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Light and Heavy Hadronic Modes in Medium

Light and Heavy Hadronic Modes in Medium. Ralf Rapp Cyclotron Institute + Physics Department Texas A&M University College Station, USA Universit ät Bielefeld , 11.01.05. 1. Motivation: Relativistic Heavy-Ion Collisions. e + e -. J/ y. r. Au + Au. g. QGP ?!.

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Light and Heavy Hadronic Modes in Medium

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  1. Light and Heavy Hadronic Modes in Medium Ralf Rapp Cyclotron Institute + Physics Department Texas A&M University College Station, USA Universität Bielefeld, 11.01.05

  2. 1. Motivation:Relativistic Heavy-Ion Collisions e+ e- J/y r Au + Au g QGP ?! Hadron Gas “Freeze-Out” • Signatures of the QGP? • Suppression of J/y-Mesons • Decays of r-Mesons • Photons … Au + Au → X

  3. 1.2 Current Status:Towards QGP Discovery • So far: RHIC observables • ↔bulk properties of the produced matter: • - energy densitye≈20GeVfm-3↔ jet quenching(high-pt) • - thermalization + EoS↔ hydrodynamics (v0,v2) • - partonic degrees of freedom↔ coalescence (p/p,v2-scal) • Future: need to understand • microscopic properties (phasetransition, “QGP” !?): • - Deconfinement ↔quarkonia (J/y,, …) • - Chiral Symmetry Restoration↔ dileptons • ( - temperature ↔ photons )

  4. Outline 1. Introduction 2. Vacuum: Chiral Symmetry (Breaking) 3. (Light) Hadrons below Tc 3.1 Mesons: 0± (p-s), 1± (r-a1) , Baryons: N, D(1232) 3.2 Towards Chiral + Resonance Scheme 3.3 URHICs: Dileptons + Photons 4. Heavy-Quark Modes 4.1 Charmed Hadrons below Tc 4.2 Heavy-Quark Equilibration 4.3 Quarkonia in the QGP 4.4 URHICs: Suppression vs. Regeneration 5. Conclusions

  5. qR qL • Profound Consequences: • energy gap: • ↔ mass generation! • massless Goldstone bosonsp0,± • “chiral partners” split,DM≈0.5GeV: > > > > - - qR qL JP=0±1± 1/2± 2.) Chiral Symmetry in QCD:Vacuum SU(2)L× SU(2)R invariant (mu,d≈0) - Spontaneous Breaking:strongqqattraction  Bose Condensate fillsQCD vacuum! [cf. Superconductor: ‹ee›≠0 Magnet ‹M›≠0 , … ]

  6. a=1±(qq) (qqq) Chiral breaking: Q2 < (1.5-2 GeV)2 , J± < 5/2 (?!) 2.1 Light Hadrons: Vacuum Correlation Function: Timelike (q2>0) : ImPa(q0,q) → physical excitations

  7. lattice QCD - cm ‹qq› 1.0 T/Tc cPTmany-bodydegrees of freedom?QGP (2 ↔ 2)(3-body,...) (resonances?) consistentextrapolatepQCD 0 0.05 0.3 0.75 e[GeVfm-3] 120, 0.5r0 150-160, 2r0 175, 5r0 T[MeV], rhad 2.2 “Melting” the Chiral Condensate • Excite vacuum (hot+dense matter) • quarks “percolate” / liberated •  Deconfinement • ‹qq›condensate “melts”, ciral Symm. • chiral partners degenerate Restoration • (p-s, r-a1, … medium effects → precursor!) - How?

  8. 3. Hadrons in Medium: Light Sector (u,d) 3.1.1 0± Mesons: p and “s” 3.1.2 1± : r(770) and a1(1260) 3.2 Chiral + Resonance Scheme 3.3 Baryons: D(1232), N 3.4 Comparison to Lattice 3.5 URHICs: E.M. Probes (and Resonances)

  9. Ds→ Dp at Tc Precursor in nuclei ?! pA→(pp)S-WaveA > Sp = + > URHICs:- fluct. Ps(0,q→0) - ppM-spectra - (very) soft photons 3.1.1 Pion and Sigma in Medium Dp=[k02-wk2-Sp(k0,k)]-1 N,Dp N-1,D-1 • rNprevalent, smeared atT>0

  10. 3.1.2 (Axial-) Vector Mesons in Medium r Sp > Sp > (b) Effective Field Theory HLS with rL≡p (“VM”); vacuum: loop exp.O(p/Lc , mr/Lc , g) In-Med.: T-dep. of bare mr(0), gr via matching to OPE, Lmatch<Lc + RG-running to on-shell  dropping r-mass [Harada, Yamawaki, Sasaki etal] [Chanfray etal, Herrmann etal, RR etal, Koch etal, Weise etal, Post etal, Eletsky etal, Oset etal, …] (a) Hadronic Many-Body Theory Dr(M,q:mB,T)=[M2-mr2-Srpp-SrB-SrM ]-1 Propagator: Constraints: -B,M→rN,rp -gN,gA,pN→rN - QCDSRs, lattice B*,a1,K1... N,p,K…

  11. rB/r0 0 0.1 0.7 2.6 Model Comparison [Eletsky etal ’01] [RR+Wambach ’99] (i) r -Mesons at SPS Hot+Dense Matter Hot Meson Gas [RR+Gale ’99] [RR+Wambach ’99] • r-meson “melts” in hot and dense matter • baryon density rB more important than temperature

  12. e+e- Emission Rates: dRee/dM ~ f B ImPem - - [qq→ee] [qq+O(as)] baryon effects important even at rB,net=0: sensitive to rB,tot=rB+rB , f more robust ↔ OZI in-med HG ≈ in-med QGP ! - Quark-Hadron Duality ?! (ii) Vector Mesons at RHIC

  13. > D,N(1900)… Sp a1 Sp + + . . . > Sr N(1520) … > > Exp: - HADES(pA): a1→(p+p-)p - URHICs (A-A) : a1→pg 0  = (iii) Current Status of a1(1260)

  14. pS pS pS pS pS pP pP 3.2 Towards a Chiral + Resonance Scheme Options for resonance implementation: (i) generate dynamically from pion cloud [Kolomeitsev etal ‘03, …] (ii) genuine resonances on quark level → representations of chiral group [DeTar+Kunihiro ‘89, Jido etal ’00, …] e.g. p s N+ N(1535)- r a1D+ N(1520)- N(1900)+ D(1700)-(?) D(1920)+ rS (a1)S rS Importance of baryon spectroscopy to identify relevant decay modes!

  15. NN-1DN-1 Sp D + + + + ... > > > > > pD→N(1440), N(1520), D(1600) > in-medium vertex corrections incl. g’ p-cloud, (“induced interaction”) (1+ f p - f N) thermal p-gas > > 3.3 In-Medium Baryons: D(1232) and N(939)  long history in nuclear physics ! (pA , gA ) e.g. nuclear photoabsorption:MD , GDup by20-40MeV  little attention at finite temperature  D-Propagator at finite rB and T[van Hees+RR ’04]

  16. D(1232) Spectral Fct. at RHIC Nucleon Spectral Fct. at RHIC D in Nuclear g Absorption  broadening: Bose factor, pD→B  repulsion: pDN-1, pNN-1  substantial broadening due to resonant pN → B scattering D in Nuclei and Heavy-Ion Collisions

  17. 1- MEM 0- extracted [Laermann, Karsch ’04] 3.4 Lattice Studies of Medium Effects calculated on lattice

  18. calculate integrate More direct! Proof of principle, not yet meaningful (need unquenched) Comparison of Hadronic Models to LGT

  19. [Turbide,Gale+RR ’03] • consistent with dileptons • pp Brems with soft s at low q? baryon density effects! 3.5 Observables in URHICs e+ e- γ (i) Dileptons(ii) Photons Im Πem(M,q) Im Πem(q0=q)

  20. 4. Heavy-Quark Modes 4.1 Charmed Mesons below Tc 4.2 Heavy-Quark Equilibration 4.3 Charmonium in QGP 4.4 URHICs: Suppression vs. Regeneration

  21. [Grandchamp+RR ’03] 4.1 Charmed Mesons in Hadronic Matter mD(T,rB) expected to decrease (Chiral Symmetry Restoration) [Weise etal ’01]  reduced threshold for p,r + Y → DD  J/y robust  Y’ fragile: Y’→ DD decays

  22. 1-D Fokker Planck Eq. scatt. rate diff. const. e.g.: pQCD Xsections, T=500MeV, as=0.6(0.3)  g=0.25 (0.06) fm-1 ↔ 4-15fm/c(very) slow! Resonance cross section c + q → “D” → c + q ?! 4.2 Heavy-Quark Thermalization in QGP ? • Naively: 1 scatt. Q2≈ T2, (pt,therm)2≈ mcT Nscatt≈(pt,therm/Q)2 ≈5 • more quantitative: Boltzmann Eq. [Svetitsky ’88]

  23. chirally symmetric for light quarks • heavy-quark symmetry •  jm conserved to LO(1/mc) • parameters: mD(0), GD • [van Hees+RR ’04] 4.2.1 Resonant Open-Charm Rescattering _ _ “Light”-Quark Resonances c + q → “D” → c + q • effective model with pseudo/scalar • + axial/vector “D-mesons” 1.4Tc [Asakawa+ Hatsuda ’03]

  24. 4.2.2 Heavy-Quark Thermalization Times in QGP [van Hees+RR ’04] Charm Quarks Bottom vs. Charm pQCD “D” • resonance scatt. isotropic • secondary open-charm ?! • [50% for ] • bottom quarks “barely” • thermalize at RHIC

  25. 4.2.3 Single-e± Spectra at RHIC: D → e+nX Ellitpic Flow + Coalescence D jet- quench [Djordjevic etal ’04] B PHENIX 130AGeV e± does charm equilibrate? _ [Müller etal ’95, Molnar’04] • dynamical origin of resonances? cc production? • onset of pQCD regime:pt>5-6GeV ? open bottom? pt-Spectra: p-p vs Hydro [Batsouli etal. ’02] practically indistinguishable

  26. gluo-dissociation Dissociation Times Cross Sections [Bhanot+Peskin ‘84] “quasifree” diss. [Grandchamp+RR ‘01] [Datta etal ’03] 4.2 Charmonium in QGP • Lattice: hc, J/y survive up to ~2Tc • mass my ≈ const ~ 2mc* • width:

  27. - → ← J/y + g c + c + X for thermalized c-quarks: “jumps” at Tc sensitive to rather direct link to lattice QCD! Equilibration close to Tc ?! 4.3.1 Charmonium Regeneration vs. Suppression [PBM etal ’01, Gorenstein etal ’02, …] • statistical coalescence at Tc: chem.+therm. equil. • charmonia above Tc •  formation in QGP: detailed balance! [Thews etal ’01, Ko etal ’02 … Grandchamp+RR ’02]

  28. J/yExcitation Function • QGP regeneration dominant • sensitive to: • mc* , open-charm degeneracy, • (Ncc)2 ↔ rapidity, √s, A 4.3.2 Charmonium in A-A SPSRHIC [Grandchamp +RR ’03]

  29. 4.3.3 Upsilon in A-A [Lumpkins, Grandchamp, van Hees, Sun +RR ’05] LHC RHIC • bottomonium suppression as unique QGP signature ?! • caveat:  equil. number (very) sensitive to (mb)*, ttherm

  30. 5. Conclusions • Hadronic Many-Body Theory can provide: • - valuable insights into hadron properties in medium • - understanding of observables in nuclear reactions • The physics is often in the width (exception: e.g. “s”) • Interpretations? - many spectral properties appear to vary smoothly - connections to phase transition to be established - need nonperturbative symmetry-conserving approach, e.g. selfconsistent F-derivable thermodyn. potential

  31. Additional Slides

  32. pp Broadening+“s”+BE not enough?! (iii) Resonance Spectroscopy I: p+p- Spectra Sudden BreakupEmission Rate [Broniowski+Florkowski ’03] • r-mass shift ~ -50MeV • small “s” contribution • underestimates r/p [Shuryak+ Brown ’03]

  33. pN smean-field: (iv) Resonance Spectroscopy II : p+p Spectra D(1232) at RHIC D(1232) Spectral Fct. at RHIC [courtesy P. Fachini] Qualitatively in line with data (DMD=6 MeV ,DGD=65 MeV) DMD=+22MeV DGD =+(45±15)MeV

  34. (ii) D(1232) in URHICs  broadening: Bose factor, pD→B  repulsion: pDN-1, pNN-1 not yet included: (pN↔D)

  35. Direct Photons at SPS and RHIC [Turbide etal] • pQCD Cronin ~π0 • T0≈205MeV sufficient • new WA98 points: • pp-Bremsstr. via soft s ? • large “pre-equilibrium” yield • from parton cascade (no LPM) • thermal yields ~ consistent • QGP undersaturation small effect

  36. J/y Width from Lattice QCD

  37. E.M. Emission Rates [RR+Wambach ’99] However: peak in susceptibilities at Tc ↔ ms→ 0 Observables ? e+e-+pg, fluct, pp, J/y,... [Turbide,Gale+RR ’03] 3.1 Continuity?! Light Hadron “Masses” [Shuryak, Zahed, Brown ’04]

  38. generalizes coalescence [Greco,Ko+RR, in progress] 3.3 Light Hadrons in QGP • “Resonance” matter at 1-2Tc?! - EoS can be ok [Shuryak+Zahed’04] • assess formation rates from inelastic reactions • (as in charmonium case): q+q ↔ “p”+X , etc. • solve (coupled) rate equations • accounts for energy conservation, no “sudden” approximation • p-formation more reliable • To be resolved: • quark masses are not “constituent”: • role of gluons? (not really heavier than quarks…) , … -

  39. If c-quarks thermalize: [Grandchamp] * sensitivity tomc Npart 4.3 Charm II: Charmonium Regenerationin QGP / atTc J/y + g c + c + X - → ← • RHIC central: Ncc≈10-20, • QCD lattice: J/y’s to~2Tc [PBM etal, Thews etal]

  40. [Fries,Hwa,Molnar] [STAR] [PHENIX] [Greco et al.] universal partonic v2(pT/n) / n soft-soft≈thermal ( pT » m) soft-hard:explicitthermal+jet (correlations!) 3.4 Hydro vs. Coalescence: The 2-6GeV Regime [Hirano,Nara] v2: mass-dependent But: p/p(4GeV)≈0.3 [PHENIX]: 1±0.15 Challenges:p/p=1+ jet correlation , felliptic flow

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