Dilepton bremsstrahlung from pion-pion scattering in a relativistic one boson exchange model

Eggers, H. C.; Tabti, R.; Gale, Charles; Haglin, Kevin

doi:10.1103/physrevd.53.4822

Cited by 22 publications

(35 citation statements)

References 41 publications

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“…|y e | ≤ 1. We note that dielectron Bremsstrahlung from both partonic and hadronic collisions -as suggested long ago [16][17][18][19][20][21] -is added to our previous study [7], although the contributions are subleading. For an estimate of the order of magnitude the differential Bremsstrahlung cross section is evaluated in the soft-photon approximation:…”

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confidence: 99%

Discrepancy in low transverse momentum dileptons from relativistic heavy-ion collisions

et al. 2018

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The dilepton transverse momentum spectra and invariant mass spectra for low pT < 0.15 GeV/c in Au+Au collisions of different centralities at √ sNN = 200 GeV are studied within the partonhadron-string dynamics (PHSD) transport approach. The PHSD describes the whole evolution of the system on a microscopic basis, incorporates hadronic and partonic degrees-of-freedom, the dynamical hadronization of partons and hadronic rescattering. For dilepton production in p+p, p+A and A+A reactions the PHSD incorporates the leading hadronic and partonic channels (also for heavy flavors) and includes in-medium effects such as a broadening of the vector meson spectral functions in hadronic matter and a modification of initial heavy-flavor correlations by interactions with the partonic and hadronic medium. The transport calculations reproduce well the momentum integrated invariant mass spectra from the STAR Collaboration for minimum bias Au+Au collisions at √ sNN = 200 GeV, while the description of the STAR data -when gating on low pT < 0.15 GeV/c -is getting worse when going from central to peripheral collisions. An analysis of the transverse momentum spectra shows that the data for peripheral (60-80%) collisions are well reproduced for pT > 0.2 GeV/c while the strong peak at low pT < 0.15 GeV/c, that shows up in the experimental data for the mass bins (0.4 < M < 0.7 GeV and 1.2 < M < 2.6 GeV), is fully missed by the PHSD and cannot be explained by the standard in-medium effects. This provides a new puzzle for microscopic descriptions of low pT dilepton data from the STAR Collaboration.

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confidence: 99%

Discrepancy in low transverse momentum dileptons from relativistic heavy-ion collisions

et al. 2018

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“…(1)(2) in Sec.II with initial conditions obtained from SSPC model [3]. One can see that our results for the nonequilibrium soft photon (19) and low mass dileptons (15) due to bremsstrahlung differ from that of equilibrium rates. We would like to point out here that we cannot make a comparison of nonequilibrium results with that of equilibrium one as the present study is intended for RHIC and LHC energies.…”

Section: Resultsmentioning

confidence: 81%

Soft electromagnetic radiations from an equilibrating quark-gluon plasma

Pal

Mustafa

1999

Phys. Rev. C

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We evaluate the bremsstrahlung production of low mass dileptons and soft photons from equilibrating and transversely expanding quark gluon plasma which may be created in the wake of relativistic heavy ion collisions. We use initial conditions obtained from the self screened parton cascade model. We consider a boost invariant longitudinal and cylindrically symmetric transverse expansion of the parton plasma and find that for low mass dileptons ( M ≤ 0.3 GeV) and soft photons ( pT ≤ 0.5 GeV), the bremsstrahlung contribution is rather large compared to annihilation process at both RHIC and LHC energies. We also find an increase by a factor of 15-20 in the low mass dileptons and soft photons yield as one goes from RHIC to LHC energies.

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“…[130]. Alternatively, one can take into account additional diagrams with the emission of photons from the internal lines (see Refs [129]) but this method does not always eliminate the need for contact terms (see Ref. [135]).…”

Section: Bremsstrahlung M + M → M + M + γ Beyond the Soft-photon Apprmentioning

confidence: 99%

Effective QCD and transport description of dilepton and photon production in heavy-ion collisions and elementary processes

Linnyk

Bratkovskaya

Cassing

2016

Progress in Particle and Nuclear Physics

144

108

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In this review we address the dynamics of relativistic heavy-ion reactions and in particular the information obtained from electromagnetic probes that stem from the partonic and hadronic phases. The out-of-equilibrium description of strongly interacting relativistic fields is based on the theory of Kadanoff and Baym. For the modeling of the partonic phase we introduce an effective dynamical quasiparticle model (DQPM) for QCD in equilibrium. In the DQPM, the widths and masses of the dynamical quasiparticles are controlled by transport coefficients that can be compared to the corresponding quantities from lattice QCD. The resulting off-shell transport approach is denoted by Parton-Hadron-String Dynamics (PHSD) which includes covariant dynamical transition rates for hadronization and keeps track of the hadronic interactions in the final phase. It is shown that the PHSD captures the bulk dynamics of heavy-ion collisions from lower SPS to LHC energies and thus provides a solid basis for the evaluation of the electromagnetic emissivity on the basis of the same dynamical parton propagators that are employed for the dynamical evolution of the partonic system. The production of direct photons in elementary processes and heavy-ion reactions is discussed and the present status of the photon v 2 "puzzle" -a large elliptic flow v 2 of the direct photons experimentally observed in heavy-ion collisions -is addressed for nucleus-nucleus reactions at RHIC and LHC energies. The role of hadronic and partonic sources for the photon spectra and the flow coefficients v 2 and v 3 are considered as well as the possibility to subtract the QGP signal from the experimental observables. Furthermore, the production of e + e − or µ + µ − pairs in elementary processes and A+A reactions is addressed. The calculations within the PHSD from SIS to LHC energies show an increase of the low mass dilepton yield essentially due to the in-medium modification of the ρ-meson and at the lowest energy also due to a multiple regeneration of ∆-resonances. Furthermore, pronounced traces of the partonic degrees-of-freedom are found in the intermediate dilepton mass regime (1.2 GeV < M < 3 GeV) at relativistic energies, which will also shed light on the nature of the very early degrees-of-freedom in nucleus-nucleus collisions.

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Dilepton bremsstrahlung from pion-pion scattering in a relativistic one boson exchange model

Cited by 22 publications

References 41 publications

Discrepancy in low transverse momentum dileptons from relativistic heavy-ion collisions

Discrepancy in low transverse momentum dileptons from relativistic heavy-ion collisions

Soft electromagnetic radiations from an equilibrating quark-gluon plasma

Effective QCD and transport description of dilepton and photon production in heavy-ion collisions and elementary processes

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