Nuclear Theory·nucl-th

Wednesday·June 3, 2026

16 papers—10 primary·6 cross-listed

01
[Submitted on 1 Jun 2026]
Interaction Cross Sections as a Structural Probe of the Hypertriton Halo
C.A. Bertulani🇺🇸
The hypertriton ( $_{Λ}^{3} H$ ) is the most weakly bound known hypernucleus and one of the most spatially extended quantum halo systems observed in nature. Despite decades of experimental and theoretical effort, its matter radius and $Λ$ separation energy remain incompletely constrained. We demonstrate theoretically that interaction cross-section measurements provide a direct and highly sensitive probe of both quantities. Realistic three-body hypertriton wavefunctions are combined with a coupled-channel Glauber theory incorporating proton, neutron, and hyperon densities together with $Λ N \leftrightarrow Σ N$ channel coupling. The resulting interaction cross section changes by about 400 mb across the currently allowed range of $Λ$ separation energies while retaining theoretical uncertainties below approximately 5\%. A Bayesian inversion demonstrates that future interaction cross-section measurements can determine both the hypertriton matter radius and the $Λ$ separation energy with potentially unprecedented precision. These results establish interaction cross sections as a new structural observable for hypernuclear halo physics.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.02923 [pdf]
0 citations
02
[Submitted on 2 Jun 2026]
Chemical Equilibration and Thermalization of Quark-Gluon Plasma in a Parton Cascade Model with 2-to-3 Quark Interactions
Cendikia Abdi🇯🇵 · Chiho Nonaka🇯🇵
We investigate the thermalization, chemical equilibration, and hydrodynamization behavior of the far-from-equilibrium, gluon-dominated quark gluon plasma (QGP) produced in Au+Au collisions at $s_{NN} = 200$ GeV using the hadronic transport model SMASH extended to simulate partonic interactions. The initial conditions are prepared using the mini-jet model with nuclear parton distribution functions. We first validate the model in a box simulation with the periodic boundary condition to establish indicators for thermalization, chemical equilibration, and hydrodynamization by analyzing energy spectrum and momentum anisotropy. We observe that the additional inelastic channels accelerate thermalization and chemical equilibration compared to the gluon-only scheme. Applying the same framework to the expanding medium, we find that the energy spectrum converges toward the Boltzmann distribution at $t \sim 0.2$ fm while momentum isotropization is achieved at $t \sim 2$ fm, but chemical equilibration is not clearly established even after 5 fm. The Knudsen number rises above unity after $\sim 4$ fm, indicating a breakdown of the hydrodynamic regime at later times consistent with other kinetic theory approaches.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.03058 [pdf]
1 citation
03
[Submitted on 2 Jun 2026]
How long can a non-spherical quantum object remain standing ? - a fundamental quantum question -
Takaharu Otsuka · Yusuke Tsunoda
An isolated quantum system generally exhibits rotational symmetry, i.e., conserved spin (angular momentum) in its eigenstates. Non-spherical quantum objects such as many of molecules and atomic nuclei are not exceptions. However, these objects are not rotationally invariant by definition. Such an object therefore restores, as a consequence of the action of Hamiltonian, the rotational symmetry by superposing states of the same object orienting in different directions, where each component represents one direction. We show the time evolution of an individual component of this superposition: this component remains almost unchanged for finite time, called standing time. This implies that if the object is found to be in this component, it basically remains so for the standing time. This feature is shown to be relevant in a variety of cases, such as atomic nuclei, polymers (proteins), and electron drops in atoms. The shapes of many nuclei are ellipsoids with variations. The "viewing" of the ellipsoidal shape is not straightforward, because this ellipsoid is not at rest. A "snapshot" of a nucleus is highly desired as a direct information. Recent experimental approaches with Relativistic Heavy-ion Collision (RHC) are promising for taking such a snapshot. The present work depicts that the standing time, some 10^{-23} sec for typical ellipsoidal nuclei, is much longer than the time scale of RHC, some 10^{-25} sec. This implies that an ellipsoidal nucleus remains practically unchanged for this critical period. As the standing time will be intimately related, through a relation like the energy-time uncertainty relation, to the energy scales involved, we can also explore this concept and its applications in a variety of physical cases such as fusion (tunneling process), fission, alpha-decay/emission, polymers and electron drop in atom.
Comments:
13 pages, 5 figures, revisions for the title, abstract and introduction. Two sections, polymer (protein) and electron drop, have been added. Minor revisions for the rest
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2606.03272 [pdf]
0 citations
04
[Submitted on 2 Jun 2026]
Non-monotonicity of $p_{T}$ correlations from meson-baryon mixing
Tom Reichert🇨🇭 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪
The STAR experiment has recently reported data on the $⟨ Δ p_{T, i} Δ p_{T, j} ⟩ / ⟨⟨ p_{T} ⟩⟩$ charged hadron correlation in Au+Au reactions from $s_{N N} = 3 - 200$ GeV. The beam energy dependence of this quantity is non-monotonic, showing a pronounced minimum at $s_{N N} \approx 7.7$ GeV, while being essentially flat at lower and higher energies. It has been proposed that such a non-monotonicity would be consistent with increased momentum correlations due to a critical point of QCD. In the present work it is shown, using a simplified model, that the observed structure can be consistently explained by the transition from a baryon dominated system to a meson dominated system and is therefore not a good observable for the critical point of QCD.
Comments:
8 pages, 4 figures,
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2606.03294 [pdf]
1 citation
05
[Submitted on 2 Jun 2026]
Relation between E2 transitions in even--even and odd-mass nuclei
P. Van Isacker
How is the B(E2;2_1^+ -> 0_1^+) value in an even-even nucleus related to corresponding B(E2;J_i -> J_f) values in a neighbouring odd-mass nucleus? If either neutrons or protons are confined to a single-j orbital and if the nucleon--nucleon interaction conserves seniority, a simple relation between the two properties is obtained, which may differ from what is found in the weak-coupling limit of the core-particle model. This single-j relation is substantially perturbed if several non-degenerate orbitals are considered. An application to recently measured B(E2) values in neutron-deficient tin isotopes is presented.
Comments:
12 pages, 2 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.03525 [pdf]
EPJ Web Conf.(2025)·0 citations
06
[Submitted on 2 Jun 2026]
Mechanical properties of the nucleon in the chiral confining model. I -- formal developments
Guy Chanfray🇫🇷 · Hubert Hansen🇫🇷 · Bikram Keshari Pradhan🇫🇷
We discuss the issue of the mechanical stability of the nucleon within a class of models in which massive constituent quarks are subject to a confining potential and are coupled to a surrounding pion cloud enveloping the quark core. The nucleon trial states (either localized factorized wave functions or momentum-projected states) are determined by imposing the von Laue stability condition. This article is primarily devoted to the formal aspects related to the detailed expressions for the total energy (mass), the average pressure, the energy density and the pressure distribution inside the nucleon. It will be accompanied by a complementary article addressing the evolution of nucleon properties with density, associated with the restoration of chiral symmetry.
Comments:
25 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.03588 [pdf]
1 citation
07
[Submitted on 2 Jun 2026]
Mechanical properties of the nucleon in the chiral confining model. II -- in-medium evolution of the nucleon properties
Guy Chanfray🇫🇷 · Hubert Hansen🇫🇷 · Bikram Keshari Pradhan🇫🇷
This article is devoted to the study of the evolution of the properties of nucleons bound in nuclear matter within the framework of the chiral confining model. The in-medium nucleon trial states (either localized factorized wave functions or momentum-projected states) are determined by imposing the von Laue stability condition, according to the formal results established in a preliminary companion paper (labeled as I). The main results concern the response of the composite nucleon to the scalar field, as well as the respective roles of confinement and chiral symmetry breaking in the evolution of the in-medium nucleon mass. This evolution governs the repulsive three-body forces required for the nuclear saturation mechanism. We also analyze the modification of the energy density distribution and the pressure distribution inside the in-medium nucleon. We also draw some perspectives concerning the mapping between bound nucleon properties and the equation of state of dense matter as realized in the deep interior of neutron stars.
Comments:
22 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.03633 [pdf]
1 citation
08
[Submitted on 2 Jun 2026]
Nuclear Reaction Data for Fission Products Off Stability
Gustavo Nobre · Emanuel Chimanski · Aman Sharma · Alexander Voinov · Kyle Wendt · David Brown · Shusen Liu
Neutron cross sections on fission products are relevant to a wide range of applications, including nuclear nonproliferation and forensics, spent-fuel assay, reactor burnup and design, as well as astrophysics. Evaluated nuclear data libraries generally fulfill application needs for isotopes on or near stability, however, for unstable fission products, theoretical descriptions of neutron-induced reactions often constitute the only available source of information. These models often make use of simplified assumptions, leading to unquantified impacts on predicted cross sections. In this work, we discuss possible approaches to addressing these issues, particularly by leveraging machine-learning methods, improved predictive reaction modeling, and experimental data to better constrain model parameters. Our goal is to eventually produce evaluated files for the most-produced nuclei off stability in the fission process of $^{235}$ U and submit them to the ENDF/B for consideration in the future ENDF/B-IX.0 release. Here we present the methodology and discuss preliminary results comparing usual simplified approaches with a more realistic one accounting for nuclear deformation.
Comments:
4 pages, 3 figures. Submitted to the proceedings of the 2025 Nuclear Data Conference (ND2025)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.03720 [pdf]
0 citations
09
[Submitted on 2 Jun 2026]
Revisiting neutron-skin thickness and dipole polarizability constraints on the symmetry energy in Antisymmetrized Molecular Dynamics
Dandan Niu · Luqi Li · Xinyu Wang · Ping Feng · Qiang Zhao · Kai Zhao · Akira Ono · Yingxun Zhang
The neutron-skin thickness and electric dipole polarizability are among the most sensitive probes of the symmetry energy at subsaturation densities. Motivated by the tension raised by recent analyses of PREX-II and CREX data within density-functional-based approaches, we perform a unified study of static and dynamical isovector observables within the antisymmetrized molecular dynamics (AMD) framework. Using thirty interaction parameter sets that span different values of the symmetry-energy coefficient $S_{0}$ , slope parameter $L$ , and neutron-proton effective-mass splitting $Δ m_{n p}^{*}$ , we systematically analyze the neutron-skin thicknesses of nuclei from $^{40}$ Ca to $^{238}$ U together with the electric dipole polarizability $α_{D}$ of $^{208}$ Pb. A combined $χ^{2}$ analysis of neutron-skin thicknesses and the electric dipole polarizability yields preferred values of $L$ that increase with $S_{0}$ , reflecting the joint constraint from the static and dynamical observables. Furthermore, we identify the density region mainly probed by these observables as 0.019 $\leq ρ / ρ_{0} \leq$ 0.60, where the relative narrowing strength function varies by less than 10% compared to its maximum narrowing strength. The maximum reduction of the uncertainty of $S (ρ)$ occurs at 0.28 $ρ_{0}$ , where the symmetry energy within 1 $σ_{p os t}$ uncertainty is constrained to be $S (0.28 ρ_{0}) = 13.84 \pm 1.31$ MeV. These results demonstrate that a unified AMD analysis of neutron-skin systematics and dipole polarizability provides a complementary constraint on the symmetry energy below saturation density.
Comments:
9 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2606.03760 [pdf]
0 citations
10
[Submitted on 2 Jun 2026]
Yoctosecond imaging of the ground state of $^{129}$ Xe at the Large Hadron Collider
Giuliano Giacalone🇨🇭 · Govert Nijs🇨🇭 · Wilke van der Schee🇨🇭
Imaging a quantum many-body system requires probes that resolve the coordinates of its constituents in sufficiently large event samples, allowing measurements of correlation functions [1-4]. High-energy nuclear collisions provide this opportunity on the nuclear scale [5], enabling features of colliding ions, such as their deformation, to be probed through particle correlation observables [6, 7]. However, a quantitative extraction of the correlation properties of nuclei from these measurements is still lacking. Here we show that this is possible for the nucleus $^{129}$ Xe using Bayesian inference methods. We combine a deformed-rotor description of the colliding nuclei, which encodes the many-body dynamics of constituent neutrons and protons, with hydrodynamic simulations of the ensuing collision evolution. From a combined global analysis of Large Hadron Collider data on Xe-Xe and Pb-Pb collisions, we then infer that the shape of $^{129}$ Xe is nearly maximally triaxial, which aligns with mean-field results for xenon isotopes away from shell closure [8, 9]. From this we evaluate two- and three-particle correlations in the nuclear ground state to provide new constraints for \textit{ab initio} methods in nuclear theory. We establish thus collider experiments as a means of quantifying correlations of protons and neutrons arising from residual forces of quantum chromodynamics.
Comments:
6 pages, 4 figures plus supplemental. Comments welcome
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2606.03993 [pdf]
2 citations

Affiliations

first authorsco-authorsvia INSPIRE