Nuclear Theory·nucl-th

Monday·February 16, 2026

11 papers—6 primary·5 cross-listed

01
Low-energy $^{3}$ He( $α, γ$ ) $^{7}$ Be reaction within the Skyrme potential framework
Nguyen Le Anh · Nguyen Gia Huy · Dao Nhut Anh · Do Huy Tho · Hoang Thai An
\textbf{Background:} The $^{3}$ He( $α, γ$ ) $^{7}$ Be reaction plays a crucial role in the proton-proton chain and Big Bang nucleosynthesis, affecting solar neutrino fluxes and primordial element abundances. Experimental data at astrophysical energies remain uncertain due to the extremely low cross sections. \\ \textbf{Purpose:} This work uses a microscopic potential-model approach to construct the $^{3}$ He+ $α$ potential from the nucleon+ $α$ interaction, aiming to describe low-energy elastic scattering and to calculate the astrophysical $S$ factor of the $^{3}$ He( $α, γ$ ) $^{7}$ Be reaction. \\ \textbf{Method:} The nucleon-nucleus potential is derived from self-consistent Skyrme Hartree-Fock (HF) calculations extended to the continuum. The $^{3}$ He+ $α$ potential is then obtained by folding the HF potential with the $^{3}$ He density. A small number of scaling parameters is constrained by elastic-scattering data.\\ \textbf{Result:} The scaled Skyrme HF potential and folded potential simultaneously reproduce the low-energy $p$ + $α$ and $^{3}$ He+ $α$ $s$ -wave phase shifts, respectively. The calculated astrophysical $S$ factor of $^{3}$ He( $α, γ$ ) $^{7}$ Be shows good agreement with experimental data, yielding the recommended value $S_{34} (0) = 0.610 \pm 0.024$ ~keV~b. A moderate sensitivity of $S_{34} (0)$ to the choice of projectile density is also observed in the folding procedure. \\ \textbf{Conclusion:} The Skyrme HF-based potential provides a unified and predictive microscopic framework for describing both elastic scattering and radiative capture in light nuclei.
nucl-thPRC(2026)·0 citations
02
Dark matter effects on the properties of hybrid neutron stars
Jin-Biao Wei🇨🇳 · G. Wu🇨🇳 · H. Chen🇨🇳 · G. F. Burgio🇮🇹 · H.-J. Schulze🇮🇹
We study the effects of dark matter on the properties of hybrid neutron stars, in particular the influence on the mass-radius relation, the value of the maximum mass, and the hadron-quark phase transition. To single out the equilibrium configurations of dark-matter-admixed hybrid neutron stars (DHSs), we also study their radial oscillations. Both the stellar structure equations and the radial oscillation equations are solved for the two-fluid system, where the ordinary matter component and dark matter component couple only through gravity. For the ordinary matter components, we adopt the Brueckner-Hartree-Fock method for nuclear matter, and the Dyson-Schwinger or the field-correlator model for quark matter. For the dark matter component, we use a non-self-annihilating self-interacting fermionic model. We find that the presence of dark matter in DHSs leads to a decrease of the critical mass of the hadron-quark phase transition, a related possible onset of quark matter in dark-matter accreting stars, and a significant reduction of radial oscillation frequencies.
nucl-thastro-ph.HEPRD(2026)·2 citations
03
Chiral symmetry restoration and hyperon suppression in neutron stars
Bikai Gao🇯🇵
The ``hyperon puzzle'' remains a fundamental challenge in nuclear astrophysics. We investigate hyperon emergence in neutron star matter using the $S U (3)$ parity doublet model with chiral representation $(3, 3 ˉ) + (3 ˉ, 3)$ . This framework naturally incorporates chiral symmetry restoration and provides a systematic description of baryon masses in dense matter through the interplay between the chiral condensate and the chiral invariant mass $m_{0}$ . We find that the hyperon onset density exhibits strong sensitivity to $m_{0}$ : for $m_{0} = 500$ MeV, hyperons first appear at $1.9 n_{0}$ while for $m_{0} ≳ 750$ MeV, hyperons emerge only above $5 n_{0}$ . This delayed onset arises from the weakened density dependence of baryon masses at larger $m_{0}$ values. When the hyperon onset density exceeds the expected quark-hadron transition range ( $2$ -- $5 n_{0}$ ), matter undergoes deconfinement before hyperons populate, avoiding the EoS softening while maintaining consistency with massive neutron star observations. Our results demonstrate that chiral dynamics provides a natural resolution to the hyperon puzzle without requiring ad hoc repulsive hyperon interactions.
nucl-thastro-ph.HEPRD(2026)·7 citations
04
Dynamical Origin of Spectroscopic Quenching in Knockout Reactions
Jin Lei
Nucleon-removal reactions are a primary tool for extracting single-particle structure of rare isotopes, yet the ratio $R_{s} = σ_{e x p} / σ_{th}$ of measured to theoretical cross sections drops systematically below unity for deeply bound nucleons. I derive the exact effective three-body Hamiltonian for composite-projectile reactions using a sequential double Feshbach projection and show that the standard additive model misses two induced interactions: a non-additive term from virtual target excitations and a polarization potential from excluded projectile configurations. Their omission overestimates the stripping cross section, producing apparent quenching distinct from genuine nuclear-structure correlations. This mechanism offers a dynamical origin for the strong separation-energy dependence of the quenching ratio, a feature unique to knockout analyses. Existing four-body CDCC calculations for $^{6}$ Li validate the framework: the proper Feshbach reference reproduces elastic scattering data, while a phenomenological optical potential double counts the breakup absorption and fails.
nucl-th2 citations
05
Phase diagrams of BCS-BEC crossover in asymmetric nuclear matter
K. D. Duan · X. L. Shang
The phase structure of the BCS-BEC crossover for neutron-proton superfluid in asymmetric nuclear matter is systematically investigated, with particular focus on the roles of the angle-dependent gap (ADG) and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states. Phase diagrams in the T-alpha, alpha-rho, and T-rho planes are constructed using both angle-averaged and angle-dependent gap treatments, enabling a unified analysis of the interplay between the FFLO pairing, ADG, and normal-superfluid phase separation (PS). The results confirm that the crossover is primarily density-driven. In the weak-coupling BCS regime, isospin asymmetry suppresses the stability of the homogeneous superfluid phase and drives the system toward PS, while the FFLO and ADG mechanisms partially alleviate this suppression. Although the ADG itself does not extend the asymmetry window for superfluidity, in combination with the FFLO state it enlarges the asymmetry range over which superfluidity survives and significantly reduces PS. At high density, these combined effects can nearly eliminate PS. However, as density decreases, ADG-induced suppression of PS is progressively weakened, due to both the reduced destructive effect of isospin asymmetry and the decreasing D-wave fraction in the 3SD1 channel. In general, the system evolves smoothly from a D-wave-dominated superfluid at high density to an S-wave superfluid at low density, with a corresponding weakening of ADG effects. Furthermore, the ADG lifts the orientational degeneracy of the FFLO state, resulting in two distinct FFLO-ADG phases separated by a first-order transition. In contrast, in the BEC regime, the FFLO and ADG states vanish, while the PS persists, leading to an inhomogeneous mixed phase at low temperatures and large asymmetries, where the superfluid component forms a BEC of deuterons.
nucl-th0 citations
06
Subleading D-like Three-Nucleon Interactions
Henri Paul Huesmann🇩🇪 · Hermann Krebs🇩🇪 · Evgeny Epelbaum🇩🇪
We consider subleading contributions to the three-nucleon force from tree-level diagrams involving a single-pion exchange and a contact interaction between two nucleons, which appear at fifth order in the chiral expansion. We show that the corresponding D-like three-nucleon potential depends on 16 low-energy constants, which need to be determined from few-body data. Assuming that their numerical values are governed by the intermediate {\Delta}(1232) excitation mechanism, the considered three-nucleon force can be approximated using 4 low-energy constants that parametrize the short-range nucleon-nucleon to nucleon-{\Delta} transition amplitude.
nucl-thNPA(2026)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

Low-energy 3He(α,γ)7Be reaction within the Skyrme potential framework

Dark matter effects on the properties of hybrid neutron stars

Chiral symmetry restoration and hyperon suppression in neutron stars

Dynamical Origin of Spectroscopic Quenching in Knockout Reactions

Phase diagrams of BCS-BEC crossover in asymmetric nuclear matter

Subleading D-like Three-Nucleon Interactions

Affiliations

Low-energy $^{3}$ He( $α, γ$ ) $^{7}$ Be reaction within the Skyrme potential framework