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Article Dans Une Revue Phys.Rev.C Année : 2019

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

Résumé

Nonperturbative 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 nonperturbative 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⊗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 Ca42,48 and Ni68 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.

Dates et versions

hal-02303004 , version 1 (02-10-2019)

Identifiants

Citer

Elena Litvinova, Peter Schuck. Toward an accurate strongly-coupled many-body theory within the equation of motion framework. Phys.Rev.C, 2019, 100 (6), pp.064320. ⟨10.1103/PhysRevC.100.064320⟩. ⟨hal-02303004⟩
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