Nuclear Theory·nucl-th

Tuesday·May 19, 2026

21 papers—10 primary·11 cross-listed

01
One- and two-nucleon transfer in $^{116}$ Sn+ $^{60}$ Ni: A coupled reaction channel analysis
Chandra Kumar · S. Nath
Recent studies of multi-nucleon transfer in heavy ion collisions have employed both macroscopic and microscopic models. Although macroscopic approaches offer useful insights, microscopic analyses of high-precision experimental data provide a more reliable framework for understanding the nucleon transfer mechanisms. The present study aims to carry out a comprehensive theoretical investigation of the $^{116}$ Sn+ $^{60}$ Ni system using microscopic coupled reaction channel (CRC) calculations. The calculations employ microscopic double-folding S $a ~$ o Paulo potentials, incorporating all relevant inelastic and transfer couplings guided by observed $γ$ -ray transitions, wherever available. For the one-nucleon transfer channels, spectroscopic amplitudes are also obtained from large-scale shell-model calculations. In the case of two-nucleon transfer, sequential, microscopic cluster and extreme cluster mechanisms are considered to reproduce the data. Results for quasielastic scattering and one-neutron ( $1 n$ ) transfer show excellent agreement with experimental data. Measured one-proton ( $1 p$ ) transfer probabilities are best described by incorporating experimental spectroscopic amplitudes in the CRC calculations. For transfer of two-nucleons, the extreme cluster mechanism is found to best reproduce the data. This study highlights that microscopic description of one- and two-nucleon transfer between two heavy ions in the CRC framework, without taking recourse to arbitrary normalization of the cross sections, is quite feasible. Nonetheless, lack of experimental corroboration for all the transitions included in the calculations and practical limits of computational resources, affecting accuracy of shell-model results and causing a cap on the number of states, leave room for further refinement of the results.
nucl-th0 citations
02
2N and 3N Tensor Force in the $N = 34$ Shell Evolution: An Ab Initio Perspective
Anil Kumar · Takayuki Miyagi · Noritaka Shimizu
Shell evolution plays a vital role in understanding the nuclear shell structures across the nuclear chart. In this work, we have investigated the $N = 34$ shell structure using the state-of-the-art ab-initio valence-space in-medium similarity renormalization (VS-IMSRG) approach. Notably, we employ nucleon-nucleon (NN) and three-nucleon (3N) interactions derived from chiral effective field theory and make use of the spin-tensor decomposition scheme to examine the contributions of individual interaction components. We discuss the evolution of the shell structures, which have been investigated by considering the roles of various components, including central, spin-orbit, and tensor effects of NN and 3N forces, respectively. The $N = 34$ shell gap gradually decreases from $^{54}$ Ca as the proton occupancy in the $π 0 f_{7/2}$ orbital increases, and eventually disappears in the $^{62}$ Ni as a consequence of the tensor-force driven shell evolution. Our analysis reveals that this disappearance is predominantly governed by the NN tensor force, which accounts for approximately 83 $%$ , while the 3N tensor force also contributes about 17 $%$ .
nucl-thnucl-exPLB(2026)·1 citation
03
A self-consistent spectral framework for inclusive non-elastic breakup, with the Trojan Horse method as the sub-Coulomb resonant limit
Jin Lei
At the keV-scale energies of stellar nucleosynthesis, the resonant charged-particle reactions addressed by the Trojan Horse Method (THM) proceed through isolated near-threshold resonances, so the low-energy cross section and the resonance strength carry the same information, up to a normalization to reference resonances of known strength. Whether the standard THM working formula is accurate there has not been assessed in a controlled framework. I provide a self-consistent framework that computes the sub-Coulomb resonant THM extraction directly from the Ichimura-Austern-Vincent (IAV) inclusive non-elastic breakup cross section. The absorptive participant-target potential is represented by a diagonal isolated-pole spectral ansatz with three explicit validity conditions, two closing as dimensionless bounds from R-matrix tabulations and the third a model-dependent continuum-decoupling diagnostic. In the isolated-resonance limit the inclusive cross section reduces to a per-pole distorted-wave Born approximation (DWBA) cross section on the resonance state, carrying full entrance and exit distortions together with the post-form interaction and weighted by the channel branching ratio; this per-pole cross section is the controlled quantity for resonance-strength extraction. A three-layer Feshbach decomposition fixes the spectral pole half-width as half the non-elastic decay width, equal to half the total width in the sub-Coulomb limit, resolving the width, sign, and partial-width ambiguities of the literature. The standard factorized THM formula follows as a non-perturbative reduction under four explicit approximations, plane-wave entrance and exit waves, surface-localized spectator-participant interaction, on-shell binary amplitude, and post-form remnant neglect, so that its discarded content, the partial-wave coherence and the post-form remnant, is made explicit.
nucl-th0 citations
04
Parity violation in atoms: neutrino-mediated long range forces and finite nuclear size
Mikhail Gorchtein🇩🇪 · Hubert Spiesberger🇩🇪
We consider neutral-current parity-violating interactions in an atom mediated by the exchange of a neutrino-antineutrino pair. We explicitly account for the nuclear finite size encoded in the nuclear form factor. Based on its general properties, we derive an effective neutrino-mediated potential and determine its properties at short and long distances. We demonstrate that, once the form factor properties are correctly accounted for, the range of such an effective potential corresponds to the nuclear radius, removing any sensitivity to shorter-distance contributions. This potential changes sign over the atom's volume, so that the correction to the effective nuclear weak charge induced by this interaction is tiny and does not alter the interpretation of atomic parity violation experiments.
nucl-thhep-phnucl-exphysics.atom-ph1 citation
05
Emergence of Cluster Formation in Light Nuclei
José Nicolás Orce · Manfred Jason Jaftha
Spherical harmonics form a complete orthonormal basis which allows any function on the sphere to be expanded. The nuclear shape of a given eigenstate can thus be described within Bohr's quasi-molecular model by a coordinate transformation from a randomly oriented ellipsoid in space to a coordinate system aligned with the ellipsoid's principal axes. This transformation (Eq. 4) is characterized by three Euler angles and two deformation parameters, $β$ (quadrupole) and $γ$ (triaxiality), but does not uniquely define the nuclear shape; rotational averaging over equivalent orientations is expected to yield a diffuse nuclear shape. Rotational invariance under $β$ and $γ$ is achieved using three transformation operators, which define a new coordinate system aligned with a single intrinsic configuration (Eq. 6). Here we show that the non-unique coordinate system of Eq. 4 with $β$ and $γ$ deformation parameters extracted from experimental electric-quadrupole matrix elements actually yields the most probable nuclear shape. Only then does cluster formation spatially emerge in light nuclei and the characteristic bowling-pin-like shapes of $^{10}$ B and $^{20}$ Ne are reproduced, consistent with modern nuclear theory. Both coordinate systems generally exhibit the same shape features for heavier deformed nuclei, where substantial triaxial deformation is empirically observed. However, the approach based on Eq. 4, using empirical $β$ and $γ$ values, provides deeper insight by capturing the superposition of multiple intrinsic configurations that collectively form the nuclear state. This, in turn, offers a physical interpretation of triaxiality.
nucl-thnucl-ex0 citations
06
Study of jet-induced hydro response in high-energy heavy-ion collisions with a flow-matching generative model
Kai-Yi Wu🇨🇳 · Zhong Yang🇺🇸 · Long-Gang Pang🇨🇳 · Xin-Nian Wang🇨🇳
In high-energy heavy-ion collisions, propagation of the energy deposited into the medium by energetic partons that traverse the quark-gluon plasma (QGP) leads to Mach-cone-like jet-induced medium response. Event-by-event simulations of jet-induced medium responses within a complete model such as the coupled Linear Boltzmann Transport and hydrodynamic (CoLBT-hydro) model are very resource-intensive. In this study, we develop a flow matching generative model trained by CoLBT-hydro events for the study of the medium response induced by $γ$ -jets in high-energy heavy-ion collisions. With only the initial spatial and momentum information of the $γ$ and jets, the generative model is shown to conditionally reproduce the marginal final-state hadron spectra from the jet-induced hydro response in $0 - 10%$ Pb+Pb collisions at $s_{NN}$ = 5.02~TeV. The generative model achieves a computational acceleration of approximately six orders of magnitude compared to the full CoLBT-hydro simulations, while faithfully preserving the statistical properties of the front and the diffusion wake of the Mach-cone-like hydro response and their contributions to the hadron spectra. Hadron spectra from the medium response, correlations between the front and diffusion wake and rapidity asymmetry due to the diffusion wake in $γ$ -hadron correlation are further studied within the generative model.
nucl-thhep-ph1 citation
07
Sequential Bayesian inference with correlated heavy-ion datasets
Lipei Du
Bayesian inference provides a natural framework for updating knowledge as new information becomes available, often in a sequential manner by incorporating datasets in stages or reusing previous posteriors as priors. In practice, this is commonly implemented using a factorized update in which datasets are treated as conditionally independent. When datasets are statistically correlated, however, this approximation becomes inconsistent with the joint likelihood and can lead to biased posterior estimates. In this work, we investigate this issue in a controlled setting using pseudo-data with a tunable covariance structure. We compare joint inference, factorized sequential updating, and a formulation based on the exact conditional likelihood. We show that factorized updates reproduce the joint posterior only in the limit of conditional independence, and otherwise lead to systematic deviations that grow with the correlation strength, while conditional updates remain consistent with the joint result. To interpret these deviations, we introduce an information decomposition that separates contributions into components that are new and components that are redundant across datasets. We show that correlations induce a structured, parameter-dependent redistribution of information, governed by the overlap of dataset sensitivities. The resulting mismatch between marginal and conditional information quantitatively explains the observed deviations. These results provide a practical diagnostic for assessing the consistency of sequential Bayesian inference with correlated datasets and highlight the need for a consistent treatment of correlations within a common probabilistic framework.
nucl-thhep-phnucl-ex1 citation
08
Proton-to-Alpha branching ratio in the $^{12}$ C+ $^{12}$ C fusion reaction at astrophysical energies
Ruojun Yang · Ruiqi Chen · Xiao Fang · Yihua Fan · Xiaodong Tang · Yunju Li · Fengqiao Luo
The unique resonance features in the $^{12}$ C+ $^{12}$ C fusion reaction lead to significant fluctuations in the branching ratio $R_{p / α} = σ_{p} / σ_{α}$ , making it difficult to determine the $R_{p / α}$ at astrophysical energies. By combining Hauser--Feshbach statistical-model calculations with constraints from direct charged-particle and gamma-ray measurements, we investigate the energy dependence of the averaged $R_{p / α}$ and predict its behavior within the Gamow window. Owing to the strong energy dependence of $R_{p / α}$ , the corresponding reaction-rate ratios, $⟨ σ v ⟩_{p} / ⟨ σ v ⟩_{α}$ , during core and shell carbon burning are determined to be 0.29, 0.45, and 0.52 at $T_{9} = 0.5$ , 1.0, and 1.2, respectively, significantly lower than the widely adopted CF88 constant value of 0.79. The implications of the revised $⟨ σ v ⟩_{p} / ⟨ σ v ⟩_{α}$ ratio for stellar nucleosynthesis and white-dwarf evolution are also discussed.
nucl-thastro-ph.SRCPC(2026)·0 citations
09
Systematic study of one-point kinetic energy density functionals for atomic nuclei
Tian Shuai Shang · Jian Li · Haozhao Liang · Xinhui Wu · Cheng Ma · Wenhui Mi · Xuecheng Shao · Yanchao Wang
To explore the applicability of orbital-free density functional theory (OF-DFT) in nuclear physics, we perform a systematic benchmark of 36 one-point kinetic energy density functionals, which are originally developed for electron systems in condensed matter physics. It is found that the direct use of the original parameters for electron systems leads to inconsistent performance, with certain functionals exhibiting physically unacceptable asymptotic behaviors. However, through parameter re-optimization targeting nuclear densities, different mathematical forms of generalized gradient approximation (GGA) functionals converge to a consistent root-mean-square error of approximately 13 MeV. From a physical perspective, this consistent behavior signifies that the optimized semi-local GGAs have successfully captured the macroscopic, liquid-drop-like background of the nucleus, while the residual deviations appear as periodic oscillations at the magic numbers that could reflect the quantum shell effects.
nucl-thcond-mat.mtrl-sci0 citations
10
Astrophysics equation of state inference with Bayesian chiral effective field theory uncertainties
Melissa Mendes · Hannah Göttling · Anna Hensel · Isak Svensson · Kai Hebeler · Achim Schwenk · Nathan Rutherford · Anna Watts
We investigate Bayesian chiral effective field theory ( $χ$ EFT) uncertainties, which assign a statistical interpretation to equation of state (EOS) distributions near nuclear saturation density, n $_{0}$ , as well as constraints from perturbative quantum chromodynamics (pQCD) to Bayesian EOS inference from LIGO/Virgo, NICER and pulsar mass observations. The tails of the $χ$ EFT uncertainties allow for broader pressure ranges in our priors, but large parts of these are excluded by the astrophysical observations, so that the EOS and the resulting mass-radius posteriors are still very consistent with our earlier work. Within our broad prior ranges, we observe a clear stiffening of the EOS at $n ≳ 3 n_{0}$ . Moreover, the impact of the pQCD constraints on the posterior EOS and mass-radius range is negligible due to the astrophysics constraints. Exploiting the strong correlation between pure neutron matter and matter in beta equilibrium, we infer the symmetry energy slope parameter $L$ from astrophysics. For the $68%$ credible interval, we obtain $L = 42.6 - 52$ MeV and $L = 44.2 - 56.7$ MeV using piecewise-polytrope and speed-of-sound high-density extensions, respectively. The $L$ posterior is mainly driven by the combination of GW170817 LIGO/Virgo and PSR J0740+6620, PSR J0437-4715, and PSR J0614-3329 NICER observations.
nucl-thastro-ph.HE2 citations

Affiliations

first authorsco-authorsvia INSPIRE