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Nuclear Theory·nucl-th

Friday·February 7, 2025

17 papers—4 primary·13 cross-listed

All17Primary4Cross-lists13
  1. 01

    Emulators for Scarce and Noisy Data: Application to Auxiliary-Field Diffusion Monte Carlo for Neutron Matter

    Cassandra L. Armstrong · Pablo Giuliani · Kyle Godbey · Rahul Somasundaram · Ingo Tews

    Understanding the equation of state (EOS) of pure neutron matter is necessary for interpreting multimessenger observations of neutron stars. Reliable data analyses of these observations require well-quantified uncertainties for the EOS input, ideally propagating uncertainties from nuclear interactions directly to the EOS. This, however, requires calculations of the EOS for a prohibitively large number of nuclear Hamiltonians, solving the nuclear many-body problem for each one. Quantum Monte Carlo methods, such as auxiliary-field diffusion Monte Carlo (AFDMC), provide precise and accurate results for the neutron matter EOS, but they are very computationally expensive, making them unsuitable for the fast evaluations necessary for uncertainty propagation. Here, we employ parametric matrix models to develop fast emulators for AFDMC calculations of neutron matter and use them to directly propagate uncertainties of coupling constants in the Hamiltonian to the EOS. As these uncertainties include estimates of the effective field theory truncation uncertainty, this approach provides robust uncertainty estimates for use in astrophysical data analyses. This Letter will enable novel applications such as using astrophysical observations to put constraints on coupling constants for nuclear interactions.

    nucl-thPRL(2025)·27 citations
  2. 02

    Radii of light nuclei from the Jacobi No-Core Shell Model

    Xiang-Xiang Sun · Hoai Le · Ulf-G. Meißner · Andreas Nogga

    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 accurate energies of light nuclei. The extraction of converged radii is more difficult. In this work, we present a novel method to effectively extract the radius of light nuclei by restoring the long-range behavior of densities from NCSM calculations. The correct large distance asymptotic of two-body relative densities are deduced based on the NCSM densities in limited basis size. The resulting radii using the corrected densities show a nice convergence. The root-mean-square matter and charge radii of He and Li can be accurately obtained based on Jacobi-NCSM calculations with the high-precision chiral two-nucleon and three-nucleon forces combined with this new method. Our method can be straightforwardly extended to other ab initio calculations, potentially providing a better description of nuclear sizes with realistic nuclear forces.

    nucl-thPRC(2025)·6 citations
  3. 03

    Three-body structures of low-lying nuclear states of Li

    E. Garrido · A.S. Jensen

    The four nucleons in Li outside the -particle (He) can be divided into pairs of one neutron () and 3 nucleons in the triton (H), or 2 in the deuteron (H) and two neutrons in a dineutron (). The corresponding three-body structures, ++ or ++, are suggested to describe the bulk part of the low-energy (~MeV) states of Li. Several breakup thresholds influence the structures and possible decays. We calculate the three-body structures of the various states, where different clustering appear, e.g. Li*+, Li*, He*. The experimental Li spectrum can be reproduced with fine tuning by a three-body potential parameter. Three unobserved and an excited 2 states are found. All states appear as bound states or resonances. The lowest or highest energies have cluster structures, ++ or ++, respectively. We give calculated energy and width (if possible), geometry, and partial wave decomposition for all states.

    nucl-thnucl-exPRC(2025)·1 citation
  4. 04

    Exploring the limits of nucleonic metamodelling using different relativistic density functionals

    Prasanta Char · Chiranjib Mondal

    In this work, we explore two classes of density dependent relativistic mean-field models, their predictions of proton fractions at high densities and neutron star structure. We have used a metamodelling approach to these relativistic density functionals. We have generated a large ensemble of models with these classes and then applied constraints from theoretical and experimental nuclear physics and astrophysical observations. We find that both models produce similar equations of state and neutron star mass-radius sequences. But, their underlying compositions, denoted by the proton fraction in this case, are vastly different. This reinstates previous findings that information on composition gets masqueraded in -equilibrium. Additional observations of non-equilibrium phenomena are necessary to pin it down.

    nucl-thastro-ph.HEPRD(2025)·12 citations

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first authorsco-authorsvia INSPIRE