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Light and Heavy Hadrons in Medium

Light and Heavy Hadrons in Medium. Ralf Rapp Cyclotron Inst. and Physics Dept. Texas A&M University College Station, USA Frankfurt am Main, 25.06.04. c PT many-body degrees of freedom? QGP (2 ↔ 2) (3-body,...) (resonances?)

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Light and Heavy Hadrons in Medium

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  1. Light and Heavy Hadrons in Medium Ralf Rapp Cyclotron Inst. and Physics Dept. Texas A&M University College Station, USA Frankfurt am Main, 25.06.04

  2. cPTmany-bodydegrees of freedom?QGP (2 ↔ 2)(3-body,...) (resonances?) consistentextrapolatepQCD 0 0.05 0.3 0.75 e[GeVfm-3] 120 150-160 175 T [MeV] ½r0 2r0 5r0rhadron 1.Introduction:Towards the Phase Transition • Description of Chiral Symmetry Restoration / Decofinement • requires nonperturbative approaches • Mean-field models (lin. s-model, NJL) capture many aspects, • but incomplete (limited d.o.f., only mass effects,…) note: high-density CFL phase (CSC) characterized by “hadronic” excitations (“p”, “r”, …)

  3. Outline 1. Introduction 2. Hadrons below Tc 2.1 Light Hadrons: Vacuum 2.2 Hadronic Many-Body Approach: u,d Sector - Mesons: 0± (p-s), 1± (r-a1), Baryons: D(1232) - Consistency and Constraints (Nuclei, Lattice, …) - Towards a Chiral + Resonance Scheme - URHIC’s 2.3 Charmed Mesons 3. “Hadrons” at and above Tc 3.1 Continuity ?! 3.2 Heavy Quarks: Charmonium Regeneration 3.3 Light Quarks: Generalization of Coalescence 4. Conclusions

  4. 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

  5. p and dF2 Structure Functions Jlab Data x=2x/(1+√1+4M2x2/Q2) (Nachtmann Variable) average → “Quark-Hadron Duality” [Niculescu etal. ’00] (ii) Light Sector in Vacuum II: Spacelike Constituent Quark Mass “Data”: lattice [Bowman etal ‘02] Curve: Instanton Model [Diakonov+ Petrov ’85, Shuryak]

  6. 2.2 Hadronic Many-Body Approach:Light Sector (u,d) 2.2.1 0± Mesons: Pion and “Sigma” 2.2.2 1± : Rho and a1(1260) 2.2.3 Chiral + Resonance Scheme 2.2.4 Baryons: D(1232) 2.2.5 Comparison to Lattice 2.2.6 URHICs: E.M. Probes and Resonances

  7. “s”→p at Tc Precursor in nuclei ?! pA→(pp)S-WaveA > Sp = + > URHICs:- fluct. Ps(0,q→0) - ppM-spectra - (very) soft photons 2.2.1 Pion and Sigma in Medium Dp=[k02-wk2-Sp(k0,k)]-1 N,Dp N-1,D-1 • finiterNprevalent • “diluted” atT>0

  8. 2.2.2 1± Mesons: r Sp > Sp > Significance of high rB at low M Elab=20-40AGeV optimal?! (i) r(770) B*,a1,K1... Constraints: - branching ratiosB,M→rN,rp -gN,gAabsorpt.,pN→rN - QCD sum rules + N,p,K…

  9. (ii) Vector Mesons at RHIC baryon effects important even at rB,tot=0 : sensitive to rBtot=rB+rB , f more robust ↔ OZI -

  10. > 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)

  11. pS pS pS pS pS pP pP 2.2.3 Towards a Chiral + Resonance Scheme Options for resonance implementation: (i) generate dynamically from pion cloud [Lutz et al. ‘03, …] (ii) genuine resonances on quark level → representations of chiral group [DeTar+Kunihiro ‘89, e.g. Jido etal ‘00, …] 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!

  12. 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 > > 2.2.4 In-Medium Baryons: D(1232) long history in nuclear physics ! (pA , gA ) e.g. nuclear photoabsorption:MD, GDup by 20MeV  little attention at finite temperature  D-Propagator at finite rB and T[van Hees + RR ’04]

  13. (i) Check: D in Vacuum and in Nuclei → ok !

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

  15. [Laermann, Karsch ’04] 1- MEM 0- extracted 2.2.5 Lattice Studies of Medium Effects calculated on lattice p more stable than r below Tc?! (but: quenched)

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

  17. Im Πem(M,q) Im Πem(q0=q) [Turbide,Gale+RR ’03] • consistent with dileptons • pp Brems with soft s at low q? 2.2.6 Observables in URHICs e+ e- γ (i) Lepton Pairs(ii) Photons baryon density effects!

  18. 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]

  19. pN smean-field: (iv) Resonance Spectroscopy II : p+p Spectra D(1232) at RHIC [courtesy P. Fachini] Qualitatively in line with data (DMD=8MeV ,DGD=55MeV) DMD=+22MeV DGD =+(45±10)MeV

  20. - - p + J/y → DD,D*D QCD-SR Mes-Ex CQM pQCD 2.3 Charm(onium) below Tc Dissociation rate [Grandchamp+RR ’03] Reduced DD threshold: DmD(Tc)≈-140MeV (NJL)   J/y robust  Y’ fragile: direct Y’→ DD decays

  21. 3. “Hadrons” at and Above Tc 3.1 Continuity ?! 3.2 Charmonium in QGP 3.3 Light Hadrons in QGP

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

  23. if c-quarks thermalize include back-channel : “jumps” across Tc sensitive to mc* 3.2 Charmonium in QGP Dy=[M2-my2-Sy]-1 , my≈const (QCD-SR, LGT) gluo-dissociation, inefficient for my≈ 2 mc* “quasifree” diss. [Grandchamp+RR ’01]

  24. J/yExcitation Function SPSRHIC Charmonia in URHIC’s [Grandchamp +RR ’03]

  25. 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…) , … -

  26. 4. 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

  27. Additional Slides

  28. [PHENIX] preliminary [PHENIX] preliminary 4.3 Charm I: Open Charm (Central A-A) (i) Yields • RHIC:-30% for h=02: CGC[Tuchin], Color-Dipole [Raufeisen] • LHC:CGC: Npart; nonlin. DGLAP:enhanced! [Kolhinen] (ii) pT-Spectra dE/dx: Null Effect?![Djordjevic] v2(e±) :Thermalization?!

  29. [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

  30. 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

  31. 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]

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