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Nuclear Theory·nucl-th

Friday·October 11, 2024

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    Isospin composition of fission barriers

    K. Godbey · C. Ross · A.S. Umar

    We employ a microscopic method to study how isospin affect the fission potential of Pu. Our approach uses constrained Hartree-Fock theory (CHF) which allows us to separately investigate the isoscalar and isovector properties of the nuclear energy density functional (EDF). By analyzing the isoscalar and isovector components of the EDF along the fission path we can assess the isovector contribution to fission barriers. We study this effect for the fully adiabatic path to scission. The isovector component of the fission potential is found to increase in magnitude as the nucleus evolves towards scission, exemplifying the importance of stringent constraints on the isovector sector of the nuclear EDF for reliable predictions of fission properties.

    nucl-thPRC(2024)·2 citations
  2. 02

    Re-investigation of neutron capture by 84Kr and 86Kr in the s-process nucleosynthesis

    Abdul Kabir · Zain Ul Abideen · Jameel-Un Nabi

    The thermonuclear reaction rates and Maxwellian averaged cross sections (MACS) for the 84Kr(n,{\gamma}) 85Kr and 86Kr(n,{\gamma}) 87Kr processes were examined using the statistical model code Talys v1.96. The effects of nuclear level densities (NLDs) on Maxwellian averaged cross sections and neutron capture rates are examined both quantitatively and qualitatively. The present Talys based MACS and radiative capture rates for 84Kr(n,{\gamma}) 85Kr and 86Kr(n,{\gamma}) 87Kr processes agree well with the earlier reported findings. The statistical models nuclear properties (level density and gamma ray strength) were fine tuned to reproduce the existing experimental nuclear data.

    nucl-thastro-ph.SRnucl-exBraz.J.Phys.(2024)·4 citations
  3. 03

    Investigation of Nuclear Structure and -decay Properties of As Isotopes

    Jameel-Un Nabi · Abdul Kabir · Wajeeha Khalid · Syeda Anmol Rida · Izzah Anwaar

    The nuclear ground state properties of 67 80As nuclei have been investigated within the framework of relativistic mean field (RMF) approach. The RMF model with density dependent (DDME2) interaction is utilized for the calculation of potential energy curves and the nuclear ground state deformation parameters of selected As isotopes. Later, the decay properties of As isotopes were studied using the proton neutron quasi particle random phase approximation pnQRPA model. These include Gamow Tellar (GT) strength distributions, log ft values, decay half lives, stellar plus minus decays and stellar electron positron capture rates. The values computed from RMF model were employed in the on QRPA model as an input parameter for the calculations of -decay properties for 67 80As. The calculated log ft values were in decent agreement with the measured data. The predicted -decay half lives matched the experimental values within a factor of 10. The stellar rates were compared with the shell model results. Only at high temperature and density values, the sum of plus and electron capture rates had a finite contribution. On the other hand, the sum of negative and positron capture rates were sizeable only at low density and high temperature values. For all such cases, the pn QRPA rates were found to be bigger than the shell model rates up to a factor of 33 or more. The findings reported in the current investigation could prove valuable for simulating the late stage stellar evolution of massive stars.

    nucl-thastro-ph.SRChin.J.Phys.(2024)·4 citations
  4. 04

    Relativistic spin hydrodynamics revisited with general rotation by entropy-current analysis

    Lixin Yang🇨🇳 · Li Yan🇨🇳

    We revisit the canonical formulation of spin hydrodynamics for Dirac fermions with a general thermal vorticity. The orders of the general thermal vorticity and the corresponding spin variables are considered independently from those of the conventional hydrodynamic variables and their perturbative gradients. Assuming a totally antisymmetric spin current of Dirac fermions, the entropy-current analysis with a general spin potential indicates that the constitutive relations of the stress-energy tensor have to involve spin variables, particularly those linked to boost symmetry, to adhere to the entropy principle. In the presence of the degree of freedom associated with boost symmetry, we choose the constitutive relations of the canonical formulation to be connected to those of the phenomenological formulation through pseudogauge transformation. Subsequently, a linear-mode analysis is conducted using the resulting spin hydrodynamic equations. It is observed that the spin and hydrodynamic modes in this canonical formulation display different characteristics compared to those in the phenomenological formulation up to the second order of gradient.

    nucl-thhep-phhep-th3 citations
  5. 05

    Frozen and -equilibrated and modes of cold neutron stars: nuclear metamodel predictions

    Gabriele Montefusco🇫🇷 · Marco Antonelli🇫🇷 · Francesca Gulminelli🇫🇷

    When the chemical re-equilibration timescale is sufficiently long, the normal and quasi-normal mode frequencies of neutron stars should be calculated in the idealized limit that the internal composition of each fluid element is fixed over the oscillation period. However, many studies rely on a barotropic equation of state, which implicitly overlooks potential out-of--equilibrium effects. To investigate possible biases arising from this assumption, we calculate the non-radial fundamental () and first pressure () modes for a wide range of neutron star structures, each governed by different nucleonic equations of state. This ensemble is generated using the metamodel technique, a phenomenological framework that incorporates constraints from experimental nuclear physics and chiral effective field theory. The metamodel also provides the internal composition of -equilibrated matter, allowing us to calculate oscillation modes beyond those supported by a purely barotropic fluid. Thus, we systematically assess the impact of assuming a barotropic equation of state across various equations of state and provide a distribution of expected and mode frequencies that may be detectable by next-generation gravitational wave interferometers.

    nucl-thastro-ph.HEAstron.Astrophys.(2025)·18 citations
  6. 06

    Towards a fluid-dynamic description of an entire heavy-ion collision: from the colliding nuclei to the quark-gluon plasma phase

    Andreas Kirchner🇩🇪 · Federica Capellino🇩🇪 · Eduardo Grossi🇮🇹 · Stefan Floerchinger🇩🇪

    The fluid-dynamical modeling of a nuclear collision at high energy usually starts shortly after the collision. A major source of uncertainty comes from the detailed modeling of the initial state. While the collision itself likely involves far-from-equilibrium dynamics, it is not excluded that a fluid theory of second order can reasonably well describe its soft features. Here we explore this possibility and discuss how the state before the collision can be described in that setup, what are the requirements from relativistic causality to the form of the equations of motion, how much entropy production can result from shear and bulk viscous dissipation during the initial longitudinal dynamics, and how one can thus obtain sensible initial conditions for the subsequent transverse expansion. While we do here only first steps, we outline a larger program. If the latter could be successfully completed it could lead to a dynamical description of heavy-ion collisions where the only uncertainty lies in the thermodynamic and transport properties of quantum chromodynamics.

    nucl-thPRC(2025)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE