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Olena Linnyk

Charmonium in heavy ion collisions. Olena Linnyk. 16 July 2007. Anomalous J/ Y suppression. Charm sector reflects the dynamics in the early phase of heavy-ion collisions !. J/ Y ‚normal‘ absorption by nucleons (Glauber model) Experimental observation (NA38/50/60):

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Olena Linnyk

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  1. Charmonium in heavy ion collisions Olena Linnyk 16 July 2007

  2. Anomalous J/Y suppression Charm sector reflects the dynamics in the early phase of heavy-ion collisions ! J/Y ‚normal‘ absorption by nucleons (Glauber model) Experimental observation (NA38/50/60): extra suppression in A+A collisions; increasing with centrality

  3. cC melting J/Y Scenarios for anomalous charmonium suppression • Comover absorption • [Gavin & Vogt, Capella et al.`97] absorption by low energy inelastic scattering with ‚comoving‘ mesons (m=p,h,r,...) • QGP colour screening • [Digal, Fortunato, Satz ’03] Quarkonium dissociation T: J/Y+m <-> D+Dbar Y´ +m <-> D+Dbar cC +m <-> D+Dbar Dissociation energy density ed ~ 2(Td/Tc)4

  4. D J/Y Y‘ cC Dbar Check the scenarios using transport models 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 HSD– Hadron-String-Dynamics transport approach

  5. Charmonium production in pN Hard probe ->binary scaling! sJ/Yexp = sJ/Y + B(cc->J/Y) scc + B(Y´->J/Y) sY´

  6. Modelling the comover scenario in HSD 1. Charmonia dissociation cross sections withp, r, KandK*mesonsJ/Y(cc,Y‘) + meson (p, r, K , K*) <-> D+Dbar • Phase-space model for charmonium + meson dissociation: constant matrix element 2.J/Yrecombination cross sections by D+Dbar annihilation: D+Dbar -> J/Y (cc,Y‘) + meson(p, r, K , K*) are determined by detailed balance! [PRC 67 (2003) 054903]

  7. Modeling the QGP melting in HSD Energy density e(x=0,y=0,z;t) fromHSD Threshold energy densities: J/Ymelting: e(J/Y)=16 GeV/fm3 cc melting: e(cc ) =2 GeV/fm3 Y‚melting: e(Y‚) =2 GeV/fm3 [Olena Linnyk et al., nucl-th/0612049, NPA 786 (2007) 183 ]

  8. Charmonium recombination by DDbar annihilation At SPS recreation of J/Y by D-Dbar annihilation is negligible NDD~16 But at RHIC recreation of J/Y by D-Dbar annihilation is strong!

  9. Comparison to data

  10. Pb+Pb and In+In @ 158 A GeVcomover absorption Pb+Pb and In+In @ 160 A GeV consistent with the comover absorption for the same parameter set! [OL et al NPA786 (2007) 183]

  11. Pb+Pb and In+In @ 158 A GeV QGP threshold melting Y´ absorption too strong, which contradict data [OL et al NPA786 (2007) 183] e(J/Y)=16 GeV/fm3, e(cc ) =e(Y‚) =2 GeV/fm3

  12. Au+Au @ s1/2=200 GeVComover absorption Energy density cut ecut=1 GeV/fm3 reduces the meson comover absorption || Space for partonic effects In the comover scenario the J/Y suppression at mid-rapidity is stronger than at forward rapidity, unlike the data! [OL et al arXiv:0705.4443]

  13. Energy density cut ecut=1 GeV/fm3 reduces the meson comover absorption, however, D+Dbar annihilation can not generate enough charmonia, especially for peripheral collisions! Satz’s model: complete dissociation of initial J/Y and Y´ due to the very large local energy densities ! Au+Au @ s1/2=200 GeVThreshold melting Charmonia recombination is important! QGP threshold melting scenario is ruled out by PHENIX data!

  14. J/Y excitation function 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 recreationshows a maximum suppression at Ebeam = 1 A TeV;exp. data ?

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

  16. 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 are in conflict with the melting scenario. • Comover absorption and colour screening fail to describe Au+Au at s1/2=200 GeV at mid- and forward rapidities simultaneously. • 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). PHSD - transport description of the partonic and hadronic phases

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

  18. Back-up slide 1local energy densityvsBjorken energy density • transient time for central Au+Au at 200 GeV: tr ~ 2RA/gcm ~ 0.13 fm/c • cc formation time: tC ~ 1/MT ~ 1/4GeV ~ 0.05 fm/c < tr • cc pairs are produced in the initial NN collisions in time period tr Y‚ J/Y cc AT is the nuclei transverse overlap area t is the formation time of the medium Bjorken energy density: at RHICeBjt ~ 5 GeV/fm2/c ‚Local‘ energy density e during transient time tr: e ~ 5[GeV/fm2/c] / [0.13 fm/c] ~ 30 GeV/fm3 accounting tC :e~ 28 GeV/fm3 • HSD reproduces PHENIX data for Bjorken energy density very well • HSD results are consistent with simple estimates for the energy density

  19. Back-up slide 2 PHSD Initial A+A collisions – HSD: string formation and decay to pre-hadrons Fragmentation of pre-hadrons into quarks: using the quark spectral functions from the Dynamical QuasiParticle Model (DQPM) approximation to QCD DQPM: Peshier, Cassing, PRL 94 (2005) 172301; Cassing, arXiv:0704.1410[nucl-th], NPA‘07 • Partonic phase: quarks and gluons (= ‚dynamical quasiparticles‘) withoff-shell spectral functions (width, mass) defined by DQPM • elastic and inelastic parton-parton interactions:using the effective cross sections from the DQPM • q + qbar (flavor neutral) <=> gluon(colored) • gluon+ gluon<=> gluon(possible due to large spectral width) • q + qbar (color neutral) <=> hadron resonances Hadronization: based on DQPM - massive, off-shell quarks and gluons with broad spectralfunctions hadronize tooff-shell mesons and baryons: gluons  q + qbar; q + qbar  meson;q + q +q  baryon Hadronic phase: hadron-string interactions – off-shell HSD

  20. 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´

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