Nuclear Theory·nucl-th

Tuesday·April 2, 2024

15 papers—8 primary·7 cross-listed

01
[Submitted on 26 Mar 2024]
Multiscale physics of atomic nuclei from first principles
Z. H. Sun · A. Ekström · C. Forssén · G. Hagen · G. R. Jansen · T. Papenbrock
Atomic nuclei exhibit multiple energy scales ranging from hundreds of MeV in binding energies to fractions of an MeV for low-lying collective excitations. As the limits of nuclear binding is approached near the neutron- and proton driplines, traditional shell-structure starts to melt with an onset of deformation and an emergence of coexisting shapes. It is a long-standing challenge to describe this multiscale physics starting from nuclear forces with roots in quantum chromodynamics. Here we achieve this within a unified and non-perturbative framework that captures both short- and long-range correlations starting from modern nucleon-nucleon and three-nucleon forces from chiral effective field theory. The short-range correlations which accounts for the bulk of the binding energy is included within a symmetry-breaking framework, while long-range correlations (and fine details about the collective structure) are included via symmetry projection. Our calculations accurately reproduce available experimental data for low-lying collective states and the electromagnetic quadrupole transitions in $^{20 - 30}$ Ne. We also reveal coexisting spherical and deformed shapes in $^{30}$ Ne, which indicates the breakdown of the magic neutron number $N = 20$ as the key nucleus $^{28}$ O is approached, and we predict that the dripline nuclei $^{32, 34}$ Ne are strongly deformed. By developing reduced-order-models for symmetry-projected states, we perform a global sensitivity analysis and find that the subleading singlet S-wave contact and a pion-nucleon coupling strongly impact nuclear deformation in chiral effective-field-theory. The techniques developed in this work clarify how microscopic nuclear forces generate the multiscale physics of nuclei spanning collective phenomena as well as short-range correlations and allow to capture emergent and dynamical phenomena in finite fermion systems.
Comments:
This work significantly expands upon ideas from arXiv:2305.06955. While it includes some overlap in text to maintain context, substantial new content, methodology, and analysis are presented. 26 pages, 16 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2404.00058 [pdf]
PRX(2025)·71 citations
02
[Submitted on 27 Mar 2024]
Uncertainty Quantification of Collective Nuclear Observables From the Chiral Potential Parametrization
Kevin S. Becker · Kristina D. Launey · Andreas Ekström · Tomáš Dytrych · Daniel Langr · Grigor H. Sargsyan · Jerry P. Draayer
We perform an uncertainty estimate of quadrupole moments and B(E2) transition rates that inform nuclear collectivity. In particular, we study the low-lying states of 6Li and 12C using the ab initio symmetry-adapted no-core shell model. For a narrow standard deviation of approximately 1% on the low-energy constants which parametrize high-precision chiral potentials, we find output standard deviations in the collective observables ranging from approximately 3-6%. The results mark the first step towards a rigorous uncertainty quantification of collectivity in nuclei that aims to account for all sources of uncertainty in ab initio descriptions of challenging collective and clustering observables.
Comments:
12 pages, 10 figures, proceedings article for the International Workshop "Shapes and Dynamics of Atomic Nuclei: Contemporary Aspects" (SDANCA-23)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.00063 [pdf]
Phys.Scripta(2024)·3 citations
03
[Submitted on 30 Mar 2024]
Decoding rotating neutron stars: Role of the symmetry energy slope
Luiz L. Lopes🇧🇷
In December 2023, the Fermi LAT Catalog announced the discovery of 33 new millisecond pulsars. Motivated by that, in this work, I study how different values of the symmetry energy slope $(L)$ affect the properties of static and slowly rotating neutron stars. For fixed values of angular velocity, I study how the slope influences the increase of the maximum mass, the radii of the canonical 1.4 solar mass, its eccentricity, as well the same quantities for the 2.01 $M_{⊙}$ stars. I show that different slope values cause different variations not only the absolute quantities but also in relative ones. Indeed, different slope values predict different values for the eccentricity, which does not depend on the absolute value of the neutron stars' radii. Therefore, this quantity can be a powerful tool to constrain the symmetry energy slope.
Comments:
11 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2404.00223 [pdf]
ApJ(2024)·11 citations
04
[Submitted on 30 Mar 2024]
Theoretical investigation of heavy cluster decay from Z=118 and 120 isotopes: A search for an empirical formula in superheavy region
G. Saxena · Dashty T. Akrawy · Ali H. Ahmed · Mamta Aggarwal
Various decay modes in superheavy nuclei have been of significant interest among which cluster radioactivity has recently gained sizable attention. The {\alpha}-decay being a predominant decay mode in the superheavy region, the accurate determination of cluster decay half-lives is also crucial in this region as it has tremendous potential to be explored as one of the major decay channels. The usability of the Royer analytical formula [Nuclear Physics A 683 (2001) 182], which is based on the asymmetric fission model, has been investigated for the cluster and {\alpha} decay in superheavy region, by comparing it with several other (semi)empirical/analytical formulas. After fitting the formula on around 100 cluster-decay data and around 423 {\alpha}-decay data, the refitted Royer formula (RRF) is found to be very robust which is able to estimate the cluster decay and {\alpha}-decay half-lives with good accuracy. In fact, a comparison of the half-lives of both the decay modes using the same formula points towards a substantial chance of heavy cluster (Kr and Sr) decay from various isotopes of Z=118 and 120. Hence, the formula proposed in this study works fairly well for the estimation of cluster decay half-lives in superheavy regions where most empirical formulas fail to match with the half-lives from the various established theories.
Comments:
17 pages, 4 figures, Accepted in Nuclear Physics A
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.00305 [pdf]
NPA(2024)·2 citations
05
[Submitted on 30 Mar 2024]
Thermal production of charm quarks in relativistic heavy-ion collisions
Taesoo Song🇩🇪 · Ilia Grishmanovskii🇩🇪 · Olga Soloveva🇩🇪 · Elena Bratkovskaya🇩🇪
We investigate the thermal production of charm quarks in the strongly interacting quark-gluon plasma (sQGP) created in heavy-ion collisions at relativistic energies. Our study is based on the off-shell parton-hadron-string dynamics (PHSD) transport approach describing the full time evolution of heavy-ion collisions on a microscopic basis with hadronic and partonic degrees of freedom. The sQGP is realized within the effective dynamical quasi-particle model (DQPM) which is adjusted to reproduce the lattice QCD results for the thermodynamic observables of the sQGP. Relying on the fact that the DQPM successfully describes the spatial diffusion coefficients $D_{s}$ from the lQCD, which control the interaction of charm quarks with thermal partons (expressed in terms of strongly interacting off-shell quasiparticles), we evaluate the production of charm quark pairs through the rotation of Feynman diagrams such that the incoming charm quark and outgoing light parton in elastic scattering diagrams are exchanged. The charm quark annihilation is realized by detailed balance. We find that the number of produced thermal charm quark pairs strongly depends on the charm quark mass in the QGP. While for the heavy charm quarks of mass $m_{c} = 1.8$ GeV it is subdominant compared to the primary charm production by binary nucleon-nucleon collisions at RHIC and LHC energies, the numbers of primary and thermal charm quarks become comparable for a smaller (bare) $m_{c} = 1.2$ GeV. Compared with the experimental data on the $R_{AA}$ of $D$ -mesons in heavy-ion collisions at RHIC and LHC energies, it is more favorable for charm quarks in the QGP to gain additional mass due to thermal effects rather than to have a low bare mass.
Comments:
10 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2404.00425 [pdf]
PRC(2024)·14 citations
06
[Submitted on 30 Mar 2024]
Revisiting the 3{\alpha} reaction rates in helium burning stars
Theodoros Depastas · Shuting Sun · Hongbin Heb · Hua Zheng · Aldo Bonasera
Helium burning is one of the most fundamental steps of stellar nucleosynthesis, as it describes the formation of life-determining element of carbon, while it plays a key role in the evolution of Red Giant, accreting White Dwarfs and Neutron Stars. In this work we develop a generalized statistical theory for the 3{\alpha} reaction, which is based on the use of the Imaginary Time Method, along with the semi-classical Hybrid {\alpha}-Clustering (H{\alpha}C) and Neck Model (NM) frameworks. The results compared to the methodology and data of the NACRE collaboration, following in several orders of magnitude discrepancies, especially at low temperatures. This may be crucial for the early dynamics of helium burning stars.
Comments:
5 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2404.00454 [pdf]
PLB(2025)·7 citations
07
[Submitted on 30 Mar 2024]
Coordinate versus momentum cuts and effects of collective flow on critical fluctuations
Volodymyr A. Kuznietsov🇺🇸 · Mark I. Gorenstein🇺🇦 · Volker Koch🇺🇸 · Volodymyr Vovchenko🇺🇸
We analyze particle number fluctuations in the crossover region near the critical endpoint of a first-order phase transition by utilizing molecular dynamics simulations of the classical Lennard-Jones fluid. We extend our previous study [V.A. Kuznietsov et al., Phys. Rev. C 105, 044903 (2022)] by incorporating longitudinal collective flow. The scaled variance of particle number distribution inside different coordinate and momentum space acceptances is computed through ensemble averaging and found to agree with earlier results obtained using time averaging, validating the ergodic hypothesis for fluctuation observables. Presence of a sizable collective flow is found to be essential for observing large fluctuations from the critical point in momentum space acceptances. We discuss our findings in the context of heavy-ion collisions.
Comments:
13 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2404.00476 [pdf]
PRC(2024)·10 citations
08
[Submitted on 1 Apr 2024]
Farside-dominant quasinuclear rainbow in refractive $α$ + $α$ scattering
S. Ohkubo
$α$ + $α$ scattering has a long history since the first experiment by Rutherford and Chadwick in 1927 and has been studied thoroughly experimentally and theoretically. However, $α$ + $α$ scattering has never been paid attention from the viewpoint of refractive scattering. I have successfully analyzed the experimental angular distributions in $α$ + $α$ scattering systematically over a wide range of incident energies $E_{L}$ =53.4 - 280 MeV using a phenomenological optical model with a deep real potential. The existence of a farside-dominant quasinuclear rainbow with no well-defined rainbow angle and no supernumerary bow in the lit side followed by the shadow, which is not a genuine rainbow but a refractive scattering from a marginally small droplet at high energies, is found for the first time in $α$ + $α$ scattering. The refraction due to the deep potentials with an attractive core at short distances are discussed from the viewpoint of the Luneburg. The deep vs shallow problem of the potential and the nuclear rainbow scattering in inelastic channels are also discussed.
Comments:
8 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2404.00920 [pdf]
PRC(2024)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE