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Olena Linnyk

Charmonium dynamics in heavy ion collisions. Olena Linnyk. 28 June 2007. D. J/ Y. Y ‘. c C. D bar. Charmonium production vs absorption. Hadronization. Initial State. time. Freeze-out. Quark-Gluon-Plasma ?. Transport models.

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Olena Linnyk

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  1. Charmonium dynamics in heavy ion collisions Olena Linnyk 28 June 2007

  2. D J/Y Y‘ cC Dbar Charmonium production vs absorption Hadronization Initial State time Freeze-out Quark-Gluon-Plasma ? Transport models Microscopical transport models provide the dynamical description of nonequilibrium effects in heavy-ion collisions

  3. Basic concepts of Hadron-String Dynamics • for each particle species i (i = N, R, Y, p, r, K, …) the phase-space density fifollows the transport equations • with the collision terms Icoll describing: • elastic and inelastic hadronic reactions • formation and decay of baryonic and mesonic resonances • string formation and decay(for inclusive production: BB->X, mB->X, X =many particles) • Implementationof detailed balance on the level of 1<->2 and 2<->2 reactions (+ 2<->n multi-meson fusion reactions) • Off-shell dynamics for short living states BB <-> B´B´, BB <-> B´B´m, mB <-> m´B´, mB <-> B´

  4. Degrees of freedom in HSD • hadrons - baryons and mesons including excited states (resonances) • strings – excited colour singlet states (qq - q) or (q – qbar) • Based on theLUND string model • & perturbative QCDvia PYTHIA • leading quarks (q, qbar) & diquarks • (q-q, qbar-qbar) • NOT included in the transport modelspresented here: • no explicitparton-parton interactions(i.e. between quarks and gluons) outside strings! • noQCD EoSfor partonic phase under construction: PHSD – Parton-Hadron-String-DynamicsW. Cassing arXiv:0704.1410

  5. Charmonium production • Hard probe ->binary scaling!

  6. Charmonium production in pN sJ/Yexp = sJ/Y + B(cc->J/Y)scc + B(Y‘->J/Y) sY‘

  7. Regeneration At SPS recreation of J/Y by D-Dbar annihilation is negligible But at RHIC recreation of J/Y by D-Dbar annihilation is strong!

  8. Charmonium absorption Charmonium is absorbed by : • Scattering on nucleons (normal nuclear absorption, as in pA) • Interaction with secondary hadrons (comovers) • Dissociation in the deconfined medium (suppression in QGP)

  9. = NA50 (QM2002): Anomalous absorption of J/Y in very central Pb+Pb Discovery of QGP !? Normal absorption

  10. Digal, Fortunato, Satz hep-ph/0310354 cC melting J/Y Scenarios for anomalous charmonium suppression • QGP colour screening • [Matsui and Satz ’86] • Comover absorption • [Gavin & Vogt, Capella et al.`97]: • charmonium absorption by low energy inelastic scattering with ‚comoving‘ mesons (m=p,h,r,...) • J/Y+m -> D+Dbar • Y´ +m -> D+Dbar • cC +m -> D+Dbar but (!) • Lattice QCD predicts (2004): J/Y can exist up to ~2 TC ! • Regeneration of J/Y in QGP at TC[Braun-Munzinger, Thews, Ko et al. `01]J/Y+g <-> c+cbar+g but (!) • Comover density and meson absorption cross sections unknown • Regeneration (D+Dbar->J/Y+m)

  11. Digal, Fortunato, Satz hep-ph/0310354 Threshold melting = geometrical Glauber model[Blaizot et al.] • Charmonia suppression sets in abruptly at threshold energy densities, where • cc is melting, • Y´ is melting, • J/Y is melting • Lattice QCD: Comover absorption Phase-space model for cc+meson dissociation cC melting J/Y e(cc) =2 GeV/fm3 e(Y´) =2 GeV/fm3 e(J/Y)=16 GeV/fm3 Inverse cross sections by detailed balance! Scenarios for anomalous charmonium suppression in HSD • QGP colour screening • [Matsui and Satz ’86] • Comover absorption • [Gavin & Vogt, Capella et al.`97]: • charmonium absorption by low energy inelastic scattering with ‚comoving‘ mesons (m=p,h,r,...) • J/Y+m -> D+Dbar • Y´ +m -> D+Dbar • cC +m -> D+Dbar but (!) • Lattice QCD predicts (2004): J/Y can exist up to ~2 TC ! • Regeneration of J/Y in QGP at TC[Braun-Munzinger, Thews, Ko et al. `01]J/Y+g <-> c+cbar+g but (!) • Comover density and meson absorption cross sections unknown • Regeneration (D+Dbar->J/Y+m)

  12. Comparison to data

  13. Pb+Pb and In+In @ 158 A GeVJ/Y In+In consistent both with threshold melting and comover absorptionscenarios; Pb+Pb indicates importance of comover interaction [E.L.Bratkovskaya et al PRC69 (2004) 054903, OL et al NPA786 (2007) 183]

  14. Pb+Pb and In+In @ 158 A GeVY´ Y´ data contradict threshold melting scenario with lQCD ed

  15. Au+Au @ s1/2=200 GeVComover absorption In comover scenario, suppression atmid-y stronger than atforward y,unlike data Space for parton phase effects [OL et al arXiv:0705.4443]

  16. Au+Au @ s1/2=200 GeVThreshold melting Neither of the two scenarios describes PHENIX data

  17. J/Y excitation function e e Comover reactions in the hadronic phase give almost a constant suppression; pre-hadronic reactions lead to a larger recreation of charmonia with Ebeam . The J/Y melting scenario with hadronic comover recreation shows a maximum suppression at Ebeam = 1 A TeV;exp. data ?

  18. preliminary Y´ excitation function e e Y´ suppression provides independent information on absorption vs. recreation mechanisms !

  19. Summary • J/Y probes early stages of fireball and HSD is the tool to model it. • Comover absorption and threshold melting both reproduce J/Y survival in Pb+Pb as well as in In+In @ 158 A GeV, while Y´ data favour comover absorption. • Neither hadronic interactions nor colour screening satisfactory describes the data @ s1/2=200 GeV for Au+Au. • Deconfined phase is clearly reached at RHIC, but a theory having the relevant/proper degrees of freedom in this regime is needed to study its properties (PHSD).

  20. E. Bratkovskaya, W. Cassing, H. Stöcker Thank you! nucl-th/0612049 arXiv:0704.1410 arXiv:0705.4443

  21. Back-up slide 1 FAIR predictions

  22. Back-up slide 2 Energy density

  23. Back-up slide 3 Rapidity

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