Toward an accurate strongly-coupled many-body theory within the equation of motion framework

Abstract

Non-perturbative aspects of the quantum many-body problem are revisited, discussed and advanced in the equation of motion framework. We compare the approach to the two-fermion response function truncated on the two-body level by the cluster expansion of the dynamical interaction kernel to the approach known as time blocking approximation. Such a comparison leads to an extended many-body theory with non-perturbative treatment of high-order configurations. The present implementation of the advanced theory introduces a new class of solutions for the response functions, which include explicitly beyond-mean-field correlations between up to six fermions. The novel approach, which includes configurations with two quasiparticles coupled to two phonons (2q$\otimes$2phonon), is discussed in detail for the particle-hole nuclear response and applied to medium-mass nuclei. The proposed developments are implemented numerically on the basis of the relativistic effective meson-nucleon Lagrangian and compared to the models confined by two-fermion and four-fermion configurations, which are considered as state-of-the-art for the response theory in nuclear structure calculations. The results obtained for the dipole response of ${}^{42,48}$Ca and ${}^{68}$Ni nuclei in comparison to available experimental data show that the higher configurations are necessary for a successful description of both gross and fine details of the spectra in both high-energy and low-energy sectors.

arXiv commentArticle: 28 pages, 19 figures

References in corpus (51)

• A New Parameterization for the Lagrangian Density of Relativistic Mean Field Theory
• Exotic modes of excitation in atomic nuclei far from stability
• Relativistic Nuclear Energy Density Functionals: adjusting parameters to binding energies
• Complete electric dipole response and the neutron skin in 208Pb
• The In-Medium Similarity Renormalization Group: A Novel Ab Initio Method for Nuclei
• Nuclear Ground State Observables and QCD Scaling in a Refined Relativistic Point Coupling Model
• Quasiparticle random phase approximation based on the relativistic Hartree-Bogoliubov model
• The Compression-Mode Giant Resonances and Nuclear Incompressibility
• Isospin Character of the Pygmy Dipole Resonance in 124Sn
• Relativistic quasiparticle time blocking approximation. Dipole response of open-shell nuclei
• Covariant theory of particle-vibrational coupling and its effect on the single-particle spectrum
• QRPA plus Phonon Coupling Model and the Photoabsorbtion Cross Section for ${}^{18,20,22}$O
• Quasiparticle time blocking approximation within the framework of generalized Green function formalism
• Particle-vibration coupling within covariant density functional theory
• Mode-coupling and the pygmy dipole resonance in a relativistic two-phonon model
• Low-lying dipole response in the Relativistic Quasiparticle Time Blocking Approximation and its influence on neutron capture cross sections
• Neutral and charged excitations in carbon fullerenes from first-principles many-body theories
• Subtraction method and stability condition in the extended RPA theories
• Particle-vibration coupling effect on the $\beta$-decay of magic nuclei
• Relativistic quasiparticle time blocking approximation. II. Pygmy dipole resonance in neutron-rich nuclei
• Collective nuclear excitations with Skyrme-Second RPA
• Second RPA and correlated realistic interactions
• Low-lying dipole response in the stable ${}^{40,48}$Ca nuclei with the second random-phase approximation
• The Gamow-Teller response within Skyrme random-phase approximation plus particle-vibration coupling
• Relativistic RPA plus phonon-coupling analysis of pygmy dipole resonances
• Large-scale second RPA calculations with finite-range interactions
• Low-energy dipole strength in 112,120Sn
• Population of dipole states via isoscalar probes: the splitting of pygmy dipole resonance in ${}^{124}$Sn}
• Fully self-consistent relativistic Brueckner-Hartree-Fock theory for finite nuclei
• Isospin properties of electric dipole excitations in 48Ca
• Nuclear response theory for spin-isospin excitations in a relativistic quasiparticle-phonon coupling framework
• Fine structure of the isovector giant dipole resonance in 208Pb: Characteristic scales and level densities
• Relativistic two-phonon model for low-energy nuclear response
• Gamow-Teller response and its spreading mechanism in doubly magic nuclei
• Description of electric dipole excitations in the tin isotopes within the quasiparticle time blocking approximation
• Electric dipole response of neutron-rich Calcium isotopes in relativistic quasiparticle time blocking approximation
• Time-reversed particle-vibration loops and nuclear Gamow-Teller response
• Fragmentation of spin-dipole strength in ${}^{90}$Zr and ${}^{208}$Pb
• Application of an Extended Random Phase Approximation on Giant Resonances in Light, Medium and Heavy Mass Nuclei
• Coupling charge-exchange vibrations to nucleons in a relativistic framework: effect on Gamow-Teller transitions and beta-decay half-lives
• Progress in Many Body Theory with the Equation of Motion method. Time dependent Density Matrix meets Self-Consistent RPA. Applications to solvable Models
• Nuclear response theory with multiphonon coupling in a covariant framework
• Self-consistency in the phonon space of the particle-phonon coupling model
• Collective response of nuclei: Comparison between experiments and extended mean-field calculations
• Doubly magic nuclei from Lattice QCD forces at $M_{PS}=$469 MeV/c${}^2$
• A formally exact one-frequency-only Bethe-Salpeter-like equation. Similarities and differences between GW +BSE and self-consistent RPA
• Strong fragmentation of low-energy electromagnetic excitation strength in ${}^{117}$Sn
• Isoscalar and neutron modes in the E1 spectra of Ni isotopes and the relevance of shell effects and the continuum
• Pion-nucleon correlations in finite nuclei in a relativistic framework: effects on the shell structure
• Sum-rules and Goldstone modes from extended RPA theories in Fermi systems with spontaneously broken symmetries
• Self-consistent calculations within the Green's function method including particle-phonon coupling and the single-particle continuum

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