Nuclear Theory·nucl-th

Tuesday·August 11, 2026

12 papers—7 primary·5 cross-listed

01
[Submitted on 8 Aug 2026]
On three-cluster resonance structure of hypernuclei $_{Λ}^{7}$ He, $_{Λ}^{7}$ Li and $_{Λ}^{7}$ Be
N. K. Kalzhigitov · S. Amangeldinova · V. O. Kurmangaliyeva · V. S. Vasilevsky
The bound and resonance states of hypernuclei $_{Λ}^{7}$ He, $_{Λ}^{7}$ Li and $_{Λ}^{7}$ Be are studied within a three-cluster model. Within this model, hypernuclei $_{Λ}^{7}$ He, $_{Λ}^{7}$ Li and $_{Λ}^{7}$ Be are considered as three-cluster systems $^{4}$ He+ $^{2} n$ + $Λ$ , $^{4}$ He+ $d$ + $Λ$ , $^{4}$ He+ $^{2} p$ + $Λ$ , respectively. Special attention is paid to determining resonance states in the three-cluster continuum of these hypernuclei and to study their nature. One semi-realistic nucleon-nucleon potential is employed to determine the internal structure of the clusters $^{4}$ He, $^{2} n$ , $d$ and $^{2} p$ , and their interaction. Three versions of the nucleon-hyperon potential, known as the YNG potential, are employed to determine the interaction of the listed clusters with the lambda hyperon. A set of very narrow and fairly wide resonance states is found in the three-cluster continuum of $_{Λ}^{7}$ He, $_{Λ}^{7}$ Li and $_{Λ}^{7}$ Be. The narrowest resonance states were detected in $_{Λ}^{7}$ He and $_{Λ}^{7}$ Li and their total width does not exceed 10 keV. The dominant decay channels of these resonance states are revealed.
Comments:
53 pages, 21 figures, 16 tables, typos corrected
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.07930 [pdf]
0 citations
02
[Submitted on 9 Aug 2026]
White dwarf-neutron star matter transition and the effect of light elements
Yao Ma · Yong-Liang Ma · Ruo-Xi Wu · Yue-Liang Wu
White dwarfs and neutron stars are unique laboratories for dense nuclear matter physics. We develop a single relativistic mean-field framework that treats both classes of compact star, and the transition between them, on the same footing: the nuclei of white-dwarf matter are solved self-consistently as Wigner-Seitz cells with the full electromagnetic interaction, while the same Lagrangian yields the uniform nuclear matter of the neutron-star interior. Within this unified description we compute light-element white dwarfs seeded by $^{4}$ He, $^{12}$ C, and $^{16}$ O, following each fixed- $A$ sequence along its neutronization path and connecting it to the neutron-star branch through exact Maxwell junctions, from which the corresponding mass-radius relations are derived. The helium- and carbon-seeded white-dwarf sequences attain maximum masses of $\sim 1.4 M_{⊙}$ and $\sim 1.0 M_{⊙}$ , respectively. On the neutron-star branch, the retained light-element envelope changes the predicted radii only at the percent level---by approximately $0.2$ km at $1.4 M_{⊙}$ , within current observational uncertainties. Providing a consistent zero-temperature equation of state from white-dwarf to neutron-star densities, this unified framework offers a natural starting point for studies of white-dwarf--neutron-star binary mergers, progenitor-star evolution, decihertz gravitational-wave sources, and related multimessenger phenomena.
Comments:
13 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.08824 [pdf]
0 citations
03
[Submitted on 9 Aug 2026]
Large Amplitude Collective Motion and Dissipation in the Ground State and the First Isomeric Wells in the Neutron-Induced Fission of $^{235}$ U
Ibrahim Abdurrahman · Matthew Kafker · Aurel Bulgac · Ionel Stetcu
In fission induced by low energy neutrons, the mother nucleus spends a significant fraction of the time in the ground state and isomer wells, eventually passing beyond the outer barrier, where the primary fission fragments properties are defined. Despite this, the dynamics of these two early stages have not been investigated using microscopic models. This study examines the evolution of the mother nucleus in both wells separately, using time-dependent density functional theory, which has been previously used to treat the saddle-to-scission stage of fission for $^{235}$ U(n,f) reactions. These two early stages of fission are essential blocks in the final theory of the formation and evolution of a compound nucleus. The present study shows that the dynamics in both wells is strongly dissipative, similar to the dynamics from saddle to scission. It also reveals that while the initial mass asymmetry of the system quickly settles to very small fluctuations in the ground state well, in the isomeric well, the mass asymmetry oscillates with a rather large amplitude, in almost harmonic motion. Furthermore, with low probability, neutrons are emitted in both wells.
Comments:
5 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.08875 [pdf]
1 citation
04
[Submitted on 10 Aug 2026]
Hadron-quark phase transitions along proto-neutron-star evolution
P. Laskos-Patkos🇬🇷 · P.S. Koliogiannis🇭🇷 · Ch.C. Moustakidis🇬🇷
The new era of multi-messenger astronomy requires the accurate and self-consistent derivation of the nuclear equation of state at high temperature. In the present work, we focused on the calculation of hot hybrid equations of state, studying the different evolution stages of a proto-neutron star with a quark matter core (proto-hybrid star). For the hadronic matter we used two distinct Skyrme effective interactions, while for quark matter the well-known vector MIT bag model was employed. To model the era of trapped neutrinos in the system we considered the global conservation of lepton fraction which resulted in an equation of state with an extended mixed phase. For periods following the neutrino diffusion phase of a proto-neutron star, the equations of state were modelled using both the Maxwell and the Gibbs construction depending on the assumption for either local or global electric-charge conservation. With the use of the derived hybrid models, we solved the Tolman-Oppenheimer-Volkov equations to describe the corresponding hybrid star configurations. Finally, we investigated how the structure of proto-hybrid stars evolves, using constant rest mass sequences. We found that regardless of whether electric-charge is globally or locally conserved, the earlier stages of a hybrid star's life may play a crucial role on the determination of its maximum possible gravitational mass in later stages.
Comments:
v1: 17 pages, 6 figures, 1 table
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
2608.09195 [pdf]
0 citations
05
[Submitted on 10 Aug 2026]
Long-lived opposite-parity states and the onset of octupole collectivity in atomic nuclei
Bui Minh Loc · Hoang Thai An · Nguyen Le Anh · Panagiota Papakonstantinou · Naftali Auerbach
Octupole deformation in atomic nuclei is of interest for both nuclear structure and precision tests of fundamental symmetries, but identifying regions of octupole collectivity remains challenging. We analyze low-energy spectra of odd-mass nuclei and uncover a previously unrecognized empirical regularity that serves as a signature of octupole collectivity in neighboring even-even systems. The observed patterns, which can be understood within a core-coupling picture, are consistent with previous theoretical studies and lead to predictions for neutron-rich and proton-deficient nuclei. These findings provide a simple empirical guide for identifying promising candidates for future experiments and microscopic calculations.
Comments:
6 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2608.09386 [pdf]
0 citations
06
[Submitted on 10 Aug 2026]
Neutron radii and semi-phenomenological treatment of neutron distributions for Mg isotopes
Govind Kumar · M. Imran · Z. Hasan · Z. A. Khan
Involving the charge radii of \rm Mg isotopes, as calculated using the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc), we have extracted the neutron radii of $^{24 - 38}$ \rm Mg isotopes by studying their reaction cross sections ( $σ_{R}$ ) from $^{12}$ \rm C at 240 MeV/nucleon within the framework of Glauber model. The calculations use (i) descriptions of nuclei in terms of the Slater determinant involving harmonic oscillator single-particle wave functions (SDHO), and (ii) two-parameter Fermi (2pF) shape of density distribution, with the aim to assess the density dependence of neutron skin in $^{24 - 38}$ \rm Mg isotopes. To understand the asymptotic behavior (spread) of neutron distribution, we propose to introduce the use of core+n ( $S_{n} < S_{2 n}$ ) or core+2n ( $S_{n} > S_{2 n}$ ) description for stable as well as unstable isotopes; $S_{n}$ ( $S_{2 n}$ ) is the one-neutron (two-neutron) separation energy of the considered isotope. The core+n (core+2n) is treated semi-phenomenologically. In this work, the core+n is employed for $^{25 - 38}$ \rm Mg isotopes, and is subjected to reproduce the same neutron radius of the given isotope, as we obtained from $σ_{R}$ calculations. To validate the core+n description, we have revisited the reaction cross sections of $^{25 - 38}$ \rm Mg isotopes. The results are found to agree well with the experimental values. Moreover, the core+n neutron distributions clearly demonstrate the one-neutron halo structure of $^{37}$ \rm Mg. These findings motivated us to use the core+2n description for the neutron distribution of $^{40}$ \rm Mg in predicting its neutron radius, and $σ_{R}$ from $^{12}$ \rm C at 240 and 1000 MeV/nucleon. The trend of the neutron radius and $σ_{R}$ suggests that $^{40}$ \rm Mg exhibits two-neutron halo like structure.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.09429 [pdf]
0 citations
07
[Submitted on 10 Aug 2026]
A Gaussian Process framework for constraining the nuclear equation of state from microscopic calculations with correlated uncertainties
Y. G. Lee · J. Kim · T. Zhao · C. Drischler
We present constraints on the nuclear equation of state (EOS) from microscopic asymmetric matter calculations at zero temperature based on chiral nucleon-nucleon and three-nucleon interactions. The constraints include the saturation point, the isospin dependence of the incompressibility, and the symmetry energy, as well as the crust-core transition density of neutron-star matter. To quantify and propagate correlated uncertainties from noisy many-body calculations to derived observables, we introduce GPDiff, an efficient JAX-based Python package for multivariate Gaussian process (GP) regression with automatic differentiation. After training, GPDiff enables joint predictions of the EOS and derivatives of arbitrary order with respect to the input variables, including mixed partial derivatives. In this initial application, we analyze recent high-order many-body perturbation theory calculations of asymmetric matter up to about twice saturation density and explore nonstationary change-surface kernels, a class of input-dependent kernels, for modeling the EOS. GPDiff is broadly applicable to microscopic nuclear EOS calculations at zero and finite temperature and provides a versatile package for GP-based uncertainty quantification and inference of the nuclear EOS.
Comments:
30 pages, 13 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2608.09678 [pdf]
0 citations
08
[Submitted on 7 Aug 2026] (cross-list from hep-ph)
Quest for an Understanding of Pion and Kaon Structure
Zhen-Ni Xu🇪🇸 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳 · José Rodríguez-Quintero🇪🇸
The emergence of massless (Nambu-Goldstone) bosons in association with a dynamically global broken symmetry is a long known and widespread phenomenon in physics. However, practically nothing is known about the expressions of Nambu--Goldstone boson character on the internal structure of these bound states. Indeed, their structure is often ignored. In strong interactions, pions and kaons are the (would-be) Nambu-Goldstone bosons and experiments underway or planned at existing or anticipated high-energy, high-luminosity facilities will gather data that it is hoped will enable maps to be drawn of their internal structure. Meanwhile, theory and phenomenology find themselves in something of a quagmire. Herein, we provide a snapshot of the current status, highlighting issues under debate and identifying areas that deserve greater attention so that best use can be made of what is likely to be a huge volume of data delivered in the next decade or so.
Comments:
13 pages, 7 figures, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2608.07670 [pdf]
0 citations
09
[Submitted on 7 Aug 2026] (cross-list from astro-ph.HE)
Fast and Accurate Prediction of Neutron Star Structure with Deep Neural Networks
Kaushikk V N · Bhaskar Biswas · Stephan Rosswog
Solving the Tolman--Oppenheimer--Volkoff (TOV) equations, together with the tidal perturbation equations, for large numbers of equation-of-state (EOS) samples is a major computational bottleneck in Bayesian inference of the dense-matter EOS, and this will become increasingly limiting as next-generation observatories deliver far larger and more precise datasets. We develop neural-network surrogates for the forward TOV mapping that predict neutron star mass, radius, and tidal deformability simultaneously and directly from the EOS parameters and central density. We train and compare two architectures: a conventional feedforward network and a residual network, the latter of which, to our knowledge, has not previously been explored for TOV surrogate modeling. Trained on a piecewise polytropic EOS parameter space, both networks reproduce the numerical solutions to high accuracy, with the coefficient of determination exceeding 0.999 for all three observables, while accelerating the evaluation of stellar observables by roughly two orders of magnitude relative to direct numerical integration. We find that both architectures achieve excellent predictive accuracy at the network sizes considered here, with the residual network providing a modest improvement in accuracy over the feedforward network at the expense of slightly longer inference times. The overall performance differences remain small, indicating that a feedforward network already has sufficient capacity for this mapping while residual connections offer only incremental gains. Nevertheless, the residual architecture provides a robust baseline for future extensions to richer EOS parameterizations or higher-dimensional regression tasks. The resulting surrogates are well-suited to large-scale Bayesian EOS inference and population studies, where repeated TOV evaluations would otherwise dominate the computational cost.
Comments:
13 pages, 11 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2608.07698 [pdf]
0 citations
10
[Submitted on 8 Aug 2026] (cross-list from quant-ph)
Hamiltonian spectra in quantum computers through the generalized eigenvalue method
Valery Simonyan🇺🇸 · Greg Ridgway · Paulo Bedaque🇺🇸
Quantum computers can generate real-time correlators of field theories. By adapting the generalized eigenvalue problem to these correlators, energy eigenvalues can be extracted directly. The method is tested using both classical simulations and quantum hardware, successfully resolving several low-lying energy levels in agreement with exact diagonalization. Comparison with an alternative spectrum determination based on the Fourier transform of correlators shows that the proposed approach is substantially more efficient.
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2608.08181 [pdf]
0 citations
11
[Submitted on 9 Aug 2026] (cross-list from hep-ph)
Improved Regge Kinematics and All-Path-Length Corrections to Momentum Broadening in the Quark-Gluon Plasma
Dario van den Berg🇿🇦 · Isobel Kolbe🇿🇦
We present a study of transverse momentum broadening for high-energy partons propagating through the quark-gluon plasma (QGP), extending the Gyulassy-Levai-Vitev (GLV) formalism to include both all-path-length (APL) corrections and improved sub-Regge kinematics. The standard GLV framework relies on the large separation distance and large formation time approximations, which are well justified in large nuclei but may become unreliable in small collision systems, where the relevant length and coherence scales are comparable. Working to first order in the opacity expansion, we derive analytic expressions for the transverse momentum broadening distribution and the corresponding momentum transport coefficient, $q^$ , while systematically relaxing these approximations. The APL correction arises from relaxing the large separation distance approximation, whereas the sub-Regge and combined sub-Regge-APL corrections are obtained using an improved set of Regge kinematics beyond the strict Regge limit. We find that these corrections can substantially modify both the transverse momentum broadening distribution and the momentum transport coefficient, particularly for short path lengths and high exchanged momentum, providing a more complete theoretical description of momentum broadening in the QGP.
Comments:
6 pages, 2 figures. Contribution to the 70th Annual Conference of the South African Institute of Physics (SAIP2026), 6-10 July 2026
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2608.08894 [pdf]
0 citations
12
[Submitted on 10 Aug 2026] (cross-list from hep-ph)
Prospects for early heavy-quark measurements at the EIC
Allencris John Rubesh Rajan · Laboni Manna
We assess the prospects for inclusive heavy-quark-pair electroproduction in electron-proton ( $e p$ ) and electron-nucleus ( $e$ A) collisions, alongside double-charm-pair ( $D^{0} D ˉ^{0}$ and $D^{0} D^{0}$ ) electroproduction in $e p$ collisions, during the early operational phase of the Electron-Ion Collider (EIC). Based on the anticipated beam energies and luminosities of the EIC, we estimate the total cross sections and differential distributions for photon virtuality $Q^{2}$ , heavy-quark transverse momentum, and rapidity. This analysis evaluates different Bjorken- $x$ ( $x_{Bj}$ ) intervals across a range of $Q^{2}$ values. Expected event yields are estimated from the projected integrated luminosities of the early science programme, demonstrating the substantial improvement in statistical precision over previous HERA measurements at moderate and large $x_{Bj}$ . For electron--nucleus collisions, we compute the nuclear modification ratio $R^{e A}$ within collinear factorisation using nuclear parton distribution functions, and identify the kinematic regimes in which shadowing, anti-shadowing, and EMC-like suppression are accessible with early EIC data. These results are intended to serve as a parton-level baseline to support feasibility studies and to provide a reference for future higher-order theoretical and experimental investigations at the EIC.
Comments:
13 pages, 17 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2608.09608 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE