Dilepton production in heavy ion collisions at intermediate energies

Abstract

We present a unified description of the vector meson and dilepton production in elementary and in heavy ion reactions. The production of vector mesons ($\rho ,\omega$) is described via the excitation of nuclear resonances ($R$). The theoretical framework is an extended vector meson dominance model (eVMD). The treatment of the resonance decays $R⟼NV$ with arbitrary spin is covariant and kinematically complete. The eVMD includes thereby excited vector meson states in the transition form factors. This ensures correct asymptotics and provides a unified description of photonic and mesonic decays. The resonance model is successfully applied to the $\omega$ production in $p+p$ reactions. The same model is applied to the dilepton production in elementary reactions ($p+p,p+d$). Corresponding data are well reproduced. However, when the model is applied to heavy ion reactions in the BEVALAC/SIS energy range the experimental dilepton spectra measured by the DLS Collaboration are significantly underestimated at small invariant masses. As a possible solution of this problem the destruction of quantum interference in a dense medium is discussed. A decoherent emission through vector mesons decays enhances the corresponding dilepton yield in heavy ion reactions. In the vicinity of the $\rho /\omega$-peak the reproduction of the data requires further a substantial collisional broadening of the $\rho$ and in particular of the $\omega$ meson.

32 pages revtex, 19 figures, to appear in PRC

References in corpus (50)

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• Current correlation functions, QCD sum rules and vector mesons in baryonic matter
• Chiral Restoration in Hot and/or Dense Matter
• Evidence for a Soft Nuclear Equation-of-State from Kaon Production in Heavy Ion Collisions
• Probing the nuclear equation of state by $K^{+}$ production in heavy ion collisions
• Dielectron Cross Section Measurements in Nucleus-Nucleus Reactions at 1.0 A GeV
• Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV I: pion-induced results and hadronic parameters
• Dilepton Production at SPS Energies
• Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV II: photon-induced results
• P-Wave Polarization of the $\rho$-Meson and the Dilepton Spectrum in Dense Matter
• $\varphi$ and $\omega$ Meson Production in pp Reactions at $p_{lab}$=3.67 GeV/c
• Dilepton Spectra from Decays of Light Unflavored Mesons
• Comparison of eta and eta' production in the pp -> pp eta(eta') reactions near threshold
• Observation of $\rho /\omega$ Meson Modification in Nuclear Matter
• Properties of $\rho$ and $\omega$ Mesons at Finite Temperature and Density as Inferred from Experiment
• Near-Threshold eta Meson Production in Proton-Proton Collisions
• eta in the nuclear medium within a chiral unitary approach
• Intermediate mass excess of dilepton production in heavy ion collisions at BEVALAC energies
• Inclusive Dielectron Cross Sections in p+p and p+d Interactions at Beam Energies from 1.04 to 4.88 GeV
• Delays Associated with Elementary Processes in Nuclear Reaction Simulations
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• Modifications of the Rho Meson from the Virtual Pion Cloud in Hot and Dense Matter
• Meson Masses in Nuclear Matter
• Momentum Dependence of the Pion Cloud for Rho Mesons in Nuclear Matter
• Dilepton production and $m_T$-scaling at BEVALAC/SIS energies
• Near-Threshold Production of omega Mesons in the pp -> pp omega Reaction
• Heavy Meson Production in Proton-Nucleus Reactions with Empirical Spectral Functions
• Electromagnetic transition form factors and dilepton decay rates of nucleon resonances
• Low-mass dileptons and dropping rho meson mass
• Dilepton Production at SPS-energy Heavy Ion Collisions
• Production of $\omega$ mesons in proton-proton collisions
• Dilepton/Photon Production in Heavy Ion Collisions and the QCD Phase Transition
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• In-medium dependence and Coulomb effects of the pion production in heavy ion collisions
• Remarks on Delta Radiative and Dalitz Decays
• Coupling of Baryon Resonances to the $N\omega$ channel
• Study of conversion decays phi->etae+e-, eta->e+e-g and eta->pi+pi-e+e- at CMD-2
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• Dilepton production in proton-proton collisions at BEVALAC energies
• rho, omega, phi-Nucleon Scattering Lengths from QCD Sum Rules
• Isoscalar-Isovector Interferences in $\pi N\to N{e}^{+}{e}^{-}$ Reactions as a Probe of Baryon Resonance Dynamics
• Model independent constraints from vacuum and in-medium QCD Sum Rules
• Resonance lifetime in Boltzmann-Uehling-Uhlenbeck theory: observable consequences
• $e^{+}{e}^{-}$ production in $pA$ reactions at SIS energies
• $\rho /\omega$ properties from dilepton spectra in $pA$ reactions at 12 GeV
• Thermal Dileptons from Quark and Hadron Phases of an Expanding Fireball

Cited by in corpus (41)

• Kaon production in heavy ion reactions at intermediate energies
• Hadron properties in the nuclear medium
• Understanding transport simulations of heavy-ion collisions at 100 and 400 AMeV: Comparison of heavy ion transport codes under controlled conditions
• Comparison of heavy-ion transport simulations: Collision integral in a box
• Dielectron production in 12C+12C collisions at 2 AGeV with HADES
• Dilepton production and off-shell transport dynamics at SIS energies
• Origin of the low-mass electron pair excess in light nucleus-nucleus collisions
• The Chiral Restoration Transition of QCD and Low Mass Dileptons
• Comparison of heavy-ion transport simulations: Collision integral with pions and $\Delta$ resonances in a box
• Study of dielectron production in C+C collisions at 1 AGeV
• Towards a model-independent constraint of the high-density dependence of the symmetry energy
• The impact of energy conservation in transport models on the ${\pi }^{-}/{\pi }^{+}$ multiplicity ratio in heavy-ion collisions and the symmetry energy
• Comparison of Heavy-Ion Transport Simulations: Mean-field Dynamics in a Box
• Transport Theories for Heavy Ion Collisions in the 1 AGeV Regime
• Dilepton production in proton-induced reactions at SIS energies with the GiBUU transport model
• Neutron-proton elliptic flow difference as a probe for the high density dependence of the symmetry energy
• Precision study of the $\eta \to {\mu }^{+}{\mu }^{-}\gamma$ and $\omega \to {\mu }^{+}{\mu }^{-}{\pi }^0$ electromagnetic transition form-factors and of the $\rho \to {\mu }^{+}{\mu }^{-}$ line shape in NA60
• Transport approaches for the Description of Intermediate-Energy Heavy-Ion Collisions
• Progress of Quantum Molecular Dynamics model and its applications in Heavy Ion Collisions
• Production and evolution path of dileptons at HADES energies
• Once more on electromagnetic form factors of nucleons in extended vector meson dominance model
• Dilepton production in heavy-ion collisions with in-medium spectral functions of vector mesons
• Dilepton production in proton-proton and quasifree proton-neutron reactions at 1.25 GeV
• Flow probe of symmetry energy in relativistic heavy-ion reactions
• Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES
• The Vector Probe in Heavy-Ion Reactions
• Dilepton production at HADES: theoretical predictions
• Analysis of the exclusive final state npe${}^{+}$e${}^{-}$ in quasi-free np reaction
• Vector meson angular distributions in proton-proton collisions
• Dilepton production in nucleon-nucleon collisions reexamined
• One-body Langevin dynamics in heavy-ion collisions at intermediate energies
• Dilepton and vector meson production in elementary and in heavy ion reactions
• Dilepton production in pp and CC collisions with HADES
• In-Medium Properties of Hadrons - Observables II
• Dielectron Production in C+C Collisions at 1 GeV/u and the Solution to the DLS Puzzle
• Dilepton production at SIS energies with the GiBUU transport model
• Observation of the hindered electromagnetic Dalitz decay $\psi (3686)\to e^{+}{e}^{-}{\eta }_c$
• Dilepton production in elementary and in heavy ion reactions
• In-medium $\Delta (1232)$ potential, pion production in heavy-ion collisions and the symmetry energy
• Dilepton production at SIS energies
• Transport Model Comparison Studies of Intermediate-Energy Heavy-Ion Collisions