Nuclear Theory·nucl-th

Monday·June 8, 2026

12 papers—6 primary·6 cross-listed

01
Microscopic formulation of the interacting boson-fermion model using the nuclear energy density functional
M. Homma · K. Nomura
Microscopic modeling of low-energy spectroscopy in medium-heavy and heavy odd- $A$ nuclei is an outstanding open problem in nuclear physics. We propose a novel spectra-generating collective model for odd- $A$ nuclei constructed by means of the nuclear energy density functional theory and the interacting boson-fermion model. The bosonic Hamiltonian for an even-even nucleus, which is treated as a core, and the strength parameters for the interactions between the core and an odd nucleon are completely determined by using as microscopic inputs the potential energy curves and deformed single-particle spectra obtained from the self-consistent mean-field calculations. In applications to odd- $A$ Eu, Sm, La, and Ba isotopes, we demonstrate the validity of the proposed method in reproducing reasonably the observed low-energy spectra and shape phase transitions in the general cases of the quadrupole collective states, that is, nearly spherical, strongly deformed, and $γ$ -soft shapes, in the presence of an odd nucleon in a single- $j$ orbit.
nucl-thnucl-exPRC(2026)·0 citations
02
Solution of the Equation-of-Motion Phonon Method eigenvalue problems on the D-Wave quantum annealer
C. De Lucia🇮🇹 · A. Martone🇮🇹 · F.A. D'Aniello🇮🇹 · A. Mastroianni🇮🇹 · G. Nunziata🇮🇹 · G. De Gregorio🇮🇹 · R. Folprecht🇨🇿 · F. Knapp🇨🇿 · N. Lo Iudice🇲🇽 · P. Vesely🇨🇿
The solution of large-scale eigenvalue problems is crucial in nuclear many-body theory, where Hamiltonian matrices often reach extremely large dimensions. Quantum computing opens new perspectives for addressing such demanding problems. Although the Quantum Phase Estimation algorithm offers, in principle, a systematic route to matrix diagonalization, its practical deployment demands levels of coherence and error correction that current quantum hardware cannot yet support. A viable near-term strategy is instead to exploit quantum annealing, which enables the recasting of eigenvalue problems into quadratic unconstrained binary optimization formulations that can be addressed by existing annealing-based processors. Here, we propose a hybrid quantum-classical algorithm that combines quantum annealing and classical deflation to iteratively extract the full eigenspectrum of both standard and generalized eigenvalue problems. We benchmark this method on eigenvalue problems arising from the Equation of Motion Phonon Method performing calculations on real quantum hardware. Our approach illustrates the capabilities and limitations of near-term quantum devices in addressing nuclear eigenvalue problems.
nucl-thquant-phPRC(2026)·0 citations
03
External-Field-Assisted Muon Reactivation in Muon-Catalyzed Fusion: A Rate-Network Criterion for Reducing Alpha Sticking
Wei Kou · Xurong Chen
Alpha sticking is a major loss channel in deuterium--tritium muon-catalyzed fusion. We study whether an additional external-field-assisted stripping channel can reduce the residual sticking loss after conventional collisional reactivation. The external contribution is written as $R_{X} = f_{X} P_{X} η_{X}$ , where $f_{X}$ is the space--time overlap between the external field and the residual stuck $(α μ)^{+}$ population, $P_{X}$ is the microscopic stripping probability, and $η_{X}$ is the probability that the stripped $μ^{-}$ is returned to the $d μ / t μ \to d t μ$ fusion cycle before escape or decay. This gives $ω_{S}^{eff} = ω_{S}^{0} (1 - R_{col}) (1 - R_{X})$ and leads directly to a probability-level no-go condition, $η_{X}^{crit} > 1$ , for any target improvement requiring more recycling than is probabilistically available. We construct an energy-resolved post-stripping rate network including slowing down, atomic capture, free escape, muon decay, atomic-stage loss, ordinary molecular formation, and an effective resonant $d t μ$ channel. Benchmark scans show that the useful regime is a transport window: the stripped muon must be confined and recycled efficiently. With the reference inputs used here, the best-performing scenario increases the cycle yield from $N_{fus, μ} = 112.6$ in the collision-only case to $N_{fus, μ} = 156.5$ . Resonant molecular formation suppresses atomic-stage loss and broadens the high-recycling region, but it cannot compensate for prompt escape or poor field--population overlap. The rate network therefore identifies the transport and overlap conditions required for external-field-assisted reactivation to reduce residual alpha sticking.
nucl-th1 citation
04
Impact of Shape Coexistence on Nuclear Stability
G. Saxena · H. Sikhwal · N. Chandnani · Pranali Parab · Siddharth Parashari · Gabriela Llosá · Mamta Aggarwal
Nuclear decay properties are conventionally predicted assuming nuclei decay from their ground-state configurations. However, this often neglects a fundamental structural complexity which is the phenomenon of shape coexistence, where nuclei possess multiple competing configurations at nearly degenerate energies. When both parent and daughter nuclei can exist in different energy minima, multiple decay pathways become possible. We systematically investigate how shape coexistence influences nuclear decay for approximately 1500 even-even nuclei ( $8 \leq Z \leq 118$ , $8 \leq N \leq 184$ ) using the Nilsson-Strutinsky method and relativistic mean-field calculations with NL3 $^{*}$ , DD-ME2, and DD-PC1 functionals. We identify around 400 nuclei exhibiting competing energy minima separated by less than 1 MeV. For these shape-coexisting nuclei, we calculate $α$ , $β^{+}$ and $β^{-}$ decay half-lives considering all possible transition pathways between the competing minima. Our results demonstrate that shape coexistence substantially impacts decay predictions, with half-lives showing variations up to nearly one logarithmic unit depending on which configurations participate in the transition. Comparison with experimental data from NUBASE2020 shows that pathways involving the second minimum sometimes reproduce measured lifetimes more closely than conventional ground-state to ground-state assumptions. Branching ratios exhibit even stronger sensitivity, with certain nuclei displaying complete inversions of the dominant decay mode depending on configuration choice. These pathway-dependent variations are not due to model uncertainties but reflect inherent structural effects. The correlation between the shape dynamics and nuclear stability establishes the shape coexistence as an essential component in predictive nuclear structure and astrophysics studies.
nucl-thPLB(2026)·0 citations
05
Probing exotic multi-proton emitters: A Gamow shell model study of proton-rich fluorine and neon isotopes beyond the drip line
N. Chen · J. G. Li · M. R. Xie · P. Y. Wang · K. H. Li · Q. Yuan · N. Michel
We investigate proton-rich systems beyond the proton drip line, focusing on the notably poorly known 13F and 15Ne and the yet unobserved 14Ne, whose structure properties remain weakly constrained. Using the Gamow shell model (GSM), which consistently incorporates both inter-nucleon correlations and couplings to the particle continuum, we study oxygen, fluorine, and neon isotopes with mass A=12-16. Taking 8C as an inert core, the GSM Hamiltonian based on an effective field theory nucleon-nucleon interaction is optimized for this proton-rich region. The constructed Hamiltonian reproduces the low-lying spectra and decay properties of fluorine and neon isotopes beyond the proton drip line. We quantify many-body configuration and average partial-wave occupancies to elucidate the structural evolution of the drip line nuclei 12-14O, 13-15F, and 14-16Ne. In particular, multi-proton separation energies and spectroscopic factors are analyzed in detail, leading to a prediction for the unresolved ground state of 13F. Furthermore, the candidate 4p emitter 14Ne is theoretically predicted for the first time, providing valuable guidance for future experimental investigations.
nucl-thPLB(2026)·1 citation
06
Proton and Neutron Elastic Scattering on He Targets from $Ab Initio$ SA-NCSM Optical Potentials
Darin C. Mumma · Matthew B. Burrows · Kristina D. Launey · Daniel Langr · Tomas Dytrych
We construct and discuss $ab initio$ nucleon-nucleus optical potentials at low energies for $^{3, 4, 6}$ He targets. In this work, we use the $ab initio$ SA-NCSM/GF approach that combines the $ab initio$ symmetry-adapted no-core shell model with the Green's function technique to construct optical potentials, and extend this formulation to proton scattering and targets with nonzero spin. We show that these optical potentials reproduce experimental differential cross sections and phase shifts for proton and neutron elastic scattering remarkably well. The $ab initio$ SA-NCSM/GF approach provides nonlocal, energy dependent and dispersive optical potentials, suitable for the astrophysically relevant regime of low energies and for exotic nuclei, where experiments are difficult and data is often unavailable.
nucl-th0 citations
07
Hyperon-Nucleon Spectrometer
Xiaozhi Bai · Xu Cao · Zhe Cao · Jinhui Chen · Kai Chen · Qibo Chen · Shi Chen · Xin Chen · Yuquan Chen · Zhenyu Chen · Jianping Dai · Heng-Tong Ding and 228 other authors
Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding $Λ$ polarization puzzle, in which $Λ$ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton ( $pp$ ), proton-nucleus ( $p A$ ), and nucleus-nucleus ( $AA$ ) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of $p A$ and $AA$ collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.
↳ physics.ins-dethep-exhep-phhep-th+22 citations
08
Radial Oscillations of Viscous Stars at Finite Temperature
Amanda Guerrieri🇧🇷 · Gabriel S. Rocha🇧🇷 · Gabriel S. Denicol🇧🇷 · Raissa F. P. Mendes🇧🇷
We study the radial oscillation spectrum of relativistic stars within Israel-Stewart and Navier-Stokes theories, extending previous analyses to include heat diffusion and a thermodynamically consistent finite-temperature equation of state. The inclusion of heat flux gives rise to a distinct thermal sector in the mode spectrum, whose structure closely mirrors the dispersion relations of an infinite dissipative fluid. Within Israel-Stewart theory, the thermal modes transition from purely damped to propagating behavior above a critical overtone number, providing a finite-size realization of relativistic second sound in compact stars. Remarkably, the finite stellar geometry can push even the fundamental thermal mode into the propagating regime -- a feature with no continuum analogue. For the class of equations of state considered here, where finite-temperature corrections enter as controlled, Sommerfeld-type perturbations of a cold polytrope, the thermal sector couples only weakly to the ordinary fluid oscillation spectrum, with the coupling being of second order in a suitable temperature parameter. We further show that the discrete stellar spectrum is well captured by an analytic ansatz constructed from the flat-spacetime dispersion relations, with the star's finite radius discretizing the continuous mode structure. Our results complete the analysis of radial oscillations of viscous stars by incorporating the last remaining dissipative degree of freedom within the Israel-Stewart framework.
↳ gr-qcnucl-th1 citation
09
Lepton interactions from GeV to EeV
Reinaldo Francener🇧🇷
In this work, we investigate the phenomenological consequences of neutrino and muon interactions with matter. In our studies, we focused in phenomenological predictions for two experiments: FASER and IceCube. FASER is a detector located at the LHC that measures neutrinos produced in proton-proton collisions. A new version of FASER, FASER2, has been proposed to operate in the Forward Physics Facility during the high-luminosity regime of the LHC. The intense flux of tau neutrinos expected at FASER2 motivated us to study the polarization effects of the tau produced in charged current interactions. Our results show that the produced taus will not be completely polarized. Among the Standard Model particles, only neutrinos and muons produced in proton-proton collisions at the LHC can reach FASER. In our study, we show that muon-initiated events can reveal interesting nucleon properties, such as nuclear effects and the existence of an intrinsic charm. The high number of events induced by neutrinos at FASER motivated us to study rare processes in neutrino interaction, such as the neutrino trident. Our results indicate that the neutrino trident process can be observed at FASER2. We have also studied muon trident at the LHC, and we showed that tau pair production can be observed for the first time in this reaction. In contrast to neutrinos detected at the LHC, the neutrinos observed at IceCube come from natural sources, being mainly atmospheric and astrophysical neutrinos. IceCube is capable of observing neutrinos across a wide energy spectrum, ranging from a few GeV to beyond PeV. We show that the study of these events can contribute to our understanding of the structure of target hadrons, as well as the search for physics effects beyond the Standard Model in the propagation of these neutrinos in the universe until they reach the Earth.
↳ hep-phastro-ph.HEhep-exnucl-th0 citations
10
Product units in gated recurrent units improve nuclear-mass prediction
Ziyuan Li · Paulo S.A. Freitas · John W. Clark · Babette Dellen
The prediction of masses of atomic nuclei using machine learning can complement theoretical models and advance the exploration of poorly known domains of the nuclear chart. We propose a machine learning technique based on gated recurrent units (GRU), which have demonstrated competitive performance in nuclear-mass prediction by exploiting long-term dependencies. By integrating multiplicative interactions and product-unit transformations within recurrent units, we report significant improvements in nuclear-mass prediction. Computations are performed in the complex domain to jointly capture amplitude and phase dynamics. For interpolation and temporal-extrapolation tasks based on the atomic mass evaluation (AME2016 and AME2020), the complex additive-multiplicative product-unit gated recurrent unit (AM-PU-GRU) model consistently achieves the lowest prediction errors, with an interpolation RMSE of 0.227 $\pm$ 0.004 MeV and an extrapolation RMSE of 0.179 $\pm$ 0.015 MeV. These results surpass other state-of-the-art machine learning models and also outperform the real-valued GRU baseline and product-unit ablation variants, while remaining robust to different theoretical priors, including WS4 and SEMF. Our findings establish complex-valued product-unit recurrent networks as a new benchmark for sequence-based nuclear-mass prediction.
↳ cs.LGnucl-thIn: Lecture Notes in Computer Science, Sp…·0 citations
11
Measurement of energy-level splitting from Charge-Symmetry Breaking in $A$ = 4 mirror hypernuclei
STAR Collaboration
Breaking of fundamental symmetries is a ubiquitous phenomenon in physics, underlying the origin of mass and the emerging structure in the universe. The charge symmetry of $Λ$ hyperon-nucleon interactions can be probed through the difference in the $Λ$ binding energy ( $B_{Λ}$ ) between mirror hypernuclei. In this paper, the $B_{Λ}$ of mirror hypernuclei with atomic mass number $A$ = 4, $_{Λ}^{4} H$ and $_{Λ}^{4} He$ , are measured in Au+Au collisions at the center-of-mass energy of $s_{NN}$ = 3 GeV with the STAR experiment at RHIC. For the ground states, we obtain $B_{Λ}$ ( $_{Λ}^{4} H$ ) = 2.24 $\pm$ 0.02 (stat.) $\pm$ 0.04 (syst.) MeV and $B_{Λ}$ ( $_{Λ}^{4} He$ ) = 2.39 $\pm$ 0.05 (stat.) $\pm$ 0.05 (syst.) MeV, yielding a charge-symmetry breaking (CSB) effect at the level of 0.15 $\pm$ 0.05 (stat.) $\pm$ 0.04 (syst.) MeV. In combination with previous measurements of $γ$ -ray transitions from their $1^{+}$ excited states, the CSB in excited states is determined to be $-$ 0.17 $\pm$ 0.05 (stat.) $\pm$ 0.04 (syst.) MeV. These measurements provide a precise determination of CSB in the hypernuclear system, and establish that the $Λ$ binding energy differences in ground and excited states are comparable in magnitude but opposite in sign, offering new insight to the CSB effect in $Λ$ -nucleon interactions.
↳ nucl-exnucl-th1 citation
12
Mechanical distribution of the pseudoscalar charmonium and bottomonium on the light-front
Ashutosh Dwibedi🇮🇳 · Satyajit Puhan🇹🇼 · Sabyasachi Ghosh🇮🇳
We investigate the energy-momentum tensor of pseudoscalar charmonium and bottomonium within the framework of the light-front quark model. The gravitational form factors (GFFs), namely the $A$ and $D$ -terms, are evaluated in terms of the light-front wave functions. The corresponding spatial mechanical distributions in the transverse plane are obtained through the Fourier transform of these GFFs. To examine the sensitivity of the results to the internal quark-antiquark distribution inside the meson, two distinct Gaussian forms are employed for the spatial part of the wave function. We analyze several mechanical properties in the transverse plane, including the momentum density, pressure distribution, shear stress, force density, and internal energy density. The pressure distribution exhibits a node where it changes sign from positive (repulsive) to negative (attractive) with increasing transverse distance. The force distribution remains positive throughout the transverse plane, supporting the stability condition proposed in earlier studies. Most of the spatial distributions, except for the shear stress, are found to be sensitive to the choice of the spatial wave function near the center of the meson, while they become nearly insensitive toward the periphery. In contrast, the shear stress distribution exhibits noticeable sensitivity to the choice of wave function in the intermediate transverse region.
↳ hep-phnucl-th3 citations

Affiliations

first authorsco-authorsvia INSPIRE