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Nuclear Theory·nucl-th

Wednesday·August 16, 2023

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    On the dynamical kernels of fermionic equations of motion in strongly-correlated media

    Elena Litvinova🇺🇸

    Two-point fermionic propagators in strongly-correlated media are considered with an emphasis on the dynamical interaction kernels of their equations of motion (EOM). With the many-body Hamiltonian confined by a two-body interaction, the EOMs for the two-point fermionic propagators acquire the Dyson form and, before taking any approximation, the interaction kernels decompose into the static and dynamical (time-dependent) contributions. The latter translate to the energy-dependent and the former map to the energy-independent terms in the energy domain. We dwell particularly on the energy-dependent terms, which generate long-range correlations while making feedback on their short-range static counterparts. The origin, forms, and various approximations for the dynamical kernels of one-fermion and two-fermion propagators, most relevant in the intermediate-coupling regime, are discussed. Applications to the electromagnetic dipole response of Ni and low-energy quadrupole response of Sn are presented.

    nucl-thcond-mat.othernucl-exEPJA(2023)·13 citations
  2. 02

    Open Quantum Systems with Kadanoff-Baym Equations

    Tim Neidig🇩🇪 · Jan Rais🇩🇪 · Marcus Bleicher🇩🇪 · Hendrik van Hees🇩🇪 · Carsten Greiner🇩🇪

    We study the temporal evolution of quantum mechanical fermionic particles exhibiting one bound state within a one-dimensional attractive square-well potential in a heat bath of bosonic particles. For this open quantum system we formulate the non-equilibrium Kadanoff-Baym equations for the system particles by taking the interactions to be elastic 2-2 scatterings with the heat-bath particles. The corresponding spatially imhomogeneous integro-differential equations for the one-particle Greens's function are solved numerically. We demonstrate how the system particles equilibrate and thermalize with the heat bath and how the off-diagonal elements of the density matrix, expressed in the one-particle energy eigenbasis, decohere, so that only the diagonal entries, i.e. the occupation numbers, survive. In addition, the time evolution of the (retarded) Green's function also determines the spectral properties of the various one-particle quantum states.

    nucl-thhep-phquant-phPLB(2024)·9 citations
  3. 03

    Paring correlations within the micro-macroscopic approach for the level density

    A.G.Magner · A.I.Sanzhur · S.N.Fedotkin · A.I.Levon · U.V.Grygoriev · S.Shlomo

    Level density is calculated for the two-component close- and open-shell nuclei with a given energy , and neutron and proton numbers, taking into account pairing effects within the microscopic-macroscopic approach (MMA). These analytical calculations have been carried out by using the semiclassical statistical mean-field approximations beyond the saddle-point method of the Fermi gas model in a low excitation-energies range. The level density , obtained as function of the system entropy , depends essentially on the condensation energy through the excitation energy in super-fluid nuclei. The simplest super-fluid approach, based on the BCS theory, accounts for a smooth temperature dependence of the pairing gap due to particle number fluctuations. Taking into account the pairing effects in magic or semi-magic nuclei, excited below neutron resonances, one finds a notable pairing phase transition.Pairing correlations sometimes improve significantly the comparison with experimental data.

    nucl-thEPJA(2024)·3 citations
  4. 04

    and mesons in nuclear matter and nuclei

    J.J Cobos-Martinez🇲🇽 · Kazuo Tsushima🇧🇷

    We present updated and extended results for the - and -nucleus bound state energies, obtained by solving the Schrödinger and Klein-Gordon equations with complex optical potentials, for a wide range of nuclei. The and nuclear potentials are obtained in the local density approximation from the mass shift of these mesons in nuclear matter, which is calculated within the quark-meson coupling model. Our results show that the and mesons are expected to form mesic nuclei with all the nuclei considered. However, the signal for the formation of the - and -mesic nuclei may be difficult to identify experimentally due to possible large widths.

    nucl-thhep-phPRC(2024)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE