Nuclear Theory·nucl-th

Wednesday·December 25, 2024

10 papers—5 primary·5 cross-listed

01
Emulation of the final r-process abundance pattern with a neural network
Yukiya Saito · Iris Dillmann · Reiner Krücken · Matthew R. Mumpower · Rebecca Surman
This work explores the construction of a fast emulator for the calculation of the final pattern of nucleosynthesis in the rapid neutron capture process (the $r$ -process). An emulator is built using a feed-forward artificial neural network (ANN). We train the ANN with nuclear data and relative abundance patterns. We take as input the $β$ -decay half-lives and the one-neutron separation energy of the nuclei in the rare-earth region. The output is the final isotopic abundance pattern. In this work, we focus on the nuclear data and abundance patterns in the rare-earth region to reduce the dimension of the input and output space. We show that the ANN can capture the effect of the changes in the nuclear physics inputs on the final $r$ -process abundance pattern in the adopted astrophysical conditions. We employ the deep ensemble method to quantify the prediction uncertainty of the neutal network emulator. The emulator achieves a speed-up by a factor of about 20,000 in obtaining a final abundance pattern in the rare-earth region. The emulator may be utilized in statistical analyses such as uncertainty quantification, inverse problems, and sensitivity analysis.
nucl-thnucl-exJ.Phys.G(2025)·2 citations
02
Alpha-Particle Monopole Form Factors with Ab Initio No-Core Shell Model
P. Yin · A. M. Shirokov · H. Li · B. Zhou · X. Zhao · S. Bacca · J. P. Vary
The state-of-the-art ab initio nuclear many-body approaches with modern nuclear forces are challenged by the recent experimental measurement of the monopole form factor of the $0_{1}^{+} \to 0_{2}^{+}$ transition in the $α$ particle [Kegel et al., Phys. Rev. Lett. 130, 152502 (2023)]. We investigate the elastic and inelastic $0_{1}^{+} \to 0_{2}^{+}$ transition form factors using the ab initio no-core shell model (NCSM). We observe a good convergence of both form factors with respect to the basis size employing the Daejeon16 nucleon-nucleon ( $N N$ ) interaction. Our NCSM results are very close to the effective interaction hyperspherical harmonic calculations using $N N$ plus three-nucleon interactions based on the chiral effective field theory which take into account the continuum effects via the Lorentz integral transform. The significant difference between the ab initio results with various modern nuclear interactions and of some of them with the recent experimental data provides motivations for deeper investigation of this observable.
nucl-thnucl-exPRC(2025)·3 citations
03
Chirality in $(p, 2 p)$ reactions induced by proton helicity
Tomoatsu Edagawa🇯🇵 · Kazuki Yoshida🇯🇵 · Shoichiro Kawase🇯🇵 · Kazuyuki Ogata🇯🇵 · Masaki Sasano🇯🇵
It is shown that longitudinally polarized protons can be used to induce chirality in the final states of the $(p, pN)$ reaction at intermediate energies, when there exist three final-state particles with non-coplanar momentum vectors. The analyzing power $A_{z}$ is proposed as a measure of this effect. Theoretical descriptions to obtain $A_{z}$ based on an intuitive picture as well as a distorted wave impulse approximation are presented, showing that the helicity of incident protons is coupled to the chirality of the orbital motion of a single-particle wave function, resulting in the chirality of the final states and a large $A_{z}$ value.
nucl-thnucl-exPRC(2026)·0 citations
04
Fermionic equations of motion in strongly-correlated media: applications to the nuclear many-body problem
Elena Litvinova🇺🇸
These notes summarise the lectures given at the International School of Physics "Enrico Fermi" in Summer 2024 in Varenna (Italy) about the strongly coupled quantum many-body theory and its applications to nuclear structure. The lectures present a rather short overview of the subject with an emphasis on the analytical aspects of the nuclear many-body problem, aiming at a deep understanding of the complexity of strongly coupled nucleonic states and emergent collective phenomena. The major pedagogical focus is recognizing how all the models describing nuclear dynamics follow from a unified model-independent framework formulated in the universal language of quantum field theory. In particular, connections between the classes of ab initio, density functional theory, and beyond mean-field approaches are made accessible. Approximations of varying complexity are discussed in applications to excited states of medium-heavy nuclei.
nucl-thnucl-ex0 citations
05
Global analysis of the non-uniformity of nucleon density distributions
Shuichiro Ebata · Wataru Horiuchi
Background: Saturation of nuclear density is a fundamental property of atomic nuclei but in reality, the nuclear internal density distribution is not uniform, e.g., some nuclei are known to have the so-called bubble structure, in which the central density is depressed. Purpose: We aim to unveil the emergent mechanism of the non-uniformity of the nucleon density distributions for whole nuclear mass regions, not only for a typical bubble structure. Method: We systematically investigate the nucleon density distributions using the Skyrme Hartree-Fock plus Bardeen-Cooper-Schrieffer calculation represented in the three-dimensional Cartesian coordinate space. The ground states of 1,389 even-even nuclei are generated. To quantify the nonuniformity of these density distributions, a ``generalized bubble parameter" is introduced. Results: We find that the bubble structure appears around the magic numbers, which correspond to the regions where the s orbit appears near the Fermi surface. The nuclear deformation and pairing correlations strongly affect the occupation probability, but the robust bubble structure of a medium mass nucleus, $^{100}$ Sn, is found. We confirm that the Coulomb force enhances the bubble degree in the superheavy region. The nuclear non-uniformity is further generalized by the ``multi-layered" bubble structure, which exhibits some density depression in the internal regions of the density distributions. Conclusion: The non-uniformity of the internal density distribution occurs due to the deficiency of the specific single-particle orbits: the nodal $s$ , $p$ , and $d$ orbits. This is certainly reflected in the density distribution near the nuclear surface, which can be deduced from proton-elastic scattering.
nucl-thPRC(2025)·3 citations
06
Improving $π π$ dispersive analyses and resonance determination with Forward Dispersion Relations
P. Rabán🇪🇸 · J.R. Peláez🇪🇸 · J. Ruiz de Elvira🇪🇸
We present preliminary results of an improved pion-pion scattering dispersive analysis that includes: a refined treatment of inelasticities, the introduction of G-waves, the extension of Forward Dispersion Relations as constraints up to 1.6 GeV, and data description up to roughly 1.8 GeV. Additionally, we impose Roy-like dispersion relations. As a result, we obtain three reliable solutions corresponding to three different datasets. From the Forward Dispersion Relation output, we extract resonance pole parameters in a parameterization-independent way using continued fractions.
↳ hep-phhep-exhep-latnucl-thPoS(2025)·0 citations
07
Low-Energy Neutrino-Nucleus Scattering and New Physics
S. Carey🇺🇸 · V. Pandey🇺🇸
The interactions of low-energy neutrinos with nuclei provide a unique window to explore various Standard Model (SM) and Beyond the Standard Model (BSM) processes. In particular, the recent observation of coherent elastic neutrino-nucleus scattering (CEvNS), predicted over five decades ago, has generated significant interest across disciplines. With its high cross section and suitability for compact detectors, particularly with stopped pion neutrinos, CEvNS offers a powerful probe for light, weakly coupled new physics. Ongoing global experimental efforts now aim to leverage CEvNS to test SM predictions and search for BSM signals, where deviations in event rates or spectra could reveal new physics. We present here an estimate of the number of recoil events obtained from CEvNS using the current and upcoming liquid argon based experiments. Furthermore, the event rate due to the inclusion of neutrino magnetic moment is also discussed.
↳ hep-phhep-exnucl-exnucl-th1 citation
08
Heavy-Quark Spin Symmetry Violation effects in Charmed Baryon Production
Nantana Monkata🇹🇭 · Prin Sawasdipol🇹🇭 · Nongnapat Ponkhuha🇹🇭 · Ratirat Suntharawirat🇹🇭 · Ahmad Jafar Arifi🇯🇵 · Daris Samart🇹🇭
In this work, we investigate the Heavy-Quark Spin Symmetry (HQSS) exhibited in the effective Lagrangians governing the three-point interactions of $D$ mesons, charmed baryons, and nucleons. We first construct the effective Lagrangians, and there are 12 distinct terms. As a result, we observe that the invariant Lagrangian under HQSS manifests exclusively in the pseudoscalar $D$ mesons coupling to nucleons and $Λ_{c}$ baryons, whereas nucleons and $Σ_{c}$ ( $Σ_{c}^{*}$ ) baryons only couple with vector $D$ mesons. By taking into account the violated heavy-quark spin transformation, one can recover all interactions from the effective Lagrangians. Furthermore, we compute the differential cross-sections of the $p p ˉ \to Y_{c} Y ˉ_{c}^{'}$ scatterings, where $Y_{c}, Y_{c} ˉ^{'} = Λ_{c}, Σ_{c}, Σ_{c}^{*}$ , to reveal the residue of the violating HQSS (VHQSS) on charmed baryon production. Ultimately, by accounting for VHQSS, we aim for precise predictions of production rates, which are essential for the High-Energy Storage Ring (HESR) experiments at the Facility for Antiproton and Ion Research (FAIR).
↳ hep-phnucl-th0 citations
09
Using the Th III Ion for a Nuclear Clock and Searches for New Physics
V. A. Dzuba🇦🇺 · V. V. Flambaum🇦🇺
The 229Th nucleus possesses a unique low-frequency transition at 8.4 eV, which is being considered for the development of an extremely accurate nuclear clock. We investigate an electronic bridge process in the Th III ion, where nuclear excitation occurs via electronic transitions, and demonstrate that a proper choice of laser frequencies can lead to 10,000 enhancement of this effect. Electrons also reduce 1.7 times the lifetime of the nuclear excited state. Additionally, the electronic structure of the Th III ion exhibits features that make it particularly useful for probing new physics. Notably, it contains a metastable state connected to the ground state via a weak M2 transition, which can be utilized for quantum information processing, as well as searches for oscillating axion field, violation of local Lorentz invariance, test of the Einstein's equivalence principle, and measurement of nuclear weak quadrupole moment. The electronic states of the ion present a unique case of level crossing involving the 5f, 6d, and 7s single-electron states. This crossing renders the transition frequencies highly sensitive to potential time-variation of the fine-structure constant.
↳ physics.atom-phhep-phnucl-thPRA(2025)·4 citations
10
Non-radial oscillations of hadronic neutron stars, quark stars, and hybrid stars : Calculation of $f$ , $p$ , and $g$ mode frequencies
Atanu Guha🇰🇷 · Debashree Sen🇰🇷 · Chang Ho Hyun🇰🇷
The composition and equation of state (EoS) of dense matter relevant to compact stars are quite inconclusive. However, certain observational constraints on the structural properties of compact stars help us constrain the EoS to a fair extent. Moreover, gravitational asteroseismology gives a notion of the composition and EoS of compact stars. The next generation gravitational wave (GW) detectors are likely to detect several oscillation mode frequencies of the GWs. In this work we compute the fundamental ( $f$ ) and the first pressure ( $p_{1}$ ) mode frequencies ( $f_{f}$ and $f_{p 1}$ , respectively) with different compositions viz., hadronic, quark, and hybrid star (HS) matter. For HSs, we also study the gravity ( $g$ ) mode frequency ( $f_{g}$ ). For each phase we also study the correlation between the oscillation frequencies of 1.4 $M_{⊙}$ and 2.01 $M_{⊙}$ compact stars with other different properties. We find that various possible composition of compact stars substantially affects the oscillation frequencies. However, the mass-scaled angular $f$ mode frequency ( $ω_{f} M$ ) varies universally with compactness ( $C$ ) for all hadronic, quark and hybrid stars. The $f$ mode frequency ( $f_{f_{1.4}}$ ) of the canonical 1.4 $M_{⊙}$ compact star, obtained with different composition, is quite correlated with the canonical radius ( $R_{1.4}$ ) and tidal deformability ( $Λ_{1.4}$ ) while $f_{p_{1.4}}$ is well correlated with slope parameter of the symmetry energy. We also show that $f_{g_{1.4}}$ of the HSs varies almost linearly with $Λ_{1.4}$ . Should $g$ modes be detected, they could not only support the existence of HSs, but $f_{g}$ could be useful to understand the strength of quark repulsion in HSs.
↳ hep-phastro-ph.HEnucl-thEPJC(2025)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE