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.

Article: 28 pages, 19 figures

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Cited by in corpus (20)

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• Many-body correlations in nuclear superfluidity
• Microscopic response theory for strongly-coupled superfluid fermionic systems
• Damping of the isovector giant dipole resonance in ${}^{40,48}$Ca
• Particle-vibration coupling for giant resonances beyond the diagonal approximation
• Systematics of the low-energy electric dipole strength in the Sn isotopic chain
• Comparative analysis of formalisms and performances of three different beyond mean-field approaches
• Many-body approach to superfluid nuclei in axial geometry
• Nuclear superfluidity at finite temperature
• Many-body theory for quasiparticle states in superfluid fermionic systems
• Nuclear Shell Structure in a Finite-Temperature Relativistic Framework
• Temperature evolution of the nuclear shell structure and the dynamical nucleon effective mass
• Multipole responses in fissioning nuclei and their uncertainties
• Theory of nuclear collective vibrations
• Axially Deformed Proton-Neutron Relativistic Quasiparticle Finite Amplitude Method for Charge-Exchange Transitions
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