Highlights
  • Study of the $ {{\boldsymbol J}/\boldsymbol\psi\bf\to \boldsymbol\Lambda\bar{\boldsymbol\Sigma}^{\bf 0}\boldsymbol\eta}$ reaction
    We study the isospin-violating $J/\psi \to \Lambda\bar \Sigma^0 \eta $ reaction, recently measured by the BESIII collaboration, by considering the dominant terms involving $\bar \Sigma^0$ and pairs of pseudoscalar-baryon particles that together form an SU(3) singlet and can therefore couple to the $J/\psi$. We then allow these pairs to undergo final-state interaction to produce the final $\eta \Lambda$. We find that the relevant original channels are $\bar K N$ and $K \Xi$, and that the incomplete cancellation of terms involving charged and neutral particles, owing to their different masses, is responsible for the reaction. With this mechanism, we find good agreement with the three experimental mass distributions.
  • Extending the sensitivity of heavy sterile neutrino searches with solar neutrino experiments
    A sensitivity study of the search for heavy sterile neutrinos ($ \nu_H $) in the MeV mass range using solar neutrino experiments is presented. $ \nu_H $, with masses ranging from a few MeV up to approximately 15 MeV, can be produced in the Sun through 8B decay and subsequently decays into $ \nu_e e^+ e^- $. Its flux and lifetime strongly depend on the mixing parameter $ |U_{eH}|^2 $ and mass $ m_{\nu_H} $. The $ \nu_H $ signal can be detected via its decay products, either the $ e^+e^- $ pair or $ \nu_e $, depending on whether $ \nu_H $ decays inside or outside the detector. Expected signal yields for both detection methods (detecting $ e^+e^- $ or $ \nu_e $ signal) are presented across the full $ |U_{eH}|^2 $ and $ m_{\nu_H} $ parameter spaces. These two methods are found to be complementary in different regions of the $ |U_{eH}|^2 $ and $ m_{\nu_H} $ phase spaces. By combining both approaches, we anticipate observing at least a handful of signal events across most of the parameter space of $ 10^{-6} \lt |U_{eH}|^2 \lt 1 $ and 2 MeV $ \lt m_{\nu_H} \lt $ 15 MeV, assuming a 500-ton solar neutrino experiment operating for one year. Key variables, such as the energy spectra of $ \nu_e $ or $ e^+e^- $ and $ \nu_e $ solar angle, are also discussed to help distinguish the signal from major backgrounds, such as solar neutrino events.
  • Isospin diffusion coefficient for nuclear matter
    A systematic evaluation of the isospin diffusion coefficients of symmetric and β-stable nuclear matter in the low-temperature limit is presented within the Abrikosov–Khalatnikov framework. Key microscopic inputs, including the susceptibility, effective mass, and in-medium differential cross sections, are obtained self-consistently within the Brueckner–Hartree–Fock approach using the realistic Av18 potential, with and without a microscopic three-body force. The inclusion of three-body forces suppresses the effective in-medium cross sections and consequently enhances the diffusion coefficient. Compared with the exact Abrikosov–Khalatnikov results, the neutron–proton total cross-section approximation, which retains only the neutron–proton contribution, provides a comparatively robust description, highlighting the dominant role of the neutron–proton channel. Furthermore, the dependence of the diffusion coefficient on the isospin asymmetry β deviates significantly from the quadratic form $ (1-\beta^2) $ and exhibits a symmetric double-peaked structure. This behavior arises primarily from the β dependence of mixing effects associated with the effective mass, in-medium scattering, and Fermi-momentum splitting, in addition to the contribution from the susceptibility. These results provide useful microscopic input for transport simulations and constraints on the nuclear symmetry energy.
Recent
More >
  • Quasinormal frequencies and greybody factors for axial perturbations of dilaton–Euler–Heisenberg de Sitter black holes
    2027, 51(1): 013107-013107-15. doi: 10.1088/1674-1137/ae9e9c
    Show Abstract
    We investigate the quasinormal modes (QNMs) and greybody factors of dilaton–Euler–Heisenberg (dEH) de Sitter (dS) black holes in string-inspired Euler–Heisenberg gravity. Since the axial gravitational and electromagnetic perturbations decouple, we analyze them independently. By applying the asymptotic iteration method (AIM) together with a sixth-order WKB approximation, we compute the quasinormal frequencies and find excellent agreement between the two methods. We also find that the QNM spectra depend sensitively on the magnetic charge $Q_{\text{m}}$, cosmological constant Λ, and nonlinear coupling $\epsilon$, with a notable topological anomaly appearing in the electromagnetic frequency trajectories. Additionally, larger values of $Q_{\text{m}}$ or the multipole number l generally suppress wave transmission, while the electromagnetic sector with $\epsilon=1$ exhibits an anomalous response.
  • Isospin diffusion coefficient for nuclear matter
    2026, 50(11): 114104-114104-14. doi: 10.1088/1674-1137/ae927a
    Show Abstract
    A systematic evaluation of the isospin diffusion coefficients of symmetric and β-stable nuclear matter in the low-temperature limit is presented within the Abrikosov–Khalatnikov framework. Key microscopic inputs, including the susceptibility, effective mass, and in-medium differential cross sections, are obtained self-consistently within the Brueckner–Hartree–Fock approach using the realistic Av18 potential, with and without a microscopic three-body force. The inclusion of three-body forces suppresses the effective in-medium cross sections and consequently enhances the diffusion coefficient. Compared with the exact Abrikosov–Khalatnikov results, the neutron–proton total cross-section approximation, which retains only the neutron–proton contribution, provides a comparatively robust description, highlighting the dominant role of the neutron–proton channel. Furthermore, the dependence of the diffusion coefficient on the isospin asymmetry β deviates significantly from the quadratic form $ (1-\beta^2) $ and exhibits a symmetric double-peaked structure. This behavior arises primarily from the β dependence of mixing effects associated with the effective mass, in-medium scattering, and Fermi-momentum splitting, in addition to the contribution from the susceptibility. These results provide useful microscopic input for transport simulations and constraints on the nuclear symmetry energy.
  • Correlation between nuclear bubble structure and EMC effect
    2026, 50(11): 111001-111001-8. doi: 10.1088/1674-1137/ae904f
    Show Abstract
    The correlation between the nuclear bubble structure and the EMC effect is investigated within the framework of T. D. Lee's soliton bag model and the double Q2-rescaling model. For 27Al, we artificially reduce its central density via a three-parameter Fermi distribution of nucleon density while conserving the mass number. It is found that as the central density decreases, nucleons are redistributed from the interior to the surface, leading to a systematic reduction in the average nucleon swelling factor, rescaling parameters and the EMC slope. However, this single-parameter modification fails to simultaneously reproduce both the magnitude and the slope of the experimental EMC ratio within the same parameter set, suggesting that additional nuclear medium effects must be considered. For the density distributions of the candidate bubble nucleus 48Si, we calculate them by the Skyrme-Hartree-Fock-Bogoliubov (SHFB) theory with the SLy4, SKM* and LNS interactions, while the density profiles given by the PKA1 interaction are taken from the relativistic Hartree-Fock-Bogoliubov (RHFB) calculation (Phys. Lett. B 788, 192 (2019)). Among the PKA1, SLy4 and SKM* interactions, a stronger bubble structure correlates with a larger nucleon swelling factor and a stronger EMC effect. The LNS interaction, however, presents an exception: despite having a weaker bubble, it yields the largest EMC effect, owing to its systematically higher overall nuclear density. This demonstrates that the EMC effect in bubble nuclei depends on both the bubble strength and the global density scale set by the effective interaction.
Current Issued
Archive