Nuclear Theory·nucl-th

Tuesday·July 7, 2026

19 papers—11 primary·8 cross-listed

01
Relativistic Vorticity in the Quark-Gluon Plasma: Generation Symmetries, Explosive Dilution, and Azimuthal Spin Alignment
Malak Ait Tamlihat (Mohammed V University)🇲🇦 · Ghizlane Ez-Zobayr (Mohammed VI Polytechnic University)🇲🇦 · Laurent Schoeffel (CEA)🇫🇷 · Yahya Tayalati (Mohammed V University, Mohammed VI Polytechnic University)🇲🇦
This article provides a self-contained bridge between classical vortex dynamics and the relativistic, subatomic domain of the Quark-Gluon Plasma (QGP) produced in ultra-relativistic heavy-ion collisions. While the QGP is widely studied for its near-perfect fluidity, we focus on its role as the most vortical medium in the Universe ( $ω \sim 1 0^{22} s^{- 1}$ ). The originality of our approach lies in isolating the explicit physical competition between non-linear vortex stretching and violent relativistic volumetric dilatation. By solving the covariant transport equations and tracking the comoving enstrophy density, we demonstrate that the explosive kinematics of the QGP provide an innate geometric shield that naturally regularizes the continuous flow, suppressing the self-amplification of vortex tubes before any microscopic viscosity is required. Furthermore, we connect this expansion phase back to the highly non-equilibrium initial state. We quantitatively predict that under a peripheral dipole initial topology, the global mid-rapidity hyperon polarization vanishes ( $P_{Λ} ≲ 1 0^{- 4}$ ), establishing that the definitive signature of the QGP's rotation must be sought in azimuthal differential measurements within the LHC and RHIC experimental programs.
nucl-thhep-ph0 citations
02
Circle of Alpha-Particle Cluster Shapes in Neon-20
N.S. Manton
Quantum states of Neon-20 are generally agreed to lie in rotational-vibrational bands of a cluster of five alpha particles. However, more than one cluster shape has been proposed as dominant at low energy. As relative motion within a cluster is soft in certain directions, we investigate how the low-lying rotational bands of Neon-20 can arise from a circle of clusters connecting favoured shapes: a triangular bipyramid, a square pyramid, and a $D_{2 d}$ -symmetric distorted tetrahedron -- a twisted bow-tie. Motion around the circle extends the Berry pseudo-rotation that connects differently oriented bipyramids.
nucl-thcond-mat.mtrl-scihep-th0 citations
03
Global systematics and theoretical interpretation of $l$ -forbidden $M 1$ transitions in odd- $A$ nuclei
Yu-kun Li · Guang-xin Zhang · Chong Qi
The $l$ -forbidden magnetic dipole ( $M 1$ ) transitions, characterized by a change in orbital angular momentum ( $Δ ℓ = 2$ ), serve as sensitive probes of higher-order effects, including configuration mixing and meson-exchange currents. In this work, we present a comprehensive systematic study of all experimentally known $l$ -forbidden $M 1$ transitions, covering odd- $A$ nuclei with neutron numbers $27 \leq N \leq 126$ . To interpret these global systematics, we apply a theoretical framework based on the relativistic Dirac wave function. This approach directly links the $l$ -forbidden $M 1$ transition amplitudes between pseudospin-partner orbitals to experimental single-particle magnetic moments. We perform a global comparison across isotopic chains by substituting unknown magnetic moments with rescaled Schmidt estimates. Focusing on dominant transition groups, including $p_{3/2} \to f_{5/2}$ , $s_{1/2} \to d_{3/2}$ , and $d_{5/2} \to g_{7/2}$ , our analysis establishes a robust linear correlation between the transition amplitudes $B (M 1)$ and the corresponding empirical single-particle matrix elements $M_{sp}$ . The proportionality coefficient $ρ$ serves as an empirical measure of single-particle strength fragmentation and quantifies the role of configuration mixing in driving $l$ -forbidden transitions across the nuclear chart.
nucl-th0 citations
04
Evaluation of U-235 and U-238 Fission Product Yields Using Bayesian Neural Networks: Comparison of Baseline and Physics-Informed Models
Chun-Yuan Qiao · Ya-Xuan Wang · Jun-Chen Pei · Chun-Wang Ma · Yong-Jing Chen · Jin-Gen Chen · Jie Pu · Kai-Xuan Cheng · Yu-Ting Wang · Ya-Fei Guo · Xiang Chen
U-235 and U-238 are fundamental materials in thermal and fast neutron breeding studies. Accurate evaluation of their fission product yields is of critical importance for advanced reactor design and nuclear waste management. In this work, a baseline Bayesian neural network model (BNN0) with two hidden layers of 20 neurons each was constructed. An improved model, BNN3, was developed by incorporating additional physics-informed features, namely the odd-even effect, beta-decay energy, and isospin, into the network inputs. Comparative analyses of the general distributions of the fission yields and isotopic chain structures demonstrate that BNN3 exhibits significantly improved reconstruction accuracy and consistency with the target cumulative fission-yield distributions. For 16 representative fission products, the energy-dependent yield predictions of BNN3 show better agreement with both experimental data and evaluated libraries, accompanied by noticeably narrower confidence intervals. These results indicate that the incorporation of relevant physical information improves the model's sensitivity to underlying fission mechanisms and enhances its capability to reproduce the systematic characteristics of cumulative fission-yield distributions. Together, these strategies contribute to more accurate and robust nuclear data modeling, providing a methodological foundation for the evaluation and development of next-generation nuclear data libraries.
nucl-thFront.Phys.(Beijing)(2027)·0 citations
05
An expanding spherical fireball model for light hadron production at RHIC ( $s_{NN} = 7.7$ -- $39$ GeV)
Ashutosh Dwibedi🇮🇳 · Anupam Panja🇮🇳 · Sabyasachi Ghosh🇮🇳
We investigate the transverse momentum ( $p_{T}$ ) spectra and rapidity distributions of the light hadrons $π^{\pm}$ , $K^{\pm}$ , $p$ , and $p ˉ$ produced in Au+Au collisions at RHIC for $s_{NN} = 7.7$ --39 GeV and different collision centralities. The produced medium is modeled as an expanding spherical fireball, with the radial expansion velocity determined from the rate of increase of the fireball radius. The particle spectra are calculated using the Cooper--Frye freeze-out prescription with a local equilibrium distribution function and a blast-wave-like flow profile. The model parameters are fixed from the midrapidity $p_{T}$ spectra of pions at kinetic freeze-out for different centralities. The same parameters are then used for the other hadron species, with the kinetic freeze-out chemical potential as the only additional free parameter. The model provides a good description of the STAR collaboration data for the $p_{T}$ spectra of light hadrons and predicts Gaussian-like rapidity distributions over the considered energy range across different centralities.
nucl-th0 citations
06
Relativistic Hydrodynamics and Vorticity Dynamics in High-Energy Heavy-Ion Collisions: A Collective Flow Perspective
Malak Ait Tamlihat🇲🇦 · Ghizlane Ez-Zobayr🇲🇦 · Laurent Schoeffel🇫🇷 · Yahya Tayalati🇲🇦
This article provides a comprehensive overview of the application of relativistic fluid mechanics to describe the collective evolution of the Quark-Gluon Plasma (QGP) formed in ultra-relativistic heavy-ion collisions. We map out the chronological transformation of spatial eccentricities in the initial interaction volume into measurable anisotropic azimuthal momentum distributions, parameterized by the harmonic flow coefficients $v_{n}$ . Utilizing multi-particle correlation techniques developed within the ATLAS experimental framework, we dissect the event-by-event fluctuations of the participant planes and evaluate non-linear hydrodynamic responses across higher harmonics. Furthermore, we embed local rotation fields into this continuous description by solving the covariant transport equations for subatomic vorticity. We demonstrate that while the Helmholtz-Kelvin theorem guarantees the topological conservation of vortex lines within the ideal medium, the collective multi-dimensional expansion forces a systematic 1/t power-law geometric dilution of the local rotational magnitude. Finally, we contrast different pre-equilibrium generation mechanisms and evaluate their final signatures on differential spin alignment observables.
nucl-thhep-ph0 citations
07
Theory of Spinful Relativistic Superfluids
Dam Thanh Son
We construct an effective field theory description of relativistic superfluids with nonzero angular momentum density. At first order in the derivative expansion, the effective action contains a term with a quantized coefficient, which encodes the Berry phase for the angular momentum of the superfluid condensate. From this single term we derive a number of physical effects, including the relativistic Mermin-Ho relation, an anomalous Ettingshausen effect (exchangeable for an anomalous Hall effect), and an anomalous Hall viscosity.
nucl-thcond-mat.supr-conhep-th0 citations
08
Equation of state of QCD(-like) theory using Lattice Monte Carlo simulations
Etsuko Itou🇯🇵
The equation of state (EoS) of strongly interacting matter at low temperature and high baryon density is a central ingredient in the physics of compact stars, but it is still difficult to determine directly from first-principles QCD calculations because of the sign problem. Two-colour QCD (QC $_{2}$ D) provides a useful and controllable laboratory: for an even number of fundamental flavours the fermion determinant is real and positive, while the theory shares the nonperturbative properties with three-colour QCD at least zero chemical-potential regime. In this short review we summarize recent lattice progress on dense QC $_{2}$ D, with emphasis on the phase structure, the emergence of superfluidity, the Bose--Einstein-condensation (BEC) to Bardeen--Cooper--Schrieffer(BCS) crossover, and thermodynamic quantities. A particularly interesting outcome is that the sound velocity in the cold dense superfluid regime can exceed the conformal value $c_{s}^{2} / c^{2} = 1/3$ . This behaviour, now seen in the simulations for several QCD-like theories, gives a stiff strongly interacting matter. It is expected to offer insight into at least some aspects of the physics realized inside neutron stars.
nucl-thhep-lathep-ph0 citations
09
$S$ matrices of elastic $n$ - $^{16}$ O scattering at low energies in cluster effective field theory
Shung-Ichi Ando
Elastic $n$ - $^{16}$ O scattering at low energies is studied in the framework of cluster effective field theory. An evaluated data set of the total cross section of elastic $n$ - $^{16}$ O scattering at neutron energy, $0 \leq E_{n} \leq 4$ ~MeV, is adopted from Evaluated Nuclear Data File (ENDF/B-VIII.0). We derive an expression for the $S$ matrices of the elastic scattering for seven spin-partial wave channels, $l j = s_{1/2}$ , $p_{1/2}$ , $p_{3/2}$ , $d_{3/2}$ , $d_{5/2}$ , $f_{5/2}$ , $f_{7/2}$ , including one excited state and nineteen resonant states of $^{17}$ O. Thirty-four parameters of the theory are fitted to the ENDF data, and we find that a plotted line, by using the fitted parameters, reproduces the ENDF data well. We discuss the uncertainties that may appear in the present approach from the fitted parameters of the resonant states with widths, larger than $Γ = 90$ ~keV. We also discuss the implications of the fitted values of energies and widths of the resonant states in the estimate of the astrophysical $S$ factor of $^{13}$ C( $α$ , $n$ ) $^{16}$ O reaction at stellar energies.
nucl-thnucl-ex0 citations
10
A Phenomenological Extension for Microscopic Optical Potentials
Matteo Vorabbi · Michael Gennari · Paolo Finelli · Carlotta Giusti · Petr Navrátil
Microscopic optical potentials constructed from realistic nucleon-nucleon interactions via multiple-scattering theory provide a first-principles description of nucleon-nucleus scattering. Nevertheless, such approaches often neglect medium corrections beyond Pauli blocking and fail to fully capture higher-order scattering contributions, leading to systematic under-prediction of absorption and deficiencies in angular distributions at low and intermediate energies. In this work we introduce a phenomenological correction scheme with an energy-dependent term designed to mimic correlation effects, dispersive contributions, and multi-step scattering processes. The correction is implemented in a minimal form to preserve the predictive character of the underlying microscopic model, while enabling improved flexibility in describing experimental observables. Applications to proton and neutron elastic scattering on light-mass nuclei demonstrate that the modified potentials yield enhanced agreement with measured differential cross sections, without sacrificing the microscopic foundation. This approach provides a practical pathway for incorporating missing medium and higher-order effects into optical model analyses relevant for nuclear structure and reaction studies.
nucl-th0 citations
11
High-precision ab initio calculations of nuclear binding energies: Tin isotopes from dripline to dripline
Urban Vernik🇩🇪 · Pepijn Demol🇧🇪 · Thomas Duguet🇧🇪 · Alexander Tichai🇩🇪
The location of the neutron drip line in tin isotopes has important consequences for our fundamental understanding of nuclear structure and nuclear forces as well as for astrophysical nucleosynthesis. Performing high-precision ab initio calculations of even-even tin isotopes from $N = 50$ to $N = 126$ based on chiral two- and three-nucleon interactions, the predicted drip-line location is found to be highly sensitive to the employed nuclear interactions and to exhibit tension with recent energy-density-functional predictions. On the neutron-deficient side, results are consistent with extrapolated two-neutron separation energies constrained by recent Penning-trap mass measurements.
nucl-thcond-mat.str-elnucl-ex3 citations

Affiliations

first authorsco-authorsvia INSPIRE