PaperPanorama
FAQ

Nuclear Theory·nucl-th

Friday·August 30, 2024

10 papers—7 primary·3 cross-listed

All10Primary7Cross-lists3
  1. 01

    [Submitted on 28 Aug 2024]

    Neutron skins: A perspective from dispersive optical models

    M. C. Atkinson · W. H. Dickhoff

    An overview is presented of neutron skin predictions obtained using an empirical nonlocal dispersive optical model (DOM). The DOM links both scattering and bound-state experimental data through a subtracted dispersion relation which allows for fully-consistent, data-informed predictions for nuclei where such data exists. Large skins were predicted for both Ca ( fm in 2017) and Pb ( fm in 2020). While the DOM prediction in Pb is within 1 of the subsequent PREX-2 measurement, the DOM prediction in Ca is over 2 larger than the thin neutron skin resulting from CREX. From the moment it was revealed, the thin skin in Ca has puzzled the nuclear-physics community as no adequate theories simultaneously predict both a large skin in Pb and a small skin in Ca. The DOM is unique in its ability to treat both structure and reaction data on the same footing, providing a unique perspective on this puzzle. It appears vital that more neutron data be measured in both the scattering and bound-state domain for Ca to clarify the situation.

    Comments:
    21 pages, 9 figures, 2 tables. arXiv admin note: substantial text overlap with arXiv:1911.09020
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2408.16097 [pdf]
    0 citations
  2. 02

    [Submitted on 29 Aug 2024]

    Gamow shell model description of neutron-rich He hyper-isotopes

    Xin Li · N. Michel · J. G. Li · Xian-Rong Zhou

    The Gamow shell model (GSM) framework has been extended to the study of weakly bound hypernuclei. As a first application, the neutron-rich He hyper-isotope chains, from 6{\Lambda}He to 9{\Lambda}He have been investigated to accurately account for the loosely bound or neutron-unbound character of hypernuclear many-body states. The energy spectra calculated with a phenomenological Hamiltonian show good agreement with experimental data. In particular, neutron-emitting resonant states are predicted for the neutron-rich nuclei 5-7He and the hypernucleus 6{\Lambda}He. Furthermore, one-neutron densities exhibit the long-range character of weakly bound and resonant states. This study demonstrates that GSM is a practical tool for describing the complex structure of hypernuclei, especially for those close to drip lines.

    Comments:
    3 pages
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2408.16223 [pdf]
    PLB(2025)·7 citations
  3. 03

    [Submitted on 29 Aug 2024]

    Role of nuclear deformation and orientation about symmetry axis of target nucleus on heavy-ion fusion dynamics

    Shilpa Rana · M. Bhuyan · Raj Kumar · B. V. Carlson

    Nuclear shape and orientation degrees of freedom are incorporated into the calculation of the double-folding nuclear potential within the relativistic mean-field (RMF) formalism. The quadrupole deformations (), nuclear densities and the effective nucleon-nucleon (NN) interaction potential are obtained using the RMF approach for the Hybrid, NL3 and NL3 parameterizations. The calculated quadrupole deformations are included in the target densities through the nuclear radius. The deformation and orientation-dependent microscopic nuclear potentials are further employed to obtain fusion barrier characteristics and cross-sections for 12 even-even heavy-ion reactions with doubly magic spherical O and Ca as projectiles along with deformed targets from different mass regions. The results obtained for the relativistic R3Y NN potential are compared with those of the Reid version of the non-relativistic M3Y NN potential as well as with the available experimental data. A decrease in the barrier height and increase in the cross-section is observed upon the inclusion of target quadrupole deformations in the nuclear density distributions at the target orientation angles, for the R3Y NN potential and at for the M3Y NN potential. On comparing the -integrated cross-section calculated using M3Y and R3Y NN potentials with spherical and deformed densities, one observes that the deformed densities and the relativistic R3Y NN potential obtained for the Hybrid parameter set provide better agreement with the available experimental data for all the considered reactions. Moreover, the modifications in the characteristics of the fusion barrier and hence in the cross-section with the inclusion of nuclear shape degrees of freedom and orientations are found to become more prominent in reactions forming heavier compound nuclei.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2408.16436 [pdf]
    PRC(2024)·4 citations
  4. 04

    [Submitted on 29 Aug 2024]

    Persistence of the N = 50 shell closure over the isotopic chains of Sc, Ti, V and Cr nuclei using relativistic energy density functional

    Praveen K. Yadav · Raj Kumar · M. Bhuyan

    The analytical expression of the density-dependent binding energy per nucleon for the relativistic mean field (RMF), also known as the relativistic energy density functional (Relativistic-EDF), is used to obtain the isospin-dependent symmetry energy and its components for the isotopic chain of Sc, Ti, V, and Cr nuclei. The procedure of the coherent density fluctuation model is employed to formulate the Relativistic-EDF and Brueckner energy density functional (Brueckner-EDF) at local density. A few signatures of shell and/or sub-shell closure are observed in the symmetry energy and its components, i.e., surface and volume symmetry energy, far from the beta-stable region for odd-A Sc and V, and even-even Ti and Cr nuclei with non-linear NL3 and G3 parameter sets. A comparison is made with the results obtained from Relativistic-EDF and Brueckner-EDF with both NL3 and G3 for the considered isotopic chains. We find Relativistic-EDF outperforms the Brueckner-EDF in predicting the shell and/or sub-shell closure of neutron-rich isotopes at N = 50 for these atomic nuclei. Moreover, a relative comparison has been made for the results obtained with the non-linear NL3 and G3 parameter sets.

    Comments:
    18 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
    arXiv:
    2408.16588 [pdf]
    Mod.Phys.Lett.A(2023)·3 citations
  5. 05

    [Submitted on 29 Aug 2024]

    Distinguishing the sources of dielectron anisotropic flow at low beam energies

    Renan Hirayama🇩🇪 · Hannah Elfner🇩🇪

    We present calculations of dielectron anisotropic flow in heavy-ion collisions at HADES beam energies from a hadronic transport approach. The ongoing experimental analysis employs the traditional reaction plane method to evaluate the flow coefficients and claims to see isotropic radiation from the thermal quark-gluon plasma. We show in this work, that in the region above the pion mass, the dilepton flow measurement might suffer from cancellation effects that mask the complicated underlying dynamics. Contributions from different baryonic and mesonic resonances show collective behaviour with different signs and lead to an overall vanishing elliptic flow. To differentiate the different contributions, we propose to employ the scalar product method, which exploits the previously measured hadronic flow to create different reference planes. As a proof of concept, we calculate the of dielectrons for Ag+Ag collisions at with both methods and investigate the contribution of each source, concluding that the scalar product method provides the proton and pion tagged flow coefficients as two distinct measurements, disentangling the various dilepton sources.

    Comments:
    10 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2408.16603 [pdf]
    PRC(2024)·7 citations
  6. 06

    [Submitted on 29 Aug 2024]

    Bounds on the minimum sound speed above neutron star densities

    Dake Zhou🇺🇸

    We show that the existence of massive neutron stars and asymptotic freedom of QCD place robust upper bounds on the lowest sound speed of the ultra-dense matter unattainable in neutron stars. Centered on worst-case scenarios, our limits are the most conservative among physical equations of state in the density range . Discovery of neutron stars, in combination with current multimessenger astrophysical constraints on the equation of state, would strongly support first-order phase transitions at high baryon densities.

    Comments:
    v2: broadened low-density uncertainties and updated refs
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
    arXiv:
    2408.16738 [pdf]
    1 citation
  7. 07

    [Submitted on 29 Aug 2024]

    The X17 boson and the d(p,e+ e-)3He and d(n,e+ e-)3H processes: a theoretical analysis

    M. Viviani🇮🇹 · E. Filandri🇮🇹 · L. Girlanda🇮🇹 · C. Gustavino🇮🇹 · A. Kievsky🇮🇹 · L.E. Marcucci🇮🇹

    The present work deals with the e+ e- pair production in the d(p,e+e-)3He and d(n,e+ e-)3H processes, in order to evidentiate possible effects due to the exchange of a hypothetical low-mass boson, the so-called X17. These processes are studied for energies of the incident beams in the range 18-30 MeV, in order to have a sufficient energy to produce such a boson, whose mass is estimated to be around 17 MeV. We first analyze them as a purely electromagnetic processes, in the context of a state-of-the-art approach to nuclear strong-interaction dynamics and nuclear electromagnetic currents, derived from chiral effective field theory chiEFT. Next, we examine how the exchange of a hypothetical low-mass boson would impact the cross sections for such processes. We consider several possibilities, that this boson is either a scalar, pseudoscalar, vector, or axial particle. The main aim of the study is to exploit the specular structure of the 3He and 3H nuclei to investigate the isospin dependency of the X17-nucleon interaction, as the alleged "proto-phobicity".

    Comments:
    19 pages, 15 figures, new version with more details, added two appendices. arXiv admin note: text overlap with arXiv:2104.07808
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2408.16744 [pdf]
    PRC(2025)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE