Nuclear Theory·nucl-th

Tuesday·June 23, 2026

31 papers—16 primary·15 cross-listed

01
[Submitted on 19 Jun 2026]
Ab Initio Nuclear Theory for Heavy Nuclei and Its Application to Dark Matter-Nucleus Scattering
Bai-Shan Hu🇨🇳
The era of precision ab initio nuclear theory has arrived, enabling uncertainty-quantified predictions for nuclear structure and for interactions with external probes directly from the underlying nuclear force and electroweak currents. This review highlights recent breakthroughs that extend ab initio calculations to the heavy nucleus $^{208}$ Pb, to medium-mass systems with complex deformation, and to weakly-bound nuclei near the driplines. We also summarize ab initio calculations of nuclear responses for dark matter direct detection. Together, these advances demonstrate how ab initio methods can substantially reduce nuclear-physics uncertainties in searches for physics beyond the Standard Model, providing a more robust interpretation of current and forthcoming precision experiments.
Comments:
Accepted by Frontiers in Physics
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex)
arXiv:
2606.21032 [pdf]
Front.in Phys.(2026)·0 citations
02
[Submitted on 19 Jun 2026]
Level rearrangement in K- p system
T. Massimino🇺🇸 · N.V. Shevchenko🇨🇿 · Z. Papp🇺🇸 · J. Revai🇭🇺
We studied the level shifts in the $K^{-} p$ system caused by the interplay of strong nuclear and long range Coulomb potentials. We observed a level rearrangement in the system and found that the $1 s$ shift of kaonic hydrogen is in fact ``attractive''. In addition, we demonstrated that absorption in the strong antikaon-nucleon interaction does not destroy the level rearrangement.
Comments:
11 pages, 3 figures, 3 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.21261 [pdf]
0 citations
03
[Submitted on 19 Jun 2026]
Is the coexistence of strange quark stars and hadronic stars favored by astrophysical data? A Bayesian analysis
Luca Passarella🇮🇹 · Mirco Guerrini🇮🇹 · Giuseppe Pagliara🇮🇹 · Andrea Lavagno🇮🇹 · Alessandro Drago🇮🇹
Hadronic stars and strange quark stars could coexist within the so-called two-families scenario. In this respect, hadronic matter and strange quark matter correspond to two distinct equilibrium phases described by two different equations of state. We perform here the first detailed Bayesian analysis that makes use of astrophysical and laboratory data in order to constrain the equations of state adopted within the two-families scenario for hadronic and strange quark matter. In particular, in hadronic matter we consider the possible formation of hyperons and delta resonances (beside nucleons) within a class of non linear relativistic mean field models and in quark matter we consider the possible formation of a color-superconducting phase within a bag-like model. Results of the analysis indicate that while at the moment both the one-family and the two-families scenarios are compatible with the data, by comparing the Bayes factors of both models, the two-families scenario is favored with respect to the one-family scenario. Specifically, the two-families framework naturally relieves the tension between the intermediate-density softness of the equation of state required by small-radius objects and the high-density stiffness needed to support massive pulsars. Ultimately, future detections of even more massive compact objects, very compact ordinary-mass objects, or precise measurements of two distinct masses with the same radius, will provide strong indications in favor of the two-families scenario.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2606.21435 [pdf]
JHEAp(2027)·1 citation
04
[Submitted on 19 Jun 2026]
Microscopic mechanism of the Fayans pairing for the enhancement of charge radii
Tomoya Naito · Gianluca Colò · Xavier Roca-Maza · Hiroyuki Sagawa · Enrico Vigezzi
The Fayans energy density functional (EDF), and in particular its pairing sector, have been claimed to be able to reproduce the experimental data of charge radii in many instances. A particularly intriguing case is that of the $Ca$ isotopes between $A = 40$ and $48$ , where charge radii exhibit a "bell shape". In our work, we examine the microscopic origin of this behaviour. We prepare in total $25$ paramerizations of the Fayans-like pairing interaction, that are equivalent in fulfilling the same criteria for the reproduction of empirical pairing gaps. We find that both the density and the density-gradient dependence of the pairing interaction are important to reproduce the well-known enhancement of charge radii in the open-shell nuclei, leading to the "bell shape" behaviour of $Ca$ isotopes. In particular, this originates from the repulsive nature of the rearrangement potential, and cannot simply be mocked up by a refit of the pairing strength. At the same time, we notice some drawbacks of the Fayans standard EDFs, that may call for investigating a more general form of it.
Comments:
22 pages, 28 figures, 6 tables
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2606.21491 [pdf]
0 citations
05
[Submitted on 19 Jun 2026]
A short-range effective theory for single-neutron halo nuclei with a deformed core
Live-Palm Kubushishi · Daniel R. Phillips
We establish a short-range effective theory for deformed s-wave halos. The theory applies to a system in which neutrons are weakly bound to a core nucleus, and that core nucleus also exhibits a low-lying rotational band with a $0^{+}$ ground state and a first $2_{1}^{+}$ excited state. The effective theory then must have both halo degrees of freedom and degrees of freedom associated with rotation of the core. This leads to the particle plus rotor model of Bohr and Mottelson at leading order. We identify the relevant leading-order operators in the Hamiltonian that respect the symmetries of the system and the small parameters which define the effective theory's power counting. We carry out calculations for the $^{11}$ Be and $^{17}$ C systems in which we compute the low-lying positive-parity states of the core $+$ neutron systems up to the core $(2_{1}^{+})$ -neutron threshold. We do this for several different regulator parameters and establish that these energies can be renormalized using the leading-order set of operators. The spectrum is accurately described at leading order in both cases. Decay widths to d-wave core-neutron states have sizable cutoff dependence, but the Asymptotic Normalization Coefficients (ANCs) in $s$ -wave channels exhibit regulator dependence of a size consistent with next-to-leading-order effects. We also compute Coulomb breakup observables and compare with experimental data, finding leading-order results in reasonable agreement with data for both $^{11}$ Be and $^{17}$ C. The addition of one next-to-leading-order operator renders the ANCs of all s-wave states stable with respect to the regulator. It consequently also removes most of the 30\% variation of the leading-order Coulomb dissociation cross section with the regulator.
Comments:
22 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.21547 [pdf]
0 citations
06
[Submitted on 19 Jun 2026]
Electron scattering and the distribution of electric charge and magnetization inside nuclei
Alex Gnech · Lorenzo Andreoli · Graham Chambers-Wall · Garrett King · Saori Pastore
How are the electric and magnetic distributions carried by protons and neutrons arranged inside an atomic nucleus? One of the most reliable ways to answer this question is to scatter electrons from nuclei. Because the electromagnetic interaction is well understood and electron beams can be prepared and detected with high precision, electron scattering acts as a microscope that probes nuclear structure across a wide range of length scales. In this chapter we discuss how electron-nucleus scattering measurements are related to the distribution of the electric charge and magnetization inside nuclei, and what these distributions reveal about nuclear structure. We present this discussion through modern theoretical tools based on ab initio approaches, which describe nuclei as interacting many-body quantum systems, with many-nucleon interactions and electroweak currents derived from first principles.
Comments:
Invited contribution to the Encyclopedia of Nuclear Physics, 13 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.21576 [pdf]
0 citations
07
[Submitted on 19 Jun 2026]
One-Body and Two-Body Density Matrix Elements in a Symplectic Many-Body Basis
Jakub Herko (1 and 2) · Mark A. Caprio (1) ((1) Department of Physics and Astronomy, University of Notre Dame, (2) TRIUMF)
The symplectic no-core configuration interaction (SpNCCI) framework is an ab initio many-body method for nuclear structure which makes use of the approximate symplectic symmetry of nuclei by appropriate choice of many-body basis states. In this paper we derive recurrence relations allowing for calculation of one-body and two-body density matrix elements between the SpNCCI basis states. Availability of these matrix elements allows for integration of the SpNCCI framework with other modern many-body methods and for calculation of matrix elements of any one-body or two-body operator.
Comments:
25 pages, no figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.21598 [pdf]
0 citations
08
[Submitted on 19 Jun 2026]
Hyperonic equation of state for neutron stars: A systematic Bayesian comparison of density-dependent and non-linear relativistic mean-field models
Pedro Sanson🇵🇹 · Tuhin Malik🇵🇹 · Constança Providência🇵🇹
A systematic Bayesian inference study of the equation of state (EOS) of dense matter with strangeness is presented, extending five relativistic mean-field (RMF) models with both constant and density-dependent couplings to include the full baryon octet. The hyperon-nucleon couplings in the scalar channel are varied within ranges informed by hypernuclear data, while vector isoscalar couplings are fixed by the SU(6) symmetry quark model. Observational constraints from NICER (PSR J0030, J0437, J0740) and GW170817, theoretical constraints from chiral effective field theory ( $χ$ EFT) and perturbative QCD (pQCD), and experimental constraints from nuclear saturation properties are imposed simultaneously. We find that the inclusion of hyperons systematically reduces the maximum neutron star mass by $0.05$ - $0.10, M_{⊙}$ across all models while increasing the radius at $1.4, M_{⊙}$ by $0.5$ - $0.8$ km. The speed of sound exhibits a characteristic softening at densities $2$ - $3, ρ_{sat}$ coinciding with hyperon onset. All hyperonic models remain consistent with the $2, M_{⊙}$ constraint. Models with a more flexible isovector channel span a larger proton fraction when only nucleons are included. However, the extra flexibility is visibly suppressed by hyperons, meaning that the average proton distribution is independent of model flexibility when hyperons are included. Less flexible models show comparable or slightly increased proton fractions due to EOS stiffening when hyperons are included. Only a residual number of hyperonic equations of state give rise to a mass-radius curve with a negative slope at low masses. A $1.8, M_{⊙}$ neutron star with a radius larger than or similar to the radius of a $1.2, M_{⊙}$ star would provide strong evidence that the star contains baryonic degrees of freedom beyond nucleons.
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2606.21617 [pdf]
0 citations
09
[Submitted on 20 Jun 2026]
Nucleon Nucleon Potential Using N $3$ LO Chiral Effective Field Theory
Bassam A. Shehadeh
A microscopic description of nucleon-nucleon (NN) and nucleon-nucleus (NA) scattering is developed using chiral effective field theory (chiEFT) at next-to-next-to-next-to-leading order N3LO. The NN interaction is taken from the EGM formulation, which incorporates spectral function regularization Lambda-tilde to control short range components of the two pion exchange force, together with a Gaussian regulator Lambda to ensure convergence of the Lippmann-Schwinger (LS) equation. The regulator parameters (Lambda, Lambda-tilde) = (450, 500), (550, 600), (600, 600) MeV. The resulting chiEFT NN t-matrix is used to construct the first order optical potential, from which Wolfenstein amplitudes and elastic differential cross sections are calculated. The theoretical amplitudes (B) and (C) for pp and pn scattering at 100 and 200 MeV show good overall agreement with experimental data, with the largest discrepancies appearing in the small real component of the spin orbit amplitude. Calculations of p + 16O and p + 40Ca elastic scattering at 100 and 200 MeV reproduce the measured angular distributions with high accuracy, particularly at forward and intermediate angles. These results demonstrate that the EGM chiEFT potential provides a consistent and quantitatively reliable framework for describing NN observables and NA elastic scattering in the 100-200 MeV energy range, while highlighting the need for improved treatment of short range and spin dependent contributions at higher energies.
Comments:
12 pages and 8 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.22232 [pdf]
0 citations
10
[Submitted on 21 Jun 2026]
Multistage dynamical modeling of heavy-ion collisions
Lipei Du🇺🇸
Relativistic heavy-ion collisions create deconfined QCD matter whose properties must be inferred from final-state observables through dynamical modeling. This contribution discusses recent progress and open issues in multistage simulations, with emphasis on the connection between bulk evolution, conserved charges, strangeness, and heavy flavor. At RHIC Beam Energy Scan energies, the breaking of longitudinal boost invariance makes charge stopping and rapidity-dependent observables essential for constraining the finite-density medium. Strange hadrons are sensitive to the local chemical environment and conserved-charge correlations, while heavy flavor probes microscopic transport and hadronization. Combining these observables within multi-sector inference frameworks provides a path toward more robust constraints on the equation of state and transport properties of QCD matter.
Comments:
6 pages, 1 figure. Invited plenary talk at Strangeness in Quark Matter 2026 (Los Angeles, CA, USA, Mar 22-27, 2026). Contribution to the proceedings
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2606.22315 [pdf]
1 citation
11
[Submitted on 21 Jun 2026]
Full Configuration Interaction Quantum Monte Carlo for Accurate $Ab Initio$ Nuclear Structure Calculations
Rongzhe Hu · Furong Xu · Baishan Hu · Ali Alavi
We introduce novel full configuration interaction quantum Monte Carlo (FCIQMC) as an accurate many-body solver for $ab initio$ nuclear structure calculations. This stochastic approach directly samples the exact wave function in the full configuration space, enabling high-fidelity treatment of high-order many-body correlations in strongly interacting nuclear systems. Using interactions from chiral effective field theory, we have computed ground-state energies and charge radii of $^{4}$ He, $^{8}$ Be, $^{12}$ C and $^{16}$ O with sub-percent-level many-body uncertainties. These results establish FCIQMC as a stochastic full-configuration-space solver capable of treating systems beyond the reach of the conventional no-core shell model, and as an accurate benchmark for truncated many-body expansion methods.
Comments:
4 pages, 3 figures; comments are welcome
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2606.22341 [pdf]
1 citation
12
[Submitted on 21 Jun 2026]
Event-by-event fluctuations of elliptic flow in ultrarelativistic O+O collisions
Renata Krupczak🇩🇪 · Nicolas Borghini🇩🇪 · Hendrik Roch🇫🇮
We study O+O collisions at $s_{NN} = 5.36$ TeV within a fully three-dimensional $McDipper$ + $MUSIC$ model, which allows us to describe the experimentally measured dependence of charged hadron multiplicity on centrality and pseudorapidity. We show that the initial elliptical eccentricity is mainly driven by the fluctuations of the energy deposition and thereby varies considerably event-by-event within a fixed centrality class. This also holds for elliptic flow $v_{2}$ , whose origin in O+O thus differs from that in collisions of heavy nuclei. Using a decomposition of initial states in an average event and uncorrelated modes, we find that despite the large size of fluctuations we can reproduce the joint probability distribution of eccentricity and elliptic flow with a reasonable accuracy with only a small set of fluctuation modes.
Comments:
14 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2606.22558 [pdf]
0 citations
13
[Submitted on 22 Jun 2026]
Input-driven analysis in predicting nuclear charge radii using Monte Carlo dropout Bayesian neural network
Jia-Xin Liu · Zhen-Yan Xian · Yan Ya · Si-Ying Ma · Na Tang · Rong An
Nuclei charge radii play an essential role in understanding the fundamental interactions of finite quantum fermion systems. In this work, input-driven Bayesian neural network based on the Monte Carlo dropout approach has been built to characterize the systematic evolution of charge radii of nuclei with proton number $Z \geq 20$ and mass number $A \geq 40$ . The motivated underlying mechanisms have been introduced into the input structures, which contain pairing effect, isospin asymmetry degree, the correlations between the valence nucleons and valence holes for neutron and proton, quadrupole deformation parameter $β_{20}$ , and the local shape staggering phenomena of $^{181, 183, 185}$ Hg isotopes.In addition, shell quenching effect is also taken into account by incorporating the modified Casten factor $P^{*}$ into the input structure. The quadrupole deformation parameters $β_{20}$ derived from finite-range droplet model (FRDM), relativistic mean field (RMF) theory and Weizsäcker-Skyrme (WS) approach are employed to analyze the local variations of nuclear charge radii.The hyperparameter is adjusted automatically in the constructed model.The calibrated results give comparable root-mean-square deviations (RMSD) in the training and validation sets with various shape deformation inputs. The abrupt increase in charge radii around N=60 is well reproduced along Z=37-40 isotopic chains, but this trend is less pronounced along Z=36 and 41 chains. This provides a indicator to confirm the rapid shape-phase transition regions around N=60 from the perspective of finite nuclei size. Shell quenching effect of charge radii along the bismuth isotopes are reproduced well at N=126, but slight deviations can be encountered due to the absence of high-order octupole deformation around N=130 regions and shape-staggering phenomena toward neutron-deficient regions, respectively. This means that...
Comments:
28 pages, 5 figures, accepted by Nuclear Science and Techniques
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2606.22937 [pdf]
0 citations
14
[Submitted on 22 Jun 2026]
Exploring Pion-Induced High-Momentum Components in Nuclei via $(p, p^{'} π)$ Reactions
Junki Tanaka · Junichi Kato · Hiroshi Toki
Pion exchange plays a fundamental role in nuclear structure and is responsible for tensor correlations and high-momentum components in nuclei. The $(p, p^{'} π)$ reaction provides a unique opportunity to investigate pion dynamics under large-momentum-transfer conditions. Its three-body kinematics allows large momentum transfer to be achieved while keeping the excitation energy of the residual nucleus low. We investigate the kinematical properties of the $^{12} C (p, p^{'} π^{+})^{12} B$ reaction using Lorentz-invariant three-body phase-space calculations. The calculations were performed for a 392-MeV proton beam assuming a constant transition amplitude. The resulting momentum-transfer map and phase-space distribution identify experimentally accessible regions of large momentum transfer and provide guidance for optimizing a double-arm spectrometer experiment at RCNP. The present study establishes a model-independent kinematical foundation for future investigations of pion-induced correlations, high-momentum components, and pion dynamics in nuclei.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2606.23067 [pdf]
0 citations
15
[Submitted on 22 Jun 2026]
Scattering Observables from Few-Body Densities and Application in Light Nuclei
Alexander Long
The Transition Density Amplitude (TDA) method of Griesshammer et al. is applied to compute scattering observables for Compton scattering, threshold neutral pion photoproduction, and elastic pion scattering on the light nuclei Hydrogen 3, Helium 3, Helium 4, and Lithium 6. In this formalism the amplitude factorizes into an irreducible few-body kernel, which encodes the interaction of the probe with the active nucleons, and a transition density amplitude, which carries the nuclear structure information. Because the densities are computed once per nucleus and momentum transfer and then convolved with any process-specific kernel, the same nuclear input is reused across reactions, yielding substantial computational savings over direct evaluation. This factorization is realized in the publicly available Fortran suite DensityScattering, developed as part of the present work; a researcher implementing a new reaction need only supply the corresponding kernel in a prescribed format, with infrastructure for density handling, integration, quantum-number summation, and output already provided. The TDAs are constructed from nuclear wave functions using the semilocal momentum-space regularized chiral potential of Reinert, Krebs, and Epelbaum at cutoffs of 450 and 500 MeV. For Lithium 6, no-core shell model wave functions are evolved under a Similarity Renormalization Group (SRG) transformation; a back-transformation scheme ("SRG-And-Back"), co-developed for the present work, returns the densities to the physical momentum scale and thereby preserves the original chiral ordering. The induced uncertainty is validated against exact Helium 4 results at the 2% level, and convergence studies for Lithium 6 Compton scattering bound the residual uncertainty below 6%.
Comments:
Dissertation directed by Harald W. Griesshammer
Subjects:
Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
2606.23331 [pdf]
0 citations
16
[Submitted on 22 Jun 2026]
Ultra-Peripheral Collisions as a Nuclear-Structure Interferometer with Interpretable Multitask Deep Learning
Jing-Zong Zhang🇨🇳 · Wang-Mei Zha🇨🇳 · Lingxiao Wang🇯🇵 · Guo-Liang Ma🇨🇳
Precise knowledge of nuclear structure is essential across fundamental physics, yet probing these structures is notoriously difficult. To address this challenge, ultra-peripheral collisions (UPCs) provide a femtoscopic tomography for imaging the atomic nucleus. UPCs offer a pristine electromagnetic pathway: coherent vector-meson photoproduction generates patterns of diffraction and two-source interference that directly encode the nuclear spatial density. Turning these patterns into quantitative constraints is, however, a challenging inverse problem, complicated by correlated sensitivities to deformation and neutron skin, phase smearing, and experimental backgrounds. Here we introduce an interpretable Multitask deep-learning framework that maps transverse momentum distributions to multiple nuclear-structure indicators simultaneously and identifies the kinematic regions driving each inference. We demonstrate the approach with coherent $J / ψ$ photoproduction in $_{40}^{96} Zr +_{40}^{96} Zr$ collisions, showing that the learned features separate diffraction-dominated and interference-dominated information and provide analysis-ready observables for future high-luminosity data.
Comments:
14 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th); Machine Learning (cs.LG); Nuclear Experiment (nucl-ex); physics.optics (physics.optics); Quantum Physics (quant-ph)
arXiv:
2606.23353 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE