Effect of exchange currents in E1 sum rule and orbital g-factor in 209Bi

A simple relation between the effective parameters of chiral Lagrangians in medium as predicted by BR scaling and Landau Fermi liquid parameters is derived. This provides a link between an effective theory of QCD at mean-field level and many-body theory of nuclear matter. It connects in particular the scaling vector-meson mass probed by dileptons produced in heavy-ion collisions (e.g., CERES of CERN-SPS) to the scaling nucleon-mass relevant for low-energy spectroscopic properties, e.g., the nuclear gyromagnetic ratios δg l and the effective axial-vector constant g ⋆ A .

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“…This is in agreement with the result [41] for protons extracted from the dipole sum rule in 209 Bi using the Fujita-Hirata relation [42]:…”

Section: Predictionsupporting

confidence: 91%

From chiral Lagrangians to Landau-Fermi liquid theory of nuclear matter

1996

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“…Despite these encouraging results, the Fermi liquid parameter F 0 remained well below −1, giving rise to a negative compression modulus K and a corresponding instability of nuclear matter against density fluctuations in the vicinity of saturation density ρ 0 = 0.16 fm −3 . Additionally, the anomalous orbital g-factor decreased from δg l ≃ 0.3 to δg l ≃ 0.1, which is significantly less than the empirical value δg l = 0.20 − 0.26 extracted from giant dipole resonances [32]. This feature followed almost entirely from the dramatic increase in the effective mass M * at second…”

Section: Nuclear Quasiparticle Interactionmentioning

confidence: 63%

Quasiparticle interaction in nuclear matter with chiral three-nucleon forces

2012

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We derive the effective interaction between two quasiparticles in symmetric nuclear matter resulting from the leading-order chiral three-nucleon force. We restrict our study to the L = 0, 1 Landau parameters of the central quasiparticle interaction computed to first order. We find that the three-nucleon force provides substantial repulsion in the isotropic spin-and isospin-independent component F 0 of the interaction. This repulsion acts to stabilize nuclear matter against isoscalar density oscillations, a feature which is absent in calculations employing low-momentum two-nucleon interactions only. We find a rather large uncertainty for the nuclear compression modulus K due to a sensitive dependence on the low-energy constant c 3 . The effective nucleon mass M * on the Fermi surface, as well as the nuclear symmetry energy β, receive only small corrections from the leading-order chiral three-body force. Both the anomalous orbital g-factor δg l and the Landau-Migdal parameter g ′ N N (characterizing the spin-isospin response of nuclear matter) decrease with the addition of three-nucleon correlations.In fact, δg l remains significantly smaller than its value extracted from experimental data, whereas g ′

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“…These experiments were restricted to energies from about 5 MeV [61] to 17.4 MeV [63]. The high energy-resolution was of essential help in cases where Compton scattered photons had to be discriminated from photons stemming from nuclear resonance fluorescence or nuclear Raman scattering.…”

Section: Nuclear Compton Scattering Experiments From the Mid-1970th Tmentioning

confidence: 99%

“…sections 3.3 and 7). It turns out that the giant-resonance part of the mesonic seagull amplitude is closely related to the in-medium mass of the nucleon [63,66,[86][87][88][89][90][91][92][93][94][95][96][97] which is a special case of the general Brown and Rho scaling [91][92][93][94][96][97][98]. One motivation to study nuclear Compton scattering, therefore, is to get further insight into the properties of the in-medium mass of the nucleon.…”

Section: Motivations For Studying Nuclear Compton Scatteringmentioning

confidence: 99%

“…As a result the determination of the Compton differential cross section only depends on the relative rates of incoming and scattered photons and makes this method a favorable tool to scale the photon-neutron data. One experiment of this type has been carried for 209 Bi [63], being an immediate neighbor of 208 Pb. The advantage of investigating 209 Bi instead of 208 Pb is, that because of the much higher level density the cross section is a smooth function of energy whereas that of 208 Pb is rather fragmented [64].…”

Section: Scaling Of Giant Resonance Parameters Via Compton Scatteringmentioning

confidence: 99%

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Compton scattering by nuclei

et al. 2000

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The concept of Compton scattering by even-even nuclei from giant-resonance to nucleon-resonance energies and the status of experimental and theoretical researches in this field are outlined. The description of Compton scattering by nuclei starts from different complementary approaches, namely from second-order S-matrix and from dispersion theories. Making use of these, it is possible to incorporate into the predicted nuclear scattering amplitudes all the information available from other channels, viz. photon-nucleon and photon-meson channels, and to efficiently make use of models of the nucleon, the nucleus and the nucleon-nucleon interaction. The total photoabsorption cross section constrains the nuclear scattering amplitude in the forward direction. The specific information obtained from Compton scattering therefore stems from the angular dependence of the nuclear scattering amplitude, providing detailed insight into the dynamics of the nuclear and nucleon degrees of freedom and into the interplay between them. Nuclear Compton scattering in the giant-resonance energy-region provides information on the dynamical properties of the in-medium mass of the nucleon. Most prominently, the electromagnetic polarizabilities of the nucleon in the nuclear medium can be extracted from nuclear Compton scattering data obtained in the quasideuteron energy-region. In our description of this latter process special emphasis is laid upon the exploration of many-body and two-body effects entering into the nuclear dynamics. Recent results are presented for two-body effects due to the mesonic seagull amplitude and due to the excitation of nucleon internal degrees of freedom accompanied by meson exchanges. Due to these studies the inmedium electromagnetic polarizabilities are by now well understood, whereas the understanding of nuclear Compton scattering in the ∆-resonance range is only at the beginning. Furthermore, phenomenological methods how to include retardation effects in the scattering amplitude are discussed and compared with model predictions.

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Effect of exchange currents in E1 sum rule and orbital g-factor in 209Bi

Cited by 35 publications

References 10 publications

From chiral Lagrangians to Landau-Fermi liquid theory of nuclear matter

From chiral Lagrangians to Landau-Fermi liquid theory of nuclear matter

Quasiparticle interaction in nuclear matter with chiral three-nucleon forces

Compton scattering by nuclei

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