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2025 No.7
2025, 49(7): 074111. doi: 10.1088/1674-1137/adcf8e
Abstract:
This paper discusses the structure and stability of quark stars (QSs) made of interacting quark matter. The discussion accounts for color superconductivity and perturbative QCD corrections. By combining this EoS with the Tolman-Oppenheimer-Volkoff (TOV) equations, we explore the mass-radius ($ M-R $ ) relations of QSs. The analysis is conducted within the framework of $ R^2 $ gravity, where the model of gravity is described by $ f(R) = R + a R^2 $ . Our primary goal is to investigate how variations in the $ R^2 $ gravity parameter a affect the mass-radius and mass-central density ($ M-\rho_c $ ) relationships of QSs. Furthermore, we study the dynamical stability of these stars by analyzing the impact of the anisotropy parameter β and interaction parameter λ derived from the EoS on their stability. Our results demonstrate that the presence of pressure anisotropy is crucial for increasing the maximum mass of QSs. The results hint at the existence of super-massive pulsars. These findings are in agreement with recent astronomical observations, which suggest the possibility of neutron stars with masses exceeding $ 2M_{\odot} $ .
This paper discusses the structure and stability of quark stars (QSs) made of interacting quark matter. The discussion accounts for color superconductivity and perturbative QCD corrections. By combining this EoS with the Tolman-Oppenheimer-Volkoff (TOV) equations, we explore the mass-radius (
2025, 49(7): 074007. doi: 10.1088/1674-1137/add09a
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The cross sections of the 148Sm(n,α)145Nd reaction were measured for the first time at neutron energies ranging from 4.8 to 5.3 MeV. The experiment was carried out on the Van de Graaff accelerator EG–5 at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research. Fast neutrons were produced via the 2H(d,n)3He reaction with a deuterium gas target. A twin gridded ionization chamber was used as the charged particle detector, with back–to–back 148Sm samples mounted on tantalum backings at the common cathode. The absolute neutron flux was measured using the 238U3O8 sample. The obtained cross section data were compared with those from existing nuclear data libraries and theoretical calculations using the TALYS–1.96 code. The present results for the 148Sm(n,α)145Nd reaction are expected to resolve discrepancies among various nuclear evaluation data.
The cross sections of the 148Sm(n,α)145Nd reaction were measured for the first time at neutron energies ranging from 4.8 to 5.3 MeV. The experiment was carried out on the Van de Graaff accelerator EG–5 at the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research. Fast neutrons were produced via the 2H(d,n)3He reaction with a deuterium gas target. A twin gridded ionization chamber was used as the charged particle detector, with back–to–back 148Sm samples mounted on tantalum backings at the common cathode. The absolute neutron flux was measured using the 238U3O8 sample. The obtained cross section data were compared with those from existing nuclear data libraries and theoretical calculations using the TALYS–1.96 code. The present results for the 148Sm(n,α)145Nd reaction are expected to resolve discrepancies among various nuclear evaluation data.
2025, 49(7): 074112. doi: 10.1088/1674-1137/adcf8f
Abstract:
The effects of the tensor force on the$2\nu\beta\beta$ and $0\nu\beta\beta$ decay nuclear matrix elements (NMEs) of $^{76}{\rm{Ge}}$ ,$^{82}{\rm{Se}}$ , $^{130}{\rm{Te}}$ , and $^{136}{\rm{Xe}}$ are studied using the Hartree-Fock-Bogoliubov (HFB) plus proton-neutron quasi-particle random phase approximation (pnQRPA) model based on the Skyrme energy density functional. We include the full spectra of intermediate states with $J^{\pi}=0^{\pm}\sim 10^{\pm}$ up to the energy cutoff E = 60 MeV, which is sufficient for convergence of NME calculations. The isovector (IV) pairing and tensor interactions are considered in both HFB and QRPA calculations, while the isoscalar (IS) pairing interaction is included only in QRPA calculations. We found that the tensor force shifts Gamow-Teller (GT) transition strengths substantially to low-energy regions and enhances the $2\nu\beta\beta$ decay NME. The inclusion of tensor force enhances the $0\nu\beta\beta$ NME by approximately 13% for $^{76}{\rm{Ge}}$ and $^{82}{\rm{Se}}$ and 30% for $^{130}{\rm{Te}}$ and $^{136}{\rm{Xe}}$ , for a fixed IS pairing strength. We found that the intermediate 2- state makes an important contribution to the $0\nu\beta\beta$ NME, which is slightly enhanced by the inclusion of the tensor force. We also found that the contribution of the $1^+$ state makes important differences through the inclusion of the tensor force, which enhances the contribution largely. However when the IS pairing strength is increased, the contributions from 1+ states are rapidly reduced to be very small, resulting in even negative contributions. Thus, tensor and IS pairing effects cancel each other, making the net effect on the NME relatively small. Due to this cancellation, if the IS pairing strength is optimized separately for cases with and without the tensor interaction to reproduce the experimental $2\nu\beta\beta$ NME, the consequent $0\nu\beta\beta$ NME with the tensor interaction is close to that without the tensor interaction within a 10% difference.
The effects of the tensor force on the
2025, 49(7): 074109. doi: 10.1088/1674-1137/adc65b
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The ground state properties of finite, bulk matter, and neutron stars are investigated using a proposed effective interaction (HPU4) of the relativistic mean field model (RMF) that incorporates self and cross-couplings of σ, ω, and ρ mesons with nucleons. This interaction has been constructed by fitting data on binding energies and charge radii of finite nuclei, neutron skin ($\Delta r_{{np}}$ ) of $ ^{48} {\rm{Ca}}$ nucleus, and astrophysical observations of the maximum masses of neutron stars. $\Delta r_{np}$ ($ ^{48} {\rm{Ca}}$ ) = 0.146±0.019 fm is achieved with soft symmetry energy ($ J_{0} $ = 27.91±1.31 MeV) and its corresponding slope ($ L_{0} $ = 42.85±14.26 MeV) at saturation density. An equation of state (EoS) with a composition of β-equilibrated nucleonic and leptonic matter is computed. The nuclear matter and neutron star properties are also analyzed for this interaction and agree well with the astrophysical observations, such as the NICER and GW170817 events. We also perform a statistical analysis to estimate the theoretical errors in coupling parameters and neutron star observables and to determine the correlation coefficients. We observe that the neutron skins of $ ^{208} {\rm{Pb}}$ and $ ^{48} {\rm{Ca}}$ are strongly correlated and exhibit a strong dependence on $ J_{0} $ , $ L_{0} $ and the curvature of symmetry energy ($ K_{\text{sym}} $ ) as suggested from their correlations. A strong correlation of $ R_{1.4} $ with ρ-meson-nucleon coupling quantified by the term $ g_{\rho N} $ and mixed interaction terms $ \sigma\rho_{\mu}\rho^{\mu} $ and $ \sigma^{2}\rho_{\mu}\rho^{\mu} $ is also observed.
The ground state properties of finite, bulk matter, and neutron stars are investigated using a proposed effective interaction (HPU4) of the relativistic mean field model (RMF) that incorporates self and cross-couplings of σ, ω, and ρ mesons with nucleons. This interaction has been constructed by fitting data on binding energies and charge radii of finite nuclei, neutron skin (
2025, 49(7): 074103. doi: 10.1088/1674-1137/adc7e4
Abstract:
This paper presents a comprehensive investigation of the true ternary fission of the$ ^{248}\text{Cf} $ isotope. Using the Three-Cluster Model ($ \text{TCM} $ ) based on the $ \text{WKB} $ approximation, detailed calculations were performed for all possible fragment configurations, considering the equatorial and collinear geometries. The fragment charge numbers (Z) were systematically filtered within the range of $ Z = 20 $ to $ Z = 52 $ , and all combinations were examined for three positional arrangements: fragments $ A_{1} $ , $ A_{2} $ , and $ A_{3} $ occupying the middle position in collinear geometry. For each combination, key quantities were calculated, including driving potential (${V {\text{-}} Q}$ ), penetration probability (P), relative yield (Y), decay constant (λ), and half-life ($ T_{\frac{1}{2}} $ ). The selection of optimal fragment combinations was based on higher penetration probability or minimum driving potential, ensuring a systematic approach to identifying the most favorable fission configurations. Redundancy from permutations of $ Z_{1} $ , $ Z_{2} $ , and $ Z_{3} $ was eliminated by treating them equivalently. The results highlight the significant influence of fragment geometry and nuclear structure, particularly shell effects, on the fission dynamics. This work provides new insights into the complex mechanisms of true ternary fission, contributing to the broader understanding of nuclear stability and fragment distributions in such processes. The novelty of this study relative to similar research is the investigation of the effects of fragments permutations, geometries, and neutron emission on the fission process.
This paper presents a comprehensive investigation of the true ternary fission of the
2025, 49(7): 074110. doi: 10.1088/1674-1137/add5d0
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Shape competition and coexistence between the pear- and the tetrahedral-shape octupole deformations in actinide nuclei is investigated by employing the realistic nuclear mean-field theory with the phenomenological, so-called 'universal' Woods-Saxon Hamiltonian with newly adjusted parameters containing no parametric correlations. Both types of octupole deformations exhibit significant effects in$ N=132 $ , $ N=134 $ , and $ N=136 $ isotones. Nuclear potential energy calculations within the multi-dimensional deformation spaces reveal that the tetrahedral deformation effects generally lead to deeper energy minima in most nuclei with $ N=134 $ and $ N=136 $ . Interestingly, in the nuclei $^{218}_{\;\;86}{\rm{Rn}}_{132} $ , $^{222}_{\;\;88}{\rm{Ra}}_{134} $ , and $^{222}_{\;\;86}{\rm{Rn}}_{136} $ , selected for the illustration of the studied effects, the influence of pear-shape octupole deformation is comparable to that of tetrahedral octupole deformation. Consequently, the coexistence of both kinds of octupole shapes is predicted by the potential energy calculations. In particular, we have reproduced the experimental results known for pear-shape rotational bands obtaining in this way an estimate of the quality of the modelling parametrisation. With the same Hamiltonian, we have predicted the properties of the tetrahedral symmetry rotational bands. To facilitate the possible experiment-theory cooperation we have derived the exact spin-parity tetrahedral-band structures by applying the standard methods of the group representation theory for the Td point-group.
Shape competition and coexistence between the pear- and the tetrahedral-shape octupole deformations in actinide nuclei is investigated by employing the realistic nuclear mean-field theory with the phenomenological, so-called 'universal' Woods-Saxon Hamiltonian with newly adjusted parameters containing no parametric correlations. Both types of octupole deformations exhibit significant effects in
Software defined radio for on-line interaction with beam processes in the heavy ion storage ring ESR
2025, 49(7): 074005. doi: 10.1088/1674-1137/adcc01
Abstract:
The application of software defined radio in on-line interactions with the beam processes of the heavy ion storage ring is presented. We discusse how this new technique can enhance the beam time efficiency and create new measurement possibilities. A specific example to halt the accelerator running if a rare stored particle is identified on-line is discussed.
The application of software defined radio in on-line interactions with the beam processes of the heavy ion storage ring is presented. We discusse how this new technique can enhance the beam time efficiency and create new measurement possibilities. A specific example to halt the accelerator running if a rare stored particle is identified on-line is discussed.
2025, 49(7): 074108. doi: 10.1088/1674-1137/add25a
Abstract:
For even Th and U nuclei, the description of the energies of yrast bands in the Harris variable moment of inertia model is studied in its phenomenological application. For some of these nuclei, the results obtained in the microscopic version of the interacting boson model (IBM) are presented, in which high-spin excitation modes are also considered. For other nuclei, in scenarios where high-spin orbits are not highly significant in describing the properties of yrast bands, in addition to the Harris model, the IBM with a full standard Hamiltonian constructed only from s and d bosons is utilized. Because the Harris model is considered with no more than four parameters, it can be used for both heavy and superheavy nuclei to approximate the energies of high-spin states. This study on the properties of nuclei using various models reveals the possibilities of describing different behaviors of the moments of inertia in the IBM and outlines additional criteria for the implementation of band crossing.
For even Th and U nuclei, the description of the energies of yrast bands in the Harris variable moment of inertia model is studied in its phenomenological application. For some of these nuclei, the results obtained in the microscopic version of the interacting boson model (IBM) are presented, in which high-spin excitation modes are also considered. For other nuclei, in scenarios where high-spin orbits are not highly significant in describing the properties of yrast bands, in addition to the Harris model, the IBM with a full standard Hamiltonian constructed only from s and d bosons is utilized. Because the Harris model is considered with no more than four parameters, it can be used for both heavy and superheavy nuclei to approximate the energies of high-spin states. This study on the properties of nuclei using various models reveals the possibilities of describing different behaviors of the moments of inertia in the IBM and outlines additional criteria for the implementation of band crossing.
2025, 49(7): 074006. doi: 10.1088/1674-1137/add099
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The opportunities and challenges of performing transfer reactions in inverse kinematics using the 16,18O beams at the experimental Cooler Storage Ring (CSRe) of the Heavy Ion Research Facility in Lanzhou (HIRFL) with the internal gas-jet target are discussed herein. The kinematics, differential cross sections for various transfer reactions using the 16,18O beam with incident energies of 30 and 100 MeV/nucleon, and the H2- or D2-gas-jet targets are compared. The 16O beam at 100 MeV/nucleon with an intensity of ≥106 pps interacting with the H2-gas-jet target is recommended as the first transfer reaction at HIRFL-CSRe.
The opportunities and challenges of performing transfer reactions in inverse kinematics using the 16,18O beams at the experimental Cooler Storage Ring (CSRe) of the Heavy Ion Research Facility in Lanzhou (HIRFL) with the internal gas-jet target are discussed herein. The kinematics, differential cross sections for various transfer reactions using the 16,18O beam with incident energies of 30 and 100 MeV/nucleon, and the H2- or D2-gas-jet targets are compared. The 16O beam at 100 MeV/nucleon with an intensity of ≥106 pps interacting with the H2-gas-jet target is recommended as the first transfer reaction at HIRFL-CSRe.
2025, 49(7): 074104. doi: 10.1088/1674-1137/adc2da
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In this study, the evolution of nuclear shape and rotational behavior along the yrast line in even-even$ ^{126-136} {\rm{Ba}}$ was systematically investigated using pairing self-consistent Woods-Saxon-Strutinsky calculations combined with the total Routhian surface (TRS) method in the ($ \beta_2, \gamma, \beta_4 $ ) deformation space. Empirical laws were applied to evaluate nuclear ground-state properties, revealing a shape evolution from axially deformed to non-axial vibrational configuration in even-even $ ^{126-136} {\rm{Ba}}$ isotopes. Particularly, an extreme γ-unstable shape was predicted in $ ^{130} {\rm{Ba}}$ . The shape transition of the ground state in these nuclei was confirmed by the TRS calculations. In addition, the evolution of the nuclear shape in high spin states with varying rotational axes associated with rotation around the medium, long, and short axes was elucidated from the TRS calculations. This variation was further characterized by the alignment of the $ \pi(h_{11/2})^2 $ and $ \nu(h_{11/2})^2 $ configurations, highlighting a preference for non-collective oblate/triaxial shapes with $ \gamma > 0^{\circ} $ and collective oblate/triaxial shapes with $ \gamma < 0^{\circ} $ , respectively.
In this study, the evolution of nuclear shape and rotational behavior along the yrast line in even-even
2025, 49(7): 074004. doi: 10.1088/1674-1137/adcb96
Abstract:
The distribution of nuclei produced in the 40Ar + 232Th reaction has been studied at the gas-filled recoil separator (SHANS2) at the China Accelerator Facility for Superheavy Elements (CAFE2). The bombardment was carried out at a beam energy of 205 MeV with the detection system installed at the focal plane. Forty-four isotopes heavier than 208Pb were observed. These isotopes were identified as the transfer reaction (or target-like) products, and their relative cross-sections were extracted. Based on the mass distribution of these products, we exclude the possibility that they were produced by fusion-fission reactions; thus, they may originate from quasi-fission of the 40Ar + 232Th reaction.
The distribution of nuclei produced in the 40Ar + 232Th reaction has been studied at the gas-filled recoil separator (SHANS2) at the China Accelerator Facility for Superheavy Elements (CAFE2). The bombardment was carried out at a beam energy of 205 MeV with the detection system installed at the focal plane. Forty-four isotopes heavier than 208Pb were observed. These isotopes were identified as the transfer reaction (or target-like) products, and their relative cross-sections were extracted. Based on the mass distribution of these products, we exclude the possibility that they were produced by fusion-fission reactions; thus, they may originate from quasi-fission of the 40Ar + 232Th reaction.
2025, 49(7): 074003. doi: 10.1088/1674-1137/adbad0
Abstract:
The Nuclotron-based Ion Collider fAcility (NICA), currently under construction at JINR, is expected to conduct its first beam tests in the second half of 2025. The NICA project is designed to provide colliding beams for investigating heavy stripped ion collisions at energies of 4.5 GeV/u. The NICA accelerator complex comprises several components: the operational heavy ion linac HILAC with an energy of 3.2 MeV/u, superconducting Booster synchrotron with a maximum energy of 600 MeV/u, superconducting Nuclotron synchrotron capable of accelerating gold ions to 3.9 GeV/u, and two storage rings with two interaction points currently under installation. The system includes two electron cooling units—one in the Booster synchrotron with a maximum electron energy of 60 keV, and another in the Collider with two electron beams, each with a maximum energy of 2.5 MeV. Additionally, two stochastic cooling systems are integrated into the setup. The status of the NICA accelerator complex, including its cooling systems, is presented. Experimental results from electron cooling studies conducted during the commissioning of the injection complex are reported. Plans for the further development and application of the electron and stochastic cooling systems are also described.
The Nuclotron-based Ion Collider fAcility (NICA), currently under construction at JINR, is expected to conduct its first beam tests in the second half of 2025. The NICA project is designed to provide colliding beams for investigating heavy stripped ion collisions at energies of 4.5 GeV/u. The NICA accelerator complex comprises several components: the operational heavy ion linac HILAC with an energy of 3.2 MeV/u, superconducting Booster synchrotron with a maximum energy of 600 MeV/u, superconducting Nuclotron synchrotron capable of accelerating gold ions to 3.9 GeV/u, and two storage rings with two interaction points currently under installation. The system includes two electron cooling units—one in the Booster synchrotron with a maximum electron energy of 60 keV, and another in the Collider with two electron beams, each with a maximum energy of 2.5 MeV. Additionally, two stochastic cooling systems are integrated into the setup. The status of the NICA accelerator complex, including its cooling systems, is presented. Experimental results from electron cooling studies conducted during the commissioning of the injection complex are reported. Plans for the further development and application of the electron and stochastic cooling systems are also described.
2025, 49(7): 074105. doi: 10.1088/1674-1137/adc097
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In the present work, based on a Gamow-like model, considering the deformation effect of Coulomb potential, where the effective nuclear radius constant is parameterized, we systematically investigate the cluster radioactivity half-lives of 25 trans-lead nuclei. For comparison, a universal decay law (UDL) proposed by Qi et al. [Phys. Rev. C 80, 044326 (2009)], a new semi-empirical formula for exotic cluster decay proposed by Balasubramaniam et al. [Phys. Rev. C 70, 017301 (2004)], and a scaling law proposed by Horoi [J. Phys. G: Nucl. Part. Phys. 30, 945 (2004)] are also used. The calculated results within the deformed Gamow-like model are in better agreement with the experimental half-lives. The deformation effect is also discussed within both the Gamow-like and deforemed Gamow-like models. Moreover, we extend this model to predict the cluster radioactivity half-lives of 49 nuclei whose decay energies are energetically allowed or observed but not yet quantified in NUBASE2020.
In the present work, based on a Gamow-like model, considering the deformation effect of Coulomb potential, where the effective nuclear radius constant is parameterized, we systematically investigate the cluster radioactivity half-lives of 25 trans-lead nuclei. For comparison, a universal decay law (UDL) proposed by Qi et al. [Phys. Rev. C 80, 044326 (2009)], a new semi-empirical formula for exotic cluster decay proposed by Balasubramaniam et al. [Phys. Rev. C 70, 017301 (2004)], and a scaling law proposed by Horoi [J. Phys. G: Nucl. Part. Phys. 30, 945 (2004)] are also used. The calculated results within the deformed Gamow-like model are in better agreement with the experimental half-lives. The deformation effect is also discussed within both the Gamow-like and deforemed Gamow-like models. Moreover, we extend this model to predict the cluster radioactivity half-lives of 49 nuclei whose decay energies are energetically allowed or observed but not yet quantified in NUBASE2020.
2025, 49(7): 074106. doi: 10.1088/1674-1137/adc121
Abstract:
In this study, we explore the possibilities of the formation of bound states of neutral pseudoscalar mesons$ \eta, \eta', D^{0} $ , $ \bar{D^{0}}, B^{0}, \bar{B^{0}} $ , and $ \bar{K^{0}} $ and the vector meson ϕ, with the nuclei $ ^{12} {\rm{C}}$ , $ ^{16} {\rm{O}}$ , $ ^{40} {\rm{C}}{\rm{a}}$ , and $ ^{208} {\rm{Pb}}$ , calculating their binding energy and absorption decay width. To calculate the optical potentials of these mesons in different nuclei under study, we use the chiral $S U $ (3) hadronic mean field model, in which the properties of nucleons in the medium are modified through the scalar isoscalar fields σ and ζ and scalar-isovector field δ. The scalar-isovector field δ accounts for the finite isospin asymmetry of different nuclei having asymmetry in the number of protons and neutrons. The binding energy and absorption decay width of mesons are calculated for the ground state and some possible excited states of the nuclei. In the chiral $S U$ (3) model, the mesons $\eta,\; D^{0}$ , $ \bar{D^{0}}, B^{0}, \bar{B^{0}} $ , and $ \bar{K^{0}} $ are observed to have a significant negative mass shift up to nuclear saturation density, which leads to the possibility of bound states at least for ground states and some excited states for heavy nuclei. For the pseudoscalar singlet $ \eta ' $ and vector meson ϕ, the mass shift obtained are found to be small, and bound states are not formed. The present calculations are compared with those of different studies conducted in the field and are useful in understanding the outcomes from different experimental facilities focusing on this area of research.
In this study, we explore the possibilities of the formation of bound states of neutral pseudoscalar mesons
2025, 49(7): 074002. doi: 10.1088/1674-1137/adc122
Abstract:
In-ring nuclear reactions induced by light-ions, which are characterized by low-momentum sensitivity and low background, play an important role in nuclear structure and astrophysics investigations. Recently, the in-ring proton-nucleus elastic scattering measurements at low momentum transfer based on the internal hydrogen-gas-jet target have been successfully performed at the Cooler Storage Ring of the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). In this proceeding, we present the progress of matter radius measurements using the small-angle differential cross sections of proton-nucleus elastic scattering at HIRFL-CSR.
In-ring nuclear reactions induced by light-ions, which are characterized by low-momentum sensitivity and low background, play an important role in nuclear structure and astrophysics investigations. Recently, the in-ring proton-nucleus elastic scattering measurements at low momentum transfer based on the internal hydrogen-gas-jet target have been successfully performed at the Cooler Storage Ring of the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR). In this proceeding, we present the progress of matter radius measurements using the small-angle differential cross sections of proton-nucleus elastic scattering at HIRFL-CSR.
2025, 49(7): 074107. doi: 10.1088/1674-1137/adc11e
Abstract:
An axially quadruple-octupole deformed relativistic Hartree-Fock (O-RHF) model with density-dependent meson-nucleon couplings is developed in this study. In this model, the reflection symmetry is not preserved, and the integro-differential Dirac equations are solved by expanding the Dirac spinor on the spherical Dirac Woods-Saxon basis. The reliability of the newly developed O-RHF model is demonstrated by taking the octupole nucleus$ ^{144} {\rm{Ba}}$ as an example, and the octupole deformation effects in $ ^{144} {\rm{Ba}}$ are analyzed using the RHF Lagrangians PKOi ($ i = 1,2,3 $ ) and RMF Lagrangian DD-ME2. We find that the O-RHF models reproduce the octupole deformation of $ ^{144} {\rm{Ba}}$ within the uncertainty of experimental results. Moreover, the presence of the Fock terms can enhance the intrusion of the neutron $ 1i_{13/2} $ and proton $ 1h_{11/2} $ waves, which leads to enhanced effects of octupole deformation for $ ^{144} {\rm{Ba}}$ . In particular, owing to the repulsive tensor coupling between the intruding waves and the core of $ ^{144} {\rm{Ba}}$ , the tensor force component carried by the π-PV coupling, which contributes only via the Fock terms, likely plays an unfavorable role in the occurrence of the octupole deformation of $ ^{144} {\rm{Ba}}$ .
An axially quadruple-octupole deformed relativistic Hartree-Fock (O-RHF) model with density-dependent meson-nucleon couplings is developed in this study. In this model, the reflection symmetry is not preserved, and the integro-differential Dirac equations are solved by expanding the Dirac spinor on the spherical Dirac Woods-Saxon basis. The reliability of the newly developed O-RHF model is demonstrated by taking the octupole nucleus
2025, 49(7): 074001. doi: 10.1088/1674-1137/adc7e5
Abstract:
Bremsstrahlung fluxes for irradiating tantalum samples were formed by irradiating a tungsten converter with an electron beam having energy up to 130 MeV. The relative yields and flux-averaged cross-sections of multinucleon photonuclear reactions that emit up to nine neutrons in 181Ta nuclei were determined. Monte Carlo simulations for studying the yields of photonuclear reactions were performed using Geant4 and TALYS-2.0 codes. The obtained experimental results were compared with available literature data and calculated results. The comparison showed that the values of the relative reaction yield and flux-averaged cross-section coincide with the literature data, considering the different geometries of the experiments. The calculated results coincide with the experimental ones only for reactions that emit up to five neutrons from the nucleus.
Bremsstrahlung fluxes for irradiating tantalum samples were formed by irradiating a tungsten converter with an electron beam having energy up to 130 MeV. The relative yields and flux-averaged cross-sections of multinucleon photonuclear reactions that emit up to nine neutrons in 181Ta nuclei were determined. Monte Carlo simulations for studying the yields of photonuclear reactions were performed using Geant4 and TALYS-2.0 codes. The obtained experimental results were compared with available literature data and calculated results. The comparison showed that the values of the relative reaction yield and flux-averaged cross-section coincide with the literature data, considering the different geometries of the experiments. The calculated results coincide with the experimental ones only for reactions that emit up to five neutrons from the nucleus.
2025, 49(7): 074102. doi: 10.1088/1674-1137/adc4ca
Abstract:
This article describes a series of studies on the effect of the rotation of the fissile 236U nucleus in the 235U(n,f) process induced by monochromatic polarized neutrons with energies of 62 meV and 270 meV. The studied effect is expressed as a shift in the anisotropic angular distribution of γ-rays emitted by excited fission fragments by a small angle relative to the deformation axis of the fissile nucleus when the neutron beam polarization direction is reversed. All measurements were performed at the Heinz Mayer-Leibniz research neutron source (FRM II reactor) of the Munich Technical University in Garching on the polarized neutron beam of the POLI instrument. To generalize all results obtained on ROT effects for fission γ-rays, the results of earlier studies by the ITEP group for cold neutrons are re-processed, and the result obtained by the PNPI group for thermal neutrons is also presented.
This article describes a series of studies on the effect of the rotation of the fissile 236U nucleus in the 235U(n,f) process induced by monochromatic polarized neutrons with energies of 62 meV and 270 meV. The studied effect is expressed as a shift in the anisotropic angular distribution of γ-rays emitted by excited fission fragments by a small angle relative to the deformation axis of the fissile nucleus when the neutron beam polarization direction is reversed. All measurements were performed at the Heinz Mayer-Leibniz research neutron source (FRM II reactor) of the Munich Technical University in Garching on the polarized neutron beam of the POLI instrument. To generalize all results obtained on ROT effects for fission γ-rays, the results of earlier studies by the ITEP group for cold neutrons are re-processed, and the result obtained by the PNPI group for thermal neutrons is also presented.
2025, 49(7): 074101. doi: 10.1088/1674-1137/adc3fd
Abstract:
To explore the possible existence of nuclear chirality in the$ A\approx 60 $ mass region, we study the doublet bands built on the configuration $ \pi f_{7/2}^{-1} \otimes \nu g_{9/2}^{1} $ using the particle rotor model (PRM) with residual proton-neutron interactions $ V_{pn} $ for cobalt isotopes. The energy spectra $ E(I) $ , energy difference between the doublet bands $ \Delta E(I) $ , electromagnetic transition probabilities $ B(M1) $ and $ B(E2) $ , and the energy staggering $ S(I) $ of the doublet bands are calculated by varying the deformation parameters β and γ and moment of inertia $ \mathscr{J} $ . The PRM calculations show that the parameters for the ideal chirality of the configuration $ \pi f_{7/2}^{-1} \otimes \nu g_{9/2}^{1} $ are $ \beta=0.25 $ , $ \gamma=34^{\circ} $ , and $\mathscr{J}= $ $ 10\; \hbar^2/\rm MeV$ . Subsequently, PRM calculations adopting these parameters show that $ \Delta E(I) $ and $ S(I) $ are sensitive to the residual proton-neutron interactions $ V_{pn} $ . A weaker $ V_{pn} $ is more conducive to the existence of nuclear chirality. Finally, the evolution of the chirality with spin I is illustrated using the probability of the total angular momentum along the principal axes (K distribution) and the orientation with respect to the intrinsic frame $ \mathscr{P}(\theta,\varphi) $ .
To explore the possible existence of nuclear chirality in the
2025, 49(7): 073104. doi: 10.1088/1674-1137/add5c5
Abstract:
We explore the properties of vector dark matter (DM) particles that predominantly interact with Standard Model (SM) electroweak gauge bosons using an effective field theory approach. The study emphasizes effective contact interactions, invariant under the SM gauge group, between vector DM and SM-neutral electroweak gauge bosons. Focusing on interaction terms up to dimension-eight, we establish constraints on the model parameters based on the observed DM relic density and indirect detection signals. We also examine the prospects for dark matter-nucleon scattering in direct detection experiments. In addition, we analyze the sensitivity of low-energy LEP data to the pair production of light DM particles (with masses up to 80 GeV). Finally, we assess the potential of the proposed International Linear Collider to probe these effective operators through the detection of DM particles produced in association with mono-photons.
We explore the properties of vector dark matter (DM) particles that predominantly interact with Standard Model (SM) electroweak gauge bosons using an effective field theory approach. The study emphasizes effective contact interactions, invariant under the SM gauge group, between vector DM and SM-neutral electroweak gauge bosons. Focusing on interaction terms up to dimension-eight, we establish constraints on the model parameters based on the observed DM relic density and indirect detection signals. We also examine the prospects for dark matter-nucleon scattering in direct detection experiments. In addition, we analyze the sensitivity of low-energy LEP data to the pair production of light DM particles (with masses up to 80 GeV). Finally, we assess the potential of the proposed International Linear Collider to probe these effective operators through the detection of DM particles produced in association with mono-photons.
2025, 49(7): 073102. doi: 10.1088/1674-1137/adc084
Abstract:
This work conducts a comprehensive analysis of the mass spectra and decay properties of bottomonium states using a relativistic screened potential model. The mass spectrum, decay constants,$ E1 $ transitions, $ M1 $ transitions, and annihilation decay widths are evaluated. The interpretation of $ \Upsilon(10355) $ , $ \Upsilon(10580) $ ,$ \Upsilon(10860) $ , and $ \Upsilon(11020) $ as $ S-D $ mixed bottomonium states are analysed. The $ \Upsilon(10355) $ state is considered to be $ 3S-2D $ , $ \Upsilon(10580) $ and $ \Upsilon(10753) $ are considered to be $ 4S-3D $ mixed states, and the $ \Upsilon(10860) $ and $ \Upsilon(11020) $ are considered to be $ 5S-4D $ mixed states.
This work conducts a comprehensive analysis of the mass spectra and decay properties of bottomonium states using a relativistic screened potential model. The mass spectrum, decay constants,
2025, 49(7): 073101. doi: 10.1088/1674-1137/adcc8a
Abstract:
We study the new$Z'$ boson as a portal for the production of Higgs bosons $h_0$ and $H_0$ predicted by the Bestest Little Higgs Model through Higgs-strahlung processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$ . We focus on the resonant and nonresonant effects of the $Zh_0, ZH_0$ signals. In our analysis, we consider the center-of-mass energies of $\sqrt{s}=3, 4, 6, 10, 30$ TeV and integrated luminosities of ${\cal{L}}=2, 4, 6, 10, 30$ ${ {\rm{ab}}^{-1}}$ projected for a future muon collider. The possibility of performing precision measurements for Higgs bosons $h_0$ and $H_0$ is very promising for the future muon collider. Furthermore, our results may be useful to the High Energy Physics community. Complementarily, we generate and provide the Feynman rules necessary for studying processes $\mu^+\mu^- \to (Z, Z') \to Zh_0, ZH_0$ .
We study the new
2025, 49(7): 075105. doi: 10.1088/1674-1137/adc188
Abstract:
This study explores black holes in general relativity (GR) coupled with nonlinear electrodynamics (NED) in the presence of perfect fluid dark matter (PFDM). We derive a singular black hole solution and investigate its thermodynamic properties, including the black hole temperature, entropy, and specific heat capacity of the black hole spacetime. The analysis of energy conditions reveals deviations from standard GR, with PFDM affecting the weak and strong energy conditions. The study further examines the impact of NED and PFDM on the innermost stable circular orbit (ISCO), demonstrating that PFDM shifts the ISCO radius and that the combined effects of NED and PFDM field parameters sufficiently influence orbital stability. Our analysis of the black hole shadow reveals that PFDM increases the shadow radius, while a higher charge reduces it, leading to modifications in potential astrophysical observables. The thermodynamic behavior of the black hole exhibits phase transitions marked by changes in heat capacity, indicating possible stability regimes. Moreover, we derive equations for black hole shadow size and study the spacetime effects on the shadow. These results provide a framework for testing alternative gravity theories and understanding the role of exotic matter in strong gravitational fields. Finally, we compare the constraints on NED and PFDM field parameters derived from our black hole model with the Event Horizon Telescope (EHT) observations of M87* and Sgr A*, providing observational limits on deviations from GR.
This study explores black holes in general relativity (GR) coupled with nonlinear electrodynamics (NED) in the presence of perfect fluid dark matter (PFDM). We derive a singular black hole solution and investigate its thermodynamic properties, including the black hole temperature, entropy, and specific heat capacity of the black hole spacetime. The analysis of energy conditions reveals deviations from standard GR, with PFDM affecting the weak and strong energy conditions. The study further examines the impact of NED and PFDM on the innermost stable circular orbit (ISCO), demonstrating that PFDM shifts the ISCO radius and that the combined effects of NED and PFDM field parameters sufficiently influence orbital stability. Our analysis of the black hole shadow reveals that PFDM increases the shadow radius, while a higher charge reduces it, leading to modifications in potential astrophysical observables. The thermodynamic behavior of the black hole exhibits phase transitions marked by changes in heat capacity, indicating possible stability regimes. Moreover, we derive equations for black hole shadow size and study the spacetime effects on the shadow. These results provide a framework for testing alternative gravity theories and understanding the role of exotic matter in strong gravitational fields. Finally, we compare the constraints on NED and PFDM field parameters derived from our black hole model with the Event Horizon Telescope (EHT) observations of M87* and Sgr A*, providing observational limits on deviations from GR.
2025, 49(7): 075103. doi: 10.1088/1674-1137/adc2db
Abstract:
Compact binary systems lose orbital energy and momentum because of gravitational radiation. Based on the mass and mass-current multipole moments of the binary system with the spin vector defined by Bohé et al. [Class. Quantum Grav. 30, 075017 (2013)], we calculate the loss rates of energy, angular momentum and linear momentum induced by the next-to-leading spin-orbit effects. For the case of circular orbit, the formulations the these losses are formulated in terms of orbital frequency.
Compact binary systems lose orbital energy and momentum because of gravitational radiation. Based on the mass and mass-current multipole moments of the binary system with the spin vector defined by Bohé et al. [Class. Quantum Grav. 30, 075017 (2013)], we calculate the loss rates of energy, angular momentum and linear momentum induced by the next-to-leading spin-orbit effects. For the case of circular orbit, the formulations the these losses are formulated in terms of orbital frequency.
2025, 49(7): 075101. doi: 10.1088/1674-1137/adcc8d
Abstract:
Quasars serve as important cosmological probes; constructing accurate luminosity relations for them is essential for their use in cosmology. If the coefficients of such luminosity relations vary with redshift, they could introduce biases into cosmological constraints derived from quasars. In this paper, we conduct a detailed analysis of the redshift variation in the X-ray and ultraviolet (UV) luminosity ($ L_\mathrm{X} $ -$ L_\mathrm{UV} $ ) relations of quasars. For the standard $ L_\mathrm{X} $ -$ L_\mathrm{UV} $ relation, we show that the relation coefficients exhibit a strong and linear correlation with redshift that is not attributable to the selection effect. Additionally, we examine two three-dimensional, redshift-evolving $ L_\mathrm{X} $ -$ L_\mathrm{UV} $ relations and show that the inclusion of a redshift-dependent term does not eliminate the impact of redshift evolution, given that the relation coefficients continue to evolve with redshift. Finally, we construct a new $ L_\mathrm{X} $ -$ L_\mathrm{UV} $ relation in which the redshift evolution of the relation coefficients is nearly eliminated. By calibrating the luminosity relations using Hubble parameter measurements, we demonstrate that quasars based on the proposed relation yield effective constraints on cosmological parameters that are consistent with results from Planck CMB data, unlike constraints derived from the standard relation.
Quasars serve as important cosmological probes; constructing accurate luminosity relations for them is essential for their use in cosmology. If the coefficients of such luminosity relations vary with redshift, they could introduce biases into cosmological constraints derived from quasars. In this paper, we conduct a detailed analysis of the redshift variation in the X-ray and ultraviolet (UV) luminosity (
2025, 49(7): 075104. doi: 10.1088/1674-1137/adc3fc
Abstract:
In this study, we investigate the optical appearance of a charged black hole in the Kalb-Ramond background, incorporating a Lorentz-violating parameter$ l=0.01 $ . By analyzing the null geodesics, we derive the photon sphere, event horizon, effective potential, and critical impact parameters. We then employ a ray-tracing technique to study the trajectories of photons surrounding a thin accretion disk. Three different emission models are considered to explore the observed intensity profiles of direct rings, lensing rings, and photon sphere. By comparing these results with those of the standard Reissner-Nordström black hole ($ l=0 $ ) and the Kalb-Ramond black hole with different values of the Lorentz-violating parameter (specifically, $ l=0.05 $ and $ l=0.1 $ ), we find that Lorentz symmetry breaking leads to a decrease in the radii of the photon sphere, event horizon, and innermost stable circular orbit. Consequently, the detection of these black holes is more challenging.
In this study, we investigate the optical appearance of a charged black hole in the Kalb-Ramond background, incorporating a Lorentz-violating parameter
2025, 49(7): 075102. doi: 10.1088/1674-1137/adc7e1
Abstract:
Due to quantum gravitational effects, Barrow proposed that the black hole horizon is "fractalized" into a sphereflake. Based on this idea, in this work we investigate the phase structure and stability of Einstein-Power-Yang-Mills (EPYM) AdS black holes in the restricted phase space, assuming the black hole event horizon has a fractal structure. From the first law of thermodynamics for EPYM AdS black holes in the restricted phase space, we find that the mass parameter should be interpreted as the internal energy. Moreover, the Smarr relation for this system in the restricted phase space is not a homogeneous function due to the fractal structure, which differs significantly from the corresponding relation in the extended phase space. The presence of a fractal structure can be regarded as a probe for phase transitions. Interestingly, for a fixed central charge in the EPYM AdS black hole system with a fractal structure, a supercritical phase transition also exists, similar to the case in the standard EPYM AdS black hole system. Furthermore, we investigate the effects of the fractal parameter ∆ and non-linear Yang-Mills parameter γ on the thermodynamical stability of this system are also investigated.
Due to quantum gravitational effects, Barrow proposed that the black hole horizon is "fractalized" into a sphereflake. Based on this idea, in this work we investigate the phase structure and stability of Einstein-Power-Yang-Mills (EPYM) AdS black holes in the restricted phase space, assuming the black hole event horizon has a fractal structure. From the first law of thermodynamics for EPYM AdS black holes in the restricted phase space, we find that the mass parameter should be interpreted as the internal energy. Moreover, the Smarr relation for this system in the restricted phase space is not a homogeneous function due to the fractal structure, which differs significantly from the corresponding relation in the extended phase space. The presence of a fractal structure can be regarded as a probe for phase transitions. Interestingly, for a fixed central charge in the EPYM AdS black hole system with a fractal structure, a supercritical phase transition also exists, similar to the case in the standard EPYM AdS black hole system. Furthermore, we investigate the effects of the fractal parameter ∆ and non-linear Yang-Mills parameter γ on the thermodynamical stability of this system are also investigated.
2025, 49(7): 073001. doi: 10.1088/1674-1137/adc88d
Abstract:
Utilizing 4.5$ \text{fb}^{-1} $ of $ e^+e^- $ annihilation data collected at center-of-mass energies ranging from 4599.53 MeV to 4698.82 MeV by the BESIII detector at the BEPCII collider, we searched for singly Cabibbo-suppressed hadronic decays $ \Lambda_{c}^{+}\to\Sigma^{0} K^{+}\pi^{0} $ and $ \Lambda_{c}^{+}\to\Sigma^{0}K^{+} \pi^+ \pi^- $ with a single-tag method. No significant signals were observed for both decays. The upper limits on the branching fractions at the 90% confidence level were determined to be $ 5.0\times 10^{-4} $ for $ \Lambda_{c}^{+}\to\Sigma^{0} K^{+}\pi^{0} $ and $ 6.5\times 10^{-4} $ for $ \Lambda_c^{+}\to\Sigma^0K^{+}\pi^{+}\pi^{-} $ .
Utilizing 4.5
2025, 49(7): 071001. doi: 10.1088/1674-1137/adc120
Abstract:
We propose the weak magnetic effect, which emerges as the dissipative correction to the quark phase space distribution function in quark-gluon plasma close to local thermal equilibrium, as a novel contribution to the observed Lambda hyperon local spin polarization. A finite field strength that is consistent with previous estimates of the magnetic field in heavy-ion collisions can be used to xplain the experimentally observed Lambda local spin polarization through all centrality classes. Moreover, the weak magnetic effect plays an unambiguous role in the ordering between the second-order and third-order modulations of experimental Lambda local spin polarization.
We propose the weak magnetic effect, which emerges as the dissipative correction to the quark phase space distribution function in quark-gluon plasma close to local thermal equilibrium, as a novel contribution to the observed Lambda hyperon local spin polarization. A finite field strength that is consistent with previous estimates of the magnetic field in heavy-ion collisions can be used to xplain the experimentally observed Lambda local spin polarization through all centrality classes. Moreover, the weak magnetic effect plays an unambiguous role in the ordering between the second-order and third-order modulations of experimental Lambda local spin polarization.
2025, 49(7): 071002. doi: 10.1088/1674-1137/adcc8f
Abstract:
The angular distribution of elastic scattering is highly sensitive to the surface region of the nucleus, making it a powerful tool for measuring the neutron skin thickness. Utilizing the CDM3Y6 double-folding potential, we extracted the neutron skin thickness of$ ^{124} $ Sn from the $ ^{12} $ C + $ ^{124} $ Sn elastic scattering angular distribution, obtaining values of $ 0.168_{\text{−}0.019}^{+0.025} $ fm (SLy4) and $ 0.177 \pm 0.022 $ fm (SLy7). These results are consistent with measurements from various other methods. Furthermore, through correlation analysis between the neutron skin thickness and nuclear symmetry energy slope parameter L, we determined the symmetry energy slope coefficients to be $ L = 39.0_{\text{−}16.5}^{+20.8} $ MeV (SLy4) and $L = 46.1 \pm 18.7$ MeV (SLy7) based on the scattering data. These findings validate existing theoretical models and provide valuable insights for further studies on neutron stars and nuclear matter properties.
The angular distribution of elastic scattering is highly sensitive to the surface region of the nucleus, making it a powerful tool for measuring the neutron skin thickness. Utilizing the CDM3Y6 double-folding potential, we extracted the neutron skin thickness of
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