Nuclear Theory·nucl-th

Thursday·September 12, 2024

12 papers—5 primary·7 cross-listed

01
Alpha decay law of excited nuclei and its role in stellar decay rates
D. F. Rojas-Gamboa · N. G. Kelkar · O. L. Caballero
$α$ decay is one of the prominent decay modes in the nucleosynthesis of heavy and super-heavy elements synthesized at temperatures of the order of Giga Kelvin. To facilitate the investigation of the role played by the $α$ decay half-lives of thermally excited nuclei in nucleosynthesis calculations, an empirical formula based on a model for the $α$ decay of nuclei in their ground and excited states to daughter nuclei in their ground or excited states is presented. Constants appearing in the analytical expression for the $α$ decay half-life obtained within the model are treated as adjustable parameters and fitted to experimental data on 342 $α$ decays in the range of 82 $\leq Z_{p} \leq$ 94, to obtain an excitation energy-dependent decay law. Under the assumption that thermal equilibrium has been reached between nuclear states, temperature ( $T$ )-dependent half-lives, $t_{1/2} (T)$ , for several of the experimentally studied $α$ emitters with 65 $\leq Z_{p} \leq$ 94 are presented using available data on the half-lives of excited nuclei. Though the general trend is a decrease in $t_{1/2} (T)$ at elevated temperatures, exceptional cases with increased half-lives are found in the case of some isomeric states. A list of such isomers provided in this work motivates future work involving considerations of their thermal equilibration and role in shaping kilonova light curves.
nucl-thastro-ph.SRnucl-exPRC(2024)·5 citations
02
Phase Stability in the 3-Dimensional Open-source Code for the Chiral mean-field Model
Nikolas Cruz-Camacho🇺🇸 · Rajesh Kumar🇺🇸 · Mateus Reinke Pelicer🇺🇸 · Jeff Peterson🇺🇸 · T. Andrew Manning🇺🇸 · Roland Haas🇺🇸 · Veronica Dexheimer🇺🇸 · Jaquelyn Noronha-Hostler🇺🇸
In this paper we explore independently for the first time three chemical potentials (baryon $μ_{B}$ , charged $μ_{Q}$ , and strange $μ_{S}$ ) in the Chiral Mean Field (CMF) model. We designed and implemented \texttt{CMF++}, a new version of the CMF model rewritten in \texttt{C++} that is optimized, modular, and well-documented. \texttt{CMF++} has been integrated into the MUSES Calculation Engine as a free and open-source software module. The runtime improved in more than 4 orders of magnitude across all 3 chemical potentials, when compared to the legacy code. Here we focus on the zero temperature case and study stable, as well as metastable and unstable, vacuum, hadronic, and quark phases, showing how phase boundaries vary with the different chemical potentials. Due to the significant numerical improvements in \texttt{CMF++}, we can now for the first time sweep the entire $μ_{B}$ , $μ_{S}$ , $μ_{Q}$ phase space, investigate metastable phases, and calculate high-order susceptibilities within the CMF framework. This allows us to find phases of matter that include a light hadronic phase, a strangeness-dominated hadronic phase, and a quark phase. The numerical improvements also allow us to identify the order of the transitions among these phases, finding a first-order chiral symmetry restoration phase transition among the hadronic phases (favored for negative $μ_{Q}$ and/or $μ_{S}$ for some coupling schemes), in addition to third-order phase transitions. In particular, we identify for the first time triple points in the CMF model, where both chiral symmetry restoration and deconfinement phase transitions meet in the chemical potential phase space. Such points could potentially be identified in low-energy heavy-ion collisions.
nucl-thastro-ph.HEhep-phPRD(2025)·29 citations
03
Neutron skin and its effects in heavy-ion collisions
Meng-Qi Ding🇨🇳 · De-Qing Fang🇨🇳 · Yu-Gang Ma🇨🇳
Neutron skin is an exotic phenomena in unstable nuclei. The various effects in nuclear reactions caused by the neutron skin and also its relation with the properties of nuclear structure are reviewed in this article. Based on numerous studies with theoretical models, strong correlations have been found between the neutron skin thickness and neutron removal cross section, neutron/proton yield ratio, t/\ch{^3He} yield ratio, neutron-proton momentum difference, isoscaling parameter, photon production, reaction cross sections for neutron induced reactions, charge-changing cross sections difference of mirror nuclei, astrophysical $S$ -factor, and other quantities in nuclear reactions induced by neutron-rich nuclei. Moreover, the relationships between neutron skin thickness and some properties of nuclear structure, such as $α$ -cluster formation, $α$ decay, nuclear surface, nuclear temperature, and proton radii difference of mirror nuclei, have also been investigated. It also has been shown that the neutron skin plays a crucial role in relativistic heavy-ion collisions. Experimentally, an unstable nucleus with neutron skin can be generated by radioactive nuclear beam facilities, and the thickness of neutron skin could be extracted by measuring the sensitive probes, which further helps giving stringent constraints on the equation of state of asymmetric nuclear matter and properties of neutron stars.
nucl-thnucl-exNucl.Sci.Tech.(2024)·29 citations
04
Resummed spin hydrodynamics from quantum kinetic theory
David Wagner🇮🇹
In this work, the equations of dissipative relativistic spin hydrodynamics based on quantum kinetic theory are derived. Employing the inverse-Reynolds dominance (IReD) approach, a resummation scheme based on a power counting in Knudsen and inverse Reynolds numbers is constructed, leading to hydrodynamic equations that are accurate to second order. It is found that the spin dynamics can be characterized by eleven equations: six of them describe the evolution of the components of the spin potential, while the remaining five provide the equation of motion of a dissipative irreducible rank-two tensor. For a simple truncation, the first- and second-order transport coefficients are computed explicitly.
nucl-thPRD(2025)·29 citations
05
Ab initio Green's functions approach for homogeneous nuclear matter
Francesco Marino · Carlo Barbieri · Gianluca Colò · Weiguang Jiang · Samuel J. Novario
Homogeneous nuclear matter is investigated using the \textit{ab initio} Self-consistent Green's function (SCGF) approach with nuclear interactions based on chiral effective field theory. The employed method, which combines the state-of-the-art algebraic diagrammatic construction approximation at third order with Gorkov correlations, is capable of computing both the equation of state (EOS) and single-particle properties of nuclear matter. The EOS calculated with our approach and coupled-cluster theory are shown to agree very well. The one-nucleon spectral functions and the momentum distributions are discussed to gain insights into the dynamics of the interacting nuclear matter.
nucl-thcond-mat.quant-gascond-mat.str-elPoS(2025)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE

Alpha decay law of excited nuclei and its role in stellar decay rates

Phase Stability in the 3-Dimensional Open-source Code for the Chiral mean-field Model

Neutron skin and its effects in heavy-ion collisions

Resummed spin hydrodynamics from quantum kinetic theory

Ab initio Green's functions approach for homogeneous nuclear matter

Affiliations