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Nuclear Theory·nucl-th

Wednesday·June 5, 2024

10 papers—3 primary·7 cross-listed

All10Primary3Cross-lists7
  1. 01

    A universal reduced basis for the calibration of covariant energy density functionals

    Amy L. Anderson · J. Piekarewicz

    The reduced basis method is used to construct a "universal" basis of Dirac orbitals that may be applicable throughout the nuclear chart to calibrate covariant energy density functionals. Relative to our earlier work using the non-relativistic Schrödinger equation, the Dirac equation adds an extra layer of complexity due to the existence of negative energy states. However, once this problem is mitigated, the resulting reduced basis is able to accurately and efficiently reproduce the high-fidelity model at a fraction of the computational cost. We are confident that the resulting reduced basis will serve as a foundational element in developing rapid and accurate emulators. In turn, these emulators will play a critical role in the Bayesian optimization of covariant energy density functionals.

    nucl-thnucl-exPRC(2024)·2 citations
  2. 02

    Towards accurate nuclear mass tables in covariant density functional theory

    A. Taninah · B. Osei · A.V.Afanasjev · U.Perera · S.Teeti

    The current investigation focuses on detailed analysis of the anchor based optimization approach (ABOA), its comparison with alternative global fitting protocols and on the global analysis of the truncation of basis effects in the calculation of binding energies. It is shown that ABOA provides a solution which is close to that obtained in alternative approaches but at small portion of their computational time. The application of softer correction function after few initial iterations of ABOA stabilizes and speeds up its convergence. For the first time, the numerical errors in the calculation of binding energies related to the truncation of bosonic and fermionic bases have been globally investigated with respect of asymptotic values corresponding to the infinite basis in the framework of covariant density functional theory (CDFT). These errors typically grow up with the increase of the mass and deformation of the nuclei. To reduce such errors in bosonic sector below 10 keV for almost all nuclei with proton number one should truncate the bosonic basis at instead of presently used . The reduction of the errors in binding energies due to the truncation of the fermionic basis in CDFT is significantly more numerically costly. For the first time it is shown that the pattern and the speed of the convergence of binding energies as a function of the size of fermionic basis given by depend on the type of covariant energy density functional. The use of explicit density dependence of the meson-nucleon coupling constants or point couplings slows down substantially the speed of convergence of binding energies as a function of . A new procedure for finding the asymptotic values of binding energies is suggested in the present paper: it allows better control of numerical errors.

    nucl-thPRC(2024)·10 citations
  3. 03

    Eikonal calculation of (p,3p) cross sections for neutron-rich nuclei

    M. Gómez-Ramos

    In this work, we present the first, to our knowledge, theoretical description of two-proton removal reactions with proton target for medium-mass nuclei at intermediate energies and present cross sections for the different bound states of the residual nucleus with two fewer protons. The description of the reaction assumes two sequential ``quasifree'' collisions between the target and removed protons and considers eikonal propagation in between. The formalism is applied to the reactions , and , finding reasonable agreement to experimental data for the C target and an overestimation of a factor for the more neutron-rich and Ca, which is similar to the results found in two-proton knockout experiments with Be and C targets.

    nucl-thPRC(2024)·1 citation

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first authorsco-authorsvia INSPIRE