 182301 Hydro calculations break-down at higher pT (as expected). How is v2 established at pT above 2 GeV/c? Why is baryon v2 larger than meson v2?

  16. Constituent Quark Degree of Freedom Hadronization Scheme for Bulk Partonic Matter: • KS – two quark coalescence • – three quark coalescence from the partonic matter surface?! Particle v2 may be related to quark matter anisotropy !! pT < 1 GeV/c may be affected by hydrodynamic flow ! Quark Coalescence – (ALCOR-J.Zimanyi et al, AMPT-Lin et al, Rafelski+Danos, Molnar+Voloshin …..) Quark Recombination – (R.J. Fries et al, R. Hwa et al)

  17. Constituent Quark Scaling Constituent (n) Quark Scaling -- Meson n=2 and Baryon n=3 grouping Some deviation due to internal hadron structure

  18. Strangeness from Bulk Partonic Matter RCP X L Constituent Quark Number Scaling -- Hadronization through quark clustering -- Effective DOF – constituent quarks quasi-hadrons at Tc ? Lattice QCD picture? W f

  19. Intermediate pT Dynamics At hadronization the manifested effective degrees of freedom seem to be in constituent quarks ! Multi-parton dynamics – clustering of quarks – could be responsible for -- increased baryon production -- strange baryon enhancement -- strong elliptic flow at intermediate pT !!! Hadronization of bulk partonic matter -- different phenomenon from e+e- collisions !

  20. Multi-Parton Dynamics for Bulk Matter Hadronization Essential difference: Traditional fragmentation  particle properties mostly determined by the leading quark ! Emerging picture from RHIC data (RAA/RCP and v2)  all constituent quarks are almost equally important in determining particle properties ! v2 of hadron comes from v2 of all constituent quarks ! The fact that in order to explain the v2 of hadrons individual constituent quarks (n=2-meson,3-baryon) must have a collective elliptic flow v2 and the hadron v2 is the sum of quark v2  Strong Evidence for Deconfiement !

  21. 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

  22. RHIC – Exotic Particle Factory STAR – Exciting Physics Program A full TOF upgrade will greatly enhance STAR’s capability !! Chinese STAR Group SINAP Tsinghua University USTC CCNU, Wuhan IMP, Lan Zhou IHEP Construction to be finished by 2008 Full installation in 2009 Full Barrel TOF Using MRPC

  23. RHIC Physics Outlook Heavy Ion Physics: 1) Properties of high density QCD matter 2) Chiral symmetry at high temperature and density 3) Search for exotic particles/phenomena at RHIC 4) Search for critical point (low energy scan) RHIC Spin Physics Using Polarized p+p Collisions: 1) the gluon spin structure function  major milestone to understand the spin of the proton! 2) sea quark spin structure function 3) quark transverse spin distribution

  24. End of Talk

  25. Heavy quark has less dE/dx due to suppression of small angle gluon radiation Y. Dokshitzer & D. Kharzeev PLB 519(2001)199 “Dead Cone” effect M. Djordjevic, et. al. PRL 94(2005)112301 J. Adams et. al, PRL 91(2003)072304 Heavy quark energy loss: Early Expectations Radiative energy loss of heavy quarks and light quarks --- Probe the medium property ! What went wrong?

  26. B and D contributions to electrons Experimental measurement of B and D contributions to non-photonic electrons ! Direct measurement of D and B mesons

  27. Au + Au Collisions at RHIC STAR Central Event (real-time Level 3)

  28. 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? )

  29. The Field & Feynman picture of cascade fragmentation Kretzer@ISMD04

  30. Baryon Production from pQCD e+e-jet fragmentation from SLD p p K K p p Normal Fragmentation Cannot Produce the Large Baryon Yield

  31. Too Many Baryons at Intermediate pT

  32. Casalderrey-Solana, Shuryak, Teaney, hep-ph/0411315 pTtrig=4-6 GeV/c, pTassoc=0.15-4 GeV/c F. Wang (STAR), QM’04 talk, nucl-ex/0404010. Now published: STAR, PRL 95, 152301 (2005). STAR preliminary data motivated sonic-boom prediction Actually sonic-boom was first predicted in the 70’s by the Frankfurt school. Many recent studies: H. Stoecker, nucl-th/0406018. Muller, Ruppert, nucl-th/0507043. Chaudhuri, Heinz, nucl-th/0503028. Y.G. Ma, et al. nucl-th/0601012.

  33. Experimental Statistical and Systematic Errors c-cbar production CS PHENIX 0.92+-0.15+-0.54 mb 0.567+-0.057+-0.224 mb STAR 1.4+-0.2+-0.4 mb Errors taken seriously High pT region does not contribute to total CS much. Difference between STAR and PHENIX has to be resolved !!

  34. pK+ and pK- from 18.4 M d+Au at 200 GeV Background – Combinatorial and Correlated Pairs Intriguing Situation Regarding Pentaquark States D++ M (GeV/c2) M (GeV/c2) Statistical significance ~ 4s Intriguing ! Not conclusive yet ! Another long d+Au run will resolve this uncertainty !

  35. Radiative Energy Loss not Enough Moore & Teaney, PRC 71, 064904 (2005) Large collisional (not radiative) interactions also produce large suppression and v2

  36. Charm Quark in Dynamical Model (AMPT) Large scattering cross sections needed !

  37. Spin Physics Program The Spin Structure of the Proton: ½ = ½ SDq + DG + <L> q  up, down and strange quarks G  gluons L  angular momentum of quarks and gluons Experimentally: 1) total spin in quarks ~ 30% 2) sea quarks are polarized too 3) little info about the gluon polarization 4) even less know about <L> and how to measure <L>

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