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We utilize the machine learning to extrapolate to the infinite model space the no-core shell model (NCSM) results for the energies and rms radii of the 6He ground state and 6Li lowest states. The extrapolated energies and rms radii converge…

Nuclear Theory · Physics 2025-04-10 R. E. Sharypov , A. I. Mazur , A. M. Shirokov

Calculations of nuclei are often carried out in finite model spaces. Thus, finite-size corrections enter, and it is necessary to extrapolate the computed observables to infinite model spaces. In this work, we employ extrapolation methods…

Nuclear Theory · Physics 2019-11-25 W. G. Jiang , G. Hagen , T. Papenbrock

Ab initio approaches in nuclear theory, such as the no-core shell model (NCSM), have been developed for approximately solving finite nuclei with realistic strong interactions. The NCSM and other approaches require an extrapolation of the…

We present a comparison of model-space extrapolation methods for No-Core Shell Model calculations of ground-state energies and root-mean-square radii in Li isotopes. In particular, we benchmark the latest machine learning tools against…

The prediction of nuclear observables beyond the finite model spaces that are accessible through modern ab initio methods, such as the no-core shell model, pose a challenging task in nuclear structure theory. It requires reliable tools for…

Nuclear Theory · Physics 2023-03-15 Marco Knöll , Tobias Wolfgruber , Marc L. Agel , Cedric Wenz , Robert Roth

For light nuclei, ab initio many-body methods such as the no-core shell model are the tools of choice for predictive, high-precision nuclear structure calculations. The applicability and the level of precision of these methods, however, is…

Nuclear Theory · Physics 2024-07-29 Tobias Wolfgruber , Marco Knöll , Robert Roth

A new two-dimensional procedure for extrapolation of the values of matter, neutron, and proton radii obtained in no-core shell model (NCSM) calculations to infinite size of its basis is proposed. A relationship between the radii is used as…

Nuclear Theory · Physics 2022-10-05 D. M. Rodkin , Yu. M. Tchuvil'sky

We report \textit{ab initio} no-core shell model (NCSM) study of $^{18-24}$Ne isotopes for energy spectra, electromagnetic properties, and point-proton radii using three realistic $NN$ interactions. We have used inside nonlocal outside…

Nuclear Theory · Physics 2023-02-08 Chandan Sarma , Praveen C. Srivastava

We precisely determine the infrared (IR) length scale of the no-core shell model (NCSM). In the NCSM, the $A$-body Hilbert space is truncated by the total energy, and the IR length can be determined by equating the intrinsic kinetic energy…

Nuclear Theory · Physics 2015-06-24 K. A. Wendt , C. Forssén , T. Papenbrock , D. Sääf

We report $J^\pi = 0^+$ ground-state energies and point-proton radii of $^4$He, $^8$Be, $^{12}$C, $^{16}$O and $^{20}$Ne nuclei calculated by the $ab$ $initio$ no-core Monte Carlo shell model with the JISP16 and Daejeon16 nonlocal $NN$…

Nuclear Theory · Physics 2021-11-29 T. Abe , P. Maris , T. Otsuka , N. Shimizu , Y. Utsuno , J. P. Vary

We report on Li-6 calculations performed with the IT-NCSM and compare them to full NCSM calculations. We employ the Entem and Machleidt chiral two-body N3LO interaction (regulated at 500 MeV/c), which has been modified to a phase-shift…

Nuclear Theory · Physics 2013-04-10 M. K. G. Kruse , E. D. Jurgenson , P. Navrátil , B. R. Barrett , W. E. Ormand

We employ a feed-forward artificial neural network to extrapolate at large model spaces the results of {\it ab-initio} hypernuclear No-Core Shell Model calculations for the $\Lambda$ separation energy $B_\Lambda$ of the lightest…

Nuclear Theory · Physics 2023-03-22 Isaac Vidana

We introduce a hybrid many-body approach that combines the flexibility of the No-Core Shell Model (NCSM) with the efficiency of Multi-Configurational Perturbation Theory (MCPT) to compute ground- and excited-state energies in arbitrary…

Nuclear Theory · Physics 2018-10-24 Alexander Tichai , Eskendr Gebrerufael , Klaus Vobig , Robert Roth

Accurately determining the size of the atomic nucleus with realistic nuclear forces is a long outstanding issue of nuclear physics. The no-core shell model (NCSM), one of the powerful ab initio methods for nuclear structure, can achieve…

Nuclear Theory · Physics 2025-02-07 Xiang-Xiang Sun , Hoai Le , Ulf-G. Meißner , Andreas Nogga

The spectrum, partial and total decay widths of the states of the exotic 10Li nucleus are studied in an ab initio approach. The spectrum is calculated using No-Core Shell Model and corresponding extrapolation procedure. The calculations use…

Nuclear Theory · Physics 2022-04-19 Dmitry Rodkin , Yury Tchuvil'sky

A realistic description of halo nuclei, characterized by low-lying breakup thresholds, requires a proper treatment of continuum effects. We have developed an ab initio approach, the no-core shell model with continuum (NCSMC), capable of…

Nuclear Theory · Physics 2026-05-26 Petr Navratil , Sofia Quaglioni , Guillaume Hupin , Michael Gennari , Kostas Kravvaris

We present an overview of recent results and developments of the no-core shell model (NCSM), an ab initio approach to the nuclear many-body problem for light nuclei. In this approach, we start from realistic two-nucleon or two- plus…

Nuclear Theory · Physics 2009-06-19 Petr Navratil , Sofia Quaglioni , Ionel Stetcu , Bruce R. Barrett

The energy levels of light hypernuclei are experimentally accessible observables that contain valuable information about the interaction between hyperons and nucleons. In this work we study strangeness $S = -1$ systems $^{3,4}_\Lambda$H and…

Nuclear Theory · Physics 2022-11-23 D. Gazda , T. Yadanar Htun , C. Forssén

No-core shell model (NCSM) calculations using ab initio effective interactions are very successful in reproducing experimental nuclear spectra. The main theoretical approach is the use of effective operators, which include correlations left…

Nuclear Theory · Physics 2007-05-23 Bruce R. Barrett , Ionel Stetcu , Petr Navratil , James P. Vary

We perform the ab initio no-core shell model (NCSM) calculation to investigate the bound state problem of the three-body $\Lambda nn$ system in chiral next-to-next-to-leading-order NN and chiral leading-order YN interactions. The…

Nuclear Theory · Physics 2022-11-04 Thiri Yadanar Htun , Yupeng Yan
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