The nucleon spin-orbit interaction is a cornerstone of modern nuclear theory, yet its isospin dependence remains elusive due to the lack of clean experimental probes. It has been recently demonstrated that within Skyrme-like energy density functionals, the charge-weak form factor difference ΔF_ CW in ^48Ca exhibits remarkable sensitivity to the isovector spin-orbit (IVSO) interaction, and that a significantly enhanced IVSO strength can resolve the PREX-CREX puzzle. Extending this analysis to other nuclei, we identify that ^90Zr, with its ten spin-orbit unpaired 1g_9/2 neutrons, displays a ΔF_CW sensitivity to the IVSO strength similar to that of ^48Ca, arising from modifications to the central mean-field potential rather than the one-body spin-orbit potential. In contrast, ^208Pb and ^62Ni remain largely insensitive to the IVSO interaction. Furthermore, this structure-driven distinction suggests a distinct experimental strategy: future parity-violating electron scattering measurements on ^48Ca and ^90Zr would enable a more precise determination of the IVSO strength, while measurements on ^208Pb and ^62Ni can serve as purer constraints on the symmetry energy slope.

In theory, burst activity of the magnetar can lead to the formation of fireballs trapped by the magnetic field and corotating with the star. However, smoking-gun observational evidence of the fireball is elusive. We envisage that the fireball emission should occasionally be eclipsed by the magnetar, especially when the burst duration is comparable to the magnetar's spin period. In this work, we first discover a peculiar type of burst whose light curve has a plateau-like feature among the long bursts of the magnetar SGR J1935+2154 detected by GECAM and Fermi/Gamma-ray Burst Monitor. Then, based on these bursts, we identified four burst candidates with eclipse-like characteristics. By fitting their light curves with the eclipse fireball model, the viewing angle of the magnetar relative to its spin axis is estimated to be 17 degrees +/- 10 degrees, and the distances from the fireballs to the magnetar are found to be more than 5 times the magnetar's radius, indicating that the fireballs are suspended in the magnetosphere rather than adhering to the magnetar surface. Furthermore, we find that this configuration is well consistent with the implication of the cyclotron resonance scattering feature we found in their spectra. Our results suggest that some intermediate X-ray bursts may originate from magnetic reconnection within the magnetosphere rather than the starquake.

Abstract High-energy cosmic-ray monitoring in low Earth orbit (LEO) is important for space science and exploration, yet it is usually limited to the dedicated cosmic-ray detectors. Here we show that GECAM, although designed as a gamma-ray all-sky monitor, can monitor high-energy cosmic rays through its novel design of simultaneous-event (STE). We first combine multi-component incident-particle models with \textsc{Geant4} simulations to calibrate the particle component--energy--multiplicity response of STE, and then apply to the GECAM observation data during geomagnetic storms. The simulations show that STE signals are dominated by GeV--TeV protons, whereas the highest-fold channels, especially STE(21--25), contain a significant contribution from $\sim 10$--$20$ GeV electrons. Thus, STE(5--20) mainly trace rigidity-dependent variations of primary protons, while STE(21--25) provides an electron-sensitive diagnostic. By analyzing the GECAM observation data during geomagnetic storms, we find a STE multiplicity-dependent response which is consistent with rigidity-dependent Forbush modulation and time-dependent geomagnetic transmissivity near cutoff and penumbral regions. These results demonstrate that GECAM can monitor high-energy cosmic-ray variations in LEO as a Micro Cosmic-Ray Observatory (MICRO), complementing those dedicated cosmic-ray instruments.

Although light nuclear clusters are known to form abundantly in warm and dilute nuclear matter, their role in hot and dense nuclear matter remains unclear due to the lack of experimental indication for their modifications by the Mott effect under such conditions. To address this issue, we resort to intermediate-energy heavy-ion collisions, where light clusters are mainly produced in the transiently formed hot and dense matter. A kinetic approach, which includes dynamically the formation and dissociation of light clusters, is employed to deduce the strength of the Mott effect and the α -particle fraction in hot and dense nuclear matter from the light-nuclei yields measured by the FOPI Collaboration in central Au + Au collisions at energies of 0.25 A to 0.6 A GeV . We find an unexpectedly abundant α clustering in this environment, which will have profound implications for modeling the nuclear equation of state and describing supernovae and neutron star mergers.

Anisotropic flows in heavy-ion collisions provide a basic experimental observable to understand nuclear collision dynamics and to constrain the dense nuclear matter equation of state (EOS). Within the framework of the lattice Boltzmann-Uehling-Uhlenbeck transport model, we present a systematic study of proton anisotropic flow observables measured by the HADES Collaboration, by utilizing the recently developed nuclear effective interaction based on the density-, momentum-, and isospin-dependent N5LO Skyrme pseudopotential. In particular, we investigate the impacts of the momentum dependence of nucleon mean-field potentials, the stiffness of the symmetric nuclear matter (SNM) EOS, the high-density behaviors of the symmetry energy, and the in-medium modification of nucleon-nucleon elastic cross sections on proton directed (v1), elliptic (v2), triangular (v3), and quadrangular (v4) flows in Au+Au collisions at root sNN = 2.4 GeV. Our results show that the proton anisotropic flows are strongly sensitive to the momentum dependence of the nucleon mean-field potential as well as the incompressibility coefficient K0 of SNM. In addition, the transverse momentum dependence of the proton v2 exhibits a modest sensitivity to the higher-order skewness coefficient J0 and kurtosis coefficient I0 of SNM as well as the momentum dependence of the symmetry potential, while the transverse momentum dependence of the proton v1 is shown to modestly depend on the in-medium modification of nucleon-nucleon elastic cross sections. Moreover, the high-density symmetry energy seems to have limited effects on the proton anisotropic flows. These findings highlight the necessity of considering the momentum dependence of nucleon mean-field potentials including the symmetry potential, the higher-order characteristic parameters of the SNM EOS beyond K0, and the in-medium modification of nucleon-nucleon elastic cross sections, in future Bayesian transport model analyses on proton anisotropic flows in heavy-ion collisions at HADES energies, for the purpose of extracting information on the nuclear matter EOS as well as the associated underlying nuclear effective interactions.

The spectral evolution characteristics of the prompt emission in gamma-ray bursts (GRBs) have been extensively studied, but detailed investigations of the spectral evolution in a GRB flare remain lacking. In this work, we present the first analysis of spectral parameter evolution in a GRB flare through high-time-resolved spectral fitting of the brightest flare in GRB 221009A. We find that the alpha-flux, Ep-flux, and Ep-alpha relationships during both the overall phase and the rising phase of the flare can be well described by a simple power-law model, showing positive correlations. Therefore, we conclude that the brightest flare exhibits "double-tracking" behavior. Since values of alpha do not exceed the synchrotron "death line" (-2/3), we explain this phenomenon using the magnetic dissipation synchrotron radiation model. In the decay phase of the flare, the Ep-flux and Ep-alpha correlations become notably flatter, with their power-law indices decreasing significantly compared to those in the rising phase. This may be due to the fact that the next flare begins to erupt before the brightest flare has completely ended, resulting in the combined effects of both two flares. Our study of the spectral parameter relations of the brightest flare provides new insights into the radiation mechanisms of both the GRB prompt emission and flares.

Within the framework of SU(2) chiral perturbation theory, we derive the general solution of the QCD theta vacuum for an arbitrary vacuum phase, explicitly incorporating isospin-breaking effects from the light quark mass difference, and compute the temperature dependence of the topological susceptibility, higherorder cumulants, and the domain wall tension up to next-to-leading order. We find that the topological susceptibility agrees with lattice data at low temperatures but deviates at higher temperatures as expected from the breakdown of the chiral expansion; moreover, we demonstrate that the normalized fourth-order cumulant and the domain wall tension decrease monotonically with increasing temperature, while the normalized sixth-order cumulant exhibits the opposite behavior. These results extend earlier analyses by showing how isospin breaking reshapes the full hierarchy of topological charge cumulants and the dynamics of theta-vacuum domain walls, thereby offering new theoretical input on the theta-vacuum properties, which are relevant for axion-related effective theories in hot QCD matter.

The Wide-field X-ray Telescope (WXT) onboard the Einstein Probe (EP) produces a large post-detection candidate stream in which genuine astrophysical sources coexist with instrumental artifacts and Cosmic Ray events. We present M-EPDet, a three-step post-detection framework for real-time candidate vetting in EP-WXT lobster-eye Micro-pore Optics (MPO) data. The framework combines a ResNet-based Arm filter, a dual-branch temporal-spectral Cosmic Ray filter, and a background-aware Bayesian Blocks module for single-exposure variability screening. Using on-orbit EP-WXT observations, we report decoupled metrics for the cascading system. M-EPDet achieves a Real-Bogus Recall of 98.31% (98.53%× 99.78%) for genuine astrophysical sources, together with rejection rates of 92.99% for instrumental artifacts and 98.18% for Cosmic Ray events. In the final step, the Bayesian Blocks module flags 0.75% of the post-filtration observations, corresponding to a 99.25% reduction in candidate volume. The system is deployed in the EP-WXT pipeline as a lightweight real-time service, reducing the manual-inspection burden in candidate vetting.

Double parton scattering (DPS) corresponds to events where two parton-parton scatterings occur in a single hadron-hadron collision. The DPS effects may arise from the spectator scatterings that are somewhat related to semi-hard QCD activities. In this work, we investigate the DPS effects on the W -boson mass measurements. Especially, our analysis reveals that the DPS effects contribute additional missing transverse momenta from spectator scatterings as well as relevant inclusive cross sections, potentially altering the distribution of total missing transverse momenta. Consequently, the DPS effects have the potential to cause an increase in the measured W -boson mass by the CDF detector, which helps to understand the deviation of the CDF-II measurements from other measurements and the predicted value in the Standard Model. This could be further validated in upcoming studies, such as the W -like analyses of the Z boson production, which will potentially open new avenues for probing QCD dynamics in the semi-hard regime.

Flares are usually observed during the afterglow phases of Gamma-ray bursts (GRBs) in the soft-X-ray, optical, and radio bands—but rarely in the gamma-ray band. Despite its extraordinary brightness, GECAM-C has accurately measured both the bright prompt emission and flare emission of GRB 221009A without instrumental effects, offering a good opportunity to study the relation between them. In this work, we present a comprehensive analysis of the flare emission of GRB 221009A, which is composed of a series of flares. Among them, we identify an exceptionally bright flare with a record-breaking isotropic energy E _iso = 1.82 × 10 ^53 erg for GRB flares. It exhibits the highest peak energy ever detected in GRB flares, E _peak ∼ 300 keV, making it a genuine gamma-ray flare. It also shows rapid rise and decay timescales, significantly shorter than those of typical X-ray flares observed in the soft-X-ray or optical bands but comparable to those observed in prompt emissions. Despite these exceptional properties, the flare shares several common properties with typical GRB flares. We note that this is the first observation of a GRB flare in the keV–MeV band with sufficiently high temporal resolution and high statistics, bridging the last gap between the prompt emission and flare.

Flares are usually observed during the afterglow phase of Gamma-Ray Bursts (GRBs) in soft X-ray, optical and radio bands, but rarely in gamma-ray band. Despite the extraordinary brightness, GECAM-C has accurately measured both the bright prompt emission and flare emission of GRB 221009A without instrumental effects, offering a good opportunity to study the relation between them. In this work, we present a comprehensive analysis of flare emission of GRB 221009A, which is composed of a series of flares. Among them, we identify an exceptionally bright flare with a record-breaking isotropic energy E_ iso = 1.82 × 10^53 erg of GRB flares. It exhibits the highest peak energy ever detected in GRB flares, E_ peak∼ 300 keV, making it a genuine gamma-ray flare. It also shows rapid rise and decay timescales, significantly shorter than those of typical X-ray flares observed in soft X-ray or optical band, but comparable to those observed in prompt emissions. Despite these exceptional properties, the flare shares several common properties with typical GRB flares. We note that this is the first observation of a GRB flare in the keV-MeV band with sufficiently high temporal resolution and high statistics, which bridges the last gap between prompt emission and flare.

We present a phase-space excluded-volume approach applicable to both nuclear matter and nonequilibrium processes, such as heavy-ion collisions, to account for in-medium effects on light clusters. In this approach, light clusters can exist only if the nucleon one-body phase-space occupation of the surrounding nuclear medium-including explicit contributions from light clusters-is sufficiently low. The nucleon occupation is determined self-consistently by accounting for the interplay between in-medium effects and thermodynamic properties, thereby improving upon the conventional treatment based on an uncorrelated medium (i.e., an overall nucleonic Fermi-Dirac distribution) typically employed in studies of light clusters in nuclear matter. We apply the approach to evaluate the Mott momenta and the fractions of light clusters in nuclear matter. Their differences from results obtained under the uncorrelated-medium assumption are found to be moderate. The main advantage of the present approach lies in its ability to be integrated into dynamical models, enabling more accurate studies of in-medium effects on light clusters, based on their measured yields in heavy-ion collisions.

GECAM is a constellation of all-sky monitors in hard X-ray and gamma-ray band primarily aimed at high energy transients such as gamma-ray bursts, soft gamma-ray repeaters, solar flares and terrestrial gamma-ray flashes. As GECAM has the highest temporal resolution (0.1 μs) among instruments of its kind, it can identify the so-called simultaneous events (STE) that deposit signals in multiple detectors nearly at the same time (with a 0.3 μs window). However, the properties and origin of STE have not yet been explored. In this work, we implemented, for the first time, a comprehensive analysis of the STE detected by GECAM, including their morphology, energy deposition, and the dependence on the geomagnetic coordinates. We find that these STE probably result from direct interactions between high-energy charged cosmic rays and satellite. These results demonstrate that GECAM can detect, identify, and characterize high-energy cosmic rays, making it a Micro Cosmic-Ray Observatory (MICRO) in low Earth orbit.

Gravitational-wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) is a constellation of all-sky monitors in hard X-ray and gamma-ray bands, primarily observing high-energy transients such as gamma-ray bursts, soft gamma-ray repeaters, solar flares, and terrestrial gamma-ray flashes. As GECAM has the highest temporal resolution (0.1 μs) among instruments of its kind, it can identify the so-called simultaneous events (STEs) that deposit signals in multiple detectors nearly at the same time (with a time window of 0.3 μs). However, the properties and origin of STEs have not yet been explored. In particular, STEs may impact the observation of high-energy transients. In this work, we present the first systematic study of the properties of STEs detected by GECAM, including the morphology, energy deposition, and the dependence on the geomagnetic latitude. Based on their properties, we suggest that these STEs probably result from direct interactions between high-energy charged cosmic rays and the satellite. GEANT4 Monte Carlo simulations using the GECAM spacecraft mass model were carried out to provide additional support for this interpretation. Our result indicates that GECAM could potentially detect and characterize the high-energy cosmic rays through STEs, thereby extending its scientific capability.

Fast radio burst (FRB) is mysterious phenomenon with millisecond-duration radio pulses observed mostly from cosmological distance. The association between FRB 200428 and a magnetar X-ray burst (MXB) from SGR J1935 + 2154 has significantly advanced the understanding of FRB and magnetar bursts. However, it is uncertain whether this association between MXB and FRB (i.e. MXB/FRB 200428) is genuine or just coincidental only based on this single event. Here we report the discovery of a bright (similar to 7.6 x 10(-7) erg . cm(-2) in 1-250 keV) magnetar X-ray burst detected by Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) on 2022 October 14 (dubbed as MXB 221014) from SGR J1935 + 2154, which is associated with an FRB detected by Canadian Hydrogen Intensity Mapping Experiment and Green Bank Telescope. We conducted a detailed temporal and spectral analysis of MXB 221014 with GECAM data and find that it is a bright and typical (T-90 similar to 250 ms) X-ray burst from this magnetar. Interestingly, we find two narrow X-ray pulses in the MXB, one of which temporally aligns with the main pulse of the FRB 221014 similar to 5.70 ms latter than the peak time of FRB 221014), resembling the feature found in MXB/FRB 200428. Furthermore, we did comprehensive comparison between MXB/FRB 221014 and MXB/FRB 200428, and find that while the two events share several common features, they also exhibit distinct differences, highlighting the variety of the MXB-FRB association morphology. This finding not only confirms the association between MXB and FRB but also provides new insights into the mechanism of and the relationship between FRB and MXB.

High performance computing has attracted more attention in modern study of scientific computing. In this paper, we propose an unconditionally energy stable numerical scheme for the Allen-Cahn equation which is second-order accurate in both space and time. The scheme employs the alternating-direction implicit (ADI) splitting to decouple the computation of spatial derivatives and the Strang splitting to decouple the computation of the nonlinear term from the linear one. The decoupling in spatial dimensions and nonlinear terms allows easy implementations of high performance computing techniques. The resulting schemes, which we call the Strang directional splitting (SDS) schemes, are rigorously shown to enjoy the unconditional energy stability for a modified energy and the second-order accuracy in both space and time. The SDS method is further generalized to numerically solve variable-coefficient Allen-Cahn equations in arbitrarily high dimensions, where the unconditional energy stability is still ensured. Its numerical efficiency is demonstrated through extensive simulation results.

Within a lattice Boltzmann-Uehling-Uhlenbeck transport model coupled to a kinetic approach for light-cluster formation, we investigate the impact of explicit light-cluster degrees of freedom on collective flows in Au+Au collisions at FOPI energies with beam energies E_ beam= 120–1500 A MeV by using a density-, momentum-, and isospin-dependent N5LO Skyrme pseudopotential. We first benchmark the kinetic approach by comparing the calculated light-cluster yields with FOPI data in central Au+Au collisions. We then analyze the collective flows of protons and light nuclei (deuterons, tritons, ^3He, and ^4He) in mid-central collisions. For protons, calculations with and without dynamical light-cluster degrees of freedom are compared to quantify the influence of dynamical cluster formation on proton directed (v_1), elliptic (v_2), triangular (v_3), and quadrangular (v_4) flows. We find that the dynamical light-cluster effect appreciably modifies proton v_1–v_4 flows at E_ beam=120–150 A MeV, remains visible at E_ beam=250–400 A MeV, and gradually weakens at E_ beam≳ 600 A MeV. For light nuclei, the kinetic approach captures the overall beam-energy dependence of the FOPI flow data, with better agreement for E_ beam≥ 400 A MeV. We further examine the nucleon-number scaling of v_2/A in both model calculations and experimental data, finding that the kinetic light-cluster formation approach qualitatively reproduces the observed scaling behavior. These results highlight the importance of a dynamical treatment of light-cluster formation for interpreting collective flows in heavy-ion collisions below about 600 A MeV, although the clustering effects on proton flows are minor at higher collision energies.

The management of observing proposals is a critical operational component for modern astronomical facilities. As missions grow in complexity, the demand for efficient, fair, and adaptable proposal handling systems is increasingly pressing. Existing systems are often monolithic and tightly coupled to a specific observatory, lacking the flexibility to be easily adapted. This paper introduces AstroPropose, a novel, general-purpose framework for creating and managing astronomical observing proposal systems, derived from the architecture of the operational Einstein Probe Observing Proposal System (EOPS). AstroPropose is centered on a powerful visual workflow engine, enabling administrators to define and deploy entire proposal workflows through a graphical interface. Key features include a dynamic form builder, a configurable workflow engine, and a flexible role-based access control (RBAC) system. We present the complete architecture and data model. As validation, we detail how the framework’s design principles are embodied in EOPS, which has successfully managed two annual proposal cycles and handles daily time-critical Target of Opportunity (ToO) submissions for the Einstein Probe mission. To further demonstrate the framework’s generalizability, we present a second case study: its adaptation as the proposal management prototype for the Chinese Space Station Telescope (CSST), a multi-instrument survey mission with a dual-phase review process. AstroPropose, validated through the successful operation of EOPS and the rapid prototyping of the CSST system, is being prepared for an open-source release to the astronomical community.

The spectral evolution characteristics of the prompt emission in gamma-ray bursts (GRBs) have been extensively studied, but detailed investigations of spectral evolution in a GRB flare remain lacking. In this work, we present the first analysis of spectral parameter evolution in a GRB flare through high time-resolved spectral fitting of the Brightest Flare in GRB 221009A. We find that the α-Flux, E_p-Flux, and E_p-α relationships during both the overall phase and the rise phase of flare can be well described by simple power-law model, showing positive correlations. Therefore, we conclude that Brightest Flare exhibits "Double-tracking" behavior. Since values of α do not exceed the synchrotron "death line" (-2/3), we explain this phenomenon using a magnetic dissipation synchrotron radiation model. In the decay phase of flare, the E_p-Flux and E_p-α correlations become notably flatter, with their power-law indices decreasing significantly compared to those in the rise phase. This may be due to the fact that the next flare begins to erupt before the Brightest Flare has completely ended, resulting in the combined effects of both two flares. Our study of spectral parameter relations of the Brightest Flare provides new insights into the radiation mechanisms of both GRB prompt emission and flares.