1 / 24

In-medium hadrons and chiral symmetry

Intermediate energy Machines (1 GeV). Relativistic heavy ion collisions. The Physics of High Baryon Density IPHC Strasbourg, september 19, 2006. G. Chanfray, IPN Lyon, IN2P3/CNRS, Université Lyon I. In-medium hadrons and chiral symmetry. Chiral restoration

pamelagriffin
Download Presentation

In-medium hadrons and chiral symmetry

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Intermediate energy Machines (1 GeV) Relativistic heavy ion collisions The Physics of High Baryon Density IPHC Strasbourg, september 19, 2006 G. Chanfray, IPN Lyon, IN2P3/CNRS, Université Lyon I In-medium hadrons and chiral symmetry • Chiral restoration • Nucleon structure/ confinement • Lattice QCD • Renormalization group Chiral dynamics In-medium hadrons Many-body problem

  2. Chiral symmetry breaking Pions (kaons): Goldstone bosons Quark condensate : order parameter (magnétisation) Hadron spectral function and chiral dynamics Equation of state at finite T and r Chiral symmetry restoration Modifications of QCD vacuum Hadrons =elementary excitations also modified HADRONIC SPECTRAL FUNCTIONS

  3. In the medium: Spectral functions of chiral partners should converge: Chiral dynamics? Fluctuation currentsHadrons THERMAL SUSCEPTIBILITY Hadron spectral function Current-current correlator

  4. Chiral restoration and hadron structure

  5. Open charm Light quark q fluctuating around a heavy color source: sensitive to the quark condensate (QCD sum rules): - Mechanism for the suppression of the PANDA/GSI Expériences Pions In-medium mass splitting generated by chiral dynamics Generated by chiral dynamics, linked to condensate evolution - Increase of D Dbar Production -Opening of Channels

  6. Compare susceptibilities associated with chiral partners Scalar (sigma) : Pseudoscalar (pion) : PSEUDOSCALAR SCALAR Scalar susceptibility : from the scalar correlatori.e.the correlator of the scalar quark density fluctuations QCD susceptibilities: fluctuations of the quark condensate

  7. subtract w-Meson in Normal Nuclear Matter New Data forg A → w X→ p0g X : [CBELSA/TAPS ‘05] • dropping w-mass!(mw )med ≈ 720MeV, (Gw)med ≈ 60MeV • consistent with (some) hadronic models • connection to baryon-no./chiral susceptibility? (s-wmixing) [Klingl etal ’97]

  8. Chiral effective theory The chiral invariant s field governs the evolution of the masses : we identify it with the sigma field of nuclear physics(M. Ericson, P. Guichon, G.C) Matter stability: include the scalar response of the nucleon (confinement) Interplay between nuclear structure, chiral dynamics and nucleon structure. Insight from lattice QCD

  9. SUSCEPTIBILITIES E / A Mean field (s + omega) PSEUDO SCALAR MASSES Total Nucleon SCALAR Sigma Sigma + chiral dropping Fock The sigma mass remains stable DENSITY Fixing the parameters (nucleon susceptibility) using lattice data Msigma=800 MeV Gv=7.3 C=1+ Density dependence Higher densities ? Phase transition to quark matter ?

  10. Tostudy phase transition to quark matter: chiral theory Incorporating confinement at the quark level Attempt (Lawley, Bentz, Thomas): NJL model including diquark interaction and (kind of) confinement • Low T, r:Spontaneous chiral symmetry breaking : quark condensate • Nucleon : Quark + diquark bound state, confinement generates a scalar susceptibility • Stable nuclear matter • High r : pairing and diquark condensate: color superconducting phase Neutron star Phases of matter in b equilibrium

  11. Towards High baryonic densites ISSUES - Chiral symmetry restoration and deconfinement - (Tri)critical point? - Hadrons near phase transition ? SIGNATURES - Bulk thermodynamic variables - In-medium hadron spectral functions - Charm, dileptons THEORETICAL TOOLS - Lattice QCD at finite m - Effective theories - Renormalization group HEAVY IONS : 10- 40 A.GeV FAIR/CBM

  12. Dilepton production rDominance Current current correlator In the vector channel • Theoretical approaches • Density expansion • Many-body approaches • Transport codes • QCD sum rules • Weinberg sum rules • ……… • Renormalization group

  13. 0 at chiral restoration Vector and axialvector spectral functions Associated with chiral partnersr -a1(1260) Chiral restoration means : vector and axialvector correlation functions become identical An illustration : Weinberg sum rule

  14. Axialvector / Vector in Vacuum pQCD continuum ImPem~ [ImDr+ImDw /10+ImDf /5] Axialvector / Vector near Tc Axialvector / Vector at finite density Axial =Vector + 1 pion from the medium • Low-Mass Dilepton Rate: r -meson dominated! • Axialvector Channel:p±ginvariant mass-spectra~ Im Da1(M) ?!

  15. Top SPS Energy Lower SPS Energy Pb-Au collisions at CERN/SPS : CERES/NA45 → Evolve dilepton rates over thermal fireball QGP+Mix+HG (Rapp et al): r meson melts in dense matter Baryon density more important than temperature (40A. GeV vs 158A. GeV) Hades data/ Futur GSI: CBM (~ 30A.GeV) QGP contribution small Medium effects on r meson

  16. In-In collisions at CERN/SPS: dimuons from NA60 NA60 has    extracted  the rho meson spectral function Free spectral function ruled out Meson gas insufficient Consistent with the modification (broadening) of the rho meson spectral function (Rapp-Wambach/Chanfray ) Simplistic dropping mass ruled out

  17. HADES data

  18. One particular Model exemple(HLS) r gauge boson of a hidden local symmetry Matching of the correlators at : Renormalization group equations Perspectives Strong constraints on effective theories( EFT) Lattice data at finite m Renormalization group Matching of EFT to QCD Fate of VDM at finite T and m ? Brown-Rho scaling near phase transition ?

  19. Conclusions Chiral invariant scalar mode = amplitude fluctuation of the condensate - Sigma mass stabilized by confinement effect in hadronic phase Dilepton production : broadening of the rho meson dominated by baryonic effects but - Fate of vector dominance ? - Dropping of the rho mass ? - Through its coupling to the condensate: from the dropping of the sigma mass near the critical point (Shuryak)

  20. 3.5.3 NA60 Data: Other r-Spectral Functions Chiral Virial Approach Switch off medium modifications [Dusling,Teaney+Zahed ‘06] • free spectral function ruled out • meson gas insufficient either • lacks broadening • simplistic dropping mass disfavored: • vector manifest. of c-symmetry? vector dominance? [Harada+Yamawaki, Brown+Rho ‘04]

  21. subtract w-Meson in Normal Nuclear Matter New Data forg A → w X→ p0g X : [CBELSA/TAPS ‘05] • dropping w-mass!(mw )med ≈ 720MeV, (Gw)med ≈ 60MeV • consistent with (some) hadronic models • connection to baryon-no./chiral susceptibility? (s-wmixing) [Klingl etal ’97]

  22. Pions In-medium mass splitting generated by chiral dynamics Pattern of symmetry breaking generated by chiral dynamics

  23. Axial-vector mixing at finite temperature

More Related