Nuclear Theory·nucl-th

Wednesday·November 27, 2024

11 papers—7 primary·4 cross-listed

01
Universal Wong formula for capture cross sections from light to super-heavy systems
Ning Wang · Jinming Chen · Yicheng Wang · Hong Yao
A universal Wong formula is proposed with refined model parameters for a systematic description of the capture cross sections for heavy-ion fusion reactions from C+C to Ni+U, in which the barrier parameters and the barrier distribution are determined by the entrance-channel nucleus-nucleus potential based on the Skyrme energy density functional. With introducing a constraint to the width of the barrier distribution and a pocket-depth dependent barrier radius, the capture excitation functions for a number of fusion reactions involving different nuclear structure effects are remarkably well reproduced, particularly for the reactions between light nuclei and those forming super-heavy nuclei. The systematic decreasing behavior of the geometric radii with the depth of capture pocket due to the influence of deep inelastic scattering is clearly observed in the TDHF calculations for super-heavy systems. The predicted capture cross sections for $^{54}$ Cr + $^{238}$ U at above barrier energies are evidently smaller than the corresponding results of more asymmetric projectile-target combination $^{50}$ Ti + $^{242}$ Pu due to the shallower capture pocket in Cr+U.
nucl-thPRC(2025)·3 citations
02
Impact of Nuclear Deformation of Parent and Daughter Nuclei on One Proton Radioactivity Lifetimes
A. Jain · Pranali Parab · G. Saxena · Mamta Aggarwal
The influence of nuclear deformation on proton-decay half-lives has been systematically studied in microscopic theoretical frameworks for a wide range of nuclei with Z<82. Correlation between 1p-decay half-lives and the deformed nuclear shapes of both the parent and daughter nuclei has been investigated. Since the deformations of proton emitters and their residual nuclei impact the potential barrier and disintegration energy which are crucial for the accurate determination of half-lives, we incorporate the nuclear deformations of both the emitters and residues in a phenomenological manner and propose a new semi-empirical formula to estimate the 1p-decay half-lives. The robustness of this formula is demonstrated by the accurate predictions of the measured values while making it reliable for forecasting the properties of other potential proton emitters. The phenomenon of shape coexistence as observed in several proton emitters and their respective daughter nuclei, is particularly signicant in this context due to secondary minima in the potential energy surfaces of both the nuclei. Accounting for these factors signicantly affects the estimation of half-lives and branching ratios by introducing additional decay pathways and altering transition probabilities between different nuclear shapes.
nucl-thSci.Rep.(2024)·3 citations
03
$^{19}$ F $(p, γ)$ $^{20}$ Ne reaction rate and the puzzling calcium abundance in metal poor stars
G.X. Dong🇨🇳 · X.B. Wang🇨🇳 · N. Michel🇨🇳 · M. Płoszajczak🇫🇷
The $^{19}$ F $(p, γ)$ $^{20}$ Ne reaction is the only process to break out of the CNO cycle at temperature below 0.1 GK and may serve as the origin of calcium in first generation of stars after the Big Bang. In the recent measurement, the Jinping Underground Nuclear Experiment (JUNA) obtained the rate of $^{19}$ F $(p, γ)$ $^{20}$ Ne reaction, significantly larger than the previously recommended values. In this work, we perform the theoretical studies of the $^{19}$ F $(p, γ)$ $^{20}$ Ne reaction using the Gamow shell model in the coupled-channel representation (GSM-CC). At temperature around 0.1 GK, the predicted rate by GSM-CC is close to the rate found by JUNA. Thus, based on GSM-CC, the break-out reaction $^{19}$ F $(p, γ)$ $^{20}$ Ne from the CNO-cycle might win over its competing reaction $^{19}$ F $(p, α)$ $^{16}$ O, and produce enough calcium in the metal poor stars.
nucl-thPRC(2024)·4 citations
04
A solvable model for spin polarizations with flow-momentum correspondence
Anum Arslan🇨🇳 · Wen-Bo Dong🇨🇳 · Guo-Liang Ma🇨🇳 · Shi Pu🇨🇳 · Qun Wang🇨🇳
We present an analytically solvable model based on the blast-wave picture of heavy-ion collisions with flow-momentum correspondence. It can describe the key features of spin polarizations in heavy-ion collisions. With the analytical solution, we can clearly show that the spin polarization with respect to the reaction plane is governed by the directed flow, while the spin polarization along the beam direction is governed by the ellipticity in flow and in transverse emission area. There is a symmetry between the contribution from the vorticity and from the shear stress tensor due to the flow-momentum correspondence. The solution can be improved systematically by perturbation method.
nucl-thPRC(2025)·8 citations
05
Inner crust of neutron stars: Polymorphism and superconductivity in the liquid drop model
Dmitry Kobyakov · Xavier Viñas
Within the liquid drop model built up with the nuclear interaction parametrization Sk $χ$ 450, which is based on the chiral effective field theory, we calculate numerically the internal energy density for each of nuclear pasta phases and for the uniform nuclear matter. We provide quantitative arguments in favor of coexistence of various nuclear matter phases at a significant range of total pressure within the inner crust of neutron stars, a concept known as crystal polymorphism. Specifically, we find that differences of the internal energy per baryon for various phases are typically less than the thermal energy per a freedom degree at temperature about $1 0^{8}$ -- $1 0^{9}$ K, which sets the energetic scale for thermal fluctuations of state of Fermi liquid from the ground state. The nuclear energy contributions are described using the same parametrization Sk $χ$ 450 for the bulk, plain surface and curvature terms. We find that the introduction of the curvature correction changes the ground state in a relevant way. This may be understood as a consequence of the corresponding change in size of the nucleus, which significantly modifies the phase transition densities. Using the calculated structural parameters from liquid drop model, we explore the physical consequences of the expected Cooper pairing of protons in lasagna phase. In this case, we find a crossover between the discreet layered and the three-dimensional anisotropic regimes of superconductivity. Additionally, we study the magnetic stress in lasagna accounting for a rotational lag between superfluid neutrons and the crystal lattice, which is believed to develop naturally in pulsars and magnetars. Our results offer a preliminary insight into rich magnetic properties of the inner crust of neutron stars.
nucl-thastro-ph.HEastro-ph.SRhep-th+12 citations
06
Isomer triplets in odd-odd transitional rare earth nuclei: unique features, orbital systematics and characterization
N. Susshma · S. Deepa · K. Vijay Sai · R. Gowrishankar
The existence of low-lying long-lived isomers, predominantly in odd-odd nuclei of the light rare-earth mass region, is investigated through an extensive survey of available nuclear data. The characteristics of these isomeric states and their systematics has revealed intriguing and unusual properties, including the identification of isomer triplets, a phenomenon specific to odd-odd deformed nuclei close to the transition region. This exclusive feature was observed in the following odd-odd nuclei, namely, 152Pm, 152Eu, 154Tb, 156Tb, 156Ho, 158Ho, 160Ho, 162Lu and 166Lu. We present a detailed overview of these isomer triplets by exploring the systematics of single-quasiparticle proton and neutron orbitals near the Fermi surface relevant in this mass region, to elucidate the factors responsible for their formation. The low-lying level structures of 156Tb and 154Tb, were constructed using the well-tested Two Quasiparticle Rotor Model to resolve the ambiguities in the spin, parity, energy and orbital configuration of these isomeric states. These results were extended to study the systematics of low-lying isomer triplets in the other five light rare-earth nuclei of interest. Our review and analysis of 1qp proton and neutron orbital systematics in the neighboring odd-mass isotopes and isotones highlights the crucial role of high-spin intruder neutron orbital in the formation of these isomer triplets.
nucl-th0 citations
07
Lattice simulation of nucleon distribution and shell closure in the proton-rich nucleus $^{22}$ Si
Shuang Zhang · Serdar Elhatisari · Ulf-G. Meißner · Shihang Shen
The proton-rich nucleus $^{22}$ Si is studied using Nuclear Lattice Effective Field Theory with high-fidelity chiral forces. Our results indicate that $^{22}$ Si is more tightly bound than $^{20}$ Mg, thereby excluding the possibility of two-proton emission. The $Z = 14$ shell closure in $^{22}$ Si is supported by the evolution of the $2^{+}$ state in the neighboring nuclei. We then focus on the charge radius and spatial distribution information of $^{22}$ Si, considering the novel phenomena that may emerge due to the small two-proton separation energy and the shell closure. We present the distribution of the $14$ protons and $8$ neutrons obtained from our lattice simulation, revealing insights into the spatial arrangement of the nucleons. Moreover, the spatial localization of the outermost proton and neutron suggests that $^{22}$ Si is a doubly magic nucleus. Furthermore, we develop the pinhole method based on the harmonic oscillator basis, which gives insight into the nuclear structure in terms of the shell model picture from lattice simulations. Our calculated occupation numbers support that $Z = 14$ and $N = 8$ are the shell closures and show that the $π 1 s_{1/2}$ orbital component is minor in $^{22}$ Si.
nucl-thastro-ph.SRhep-latnucl-exPLB(2025)·14 citations
08
Impact of nuclear mass models on $r$ -process nucleosynthesis and heavy element abundances in $r$ -process enhanced metal-poor stars
Meng-Hua Chen · Li-Xin Li · En-Wei Liang · Ning Wang
Due to the lack of experimental data on extremely neutron-rich nuclei, theoretical values derived from nuclear physics models are essential for the rapid neutron capture process ( $r$ -process). Metal-poor stars enriched by the $r$ -process offer valuable cases for studying the impact of nuclear physics models on $r$ -process nucleosynthesis. This study analyzes four widely used nuclear physics models in detail: Finite-Range Droplet Model, Hartree-Fock-Bogoliubov, Duflo-Zuker, and Weizs $a ¨$ cker-Skyrme (WS4). Theoretical values predicted by the WS4 model are found to be in good agreement with experimental data, with deviations significantly smaller than those predicted by other models. The heavy element abundances observed in $r$ -process enhanced metal-poor stars can be accurately reproduced by $r$ -process nucleosynthesis simulations using the WS4 model, particularly for the rare earth elements. This suggests that nuclear data provided by nuclear physics model like WS4 are both essential and crucial for $r$ -process nucleosynthesis studies.
↳ astro-ph.HEastro-ph.SRnucl-thAstron.Astrophys.(2025)·2 citations
09
Effect of chiral imbalance on the electrical conductivity of hot and dense quark matter using Green-Kubo Method within the 2-flavour gauged NJL model
Snigdha Ghosh🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Sourav Sarkar🇮🇳 · Pradip Roy🇮🇳
The electrical conductivity of hot and dense quark matter is calculated using the 2-flavour gauged Nambu-Jona--Lasinio (NJL) model in the presence of a chiral imbalance quantified in terms of a chiral chemical potential (CCP). To this end, the in-medium spectral function corresponding to the vector current correlator is evaluated employing the real time formulation of finite temperature field theory. Taking the long wavelength limit of the spectral function we extract the electrical conductivity using the Green-Kubo relation. The thermal widths of the quarks/antiquarks that appear in the expression of electrical conductivity are calculated by considering the $2 \to 2$ scattering in the NJL model. The scattering amplitudes containing the polarization functions of the mesonic modes in the scalar and pseudoscalar channels are also evaluated by considering finite value of CCP. We find that the ratio of electrical conductivity to temperature has significant dependence on CCP especially in the low temperature region.
↳ hep-phnucl-thEPJC(2024)·2 citations
10
Constraints on color-flavor locked quark matter in view of the HESS J1731-347 measurement
K. Kourmpetis🇬🇷 · P. Laskos-Patkos🇬🇷 · Ch.C. Moustakidis🇬🇷
Astrophysical observations play a crucial role in understanding the processes within compact stars. A recent study measured the central object in the HESS J1731-347 supernova remnant (SNR), estimating its mass at $M = 0.7 7_{- 0.17}^{+ 0.20} M_{⊙}$ and radius at $R = 10.4 0_{- 0.78}^{+ 0.86} km$ , identifying it as the lightest neutron star ever observed. Conventional models suggest neutron stars form with a minimum gravitational mass of approximately $1.17 M_{⊙}$ , raising the question of whether this object is a typical neutron star or possibly an "exotic" star. To investigate, we utilize the Color-Flavor Locked (CFL) equation of state (EoS), integrating data from the HESS J1731-347 measurement with pulsar observations and gravitational wave detections. Additionally, we construct hybrid EoS by combining the MDI-APR1 (hadronic) and CFL (quark) EoS, introducing a phase transition through Maxwell construction. Our findings reveal that absolutely stable CFL quark matter effectively explains all observed measurements, including the central object of HESS J1731-347, whereas hybrid models incorporating the CFL MIT Bag model cannot account for the masses of the most massive observed pulsars.
↳ astro-ph.HEgr-qcnucl-thHNPS Adv.Nucl.Phys.(2025)·7 citations
11
Dissociation and regeneration of charmonia within microscopic Langevin simulations
Naomi Oei🇩🇪 · Juan M. Torres-Rincon🇪🇸 · Hendrik van Hees🇩🇪 · Carsten Greiner🇩🇪
We present a classical model to study the formation of charmonia, as well as dissociation and regeneration processes of heavy-quark bound states in the quark gluon plasma using Langevin simulations. The charm and anticharm quarks are described as Brownian particles in the background medium of light quarks and gluons and interact among them over a Coulomb-like screened potential to form bound states, which can dissociate again due to interactions with the medium. Box simulations at fixed temperature and volume are used to verify that the system reaches the expected thermal distribution in the equilibrium limit and to test bound state properties. The medium evolution is then parametrized by a boost-invariant fireball. In this configuration, the elliptic flow of charm and anticharm quarks as well as of charmonia is studied at RHIC and LHC energies.
↳ hep-phnucl-thPoS(2025)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE