Nuclear Theory·nucl-th

Wednesday·February 8, 2023

10 papers—5 primary·5 cross-listed

01
Skyrme-Hartree-Fock-Bogoliubov mass models on a 3D mesh. IIb. Fission properties of BSkG2
Wouter Ryssens🇧🇪 · Guillaume Scamps🇧🇪 · Stephane Goriely🇧🇪 · Michael Bender🇫🇷
Large-scale models of nuclear structure are currently the only way to provide consistent datasets for the many properties of thousands of exotic nuclei that are required by nucleosynthesis simulations. In [W.Ryssens et al., Eur. Phys. J. A 58, 246 (2022)], we recently presented the new BSkG2 model based on an energy density functional of the Skyrme type. Relying on a flexible three-dimensional coordinate representation of the nucleus, the model takes into account both triaxial deformation and time-reversal symmetry breaking. BSkG2 achieves a state-of-the-art global description of nuclear ground state (g.s.) properties and reproduces in particular the known masses with a root-mean-square (rms) deviation of 678 keV. Moving beyond g.s. properties, the model also reproduces all empirical values for the primary and secondary barriers as well as isomer excitation energies of actinide nuclei with rms deviations below 500 keV, i.e. with unprecedented accuracy. Here we discuss in detail the extension of our framework to the calculation of the fission barriers of 45 actinide nuclei, including odd-mass and odd-odd systems. We focus in particular on the impact of symmetry breaking which is key to the accuracy of the model: we allow systematically for axial, reflection and time-reversal symmetry breaking. The effect of the latter on the fission properties of odd-mass and odd-odd nuclei is small, but we find that allowing for shapes with triaxial or octupole deformation, as well as shapes with both, is crucial to achieving this accuracy. The numerical accuracy of our coordinate space approach, the variety of nuclear configurations explored and the simultaneous successful description of fission properties and known masses makes BSkG2 the tool of choice for the large-scale study of nuclear structure.
nucl-thEPJA(2023)·16 citations
02
The Los Alamos evaluation of $^{239}$ Pu neutron-induced reactions in the fast energy range
M. R. Mumpower · D. Neudecker · T. Kawano · M. Herman · N. Kleedtke · A. E. Lovell · I. Stetcu · P. Talou
A major revision of the evaluation of $^{239}$ Pu neutron-induced reaction cross sections is reported in the fast energy range. The evaluation starts at 2.5 keV incident neutron energy and has been extended up to 30 MeV. Several other notable changes are included in this evaluation since the release of ENDF/B-VIII.0 including the adoption of the Standards fission cross section, inclusion of new radiative capture data of Mosby et al., inclusion of the (n,2n) data of Meot et al., in addition to advances in the treatment of reaction modeling. In contrast to previous evaluation efforts, this evaluation is reproducible with detailed information stored chronologically utilizing a Git repository. The final evaluation results have been compiled into an ENDF-formatted file, which has been processed successfully through NJOY, checked for internal consistency, benchmarked versus older evaluations and validated against a suite of critical assemblies and pulsed-spheres.
nucl-thnucl-ex4 citations
03
Effect of the N3LO three-nucleon contact interaction on p-d scattering observables
L. Girlanda🇮🇹 · E. Filandri🇮🇹 · A. Kievsky🇮🇹 · L.E. Marcucci🇮🇹 · M. Viviani🇮🇹
A unitary transformation allows to remove redundant terms in the two-nucleon (2N) contact interaction at the fourth order (N3LO) in the low-energy expansion of Chiral Effective Field Theory. In so doing a three-nucleon (3N) interaction is generated. We express its short-range component in terms of five combinations of low-energy constants (LECs) parametrizing the N3LO 2N contact Lagrangian. Within a hybrid approach, in which this interaction is considered in conjunction with the phenomenological AV18 2N potential, we show that the involved LECs can be used to fit very accurate data on polarization observables of low-energy $p - d$ scattering, in particular the $A_{y}$ asymmetry. The resulting interaction is of the right order of magnitude for a N3LO contribution.
nucl-thPRC(2023)·20 citations
04
Universality Classes of Relativistic Fluid Dynamics: Foundations
Lorenzo Gavassino🇺🇸 · Marcelo M. Disconzi🇺🇸 · Jorge Noronha🇺🇸
A general organizing principle is proposed that can be used to derive the equations of motion describing the near-equilibrium dynamics of causal and thermodynamically stable relativistic systems. The latter are found to display some new type of universal behavior near equilibrium that allows them to be grouped into universality classes defined by their degrees of freedom, information content, and conservation laws. The universality classes expose a number of surprising equivalences between different theories, shedding new light on the near-equilibrium behavior of relativistic systems.
nucl-thgr-qchep-thPRL(2024)·42 citations
05
Predicting the neutrinoless double-beta decay matrix element of $^{136}$ Xe using a statistical approach
Mihai Horoi🇺🇸 · Andrei Neacsu🇷🇴 · Sabin Stoica🇷🇴
Calculation of the nuclear matrix elements (NMEs) for double-beta decay is of paramount importance for guiding experiments and for analyzing and interpreting the experimental data, especially for the search of the neutrinoless double beta decay mode ( $0 ν β β$ ). However, there are currently still large differences between the NME values calculated by different methods, hence a quantification of their uncertainties is very much required. In this paper we propose a statistical analysis of $0 ν β β$ NME for the $^{136} X e$ isotope, based on the interacting shell model, but using three independent effective Hamiltonians, emphasizing the range of the NMEs' most probable values and its correlations with observables that can be obtained from the existing nuclear data. Consequently, we propose a common probability distribution function for the $0 ν β β$ NME, which has a range of (1.55 - 2.65) at 90\% confidence level, with a mean value of 1.99 and a standard deviation of 0.37.
nucl-thhep-phPRC(2023)·24 citations
06
Carrollian Origins of Bjorken Flow
Arjun Bagchi🇮🇳 · Kedar S. Kolekar🇮🇳 · Ashish Shukla🇫🇷
Bjorken flow is among the simplest models of fluids moving near the speed of light ( $c$ ) while Carroll symmetry arises as a contraction of Poincaré group when $c \to 0$ . We show that Bjorken flow and its phenomenological approximations are completely captured by Carrollian fluids. Carrollian symmetries arise on generic null surfaces and a fluid moving at $c$ is restricted to such a surface, thereby naturally inheriting the symmetries. Carrollian hydrodynamics is thus not exotic, but rather ubiquitous, and provides a concrete framework for fluids moving at or near the speed of light.
↳ hep-thhep-phnucl-thPRL(2023)·68 citations
07
The Fractional Schrodinger Equation with the Generalized Woods-Saxon Potential
M. Abu-Shady · Etido P. Inyang
The bound state energy eigenvalues and the corresponding eigenfunctions of the generalized Woods-Saxon potential reported in [Phys. Rev. C 72, 027001 (2005)] is extended to the fractional forms using the generalized fractional derivative and the fractional Nikiforov-Uvarov (NU) technique. Analytical solutions of bound states of the Schrodinger equation for the present potential are obtained in the terms of fractional Jacobi polynomials. It is demonstrated that the classical results are a special case of the present results at Elfa=Beta=1 Therefore, the present results play important role in molecular chemistry and nuclear physics.
↳ quant-phnucl-thEast Eur.J.Phys.(2023)·6 citations
08
Enhancement of dilepton production rate and electric conductivity around QCD critical point
Toru Nishimura🇯🇵 · Masakiyo Kitazawa🇯🇵 · Teiji Kunihiro🇯🇵
We investigate whether the soft mode that becomes massless at the QCD critical point (CP) causes an enhancement of the dilepton production rate (DPR) and the electric conductivity around the CP through the modification of the photon self-energy. The modification is described by the so-called Aslamazov-Larkin, Maki-Thompson and density of states terms, which have been taken into account in our previous study on the DPR near the color-superconducting phase transition, with a replacement of the diquark modes with the soft mode of the QCD CP. We show that the coupling of photons with the soft modes brings about an enhancement of the DPR in the low invariant-mass region and the conductivity near the CP, which would be observable in the relativistic heavy-ion collisions.
↳ hep-phnucl-exnucl-thPTEP(2023)·13 citations
09
Thermal fading of the $1/ k^{4}$ -tail of the momentum distribution induced by the hole anomaly
Giulia De Rosi · Grigori E. Astrakharchik · Maxim Olshanii · Jordi Boronat
We study the thermal behavior of correlations in a one-dimensional Bose gas with tunable interaction strength, crossing from weakly-repulsive to Tonks-Girardeau regime. A reference temperature in this system is that of the hole anomaly, observed as a peak in the specific heat and a maximum in the chemical potential. We find that at large momenta $k$ and temperature above the anomaly threshold, the tail $C / k^{4}$ of the momentum distribution (proportional to the Tan contact $C$ ) is screened by the $1/∣ k ∣^{3}$ -term due to a dramatic thermal increase of the internal energy emerging from the thermal occupation of spectral excitation states. The same fading is consistently revealed in the behavior at short distances $x$ of the one-body density matrix (OBDM) where the $∣ x ∣^{3}$ -dependence disappears for temperatures above the anomaly. We obtain a new general analytic tail for the momentum distribution and a minimum $k$ fixing its validity range, both calculated with exact Bethe-Ansatz method and valid in all interaction and thermal regimes, crossing from the quantum to the classical gas limit. Our predictions are confirmed by comparison with ab-initio Path Integral Monte Carlo calculations for the momentum distribution and the OBDM exploring a wide range of interaction strength and temperature. Our results unveil a novel connection between excitations and correlations. We expect them to be of interest to any cold atomic, nuclear, solid-state, electronic and spin system exhibiting an anomaly or a thermal second-order phase transition.
↳ cond-mat.quant-gascond-mat.othernucl-thphysics.atom-ph+1PRA(2024)·7 citations
10
Nuclear shell-model simulation in digital quantum computers
A. Pérez-Obiol🇪🇸 · A. M. Romero🇪🇸 · J. Menéndez🇪🇸 · A. Rios🇪🇸 · A. García-Sáez🇪🇸 · B. Juliá-Díaz🇪🇸
The nuclear shell model is one of the prime many-body methods to study the structure of atomic nuclei, but it is hampered by an exponential scaling on the basis size as the number of particles increases. We present a shell-model quantum circuit design strategy to find nuclear ground states by exploiting an adaptive variational quantum eigensolver algorithm. Our circuit implementation is in excellent agreement with classical shell-model simulations for a dozen of light and medium-mass nuclei, including neon and calcium isotopes. We quantify the circuit depth, width and number of gates to encode realistic shell-model wavefunctions. Our strategy also addresses explicitly energy measurements and the required number of circuits to perform them. Our simulated circuits approach the benchmark results exponentially with a polynomial scaling in quantum resources for each nucleus. This work paves the way for quantum computing shell-model studies across the nuclear chart and our quantum resource quantification may be used in configuration-interaction calculations of other fermionic systems.
↳ quant-phnucl-thSci.Rep.(2023)·67 citations

Affiliations

first authorsco-authorsvia INSPIRE