Nuclear Theory·nucl-th

Wednesday·August 5, 2026

13 papers—7 primary·6 cross-listed

01
[Submitted on 31 Jul 2026]
SU3HOB-cgvcs: harmonic-oscillator brackets in the SU(3) basis with isofactors from an external SU(3) $\supset$ SO(3) Clebsch--Gordan library
Augustinas Stepšys · Saulius Mickevičius · Darius Germanas
\DeclareRobustCommand{\Su}{\code{Su3cgvcs}} We present SU3HOB-cgvcs, a Fortran~2008 package that computes the general Talmi--Moshinsky harmonic-oscillator transformation brackets, for an arbitrary mass-ratio parameter $d$ . These brackets arte constructed in the $\su S U (3)$ basis by the method of Kalinauskas et al. . The transformation is reduced to a single sum over Wigner $d$ -functions of the reflection-containing Talmi--Moshinsky matrix weighted by products of $\su S U (3) \supset \su S O (3)$ isofactors of the chain $\su U (6) \supset \su U (3) \times \su U (2)$ . SU3HOB-cgvcs obtains these isofactors from the established external Clebsch--Gordan library \Su{} . In this library they are computed there by the vector-coherent-state (VCS) method. We bridge \Su{} formalism to ours and this requires two fixes: reinserting a sign/phase factor that depends on each state's radial-quantum number and handling the trivial $(0, 0)$ representation analytically. The package reproduces, bracket for bracket to machine precision ( $\sim 1 0^{- 13}$ ), the general Talmi--Moshinsky bracket code of Kamuntavičius et al. , and demonstrates that a self-contained SU(3)-scheme HOB code can be built on top of a general-purpose SU(3) Clebsch--Gordan library.
Comments:
Submitted to Computer Physics Communications
Subjects:
Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
2608.02640 [pdf]
0 citations
02
[Submitted on 4 Aug 2026]
Predominant Nuclear Excitation by Electron Capture Driven by Beam-Induced Return Currents
Y. Y. Xu · J. T. Qi · H. Peng · K. Jiang · R. Li · Q. Xiao · T. P. Yu · T. W. Huang
Predicted nearly five decades ago, nuclear excitation by electron capture (NEEC) remains experimentally elusive because its weak resonant signal is obscured by competing electron-driven excitation channels. Here we show that beam-induced surface return currents naturally overcome this limitation by creating a self-organized resonant electron source for the 8.36-eV nuclear transition in solid-density 229Th. A relativistic electron beam drives localized return currents along the solid surface, which simultaneously generate capture vacancies through impact ionization and provide resonant electrons for NEEC via a drifted Fermi distribution. Their spatial separation from the driving beam and the Pauli exclusion principle strongly suppress competing nuclear excitation by inelastic electron scattering. For experimentally available parameters, we predict 2.40*10^5 NEEC events with a NEEC fraction of 97.68%, and show that the excitation yield can be tuned over several orders of magnitude while preserving NEEC dominance. These results establish beam-induced return currents as a controllable route to resonant nuclear excitation in solids and open a new avenue for studying electron-driven nuclear processes.
Comments:
6 pages, 4 figures; Supplemental Material included: 8 pages, 4 figures, and 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.02998 [pdf]
0 citations
03
[Submitted on 4 Aug 2026]
Does strange meson condensation reduce the moment of inertia of massive proto neutron stars? insights at S = 1 and YL = 0.4
Nie-Cheng Jian🇨🇳 · Xian-Feng Zhao🇨🇳
We investigate the effects of strange mesons (sigma-star and phi) on the structural and rotational properties of massive proto neutron stars (PNSs) within the relativistic mean-field (RMF) framework. Using the TW99 parametrization with entropy per baryon S=1 and lepton fraction YL=0.4, we solve the TOV equations and compute the moment of inertia via the Hartle-Thorne approximation. Among eight parametrizations, TW99 is chosen as it gives the largest maximum mass. Our results show that strange mesons soften the equation of state at high densities, reducing both the maximum mass and radius. The moment of inertia peaks at a lower central density than the maximum mass, and strange mesons shift this peak toward higher densities while slightly lowering its value. The relative change in I is negligible for PNSs below 2.1 solar mass, but decreases to about -0.6 at 2.7 solar mass, indicating that strangeness effects are most relevant for the most massive stars. Our findings provide useful constraints on the rotational evolution of massive PNSs and their potential gravitational-wave signatures.
Comments:
8 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.03022 [pdf]
0 citations
04
[Submitted on 4 Aug 2026]
Microscopic Statistical Calculation of Nuclear Level Density Based on Relativistic Density Functional Theory
Zi-Cheng Wang · Peng-Xiang Du · Jian Li · T. M. Shneidman · Shan-Gui Zhou
A microscopic statistical model based on the relativistic density functional theory (RDFT) is developed to calculate the nuclear level density (NLD). The approach employs self-consistent single-particle levels obtained from RDFT as input, incorporates pairing correlations within a finite-temperature Bardeen-Cooper-Schrieffer (BCS) theory, and accounts for rotational and vibrational collective enhancement effects. The spin cut-off parameter is calculated from the single-particle levels, thereby naturally retaining the shell effects and the structural characteristics of different nuclei. Using the shape-coexisting nucleus 98Sr as a representative example, the microscopic origin of the deformation effect on the NLD is investigated. In addition, the calculated NLDs are systematically compared with those from various phenomenological and microscopic models, as well as with available experimental data. The results indicate that although certain discrepancies exist among different models, they exhibit consistent overall evolutionary trends. Meanwhile, the RDFT-based microscopic statistical approach is capable of providing a reasonable description of the experimental NLDs as well as the s- and p-wave neutron resonance spacings.
Comments:
13 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.03663 [pdf]
0 citations
05
[Submitted on 4 Aug 2026]
Finite-spectrum Lorentz integral transform calculation of the $^{4}$ He photoabsorption cross section in the no-core shell model
P. Yin · H. T. Zhao · C. Y. Zhai · J. P. Vary · H. Li · J. M. Dong · H. J. Ong · X. Zhao · P. J. Fasano · A. M. Shirokov · J. Chen · D. Y. Tao · B. Zhou · C. Ji
We develop and validate a finite-spectrum implementation of the Lorentz integral transform (LIT) within the \textit{ab initio} no-core shell model (NCSM) for calculating the photoabsorption cross section of $^{4}$ He. A large set of $1^{-}$ eigenstates is explicitly calculated in the NCSM, and the LIT is constructed from their excitation energies and the corresponding $E 1$ transition strengths. This finite-spectrum approach is complementary to conventional inhomogeneous-equation and Lanczos-based implementations of the LIT method for photoabsorption cross sections. Using the Daejeon16 interaction, we extract the photoabsorption cross section and examine its stability with respect to the model-space truncation, excitation-energy cutoff, and LIT parameters. The reliability of the finite-spectrum extraction is assessed by comparing the $E 1$ polarizability and bremsstrahlung sum rule obtained from the discrete NCSM spectrum with the same quantities obtained by integrating the extracted cross section. The extracted cross section captures the principal features of the available $^{4}$ He photonuclear data in the giant-dipole-resonance region and is consistent, in the low-energy rise and main-peak region, with earlier chiral-interaction NCSM-LIT results obtained from Lanczos-based evaluations, while the present calculation with the Daejeon16 interaction exhibits a more pronounced high-energy shoulder. The present work provides a controlled finite-spectrum NCSM-LIT route from explicitly calculated many-body eigenstates and transition strengths to photoabsorption cross sections.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2608.03686 [pdf]
0 citations
06
[Submitted on 4 Aug 2026]
Constructing Effective Interactions via Projection-Based Inversion
Hang Yu · Serdar Elhatisari · Sebastian König · Dean Lee · Yuan-Zhuo Ma · Takayuki Miyagi
We present a numerical prescription for extracting continuum scattering information from discrete spectra by constraining effective interactions inspired by effective field theory (EFT). Using a Multiparameter Eigenvalue Problem (MEP) emulator, we map energies to a sum of contact potentials by recasting the inverse problem as a linear eigenvalue equation. Because our method determines the effective interaction rather than the scattering amplitude, it can handle non-perturbative Coulomb interactions and different types of truncated Hilbert spaces without analytic quantization conditions. It therefore allows standard bound-state codes to be used for scattering calculations without modification. We validate this prescription across multiple ab initio frameworks using neutron-alpha scattering, alpha-alpha scattering with full Coulomb, and a prediction of proton- $^{14}$ O resonances.
Comments:
5 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2608.03748 [pdf]
0 citations
07
[Submitted on 4 Aug 2026]
Local Spin Polarization in Anisotropic Gubser Flow: Suppression Mechanism and Formulation Dependence
Kenji Fukushima🇯🇵 · Shi Pu🇨🇳 · Dong-Lin Wang🇯🇵
We analytically study the longitudinal spin polarization in relativistic heavy-ion collisions using a perturbed Gubser flow solution. In the large-system-size limit, we derive analytical expression of the local spin polarization along the beam direction. In our treatment, the contributions from thermal vorticity and thermal shear are of comparable magnitudes. The thermal vorticity yields the polarization with a sign opposite to that observed experimentally, while the thermal shear counteracts this effect, helping recover the desired sign. We find that the choice of the reference unit vector aligned with the fluid velocity gives the experimentally observed sign only at low transverse momenta, whereas another formulation with the unit vector fixed along the laboratory time direction yields the desired sign for a wide range of transverse momenta. Notably, a recent formulation with the unit vector normal to the freeze-out hypersurface exhibits an exact cancellation between contributions from thermal vorticity and thermal shear at leading order in the large-system-size limit. We identify a general cancellation pattern with acceleration dominance, which is manifest particularly in the latter two formulations. Thus, the total polarization originates from non-acceleration effects, which need not be substantial even when the elliptic flow is finite, as clearly demonstrated in our analytical results. For comparison, we also discuss the spin polarization in the Hubble flow with rotation.
Comments:
13 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2608.03945 [pdf]
0 citations
08
[Submitted on 3 Aug 2026] (cross-list from hep-lat)
The Momentum Fraction, Helicity and Transversity Isovector Moments of Nucleons from \texorpdfstring{ $2 + 1$ }{2+1}-flavor Lattice QCD
Santanu Mondal🇮🇳 · Rajan Gupta🇺🇸 · Sungwoo Park🇰🇷 · Jun-sik Yoo🇰🇷 · Tanmoy Bhattacharya🇺🇸 · Boram Yoon🇺🇸 · Bálint Joó🇺🇸 · Frank Winter🇺🇸
Results for the isovector momentum fraction, $⟨ x ⟩_{u - d}$ , helicity moment, $⟨ x ⟩_{Δ u - Δ d}$ , and the transversity moment, $⟨ x ⟩_{δ u - δ d}$ , of the nucleon are presented using high-statistics data on thirteen NME ensembles of gauge configurations generated by the JLab/W\&M/LANL/MIT/Marseille collaborations using $2 + 1$ -flavors of dynamical Wilson-clover quarks. The much higher statistics facilitated better control over all systematics compared to our previous lattice calculation. The least controlled systematic---excited-state contamination---is quantified by studying the variation of the results as a function of three estimates of the mass gap of the first excited state, obtained from two- and three-point correlation functions. The final results are obtained using a simultaneous fit to extrapolate in the lattice spacing, $a$ , pion and kaon masses, $M_{π}$ and $M_{K}$ , and the finite volume parameter, $M_{π} L$ . The data show no significant finite-volume correction, and some dependence on the lattice spacing and the renormalization factors. The largest systematic uncertainty is due to possible remaining excited states contributions. Our final results, in the $MS$ scheme at 2~GeV, are $⟨ x ⟩_{u - d} = 0.154 (10) (9)$ , $⟨ x ⟩_{Δ u - Δ d} = 0.177 (10) (15)$ and $⟨ x ⟩_{δ u - δ d} = 0.197 (12) (18)$ , where the first error is the overall statistical uncertainty and the second represents the various systematic uncertainties added in quadrature. Results for the momentum fraction and helicity moment are consistent with phenomenological global fit values, while the transversity moment is a prediction.
Comments:
41 pages, 13 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2608.02836 [pdf]
0 citations
09
[Submitted on 3 Aug 2026] (cross-list from quant-ph)
The Utility of Sparse Error Detection in Quantum Simulations
Henry Froland · Dorota M. Grabowska · Sebastian Grieninger · Jeremy Hartse · Anne L. Lashbrook · Zhiyao Li · Ziyuan Li · Sarah J. M. Powell · Martin J. Savage · Xiaojun Yao · Nikita A. Zemlevskiy
The recent success of error detecting codes points toward their potential application to fault-tolerant simulations of nature. In this work, we examine the utility of sparse error detection for simulating lattice gauge theories using quantum computers. In particular, we study the time evolution of the lattice Schwinger model embedded into the Iceberg code family, $[[N + 2, N, 2]]$ , as well as the Hypercube code family, $[[2^{N}, N, 2]]$ . The lattice of electrons and positrons in the axial gauge is embedded into a single code block or into multiple code blocks, and this work finds that large codeblocks are advantageous in the absence of connectivity constraints. Noisy classical simulations with realistic near-term error rates, infrequent syndrome measurements and physics-aware postselection are found to improve observable estimation. Under realistic noise rates for near-term quantum computers, this work finds that sparse error detection in quantum simulations has the potential to improve accuracy of observable estimation. Additional rounds of error detection are found to systematically drive errors in observables to the noise floor set by the code. These findings suggest that incorporating minimal implementations of fault tolerance in the near-term will enhance the performance of quantum simulations in nuclear physics and high-energy physics.
Comments:
32 pages, 37 figures, 4 tables, comments welcome
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2608.02944 [pdf]
1 citation
10
[Submitted on 4 Aug 2026] (cross-list from hep-ph)
Critical coupling with zero-mode corrections in discretized light-cone quantized $ϕ^{4}$ theory
Shreeram Jawadekar🇺🇸 · Mamoon A. Sharaf🇺🇸 · James P. Vary🇺🇸
We present an advancement for solving the Discretized Light-Cone Quantization (DLCQ) Hamiltonian for mass spectra in 2D $ϕ^{4}$ theory that incorporates perturbative zero-mode contributions. We demonstrate that this correction accelerates numerical convergence of the mass eigenstates with increasing resolution and yields a critical coupling of comparable accuracy with a substantial reduction in computational costs. Specifically, with more than one order of magnitude reduction in basis space dimensionality we achieve an extrapolated critical coupling of $23.10 \pm 0.25$ compared with $23.53 \pm 0.26$ in the larger basis but without zero-mode correction. We employ Gaussian Process Regression for extrapolation to the continuum limit. The approach we present here is prospective for studies of higher-dimensional gauge theories.
Comments:
10 pages, 4 figures, 4 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2608.02972 [pdf]
0 citations
11
[Submitted on 4 Aug 2026] (cross-list from hep-ph)
Faddeev equations for the $J / ψ N N$ and $ϕ N N$ three-body systems in momentum space
Xu Zhang🇨🇳
We construct Faddeev equations for the $J / ψ N N$ and $ϕ N N$ three-body systems in momentum space. The two-body subsystem $t$ -matrix is obtained by solving the Lippmann-Schwinger equations. The $N N$ interactions are constructed using the Malfliet-Tjon potential. The $J / ψ N$ interaction potentials in the $^{4} S_{3/2}$ and $^{2} S_{1/2}$ channels are taken from HAL QCD. The $ϕ N$ interaction potential in the $^{4} S_{3/2}$ channel is also taken from HAL QCD. The $^{2} S_{1/2}$ $ϕN$ interaction is obtained from the combination of the $ϕp$ correlation function analysis and the HAL QCD results, as well as from the assumption that the spin-spin parts of the $ϕN$ and $J / ψ N$ interactions are inversely proportional to the respective hadron masses. The Faddeev equations are solved to find bound states in the $J / ψ N N$ and $ϕ N N$ three-body systems. The numerical results suggest that there exist bound states in the $ϕ N N$ three-body system, while there is no bound state in the $J / ψ N N$ system.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2608.03162 [pdf]
0 citations
12
[Submitted on 4 Aug 2026] (cross-list from hep-ph)
On the nature of fully-charmed four-quark exotic state $X (6900)$ from its photoproduction off nuclei
E. Ya. Paryev
The possibility to study the nature of fully-charmed tetraquark state $X (6900)$ from its inclusive photoproduction off nuclei near the kinematic threshold is investigated within the collision model based on the nuclear spectral function. The model accounts for $X (6900)$ production in direct photon--nucleon interactions as well as three different scenarios for its internal structure: compact tetraquark, molecule of the two hidden-charm $J / ψ$ and $ψ (3770)$ mesons and the mixture of both of them. We calculate within these scenarios the absolute and relative excitation functions on $^{12}$ C and $^{184}$ W nuclei at near-threshold photon energies of 30--40 GeV, the absolute momentum differential cross sections and ratios of them for the $X (6900)$ meson production off these target nuclei at laboratory polar angles of 0 $^{\circ}$ --5 $^{\circ}$ and for photon energy of 35 GeV as well as the A-dependences of its transparency ratios at photon energy of 35 GeV. We show that these observables reveal a definite sensitivity to the $X (6900)$ intrinsic structure. Therefore, they might be useful for the determination of this structure from the comparison of them with the experimental data from the future experiments at the upcoming experimental facilities, such as the planned electron-ion colliders in the United States and China.
Comments:
21 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2608.03374 [pdf]
0 citations
13
[Submitted on 4 Aug 2026] (cross-list from nucl-ex)
Statistical and non-statistical $γ$ -decay properties of $^{64}$ Zn
A. C. Larsen · M. Guttormsen · T. K. Eriksen · G. M. Tveten · H. Utsunomiya · J. K. Dahl · N. Shimizu · T. Ari-izumi · F. L. Bello Garrote · L. T. Bell · M. M. Bjørøen · F. W. Furmyr and 14 other authors
We present a study on the $γ$ -decay properties of $^{64}$ Zn using the Oslo method on $^{64}$ Zn( $p, p^{'} γ$ ) data combined with $^{64}$ Zn $(γ, n)$ cross-section measurements at the NewSUBARU facility. With the Oslo method, we have measured the $γ$ -ray strength function ( $γ$ SF) and the nuclear level density (NLD) below the neutron threshold. We observe that the NLD trend in the quasi-continuum region of $^{64}$ Zn is best characterized by a constant-temperature-like model. %with temperature parameter $T_{CT} = 1.21 (5)$ MeV. Surprisingly, we find that $γ$ -ray transitions from the quasi-continuum decaying directly to the $0^{+}$ ground state seem to be strongly hindered with a hindrance factor of $κ \approx 0.5$ , which could be an indication of non-statistical effects in the ground-state decay due to, \textit{e.g.}, differences in nuclear shapes. For $γ$ energies above the neutron separation energy, the NewSUBARU ( $γ, n$ ) data set probes a significant part of the giant dipole resonance. Furthermore, we find that the Oslo-method $γ$ SF shows a rather smooth behavior, with a clear low-energy enhancement (LEE) for $E_{γ} < 4$ MeV.
Comments:
19 pages, 24 figures, submitted to Phys. Rev. C
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2608.03943 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE