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2026 No.11
2026 No.12
2026, 50(11): 114102. doi: 10.1088/1674-1137/ae836e
Abstract:
A theoretical study of the 7Be(p, γ)8B reaction in the "astrophysical" energy range with the use of ab initio methods is presented. The used approaches are No-Core Shell Model and Cluster Channels Orthogonal Functions Method. The scheme also contains elements of R-matrix theory and procedures for extrapolating various data obtained in ab initio computations. The developed approach as a whole allows one not only to calculate the astrophysical S-factor and all nuclear characteristics that determine its value, but also to evaluate the reliability of the obtained results and to identify the dominant reaction mechanisms against a background of insignificant ones. The high accuracy of the obtained results and has been demonstrated.
A theoretical study of the 7Be(p, γ)8B reaction in the "astrophysical" energy range with the use of ab initio methods is presented. The used approaches are No-Core Shell Model and Cluster Channels Orthogonal Functions Method. The scheme also contains elements of R-matrix theory and procedures for extrapolating various data obtained in ab initio computations. The developed approach as a whole allows one not only to calculate the astrophysical S-factor and all nuclear characteristics that determine its value, but also to evaluate the reliability of the obtained results and to identify the dominant reaction mechanisms against a background of insignificant ones. The high accuracy of the obtained results and has been demonstrated.
2026, 50(11): 114101. doi: 10.1088/1674-1137/ae9050
Abstract:
Heavy-ion charge-exchange (CE) reactions provide a sensitive probe of isospin dynamics in nuclear collisions. We investigate the reaction $^{12}\mathrm{C}(^{12}\mathrm{C},\,^{12}{\rm N}\,{\pi}^{+})\,^{12}\mathrm{Be}$ at 400−600 A MeV using the ultra-relativistic quantum molecular dynamics model coupled with a phase-space coalescence approach. This reaction constitutes a nontrivial CE channel accompanied by single ${\pi}^+$ production in heavy-ion collisions, thereby extending previous studies from lepton-induced to hadronic systems. The $^{12}{\rm N}$ fragment is formed via nucleon and meson exchange, while ${\pi}^+$ production is primarily governed by ∆ resonance excitation and decay; this dual mechanism enables the simultaneous investigation of CE processes and ∆-induced pion production within the same reaction system. We calculate the reaction cross section and analyze the four-momentum distributions of $^{12}{\rm N}$ and ${\pi}^+$. Characteristic phase-space features reflect these distinct production mechanisms and offer guidance for future experimental design. Furthermore, this reaction could serve as a pathway for rare-isotope production.
Heavy-ion charge-exchange (CE) reactions provide a sensitive probe of isospin dynamics in nuclear collisions. We investigate the reaction $^{12}\mathrm{C}(^{12}\mathrm{C},\,^{12}{\rm N}\,{\pi}^{+})\,^{12}\mathrm{Be}$ at 400−600 A MeV using the ultra-relativistic quantum molecular dynamics model coupled with a phase-space coalescence approach. This reaction constitutes a nontrivial CE channel accompanied by single ${\pi}^+$ production in heavy-ion collisions, thereby extending previous studies from lepton-induced to hadronic systems. The $^{12}{\rm N}$ fragment is formed via nucleon and meson exchange, while ${\pi}^+$ production is primarily governed by ∆ resonance excitation and decay; this dual mechanism enables the simultaneous investigation of CE processes and ∆-induced pion production within the same reaction system. We calculate the reaction cross section and analyze the four-momentum distributions of $^{12}{\rm N}$ and ${\pi}^+$. Characteristic phase-space features reflect these distinct production mechanisms and offer guidance for future experimental design. Furthermore, this reaction could serve as a pathway for rare-isotope production.
2026, 50(11): 114103. doi: 10.1088/1674-1137/ae904e
Abstract:
We present a systematic investigation of α-decay half-lives for nuclei with $ 52 \leq Z \leq 122 $ within a microscopic double-folding framework. The α–nucleus potentials are constructed from the Michigan three-range Yukawa (M3Y) nucleon–nucleon interaction and its density-dependent variants (DDM3Y, CDM3Y, and BDM3Y), explicitly incorporating both direct and exchange terms. Special emphasis is placed on the role of finite-range exchange effects, which provide a more realistic description than the conventional zero-range approximation and lead to noticeable modifications in the Coulomb barrier region. Barrier penetrabilities are calculated using the WKB approximation with the Bohr–Sommerfeld quantization condition. The results demonstrate that nuclear deformation generally enhances the tunneling probability, resulting in shorter α-decay half-lives. Furthermore, the calculations indicate that increasing the nuclear incompressibility parameter K within the CDM3Y family tends to shorten the predicted half-lives by slightly enhancing the barrier penetrability. The calculated isotopic trends reflect the characteristic behavior near the neutron shell closures at $ N=82 $, 126, and 184, highlighting the interplay between nuclear structure effects and decay dynamics. Overall, the results provide a systematic assessment of the sensitivity of α-decay half-lives to finite-range exchange, density dependence, deformation, and nuclear incompressibility within this microscopic double-folding approach.
We present a systematic investigation of α-decay half-lives for nuclei with $ 52 \leq Z \leq 122 $ within a microscopic double-folding framework. The α–nucleus potentials are constructed from the Michigan three-range Yukawa (M3Y) nucleon–nucleon interaction and its density-dependent variants (DDM3Y, CDM3Y, and BDM3Y), explicitly incorporating both direct and exchange terms. Special emphasis is placed on the role of finite-range exchange effects, which provide a more realistic description than the conventional zero-range approximation and lead to noticeable modifications in the Coulomb barrier region. Barrier penetrabilities are calculated using the WKB approximation with the Bohr–Sommerfeld quantization condition. The results demonstrate that nuclear deformation generally enhances the tunneling probability, resulting in shorter α-decay half-lives. Furthermore, the calculations indicate that increasing the nuclear incompressibility parameter K within the CDM3Y family tends to shorten the predicted half-lives by slightly enhancing the barrier penetrability. The calculated isotopic trends reflect the characteristic behavior near the neutron shell closures at $ N=82 $, 126, and 184, highlighting the interplay between nuclear structure effects and decay dynamics. Overall, the results provide a systematic assessment of the sensitivity of α-decay half-lives to finite-range exchange, density dependence, deformation, and nuclear incompressibility within this microscopic double-folding approach.
2026, 50(11): 114104. doi: 10.1088/1674-1137/ae927a
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.
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.
2026, 50(11): 114107. doi: 10.1088/1674-1137/ae9917
Abstract:
The charge radii of calcium isotopes are investigated within the framework of relativistic configuration-interaction density functional (ReCD) theory. The ReCD theory microscopically incorporates beyond-mean-field correlations through rotational symmetry restoration and configuration mixing among quasiparticle excited states, treating both even-even and odd-A isotopes on the same footing. It is found that beyond-mean-field correlations significantly soften the potential energy surfaces of calcium isotopes and shift the energy minima from nearly spherical mean-field solutions to deformed shapes. The quadrupole deformation parameters predicted by the ReCD theory show much better agreement with the available experimental data than the mean-field results, supporting the reliability of the calculated potential energy surfaces and highlighting the crucial role of beyond-mean-field correlations. Due to the sensitive dependence of charge radii on nuclear deformation, the charge radii obtained within the ReCD framework are generally larger than the mean-field predictions. The nearly identical charge radii of $ ^{40}\mathrm{Ca} $ and $ ^{48}\mathrm{Ca} $, as well as the unexpectedly large charge radius of $ ^{52}\mathrm{Ca} $, are well reproduced. Compared with the mean-field calculations, the description of the odd-even staggering is improved, particularly for the enhanced charge radii of $ ^{42}\mathrm{Ca} $ and $ ^{44}\mathrm{Ca} $. It is also noteworthy that secondary local minima appear in the ReCD-based potential energy surfaces of the odd-A calcium isotopes $ ^{41,43,47}\mathrm{Ca} $. The present results suggest that shape mixing between different local minima, which is not fully included in the current calculation, may further improve the description of the pronounced odd-even staggering observed in calcium isotopes.
The charge radii of calcium isotopes are investigated within the framework of relativistic configuration-interaction density functional (ReCD) theory. The ReCD theory microscopically incorporates beyond-mean-field correlations through rotational symmetry restoration and configuration mixing among quasiparticle excited states, treating both even-even and odd-A isotopes on the same footing. It is found that beyond-mean-field correlations significantly soften the potential energy surfaces of calcium isotopes and shift the energy minima from nearly spherical mean-field solutions to deformed shapes. The quadrupole deformation parameters predicted by the ReCD theory show much better agreement with the available experimental data than the mean-field results, supporting the reliability of the calculated potential energy surfaces and highlighting the crucial role of beyond-mean-field correlations. Due to the sensitive dependence of charge radii on nuclear deformation, the charge radii obtained within the ReCD framework are generally larger than the mean-field predictions. The nearly identical charge radii of $ ^{40}\mathrm{Ca} $ and $ ^{48}\mathrm{Ca} $, as well as the unexpectedly large charge radius of $ ^{52}\mathrm{Ca} $, are well reproduced. Compared with the mean-field calculations, the description of the odd-even staggering is improved, particularly for the enhanced charge radii of $ ^{42}\mathrm{Ca} $ and $ ^{44}\mathrm{Ca} $. It is also noteworthy that secondary local minima appear in the ReCD-based potential energy surfaces of the odd-A calcium isotopes $ ^{41,43,47}\mathrm{Ca} $. The present results suggest that shape mixing between different local minima, which is not fully included in the current calculation, may further improve the description of the pronounced odd-even staggering observed in calcium isotopes.
2026, 50(11): 115104. doi: 10.1088/1674-1137/ae9926
Abstract:
Based on the fractional entropy from fractional quantum mechanics, fractional holographic dark energy (FHDE) has been proposed with the Hubble horizon as the IR cutoff (FHDEH). We extend this framework by adopting the future event horizon and the particle horizon as the IR cutoff and proposing the FHDEF and FHDEP models. Using the SN+OHD+DESI DR2 dataset to constrain these models, we find that all three models provide a marginally lower $\chi^{2}_{\min}$ compared to ΛCDM but without significant preference according to AIC and BIC. When CMB distance priors are included, the FHDEH and FHDEP models are strongly ruled out. We further analyze the cosmological evolution for these models, and find that only the FHDEF model predicts nearly identical evolutions of $ \Omega_{m} $ and $ \Omega_{\rm de} $ to those of the ΛCDM model across cosmic history, but its deceleration parameter q deviates from the ΛCDM model in the future, indicating richer late time dynamics beyond the standard ΛCDM cosmology.
Based on the fractional entropy from fractional quantum mechanics, fractional holographic dark energy (FHDE) has been proposed with the Hubble horizon as the IR cutoff (FHDEH). We extend this framework by adopting the future event horizon and the particle horizon as the IR cutoff and proposing the FHDEF and FHDEP models. Using the SN+OHD+DESI DR2 dataset to constrain these models, we find that all three models provide a marginally lower $\chi^{2}_{\min}$ compared to ΛCDM but without significant preference according to AIC and BIC. When CMB distance priors are included, the FHDEH and FHDEP models are strongly ruled out. We further analyze the cosmological evolution for these models, and find that only the FHDEF model predicts nearly identical evolutions of $ \Omega_{m} $ and $ \Omega_{\rm de} $ to those of the ΛCDM model across cosmic history, but its deceleration parameter q deviates from the ΛCDM model in the future, indicating richer late time dynamics beyond the standard ΛCDM cosmology.
2026, 50(11): 115103. doi: 10.1088/1674-1137/ae97ea
Abstract:
In this paper, we study a self-dual black hole (BH) in loop quantum gravity (LQG) by analyzing both timelike and null geodesics. Using observational data from Mercury’s perihelion shift and the orbit of the S2 star around Sagittarius A* (Sgr A*), we derive constraints on the polymeric function P. We also investigate photon trajectories near the self-dual BH under various scenarios to assess their observational relevance. Finally, we examine the properties of accretion disks around the self-dual BH in LQG, including their direct and secondary images. We further study the redshift and observed energy-flux distribution across the accretion disk, as measured by distant observers at different inclination angles. Our findings provide new insights into the physical nature and accretion properties of self-dual BHs in LQG and their possible observational consequences.
In this paper, we study a self-dual black hole (BH) in loop quantum gravity (LQG) by analyzing both timelike and null geodesics. Using observational data from Mercury’s perihelion shift and the orbit of the S2 star around Sagittarius A* (Sgr A*), we derive constraints on the polymeric function P. We also investigate photon trajectories near the self-dual BH under various scenarios to assess their observational relevance. Finally, we examine the properties of accretion disks around the self-dual BH in LQG, including their direct and secondary images. We further study the redshift and observed energy-flux distribution across the accretion disk, as measured by distant observers at different inclination angles. Our findings provide new insights into the physical nature and accretion properties of self-dual BHs in LQG and their possible observational consequences.
2026, 50(11): 115106. doi: 10.1088/1674-1137/ae8cf1
Abstract:
We investigate the spectral dynamics of a rotating black hole embedded in a Dehnen $(1,4,\gamma)$ dark matter halo, in which quasibound states and superradiant scattering jointly characterize the physical response of the system. Starting from an exact Schwarzschild–Dehnen solution, we construct its rotating counterpart via the Newman–Janis algorithm, thereby obtaining a consistent axisymmetric geometry that incorporates the influence of a structured halo. Through its inner slope parameter γ, the Dehnen profile introduces a controlled deformation of both the near-horizon and asymptotic regions of the spacetime. Using the analytical asymptotic matching method, we derive the quasibound-state spectrum and show that the real part of the frequency retains a hydrogen-like structure but is systematically shifted by the leading-order halo correction proportional to $\rho_0 r_0^3/(3-\gamma)$. In particular, denser, more extended, and cuspier halos strengthen the binding of the quasibound states, lower the critical mass required for the onset of instability, and typically suppress the growth rate of the black hole bomb. In the scattering sector, we obtain an analytic expression for the superradiant amplification factor and find that the same halo properties that strengthen the binding effects also tend to narrow the superradiant window. These results demonstrate that quasibound states and superradiant scattering are complementary manifestations of a unified spectral structure, with the Dehnen halo acting as an environmental tuner that directly imprints its properties onto both the resonance spectrum and the energy-extraction channels of the rotating black hole.
We investigate the spectral dynamics of a rotating black hole embedded in a Dehnen $(1,4,\gamma)$ dark matter halo, in which quasibound states and superradiant scattering jointly characterize the physical response of the system. Starting from an exact Schwarzschild–Dehnen solution, we construct its rotating counterpart via the Newman–Janis algorithm, thereby obtaining a consistent axisymmetric geometry that incorporates the influence of a structured halo. Through its inner slope parameter γ, the Dehnen profile introduces a controlled deformation of both the near-horizon and asymptotic regions of the spacetime. Using the analytical asymptotic matching method, we derive the quasibound-state spectrum and show that the real part of the frequency retains a hydrogen-like structure but is systematically shifted by the leading-order halo correction proportional to $\rho_0 r_0^3/(3-\gamma)$. In particular, denser, more extended, and cuspier halos strengthen the binding of the quasibound states, lower the critical mass required for the onset of instability, and typically suppress the growth rate of the black hole bomb. In the scattering sector, we obtain an analytic expression for the superradiant amplification factor and find that the same halo properties that strengthen the binding effects also tend to narrow the superradiant window. These results demonstrate that quasibound states and superradiant scattering are complementary manifestations of a unified spectral structure, with the Dehnen halo acting as an environmental tuner that directly imprints its properties onto both the resonance spectrum and the energy-extraction channels of the rotating black hole.
2026, 50(11): 115102. doi: 10.1088/1674-1137/ae8db3
Abstract:
Timelike orbits constitute a crucial probe for exploring the intrinsic properties of curved spacetimes, and the accompanying gravitational radiation signals provide a direct window into strong field gravity. In this paper, we develop a versatile computational framework based on Mathematica and the OpenMP parallel architecture to simulate the rational orbits of timelike particles and their gravitational radiation in static spherically symmetric spacetimes. Specifically, with only the user defined covariant metric as input, this numerical tool can efficiently calculate rational orbits for various configurations, as well as the corresponding gravitational wave polarization states and characteristic strains. The package presented here provides an efficient and comprehensive tool for investigating the properties of curved spacetimes and their potential observational signatures. To demonstrate the reliability and capability of our code, we apply it to the Schwarzschild spacetime as a test case, illustrating its functionality in several key aspects, including the effective potential, stable orbital regions, rational and irrational orbits, and gravitational wave signals. Furthermore, we show that the gravitational waves emitted by an extreme-mass-ratio inspiral system composed of an intermediate mass black hole and the Galactic Center supermassive black hole could be detected by future space detectors.
Timelike orbits constitute a crucial probe for exploring the intrinsic properties of curved spacetimes, and the accompanying gravitational radiation signals provide a direct window into strong field gravity. In this paper, we develop a versatile computational framework based on Mathematica and the OpenMP parallel architecture to simulate the rational orbits of timelike particles and their gravitational radiation in static spherically symmetric spacetimes. Specifically, with only the user defined covariant metric as input, this numerical tool can efficiently calculate rational orbits for various configurations, as well as the corresponding gravitational wave polarization states and characteristic strains. The package presented here provides an efficient and comprehensive tool for investigating the properties of curved spacetimes and their potential observational signatures. To demonstrate the reliability and capability of our code, we apply it to the Schwarzschild spacetime as a test case, illustrating its functionality in several key aspects, including the effective potential, stable orbital regions, rational and irrational orbits, and gravitational wave signals. Furthermore, we show that the gravitational waves emitted by an extreme-mass-ratio inspiral system composed of an intermediate mass black hole and the Galactic Center supermassive black hole could be detected by future space detectors.
2026, 50(11): 115101. doi: 10.1088/1674-1137/ae8cf0
Abstract:
In this paper, we investigate the photon regions, shadow, and observational constraints of a Kerr-Newman-like black hole in Bumblebee gravity within a plasma medium. Using a specific non-homogeneous power-law plasma model to ensure the separability of the Hamilton-Jacobi equation, we derive the null geodesic equations, analyze the photon regions, and construct the black hole shadow. Furthermore, we introduce two sets of shadow observables to systematically analyze the distinct effects of each physical parameter (spin a, charge $ Q_0 $, Lorentz-violating parameter ℓ, and plasma parameter k) on the shadow geometry. Specifically, we find that a and ℓ mainly enhance the distortion of the shadow, whereas $ Q_0 $ and k primarily lead to radial shrinkage. In addition, a brief evaluation of the energy emission rate shows that increasing these parameters generally suppresses the emission peak. Finally, by modeling M87* as a charged, rotating black hole in Bumblebee gravity surrounded by plasma, we constrain the physical parameters using observations from the Event Horizon Telescope (EHT). For a fixed viewing angle of $ 17^\circ $, the angular diameter $ \theta_d = 42 \pm 3 \, \mu\mathrm{as} $ narrows the viable parameter space, while the circularity deviation $ \Delta C \lesssim 0.1 $ and axis ratio $ 1 \lt D_x \lesssim 4/3 $ satisfy the EHT limits. This suggests that the charged, rotating black hole in Bumblebee gravity surrounded by plasma may be a candidate for real astrophysical black holes.
In this paper, we investigate the photon regions, shadow, and observational constraints of a Kerr-Newman-like black hole in Bumblebee gravity within a plasma medium. Using a specific non-homogeneous power-law plasma model to ensure the separability of the Hamilton-Jacobi equation, we derive the null geodesic equations, analyze the photon regions, and construct the black hole shadow. Furthermore, we introduce two sets of shadow observables to systematically analyze the distinct effects of each physical parameter (spin a, charge $ Q_0 $, Lorentz-violating parameter ℓ, and plasma parameter k) on the shadow geometry. Specifically, we find that a and ℓ mainly enhance the distortion of the shadow, whereas $ Q_0 $ and k primarily lead to radial shrinkage. In addition, a brief evaluation of the energy emission rate shows that increasing these parameters generally suppresses the emission peak. Finally, by modeling M87* as a charged, rotating black hole in Bumblebee gravity surrounded by plasma, we constrain the physical parameters using observations from the Event Horizon Telescope (EHT). For a fixed viewing angle of $ 17^\circ $, the angular diameter $ \theta_d = 42 \pm 3 \, \mu\mathrm{as} $ narrows the viable parameter space, while the circularity deviation $ \Delta C \lesssim 0.1 $ and axis ratio $ 1 \lt D_x \lesssim 4/3 $ satisfy the EHT limits. This suggests that the charged, rotating black hole in Bumblebee gravity surrounded by plasma may be a candidate for real astrophysical black holes.
2026, 50(11): 114106. doi: 10.1088/1674-1137/ae92f5
Abstract:
The temperature dependence of neutron star structure significantly alters the equation of state, thereby affecting observable properties such as the moment of inertia and gravitational redshift. Using relativistic mean-field (RMF) theory with hyperonic degrees of freedom under SU(3) flavor and SU(6) spin-flavor symmetries, we investigate thermal effects on the structural properties of protoneutron stars (PNSs) and cold neutron stars (CNSs). Focusing on PSR J1012+5307, we analyze the pronounced structural transformations that occur during the transition from a PNS to a CNS. For a 1.94 $M_{\odot}$ hyperonic star under SU(3) flavor symmetry, decreasing the temperature from $T = 30$ MeV to 0 MeV induces a radius contraction of approximately 50%, accompanied by a decrease in the moment of inertia of nearly 26% and a substantial increase in gravitational redshift of approximately 154%. Furthermore, we examine variations in the moment of inertia and gravitational redshift arising from the mass uncertainties of PSR J1012+5307. Taking SU(3) flavor symmetry at $T=20$ MeV as an example, increasing the mass across the range 1.72−$1.94 \,\, M_{\odot} $ leads to a radius contraction of 2.749 km, an ~8% increase in the moment of inertia, and a substantial ~40% increase in the gravitational redshift. We find that, in the cold regime and at fixed mass, the radius, moment of inertia, and gravitational redshift of hyperonic matter under SU(3) flavor symmetry differ only marginally from those of purely nucleonic matter. This makes it difficult to observationally confirm the presence of hyperons in the core of PSR J1012+5307. Moreover, future observations that can precisely constrain pulsar masses, ideally through long-term monitoring from birth, may help determine more conclusively whether hyperons or other exotic matter reside in individual pulsars.
The temperature dependence of neutron star structure significantly alters the equation of state, thereby affecting observable properties such as the moment of inertia and gravitational redshift. Using relativistic mean-field (RMF) theory with hyperonic degrees of freedom under SU(3) flavor and SU(6) spin-flavor symmetries, we investigate thermal effects on the structural properties of protoneutron stars (PNSs) and cold neutron stars (CNSs). Focusing on PSR J1012+5307, we analyze the pronounced structural transformations that occur during the transition from a PNS to a CNS. For a 1.94 $M_{\odot}$ hyperonic star under SU(3) flavor symmetry, decreasing the temperature from $T = 30$ MeV to 0 MeV induces a radius contraction of approximately 50%, accompanied by a decrease in the moment of inertia of nearly 26% and a substantial increase in gravitational redshift of approximately 154%. Furthermore, we examine variations in the moment of inertia and gravitational redshift arising from the mass uncertainties of PSR J1012+5307. Taking SU(3) flavor symmetry at $T=20$ MeV as an example, increasing the mass across the range 1.72−$1.94 \,\, M_{\odot} $ leads to a radius contraction of 2.749 km, an ~8% increase in the moment of inertia, and a substantial ~40% increase in the gravitational redshift. We find that, in the cold regime and at fixed mass, the radius, moment of inertia, and gravitational redshift of hyperonic matter under SU(3) flavor symmetry differ only marginally from those of purely nucleonic matter. This makes it difficult to observationally confirm the presence of hyperons in the core of PSR J1012+5307. Moreover, future observations that can precisely constrain pulsar masses, ideally through long-term monitoring from birth, may help determine more conclusively whether hyperons or other exotic matter reside in individual pulsars.
2026, 50(11): 113107. doi: 10.1088/1674-1137/ae97e9
Abstract:
We investigate the magnetic dipole moments of doubly-bottom pentaquark states with spin-parities $J^P= {1}/{2}^-$ and $ {3}/{2}^-$, interpreted as hadronic molecules in the $B\Sigma_b$, $B\Sigma_b^{*}$, and $B^{*}\Sigma_b$ configurations. The analysis is conducted within the framework of QCD light-cone sum rules employing photon distribution amplitudes. Our results demonstrate a strong sensitivity of the magnetic dipole moments to the internal spin structure and quark composition of the states. Specifically, the light-quark sector provides the dominant contribution in the $B\Sigma_b$ configuration, whereas the magnetic moment of $B\Sigma_b^{*}$ is largely governed by the heavy bottom quark. For the $B^{*}\Sigma_b$ molecular state, both light and heavy sectors contribute constructively, leading to a significantly enhanced magnetic dipole moment. These findings indicate that magnetic dipole moments serve as a sensitive probe of the internal structure of molecular-type doubly-bottom pentaquarks and provide testable predictions for future experimental studies.
We investigate the magnetic dipole moments of doubly-bottom pentaquark states with spin-parities $J^P= {1}/{2}^-$ and $ {3}/{2}^-$, interpreted as hadronic molecules in the $B\Sigma_b$, $B\Sigma_b^{*}$, and $B^{*}\Sigma_b$ configurations. The analysis is conducted within the framework of QCD light-cone sum rules employing photon distribution amplitudes. Our results demonstrate a strong sensitivity of the magnetic dipole moments to the internal spin structure and quark composition of the states. Specifically, the light-quark sector provides the dominant contribution in the $B\Sigma_b$ configuration, whereas the magnetic moment of $B\Sigma_b^{*}$ is largely governed by the heavy bottom quark. For the $B^{*}\Sigma_b$ molecular state, both light and heavy sectors contribute constructively, leading to a significantly enhanced magnetic dipole moment. These findings indicate that magnetic dipole moments serve as a sensitive probe of the internal structure of molecular-type doubly-bottom pentaquarks and provide testable predictions for future experimental studies.
2026, 50(11): 113104. doi: 10.1088/1674-1137/ae8f26
Abstract:
We refine the hadronization sector of a pp PYTHIA 8 tune for $ e^+e^-\to q\bar q $ production using selected BELLE and BABAR measurements near the $ \Upsilon(4S) $ region. The study is performed with PYTHIA 8.316 and Rivet 4.1.1 and is restricted to the parameters used in this $ e^+e^- $ setup. Starting from the five-parameter hadronization subset of the pp tune, we perform a staged extension guided by the remaining discrepancies with the BELLE and BABAR data. The final comparison uses a fixed common set of 20,803 bins and samples of 1,000,000 generated events per analysis and tune point. On this basis, the selected refined tune yields a bin-weighted score of 73.42, compared with 76.49 for the Skands $ e^+e^- $ reference and 79.22 for Monash 2013 $ e^+e^- $. It remains the best-scoring tune for the BELLE charged-hadron, baryon, and single- and dihadron measurements, whereas Skands still performs better for the BABAR charged-hadron sample and the BELLE meson sample. The bin-weighted ordering is driven primarily by the BELLE 2020 sample. The refined tune provides a small but stable improvement for the selected BELLE and BABAR measurements, although clear differences among the individual datasets remain.
We refine the hadronization sector of a pp PYTHIA 8 tune for $ e^+e^-\to q\bar q $ production using selected BELLE and BABAR measurements near the $ \Upsilon(4S) $ region. The study is performed with PYTHIA 8.316 and Rivet 4.1.1 and is restricted to the parameters used in this $ e^+e^- $ setup. Starting from the five-parameter hadronization subset of the pp tune, we perform a staged extension guided by the remaining discrepancies with the BELLE and BABAR data. The final comparison uses a fixed common set of 20,803 bins and samples of 1,000,000 generated events per analysis and tune point. On this basis, the selected refined tune yields a bin-weighted score of 73.42, compared with 76.49 for the Skands $ e^+e^- $ reference and 79.22 for Monash 2013 $ e^+e^- $. It remains the best-scoring tune for the BELLE charged-hadron, baryon, and single- and dihadron measurements, whereas Skands still performs better for the BABAR charged-hadron sample and the BELLE meson sample. The bin-weighted ordering is driven primarily by the BELLE 2020 sample. The refined tune provides a small but stable improvement for the selected BELLE and BABAR measurements, although clear differences among the individual datasets remain.
2026, 50(11): 113103. doi: 10.1088/1674-1137/ae91ce
Abstract:
In recent years, long-lived particles (LLPs) have attracted increasing attention in searches for physics beyond the Standard Model (SM). In this paper, we investigate the discovery prospects for light, long-lived ALPs predicted by the photophobic ALP scenario through displaced-vertex signals at the CEPC, with a center-of-mass energy of $ \sqrt{s}=91.2 $ GeV and an integrated luminosity of $ {\cal{L}}= $ 100 ab−1. After comparing several possible single-production processes for the photophobic ALP, we focus on the dominant process $ e^+ e^- \to Z \to a \gamma $, in which the ALP a subsequently decays into a pair of charged leptons at a displaced vertex. Dedicated Monte Carlo simulations are performed for the $ \mu^+ \mu^- \gamma $ and $ \tau_h^+ \tau_h^- \not{E}_T \gamma $ signals. For the $ \mu^+\mu^-\gamma $ signal, the CEPC is sensitive to the parameter region $ g_{aWW} \in [1.27\times10^{-3},6.80\times10^{-1}]\; {\rm{TeV}}^{-1} $ for $ m_a \in [1,4]\; {\rm{GeV}} $. For the $ \tau_h^+\tau_h^-\not{E}_T\gamma $ signal, the accessible region is $ g_{aWW} \in [7.00\times10^{-4},9.40\times10^{-3}]\; {\rm{TeV}}^{-1} $ for $ m_a \in [4,9]\; {\rm{GeV}} $. These results demonstrate the substantial potential of the CEPC to explore light, long-lived ALPs through displaced-vertex signals, providing complementary coverage to existing searches at LEP and the LHC, as well as to the projected reach of the HL-LHC.
In recent years, long-lived particles (LLPs) have attracted increasing attention in searches for physics beyond the Standard Model (SM). In this paper, we investigate the discovery prospects for light, long-lived ALPs predicted by the photophobic ALP scenario through displaced-vertex signals at the CEPC, with a center-of-mass energy of $ \sqrt{s}=91.2 $ GeV and an integrated luminosity of $ {\cal{L}}= $ 100 ab−1. After comparing several possible single-production processes for the photophobic ALP, we focus on the dominant process $ e^+ e^- \to Z \to a \gamma $, in which the ALP a subsequently decays into a pair of charged leptons at a displaced vertex. Dedicated Monte Carlo simulations are performed for the $ \mu^+ \mu^- \gamma $ and $ \tau_h^+ \tau_h^- \not{E}_T \gamma $ signals. For the $ \mu^+\mu^-\gamma $ signal, the CEPC is sensitive to the parameter region $ g_{aWW} \in [1.27\times10^{-3},6.80\times10^{-1}]\; {\rm{TeV}}^{-1} $ for $ m_a \in [1,4]\; {\rm{GeV}} $. For the $ \tau_h^+\tau_h^-\not{E}_T\gamma $ signal, the accessible region is $ g_{aWW} \in [7.00\times10^{-4},9.40\times10^{-3}]\; {\rm{TeV}}^{-1} $ for $ m_a \in [4,9]\; {\rm{GeV}} $. These results demonstrate the substantial potential of the CEPC to explore light, long-lived ALPs through displaced-vertex signals, providing complementary coverage to existing searches at LEP and the LHC, as well as to the projected reach of the HL-LHC.
2026, 50(11): 113102. doi: 10.1088/1674-1137/ae8cf3
Abstract:
Confinement and dynamical chiral symmetry breaking are two emergent non-perturbative phenomena of quantum chromodynamics (QCD) that are responsible for the nature of hadron spectra. While it is well known that the chiral condensate $ -\langle\bar{\psi} \psi \rangle $ is an order parameter for the chiral transition, the Polyakov loop is the associated approximate order parameter for the confinement–deconfinement transition in the pure gauge sector with center symmetry. Nevertheless, this quantity cannot be derived from functional methods, and other quantities have therefore been proposed as order parameters for this transition. In the current investigation, we review and compare several proposed parameters that have been used to describe the confinement/deconfinement transition in QCD and related quantum field theories in the framework of Schwinger–Dyson equations.
Confinement and dynamical chiral symmetry breaking are two emergent non-perturbative phenomena of quantum chromodynamics (QCD) that are responsible for the nature of hadron spectra. While it is well known that the chiral condensate $ -\langle\bar{\psi} \psi \rangle $ is an order parameter for the chiral transition, the Polyakov loop is the associated approximate order parameter for the confinement–deconfinement transition in the pure gauge sector with center symmetry. Nevertheless, this quantity cannot be derived from functional methods, and other quantities have therefore been proposed as order parameters for this transition. In the current investigation, we review and compare several proposed parameters that have been used to describe the confinement/deconfinement transition in QCD and related quantum field theories in the framework of Schwinger–Dyson equations.
2026, 50(12): 063003. doi: 10.1088/1674-1137/ae457d
Abstract:
Geoneutrinos—antineutrinos emitted during the decay of long-lived radioactive elements inside the Earth—serve as a unique tool for studying our planet's composition and heat budget. The Jiangmen Underground Neutrino Observatory (JUNO) experiment in China, which has recently completed construction, is expected to collect a sample comparable in size to the entire existing world geoneutrino dataset in less than a year. This paper presents an updated estimation of JUNO's sensitivity to geoneutrinos using the best knowledge available to date about the experimental site, the surrounding nuclear reactors, the detector response uncertainties, and the knowledge of the reactor antineutrino flux. To facilitate comparison with present and future geological models, our results cover a wide range of predicted signal strengths. Despite the significant background from reactor antineutrinos, the primary channel JUNO will use to determine the neutrino mass ordering, the experiment will measure the total geoneutrino flux with a precision comparable to that of existing experiments within its first few years, ultimately achieving a world-leading precision of about 8% over ten years. JUNO's large statistics will also allow separation of the Uranium-238 and Thorium-232 contributions with unprecedented precision, providing crucial constraints on models of Earth’s formation and composition. Observation of the mantle signal above the lithospheric flux will be possible but challenging. For models with the highest predicted mantle concentrations of heat-producing elements, a ~$3\sigma$ detection over six years requires knowledge of the lithospheric flux to within 15%. Together with complementary measurements from other locations, JUNO’s geoneutrino results will offer cutting-edge, high-precision insights into the Earth’s interior, of fundamental importance to both the geoscience and neutrino physics communities.
Geoneutrinos—antineutrinos emitted during the decay of long-lived radioactive elements inside the Earth—serve as a unique tool for studying our planet's composition and heat budget. The Jiangmen Underground Neutrino Observatory (JUNO) experiment in China, which has recently completed construction, is expected to collect a sample comparable in size to the entire existing world geoneutrino dataset in less than a year. This paper presents an updated estimation of JUNO's sensitivity to geoneutrinos using the best knowledge available to date about the experimental site, the surrounding nuclear reactors, the detector response uncertainties, and the knowledge of the reactor antineutrino flux. To facilitate comparison with present and future geological models, our results cover a wide range of predicted signal strengths. Despite the significant background from reactor antineutrinos, the primary channel JUNO will use to determine the neutrino mass ordering, the experiment will measure the total geoneutrino flux with a precision comparable to that of existing experiments within its first few years, ultimately achieving a world-leading precision of about 8% over ten years. JUNO's large statistics will also allow separation of the Uranium-238 and Thorium-232 contributions with unprecedented precision, providing crucial constraints on models of Earth’s formation and composition. Observation of the mantle signal above the lithospheric flux will be possible but challenging. For models with the highest predicted mantle concentrations of heat-producing elements, a ~$3\sigma$ detection over six years requires knowledge of the lithospheric flux to within 15%. Together with complementary measurements from other locations, JUNO’s geoneutrino results will offer cutting-edge, high-precision insights into the Earth’s interior, of fundamental importance to both the geoscience and neutrino physics communities.
2026, 50(11): 111001. doi: 10.1088/1674-1137/ae904f
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.
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.
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Cover Story
- Cover Story (Issue 9, 2026): Charge Separation Measurements in Au+Au collisions at \sqrt{S_{NN}} = 7.7-200 GeV in Search of the Chiral Magnetic Effect
- Cover Story (Issue 5, 2026): Determination of Fragmentation Functions from Charge Asymmetries in Hadron Production
- Cover Story (Issue 4, 2026): Initial performance results of the JUNO detector
- Cover Story (Issue 3, 2026): Comprehensive investigation on baryon number violating nucleon decays involving an axion-like particle
- Cover Story (Issue 2, 2026) |The images of Brans-Dicke-Kerr type naked singularities
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