Nuclear Theory·nucl-th

Tuesday·June 2, 2026

19 papers—10 primary·9 cross-listed

01
Coupled nuclear and leptonic longitudinal collective modes in neutron star matter : a covariant Vlasov approach
Aziz Rabhi · Olfa Boukari · Sidney S. Avancini · Constança Providência
A covariant relativistic approach based on the Vlasov equation is used to study collective modes in neutron-star matter. The analysis is carried out within relativistic mean-field models describing charge-neutral and $β$ -equilibrated matter composed of neutrons, protons, electrons, and muons. We investigate the conditions under which nuclear collective excitations couple to electron and muon plasmon modes, a phenomenon relevant for neutron stars and supernova matter. The study is undertaken considering relativistic mean field models with different isoscalar and isovector properties. It is shown that the nuclear-leptonic coupling can be sufficiently strong to modify the onset of nuclear collective modes and to affect their isoscalar or isovector character.
nucl-thastro-ph.HE0 citations
02
Examination of the $α$ -cluster breaking in the four $0^{+}$ bands of $^{12}$ C with the variation of multiple bases of the antisymmetrized molecular dynamics
Takayuki Myo
I investigate $^{12}$ C, particularly the four kinds of the $0^{+}$ bands with various types of the $3 α$ configurations. These states are obtained in the variation of the multiple bases of the antisymmetrized molecular dynamics, where the bases are optimized simultaneously in the variation of the total energy. In the $0_{2}^{+}$ Hoyle state and the $0_{3}^{+}$ linear-chain state, I confirm a mixture of the $α$ -cluster breaking of the $s$ -wave configuration with contributions from the spin-orbit force, while the $0_{4}^{+}$ state exhibits a relatively pure $3 α$ cluster state characterized by a large radius. The $2_{2 - 4}^{+}$ and $4_{2 - 4}^{+}$ states also tend to be the pure $3 α$ cluster states. The monopole transitions between the $0_{2}^{+}$ and $0_{4}^{+}$ bands exhibit large values, suggesting breathing mode of the $3 α$ states in the $0_{4}^{+}$ band. This conclusion aligns with the predictions of the $3 α$ models with an $α$ condensate and also with a neural network, although the order of the $0_{3}^{+}$ and $0_{4}^{+}$ bands is reversed in the present results due to the attraction of the spin-orbit force.
nucl-thnucl-exPRC(2026)·0 citations
03
Shape evolution of krypton isotopes calculated with axially deformed relativistic Hartree-Bogoliubov approach
Zi Xin Liu · Yi Hua Lam · Peter Ring
We perform a systematic study of the structure and properties of the krypton isotopic chain including both even-even and odd- $A$ nuclei based on the axially deformed relativistic Hartree-Bogoliubov approach. Five effective interactions of three families of covariant density functionals, i.e., PC-L3R, DD-PCX, DD-PC1, DD-MEX, and DD-ME2, are employed to calculate potential energy surfaces of krypton isotopes. $^{74, 75}$ Kr and $^{90, 91, 92}$ Kr are determined as typical candidates of shape coexistence. The potential surfaces originating from the PC-L3R, DD-PCX, and DD-MEX interactions exhibit an abrupt shape transition from oblate to prolate for $^{73 - 74}$ Kr, whereas DD-PC1 and DD-ME2 preserve an oblate ground-state shape. Such discrepancies are attributed to the occupations of single-particle levels at the vicinity of the Fermi surface described by these functionals. Moreover, the comparison between spherical and deformed calculations verifies the indispensability of deformation degrees of freedom in this region. The consideration of deformation effects improves the description of two-neutron separation energies, of which its evolution clearly demonstrates the $N = 50$ and $82$ shell closures. Interestingly, PC-L3R predicts a more extended two-neutron drip line up to $^{132}$ Kr, in agreement with the NL3* and PC-PK1 nonlinear effective interactions, whereas other functionals estimate a rather short isotopic chain up to $^{119}$ Kr. This anomalous extension implies a significant softening or even collapse of the traditional $N = 82$ shell closure near the neutron-rich drip line, highlighting the need for future studies based on triaxial deformation and beyond-mean-field correlations in this nuclear region.
nucl-thnucl-ex0 citations
04
A semi-classical study of muon-enhanced proton-boron-11 fusion
Hong-Yi Wang · Ming-Yu Chen · Hao-Le Ma · Zhu-Fang Cui
A recent theoretical study has suggested that muons can enhance proton-boron-11 (p- $^{11}$ B) reaction cross-section by several orders of magnitude in the low-energy regime. In this work, we investigate this reaction process using a semi-classical treatment, that is, a muon and a proton first form a muonic hydrogen atom p $μ$ , which subsequently collides with a $^{11}$ B nucleus. During the collision, the p $μ$ atom approaches the $^{11}$ B nucleus and is then repelled by the Coulomb repulsive potential. At the distance of closest approach between the proton and the $^{11}$ B nuclei in this classical scattering process -- namely, the classical turning point -- quantum tunneling through the Coulomb barrier can occur, allowing the proton to penetrate into the range of the nuclear force of the $^{11}$ B and trigger the fusion reaction. We determine the turning point statistically by using the classical trajectory Monte Carlo method, where the initial phase-space distributions of the proton and muon are sampled from the ground-state microcanonical distribution. Our results show that, compared with the bare-nucleus case, the reaction cross-section is enhanced by several orders of magnitude in the low-energy region. A comparison with the static charge-shielding treatment reveals certain differences; however, both approaches demonstrate that the catalytic effect of the muon can significantly enhance the low-energy p- $^{11}$ B reaction cross-section.
nucl-thnucl-exphysics.plasm-ph0 citations
05
Quantum dominance of coherent bremsstrahlung in $^{124}$ Sn + $^{124}$ Sn scattering at 25 MeV/u
Sergei P. Maydanyuk (1 and 2)🇨🇳 · Ju-Jun Xie (1, 3 and 4)🇨🇳 · Peng-Ming Zhang (5)🇨🇳 · Li-Ping Zou (6) ((1) Southern Center for Nuclear-Science Theory (SCNT), Institute of Modern Physics, Chinese Academy of Sciences, Huizhou 516000, China, (2) Institute for Nuclear Research, National Academy of Sciences of Ukraine, Kyiv 03680, Ukraine, (3) Heavy Ion Science and Technology Key Laboratory, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China, (4) School of Nuclear Sciences and Technology, University of Chinese Academy of Sciences, Beijing 101408, China, (5) School of Physics and Astronomy, Sun Yat-Sen University, Zhuhai 519082, China, (6) Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen University, Zhuhai 519082, China)🇨🇳
We present quantum-mechanical calculations of bremsstrahlung in the $^{124}$ Sn + $^{124}$ Sn at 25 MeV/u reproducing the measured photon spectrum over the full energy range. For the first time, we quantitatively determine the incoherent-to-coherent ratio in the photon spectrum. This ratio is extremely small, ranging from $1 0^{- 11}$ to $1 0^{- 4}$ , which demonstrates that coherent emission dominates throughout the measured energy range. This behavior is in sharp contrast to proton-nucleus scattering, where incoherent emission dominates because of the leading role of nucleon magnetic moments. This contrast is illustrated by the TAPS Collaboration data for $p +^{197} Au$ collisions at a proton beam energy of 190 MeV, where the corresponding ratio reaches $1 0^{3}$ - $1 0^{5}$ . We find that incoherent-to-coherent ratios explain the difference between the two spectra in unified picture: (1) In proton--nucleus scattering, the spectrum contains a pronounced hump, (2) In $^{124}$ Sn + $^{124}$ Sn scattering, the spectrum decreases monotonically and has a nearly logarithmic shape. Our results identify a previously unexplored quantum regime of bremsstrahlung emission in nuclear reactions and open a new route for studying coherent effects in heavy-ion collisions.
nucl-thhep-phhep-thnucl-ex0 citations
06
Hydrodynamics without a relaxation gap: memory effects, nonlocality, and superdiffusion
Lorenzo Gavassino🇬🇧 · Sukanya Mitra🇮🇳 · Rajeev Singh🇷🇴
By studying a simple model of relativistic particles propagating through a background medium with an energy-dependent relaxation time that is unbounded from above, we investigate how long-term memory obstructs the emergence of local hydrodynamics in systems with a gapless non-hydrodynamic sector. In the RTA matching frame, we show that the full gradient expansion is generically divergent in most flows, even for Fourier modes, and that any resummation necessarily retains an infinite set of slow non-hydrodynamic degrees of freedom. The divergence of the gradient expansion therefore reflects a more fundamental breakdown of hydrodynamic locality caused by persistent non-hydrodynamic memory. We finally show that sufficiently singular relaxation spectra can invalidate ordinary diffusion itself. In these regimes, the diffusivity diverges, and the late-time dynamics become superdiffusive, governed by intrinsically nonlocal constitutive relations.
nucl-thhep-thPRD(2026)·0 citations
07
Radial-flow fluctuations in the geometrical-scaling framework
Takeshi Osada🇯🇵
We discuss radial-flow fluctuations using the $p_{T}$ -differential measure $v_0(p_{\rm T})$, together with its $p_{T}$ -integrated counterpart $v_0$, within the framework of geometrical scaling (GS), where the saturation momentum scale provides the characteristic scale for particle production. We show that the GS framework leads to results similar to those obtained from the momentum-rescaling model proposed by Jiangyong Jia. In the GS picture, event-by-event spectral fluctuations are governed by fluctuations of the saturation momentum scale; consequently, the single-mode ansatz introduced in Jia's model emerges naturally. We also show that the GS picture suggests a possible connection between transverse-momentum correlations and fluctuations of the emission region, which may be probed through Hanbury Brown and Twiss (HBT) analyses. Using the string percolation model, which is closely related to GS, we estimate the multiplicity dependence of radial-flow fluctuations and propose the scaled quantity $A_{0} (N_{Δ y}) \equiv v_{0}^{2} N_{Δ y}$ , with $N_{Δ y} = (d N / d y) Δ y$ , as a diagnostic observable for testing the role of effective flux-tube fluctuations.
nucl-thhep-ph1 citation
08
Hypernucleus production in p+Au reactions at the FAIR facility
Nitikorn Jaingarm🇹🇭 · Pornrad Srisawad🇹🇭 · Christoph Herold🇹🇭 · Ayut Limphirat🇹🇭 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪
We explore the production of hypernuclei in p+Au reactions using the UrQMD model accompanied by a standard phase space coalescence model. We focus on the proton beam energy range of $E_{lab} = 5 - 30$ GeV as this energy range will be investigated by the CBM-experiment at the upcoming FAIR facility. Starting from proton, $Λ$ , $Σ$ , $Ξ$ and $Ω$ production, we predict the yields, rapidity and transverse momentum distributions of $_{Λ}^{3} H$ , $_{Λ}^{4} H$ , $Ξ$ N and $Ξ$ NN hypernuclei. We conclude that the production rates of novel multi-strange hypernuclei are well within the reach of the CBM-experiment.
nucl-thhep-phnucl-ex0 citations
09
The spectrum of $^{18}$ O in terms of the multiconfigurational dynamical symmetry
Gábor Riczu · Chandra Sekhar Panda · Géza Lévai · József Cseh
Background: The experimental study of the $^{6}$ Li-transfer reaction and alpha-scattering resulted in a rich spectrum of $^{18}$ O, including some strong indication for band structure. Different configurations are proposed for the structural interpretation of different energy domains. Purpose: We intend to investigate whether a uniform description is possible for the complete spectrum, including the high-lying states from scattering measurement. Methods: We apply the multiconfigurational dynamical symmetry for the determination of the shape isomers and for the calculation of the spectrum obtained from different reactions. Results: The shape isomers of $^{18}$ O is obtained from the study of the stability and self-consistency of the SU(3) symmetry, which is in the intersection of the shell and different cluster configurations. The $^{14}$ C+ $^{4}$ He spectrum is calculated, and its connection to other configurations is revealed. A very simple Hamiltonian is applied, including only a harmonic oscillator term, a quadrupole interaction and an $L^{2}$ term. Conclusions: The spectrum (from the ground state up to the high-lying states) can be reasonably well described by a $^{14}$ C+ $^{4}$ He cluster configuration. All the state allows the $^{12}$ C+ $2 n$ + $^{4}$ He clusterization as well, and has definite shell model content. For the lowest-lying three bands the shell configuration is unique, and the overlap of the shell and the different cluster configurations is 100%.
nucl-th0 citations
10
Quantum Symmetry Restoration and Emergent Effective Deformation in Relativistic Heavy-Ion Collisions
Hao-jie Xu🇨🇳 · Qun Wang🇨🇳
Classically deformed nuclear geometries are commonly employed in standard descriptions of relativistic collisions between two even-even nuclei, despite the fact that their exact ground states are rotationally invariant $0^{+}$ states. In this paper, we formulate the collision geometry directly from the eikonal scattering matrix based on a nonorthogonal Generator Coordinate Method construction of rotationally invariant ground states. In the optical limit, using a localized transported-density approximation for the collision-channel one-body response, rotational overlap localization generates an effective one-body density associated with the scattering process. Within this approximation, using the Gaussian Overlap Approximation and its heat-kernel representation, we show that rotational symmetry restoration acts as a geometric low-pass filter which exponentially suppresses effective deformation modes. The classical rigid-rotor limit is recovered for large intrinsic angular momentum fluctuations. We establish a microscopic framework connecting rotational symmetry restoration, collective overlap localization, and the effective deformation geometries of nuclei in high energy collisions.
nucl-thnucl-ex0 citations

Affiliations

first authorsco-authorsvia INSPIRE