The Chiral Restoration Transition of QCD and Low Mass Dileptons

Abstract

Recent developments in the evaluation of vector-meson spectral functions in hot and dense matter are discussed with emphasis on connections to the chiral phase transition in QCD. Model independent approaches including chiral low-density expansions, lattice QCD, chiral and QCD sum rules are put into context with model predictions for in-medium vector-spectral function utilizing effective Lagrangians. Hadronic many-body calculations predict a strong broadening (and little mass shift) of the $\rho$ spectral function which rapidly increases close to the expected phase boundary of hadronic and quark-gluon matter. Pertinent dilepton rates appear to degenerate with perturbative quark-antiquark annihilation in the Quark-Gluon Plasma, suggestive for chiral symmetry restoration. Applications to low-mass dilepton spectra in heavy-ion collisions result in quantitative agreement with recent high-quality data at the CERN-SPS. Thermal radiation from temperatures around $T_c$ consistently reproduces the experimental dilepton excess observed at masses above 1 GeV as well. The interpretation of dilepton sources at high transverse momentum appears to be more involved.

48 pages, 59 ps/eps figures

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• Study of the electromagnetic transition form-factors in η-> μ^+μ^-γand ω-> μ^+μ^-π^0 decays with NA60
• Status and initial physics performance studies of the MPD experiment at NICA
• Pseudo-Critical Enhancement of Thermal Photons in Relativistic Heavy-Ion Collisions
• Design, Construction, Operation and Performance of a Hadron Blind Detector for the PHENIX Experiment
• Thermal dilepton rates and electrical conductivity of the QGP from the lattice
• Thermal Dileptons from Coarse-Grained Transport as Fireball Probes at SIS Energies
• Inclusive dielectron spectra in p+p collisions at 3.5 GeV
• Electromagnetic radiation as a probe of the initial state and of viscous dynamics in relativistic nuclear collisions
• Effects of $\rho$-meson width on pion distributions in heavy-ion collisions
• The emission of electromagnetic radiation from the early stages of relativistic heavy-ion collisions
• Thermal photon emission from the pi-rho-omega system
• The STAR Dilepton Physics Program
• Virtual Photons Shed Light on the Early Temperature of Dense QCD Matter
• Parity doubling of baryons in a chiral approach with three flavors
• Properties of Thermal Photons at RHIC and LHC
• Low Mass Dilepton Rate from the Deconfined Phase
• Dielectron production in proton-proton collisions at $\sqrt{s}$ = 7 TeV
• In-medium spectral functions and dilepton rates with the Functional Renormalization Group
• Dilepton Signature of a First-Order Phase Transition
• Fluctuating vector mesons in analytically continued FRG flow equations
• In-Medium Vector Mesons, Dileptons and Chiral Restoration
• Dielectron production in proton-proton and proton-lead collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV
• The low and intermediate mass dilepton and photon results
• Medium Modifications of the Rho Meson in Nuclear Photoproduction
• Radiation of an electric charge in the field of a magnetic monopole
• Exploring the properties of the phases of QCD matter - research opportunities and priorities for the next decade
• In-medium vector mesons and low mass lepton pairs from heavy ion collisions
• Role of baryon resonances in the ${\pi }^{-}p\to n{e}^{+}{e}^{-}$ reaction within an effective-Lagrangian model
• In the Pursuit of $X(5568)$ and its Charmed Partner
• $\varphi$ meson production at forward rapidity in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV
• Hadron Blind Cherenkov Counters
• Review of opportunities at the HESR-Collider with PANDA at FAIR
• Resonances as Probes of Heavy-Ion Collisions at ALICE
• Heavy Flavor, Quarkonia, and Electroweak Probes at Quark Matter 2012
• Thermal dilepton rates from quenched lattice QCD
• Interactions of $\omega$-Mesons in Nuclear Matter and with Nuclei
• Dilepton Spectroscopy of QCD Matter at Collider Energies
• Recent ALICE results on hadronic resonance production
• Chiral symmetry and open-charm mesons
• Temperature dependence of electrical conductivity and dilepton rates from hot quenched lattice QCD
• Future perspectives at SIS-100 with HADES-at-FAIR
• Dilepton Production in Heavy-Ion Collisions
• Application of radial basis functions neutral networks in spectral functions
• Photon emissivity in the vicinity of a critical point - A case study within the quark meson model
• Measurements of the electron-positron continuum in ALICE
• Imprints of a critical point on photon emission
• Photons from relativistic nuclear collisions
• Theory of Soft Electromagnetic Emission in Heavy-Ion Collisions
• Chiral Symmetry Breaking, Trace Anomaly and Baryons in Hot and Dense Matter
• Probing resonance matter with virtual photons
• Low-mass dielectron measurement in pp and Pb--Pb collisions in ALICE
• Soft pions and transport near the chiral critical point
• Chiral symmetry, di-electrons and charm
• Photon emission rates near the critical point in the linear sigma model