Nuclear Theory·nucl-th

Friday·April 25, 2025

11 papers—6 primary·5 cross-listed

01
Inclusive Neutrino and Antineutrino Scattering on the $^{12}$ C Nucleus Within the Coherent Density Fluctuation Model
M. V. Ivanov🇧🇬 · A. N. Antonov🇧🇬
We investigate quasielastic (anti)neutrino scattering on the $^{12}$ C nucleus utilizing a novel scaling variable, $ψ^{*}$ . This variable is derived from the interacting relativistic Fermi gas model, which incorporates both scalar and vector interactions, leading to a relativistic effective mass for the interacting nucleons. For inclusive lepton scattering from nuclei, we develop a new scaling function, denoted as $f^{QE} (ψ^{*})$ , based on the coherent density fluctuation model (CDFM). This model serves as a natural extension of the relativistic Fermi gas (RFG) model applicable to finite nuclei. In this study, we compute theoretical predictions and compare them with experimental data from Miner $ν$ a and T2K for inclusive (anti)neutrino cross-sections. The scaling function is derived within the CDFM framework, employing a relativistic effective mass of $m_{N}^{*}$ = 0.8 $m_{N}$ . The findings demonstrate a high degree of consistency with experimental data across all (anti)neutrino energy ranges.
nucl-thUniverse(2025)·1 citation
02
A physics-embedded Bayesian neural network for predicting the energy dependence of fission product yields with fine structures
Jingde Chen · Yuta Mukobara · Kazuki Fujio · Satoshi Chiba · Tatsuya Katabuchi · Chikako Ishizuka
We present a physics-embedded Bayesian neural network (PE-BNN) framework that integrates fission product yields (FPYs) with prior nuclear physics knowledge to predict energy-dependent FPY data with fine structure. By incorporating an energy-independent phenomenological shell factor as a single input feature, the PE-BNN captures both fine structures and global energy trends. The combination of this physics-informed input with hyperparameter optimization via the Watanabe-Akaike Information Criterion (WAIC) significantly enhances predictive performance. Our results demonstrate that the PE-BNN framework is well-suited for target observables with systematic features that can be embedded as model inputs, achieving close agreement with known shell effects and prompt neutron multiplicities.
nucl-thnucl-exphysics.data-anPRC(2026)·0 citations
03
Exploring the giant monopole resonance in superheavy nuclei: A theoretical perspective
S. Kumar · Jeet Amrit Pattnaik · S. K. Singh · R. N. Panda · M. Bhuyan · S. K. Patra
Within the relativistic mean field framework, in an extended Thomas-Fermi approximation, we calculate the binding energy and charge distribution radius for the latest superheavy nuclei, synthesised in various laboratories, with atomic numbers $Z = 110 - 118$ . The binding energy and radii are compared with the results obtained from relativistic Hartree calculations along with the experimental data, wherever available, to check the reliability of the methods. The calculations are extended to estimate the giant monopole resonances to understand the collective vibration of the nucleons for such superheavy nuclei. The giant monopole resonances obtained from scaling calculations are compared with the constraint computations. Furthermore, the results are compared with other known methods, such as the relativistic Random Phase Approximation (RPA) and time-dependent mean field calculations, along with some known lighter nuclei, specifically Zr isotopes (N = 42-86) and O isotopes (N = 10-36). Finally, the nuclear compressibility of the superheavy nuclei is predicted from the energy obtained in the breathing mode.
nucl-thnucl-exPhys.Part.Nucl.Lett.(2026)·0 citations
04
Directed and elliptic flow of light nuclei and hypernuclei in Au+Au collisions at $s_{NN} = 3$ GeV: Coalescence vs. Statistical Fragmentation
Tom Reichert🇩🇪 · Manjunath Omana Kuttan🇩🇪 · Apiwit Kittiratpattana🇹🇭 · Nihal Buyukcizmeci🇹🇷 · Alexander Botvina🇩🇪 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪
The harmonic flow coefficients of light nuclei and hypernuclei in Au+Au collisions at $s_{NN} = 3$ GeV are investigated using the Ultra-relativistic Quantum Molecular Dynamics transport model. For the Equation-of-State we employ a density and momentum dependent potential from the Chiral-Mean-Field model. Light nuclei and hypernuclei production is described at kinetic freeze-out via a coalescence mechanism or with a statistical multi-fragmentation calculation. The directed flow $v_{1}$ of p, d, t, $^{3}$ He, $^{4}$ He as well as the $Λ$ , $_{Λ}^{3}$ H and $_{Λ}^{4}$ H is shown to approximately scale with mass number $A$ of the light cluster in both calculations. This is in agreement with the experimental results for the directed flow measured by STAR. Predictions for the directed and elliptic flow of (hyper)nuclei at further RHIC-FXT and FAIR energies show that the scaling properties should improve as the beam energy is increased.
nucl-thnucl-exPRC(2025)·5 citations
05
Study of QCD critical point with three-nucleon correlations in light nuclei yields ratios using PYTHIA8/Angantyr
Zuman Zhang🇨🇳 · Ning Yu🇨🇳 · Sha Li🇨🇳 · Shuang Li🇨🇳 · Siyu Tang🇨🇳 · Meimei Zhang🇨🇳
This study utilizes the PYTHIA8 Angantyr model to systematically investigate the effects of three nucleons correlation $C_{n^{2} p}$ on the light nuclei yield ratio $N_{t} N_{p} / N_{d}^{2}$ in Au+Au collisions at $s_{NN}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV. The analysis explores this property across different rapidity ranges, collision centralities, and collision energies, while also examining the roles of multi-parton interactions (MPI) and color reconnection (CR) mechanisms. The results show that the light nuclei yield ratio remains stable with changes in rapidity coverage and collision centrality but slightly increases with rising collision energy. The impact of CR on the light nuclei yield ratio depends entirely on the presence of MPI; when MPI is turned off, CR has no effect. Additionally, the three-nucleon correlation, enhances the light nuclei yield ratio in both central and peripheral collisions. However, the non-monotonic energy dependence observed in experiments, the peak at $s_{NN}$ = $20 \sim 30$ GeV reported by the STAR experiment, cannot be explained by the Angantyr model due to its lack of key mechanisms related to the quark-gluon plasma (QGP). Nevertheless, the Angantyr model serves as an important baseline for studying collision behaviors in the absence of QGP effects.
nucl-thhep-thCPC(2025)·1 citation
06
Exact solutions for the moments of the binary collision integral and its relation to the relaxation-time approximation in leading-order anisotropic fluid dynamics
Etele Molnár🇵🇱
We compute the moments of the nonlinear binary collision integral in the ultrarelativistic hard-sphere approximation for an arbitrary anisotropic distribution function in the local rest frame. This anisotropic distribution function has an angular asymmetry controlled by the parameter of anisotropy $ξ$ , such that in the limit of a vanishing anisotropy $lim_{ξ \to 0} f^_{0 k} = f_{0 k}$ , approaches the spherically symmetric local equilibrium distribution function. The corresponding moments of the binary collision integral are obtained in terms of quadratic products of different moments of the anisotropic distribution function and couple to a well defined set of lower-order moments. To illustrate these results we compare the moments of the binary collision integral to the moments of the widely used relaxation-time approximation of Anderson and Witting in case of a spheroidal distribution function. We found that in an expanding system the nonlinear Boltzmann collision term leads to twice slower equilibration than the relaxation-time approximation. Furthermore we also show that including two dynamical moments helps to resolve the ambiguity which additional moment of the Boltzmann equation to choose to close the conservation laws.
nucl-thhep-phphysics.flu-dynPRD(2025)·0 citations
07
Baryon Number Violation: From Nuclear Matrix Elements to BSM Physics
Leah J. Broussard🇺🇸 · Andreas Crivellin🇨🇭 · Martin Hoferichter🇨🇭 · Sergey Syritsyn🇺🇸 · Yasumichi Aoki🇯🇵 · Joshua L. Barrow🇺🇸 · Arnau Bas i Beneito🇪🇸 · Zurab Berezhiani🇮🇹 · Nicola Fulvio Calabria🇮🇹 · Svjetlana Fajfer🇸🇮 · Susan Gardner🇺🇸 · Julian Heeck🇺🇸 and 10 other authors
Processes that violate baryon number, most notably proton decay and $n n ˉ$ transitions, are promising probes of physics beyond the Standard Model (BSM) needed to understand the lack of antimatter in the Universe. To interpret current and forthcoming experimental limits, theory input from nuclear matrix elements to UV complete models enters. Thus, an interplay of experiment, effective field theory, lattice QCD, and BSM model building is required to develop strategies to accurately extract information from current and future data and maximize the impact and sensitivity of next-generation experiments. Here, we briefly summarize the main results and discussions from the workshop "INT-25-91W: Baryon Number Violation: From Nuclear Matrix Elements to BSM Physics," held at the Institute for Nuclear Theory, University of Washington, Seattle, WA, January 13-17, 2025.
↳ hep-phhep-exhep-latnucl-ex+1J.Phys.G(2025)·10 citations
08
Charge Radii Measurements of Exotic Tin Isotopes in the Proximity of $N = 50$ and $N = 82$
F.P. Gustafsson🇧🇪 · L. V. Rodríguez🇩🇪 · R.F. Garcia Ruiz🇺🇸 · T. Miyagi🇯🇵 · S.W. Bai🇨🇳 · D.L. Balabanski🇷🇴 · C.L. Binnersley🇬🇧 · M.L. Bissell🇬🇧 · K. Blaum🇩🇪 · B. Cheal🇬🇧 · T.E. Cocolios🇧🇪 · G.J. Farooq-Smith🇧🇪 and 42 other authors
We report nuclear charge radii for the isotopes $^{104 - 134}$ Sn, measured using two different collinear laser spectroscopy techniques at ISOLDE-CERN. These measurements clarify the arch-like trend in charge radii along the isotopic chain and reveal an odd-even staggering that is more pronounced near the $N = 50$ and $N = 82$ shell closures. The observed local trends are well described by both nuclear density functional theory and valence space in-medium similarity renormalization group calculations. Both theories predict appreciable contributions from beyond-mean-field correlations to the charge radii of the neutron-deficient tin isotopes. The models, however, fall short of reproducing the magnitude of the known $B (E 2)$ transition probabilities, highlighting the remaining challenges in achieving a unified description of both ground-state properties and collective phenomena.
↳ nucl-exnucl-thPRL(2025)·21 citations
09
Gaussian generally covariant hydrodynamics
G.M.Sampaio🇧🇷 · G.Rabelo-Soares🇧🇷 · G.Torrieri🇧🇷
We develop a version of fluctuating relativistic hydrodynamics in a way very different from the usual derivation: Instead of treating it as a coarse-grained deterministic theory expanded in gradients of equilibrium quantities, we treat it as a stochastic theory, characterized by partition functions in each cells, expanded in cumulants. We show that the Gaussian ansatz allows us, via the gravitational Ward identities acting as a constraint between the variance and the average, to maintain full general covariance, with hydrodynamic flow emerging as an approximate Killing vector. If the symmetry of relativistic hydrodynamics, volume-preserving diffeomorphisms, is preserved, we show that linear response formulae are also generally covariant. We discuss our results and argue that in this approach, the applicability of the effective theory is parametrized around a very different quantity than the Knudsen number, offering hope of understanding the applicability of hydrodynamics to small systems.
↳ hep-thgr-qchep-phnucl-thPRD(2025)·8 citations
10
(2+2)D Collective Model based on a relativistic Boltzmann equation in the Isotropization Time Approximation: CoMBolt-ITA
S. F. Taghavi🇩🇪 · S. M. A. Tabatabaee Mehr🇮🇷 · F. Taghinavaz🇮🇷
A new model based on the relativistic Boltzmann equation in the isotropization time approximation is developed to investigate the collective behavior of the quark-gluon plasma produced in high-energy heavy-ion collisions. The equation is solved in (2+2)D (two spatial and two momentum-space dimensions). This framework couples pre-equilibrium dynamics with hydrodynamic evolution to simulate the dynamics of quasiparticle evolution. A numerical scheme based on the method of characteristics enables the evolution to begin from a specified initial Boltzmann distribution. In this work, the spatial structure of the initial distribution is modeled using the TrENTo framework. Our results show that a medium initialized at $τ_{0}$ on the order of 1 [fm/ $c$ ] with a small shear viscosity to entropy density ratio ( $η / s = 0.008$ ) evolves consistently with hydrodynamic simulations, such as those performed using the VISH2+1 code, while discrepancies arise for a medium with $η / s = 0.8$ . Furthermore, when initialized with a highly anisotropic momentum distribution in the longitudinal direction at early times, the system exhibits spatially non-uniform thermalization in the transverse plane, leading to the emergence of a nontrivial hypersurface that marks the onset of hydrodynamic applicability. Finally, we compute the $p_{T}$ -spectra for a non-fluctuating initial condition using the hybrid version of CoMBolt-ITA. In this hybrid setup, the description is switched from quasiparticles to hadrons, and UrQMD is used to model the hadron gas dynamics. We compare these results with those obtained from the hybrid VISH2+1 initialized within the same setup. For a small shear viscosity, $η / s = 0.08$ , the two results show a good level of consistency, whereas for a larger value, $η / s = 0.8$ , a noticeable discrepancy emerges.
↳ hep-phhep-thnucl-thPRC(2026)·2 citations
11
Flux tube clustering from magnetic coupling of adjacent type-I and -II superconductors in a neutron star: persistent gravitational radiation
K. H. Thong · A. Melatos
Adjacent type-I and -II proton superconductors in a rotation-powered pulsar are predicted to exist in a metastable state containing macroscopic and quantized flux tubes, respectively. Previous studies show that the type-I and -II regions are coupled magnetically, when macroscopic flux tubes divide dendritically into quantized flux tubes near the type-I-II interface, through a process known as flux branching. The studies assume that the normal-superconducting boundary is sharp, and the quantized flux tubes do not repel mutually. Here the sharp-interface approximation is refined by accounting for magnetic repulsion. It is found that flux tubes in the same flux tree cluster with a minimum-energy separation two to seven times less than that of isolated flux tubes. Neutron vortices pin and cluster about flux trees. We find that the maximum characteristic wave strain $h_{0}$ of the current quadrupole gravitational radiation emitted by a rectilinear array of clustered vortices exceeds by $(1 + N_{v, t})^{1/2}$ the strain $h_{0} \sim 1 0^{- 32} (f /30 Hz)^{5/2} (D /1 kpc)^{- 1}$ emitted by uniformly distributed vortices, where $N_{v, t}$ is the mean number of pinned vortices per flux tree, $f$ is the star's spin frequency, and $D$ is the star's distance from Earth. The factor $(1 + N_{v, t})^{1/2}$ brings $h_{0}$ close to the sensitivity limit of the current generation of interferometric gravitational wave detectors under certain circumstances, specifically when flux branching forms relatively few (and hence relatively large) flux trees.
↳ astro-ph.HEcond-mat.quant-gascond-mat.supr-congr-qc+1MNRAS(2025)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE