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
11
[Submitted on 21 May 2026] (cross-list from astro-ph.HE)
Hybrid stars among mass gap objects are excluded by twin stars at $1.4 M_{⊙}$
Alexander Ayriyan🇵🇱 · David Blaschke🇵🇱 · Marcin Dubaj🇵🇱 · Oleksandr Vitiuk🇵🇱 · Adrian Wojcik
We investigate the question whether compact objects in the so called mass gap ( $2.5 < M / M_{⊙} < 5.0$ ) can be neutron stars or hybrid stars. Using a generic hybrid star equation of state with a first-order deconfinement transition, we map the allowed parameter space in a Seidov-type diagram and confront it with modern mass--radius constraints. We find that mass-gap hybrid stars require an extremely early onset of deconfinement and very stiff quark matter. The Bayesian analysis, however, favors equations of state with deconfinement at typical neutron-star masses around $1.4 M_{⊙}$ with mass-twin stars that, if confirmed, would rule out hybrid stars as candidates for observed mass-gap compact objects.
Comments:
6 pages, 2 figures, figure1 updated, link to open data repository added, version submitted to ApJ Letters
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2606.02593 [pdf]
0 citations
12
[Submitted on 1 Jun 2026] (cross-list from hep-ph)
Stochastic Dynamics of Heavy Quarks in Strongly Coupled Plasma
Krishna Rajagopal🇺🇸 · Bruno Scheihing-Hitschfeld🇺🇸 · Urs Achim Wiedemann🇨🇭
We study the stochastic dynamics of heavy quarks propagating through the strongly coupled plasma of $N = 4$ supersymmetric Yang-Mills (SYM) theory at nonzero temperature in terms of the corresponding Kolmogorov equation, which correctly describes their kinetic equilibration and the non-Gaussian fluctuations in their momenta without having to restrict their velocity to the non-relativistic regime. Leveraging the heavy quark limit, we show that the evolution of the momentum space distribution function can be reformulated as a Hamilton-Jacobi problem, and therefore can be solved in terms of first-order ordinary differential equations. We solve these evolution equations in an infinite thermal plasma with a constant temperature for initial conditions specified by spherically symmetric heavy quark momentum distributions with a phenomenologically motivated shape that is steeply falling at large momentum. To highlight the distinctive features of the kinetic equilibration process, we compare their solutions with Fokker-Planck dynamics with the same drag coefficient and fluctuations chosen by hand to guarantee equilibration. We find qualitatively similar dynamics at small momentum, and very different dynamics at large momentum, where, much like in jet quenching phenomena, the steepness of the momentum distribution gives a larger relevance to unlikely events in which a heavy quark loses little momentum in a given time step. Such events are much less unlikely in the Kolmogorov evolution than in Fokker-Planck evolution with the same mean energy loss, meaning that equilibration at large momentum is significantly delayed. Our results provide a systematic description of heavy quarks propagating through strongly coupled plasma from the ultra-relativistic to the non-relativistic regime and point the way towards implementation in phenomenological studies.
Comments:
71 pages, 16 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2606.02693 [pdf]
4 citations
13
[Submitted on 1 Jun 2026] (cross-list from hep-ph)
Projected Energy Correlators: Two-Loop Jet Functions and NNLL Resummation
Kyle Lee🇺🇸 · Yibei Li🇩🇪 · Zhen Xu🇩🇪 · Xiaoyuan Zhang🇺🇸
We present the next-to-next-to-leading logarithmic (NNLL) collinear resummation of projected $N$ -point energy correlators (ENCs) up to $N = 6$ , matched to fixed-order predictions at NLO, in both electron-positron annihilation and Higgs decay to gluons. The key new ingredient is the two-loop jet function for $N = 4, 5, 6$ , which we compute semi-analytically using Integration-by-Parts and differential equations. We further include the leading non-perturbative corrections for ENCs, described by two universal soft matrix elements $Ω_{1 q}, Ω_{1 g}$ of order $Λ_{QCD}$ , whose evolution is governed by anomalous dimensions for $(N - 1)$ -point correlators. The matched distributions are compared with parton-shower simulations from Pythia8 and Herwig7, and we study the sensitivity of both the absolute spectra and their ratios to the two-point energy correlator under variations of $α_{s}$ and $Ω_{1 q, 1 g}$ . Our results show that higher-point projected energy correlators are now under quantitative control at NNLL accuracy, opening the door to future $α_{s}$ extractions with complementary systematics.
Comments:
36 pages + appendices, 15 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2606.02714 [pdf]
5 citations
14
[Submitted on 1 Jun 2026] (cross-list from hep-ph)
Magnetized bottom-up thermalization in heavy-ion collisions
Ritesh Ghosh🇹🇼 · Igor A. Shovkovy🇺🇸
We investigate how a strong magnetic field generated in noncentral heavy-ion collisions may modify the bottom-up equilibration scenario. In the conventional weak-coupling picture, the earliest stages of the evolution are dominated by overoccupied gluons, while quark production is parametrically delayed. In a background magnetic field, however, additional inelastic channels become kinematically allowed or enhanced, most notably gluon decay into quark-antiquark pairs, $g \to q + q ˉ$ . Using parametric estimates, we show that for sufficiently strong fields, with $∣ e B ∣$ approaching the saturation scale squared, $Q_{s}^{2}$ , magnetic-field-induced quark production can become important during the earliest stages of bottom-up evolution. This mechanism can populate the hard quark sector, modify the chemical composition of the pre-equilibrium matter, and provide an additional pathway toward chemical equilibration. We also discuss possible back-reaction effects, including quark-antiquark annihilation, depletion of the hard-gluon sector, and the potential feedback of early quark production on the electromagnetic conductivity of the medium. This exploratory study of a magnetically assisted bottom-up scenario provides a natural extension of the standard framework, with qualitative predictions that depend sensitively on the lifetime and spacetime profile of the magnetic field.
Comments:
10 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2606.02723 [pdf]
0 citations
15
[Submitted on 2 Jun 2026] (cross-list from hep-ph)
Chiral Quark Soliton Model And Nucleon Parton Distribution Functions
Masashi Wakamatsu🇯🇵
The chiral quark soliton model (CQSM) is an effective quark model of baryons maximally taking account of the most important feature of low-energy QCD, i.e., the spontaneous chiral symmetry breaking of the QCD vacuum and the associated appearance of Nambu--Goldstone pions. It shares many common features with the famous Skyrme model in that the baryons are viewed as rotating hedgehog objects in both models. Despite many similarities, it turned out that the CQSM can give more realistic predictions on most baryon observables. Above all, a decisive advantage of the CQSM over the Skyrme-like models is that it can handle non-local quark--quark correlations in baryons, which is absolutely impossible within the framework of effective meson theories. This feature is decisively important for making theoretical predictions on the quark distribution functions inside the nucleon, which are defined as nucleon matrix elements of bilinear quark operators with light-cone separation. In the present paper, we try to elucidate why and how the CQSM can give successful predictions for a variety of types of nucleon quark distribution functions, especially for the flavor asymmetry of the unpolarized and longitudinally polarized sea-quark (anti-quark) distribution functions in the nucleon.
Comments:
40 pages, 17 figures, Invited contribution to the Special Issue of Symmetry, titled "Chiral Quark Models and Their Applications"
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2606.03042 [pdf]
Symmetry(2026)·0 citations
16
[Submitted on 2 Jun 2026] (cross-list from hep-ph)
Phase structure of strong interaction matter from Functional QCD
Christian S. Fischer🇩🇪 · Jan M. Pawlowski🇩🇪
In this contribution to the Encyclopedia of Nuclear Physics, we aim to provide a pedagogical introduction to the functional approach to QCD at finite temperature and chemical potential. We briefly outline the general framework and address its complementarity to other first-principle approaches to non-perturbative QCD. We discuss selected results obtained with Dyson-Schwinger equations (DSE) and the functional renormalisation group (fRG) in the context of a general physics perspective on the QCD phase diagram. This article is specifically aimed at students and non-practitioners of functional methods alike and may serve as a short guide to further literature.
Comments:
21 pages, 6 Figures, Contribution to the Encyclopedia of Nuclear Physics
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2606.03703 [pdf]
5 citations

Affiliations

first authorsco-authorsvia INSPIRE