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Nuclear Theory·nucl-th

Monday·August 26, 2024

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    Refining the isovector component of the Woods-Saxon potential

    L. Xayavong🇰🇷 · Y. Lim🇰🇷 · N. A. Smirnova🇫🇷 · G. Nam🇰🇷

    We investigate the isovector component in the phenomenological mean field model of nuclei. Lane's isospin dependence, initially proposed for the nuclear optical potential, is reexamined within the context of bound states using the Woods-Saxon potential. We demonstrate that the original parametrization can be reexpressed in terms of parameters associated with the compound nucleus, enhancing its suitability for bound states. Comparisons with the conventional symmetry term are performed to assess how well each approach fits experimental data on single-particle/hole energies and reproduces charge-radius systematics. Our results indicate that Lane's formula provides better accuracy compared with the traditional approach to the nuclear potential. Additionally, we find that the isovector component of the nuclear potential favors a surface-peaked form factor, especially one described by the first derivative of the Fermi like function divided by the radial coordinate. This consideration is crucial for open-shell nuclei where Woods-Saxon eigenfunctions serve as a realistic basis for other many-body methods. Our findings also enable discrimination among various shell-model calculations of the isospin-symmetry breaking correction to superallowed nuclear decays [I.~S. Towner and J.~C. Hardy, Phys. Rev. C {\bf 77}, 025501 (2008)]. This disparity currently constitutes the main source of theoretical uncertainty in subsequent tests of the standard model.

    nucl-thnucl-ex0 citations
  2. 02

    Quarkyonic equation of state with a momentum dependent interaction and neutron star structure

    K. Folias🇬🇷 · Ch.C. Moustakidis🇬🇷

    The structure and basic properties of dense nuclear matter still remain one of the open problems of Physics. In particular, the composition of the matter that composes neutron stars is under theoretical and experimental investigation. Among the theories that have been proposed, apart from the classical one where the composition is dominated by hadrons, the existence or coexistence of free quark matter is a dominant guess. An approach towards this solution is the phenomenological view according to which the existence of quarkyonic matter plays a dominant role in the construction of the equation of state (EOS). According to it the structure of the EOS is based on the existence of the quarkyonic particle which is a hybrid state of a particle that combines properties of hadronic and quark matter with a corresponding representation in momentum space. In this paper we propose a phenomenological model for quarkyonic matter, borrowed from corresponding applications in hadronic models, where the interaction in the quarkyonic matter depends not only on the position but also on the momentum of the quarkyonic particles. This consideration, as we demonstrate, can have a remarkable consequence on the shape of the EOS and thus on the properties of neutron stars, offering a sufficiently flexible model. Comparison with recent observational data can place constraints on the parameterization of the particular model and help improve its reliability.

    nucl-thastro-ph.HEhep-phNPA(2025)·7 citations
  3. 03

    Statistical uncertainty quantification for multireference covariant density functional theory

    X. Zhang🇨🇳 · C. C. Wang🇨🇳 · C. R. Ding🇨🇳 · J. M. Yao🇨🇳

    We present a theoretical framework to quantify statistical uncertainties in covariant density functional theory (CDFT) for both nuclear matter and finite nuclei, based on a relativistic point-coupling energy density functional (EDF). By sampling approximately one million parameter sets, with nine parameters varied around their values in the PC-PK1 functional, we construct a probability density function for nuclear matter properties. Incorporating empirical values of nuclear matter at saturation density and those of predictions from chiral nuclear forces, and measured values of finite nuclei, we infer posterior distributions for the model parameters within a Bayesian framework. These posterior distributions are then propagated to the low-lying states of finite nuclei using the newly developed subspace-projected (SP)-CDFT approach, in which the wave functions of target EDF parameter sets are expanded in a subspace spanned by low-lying states obtained from a set of training parameterizations. We find that the observables of low-lying states in deformed nuclei Nd and Sm are well reproduced once statistical uncertainties are taken into account. In contrast, those of near spherical nuclei Xe and Ba remain difficult to describe within the present framework, a limitation that is expected to be alleviated by extending the model space to include quasiparticle excitations.

    nucl-thnucl-exChinese Physics C, 2026·8 citations
  4. 04

    Spatial imaging of polarized deuterons at the Electron-Ion Collider

    Heikki Mäntysaari🇫🇮 · Farid Salazar🇺🇸 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇺🇸

    We study diffractive vector meson production at small- in the collision of electrons and polarized deuterons . We consider the polarization dependence of the nuclear wave function of the deuteron, which results in an azimuthal angular dependence of the produced vector meson when the deuteron is transversely polarized. The Fourier coefficients extracted from the azimuthal angular dependence of the vector meson differential cross-section exhibit notable differences between longitudinally and transversely polarized deuterons. The angular dependence of the extracted effective deuteron radius provides direct insight into the structure of the polarized deuteron wave function. Furthermore, we observe slightly increased gluon saturation effects when the deuteron is longitudinally polarized compared to the transversely polarized case. The small- observables studied in this work will be accessible at the future Electron-Ion Collider.

    nucl-thhep-phnucl-exPLB(2024)·8 citations
  5. 05

    Variational inference of effective range parameters for He-He scattering

    Andrius Burnelis · Vojta Kejzlar · Daniel R. Phillips

    We use two different methods, Monte Carlo sampling and variational inference (VI), to perform a Bayesian calibration of the effective-range parameters in He-He elastic scattering. The parameters are calibrated to data from a recent set of He-He elastic scattering differential cross section measurements. Analysis of these data for MeV yields a unimodal posterior for which both methods obtain the same structure. However, the effective-range expansion amplitude does not account for the state of Be so, even after calibration, the description of data at the upper end of this energy range is poor. The data up to MeV can be well described, but calibration to this lower-energy subset of the data yields a bimodal posterior. After adapting VI to treat such a multi-modal posterior we find good agreement between the VI results and those obtained with parallel-tempered Monte Carlo sampling.

    nucl-thstat.APJ.Phys.G(2025)·2 citations
  6. 06

    Vertex correction to nuclear matrix elements of double- decays

    Jun Terasaki🇨🇿

    The predicted neutrinoless double- () decay is the crucial phenomenon to prove the existence of the Majorana neutrino, which gives a foundation to leptogenesis to explain the matter prevalence of the universe. The nuclear matrix element (NME) of decay is an important theoretical quantity to determine the effective neutrino mass and help the detector design for the next generation of the decay search. Reliable calculation of this NME is a long-standing problem because of the diversity of the predicted values of the NME. The main reason for this difficulty is that the effective strength of the Gamow-Teller transition operator for this decay is unknown. I will show the lowest-order vertex corrections for the and the NME of Xe in the framework of the hybrid application of the quantum field theory to the leptons and the Rayleigh-Schrödinger perturbation to the nucleus. The unperturbed nuclear states are obtained by the quasiparticle random-phase approximation. These corrections reduce the NME by 30%. The effective referring to this reduced NME is also obtained, and it is shown for the first time that the effective for the NME is not quite different from that for the NME; the difference is only 10%. This indicates the possibility that the phenomenological effective to reproduce the experimental half-life of the decay can be approximately used for the calculation of the NME.

    nucl-thhep-phnucl-exPoS(2025)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE