Nuclear Theory·nucl-th

Friday·April 10, 2026

16 papers—6 primary·10 cross-listed

01
[Submitted on 8 Apr 2026]
Statistical hadronization: successes and some open issues
A. Andronic · P. Braun-Munzinger · K. Redlich · J. Stachel
Hadron production in relativistic nuclear collisions is well described in the framework of the statistical hadronization model, over a broad range of collision energies. We outline this for hadrons composed of light (u, d, s) and heavy (charm and beauty) quarks, discuss recent findings relevant for understanding the phase structure of QCD and formulate some open issues.
Comments:
16 pages, 4 figures; prepared for the proceedings of the 66. Cracow School of Theoretical Physics "Physics of Strong Interactions under Extreme Conditions", 14-19.06.2026
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2604.07564 [pdf]
Acta Phys.Polon.B(2026)·0 citations
02
[Submitted on 8 Apr 2026]
Systematics of characteristics of pygmy dipole resonances in medium-heavy and heavy atomic nuclei with neutron excess
V. A. Plujko · O. M. Gorbachenko · N. O. Romanovskyi
The systematics of energies and the contribution of pygmy dipole resonance (PDR) to the energy-weighted sum rule of dipole gamma transitions in medium-heavy and heavy nuclei with an excess of neutrons are considered. The modified macroscopic model of Isacker-Nagarajan-Warner was used for calculating PDR energies with the number of surface neutrons proportional to the thickness of the neutron skin according to the Pethick- Ravenhall expression (PR INW approach). Such modification of the macroscopic approach by Isacker-Nagarajan-Warner enables to take into account microscopic evidence of direct relationship between skin thickness and low-energy dipole response. The results are compared with the microscopic calculations for the chains of Ni, Sn and Pb isotopes. It was demonstrated that the dependence of the magnitudes of the energies within the PR INW approach on neutron excess is in rather good agreement with experimental data and microscopic calculations if the absolute value of the strength of the neutron-proton interaction is nearly three times as large as that obtained by Isacker-Nagarajan-Warner by the volume integral of the nucleon-nucleon interaction. While the macroscopic INW PR model can describe the main features of the PDR, above mentioned discrepancy of the strength values doesn't not provide reason enough for the conclusion that PDR is pure collective state. The analytical expressions for the PDR fraction of the energy-weighted sum rule for electric dipole transitions (E1 EWSR) are used. They are based on the "molecular" energy-weighted E1 sum rule considering the number of surface neutrons as a function of the neutron thickness (PR MSR approach). Systematics for the PDR fraction of E1 EWSR are proposed with parameters obtained by fitting the experimental data and microscopic calculations.
Comments:
11 pages, 7 figures, accepted for publication in Physical Review C, DOI: https://doi.org/10.1103/2wq4-g4k3
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2604.07570 [pdf]
PRC(2026)·1 citation
03
[Submitted on 9 Apr 2026]
Investigation of the $K ˉ$ -- $^{6}$ Li Interaction and the Search for the $Λ (1405)$ Resonance
Ahmad Naderi Beni🇮🇷 · Sajjad Marri🇮🇷
We investigate the interaction of an antikaon ( $K^{-}$ ) with the $^{6}$ Li nucleus, described as an $α + d$ cluster system. The study aims to explore the formation of the $Λ (1405)$ resonance through the $K^{-} d$ subsystem in the presence of a spectator $α$ particle. In the absence of dedicated experimental data for this reaction, particular attention is given to providing quantitative predictions for the manifestation of the $Λ (1405)$ structure in low-energy $K ˉ N$ dynamics within a light nuclear environment. Employing different models of the $K ˉ N - π Σ$ interaction, we calculate the $π Σ n$ invariant-mass spectra and the $α$ -particle missing-mass spectra, thereby identifying robust features of the $Λ (1405)$ signal and offering guidance for future experimental investigations.
Comments:
4 figures, Accepted for publication in PRC
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2604.07871 [pdf]
PRC(2026)·0 citations
04
[Submitted on 9 Apr 2026]
The neutron skin effect in Pb+Pb collisions at 2.76A TeV at the LHC
Amit Paul🇮🇳 · Rupa Chatterjee🇮🇳
Collisions of lead nuclei at relativistic energies provide valuable insight into the properties of the quark gluon plasma formed in such collisions where the initial geometry and density profile play a crucial role in governing the subsequent evolution of the produced hot and dense fireball. The neutron skin thickness resulting from the difference between the neutron and proton density distributions in neutron rich lead nuclei plays an important role in nuclear structure studies. In this work we investigate the impact of neutron skin on the space time evolution of the fireball formed in Pb+Pb collisions at 2.76A TeV at the LHC and analyze how the presence of neutron skin affect bulk observables sensitive to the initial nuclear structure. The time evolution of initial profile along with the average $p_{T}$ , particle spectra and anisotropic flow parameters are estimated to investigate the effect of neutron skin on these observables. The initial spatial anisotropy of the fireball is found to be affected by the neutron skin thickness significantly especially for the peripheral collisions. This leads to a substantial enhancement of the elliptic flow of hadrons with an even stronger effect observed for photons. In addition, the effect is found to be more pronounced for lower beam energy collisions of lead nuclei.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2604.08136 [pdf]
0 citations
05
[Submitted on 9 Apr 2026]
High-precision ab initio nuclear theory: Learning to overcome model-space limitations
Marco Knöll
High-precision predictions of nuclear properties are a central objective of ab initio nuclear structure theory. However, state-of-the-art many-body methods rely on truncated model spaces to render the nuclear many-body problem tractable, which remains a major source of theoretical error in computations of nuclear observables. In recent years, machine learning, and artificial neural network approaches in particular, have emerged as a powerful data-driven framework for learning convergence patterns directly from ab initio calculations and enabling precision extrapolations beyond the reach of conventional schemes. This review focuses on model-space extrapolation methods developed for the no-core shell model and related many-body methods. We discuss machine learning extrapolation frameworks in comparison to conventional methods and assess their performance for energy spectra, radii, and electromagnetic observables, with particular emphasis on achievable precision and uncertainty estimates through statistical and correlation-based strategies. These developments establish machine learning as an increasingly important component of the precision toolbox in ab initio nuclear theory, enhancing the reliability and predictive power of ab initio nuclear structure calculations.
Comments:
16 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2604.08253 [pdf]
J.Phys.G(2026)·1 citation
06
[Submitted on 9 Apr 2026]
Relativistic mean-field models of neutron-rich matter
J. Piekarewicz
The aim of this chapter, focused on relativistic mean-field models and part of the Encyclopedia of Nuclear Physics, is to provide an introductory, self-contained discussion accessible to a broad audience, including advanced undergraduate students. The chapter surveys the fundamental ideas, assumptions, and theoretical framework underlying relativistic mean-field models, and illustrates their wide range of applications across nuclear science. Particular emphasis is placed on the central role that these models play in the construction of equations of state for strongly interacting matter, as well as on the intimate connections between nuclear experiments, astrophysical observations, and theoretical modeling. In this context, relativistic mean-field theory is shown to provide a unified description of bulk nuclear properties and dense neutron-rich matter, enabling the interpretation of the remarkable structural and observational properties of neutron stars in the emerging era of multi-messenger astronomy.
Comments:
13 pages, 5 figures, contribution to the Encyclopedia of Nuclear Physics
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
2604.08286 [pdf]
0 citations
07
[Submitted on 8 Apr 2026] (cross-list from hep-ph)
Excitation function for global \Lambda polarization in relativistic heavy ion collisions with the Core Corona model
Alejandro Ayala🇲🇽 · José Jorge Medina Serna🇲🇽 · Isabel Domínguez🇲🇽 · María Elena Tejeda-Yeomans🇲🇽
We compute the excitation function of the global $Λ$ polarization in semicentral heavy-ion collisions within a Core--Corona framework, where the interaction region is described as a dense core and a dilute corona separated by a critical value of the participant density. An important ingredient in the model are the intrinsic polarization functions in each of the two regions. These are computed from a field-theoretical approach where the vortical motion of the medium is included in an effective fermion propagator, which we derive explicitly. The interactions in the core and the corona are transmitted by suitable mediators at finite temperature and baryon chemical potential; gluons for the former and $σ$ -mesons for the latter. The temperatures and baryon chemical potentials are related to the collision energies along the chemical freeze-out curve. By allowing the cross section for $Λ$ production in the nuclear environment to take on values below the nucleon-nucleon threshold cross section, the calculation describes the lowest energy polarization data point. For the centralities corresponding to the experimental data, we find that the contribution from the corona is the dominant one and that a lifetime, and correspondingly a volume of this region, which becomes larger for the smaller energies due to stopping, is an essential ingredient in the calculation. Overall, the model provides a good description of the excitation function across the full experimental range and predicts a robust maximum near $s_{N N} \sim$ 3 GeV that remains stable under reasonable variations of the freeze-out curve and the proton-proton $Λ$ production threshold to account for subthreshold production in a nuclear environment.
Comments:
14 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2604.07501 [pdf]
0 citations
08
[Submitted on 8 Apr 2026] (cross-list from hep-ph)
Forward trijet production in proton-nucleus collisions: gluon initiated channel
Paul Caucal🇫🇷 · Marcos Guerrero Morales🇺🇸 · Farid Salazar🇺🇸
In this paper, we present results for the forward three-parton production differential cross section in the gluon-initiated channel in proton-nucleus collisions. This result is the leading-order contribution to forward trijet production and provides the real-emission building block required for the NLO dijet/dihadron cross section. The calculations are carried out within the Color Glass Condensate (CGC) effective theory, and in the dilute-dense approximation, using effective vertices for the quark and gluon propagators interacting with the small- $x$ background gluon field. We employ the covariant perturbation theory approach and disentangle the amplitudes into regular and instantaneous contributions. Our results are expressed as convolutions of multiparton color correlators of light-like Wilson lines and perturbative impact factors, organized in compact expressions in terms of the ``bare" topologies of the contributing diagrams. The gluon-initiated channel receives contributions from a $q q ˉ g$ and a $g g g$ final state. Interestingly, when considering the $g g g$ final state, we observe, for the first time, that the four-gluon vertex topology follows a structure similar to the instantaneous contributions. This observation suggests a simplification in the organization of multigluon CGC amplitudes and may prove useful for future one-loop calculations. Furthermore, when integrating (one of) the real gluon(s) in the final state, we identify that the rapidity divergence is absorbed into the real part of the JIMWLK evolution of the leading-order Wilson-line correlator. In addition, we isolate the divergences arising when the unobserved parton becomes collinear to one of the observed hadrons in the final state. These divergences are absorbed by renormalizing the initial-state parton distribution functions and final-state fragmentation functions, which are shown to obey DGLAP evolution.
Comments:
v2: version accepted for publication in JHEP, 75 pages, 12 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2604.07509 [pdf]
JHEP(2026)·3 citations
09
[Submitted on 8 Apr 2026] (cross-list from astro-ph.HE)
Which Neutron Stars Reach the Stiffening Regime? Multimessenger Constraints on Core Sound Speed and Stellar-Mass Thresholds
Nicolás Viaux · Sebastián Mendizabal
We present a concise multimessenger inference of the neutron-star core sound-speed profile using GW170817 and three \textit{NICER} mass--radius posteriors (PSR J0030 $+$ 0451, PSR J0740 $+$ 6620, and PSR J0437 $-$ 4715). The main result is not only a preference for intermediate-density stiffening within smooth equation-of-state families, but a translation of that inference into the stellar masses that access the relevant density regime. In the baseline smooth peaked family, the posterior probability that $c_{s}^{2} > 1/3$ at $3.5 n_{sat}$ is $85.4 %$ , while equal-prior averaging over peaked, monotonic, piecewise, and transition-capable families gives a more conservative $79.0 %$ . Posterior-resampled exact Tolman--Oppenheimer--Volkoff solutions show that the onset density of the inferred stiffening is typically reached near $1.6 M_{⊙}$ , whereas the peak region is accessed only near $2.1 M_{⊙}$ . A J0740-like $2.07 M_{⊙}$ pulsar reaches the onset in $91 %$ of posterior draws but the peak in only $46 %$ , showing that current data mainly constrain whether massive stars have entered the stiffening regime rather than traversed its full peak.
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2604.07542 [pdf]
0 citations
10
[Submitted on 8 Apr 2026] (cross-list from hep-ph)
Transverse energy-momentum tensor distributions in polarized nucleons
Ho-Yeon Won🇫🇷 · Cédric Lorcé🇫🇷
We complete our study of the relativistic spatial distributions of the energy-momentum tensor inside polarized nucleons within the quantum phase-space formalism. In the present work, we focus on the components of the energy-momentum tensor involving at least one transverse index. We also explore the multipole structure of the transverse distributions in a moving nucleon. In the infinite-momentum frame, we show that the formalism reproduces the standard light-front distributions, including those with a ``bad'' component, and explains the origin of their structure.
Comments:
11 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2604.07616 [pdf]
PRD(2026)·1 citation
11
[Submitted on 8 Apr 2026] (cross-list from hep-th)
Gaussian pseudogauge invariant hydrodynamics with spin
David Montenegro · Mariana Julia Pereira Dos Dores Savioli · Giorgio Torrieri
Extending the Gaussian covariant hydrodynamics approach [1] using torsion as an auxiliary field we formulate a fluctuating hydrodynamics with spin which is covariant with respect to pseudo-gauge transformations as well as generally covariant with respect to foliations. This is done via the second order gravitational Ward identities, derived here in the torsionful case. This ensures that, while angular momentum observables depend covariantly on the pseudo-gauge, the dynamics is pseudo-gauge independent, thus clarifying the role of the pseudo-gauge in hydrodynamics with spin
Comments:
Comments, criticisms, questions and suggestions welcome
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2604.07657 [pdf]
2 citations
12
[Submitted on 9 Apr 2026] (cross-list from nucl-ex)
Wave-Function Femtometry: Hypertriton - The Ultimate Halo Nucleus
ALICE Collaboration
The interaction between nucleons and hyperons - baryons containing a strange quark - is key to understanding the properties of dense nuclear matter, such as that expected in the interior of neutron stars. Direct scattering experiments are hindered by the short lifetime of hyperons, prompting the study of hypernuclei - bound states of nucleons and hyperons - as an alternative approach. The lightest known hypernucleus, the hypertriton ( $_{Λ}^{3}$ H), is a weakly bound state composed of a proton, a neutron and a $Λ$ hyperon, and is believed to exhibit a halo-like structure with the $Λ$ being loosely bound to a deuteron core. Based on the first measurement of hypertriton production in proton-proton collisions at the CERN Large Hadron Collider (LHC), its halo structure is confirmed. A successful description of the hypertriton production yield within the nuclear coalescence framework enables an estimation of the $Λ$ separation from the deuteron core as $9.5 4_{- 1.11}^{+ 2.67}$ fm.
Comments:
29 pages, 5 captioned figures, 2 tables, authors from page 24, submitted to Nature, figures at http://alice-publications.web.cern.ch/node/13213
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2604.07949 [pdf]
1 citation
13
[Submitted on 9 Apr 2026] (cross-list from hep-ph)
Memory effect on the heavy quark dynamics in hot QCD matter
Jai Prakash🇨🇳 · Ling Hai Li🇨🇳 · Ying Shan Zhao🇨🇳 · Yifeng Sun🇨🇳
We study the heavy quark dynamics in the presence of memory within the framework of a generalized Langevin equation. Time correlated thermal noise with power-law decay is generated by a fractional differential equation, formulated using the Caputo fractional derivative with order parameter $ν$ . The effect of memory is calculated through the momentum correlation, the time evolution of the average squared momentum, the average squared displacement, and the average kinetic energy. The effect of memory is further studied for the higher normalised central moments of the heavy quark transverse-momentum distribution. The results indicate that time correlated thermal noise substantially influences heavy quark dynamics in the quark gluon plasma.
Comments:
12 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2604.07982 [pdf]
PRD(2026)·1 citation
14
[Submitted on 9 Apr 2026] (cross-list from physics.chem-ph)
From Full Dynamic to Pure Static: A Family of $G W$ -Based Approximations
Pierre-François Loos · Johannes Tölle
We introduce a systematic hierarchy of one-body Green's function methods derived from the $G W$ approximation, constructed by progressively reducing the dynamical content of the self-energy. Starting from the fully dynamical Dyson formulation, we generate a family of approximations that interpolates between the standard $G W$ approximation to purely static effective single-particle Hamiltonians. This framework enables a controlled investigation of the role of dynamical effects and particle-hole coupling in the description of ionization potentials. Within this unified formalism, the hole and particle branches can be selectively decoupled through downfolding strategies into reduced one-particle spaces. By benchmarking the different members of this hierarchy on molecular ionization energies, we assess their accuracy, numerical robustness, and algorithmic complexity. We demonstrate that consistently derived partially static schemes can yield reliable quasiparticle energies while significantly simplifying the underlying eigenvalue problem. We further introduce a novel static Hermitian self-energy obtained as the static limit of this hierarchy. Despite its conceptually distinct origin, it produces results remarkably close to those of qs $G W$ , thereby providing an alternative static route toward partial self-consistency.
Comments:
10 pages (Supporting Information available)
Subjects:
physics.chem-ph (physics.chem-ph); cond-mat.mtrl-sci (cond-mat.mtrl-sci); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th)
arXiv:
2604.08350 [pdf]
J.Chem.Phys.(2026)·0 citations
15
[Submitted on 9 Apr 2026] (cross-list from physics.atom-ph)
Nuclear forward scattering of Bessel beams in $^{229}$ Th:CaF $_{2}$
Alexander Franz · Tobias Kirschbaum · Adriana Pálffy
The coherent pulse propagation of a Bessel beam resonant to the 8.4 eV nuclear clock transition in $^{229}$ Th-doped crystals is investigated theoretically. Due to the magnetic dipole character of the clock transition, Bessel beams which present non-uniform transverse profiles and carry orbital angular momentum might enhance excitation channels or offer new control degrees of freedom compared to standard plane waves. We model the nuclear forward scattering of a resonant Bessel beam pulse propagating through the crystal, extending an formalism based on the iterative wave equation for plane waves. Thereby we take into account the nuclear quadrupole splitting in the crystal, considering the possibility of multiple quantization axes and present results for scenarios involving a single nuclear transition and multiple simultaneously driven transitions, analyzing temporal and spatial intensity patterns. Our findings show that the propagation of Bessel beams can be used to determine the relative distribution of different directions of quantization axes inside the crystal.
Comments:
17 pages, 13 figures
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
arXiv:
2604.08433 [pdf]
0 citations
16
[Submitted on 9 Apr 2026] (cross-list from hep-ph)
Kinetic and canonical momentum broadening in the Glasma
Dana Avramescu🇫🇮 · Carlos Lamas🇪🇸 · Tuomas Lappi🇫🇮 · Meijian Li🇪🇸 · Carlos A. Salgado🇪🇸
We lay the foundations for a quantum formalism describing the real-time evolution of particles in the Glasma phase of a heavy-ion collision, focusing on the implications of gauge invariance in the definition of the momentum of a particle in a classical background field. We first establish the correspondence between the classical Wong's equations and the Heisenberg equations of motion for a particle in a classical non-Abelian background field. Using this correspondence, we obtain equations of motion for both the kinetic momentum -- the gauge invariant, physically measurable quantity -- and the canonical momentum, which is conjugate to the coordinates in the Hamiltonian. In particular, the kinetic momentum broadening receives non-trivial contributions from the transverse field components, even in the eikonal limit. Finally, we demonstrate that imposing a transverse Coulomb gauge condition at the initial time significantly reduces the accumulation of numerical errors, thereby providing an optimized framework for the forthcoming quantum implementation.
Comments:
20 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2604.08520 [pdf]
2 citations

Affiliations

first authorsco-authorsvia INSPIRE