Nuclear Theory·nucl-th

Mon·Sep 21, 2026Monday·September 21, 2026

9 papers—4 primary·5 cross-listed

01
Theoretical study of normal deformed rotational bands of odd-mass $^{167, 169, 171}$ Lu nuclei
Carlos E. Vargas · Víctor Velázquez-Aguilar · Jesús Ávila-Pulido
The theoretical description of nuclear structure in rare earth nuclei represents a significant challenge for many shell models. This difficulty stems from the size of the configuration space involved. Methods based on symmetries provide significant advantages. Furthermore, the pseudo-SU(3) shell model has proven to be very useful in the description of these systems. In particular, we propose to study the energy spectra of the rotational bands with normal deformation at low and medium spin ( $J \leq 35/2$ ), the quadrupole moments, and the deformation parameter $γ$ associated with the states, as well as the B(E2) transition strengths in the $^{167, 169, 171}$ Lu nuclei. The Hamiltonian includes $Q \cdot Q$ , Nilsson, and pairing terms, parameterized in a systematic way, in addition to three rotor-like terms that enable fine tuning of the spectra. Our calculations predict collective rotational bands with prolate normal deformation in most cases. The exception is the $1/ 2^{+}$ band in $^{171}$ Lu with a triaxial shape. The quadrupole moments vary along the bands, increasing in absolute value with spin. The $γ$ deformation parameter remains nearly constant along the bands, and the B(E2) values suggest bands with collective character and normal deformation. The agreement and limitations of the model are discussed.
nucl-thEur. Phys. J. A (2025) 61:256
02
Microscopic analysis of M1 scissors mode in $^{254}$ No
V.O. Nesterenko · M.A. Mardyban · A. Repko
The low-energy $M 1$ orbital scissors mode (SM) was recently observed by Oslo group in deformed nucleus $^{254}$ No. This is the heaviest nucleus where SM was ever experimentally found. We propose the analysis of SM, together with the spin-flip $M 1$ resonance, within fully self-consistent Quasiparticle Random-Phase Approximation (QRPA) with Skyrme forces SG2, SLy4 and SLy5. The impact of "tensor" $J^{2}$ -term, introduced by perturbative (on the base of SG2) and consistent (SLy5) ways, is analyzed and shown to be noticeable but not decisive. The deformation-induced coupling of $M 1$ and $E 2$ states is inspected. The calculations reasonably describe Oslo's experimental data. The best agreement is obtained for SLy5. A fine structure of SM in $^{254}$ No is predicted. A significant constructive interference of the dominant orbital and minor spin-flip contributions to $M 1$ strength at SM energy region is found. What is remarkable, our analysis of distributions of the convective nuclear currents challenges the scissors-like flow usually assumed for SM.
nucl-th
03
Systematic Study of Proton, Two-Proton, Alpha, and Cluster Radioactivity Half-Lives based on the Deformed Gamow-like Model and Tabular Prior-data Fitted Network ( $TabPFN$ )
Anqi Yang · Panpan Qi · Qingning Yuan · Gongming Yu · Haitao Yang · Zhangyan Li · Yanbing Cai
A hybrid framework combining the deformed Gamow-like model ( $DGLM$ ) with the Tabular Prior-data Fitted Network ( $TabPFN$ ) is developed to improve half-life predictions for two-proton emission, proton emission, $α$ decay, and cluster radioactivity. A total of 583 radioactive nuclei are investigated, including 17 two-proton emitters, 42 proton emitters, 498 $α$ emitters, and 26 cluster emitters. Among the four considered models, $DGLM^{b} + TabPFN$ achieves the best overall performance, with $σ_{RMS} = 0.423$ , corresponding to an improvement of approximately $82.2%$ over $DGLM^{b}$ . The model parameters are optimized for each decay mode using the least-squares method. After introducing $TabPFN$ , the prediction errors for proton emission and $α$ decay are reduced by approximately $80.6%$ and $87.6%$ , respectively. For $α$ decay, the training, test, and overall RMSEs are 0.208, 0.305, and 0.240, indicating good generalization capability without evident overfitting. The model also reproduces the systematic evolution of $α$ -decay half-lives and the shell-closure effect around $N = 126$ . These results demonstrate that combining $DGLM$ with $TabPFN$ significantly improves the accuracy and robustness of radioactive-decay half-life predictions while retaining the physical interpretability of the original model.
nucl-th
04
Axial $U (1)$ Symmetry Breaking in Hot QCD: From Topology to the Chiral Phase Transition
Heng-Tong Ding
Heating matter can restore symmetries spontaneously broken at low temperature. The axial $U (1)$ symmetry of quantum chromodynamics (QCD) is different: it is present in the classical theory with massless quarks but is broken upon quantization by the axial anomaly. The anomaly persists at every temperature, yet its observable effects can weaken. Can hot matter nevertheless behave as though this symmetry were restored at long distances? Whether such effective axial $U (1)$ restoration occurs depends on how microscopic quark and gluon dynamics governs the strength and spatial range of axial breaking. This review brings together theoretical developments and first-principles lattice QCD calculations. We examine how gluon-field topology shapes the low-lying Dirac modes and their correlations, how these modes contribute to axial breaking at different spatial scales, and what this implies for the order and critical behavior of the chiral phase transition as quark masses approach zero.
nucl-thhep-lathep-phhep-th
05
Interacting Boson System at Finite Temperature: The treatment of the lattice calculations
D. Anchishkin · V. Gnatovskyy · D. Zhuravel · V. Karpenko
We study interacting relativistic charged bosons at finite temperature and isospin density in a thermodynamically consistent mean-field approach with repulsive phi-4 and phi-6 interactions. The thermodynamics is formulated in an Extended Canonical Ensemble, in which the conserved isospin density, not the chemical potential, is the independent variable. This is essential in the condensed phase, where mu_I is fixed by condensation. With one constant fitted to the lattice pressure at T=122 MeV, the model reproduces the lattice isospin density, energy density, and trace anomaly, phi-6 being more accurate.
↳ hep-phhep-latnucl-th
06
Jet transport coefficients associated with fermionic two-point correlators in a weakly-coupled plasma
Shay Duddy · Lukas Opitz · Amit Kumar · Gojko Vujanovic
A new set of jet-medium transport coefficients stemming from jet-medium exchanges involving Glauber quarks encoded in $F^_{i}$ [Phys. Rev. C 111, 054913 (2025), Phys. Rev. C 113, 055207] are obtained by computing the tree-level leading-order $2 \to 2$ scattering rates and their moments using the approach developed in Refs. [arxiv 2608.17160, arxiv 2608.17161]. Sizeable deviations away from the leading logarithmic dependence of jet-medium transport coefficients and scattering rate are observed here, as previously mentioned in Refs.[arxiv 2608.17160, arxiv 2608.17161]. A closed-form expression for $F^_{i}$ accurate to $≲ 10$ \% or better is obtained, enabling our approach to be used within Monte Carlo simulations of jet-medium interactions. Monte Carlo simulations incorporating $F^_{i}$ are sensitive to flavor hydrodynamization dynamics as the medium created in nucleus-nucleus collisions transitions from the early-time Glasma dynamics to the quark-gluon plasma fluid.
↳ hep-phnucl-exnucl-th
07
Sine-Gordon Model with Bosonic Tensor Networks: Continuum Matching and Soliton Scattering
Florian Hechenberger · Tommaso Rainaldi · Felix Ringer
We use bosonic tensor networks to connect the lattice sine-Gordon model in the Hamiltonian formulation quantitatively to its continuum theory. Matching the lattice vertex operator to its conformal normalization at the free-boson ultraviolet fixed point yields the exact relation between the bare lattice coupling and the renormalized continuum mass parameter. The soliton mass then approaches Zamolodchikov's exact continuum prediction throughout the studied parameter range, without adjustable parameters. Using uniform matrix product states and a quasiparticle ansatz, we also recover the relativistic soliton dispersion and the two lightest breather masses at the percent level. We simulate real-time collisions of Gaussian soliton-antisoliton wave packets near a reflectionless point and extract the Wigner spatial displacement. We compare this displacement with the exact continuum prediction obtained from the momentum derivative of the transmission phase, recovering its characteristic rapidity dependence. Our bosonic simulations provide a foundation for nonintegrable extensions, offer lessons for renormalization in other Hamiltonian lattice field theories, including gauge theories, and provide benchmarks for continuous-variable quantum simulations.
↳ quant-phhep-phhep-thnucl-th
08
Structure and astrophysical properties of dark energy admixed neutron stars
Juan M. Z. Pretel · Sergio B. Duarte · Mariana Dutra · Odilon Lourenço
The presence of a dark energy (DE) core, made of a Chaplygin dark fluid, is capable of influencing the diverse observable properties of neutron stars (NSs). However, there is also the possibility that NSs could contain a mixture of ordinary nuclear matter and DE. In this perspective, we propose an equation of state (EoS) that includes both normal matter and DE, where a free parameter $f$ quantifies the ratio of DE density with respect to the total energy density. As expected, in the limit $f \to 0$ we recover the already known results corresponding to pure nuclear matter. Remarkably, increasing this fraction $f$ leads to a softer EoS and thus strongly favors the fulfillment of the causality condition. As a consequence of our mass--radius results, the central compact object in HESS J1731-347 can be satisfactorily described as a DE admixed NS. For sufficiently high stellar masses, our calculations further indicate that both the gravitational redshift and the fundamental nonradial oscillation frequency increase significantly with an increasing DE fraction, whereas the opposite trend is observed for the total gravitational mass and tidal deformability. As is typical for compact stars composed purely of ordinary matter, we find that in our DE admixed stellar models the central density corresponding to the maximum-mass configuration coincides with the point at which the squared radial vibration frequency vanishes. Moreover, higher DE concentrations lead to enhanced stability of these configurations.
↳ gr-qcastro-ph.HEnucl-th
09
Nonlinearly Causal General-Relativistic Two-Fluid Dissipative Magnetohydrodynamics
Elias R. Most · Samuel J. Dunham
We present a formulation of general-relativistic (GR) 19-moment dissipative magnetohydrodynamics (MHD), capable of handling all first-order dissipative terms (viscosity, heat conductivity, resistivity and Hall terms), as well as all ideal electron degrees of freedom (number density, momentum and energy) in a GR astrophysical two-fluid plasma. We derive necessary and sufficient nonlinear causality conditions for the constrained first-order 19-moment system, as well as both necessary and sufficient conditions for strong hyperbolicity. To assess the formulation numerically, we develop a high-resolution shock-capturing scheme that solves these equations in a performance-portable fashion. The scheme expresses all evolution equations, including the dissipative and electron sectors, in flux-divergence form, allowing us to model systems with scales separated by orders of magnitude without resolving kinetic scales everywhere on the grid. In addition, we use implicit integration methods to systematically overstep kinetic scales in MHD regions, such as cyclotron and plasma frequencies. To make the scheme as robust as GRMHD codes, we construct necessary and sufficient conditions for a conserved state to be physically admissible, and based on these construct a new physicality-enforcement scheme. As an exact validation comparison, we formulate and derive a full solution to dissipative two-fluid Bondi accretion in general relativity. We then validate the equations against a series of results from kinetic particle-in-cell models of black hole accretion and magnetospheric dynamics, demonstrating that our formulation and scheme can correctly capture major features relevant for feedback on global scales of these solutions, including dimensionless reconnection rates of order $0.1$ and Braginskii-like anisotropic pressures and heat fluxes.
↳ astro-ph.HEastro-ph.IMgr-qcnucl-th+1