Hartree-Fock emulators for nuclei: Application to charge radii of ${}^{48,52}$Ca

Abstract

Understanding the emergence of complex structures of nuclei from chiral effective field theory (EFT) is a central challenge. The large number of low-energy couplings (LECs) in the EFT expansion and the significant cost of $\text{ab initio}$ many-body calculations render large-scale sensitivity studies of many-body observables computationally prohibitive, necessitating the use of emulators as low-cost surrogates. In this work, we study a Hartree-Fock emulator based on eigenvector continuation to investigate trends in nuclear charge radii of neutron-rich calcium isotopes. We systematically vary the five LECs entering the leading three-nucleon (3N) interactions, and demonstrate the precision of the emulator through cross-validation over a wide parameter space. Our findings indicate that large charge radius increase from ${}^{48}$Ca to ${}^{52}$Ca is likely not explained by variations of the leading 3N couplings. This suggests that other effects, such as sensitivities to chiral two-nucleon interactions or neglected many-body effects, e.g., associated with nuclear collectivity, play an important role.

13 pages, 12 figures

References in corpus (22)

• Chiral effective field theory and nuclear forces
• Improved nuclear matter calculations from chiral low-momentum interactions
• A Guided Tour of Ab Initio Nuclear Many-Body Theory
• Ab initio predictions link the neutron skin of ${}^{208}$Pb to nuclear forces
• In-Medium Similarity Renormalization Group for Nuclei
• Global sensitivity analysis of bulk properties of an atomic nucleus
• The effect of spin-orbit nuclear charge density corrections due to the anomalous magnetic moment on halonuclei
• In-medium similarity renormalization group with three-body operators
• What is ab initio in nuclear theory?
• Efficient emulators for scattering using eigenvector continuation
• \texttt{NuHamil}: A numerical code to generate nuclear two- and three-body matrix elements from chiral effective field theory
• Eigenvector Continuation and Projection-Based Emulators
• Fast emulation of quantum three-body scattering
• Fast & rigorous predictions for $A=6$ nuclei with Bayesian posterior sampling
• Multiscale physics of atomic nuclei from first principles
• Improved structure of calcium isotopes from ab initio calculations
• Excited states from eigenvector continuation: the anharmonic oscillator
• Emulators for scarce and noisy data: application to auxiliary field diffusion Monte Carlo for the deuteron
• Emulators for Scarce and Noisy Data: Application to Auxiliary-Field Diffusion Monte Carlo for Neutron Matter
• Inferring three-nucleon couplings from multi-messenger neutron-star observations
• Global Framework for Emulation of Nuclear Calculations
• An Efficient Learning Method to Connect Observables