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D – D Correlations as a Sensitive Probe of Light – quark Thermalization

D – D Correlations as a Sensitive Probe of Light – quark Thermalization. Kai Schweda, University of Heidelberg. A. Dainese, X. Dong, J. Faivre, Y. Lu, H.G. Ritter, L. Ruan, A. Shabetai, P. Sorensen, N. Xu, H. Zhang, Y. Zhang. Outline. Introduction

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D – D Correlations as a Sensitive Probe of Light – quark Thermalization

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  1. D – D Correlations asa Sensitive Probe of Light – quark Thermalization Kai Schweda, University of Heidelberg A. Dainese, X. Dong, J. Faivre, Y. Lu, H.G. Ritter, L. Ruan, A. Shabetai, P. Sorensen, N. Xu, H. Zhang, Y. Zhang.

  2. Outline • Introduction • Strange - quark flow: partonic collectivity • Heavy - quark collectivity • Summary

  3. Quark Gluon Plasma Source: Michael Turner, National Geographic (1996) • Quark Gluon Plasma: • Deconfined and • thermalized state of quarks and gluons •  Study partonic EOS at RHIC and LHC(?) Probe thermalization using heavy-quarks

  4. Heavy Ion Collisions Heavy-Flavor X, W, f D++, L* p, K, p Time  Temperature Tch = 160-170 MeV Tfo = 100 MeV 1) Initial condition: 2) System evolves: 3) Bulk freeze-out: - baryon transfer - parton/hadron expansion - hadronic dof - ET production - interaction cease - Partonic dof Tth, <bT> Plot: Steffen A. Bass, Duke University

  5. Kinetic Freeze-out 1) Compared to p, K, and p, multi-strange particles ,  are found at lower <T>but higher T ~ Tch Collectivity prior to hadronization 2) Sudden single freeze-out*:Resonance decays lower Tfo for (p, K, p) Collectivity prior to hadronization  take snapshot at early (partonic?) stage Data: STAR, Nucl. Phys. A715, 129c(2003). *A. Baran, W. Broniowski and W. Florkowski; nucl-th/0305075

  6. Anisotropy Parameter v2 coordinate-space-anisotropy  momentum-space-anisotropy y py px x Initial/final conditions, EoS, degrees of freedom

  7. v2 in the Low-pT Region P. Huovinen, private communications, 2004 • Minimum bias data! At low pT, model result fits mass hierarchy well! • - Details do not work, need more flow in the model !

  8. v2 of Multi-strange Hadrons f,X,andW do flow = Strangeness flows partonic collectivity at RHIC ! * Inconsistencies in current hydro calculations STAR Preliminary, QM05 conference

  9. Collectivity, Deconfinement at RHIC - v2, spectra of light hadrons and multi-strange hadrons - scaling with the number of constituent quarks At RHIC, it seems we have:  Partonic Collectivity • Deconfinement  Thermalization ? • PHENIX: PRL91, 182301(03) • STAR: PRL92, 052302(04) • S. Voloshin, NPA715, 379(03) • Models: Greco et al, PRC68, 034904(03) • X. Dong, et al., Phys. Lett. B597, 328(04). • ….

  10. Quark Masses • Symmetry is broken: EW Higss mass QCD dynamical mass • In QGP, c- and b-quark stay heavy • c- and b-quark good probe for medium created at RHIC/LHC • If heavy quarks flow:  frequent interactions among all quarks light quarks (u,d,s) likely to be thermalized X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu, et al., hep-ph/0604178, subm. to PRL.

  11. The key point is to determine Heavy-Flavor Collectivity D0, D, D+s, L+C, J/y, …

  12. V. Greco et al. PLB 595(2004)202 B. Zhang et al. nucl-th/0502056 Non-photonic electron v2 c (b)  e + X • Large syst. uncertainties due to large background • charm collective flow at pt < 2GeV/c • v2(e) favors non-zero v2(c) at pT(e)<2 GeV/c.

  13. J/yEnhancement at RHIC(LHC) • Statistical hadronization  strong centrality dependence of J\y yield at LHC • Need total charm yields ! • Measure D0, D±, Lc • Probe deconfinement and thermalization  scc Calculations: P. Braun Munzinger, K. Redlich, and J. Stachel, nucl-th/0304013.

  14. [1] A. Andronic et al., Phys.Lett. B571 (2003) 36-44 [2] PHENIX, Phys.Rev.Lett. 96 (2006) 032001 [3] STAR, Phys. Rev. Lett. 94 (2005) 062301 J/y yield vs Centrality Statistical Hadronization Synopsis: - Complete screening of primordial J/ψ’s - J/ψ’s regenerated at chemical freezout from thermalized c-cbars Disagrees with STAR Barely touches PHENIX data Large uncertainties in total c-cbar yield  need precise reference for total charm ! STAR Preliminary

  15. Multiply Heavy-flavored Hadrons • Statistical hadronization- de-confined heavy-quarks • equilibrated heavy-quarks •  Enhancement up to x1000 ! • Measure Xcc, Wcc, Bc, (Wccc) • Need total charm yields • Probe deconfinement and thermalization @ LHC • QGP ! Quarks and gluons  hadrons Pb+Pb Wccc / D : p+p x1000 F. Becattini, Phys. Rev. Lett. 95, 022301 (2005); P. Braun Munzinger, K. Redlich, and J. Stachel, nucl-th/0304013.

  16. Df D - Meson Pair Correlations c cbar • ccbar pair production: DDbar pairs are correlated ! • Here: Df correlation • If charm equilibrates  correlations vanish ! • Influence of hadronic scattering (small) ? Pythia Calcs.: H. Woehri, priv. comm. Hadronic Transport Model:E.L. Bratkovskaya et al., PRC 71 (2005) 044901.

  17. Pythia Predictions • p +p : Pyhtia predicts DDbar – correlations • Stronger at larger pT • Back-to-back corr. • Modified in QGP ? X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu, et al., hep-ph/0604178, subm. to PRL.

  18. c - cbar in QGP RHIC LHC • Langevin approach- describe c-quarks in QGP- a: momentum-space diffusion- fragment c  hadrons • At small pT corr. smear out • At large pT corr. preserved • Heavy-quark resonances in QGP  a: increases !  Correlations vanish up to pT = 3 GeV ! X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu, et al., hep-ph/0604178, subm. to PRL.

  19. Hadronic Re-scattering • Hadronic re-scattering can not completely wash out DD-correlations • Frequent partonic re-scattering needed  light quark thermalization ! X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu, et al., hep-ph/0604178, subm. to PRL.

  20. Summary • Strange – quarks flow f, X, and W  Deconfinement at RHIC • Heavy – quarks (c, b) are precise probes • Measure D - Dbar correlations Probe (u,d,s)-quark thermalization • Deconfinement + Thermalization = QGP !

  21. STAR @ RHIC / ALICE @ LHC Heavy Flavor Tracker • e.g.: D0 K + p, ct = 123mm • Measure precisely secondary decay vertex • Use silicon pixel technology •  precise heavy-flavor measurements at RHIC and LHC !

  22. Use high pT as probe Probe the bulk response Partons lose energy in medium Response of medium to pressure Measure nuclear modification factor RAA Measure elliptic flow v2 Partonic energy loss dE/dx, gluon density Partonic equation of state EoS Two Different Ways to Probe Bulk • It’s all about interactions • Interactions  collectivity (e.g. flow) • Frequent interactions  Thermalization

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