|July 11, 2023 - 11:00
|Guest House, GANIL, Caen | France
Elena Litvinova (Western Michigan University and Michigan State University, USA)
The nuclear many-body problem formulated in terms of the fermionic correlation functions (CFs), or propagators, will be discussed. Starting from the ab-initio Hamiltonian, the CFs are quantified within a systematic equation-of-motion (EOM) framework. Furthermore, the coupled one-fermion and two-fermion propagators, mostly relevant for the nuclear ground and excited states, can be decoupled from the rest of the CFs hierarchy by approximations with minimal truncations, which keep the leading effects of emergent collectivity. The approach is implemented numerically for the nuclear single-particle states and nuclear response, on the basis of the relativistic effective meson-nucleon Lagrangian. It is shown that the coupling between the CFs of the single Bogoliubov’s quasiparticles (q) and their correlated pairs (phonons) improves systematically the description of the single-particle states, as compared to the Hartree-Fock-Bogoliubov approach, in both spherical and axially deformed nuclei. The 2q⊗phonon configurations beyond the standard (quasiparticle) random phase approximation help improve the description of the nuclear excitations, in both the gross and fine structure aspects, such as the centroids and widths of the giant resonances, and the low-energy strength distributions. It is shown that the higher-rank 2q⊗2phonon configurations and backward-going 2q⊗phonon terms in the dynamical kernel of the response EOM may further refine the excitation spectra. Such nuclear structure phenomena as the giant dipole and monopole resonances, pygmy resonances, Gamow-Teller resonance and beta decay will be addressed within the self-consistent implementation based on the universal covariant parametrization across the nuclear chart.