PaperPanorama
FAQ

Nuclear Theory·nucl-th

Wednesday·August 5, 2026

13 papers—7 primary·6 cross-listed

All13Primary7Cross-lists6
  1. 01

    SU3HOB-cgvcs: harmonic-oscillator brackets in the SU(3) basis with isofactors from an external SU(3)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 . These brackets arte constructed in the basis by the method of Kalinauskas et al. . The transformation is reduced to a single sum over Wigner -functions of the reflection-containing Talmi--Moshinsky matrix weighted by products of isofactors of the chain . 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 representation analytically. The package reproduces, bracket for bracket to machine precision (), 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.

    nucl-thphysics.comp-ph0 citations
  2. 02

    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.

    nucl-th0 citations
  3. 03

    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.

    nucl-th0 citations
  4. 04

    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.

    nucl-th0 citations
  5. 05

    Finite-spectrum Lorentz integral transform calculation of the 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 He. A large set of eigenstates is explicitly calculated in the NCSM, and the LIT is constructed from their excitation energies and the corresponding 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 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 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.

    nucl-thnucl-ex0 citations
  6. 06

    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-O resonances.

    nucl-th0 citations
  7. 07

    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.

    nucl-thhep-ph0 citations

Affiliations

first authorsco-authorsvia INSPIRE