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Heavy Flavors at FAIR

Heavy Flavors at FAIR. E lena Bratkovskaya 28.06.2008 , WE-Heraeus-Seminar „ Characterization of the Quark Gluon Plasma with Heavy Quarks‘‘, Bad Honnef (Germany). Introduction. FAIR energies are well suited to study dense and hot nuclear matter – a phase transition to QGP ,

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Heavy Flavors at FAIR

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  1. Heavy Flavors at FAIR Elena Bratkovskaya 28.06.2008 , WE-Heraeus-Seminar „Characterization of the Quark Gluon Plasma with Heavy Quarks‘‘, Bad Honnef (Germany)

  2. Introduction • FAIR energies are well suited to study dense and hot nuclear matter – • a phase transition to QGP , • chiral symmetry restoration, • in-medium effects Observables for CBM: • Excitation function of particle yields and ratios • Transverse mass spectra • Collective flow • Dileptons • Open and hidden charm • Fluctuations and correlations • ... The way to study: • Experimental energy scan of different observables in order to find an ‚anomalous‘ behaviour in comparison with theory Microscopic transport models provide a unique dynamical description of nonequilibrium effects in heavy-ion collisions

  3. Basic concept of HSD • HSD – Hadron-String-Dynamics transport approach • for each particle species i (i = N, R, Y, p, r, K, …) the phase-space density fi followsthe transport equations • with collision termsIcoll describing: • elastic and inelastic hadronic reactions: baryon-baryon, meson-baryon, meson-meson • formation and decay of baryonic and mesonicresonances • string formation and decay (for inclusive particle production: BB -> X , mB ->X, X =many particles) • implementation of detailed balance on the level of 1<->2 • and 2<->2 reactions (+ 2<->n multi-particle reactions in HSD) • off-shell dynamics for short-lived states BB <-> B´B´, BB <-> B´B´m mB <-> m´B´, mB <-> B´ Baryons: B=(p, n, D(1232), N(1440), N(1535), ...) Mesons: m=(p, h, r, w, f, ...)

  4. AGS NA49 BRAHMS HSD – a microscopic model for heavy-ion reactions • very good description of particle production in pp, pA reactions • unique description of nuclear dynamicsfrom low (~100 MeV) to ultrarelativistic (~20 TeV) energies HSD 1999 predictions

  5. Heavy flavor sector reflects the early dynamics since heavy hadrons can onlybe formed in the very early phase of heavy-ion collisions at FAIR/SPS! Open and hidden charm • Hidden charm: J/Y , Y‘: Anomalous J/Y suppression in A+A (NA38/NA50/NA60) J/Y‚normal‘absorption by nucleons (Glauber model) || Experimental observation: extra suppression in A+A collisions; increasing with centrality

  6. Digal, Fortunato, Satz hep-ph/0310354 Quarkonium dissociation temperatures: I.-II. Scenarios for charmonium suppression in A+A • I. QGP threshold melting • [Satz et al’03] • II. 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 Dissociation energy density ed ~ 2(Td/Tc)4 cC melting J/Y

  7. Charm and Charmonium production and absorption in HSD • Charmonium = hard probe => binary scaling! • Productions(J/Y) ands(Y‘ )in N+N and p+N collsions:parametrization of the available exp. data Coupled channel problem: sJ/Yexp = sJ/Y + B(cc->J/Y)scc + B(Y‘->J/Y) sY‘ • Charmonia-baryon dissociation cross • sections can be fixed from p+A data: • scc B=sJ/Y B=sc B= 4.18 mb,sY‘ B= 7.6 mb • (adopting a Glauber fit from NA50) J/Y(cc,Y‘) + B --> D+Dbar +X

  8. II. Modelling of the comover scenario in HSD 1. Charmonia dissociation cross sections withformedp, 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*) aredetermined bydetailed balance! Note: comover dissociation as well as DDbar recombination can occure only if the local energy density at the collision point e < 1GeV/fm3 PRC 67 (2003) 054903

  9. (II.) Charmonium recombination by D-Dbar 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! PRC 67 (2003) 054903

  10. I. Modelling of the QGP melting scenario in HSD Energy density e(x=0,y=0,z;t) from HSD for Au+Au collisions at 21300 A GeV Energy density e(x=0,y=0,z;t) from HSD for Pb+Pb collisions at 160 A GeV 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; arXiv:0801.4282, NPA 807 (2008) 79

  11. (I.) ‚Local‘ energy density e versus Bjorken energy density eBj • transient time for central Au+Au at 200 GeV: • tr ~ 2RA/gcm ~ 0.13 fm/c • c-cbar formation time: • tC~ 1/MT ~ 1/4GeV ~ 0.05 fm/c < tr • c-cbar pairs are produced in the initial hard NN • collisions in time period tr Y‚ J/Y cc • Bjorken energy density: AT is the nuclei transverse overlap area t is the formation time of the medium • 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

  12. J/Y and Y´ suppression in In+In and Pb+Pb at SPS: (II.) Comover absorption (+ recombination by D-Dbar annihilation) • Exp. data (NA50/NA60) for J/Y and Y´ suppressionfor Pb+Pb and In+In at 160 A GeV are consistent with the comover absorption model for the same set of parameters! [Olena Linnyk et al., nucl-th/0612049, NPA 786 (2007) 183 ]

  13. J/Y and Y´ suppression in In+In and Pb+Pb at SPS: (I.)QGP threshold melting scenario Dissociation energy density:e(J/Y)=16 GeV/fm3, e(cc ) =2 GeV/fm3, e(Y‚) =2 GeV/fm3 • J/Ysuppression is qualitatively described,butQGP threshold melting scenario shows a too strong Y‚ absorption, which contradicts the NA50 data! [Olena Linnyk et al., nucl-th/0612049, NPA 786 (2007) 183 ]

  14. J/Y and Y´ suppression in Au+Au at RHIC: (II.) Comover absorption (+ recombination by D-Dbar annihilation) Olena Linnyk et al., nucl-th/0612049, NPA 786 (2007) 183; arXiv:0801.4282, NPA 807 (2008) 79 In the comover scenario the J/Y suppression at mid-rapidity is strongerthan at forward rapidity, unlike the data! Pure comover scenario is ruled out by PHENIX data!

  15. J/Y and Y´ suppression in Au+Au at RHIC: (I.)QGP threshold melting scenario [Olena Linnyk et al., arXiv:0705.4443, PRC 76 (2007) 041901 ] Satz’s model: complete dissociation of initial J/Y and Y´ due to the huge local energy densities ! Charmonia recombinationby D-Dbar annihilation is important, however, it can not generate enough charmonia, especially for peripheral collisions! QGP threshold melting scenario is ruled out by PHENIX data!

  16. Summary (I.-II. ) I. QGP ‚threshold melting‘ versus experimental data SPS RHIC J/Y survival:+- Y‚/ J/Y ratio :- ? • II. Comover absorption • (+ recombination by D-Dbar annihilation) • versus experimental data • SPS RHIC • J/Y survival:+ - • Y‚/ J/Y ratio :+? Comover absorption and threshold melting scenarios are ruled out by experimental data evidence for non-hadronic interaction ?!

  17. III. Scenarios for charmonium suppression in A+A • III. Pre-hadronic interaction scenario : • early interactions of charmonium (ccbar) and D-mesons with unformed (i.e. under formation time t = g tF , tF ~0.8 fm/c in the hadron rest frame) baryons and mesons - pre-hadrons • + comover absorption with recombination by D-Dbar annihilation • Dissociation cross sections of charmonium by pre-hadrons: • sdiscc pre-Baryon= 5.8 mb, • sdiscc pre-meson= 2/3sdiscc pre-Baryon • Elastic cross sections with prehadrons: Charmonium - prehadrons:D-meson - prehadrons: • selcc pre-Baryon= 1.9 mb,selD pre-Baryon= 3.9 mb, • selcc pre-meson= 2/3 selcc pre-BaryonselD pre-meson= 2/3selcc pre-Baryon • Pre-hadronic interaction scenario only ‚simulates‘ the interactions in the QGP in the Hadron-String model without (!) explicit partonic interactions and phase transition => NOT (yet!) a consistent description !=> PHSD Fitted to PHENIX data

  18. J/Y and Y´ suppression in Au+Au at RHIC: (III.) Pre-hadronic interaction scenario Olena Linnyk et al., arXiv:0801.4282, NPA 807 (2008) 79 In the prehadronic interaction scenario the J/Y rapiditydistribution has the right shape like the PHENIX data! => candescribe the RHIC data at s1/2=200 GeV for Au+Au at mid- and forward-rapidities simultaneously.

  19. J/Y and Y´ suppression in Au+Au at RHIC Olena Linnyk et al., arXiv:0801.4282, NPA 807 (2008) 79 PHENIX data:  evidence for non-hadronic interactions of charm degrees of freedom !

  20. J/Y excitation function FAIR FAIR • 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/Ymelting scenario with charmonia recombination by DDbar annihilation shows a maximum suppression at Ebeam = 1 A TeV; • exp. data ? [Olena Linnyk et al., arXiv:0801.4282, NPA 807 (2008) 79 ]

  21. Y´ excitation function FAIR FAIR Y´ suppression provides independent information on absorption versus recreation mechanisms ! [Olena Linnyk et al., arXiv:0801.4282, NPA 807 (2008) 79 ] [Olena Linnyk et al., arXiv:0705.4443, PRC 76 (2007) 041901 ]

  22. HSD predictions for J/Y and Y´ suppression in Au+Au at CBM energies Different scenarios can be distinguished already at FAIR energies: Y´ over J/Y ratio is lower in the comover absorption model since the average comover density decreases only moderately with lower bombarding energy whereas the energy density decreases rapidly [Olena Linnyk et al., arXiv:0705.4443, PRC 76 (2007) 041901 ]

  23. HSD: v2 of D+Dbar and J/Y from Au+Au versus pT and y at RHIC • Pre-hadronic interactions lead to an increase of the elliptic flow v2 • The pre-hadronic interaction scenario is ~consistent with the preliminary PHENIX data on the D-mesons v2 • => strong initial flow of non-hadronic nature! [Olena Linnyk et al., arXiv:0801.4282, NPA 807 (2008) 79 ]

  24. HSD predictions for CBM - elliptic flow at 25 A GeV • HSD:D-mesons and J/Y follow the charged particle flow =>small v2 Possible observation at CBM: strong initial flow of D-mesons and J/Y due to partonic interactions! Challenge for CBM!

  25. 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 atSPS, while Y´/J/Ydataappear to be in conflict with the ‚melting scenario‘. • Comover absorption and threshold meltingfail to describe the RHIC data at s1/2=200 GeV for Au+Au at mid- and forward-rapidities simultaneously • Prehadronic interaction scenario can describe the RHIC data at s1/2=200 GeV for Au+Au at mid- and forward-rapidities simultaneously • STAR data on v2 ofhigh pT charged hadrons and charm D mesons are not reproduced in the hadron-string picture => evidence for a plasma pressure ?!

  26. Outlook • FAIRis anexcellent facilitytostudy the properties of the sQGP (strongly interacting ‚color liquid‘) as well as hadronic matter • Transport theory is thegeneral basisfor an understanding of nuclear dynamics on a microscopic level UrQMD: U+U, 25 A GeV

  27. Thanksto Olena Linnyk Wolfgang Cassing Horst Stöcker

  28. - More slides -

  29. (II.) Comover absorption (+ recombination by D-Dbar annihilation) D+Dbar transverse pT spectra from Au+Au – HSD predictions • Interactions (inelastic and elastic) of D/Dbar and J/Y withhadronic medium change the shape of the initial spectra (i.e. at the production point). • However, a full thermalization of charm (charmonium) pT spectra is NOTachieved in the hadron-string model [E. B., W. Cassing, H. Stöcker, N. Xu, PRC 71 (2005) 044901]

  30. Supression in cold nuclear matter Charmonium is absorbed by scattering on baryons [OL et al., arXiv:0801.4282 ]

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